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Thylakoid membranes and Photosystem I (PS I) complexes were isolated from a glaucocystophyte, Cyanophora paradoxa, which is thought to have the most primitive ‘plastids’, and the proteins related to PS I were examined. The intrinsic light-harvesting
chlorophyll protein complexes of PS I (LHC I) were not detected by an immunological method. The PS I complexes consisted of
at least eight low-molecular-mass proteins in addition to PS I reaction center proteins. The N-terminal sequence of the PsaD
protein has higher homology to that of Chlamydomonas reinhardtii and land plants, than to that of other algae or cyanobacteria. On the other hand, the PsaL sequence has the highest homology
to those of cyanobacteria. Taking into account the other sequences of PS I components whose genes are encoded in the cyanelle
genome, and the fact that LHC I is not detected, it is concluded that PS I of C. paradoxa has chimeric characteristics of both ‘green’ lineages and cyanobacteria.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Jeffrey D. Leblond Hermina Ilea Timofte Shannon A. Roche Nicole M. Porter 《Phycological Research》2010,58(3):222-229
Glaucocystophytes are freshwater algae that possess an almost‐intact cyanobacterium, referred to as a cyanelle, as their photosynthetic organelle. Because the cyanelle represents an intermediate state in plastid evolution, glaucocystophytes have been the subject of several studies to characterize the genetics and biochemistry of their cyanelles. However, only a small handful of older studies exist on the composition of their lipids, particularly two major plastid lipids, mono‐ and digalactosyldiacylglycerol (MGDG and DGDG, respectively), found in all photosynthetic life. Our study has used a modern mass spectrometry approach, namely positive‐ion electrospray ionization/mass spectrometry/mass spectrometry, to provide a fresh interpretation of the MGDG and DGDG composition of the species, Cyanophora paradoxa Korshikov and Glaucocystis nostochinearum Itzigsohn, representing two glaucocystophyte genera. We have found that the major forms of MGDG and DGDG (with sn‐1/sn‐2 regiochemistry) are 20:5/16:0 MGDG, 20:5/20:5 MGDG, 20:5/16:0 DGDG, and 20:5/20:5 DGDG. A comparison of these four forms, along with other more minor forms of MGDG and DGDG, to two examples of cyanobacteria has revealed that glaucocystophytes do not share intact forms of MGDG and DGDG with extant cyanobacteria, but may have maintained certain C16 and C18 cyanobacterial fatty acids. 相似文献
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Jeffrey D. Leblond Hermina Ilea Timofte Shannon A. Roche Nicole M. Porter 《Phycological Research》2011,59(2):129-134
Glaucocystophytes are a group of evolutionarily important freshwater algae that have an almost intact cyanobacterium, referred to as a cyanelle, as the photosynthetic organelle. Because of this, they have been the subject of a large number of studies over the past few decades on how a cyanobacterium transitioned into a chloroplast. However, studies on their lipid composition have lagged behind those on other areas of glaucocystophyte cell biology. To this end, we have examined the sterol composition of Cyanophora paradoxa Korshikov and Glaucocystis nostochinearum Itzigsohn in order to identify sterols left unidentified in previous studies. We have found that two isolates of G. nostochinearum and one of C. paradoxa uniformly produced three sterols: 24‐methylcholest‐5‐en‐3β‐ol, 24‐ethylcholesta‐5,22E‐dien‐3β‐ol, and 24‐ethylcholest‐5‐en‐3β‐ol. 相似文献
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