Publications

HOWE, CJ, BEANLAND, TJ, LARKUM, AWD & LOCKHART, PJ 1992, 'PLASTID ORIGINS', TRENDS IN ECOLOGY & EVOLUTION, vol. 7, no. 11, pp. 378-383.
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Kuhl, M & Jorgensen, BB 1992, 'Microsensor measurements of sulfate reduction and sulfide oxidation in compact microbial communities of aerobic biofilms', Applied and Environmental Microbiology, vol. 58, no. 4, pp. 1164-1174.
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The microzonation of O2 respiration, H2S oxidation, and SO42- reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100 µm) with microsensors for O2, S2-, and pH. Specific reaction rates were calculated from measured concentration profiles by using a simple one-dimensional diffusion reaction model. The importance of electron acceptor and electron donor availability for the microzonation of respiratory processes and their reaction rates was investigated. Oxygen respiration was found in the upper 0.2 to 0.4 mm of the biofilm, whereas sulfate reduction occurred in deeper, anoxic parts of the biofilm. Sulfate reduction accounted for up to 50% of the total mineralization of organic carbon in the biofilms. All H2S produced from sulfate reduction was reoxidized by O2 in a narrow reaction zone, and no H2S escaped to the overlying water.

Kuhl, M & Jorgensen, BB 1992, 'Spectral light measurements in microbenthic phototrophic communities with a fiber-optic microprobe coupled to a sensitive diode array detector', Limnology and Oceanography, vol. 37, no. 8, pp. 1813-1823.

Lockhart, PJ, Beanlandi, TJ, Howe, CJ & Larkum, AWD 1992, 'Sequence of Prochloron didemni atpBE and the inference of chloroplast origins', Proceedings of the National Academy of Sciences of the United States of America, vol. 89, no. 7, pp. 2742-2746.
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The prochlorophytes, oxygenic photosynthetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green plants and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron didemni, we have cloned and sequenced its atpBE genes. Phylogenetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed.

Lockhart, PJ, Howe, CJ, Bryant, DA, Beanland, TJ & Larkum, AWD 1992, 'Substitutional bias confounds inference of cyanelle origins from sequence data', Journal of Molecular Evolution, vol. 34, no. 2, pp. 153-162.
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Available molecular and biochemical data offer conflicting evidence for the origin of the cyanelle of Cyanophora paradoxa. We show that the similarity of cyanelle and green chloroplast sequences is probably a result of these two lineages independently developing the same pattern of directional nucleotide change (substitutional bias). This finding suggests caution should be exercised in the interpretation of nucleotide sequence analyses that appear to favor the view of a common endosymbiont for the cyanelle and chlorophyll- b-containing chloroplasts. The data and approaches needed to resolve the issue of cyanelle origins are discussed. Our findings also have general implications for phylogenetic inference under conditions where the base compositions (compositional bias) of the sequences analyzed differ. © 1992, Springer-Verlag New York Inc. All rights reserved.

Lockhart, PJ, Penny, D, Hendy, MD, Howe, CJ, Beanland, TJ & Larkum, AWD 1992, 'Controversy on chloroplast origins', FEBS Letters, vol. 301, no. 2, pp. 127-131.
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Controversy exists over the origins of photosynthetic organelles in that contradictory trees arise from different sequence, biochemical and ultrastructural data sets. We propose a testable hypothesis which explains this inconsistency as a result of the differing GC contents of sequences. We report that current methods of tree reconstruction tend to group sequences with similar GC contents irrespective of whether the similar GC content is due to common ancestry or is independently acquired, Nuclear encoded sequences (high GC) give different trees from chloroplast encoded sequences (low GC). We find that current data is consistent with the hypothesis of multiple origins for photosynthesis organelles and single origins for each type of light harvesting complex. © 1992.

Murray, DR & Larkum, AWD 1992, 'Nitrogen content of seeds of Zostera capricorni and Zostera marina', Aquatic Botany, vol. 43, no. 1, pp. 87-91.
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The nitrogen (N) content of mature seeds of Zostera capricorni Aschers, was found by Kjeldahl analysis to be 1.70% of dry matter. The larger seeds of Zostera marina L. were analysed individually by the more sensitive Heraeus procedure. The mean seed N content of these seeds was 1.37% of dry matter (range 1.20-1.56%, standard deviation (SD) 0.13). Seed water contents were similar for both species, 34.7% and 32.3% of seed mass, respectively. The ecological, physiological and evolutionary significance of these observations is discussed. © 1992.

O'Meara, TJ, Nesa, M, Raadsma, HW, Saville, DG & Sandeman, RM 1992, 'Variation in skin inflammatory responses between sheep bred for resistance or susceptibility to fleece rot and blowfly strike', Research in Veterinary Science, vol. 52, no. 2, pp. 205-210.
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Ralph, PJ, Burchett, M & Pulkownik, A 1992, 'Distribution Of Extractable Carbohydrate Reserves Within The Rhizome Of The Seagrass Posidonia-Australis Hook F', Aquatic Botany, vol. 42, no. 4, pp. 385-392.
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Rhizomes of Posidonia australis Hook. f., collected from Botany Bay on the eastern coast of Australia, were analysed for extractable carbohydrates. The concentration of extractable carbohydrate in the stelar tissue of the rhizome was significantly higher

Sandeman, RM, Chandler, RA, Collins, BJ & O'Meara, TJ 1992, 'Hypersensitivity responses and repeated infections with Lucilia cuprina, the sheep blowfly', International Journal for Parasitology, vol. 22, no. 8, pp. 1175-1177.
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Seaton, DS, O'meara, TJ, Chandler, RA & Sandeman, RM 1992, 'The sheep antibody response to repeated infection with Lucilia cuprina', International Journal for Parasitology, vol. 22, no. 8, pp. 1169-1174.
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Ajani, PA 1992, 'Hunter Environmental Monitoring Program (Oral Presentation). Australian Marine Science Association Annual Conference 1992, Western Australia.', Hunter Environmental Monitoring Program. P. A.
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Oral Presentation

Mann, PA & Ajani, P 1992, 'Bioaccumulation of organochlorines and trace metals in fish—Sydney Deepwater Outfalls Environmental Monitoring Program', Proceedings of a bioaccumulation workshop: assessment of the distribution, impacts and bioaccumulation of contaminants in aquatic environments., Water Board and Australian Marine Sciences Association Inc., Sydney.

Mann, R & Ajani, PA 1992, 'Contaminants in Fish - Sydney Deepwater Ocean Outfalls (Invited Oral Presentation), Maritime Services Board 1992 Sydney Australia.', Contaminants in Fish - Sydney Deepwater Ocean Outfalls.
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Invited Oral Presentation