Publications

Hennige, SJ, Suggett, DJ, Hepburn, LJ, Pugsley, A, Crabbe, J & Smith, DJ 2013, 'Coral reefs of the Wakatobi: Processes of reef growth and loss' in Marine Research and Conservation in the Coral Triangle, Nova, USA, pp. 27-44.
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Coral reef accretion (net reef growth) is the result of complex and dynamic interactions between reef building organisms, bioeroders and the environment. Coral calcification often forms the 'measureable' portion of net reef growth, and is dependent upon the successful symbiotic relationship between cnidaria and photosynthetic dinoflagellate microalgae (Symbiodinium spp.). Light is thus a crucial resource for coral growth. Processes of reef loss include abiotic (storms, disturbance events and climate change) and biotic (bioeroders and corralivores) factors. To assess reef accretion, an understanding of the relationship between coral growth and loss, environmental variables and biotic eroders is vital. Reef systems that have both high biodiversity and varied environmental conditions are prime 'study grounds' to assess these complex interactions. An important example is the Wakatobi National Park (WNP), which is a centre for biodiversity but also has active long-term projects across a range of environments. This chapter examines the underlying physiology of the coral symbiotic relationship, and how this relates to reef growth by using studies from both the WNP and other systems. Understanding these processes remains a critical first step in any reef management strategy plan, but current methods by which reef growth can be assessed often lack the resolution and accuracy needed to relate to changes of environment. Consequently, this chapter discusses benefits and limitations of certain techniques used to assess reef growth. Ultimately, accurate coral growth measurements will improve our ability to model future ecosystem change, and should therefore be a priority research area to support future reef management and conservation strategies. Processes of reef loss are then discussed with regard to the impact of bioeroders, environmental perturbations and anthropogenic stressors upon primary and secondary reef framework. © 2010 by Nova Science Publishers, Inc. Al...

Larkum, AWD 2013, 'The Golden Apples of the Sun: the History of Photosynthesis—so Far' in Advanced Topics in Science and Technology in China, Springer Berlin Heidelberg, pp. 834-839.
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© Zhejiang University Press, Hangzhou and Springer-Verlag Berlin Heidelberg 2013. This article reviews the start of life and of photosynthesis on the Earth. A pivotal evolutionary event in photosynthesis was the ability to use water as the source of hydrogen in the photosynthetic reaction, which occurred about 2.35 billion years ago. This opened up the possibility for photosynthetic organisms to live anywhere on the surface of the Earth where light and water occurred—and secondarily allowed the build-up of oxygen in the biosphere and atmosphere. The accumulation of molecular oxygen allowed the evolution of aerobic respiratory systems with much greater efficiency in output of organically-derived energy. In turn this allowed the evolution of large complex eukaryotic cells by endosymbiosis. The chloroplast was the result of one endosymbiotic development, now found in many phyla of photosynthetic protists (algae) and in land plants. The multicellular land plants, which evolved from streptophyte green algae, now account for a major part of the total bioenergy production from photosynthesis on the Earth. However, the basic mechanism of photosynthesis has changed very little in the last 2 billion years. In the future, radical changes will be necessary to make bioenergy production from algae and plants more efficient and more competitive with other methods of solar energy conversion.

Li, Y, Larkum, A, Schliep, M, Kühl, M, Neilan, B & Chen, M 2013, 'Newly Isolated Chl d-Containing Cyanobacteria' in Kuang, T, Lu, C & Zhang, L (eds), Advanced Topics in Science and Technology in China, Springer Berlin Heidelberg, Beijing, pp. 686-690.
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Stromatolites are sedimentary structures formed by microbial mats that are typically found in limestone-or dolostone-rich environments. Shark Bay, Australia, has abundant examples of living marine stromatolites. Although the stromatolites from Shark Bay are only about 20003000 years old, they are similar to fossilized evidence of life found on Earth up to 3.5 billion years ago. Using infra-red light centred at 720 nm, new chlorophyll d-containing microorganisms were isolated from the living stromatolites (collected from Shark Bay, Western Australia) and red algae on mangrove pneumatophores (collected from the Georges River, Sydney, Australia) and enriched in KES+ seawater medium. Microscopic examination of the red-light enriched cultures confirmed that they are Acaryochloris-like cyanobacteria. Using cyanobacterial-specific 16S rRNA gene primers, we obtained almost full length sequences of 16S rDNA from the newly isolated Chl d-containing cyanobacteria. The sequences shared 98% identity with Acaryochloris marina MBIC11017. Interestingly, the strain isolated from stromatolites (designated as ssball1 strain) was more similar to Acaryochloris sp CR111A while the strain isolated from Georges River (designated as Mangrove1 strain) was more closely related to Acaryochloris sp CCMEE 5401, which was isolated from an inland lake, Salton Sea in California,. Pigment composition of the newly isolated strains were determined using HPLC, However, no obvious differences were noted. Chl d was the major photopigment while Chl a was present as a minor photopigment, about 2%3.5 % of the total chlorophyll.

Baird, ME, Ralph, PJ, Rizwi, F, Wild-Allen, K & Steven, ADL 2013, 'A dynamic model of the cellular carbon to chlorophyll ratio applied to a batch culture and a continental shelf ecosystem', LIMNOLOGY AND OCEANOGRAPHY, vol. 58, no. 4, pp. 1215-1226.
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A novel parameterization of the dynamical relationship between cellular carbon (C) and chlorophyll (Chl) is developed using a Chl synthesis term that includes the physiological status of the cell and the effect of packaging of pigments within cells. The geometric derivation highlights the non-linear relationship between Chl content and absorption due to the package effect. When parameterized for a generic 3 mm radius phytoplankton cell, the model reproduces the magnitude and daily variations of C: Chl and C: nitrogen ratios of the diatom Skeletonema costatum in published laboratory experiments. The parameterization is then applied in a three-dimensional biogeochemical model containing three phytoplankton classes in the coastal waters off southeast Tasmania, Australia, which demonstrates the behavior of the dynamic Chl parameterization over a range of light- and nutrient-limiting environments for phytoplankton of different sizes and growth rates. The model produces C: Chl ratios of , 1220 (weight : weight) and , 6080 for phytoplankton communities dominated by fast-growing small and fast-growing large cells, respectively, close to the ratios of 17 and 76 observed at two sampling stations during periods with diatom- and flagellate-dominated communities. Throughout the simulation, community C: Chl ratios generally vary between 12 and 200, which is similar to the range observed globally. In the new parameterization, C: Chl ratios are most influenced by the package effect for light-limited, slow-growing large microalgae, with physiological processes becoming important for smaller, nutrient-limited, fast-growing microalgae.

Behrendt, L, Staal, M, Cristescu, SM, Harren, FJM, Schliep, M, Larkum, AWD & Kühl, M 2013, 'Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina', F1000Research, vol. 2, pp. 44-44.
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Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared-radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance.

Brading, P, Warner, ME, Smith, DJ & Suggett, DJ 2013, 'Contrasting modes of inorganic carbon acquisition amongst Symbiodinium (Dinophyceae) phylotypes', New Phytologist, vol. 200, no. 2, pp. 432-442.
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SummaryGrowing concerns over ocean acidification have highlighted the need to critically understand inorganic carbon acquisition and utilization in marine microalgae. Here, we contrast these characteristics for the first time between two genetically distinct dinoflagellate species of the genus Symbiodinium (phylotypes A13 and A20) that live in symbiosis with reef‐forming corals.Both phylotypes were grown in continuous cultures under identical environmental conditions. Rubisco was measured using quantitative Western blots, and radioisotopic 14C uptake was used to characterize light‐ and total carbon dioxide (TCO2)‐dependent carbon fixation, as well as inorganic carbon species preference and external carbonic anhydrase activity.A13 and A20 exhibited similar rates of carbon fixation despite cellular concentrations of Rubisco being approximately four‐fold greater in A13. The uptake of CO2 over was found to support the majority of carbon fixation in both phylotypes. However, A20 was also able to indirectly utilize by first converting it to CO2 via external carbonic anhydrase.These results show that adaptive differences in inorganic carbon acquisition have evolved within the Symbiodinium genus, which thus carries fundamental impl...

