Cai, Z-L, Zeng, H, Chen, M & Larkum, AWD 2002, 'Raman spectroscopy of chlorophyll d from Acaryochloris marina', Biochimica et Biophysica Acta (BBA) - Bioenergetics, vol. 1556, no. 2-3, pp. 89-91.
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Chen, M, Quinnell, RG & Larkum, AWD 2002, 'Chlorophylldas the major photopigment inAcaryochloris marina', Journal of Porphyrins and Phthalocyanines, vol. 06, no. 12, pp. 763-773.
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Chlorophyll (Chl) d is the major pigment in the photosystems (PS) and light-harvesting complex(es) of Acaryochloris marina. Chl a is present in small and variable amounts in PSII and in the light-harvesting complex(es). Isolated PSII complex showed a major fluorescence emission peak at 725 nm and a smaller emission peak due to Chl d at 701 nm, while the PSI complex showed two pools of Chl d, one with emission at 730 nm and the other at 709 nm at 77 K. In PSI and PSII of classical cyanobacteria and of higher plants, where Chl a is the predominant pigment rather than Chl d, these differences are not as pronounced. Light energy absorbed by phycobiliproteins was also active in these Chl d emissions. The major light-harvesting pigment protein is similar to the prochlorophyte Chl-binding protein (pcb) and had a major emission peak at 711 nm. In Cyanobacteria an iron-stress induced Chl-binding protein (isiA) forms a polymeric ring around PSI, and so the effect(s) of iron stress on A. marina where investigated. No clear evidence could be deduced for the formation of an isiA protein under iron stress and no clear changes in the proportion of Chl d :Chl a could be discerned although phycobilins showed a decreased under iron-stress conditions. That Chl d replaces Chl a in all its functions in A. marina is clear; the advantage of this evolutionary development appears to be to enable A. marina to absorb far-red light which occurs in environments where red light is filtered out by other photosynthetic organisms.
Chen, M, Quinnell, RG & Larkum, AWD 2002, 'The major light‐harvesting pigment protein of Acaryochloris marina', FEBS Letters, vol. 514, no. 2-3, pp. 149-152.
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The major light‐harvesting protein complex containing chlorophyll (Chl) d was isolated from Acaryochloris marina thylakoid membranes. Isolation was achieved by detergent solubilisation followed by separation on 6–40% sucrose gradients using ultracentrifugation. The best Chl d yield (70%) used 0.3% dodecyl maltoside, 0.15% octyl glucoside, 0.05% zwittergent 3‐14 with the detergent:total Chl d ratio around 10:1 (w/w). Characterisation of the light‐harvesting pigment protein complex (lhc) involved non‐denaturing electrophoresis, SDS–PAGE, absorbance and fluorescence spectroscopy. The main polypeptide in the lhc was shown to be ca. 34 kDa and to contain Chl d and Chl a, indicating that the Acaryochloris lhc is similar to that of prochlorophytes. The Chl a level varied with the culture conditions, which is consistent with previous findings.
Gore, RB, Hadi, EA, Craven, M, Smillie, FI, O'Meara, TJ, Tovey, ER, Woodcock, A & Custovic, A 2002, 'Personal exposure to house dust mite allergen in bed: nasal air sampling and reservoir allergen levels', Clinical & Experimental Allergy, vol. 32, no. 6, pp. 856-859.
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SummaryBackground Assessment of personal exposure to dust mite allergen has relied on proxy measures. Only recently has a means to directly measure inhaled allergen particle number become available (the intra‐nasal air sampler).Objective To quantify inspired dust mite group 1 and group 2 allergen‐bearing particles in bed in undisturbed conditions prior to sleep by nasal air sampling and to investigate the relationship between inhaled particles and reservoir allergen levels.Methods Twelve volunteers wore nasal samplers in bed for 6 evenings, nose‐breathing in undisturbed conditions. Allergen‐bearing particles (‘halos’) were detected by immunostaining for Der p 1, Der p 2, or Der p 1 and Der p 2 together, and counted by light microscopy. Count data were square root transformed for analysis of variance. Mattress dust samples were assayed for Der p 1 and Der p 2 concentrations.Results Square root detransformed mean particle counts per 30‐min sample were: Der p 1, 4.22; Der p 2, 5.9; Der p 1 + Der p 2, 4.87; and for all samples, 5.01, with no difference between the groups. With replicate samples, halo number correlated significantly with mattress allergen concentrations (Der p 1 r = 0.80, P < 0.01; Der p 2 r = 0.68, P < 0.02).Conclusion Nasal air sampling can be used to quantify nocturnal Der p exposure in undisturbed conditions in an area with moderate exposure to mite allergen and can provide a direct measure of inhaled mite allergen. The choice of either Der p 1 or Der p 2 is appropriate for this purpose.
