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We have used fatty acid analyses to study the community structure of a layered endoevaporitic microbial community within a
gypsum crust that covers the bottom of a saltern evaporation pond in Eilat, Israel. This community, living at a salinity of
218–238 g l−1 total dissolved salts, consists of an upper brown layer dominated by unicellular cyanobacteria, a green layer with filamentous
cyanobacteria, a red-purple layer with both Chromatium and Ectothiorhodospira/Halorhodospira type of purple sulfur bacteria, and a black layer in which dissimilatory sulfate reduction occurs. An olive-green layer is
sometimes present below the red-purple layer. Analysis by gas chromatography/mass spectrometry of the fatty acid methyl esters
prepared from the different fractions showed characteristic patterns in each layer, and these could be related to fatty acid
composition data from the literature and to fatty acid analyses of representative halophilic microorganisms isolated from
the site. The nature of the fatty acids in the green layer suggests that the cyanobacteria present there use the oxygen-independent
pathway for production of unsaturated fatty acids, a pathway only occasionally encountered in filamentous cyanobacteria. The
facultative anaerobic nature of the cyanobacteria in the green layer was confirmed by their ability to perform anoxygenic
photosynthesis with sulfide as electron donor. Specific signature fatty acids identified for each layer corresponded well
with the microscopic and functional analysis of the biota present.
Guest Editor: John M. Melack
Saline Waters and their Biota 相似文献
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Selective stabilization by the bacteriophage 434 repressor of the plasmid expressing bovine growth hormone in Escherichia coli. 下载免费PDF全文
The maintenance of a plasmid vector-host system that selects for bacteria carrying the plasmid without the need for antibiotics is described. In this system, the bacteriophage 434 repressor gene cloned on the plasmid protects the host from lysis by a lambda imm434 cI- prophage. Cells that occasionally lose the plasmid are killed by prophage induction and therefore do not accumulate in the growing culture. The presence of the phage 434 repressor in the cells does not interfere with the process of lambda repressor inactivation and the high-level production of bovine growth hormone. 相似文献
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Noga Kronfeld-Schor Davide Dominoni Horacio de la Iglesia Oren Levy Erik D. Herzog Tamar Dayan Charlotte Helfrich-Forster 《Proceedings. Biological sciences / The Royal Society》2013,280(1765)
Most studies in chronobiology focus on solar cycles (daily and annual). Moonlight and the lunar cycle received considerably less attention by chronobiologists. An exception are rhythms in intertidal species. Terrestrial ecologists long ago acknowledged the effects of moonlight on predation success, and consequently on predation risk, foraging behaviour and habitat use, while marine biologists have focused more on the behaviour and mainly on reproduction synchronization with relation to the Moon phase. Lately, several studies in different animal taxa addressed the role of moonlight in determining activity and studied the underlying mechanisms. In this paper, we review the ecological and behavioural evidence showing the effect of moonlight on activity, discuss the adaptive value of these changes, and describe possible mechanisms underlying this effect. We will also refer to other sources of night-time light (‘light pollution’) and highlight open questions that demand further studies. 相似文献
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