Ceh, J, Kilburn, MR, Cliff, JB, Raina, J, van Keulen, M & Bourne, DG 2013, 'Nutrient cycling in early coral life stages: Pocillopora damicornis larvae provide their algal symbiont (Symbiodinium) with nitrogen acquired from bacterial associates', Ecology and Evolution, vol. 3, no. 8, pp. 2393-2400.
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AbstractThe waters surrounding coral reef ecosystems are generally poor in nutrients, yet their levels of primary production are comparable with those reported from tropical rain forests. One explanation of this paradox is the efficient cycling of nutrients between the coral host, its endosymbiotic alga Symbiodinium and a wide array of microorganisms. Despite their importance for the animals' fitness, the cycling of nutrients in early coral life stages and the initial establishment of partnerships with the microbes involved in these processes has received little scrutiny to date. Nitrogen is an essential but limited nutrient in coral reef ecosystems. In order to assess the early nutrient exchange between bacteria and corals, coral larvae of the species Pocillopora damicornis were incubated with two coral‐associated bacteria (Alteromonas sp., or Vibrio alginolyticus), prelabeled with the stable nitrogen isotope 15N. The incorporation and translocation of nitrogen from Vibrio‐ and Alteromonas bacteria into P. damicornis coral larvae and specifically into the coral‐symbiotic Symbiodinium were detected by nanoscale secondary ion mass spectrometry (NanoSIMS). A significant increase in the amount of enriched 15N (two to threefold compared to natural abundance) was observed in P. damicornis larvae within 8 h of incubation for both bacterial treatments (one‐way ANOVA, F5,53 = 18.03, P = 0.004 for Alteromonas sp. and

Červený, J, Sinetova, MA, Valledor, L, Sherman, LA & Nedbal, L 2013, 'Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142', Proceedings of the National Academy of Sciences, vol. 110, no. 32, pp. 13210-13215.
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The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program. We report identification of a temperature-dependent ultradian metabolic rhythm that controls the alternating oxygenic and microoxic processes of Cyanothece sp. ATCC 51142 under continuous high irradiance and in high CO 2 concentration. During the oxygenic photosynthesis phase, nitrate deficiency limited protein synthesis and CO 2 assimilation was directed toward glycogen synthesis. The carbohydrate accumulation reduced overexcitation of the photosynthetic reactions until a respiration burst initiated a transition to microoxic N 2 fixation. In contrast to the circadian clock, this ultradian period is strongly temperature-dependent: 17 h at 27 °C, which continuously decreased to 10 h at 39 °C. The cycle was expressed by an oscillatory modulation of net O 2 evolution, CO 2 uptake, pH, fluorescence emission, glycogen content, cell division, and culture optical density. The corresponding ultradian modulation was also observed in the transcription of nitrogenase-related nifB and nifH genes and in nitrogenase activities. We propose that the control by the newly identified metabolic cycle adds another rhythmic component to the circadian clock that reflects the true metabolic state depending on the actual...

Chejara, DR, Kondaveeti, S, Prasad, K & Siddhanta, AK 2013, 'Studies on the structure–property relationship of sodium alginate based thixotropic hydrogels', RSC Advances, vol. 3, no. 36, pp. 15744-15744.
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Clark, JS, Poore, AGB, Ralph, PJ & Doblin, MA 2013, 'POTENTIAL FOR ADAPTATION IN RESPONSE TO THERMAL STRESS IN AN INTERTIDAL MACROALGA', JOURNAL OF PHYCOLOGY, vol. 49, no. 4, pp. 630-639.
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Understanding responses of marine algae to changing ocean temperatures requires knowledge of the impacts of elevated temperatures and the likelihood of adaptation to thermal stress. The potential for rapid evolution of thermal tolerance is dependent on the levels of heritable genetic variation in response to thermal stress within a population. Here, we use a quantitative genetic breeding design to establish whether there is a heritable variation in thermal sensitivity in two populations of a habitat-forming intertidal macroalga, Hormosira banksii (Turner) Descaisne. Gametes from multiple parents were mixed and growth and photosynthetic performance were measured in the resulting embryos, which were incubated under control and elevated temperature (20°C and 28°C). Embryo growth was reduced at 28°C, but significant interactions between male genotype and temperature in one population indicated the presence of genetic variation in thermal sensitivity. Selection for more tolerant genotypes thus has the ability to result in the evolution of increased thermal tolerance. Furthermore, genetic correlations between embryos grown in the two temperatures were positive, indicating that those genotypes that performed well in elevated temperature also performed well in control temperature. Chlorophyll a fluorescence measurements showed a marked decrease in maximum quantum yield of photosystem II (PSII) under elevated temperature. There was an increase in the proportion of energy directed to photoinhibition (nonregulated nonphotochemical quenching) and a concomitant decrease in energy used to drive photochemistry and xanthophyll cycling (regulated nonphotochemical quenching). However, PSII performance between genotypes was similar, suggesting that thermal sensitivity is related to processes other than photosynthesis. © 2013 Phycological Society of America.

Dafforn, KA, Kelaher, BP, Simpson, SL, Coleman, MA, Hutchings, PA, Clark, GF, Knott, NA, Doblin, MA & Johnston, EL 2013, 'Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants', PLOS ONE, vol. 8, no. 9, pp. 1-10.
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Ecological communities are increasingly exposed to multiple chemical and physical stressors, but distinguishing anthropogenic impacts from other environmental drivers remains challenging. Rarely are multiple stressors investigated in replicated studies over large spatial scales (.1000 kms) or supported with manipulations that are necessary to interpret ecological patterns. We measured the composition of sediment infaunal communities in relation to anthropogenic and natural stressors at multiple sites within seven estuaries. We observed increases in the richness and abundance of polychaete worms in heavily modified estuaries with severe metal contamination, but no changes in the diversity or abundance of other taxa. Estuaries in which toxic contaminants were elevated also showed evidence of organic enrichment. We hypothesised that the observed response of polychaetes was not a `positive response to toxic contamination or a reduction in biotic competition, but due to high levels of nutrients in heavily modified estuaries driving productivity in the water column and enriching the sediment over large spatial scales. We deployed defaunated field-collected sediments from the surveyed estuaries in a small scale experiment, but observed no effects of sediment characteristics (toxic or enriching). Furthermore, invertebrate recruitment instead reflected the low diversity and abundance observed during field surveys of this relatively `pristine estuary. This suggests that differences observed in the survey are not a direct consequence of sediment characteristics (even severe metal contamination) but are related to parameters that covary with estuary modification such as enhanced productivity from nutrient inputs and the diversity of the local species pool. This has implications for the interpretation of diversity measures in large-scale monitoring studies in which the observed patterns may be strongly influenced by many factors that covary with anthropogenic modification.

Dennis, PG, Seymour, J, Kumbun, K & Tyson, GW 2013, 'Diverse populations of lake water bacteria exhibit chemotaxis towards inorganic nutrients', The ISME Journal, vol. 7, no. 8, pp. 1661-1664.
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Abstract Chemotaxis allows microorganisms to rapidly respond to different environmental stimuli; however, understanding of this process is limited by conventional assays, which typically focus on the response of single axenic cultures to given compounds. In this study, we used a modified capillary assay coupled with flow cytometry and 16S rRNA gene amplicon pyrosequencing to enumerate and identify populations within a lake water microbial community that exhibited chemotaxis towards ammonium, nitrate and phosphate. All compounds elicited chemotactic responses from populations within the lake water, with members of Sphingobacteriales exhibiting the strongest responses to nitrate and phosphate, and representatives of the Variovorax, Actinobacteria ACK-M1 and Methylophilaceae exhibiting the strongest responses to ammonium. Our results suggest that chemotaxis towards inorganic substrates may influence the rates of biogeochemical processes.

Exton, DA, Suggett, DJ, McGenity, TJ & Steinke, M 2013, 'Chlorophyll‐normalized isoprene production in laboratory cultures of marine microalgae and implications for global models', Limnology and Oceanography, vol. 58, no. 4, pp. 1301-1311.
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We used laboratory cultures of marine microalgae to investigate the effects of growth conditions and their taxonomic position on the production of isoprene, a gas that has major effects on atmospheric chemistry and provides stress tolerance to many primary producers. Isoprene was quantified from 21 microalgal strains sampled during exponential growth, using purge‐and‐trap pre‐concentration and gas chromatography with flame‐ionization detection. Isoprene production rates varied by two orders of magnitude between strains (0.03–1.34 µmol [g chlorophyll a]−1 h−1), and were positively correlated with temperature (r2 = 0.52, p < 0.001, n = 59). Three distinct sea surface temperature (SST)‐dependent relationships were found between isoprene and chlorophyll a (µmol [g chlorophyll a]−1 h−1), an improvement in resolution over the single relationship used in previous models: for three polar strains grown at −1°C (slope = 0.03, R2 = 0.76, p < 0.05, n = 9), nine strains grown at 16°C (slope = 0.24, R2 = 0.43, p < 0.05, n = 27 with Dunaliella tertiolecta excluded), and eight strains grown at 26°C (slope = 0.39, R2 = 0.15, p < 0.05, n = 24). We then used a simple model that applied the SST‐dependent nature of isoprene production to three representative bioregions for the growth temperatures used in this study. This approach yielded an est...