Laroussi, M, Dobbs, FC, Wei, Z, Doblin, MA, Ball, LG, Moreira, KR, Dyer, FF & Richardson, JP 2002, 'Decontamination of water by excimer UV radiation', IEEE TRANSACTIONS ON PLASMA SCIENCE, vol. 30, no. 4, pp. 1501-1503.
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Water is one of the most important substances on which life depends. However, water may also serve as a medium by which disease is spread to humans, animals, and plants. Therefore, the biological decontamination of this vital substance is of paramount im
Longstaff, BJ, Kildea, T, Runcie, JW, Cheshire, A, Dennison, WC, Hurd, C, Kana, T, Raven, JA & Larkum, AWD 2002, 'An in situ study of photosynthetic oxygen exchange and electron transport rate in the marine macroalga Ulva lactuca (Chlorophyta)', Photosynthesis Research, vol. 74, no. 3, pp. 281-293.
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Poulos, LM, O'Meara, TJ, Hamilton, RG & Tovey, ER 2002, 'Inhaled latex allergen (Hev b 1)', Journal of Allergy and Clinical Immunology, vol. 109, no. 4, pp. 701-706.
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BACKGROUND:IgE-mediated responses to natural rubber latex allergens have become a major health problem among recognized risk groups. OBJECTIVE:The purpose of this investigation was to measure the amounts of Hevea brasiliensis latex allergen (Hev b 1) inhaled and deposited on surfaces when latex or vinyl gloves were worn and compare the results with the conventional measures (breathing zone samplers) of occupational exposure. METHODS:Hev b 1 exposure was measured by nasal sampling and breathing zone sampling. Latex allergen exposure was generated by having each subject don a pair of powdered latex examination gloves and continuing his or her normal daily activity for 30 minutes. By means of adhesive tape, surface dust samples were collected from the surfaces of gloves, the subject's hands, and work areas. Sampling was performed with subjects wearing no gloves, subjects wearing powdered vinyl gloves, subjects wearing powdered latex gloves, and nearby colleagues wearing latex gloves. All samples were assayed through use of the HALOgen assay (Inhalix, Sydney, Australia) with a Hev b 1-specific mAb. Particles transporting latex allergen were identified by a surrounding immunostain halo, and these were quantified and reported as total numbers of particles inhaled, airborne, or found on surface areas evaluated. RESULTS:Study subjects inhaled 26 times more allergen when powdered latex gloves were worn than under the "no glove" and powdered vinyl glove conditions. During the same period, Hev b 1 particle levels measured in the ambient air through use of the breathing zone sampler increased by 24-fold. The median numbers of particles carrying Hev b 1 allergen per square centimeter on the surface of the hands after the wearing of latex and vinyl gloves were 1964 and 5, respectively. Latex allergen was physically associated both with cornstarch granules and with larger dust particles having a darker, more irregular appearance. CONCLUSION:In a laboratory where gloves are worn...
Ralph, PJ & Short, FT 2002, 'Impact of the wasting disease pathogen, Labyrinthula zosterae, on the photobiology of eelgrass Zostera marina', MARINE ECOLOGY PROGRESS SERIES, vol. 226, no. N/A, pp. 265-271.
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Labyrinthula zosterae is clearly shown to be a primary pathogen of eelgrass Zostera marina L., not merely a secondary infection of senescent leaves or an indication of decomposition, The results of this investigation using a Diving-PAM fluorometer indicate that the regions of tissue photosynthetically compromised by Labyrinthula are substantially larger than previously thought. Labyrinthula moves through Zostera marine tissue at a rate of up to 0.8 h-1 during daylight periods. The photosynthetic efficiency of apparently healthy green leaf tissue can be reduced by almost 50% in areas up to 3 mm from a necrotic region infected with Labyrinthula. Once a necrotic spot expands to bisect the eelgrass leaf, the condition of all acropertal tissue diminished; lead tissue up to 5 cm away has severely reduced photosynthetic activity.
