Borowitzka, MA & Larkum, AWD 1987, 'Calcification in algae: Mechanisms and the role of metabolism', Critical Reviews in Plant Sciences, vol. 6, no. 1, pp. 1-45.
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Koop, K & Larkum, AWD 1987, 'Deposition of organic material in a coral reef lagoon, One Tree Island, Great Barrier Reef', Estuarine, Coastal and Shelf Science, vol. 25, no. 1, pp. 1-9.
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Deposition of organic material was measured at four sites on One Tree Island coral reef using fixed sediment traps. Although no reliable data were obtained for the reef crest area because of problems of resuspension, mean deposition in the backreef area amounted to some 4 g organic C m-2 day-1 whereas in the lagoon it was about 1·5 g C m-2 day-1. This amounted to mean nitrogen deposition rates of 160 and 95 mg N m-2 day-1, respectively. As primary production by turf algae, the principal producers at One Tree Island, has been estimated at about 2·3 g C m-2 day-1 for the whole reef system and the weighted mean carbon deposition is estimated at 2·2 g C m-2 day-1, it is clear that the carbon produced by plants is largely retained in the system. Nitrogen deposition, on the other hand, amounted to only about 60% of that produced by turf algae and it must be assumed that much of this leached into the water during sedimentation. Losses of nitrogen may be minimized by incorporation of dissolved nitrogen by pelagic microheterotrophs which may in turn be consumed by filter feeders before they leave the reef. © 1987.
Larkum, AWD, Cox, GC, Hiller, RG, Parry, DL & Dibbayawan, TP 1987, 'Filamentous cyanophytes containing phycourobilin and in symbiosis with sponges and an ascidian of coral reefs', Marine Biology, vol. 95, no. 1, pp. 1-13.
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A study was made of the ultrastructure and pigment composition of filamentous cyanophytes living in symbiosis with several sponges and a colonial didemnid ascidian collected from the southern end of the Great Barrier Reef, Australia, between 1983 and 1986. The sponges were Dysidea herbacea Keller and several other encrusting sponges which have not been identified; the ascidian was Trididemnum miniatum Kott (1977). The cyanophyte Oscillatoria spongeliae (Shultz) Hauck was identified as the symbiont of several of the sponges, including D. herbacea. Two other unidentified Oscillatoria species were found in a bristly papillate sponge and in T. miniatum. Chlorophyll a, alone, was present in all the symbionts with the exception of T. miniatum, which contained the cosymbiont Prochloron and where chlorophyll b was also present. Two phycoerythrins were isolated by chromatography and chromatofocusing. Both resembled C-phycoerythrin, but one of the two carried the chromophore phycourobilin as well as phycoerythrobilin possibly on both the α and β subunits, which had apparent molecular masses of 18 and 20 kdaltons. No γ subunit was present. Ultrastructurally, the three Oscillatoria species were distinguished by an unusual type of parallel, longitudinal, thylakoid organisation; the arrangement was different in detail in each species. © 1987 Springer-Verlag.
Savage, AP, Matthews, JL, Adrian, TE, Ghatei, MA, Cooke, T & Bloom, SR 1987, 'Effect of a long-acting analogue of somatostatin, SMS 201-995, on the development of intestinal tumours in azoxymethane-treated rats', Carcinogenesis, vol. 8, no. 4, pp. 561-563.
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Savage, AP, Matthews, JL, Ghatei, MA, Cooke, T & Bloom, SR 1987, 'Enteroglucagon and experimental intestinal carcinogenesis in the rat.', Gut, vol. 28, no. 1, pp. 33-39.
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To assess the association between the putative intestinal trophic hormone enteroglucagon and the development of intestinal tumours, four groups of 20 rats underwent either jejunal transection or 20%, 50%, or 80% proximal small bowel resection. Tumours were induced with azoxymethane 10 mg/kg weekly for 12 weeks. At 26 weeks there was a promotion of colonic neoplasia from a median of 0.5 (range 0-3) per rat in the transection group to 1.0 (0-3) in the 50% resected group (p less than 0.01) but no significant promotion in the 80% resection group. In the small bowel, increasing resection resulted in a progressive promotion of tumours from a median of 1.0 (range 0-3) per rat in the transection group to 2.0 (0-5) in the 50% resection group (p less than 0.001) and 3.0 (0-11) in the 80% group (p less than 0.01). Plasma enteroglucagon was measured at 2, 16, and 26 weeks and was raised seven-fold in the 80% resected group (p less than 0.001). There was a significant correlation between enteroglucagon concentrations and number of duodenal tumours but not colonic tumours. Crypt cell production rate in the duodenum increased from 11.5 +/- 1.9 to 29.2 +/- 1.4 cells/crypt/h in the 80% resected group (p less than 0.001) and showed a close correlation with both enteroglucagon levels and tumour promotion in the small bowel. There were no changes in crypt cell production rate in the colon with resection. This study shows a close association between enteroglucagon concentrations, promotion of tumours and crypt cell production rate in the duodenum but not in the colon.