Garby, TJ, Walter, MR, Larkum, AWD & Neilan, BA 2013, 'Diversity of cyanobacterial biomarker genes from the stromatolites of Shark Bay, Western Australia', Environmental Microbiology, vol. 15, no. 5, pp. 1464-1475.
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SummaryFamilies of closely related chemical compounds, which are relatively resistant to degradation, are often used as biomarkers to help trace the evolutionary history of early groups of organisms and the environments in which they lived. Biomarkers derived from hopanoid variations are particularly useful in determining bacterial community compositions. 2‐Methylhopananoids have been thought to be diagnostic for cyanobacteria, and 2‐methylhopanes in the geological record are taken as evidence for the presence of cyanobacteria‐containing communities at the time of sediment deposition. Recently, however, doubt has been cast on the validity of 2‐methylhopanes as cyanobacterial biomarkers, since non‐cyanobacterial species have been shown to produce significant amounts of 2‐methylhopanoids. This study examines the diversity of hpnP, the hopanoid biosynthesis gene coding for the enzyme that methylates hopanoids at the C2 position. Genomic DNA isolated from stromatolite‐associated pustular and smooth microbial mat samples from Shark Bay, Western Australia, was analysed for bacterial diversity, and used to construct an hpnP clone library. A total of 117 partial hpnP clones were sequenced, representing 12 operational taxonomic units (OTUs). Phylogenetic analysis showed that 11 of these OTUs, representing 115 sequences, cluster within the cyanobacterial clade. We conclude that the dominant types of microorganisms with the detected capability of producing 2‐methylhopanoids within pustular and smooth microbial mats in Shark Bay are cyanobacteria.

Gleason, FH, van Ogtrop, F, Lilje, O & Larkum, AWD 2013, 'Ecological roles of zoosporic parasites in blue carbon ecosystems', Fungal Ecology, vol. 6, no. 5, pp. 319-327.
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Pathosystems describe the relationships between parasites, hosts and the environment. Generally these systems remain in a dynamic equilibrium over time. In this review we examine some of the evidence for the potential impacts of change in dynamic equilibrium in blue carbon ecosystems and the relationships to the amount of stored carbon. Blue carbon ecosystems are marine and estuarine ecosystems along the coasts. Virulent pathogens can be introduced into ecosystems along with non-native hosts. Alteration of environmental conditions, such as temperature, pH and salinity, may cause parasites to dominate the pathosystems resulting in significant decreases in productivity and population sizes of producer hosts and in changes in the overall species composition and function in these ecosystems. Such changes in blue carbon ecosystems may result in accelerated release of carbon dioxide back into the ocean and atmosphere, which could then drive further changes in the global climate. The resiliency of these ecosystems is not known. However, recent evidence suggests that significant proportions of blue carbon ecosystems have already disappeared.

Gobler, CJ, Lobanov, AV, Tang, Y-Z, Turanov, AA, Zhang, Y, Doblin, M, Taylor, GT, Sanudo-Wilhelmy, SA, Grigoriev, IV & Gladyshev, VN 2013, 'The central role of selenium in the biochemistry and ecology of the harmful pelagophyte, Aureococcus anophagefferens', ISME JOURNAL, vol. 7, no. 7, pp. 1333-1343.
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The trace element selenium (Se) is required for the biosynthesis of selenocysteine (Sec), the 21st amino acid in the genetic code, but its role in the ecology of harmful algal blooms (HABs) is unknown. Here, we examined the role of Se in the biology and ecology of the harmful pelagophyte, Aureococcus anophagefferens, through cell culture, genomic analyses and ecosystem studies. This organism has the largest and the most diverse selenoproteome identified to date that consisted of at least 59 selenoproteins, including known eukaryotic selenoproteins, selenoproteins previously only detected in bacteria, and novel selenoproteins. The A. anophagefferens selenoproteome was dominated by the thioredoxin fold proteins and oxidoreductase functions were assigned to the majority of detected selenoproteins. Insertion of Sec in these proteins was supported by a unique Sec insertion sequence. Se was required for the growth of A. anophagefferens as cultures grew maximally at nanomolar Se concentrations. In a coastal ecosystem, dissolved Se concentrations were elevated before and after A. anophagefferens blooms, but were reduced by 495% during the peak of blooms to 0.05 nM. Consistent with this pattern, enrichment of seawater with selenite before and after a bloom did not affect the growth of A. anophagefferens, but enrichment during the peak of the bloom significantly increased population growth rates. These findings demonstrate that Se inventories, which can be anthropogenically enriched, can support proliferation of HABs, such as A. anophagefferens through its synthesis of a large arsenal of Se-dependent oxidoreductases that fine-tune cellular redox homeostasis.

Gupta, V, Thakur, RS, Reddy, CRK & Jha, B 2013, 'Central metabolic processes of marine macrophytic algae revealed from NMR based metabolome analysis', RSC Advances, vol. 3, no. 19, pp. 7037-7037.
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Gupta, V, Trivedi, N, Kumar, M, Reddy, CRK & Jha, B 2013, 'Purification and characterization of exo-β-agarase from an endophytic marine bacterium and its catalytic potential in bioconversion of red algal cell wall polysaccharides into galactans', Biomass and Bioenergy, vol. 49, pp. 290-298.
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An extracellular exo-β-agarase was characterized from an endophytic bacterial strain Pseudomonas sp. isolated from the red alga Gracilaria dura. The enzyme was purified to homogeneity with a recovery of 28.2% and a purity fold of 8.33. The purified enzyme was composed of single polypeptide with a molecular mass of about 66 kDa. The enzyme exhibited a maximum activity of 81.74 U mL-1 and a specific activity of 615.5 U mg-1. The optimal pH and temperature for its maximum activity were 9.0 and 35 °C respectively. The enzyme stabilized its activity in alkaline pH 7-11 and high salt concentration up to 4 mol dm-3. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose while the bacterium when incubated with G. dura biomass yielded galactose 20% on dry wt basis. The agarolytic ability of the former was further confirmed by release of protoplasts from G. dura tissue through digestion of cell wall polysaccharides. The bacterium investigated in this study could possibly be used for bioconversion of marine red algal polysaccharides into energy feedstock and the purified enzyme for preparation of compounds having pharmaceutical importance. © 2013 Elsevier Ltd.

Gustafsson, MSM, Baird, ME & Ralph, PJ 2013, 'The interchangeability of autotrophic and heterotrophic nitrogen sources in Scleractinian coral symbiotic relationships: A numerical study', ECOLOGICAL MODELLING, vol. 250, pp. 183-194.
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The success of corals in tropical oligotrophic waters depends largely on their symbiotic relationship with the dinoflagellate algae residing in their tissues. Understanding the dynamics of this symbiosis is essential to predict how corals respond to environmental stressors, such as changes in nutrients availability, water temperatures and irradiance. This study presents a numerical model of the symbiotic relationship between a heterotrophic coral (cnidarian) host and autotrophic symbiotic dinoflagellates, including the major metabolic and physical functions of the system, under non-bleaching conditions. The coral acquires nitrogen (N) through two processes, uptake of dissolved inorganic nitrogen (VH DIN) and heterotrophic feeding (ZN). Numerical experiments were used to highlight the importance of these different sources of N for coral survival and growth. The model was analyzed for four external nutrient supply scenarios, using combinations of two VH DIN rates (high and low) and two ZN rates (high and low), and for a range of light levels. The model outputs showed the importance of the algae symbionts to the coral host as a source of both N and C when the feeding rate was limited, with heterotrophic feeding providing only 14% of the N needed to sustain the host biomass for the low ZN + high VH DIN scenario. In contrast, with no light or low light, conditions under which the symbiont population dies, the host was able to survive if ZN was high. Living inside the host the symbiont population thrived as long as there was enough light, as well as, DIN and DIC in the host tissues, independent of whether N was supplied as ZN or VH DIN. Translocation and recycling of nutrient were two of the most important features of this model, emphasizing why it is essential to resolve host and symbiont in a coral model. The model highlights that the interchangeability of N sources, and the ability to exchange and recycle nutrients in the host-symbiont system, is the key to coral su...