Ralph, PJ, Gademann, R, Larkum, AWD & Kuhl, M 2002, 'Spatial heterogeneity in active chlorophyll fluorescence and PSII activity of coral tissues', MARINE BIOLOGY, vol. 141, no. 4, pp. 639-646.
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Chlorophyll-a fluorescence was measured in six species of coral, using pulse-amplitude-modulated fluorometers employing fibre-optic probes with diameters of 8 mm, 1 mm and 140 μm. The 8-mm probe integrated responses over a large area, giving more weight to coenosarc than polyp tissue for Acropora nobilis. With 1-mm and 140-μm fibre-optic probes, the photosynthetic responses of zooxanthellae in the coenosarc and the polyp tissue of Acropora nobilis were distinguished. The polyp tissue exhibited a lower maximum in relative electron transport rate than did the coenosarc tissue, and was subject to down-regulation at higher irradiances. Coenosarc and polyp tissue (both containing zooxanthellae) showed a wide range of responses in the other corals. Down-regulation of photosynthesis in a single polyp of Pocillopora damicornis was followed after exposure to moderate irradiance, with recovery occurring over a further 4 h of shade conditions. All the corals (Acropora millepora, A. nobilis, Cyphastrea serailia, Montipora tuberculosa, Pocillopora damicornis and Porites cylindrica) showed evidence of strong down-regulation of photosynthesis under high irradiance, and little evidence of photoinhibitory damage to photosystem II.
Ralph, PJ, Polk, SM, Moore, KA, Orth, RJ & Smith, WO 2002, 'Operation of the xanthophyll cycle in the seagrass Zostera marina in response to variable irradiance', JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, vol. 271, no. 2, pp. 189-207.
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Changes in the photobiology and photosynthetic pigments of the seagrass Zostera marina from Chesapeake Bay (USA) were examined under a range of natural and manipulated irradiance regimes. Photosynthetic activity was assessed using chlorophyll-a fluorescence, and photosynthetic pigments were measured by HPLC. Large changes in the violaxanthin, zeaxanthin, and antheraxanthin content were concomitant with the modulation of non-photochemical quenching (NPQ). Photokinetics (Fv/Fm, rapid light curves (RLC), and non-photochemical quenching) varied as a result of oscillating irradiance and were highly correlated to xanthophyll pigment content. Zeaxanthin and antheraxanthin concentrations increased under elevated light conditions, while violaxanthin increased in darkened conditions. Unusually high concentrations of antheraxanthin were found in Z. marina under a wide range of light conditions, and this was associated with the partial conversion of violaxanthin to zeaxanthin. These results support the idea that xanthophyll intermediate pigments induce a photoprotective response during exposure to high irradiances in this seagrass.
Schreiber, U, Gademann, R, Bird, P, Ralph, PJ, Larkum, AWD & Kuhl, M 2002, 'Apparent light requirement for activation of photosynthesis upon rehydration of desiccated beachrock microbial mats', JOURNAL OF PHYCOLOGY, vol. 38, no. 1, pp. 125-134.
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Photosynthetic electron transport of beachrock microbial mats growing in the intertidal zone of Heron Island (Great Barrier Reef, Australia) was investigated with a pulse amplitude modulation chl fluorometer providing four different excitation wave-lengths for preferential excitation of the major algal groups (cyanobacteria, green algae, diatoms/dinoflagellates). A new type of fiberoptic emitter-detector unit (PHYTO-EDF) was used to measure chl fluorescence at the sample surface. Fluorescence signals mainly originated from cyanobacteria, which could be almost selectively assessed by 640-nm excitation. Even after desiccation for long time periods under full sunlight, beachrock showed rapid recovery of photosynthesis after rehydration in the light (t1/2 ∼ 15 min). However, when rehydrated in the dark, the quantum yield of energy conversion of PSII remained zero over extended periods of time. Parallel measurements of O2 concentration with an oxygen microoptode revealed zero oxygen concentration in the surface layer of rehydrated beachrock in the dark. Upon illumination, O2 concentration increased in parallel with PSII quantum yield and decreased again to zero in the dark. It is proposed that oxygen is required for preventing complete dark reduction of the PSII acceptor pools via the NADPH-dehydrogenase/chlororespiration pathway. This hypothesis is supported by the observation that PSII quantum yield could be partially induced in the dark by flushing with molecular oxygen.
