Chrystal, J & Larkum, AWD 1988, 'Preservation of long-wavelength fluorescence in the isolated thylakoids of two phytoplanktonic algae at 77 K', BBA - Bioenergetics, vol. 932, no. C, pp. 189-194.
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Loss of long-wavelength fluorescence upon isolation of chloroplasts or thylakoids has long been a problem in studies of the chromophyte algae, that is, algae possessing chlorophyll c and related algae. We now report the preservation of long-wavelength fluorescence, using two such algae, Phaeodactylum tricornutum (Bacillariophyta) and Vischeria helvetica (Eusigmatophyta). Preservation was achieved using an isolation buffer of high osmotic and ionic strength. Anions high on the Hofmeister series were more efficient than anions low on the Hofmeister series. The most efficient buffer was one high in phosphate (0.5 M) and citrate (0.3 M) combined with 0.3 M sucrose. The results indicate that there are basic differences at the molecular level between the arrangement in the thylakoid membrane of chlorophyll-protein complexes of the chromophyte and related algae compared to green algae and higher plants. © 1988.
Hiller, RG, Larkum, AWD & Wrench, PM 1988, 'Chlorophyll proteins of the prymnesiophyte Pavlova lutherii (Droop) comb. nov.: Identification of the major light-harvesting complex', BBA - Bioenergetics, vol. 932, no. C, pp. 223-231.
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A chlorophyll ac-fucoxanthin light-harvesting protein has been separated by SDS-polyacrylamide gel electrophoresis and by digitonin-sucrose density centrifigation from thylakoids of Pavlova lutherii. It contains a single major polypeptide of 21 kDa, comprises 69% of the total chlorophyll a and is enriched in chlorophyll c compared to the thylakoids. Energy transfer from chlorophyll c and fucoxanthin to chlorophyll a was demonstrated within the protein complex. Antibodies to the 21 kDa apoprotein showed cross-reactivity with the 26-28 kDa apoproteins of higher plant light-harvesting chlorophyll a b protein and with the 19 kDa apoprotein of the light-harvesting complex of diatoms, but much reduced or no cross-reactivity with the major thylakoid polypeptides of dinoflagellates and cryptophytes. © 1988.
Larkum, AWD 1988, 'High rates of nitrogen fixation on coral skeletons after predation by the crown of thorns starfish Acanthaster planci', Marine Biology, vol. 97, no. 4, pp. 503-506.
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At One Tree Reef, Great Barrier Reef, Australia, between 1983 and 1985, corals killed by the crown of thorns seastar Acanthaster planci L. gave rise to skeletons which were colonised rapidly by blue-green and other algae. For the next 3 to 9 mo these coral skeletons showed over three times more nitrogen fixation (acetylene reduction) than control substratum rates (9 to 32 nmol vs 3 to 10 nmol C2H2 cm-2 h-1, over all seasons). These values convert to relatively high annual fixation rates of 37 to 127 kg N ha-1 yr-1 but, at the low densities of A. planci on One Tree Reef (ca. 0.65 ha-1), this has little impact on the total nitrogen fixation rate and, as a result, on the level of organic nitrogen in the system. However, it is suggested that on reefs subjected to high aggregations of a. planci such an effect would enhance the level of organic nitrogen and lead to greater primary and secondary production throughout the reef system. © 1988 Springer-Verlag.
Larkum, AWD, Kennedy, IR & Muller, WJ 1988, 'Nitrogen fixation on a coral reef', Marine Biology, vol. 98, no. 1, pp. 143-155.
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Acetylene reduction was used to assess nitrogen fixation on all major substrates at all major areas over a period of 1 to 6 yr (1980-1986) at One Tree Reef (southern Great Barrier Reef). Experiments using 15N2 gave a ratio of 3.45:1.0 for C2H2 reduced:N2 fixed. Acetylene reduction was largely light-dependent, saturated at 0.15 ml C2H2 per ml seawater, and linear over 6 h. High fixation was associated with two emergent cyanophyte associations, Calothrix crustacea and Scytonema hofmannii, of limited distribution. Subtidally, the major contribution to nitrogen fixation came from well-grazed limestone substrates with an epilithic algal community in the reef flat and patch reefs (3 to 15 nmol C2H4 cm-2 h-1). Similar substrates from the outer reef slope showed lower rates. Nitrogen fixation on beach rock, intertidal coral rubble, reef crest and lagoon sand was relatively small (0.3 to 1.0 nmol C2H4 cm-2 h-1). Seasonal changes in light-saturated rates were small, with slight reduction only in winter. Rates are also reported for experimental coral blocks (13 to 39 nmol cm-2 h-1) and for branching coral inside and outside territories of gardening damselfish (3 to 28 nmol cm-2 h-1). This work supports the hypothesis that the high nitrogen fixation on the reef flat and patch reefs of the lagoon (34 to 68 kg N ha-1 yr-1) is because these subtidal areas support highly disturbed communities with the greatest abundance of nitrogen-fixing cyanophyte algae. It is calculated from a budget of all areas that One Tree Reef has an annual nitrogen fixation rate of 8 to 16 kg N ha-1 yr-1. © 1988 Springer-Verlag.
RAVEN, JA & SAMUELSSON, G 1988, 'ECOPHYSIOLOGY OF FUCUS-VESICULOSUS L CLOSE TO ITS NORTHERN LIMIT IN THE GULF OF BOTHNIA', BOTANICA MARINA, vol. 31, no. 5, pp. 399-410.
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