Hong, Y, Burford, MA, Ralph, PJ, Udy, JW & Doblin, MA 2013, 'The cyanobacterium Cylindrospermopsis raciborskii is facilitated by copepod selective grazing', HARMFUL ALGAE, vol. 29, no. 1, pp. 14-21.
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Blooms of the toxin-producing cyanobacterium Cylindrospermopsis raciborskii occur in tropical and subtropical lakes during spring-summer but the mechanisms behind bloom formation are unclear. This study tests the hypothesis that C. raciborskii accumulations in freshwater systems are facilitated by selective copepod grazing. Prey selection was examined in a series of experiments with C. raciborskii and the green alga, Chlamydomonas reinhardtii, as well as within natural phytoplankton assemblages. Clearance rates of the copepod Boeckella sp. on a C. raciborskii diet were 24 times lower than that of a common cladoceran Ceriodaphnia sp. when both grazers had prey choice. More C. raciborskii was cleared by Boeckella sp. when in mixed natural phytoplankton assemblages, but the clearance rate declined when nutrient replete C. reinhardtii was added, demonstrating that when alternate high quality algae were present, so did C. raciborskii consumption. The clearance rates of Boeckella sp. on two toxic C. raciborskii strains were significantly lower than on a non-toxic strain, and on C. raciborskii with low cellular P content. When we tested the grazing preference of a copepod dominated mixed zooplankton community on C. raciborskii during the early bloom period, clearance rates were relatively low (0.050.20 ml individual-1 h-1), and decreased significantly as the proportion of C. raciborskii increased above 5%. These results suggest that C. raciborskii persistence could be promoted by copepods preferentially grazing on other algae, with significant loss of top-down control as C. raciborskii abundance increases.

Koilraj, P, Antonyraj, CA, Gupta, V, Reddy, CRK & Kannan, S 2013, 'Novel approach for selective phosphate removal using colloidal layered double hydroxide nanosheets and use of residue as fertilizer', Applied Clay Science, vol. 86, pp. 111-118.
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Kondaveeti, S, Chejara, DR & Siddhanta, AK 2013, 'A facile one-pot synthesis of a fluorescent agarose-O-naphthylacetyl adduct with slow release properties', Carbohydrate Polymers, vol. 98, no. 1, pp. 589-595.
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Kondaveeti, S, Prasad, K & Siddhanta, AK 2013, 'Functional modification of agarose: A facile synthesis of a fluorescent agarose-tryptophan based hydrogel', Carbohydrate Polymers, vol. 97, no. 1, pp. 165-171.
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Kopp, C, Pernice, M, Domart-Coulon, I, Djediat, C, Spangenberg, JE, Alexander, DTL, Hignette, M, Meziane, T & Meibom, A 2013, 'Highly Dynamic Cellular-Level Response of Symbiotic Coral to a Sudden Increase in Environmental Nitrogen', mBio, vol. 4, no. 3.
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ABSTRACT Metabolic interactions with endosymbiotic photosynthetic dinoflagellate Symbiodinium spp. are fundamental to reef-building corals (Scleractinia) thriving in nutrient-poor tropical seas. Yet, detailed understanding at the single-cell level of nutrient assimilation, translocation, and utilization within this fundamental symbiosis is lacking. Using pulse-chase 15 N labeling and quantitative ion microprobe isotopic imaging (NanoSIMS; nanoscale secondary-ion mass spectrometry), we visualized these dynamic processes in tissues of the symbiotic coral Pocillopora damicornis at the subcellular level. Assimilation of ammonium, nitrate, and aspartic acid resulted in rapid incorporation of nitrogen into uric acid crystals (after ~45 min), forming temporary N storage sites within the dinoflagellate endosymbionts. Subsequent intracellular remobilization of this metabolite was accompanied by translocation of nitrogenous compounds to the coral host, starting at ~6 h. Within the coral tissue, nitrogen is utilized in specific cellular compartments in all four epithelia, including mucus chambers, Golgi bodies, and vesicles in calicoblastic cells. Our study shows how nitrogen-limited symbiotic corals take advantage of sudden changes in nitrogen availability; this opens new perspectives for functional studies of nutrient storage and remobilization in microbial symbioses in changing reef environments. IMPORTANCE The methodology applied, combining transmission electron microscopy with nanoscale secondary-ion mass spectrometry (NanoSIMS) imaging of coral tissue labeled with stable isotope tracers, allows quantification and submicrometric localization of metabolic fluxes in an intact s...

Kraemer, WE, Schrameyer, V, Hill, R, Ralph, PJ & Bischof, K 2013, 'PSII activity and pigment dynamics of Symbiodinium in two Indo-Pacific corals exposed to short-term high-light stress', MARINE BIOLOGY, vol. 160, no. 3, pp. 563-577.
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This study examined the capacity for photoprotection and repair of photo-inactivated photosystem II in the same Symbiodinium clade associated with two coexisting coral species during high-light stress in order to test for the modulation of the symbionts photobiological response by the coral host. After 4 days exposure to in situ irradiance, symbionts of the bleaching-sensitive Pocillopora damicornis showed rapid synthesis of photoprotective pigments (by 44 %) and strongly enhanced rates of xanthophyll cycling (by 446 %) while being insufficient to prevent photoinhibition (sustained loss in F v/F m at night) and loss of symbionts after 4 days. By contrast, Pavona decussata showed no significant changes in F v/F m, symbiont density or xanthophyll cycling. Given the association with the same Symbiodinium clade in both coral species, our findings suggest that symbionts in the two species examined may experience different in hospite light conditions as a result of different biometric properties of the coral host.

Krug, LA, Gherardi, DFM, Stech, JL, Leão, ZMAN, Kikuchi, RKP, Hruschka, ER & Suggett, DJ 2013, 'The construction of causal networks to estimate coral bleaching intensity', Environmental Modelling & Software, vol. 42, no. 1, pp. 157-167.
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Current metrics for predicting bleaching episodes, e.g. NOAA's Coral Reef Watch Program, do not seem to apply well to Brazil's marginal reefs located in Bahia state and alternative predictive approaches must be sought for effective long term management. Bleaching occurrences at Abrolhos have been observed since the 1990s but with a much lower frequency/extent than for other reef systems worldwide. We constructed a Bayesian Belief Network (BN) to back-predict the intensity of bleaching events and learn how local and regional scale forcing factors interact to enhance or alleviate coral bleaching specific to Abrolhos. Bleaching intensity data were collected for several reef sites across Bahia state coast (~12°-20°S; 37°-40°W) during the austral summer 1994-2005 and compared to environmental data: sea surface temperature (SST), diffuse light attenuation coefficient at 490 nm (K490), rain precipitation, wind velocities, and El Niño Southern Oscillation (ENSO) proxies. Conditional independence tests were calculated to produce four specialized BNs, each with specific factors that likely regulate bleaching intensity. All specialized BNs identified that a five-day accumulated SST proxy (SSTAc5d) was the exclusive parent node for coral bleaching producing a total predictive rate of 88% based on SSTAc5d state. When SSTAc5d was simulated as unknown, the Thermal-Eolic Resultant BN kept the total predictive rate of 88%. Our approach has produced initial means to predict beaching intensity at Abrolhos. However, the robustness of the model required for management purposes must be further (and regularly) operationally tested with new in situ and remote sensing data. © 2013 Elsevier Ltd.

Kuzhiumparambil, U & Fu, S 2013, 'Effect of hydrogen peroxide oxidation systems on human urinary steroid profiles', ANALYTICAL METHODS, vol. 5, no. 17, pp. 4402-4408.
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In sports drug testing the steroid profile is the most versatile and informative screening tool for the detection of steroid abuse. Despite the introduction of observed urine collection procedures by the World Anti-Doping Agency (WADA), chemical manipulation of urine specimens by athletes to conceal drug use still occurs and poses an ongoing challenge for doping control laboratories worldwide. In vitro urine adulteration using highly oxidative chemicals have been reported several times in the past. In this study we report the effect of two oxidising agents, Fenton's reagent and peroxidase-peroxide system on the human urinary steroid profile. Varying concentrations of these oxidants were reacted with urine and the reactions monitored by gas chromatography-mass spectrometry. A significant decrease in the absolute concentrations of androsterone, etiocholanolone, 5α-androstane-3α, 17β-diol, 5β-androstane-3α,17β-diol and epitestosterone was observed with consequent alteration of the steroid profile ratios. Adulteration of urine sample with these oxidants can thus mask the abnormality in a steroidal profile following steroid abuse. Drug testing authorities should take into account the effects of these oxidizing adulterants while interpreting the steroid profile data for doping control purposes. © The Royal Society of Chemistry.

Kuzhiumparambil, U & Fu, S 2013, 'Effect of oxidizing adulterants on human urinary steroid profiles', STEROIDS, vol. 78, no. 2, pp. 288-296.
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Steroid profiling is the most versatile and informative technique adapted by doping control laboratories for detection of steroid abuse. The absolute concentrations and ratios of endogenous steroids including testosterone, epitestosterone, androsterone, etiocholanolone, 5α-androstane-3α, 17β-diol and 5β-androstane-3α,17β-diol constitute the significant characteristics of a steroid profile. In the present study we report the influence of various oxidizing adulterants on the steroid profile of human urine. Gas chromatography-mass spectrometry analysis was carried out to develop the steroid profile of human male and female urine. Oxidants potassium nitrite, sodium hypochlorite, potassium permanganate, cerium ammonium nitrate, sodium metaperiodate, pyridinium chlorochromate, potassium dichromate and potassium perchlorate were reacted with urine at various concentrations and conditions and the effect of these oxidants on the steroid profile were analyzed. Most of the oxidizing chemicals led to significant changes in endogenous steroid profile parameters which were considered stable under normal conditions. These oxidizing chemicals can cause serious problems regarding the interpretation of steroid profiles and have the potential to act as masking agents that can complicate or prevent the detection of the steroid abuse. © 2012 Elsevier Inc. All rights reserved.

Lawrenz, E, Silsbe, G, Capuzzo, E, Ylöstalo, P, Forster, RM, Simis, SGH, Prášil, O, Kromkamp, JC, Hickman, AE, Moore, CM, Forget, M-H, Geider, RJ & Suggett, DJ 2013, 'Predicting the Electron Requirement for Carbon Fixation in Seas and Oceans', PLoS ONE, vol. 8, no. 3, pp. e58137-e58137.
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Marine phytoplankton account for about 50% of all global net primary productivity (NPP). Active fluorometry, mainly Fast Repetition Rate fluorometry (FRRf), has been advocated as means of providing high resolution estimates of NPP. However, not measuring CO2-fixation directly, FRRf instead provides photosynthetic quantum efficiency estimates from which electron transfer rates (ETR) and ultimately CO2-fixation rates can be derived. Consequently, conversions of ETRs to CO2-fixation requires knowledge of the electron requirement for carbon fixation (Φe,C, ETR/CO2 uptake rate) and its dependence on environmental gradients. Such knowledge is critical for large scale implementation of active fluorescence to better characterise CO2-uptake. Here we examine the variability of experimentally determined Φe,C values in relation to key environmental variables with the aim of developing new working algorithms for the calculation of Φe,C from environmental variables. Coincident FRRf and 14C-uptake and environmental data from 14 studies covering 12 marine regions were analysed via a meta-analytical, non-parametric, multivariate approach. Combining all studies, Φe,C varied between 1.15 and 54.2 mol e- (mol C)-1 with a mean of 10.9±6.91 mol e- mol C)-1. Although variability of Φe,C was related to environmental gradients at global scales, region-specific analyses provided far improved predictive capability. However, use of regional Φe,C algorithms requires objective means of defining regions of interest, which remains challenging. Considering individual studies and specific small-scale regions, temperature, nutrient and light availability were correlated with Φe,C albeit to varying degrees and depending on the study/region and the composition of the extant phytoplankton community. At the level of large biogeographic regions and distinct water masses, Φe,C was related to nutrient availability, chlorophyll, as well as temperature and/or salinity in most regions, while light...

McGinley, MP, Suggett, DJ & Warner, ME 2013, 'Transcript patterns of chloroplast‐encoded genes in cultured Symbiodinium spp. (Dinophyceae): testing the influence of a light shift and diel periodicity', Journal of Phycology, vol. 49, no. 4, pp. 709-718.
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Microalgae possess numerous cellular mechanisms specifically employed for acclimating the photosynthetic pathways to changes in the physical environment. Despite the importance of coral‐dinoflagellate symbioses, little focus has been given as to how the symbiotic algae (Symbiodinium spp.) regulate the expression of their photosynthetic genes. This study used real‐time PCR to investigate the transcript abundance of the plastid‐encoded genes, psbA (encoding the D1 protein of photosystem II) and psaA (encoding the P700 protein in photosystem I), within the cultured Symbiodinium ITS‐2 (internal transcribed spacer region) types A20 and A13. Transcript abundance was monitored during a low to high‐light shift, as well as over a full diel light cycle. In addition, psaA was characterized in three isolates (A20, A13, and D4‐5) and noted as another example of a dinoflagellate plastid gene encoded on a minicircle. In general, the overall incongruence of transcript patterns for both psbA and psaA between the Symbiodinium isolates and other models of transcriptionally controlled chloroplast gene expression (e.g., Pisum sativum [pea], Sinapis alba [mustard seedling], and Syne...

Mengoni, A, Focardi, A, Bacci, G & Ugolini, A 2013, 'High genetic diversity and variability of bacterial communities associated with the sandhopper Talitrus saltator (Montagu) (Crustacea, Amphipoda)', Estuarine, Coastal and Shelf Science, vol. 131, pp. 75-82.
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Mitchell, JG, Seuront, L, Doubell, MJ, Losic, D, Voelcker, NH, Seymour, J & Lal, R 2013, 'The Role of Diatom Nanostructures in Biasing Diffusion to Improve Uptake in a Patchy Nutrient Environment', PLoS ONE, vol. 8, no. 5, pp. e59548-e59548.
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Background Diatoms are important single-celled autotrophs that dominate most lit aquatic environments and are distinguished by surficial frustules with intricate designs of unknown function. Principal Findings We show that some frustule designs constrain diffusion to positively alter nutrient uptake. In nutrient gradients of 4 to 160 times over <5 cm, the screened-chambered morphology of Coscincodiscus sp. biases the nutrient diffusion towards the cell by at least 3.8 times the diffusion to the seawater. In contrast, the open-chambers of Thalassiosira eccentrica produce at least a 1.3 times diffusion advantage to the membrane over Coscincodiscus sp. when nutrients are homogeneous. Significance Diffusion constraint explains the success of particular diatom species at given times and the overall success of diatoms. The results help answer the unresolved question of how adjacent microplankton compete. Furthermore, diffusion constraint by supramembrane nanostructures to alter molecular diffusion suggests that microbes compete via supramembrane topology, a competitive mechanism not considered by the standard smooth-surface equations used for nutrient uptake nor in microbial ecology and cell physiology.

Mondal, AK, Su, D, Wang, Y, Chen, S & Wang, G 2013, 'Hydrothermal Synthesis of Nickel Oxide Nanosheets for Lithium-Ion Batteries and Supercapacitors with Excellent Performance', CHEMISTRY-AN ASIAN JOURNAL, vol. 8, no. 11, pp. 2828-2832.
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Nickel oxide nanosheets have been successfully synthesized by a facile ethylene glycol mediated hydrothermal method. The morphology and crystal structure of the nickel oxide nanosheets were characterized by X-ray diffraction, field-emission SEM, and TEM. When applied as electrode materials for lithium-ion batteries and supercapacitors, nickel oxide nanosheets exhibited a high, reversible lithium storage capacity of 1193 mA h g-1 at a current density of 500 mA g-1, an enhanced rate capability, and good cycling stability. Nickel oxide nanosheets also demonstrated a superior specific capacitance of 999 F g-1 at a current density of 20 A g-1 in supercapacitors. Between the sheets: NiO nanosheets were synthesized by a facile ethylene glycol mediated hydrothermal method (see picture). The NiO nanosheets exhibited a high, reversible lithium storage capacity of 1193 mA h g-1 at a current density of 500 mA g-1 for lithium-ion batteries and a superior specific capacitance of 999 F g-1 at a current density of 20 A g-1 in supercapacitors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mondal, D, Sharma, M, Mukesh, C, Gupta, V & Prasad, K 2013, 'Improved solubility of DNA in recyclable and reusable bio-based deep eutectic solvents with long-term structural and chemical stability', Chemical Communications, vol. 49, no. 83, pp. 9606-9606.
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Parker, L, Ross, P, O'Connor, W, Pörtner, H, Scanes, E & Wright, J 2013, 'Predicting the Response of Molluscs to the Impact of Ocean Acidification', Biology, vol. 2, no. 2, pp. 651-692.
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Elevations in atmospheric carbon dioxide (CO2) are anticipated to acidify oceans because of fundamental changes in ocean chemistry created by CO2 absorption from the atmosphere. Over the next century, these elevated concentrations of atmospheric CO2 are expected to result in a reduction of the surface ocean waters from 8.1 to 7.7 units as well as a reduction in carbonate ion (CO32−) concentration. The potential impact that this change in ocean chemistry will have on marine and estuarine organisms and ecosystems is a growing concern for scientists worldwide. While species-specific responses to ocean acidification are widespread across a number of marine taxa, molluscs are one animal phylum with many species which are particularly vulnerable across a number of life-history stages. Molluscs make up the second largest animal phylum on earth with 30,000 species and are a major producer of CaCO3. Molluscs also provide essential ecosystem services including habitat structure and food for benthic organisms (i.e., mussel and oyster beds), purification of water through filtration and are economically valuable. Even sub lethal impacts on molluscs due to climate changed oceans will have serious consequences for global protein sources and marine ecosystems.

Petrou, K, Jimenez-Denness, I, Chartrand, K, McCormack, C, Rasheed, M & Ralph, PJ 2013, 'Seasonal heterogeneity in the photophysiological response to air exposure in two tropical intertidal seagrass species', MARINE ECOLOGY PROGRESS SERIES, vol. 482, pp. 93-106.
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Photosynthesis, chlorophyll a fluorescence, leaf bio-optical properties and pigments were measured in 2 tropical intertidal seagrass species, Zostera muelleri ssp. capricorni and Halophila ovalis before, during and after air-exposure over a tidal cycle. Data were collected across 4 seasons (October and January-growing seasons; May and July-senescent seasons) to determine seasonal dynamics in physiological responses to air exposure. Both species showed clear light-dependent responses with a decline in photosynthetic efficiency and increased photoprotection during periods of combined maximum daily irradiance and air exposure for all seasons. In Z. muelleri ssp. capricorni there was a negative correlation between air-exposed effective quan - tum yield and light intensity, suggesting exposure was driving this decline. Conversely, sensitivity (decline in effective quantum yield of photosystem II) to increased irradiance dominated the response in H. ovalis, with no change in the magnitude of this response between air-exposed and submerged blades. The response to air exposure observed in Z. muelleri ssp. capricorni showed seasonal variation, with a greater decline in photosynthesis during the spring (October). Tidal exposure did not provide intertidal seagrasses a 'window' of photosynthetic respite (increase in photosynthesis) from high natural or anthropogenic turbidity. However, the periods immediately prior to and after exposure were important for providing an optimum period for net photosynthetic gain. © Inter-Research 2013.

Raina, J-B, Tapiolas, DM, Forêt, S, Lutz, A, Abrego, D, Ceh, J, Seneca, FO, Clode, PL, Bourne, DG, Willis, BL & Motti, CA 2013, 'DMSP biosynthesis by an animal and its role in coral thermal stress response', Nature, vol. 502, no. 7473, pp. 677-680.
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Globally, reef-building corals are the most prolific producers of dimethylsulphoniopropionate (DMSP)1,2, a central molecule in the marine sulphur cycle and precursor of the climate-active gas dimethylsulphide3,4. At present, DMSP production by corals is attributed entirely to their algal endosymbiont, Symbiodinium2. Combining chemical, genomic and molecular approaches, we show that coral juveniles produce DMSP in the absence of algal symbionts. DMSP levels increased up to 54% over time in newly settled coral juveniles lacking algal endosymbionts, and further increases, up to 76%, were recorded when juveniles were subjected to thermal stress. We uncovered coral orthologues of two algal genes recently identified in DMSP biosynthesis, strongly indicating that corals possess the enzymatic machinery necessary for DMSP production. Our results overturn the paradigm that photosynthetic organisms are the sole biological source of DMSP, and highlight the double jeopardy represented by worldwide declining coral cover, as the potential to alleviate thermal stress through coral-produced DMSP declines correspondingly.

Raven, JA, Beardall, J, Larkum, AWD & Sánchez-Baracaldo, P 2013, 'Interactions of photosynthesis with genome size and function', Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 368, no. 1622, pp. 20120264-20120264.
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Photolithotrophs are divided between those that use water as their electron donor (Cyanobacteria and the photosynthetic eukaryotes) and those that use a different electron donor (the anoxygenic photolithotrophs, all of them Bacteria). Photolithotrophs with the most reduced genomes have more genes than do the corresponding chemoorganotrophs, and the fastest-growing photolithotrophs have significantly lower specific growth rates than the fastest-growing chemoorganotrophs. Slower growth results from diversion of resources into the photosynthetic apparatus, which accounts for about half of the cell protein. There are inherent dangers in (especially oxygenic) photosynthesis, including the formation of reactive oxygen species (ROS) and blue light sensitivity of the water spitting apparatus. The extent to which photolithotrophs incur greater DNA damage and repair, and faster protein turnover with increased rRNA requirement, needs further investigation. A related source of environmental damage is ultraviolet B (UVB) radiation (280–320 nm), whose flux at the Earth's surface decreased as oxygen (and ozone) increased in the atmosphere. This oxygenation led to the requirements of defence against ROS, and decreasing availability to organisms of combined (non-dinitrogen) nitrogen and ferrous iron, and (indirectly) phosphorus, in the oxygenated biosphere. Differential codon usage in the genome and, especially, the proteome can lead to economies in the use of potentially growth-limiting elements

Roudnew, B, Lavery, TJ, Seymour, JR, Smith, RJ & Mitchell, JG 2013, 'Spatially varying complexity of bacterial and virus-like particle communities within an aquifer system', AQUATIC MICROBIAL ECOLOGY, vol. 68, no. 3, pp. 259-266.
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Hydrological and geological heterogeneity in the subsurface can isolate groundwater bodies in an aquifer system and create hydrologically distinct aquifers overlying each other with varying amounts of water exchange and unknown amounts of biological exchange. The heterogeneous nature of these subsurface waters likely drives changes in groundwater microbiological parameters. In the present study, flow cytometry was used to examine the abundance and cytometrically defined subpopulation structure of bacteria and virus-like particles (VLPs) in 3 distinct, vertically stratified aquifer layers consisting of an unconfined aquifer, a confining layer and a confined aquifer. Despite total microbial abundances remaining constant, the composition of bacterial and VLP communities varied among the aquifer layers. Cytometrically defined subpopulations were defined by nucleic acid content and size and ranged from 1 bacterial and VLP subpopulation in the unconfined aquifer to 4 bacterial and 3 VLP subpopulations in the confined aquifer. This variability in the subpopulation assemblages is likely driven by a combination of hydrological heterogeneity and biological interactions. The results presented here indicate complexity in microbial communities in discrete aquifer layers that may be overlooked when reporting general abundances. Groundwater bacteria and VLPs appear to be a sensitive indicator of the biological dynamics of aquifer systems and may be used to identify heterogeneous water bodies and help distinguish individual aquifer layers in an aquifer system.

Sackett, O, Petrou, K, Reedy, B, De Grazia, A, Hill, R, Doblin, M, Beardall, J, Ralph, P & Heraud, P 2013, 'Phenotypic Plasticity of Southern Ocean Diatoms: Key to Success in the Sea Ice Habitat?', PLOS ONE, vol. 8, no. 11.
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Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata) exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species' known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem. © 2013 Sackett et al.

SCHLIEP, M, CAVIGLIASSO, G, QUINNELL, RG, STRANGER, R & LARKUM, AWD 2013, 'Formyl group modification of chlorophyll a: a major evolutionary mechanism in oxygenic photosynthesis', Plant, Cell & Environment, vol. 36, no. 3, pp. 521-527.
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ABSTRACTWe discuss recent advances in chlorophyll research in the context of chlorophyll evolution and conclude that some derivations of the formyl side chain arrangement of the porphyrin ring from that of the Chl a macrocycle can extend the photosynthetic active radiation (PAR) of these molecules, for example, Chl d and Chl f absorb light in the near‐infrared region, up to ∼750 nm. Derivations such as this confer a selective advantage in particular niches and may, therefore, be beneficial for photosynthetic organisms thriving in light environments with particular light signatures, such as red‐ and near‐far‐red light‐enriched niches. Modelling of formyl side chain substitutions of Chl a revealed yet unidentified but theoretically possible Chls with a distinct shift of light absorption properties when compared to Chl a.

Siddhanta, AK, Kumar, S, Mehta, GK, Chhatbar, MU, Oza, MD, Sanandiya, ND, Chejara, DR, Godiya, CB & Kondaveeti, S 2013, 'Cellulose Contents of Some Abundant Indian Seaweed Species', Natural Product Communications, vol. 8, no. 4, pp. 1934578X1300800-1934578X1300800.
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Crude cellulose as well as α- and β-celluloses were estimated in thirty-four seaweed species of fifteen orders of Chlorophyta, Phaeophyta and Rhodophyta of Indian waters. The greatest yields of crude cellulose and α-cellulose were obtained from Chaetomorpha aerea (approx. 20.0% and 18.5%, respectively), and of β-cellulose (approx. 3.1%) from Caulerpa imbricata. The lowest crude cellulose, and α-and β-contents were recorded for the calcareous red alga Liagora indica (approx. 0.90%, 0.70% and 0.10%, respectively). There was little variation in cellulose content among the brown algae, while wide variations in the yields were found in the green and red algae. The present work contributes to the repertoire of 67 Indian seaweed species studied to now for their cellulose contents in our laboratory. The combined studies highlight that Chaetomorpha aerea, Acrosiphonia orientalis, Caulerpa taxifolia, Sargassum tenerrimum, Hydroclathrus clathratus and Gelidiella acerosa possess relatively high (>10%) cellulose contents, which could be of potential utility.

Sinutok, S, Hill, R, Doblin, MA & Ralph, PJ 2013, 'Diurnal photosynthetic response of the motile symbiotic benthic foraminiferan Marginopora vertebralis', MARINE ECOLOGY PROGRESS SERIES, vol. 478, pp. 127-138.
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Movement of the symbiont-bearing foraminiferan Marginopora vertebralis and photo physiological response to diurnal fluctuations in irradiance were investigated in field and laboratory experiments. The abundance of M. vertebralis from both light-exposed and sheltered habitats was determined 5 times during the day, from pre-dawn to post-dusk. M. vertebralis abundance was significantly higher in sheltered compared to exposed habitats at midday under high irradiance, and this movement enabled the algal symbionts to avoid excessive photoinhibition. The diurnal changes in photosynthetic efficiency were not consistent with the typical midday solar maximum downregulation of photosystem II observed in other photoautotrophs and was likely due to the negatively phototactic capacity of the foraminifera. To confirm the light-dependent movement of foraminifera, individuals in exposed and sheltered habitats were exposed to the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) in the laboratory. The lack of movement in DCMU-exposed specimens confirmed light-dependent movement and subsequent disruption of signalling between the host foraminiferan and the algal symbionts. Analysis of chlorophyll and xanthophyll pigments, as well as symbiont density, indicated that under high irradiance, foraminiferal symbionts have the capacity to reduce light stress by activating photoprotective mechanisms. The negatively phototactic behaviour prevented chlorophyll degradation, symbiont loss and bleaching, suggesting that it is the primary mechanism for controlling light exposure in these foraminifera. This behaviour provides a competitive advantage over other sessile organisms in avoiding photoinhibition and bleaching by moving away from over-saturating irradiance, towards less damaging light fields. © Inter-Research 2013.

Smith, RJ, Jeffries, TC, Roudnew, B, Seymour, JR, Fitch, AJ, Simons, KL, Speck, PG, Newton, K, Brown, MH & Mitchell, JG 2013, 'Confined aquifers as viral reservoirs', ENVIRONMENTAL MICROBIOLOGY REPORTS, vol. 5, no. 5, pp. 725-730.
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Knowledge about viral diversity and abundance in deep groundwater reserves is limited. We found that the viral community inhabiting a deep confined aquifer in South Australia was more similar to reclaimed water communities than to the viral communities in the overlying unconfined aquifer community. This similarity was driven by high relative occurrence of the single-stranded DNA viral groups Circoviridae, Geminiviridae and Microviridae, which include many known plant and animal pathogens. These groups were present in a 1500-year-old water situated 80?m below the surface, which suggests the potential for long-term survival and spread of potentially pathogenic viruses in deep, confined groundwater. Obtaining a broader understanding of potentially pathogenic viral communities within aquifers is particularly important given the ability of viruses to spread within groundwater ecosystems.

Suggett, DJ, Dong, LF, Lawson, T, Lawrenz, E, Torres, L & Smith, DJ 2013, 'Light availability determines susceptibility of reef building corals to ocean acidification', Coral Reefs, vol. 32, no. 2, pp. 327-337.
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Elevated seawater pCO2, and in turn ocean acidification (OA), is now widely acknowledged to reduce calcification and growth of reef building corals. As with other environmental factors (e. g., temperature and nutrients), light availability fundamentally regulates calcification and is predicted to change for future reef environments alongside elevated pCO2 via altered physical processes (e. g., sea level rise and turbidity); however, any potential role of light in regulating the OA-induced reduction of calcification is still unknown. We employed a multifactorial growth experiment to determine how light intensity and pCO2 together modify calcification for model coral species from two key genera, Acropora horrida and Porites cylindrica, occupying similar ecological niches but with different physiologies. We show that elevated pCO2 (OA)-induced losses of calcification in the light (GL) but not darkness (GD) were greatest under low-light growth conditions, in particular for A. horrida. High-light growth conditions therefore dampened the impact of OA upon GL but not GD. Gross photosynthesis (PG) responded in a reciprocal manner to GL suggesting OA-relieved pCO2 limitation of PG under high-light growth conditions to effectively enhance GL. A multivariate analysis of past OA experiments was used to evaluate whether our test species responses were more widely applicable across their respective genera. Indeed, the light intensity for growth was identified as a significant factor influencing the OA-induced decline of calcification for species of Acropora but not Porites. Whereas low-light conditions can provide a refuge for hard corals from thermal and light stress, our study suggests that lower light availability will potentially increase the susceptibility of key coral species to OA. © 2012 Springer-Verlag Berlin Heidelberg.

Tapiolas, DM, Raina, J-B, Lutz, A, Willis, BL & Motti, CA 2013, 'Direct measurement of dimethylsulfoniopropionate (DMSP) in reef-building corals using quantitative nuclear magnetic resonance (qNMR) spectroscopy', Journal of Experimental Marine Biology and Ecology, vol. 443, pp. 85-89.
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Reef building corals are among the largest producers of dimethylsulfoniopropionate (DMSP), a sulfur molecule synthesized by their endosymbiotic dinoflagellates in the genus Symbiodinium. DMSP is potentially involved in important physiological and ecological processes in corals, but investigating the functional role of this molecule requires rapid and accurate quantification techniques. Here we introduce a simple method enabling direct quantification of DMSP and one of its breakdown products acrylate using quantitative nuclear magnetic resonance (qNMR) spectroscopy. The method was tested on a range of coral genera and presents a number of advantages over currently used quantification techniques, including simultaneous and direct quantification of multiple molecules from the same extract, and rapid processing with high reproducibility enabling analyses of large numbers of samples in short time periods. The method was successfully applied to environmental samples and provides the first baseline information on diel variation of DMSP and acrylate concentrations in the coral Acropora millepora.

Trivedi, N, Gupta, V, Reddy, CRK & Jha, B 2013, 'Detection of ionic liquid stable cellulase produced by the marine bacterium Pseudoalteromonas sp. isolated from brown alga Sargassum polycystum C. Agardh', Bioresource Technology, vol. 132, pp. 313-319.
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Trivedi, N, Gupta, V, Reddy, CRK & Jha, B 2013, 'Enzymatic hydrolysis and production of bioethanol from common macrophytic green alga Ulva fasciata Delile', Bioresource Technology, vol. 150, pp. 106-112.
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Wong, ACK, Remin, R, Love, R, Aldred, R, Ralph, P & Cook, C 2013, 'Building Pedagogical Community in the Classroom', Christian Higher Education, vol. 12, no. 4, pp. 282-295.
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Ye, Z, Suggett, DJ, Robakowski, P & Kang, H 2013, 'A mechanistic model for the photosynthesis–light response based on the photosynthetic electron transport of photosystem II in C₃ and C₄ species', New Phytologist, vol. 199, no. 1, pp. 110-120.
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SummaryA new mechanistic model of the photosynthesis–light response is developed based on photosynthetic electron transport via photosystem II (PSII) to specifically describe light‐harvesting characteristics and associated biophysical parameters of photosynthetic pigment molecules. This model parameterizes ‘core’ characteristics not only of the light response but also of difficult to measure physical parameters of photosynthetic pigment molecules in plants.Application of the model to two C3 and two C4 species grown under the same conditions demonstrated that the model reproduced extremely well (r2 > 0.992) the light response trends of both electron transport and CO2 uptake.In all cases, the effective absorption cross‐section of photosynthetic pigment molecules decreased with increasing light intensity, demonstrating novel operation of a key mechanism for plants to avoid high light damage.In parameterizing these previously difficult to measure characteristics of light harvesting in higher plants, the model provides a new means to understand the mechanistic processes underpinning variability of CO2 uptake, for example, photosynthetic down‐regulation or reversible photoinhibition induced by high light and photoprotection. However, an important next step is validating this parameterization, possibly through application to less structurally complex ...

Ye, Z-P, Robakowski, P & Suggett, DJ 2013, 'A mechanistic model for the light response of photosynthetic electron transport rate based on light harvesting properties of photosynthetic pigment molecules', Planta, vol. 237, no. 3, pp. 837-847.
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Models describing the light response of photosynthetic electron transport rate (ETR) are routinely used to determine how light absorption influences energy, reducing power and yields of primary productivity; however, no single model is currently able to provide insight into the fundamental processes that implicitly govern the variability of light absorption. Here we present development and application of a new mechanistic model of ETR for photosystem II based on the light harvesting (absorption and transfer to the core 'reaction centres') characteristics of photosynthetic pigment molecules. Within this model a series of equations are used to describe novel biophysical and biochemical characteristics of photosynthetic pigment molecules and in turn light harvesting; specifically, the eigen-absorption cross-section and the minimum average lifetime of photosynthetic pigment molecules in the excited state, which describe the ability of light absorption of photosynthetic pigment molecules and retention time of excitons in the excited state but are difficult to be measured directly. We applied this model to a series of previously collected fluorescence data and demonstrated that our model described well the light response curves of ETR, regardless of whether dynamic down-regulation of PSII occurs, for a range of photosynthetic organisms (Abies alba, Picea abies, Pinus mugo and Emiliania huxleyi). Inherent estimated parameters (e. g. maximum ETR and the saturation irradiance) by our model are in very close agreement with the measured data. Overall, our mechanistic model potentially provides novel insights into the regulation of ETR by light harvesting properties as well as dynamical down-regulation of PSII. © 2012 Springer-Verlag Berlin Heidelberg.

York, PH, Gruber, RK, Hill, R, Ralph, PJ, Booth, DJ & Macreadie, PI 2013, 'Physiological and Morphological Responses of the Temperate Seagrass Zostera muelleri to Multiple Stressors: Investigating the Interactive Effects of Light and Temperature', PLOS ONE, vol. 8, no. 10.
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Understanding how multiple environmental stressors interact to affect seagrass health (measured as morphological and physiological responses) is important for responding to global declines in seagrass populations. We investigated the interactive effects of temperature stress (24, 27, 30 and 32°C) and shading stress (75, 50, 25 and 0% shade treatments) on the seagrass Zostera muelleri over a 3-month period in laboratory mesocosms. Z. muelleri is widely distributed throughout the temperate and tropical waters of south and east coasts of Australia, and is regarded as a regionally significant species. Optimal growth was observed at 27°C, whereas rapid loss of living shoots and leaf mass occurred at 32°C. We found no difference in the concentration of photosynthetic pigments among temperature treatments by the end of the experiment; however, up-regulation of photoprotective pigments was observed at 30°C. Greater levels of shade resulting in high photochemical efficiencies, while elevated irradiance suppressed effective quantum yield (ΔF/FM'). Chlorophyll fluorescence fast induction curves (FIC) revealed that the J step amplitude was significantly higher in the 0% shade treatment after 8 weeks, indicating a closure of PSII reaction centres, which likely contributed to the decline in ΔF/FM' and photoinhibition under higher irradiance. Effective quantum yield of PSII (ΔF/FM') declined steadily in 32°C treatments, indicating thermal damage. Higher temperatures (30°C) resulted in reduced above-ground biomass ratio and smaller leaves, while reduced light led to a reduction in leaf and shoot density, above-ground biomass ratio, shoot biomass and an increase in leaf senescence. Surprisingly, light and temperature had few interactive effects on seagrass health, even though these two stressors had strong effects on seagrass health when tested in isolation. In summary, these results demonstrate that populations of Z. muelleri in south-eastern Australia are sensitive to...

Howes, JM, Stuart, BH & Ralph, PJ 1970, 'Assessing metabolic variation of endosymbiotic and cultured Symbiodinium microadriaticum using synchrotron imaging FTIR spectroscopy', 7th International Workshop on Infrared Microscopy and Spectroscopy with Accelerator-Based Sources Abstracts, 7th International Workshop on Infrared Microscopy and Spectroscopy with Accelerator-Based Sources.

Howes, M, Stuart, BH & Ralph, PJ 1970, 'MACROMOLECULAR COMPOSITION VARIES SIGNIFICANTLY BETWEEN GENETIC CLADES OF SYMBIODINIUM MICROADRIATICUM', PHYCOLOGIA, 10th International Phycological Congress, pp. 46-47.

Klement, M, Šafránek, D, Děd, T, Pejznoch, A, Nedbal, L, Steuer, R, Červený, J & Müller, S 1970, 'A Comprehensive Web-based Platform For Domain-Specific Biological Models', Electronic Notes in Theoretical Computer Science, Elsevier BV, pp. 61-67.
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A Comprehensive Modeling Platform, that is, a general framework for public sharing, annotation, and visualization of domain-specific biological models, is presented. For a selected organism, the framework is instantiated as a web-based application which allows to capture several aspects of biological models represented as biochemical reaction networks or ordinary differential equations. The key feature of the instantiation for a given organism relies on mapping kinetic models to a precise textual and a schematic graphical representation of the related biological knowledge, thereby supporting the systems biological view of the modeled organism. Besides model repository and annotation, the platform includes basic model analysis features such as simulation and static analysis. © 2013 Elsevier B.V.

Blount, C, Alderson, B, Roberts, C, Cummings, D, Pernice, M & Neilson, J 2013, Bimonthly Coral Monitoring Report: Dredging Baseline Report − Ichthys Nearshore Environmental Monitoring Program, pp. 1-258, Sydney.

Blount, C, Roberts, C, Cummings, D, Pernice, M, Neilson, J & Nicastro, A 2013, Bimonthly Coral Monitoring Report: Dredging Report 2 − Ichthys Nearshore Environmental Monitoring Program, no. 2, pp. 1-126, Sydney.

Pernice, M, Roberts, C & Nicastro, A 2013, Bimonthly Coral Monitoring Report: Dredging Report 5 − Ichthys Nearshore Environmental Monitoring Program., no. 5, pp. 1-204, Sydney.

Ralph, PJ & Sinutok, S AccessUTS Pty Limited 2013, Vallisneria and submerged macrophyte management in Penrith Lakes, Sydney.

Ralph, PJ, Skilbeck, G & Sinutok, S AccessUTS Pty Limited 2013, Vallisneria and submerged macrophyte management in the Penrith Lakes Scheme, Sydney.

Roberts, C, Pernice, M & Nicastro, A 2013, Bimonthly Coral Monitoring Report: Dredging Report 3 − Ichthys Nearshore Environmental Monitoring Program., no. 3, pp. 1-154, Sydney.

Roberts, C, Pernice, M & Nicastro, A 2013, Bimonthly Coral Monitoring Report: Dredging Report 4 − Ichthys Nearshore Environmental Monitoring Program., no. 4, pp. 1-177, Sydney.