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A diatom Synedra acus subsp. radians (Kotz.) Skabitsch. has been studied by transmission electron microscopy. Examination of ultrathin sections demonstrated that silica dissolution in ammonium fluoride pH 5 under mild conditions leaves the key ultrastructural elements intact. The ultrastructure and arrangement of the cell organelles was studied during ontogeny. Silicalemma-surrounded silica deposition vesicles (SDVs) with maturating daughter valves and forming girdle bands have been identified. This method of SDV visualization offers considerable advantages over the standard approach without silica dissolution. 相似文献
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The diversity of chloroplast forms, and their number and cellular location, as well as pyrenoid structure, distinguishes diatoms from other groups of heterokont algae. The fine chloroplast structure is considered to be informative for taxonomic and phylogenetic studies of diatoms. Six species of diatoms belonging to different classes have been examined with transmission electron microscopy. New data on the chloroplast structure have been obtained. Characteristics of the pyrenoid ultrastructure of diatoms belonging to various phylogenetic clades have been defined more precisely. The results specify the ultrastructure of pyrenoids for different phylogenetic clades of diatoms and contribute to the previously obtained data. 相似文献
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Yekaterina?D.?BedoshviliEmail authorView authors OrcID profile
return OK on get Ksenia?V.?Gneusheva Maria?S.?Popova Tatyana?N.?Avezova Kirill?Yu.?Arsentyev Yelena?V.?Likhoshway 《Protoplasma》2018,255(3):911-921
Diatoms stand out among other microalgae due to the high diversity of species-specific silica frustules whose components (valves and girdle bands) are formed within the cell in special organelles called silica deposition vesicles (SDVs). Research on cell structure and morphogenesis of frustule elements in diatoms of different taxonomic groups has been carried out since the 1950s but is still relevant today. Here, cytological features and valve morphogenesis in the freshwater raphid pennate diatom Encyonema ventricosum (Agardh) Grunow have been studied using light and transmission electron microscopy of cleaned frustules and ultrathin sections of cells, and scanning electron and atomic force microscopy of the frustule surface. Data have been obtained on chloroplast structure: the pyrenoid is spherical, penetrated by a lamella (a stack of two thylakoids); the girdle lamella consists of several short lamellae. The basic stages of frustule morphogenesis characteristic of raphid pennate diatoms have been traced, with the presence of cytoskeletal elements near SDVs being observed throughout this process. Degradation of the plasmalemma and silicalemma is shown to take place when the newly formed valve is released into the space between sister cells. The role of vesicular transport and exocytosis in the gliding of pennate diatoms is discussed. 相似文献
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Grachev MA Annenkov VV Likhoshway YV 《BioEssays : news and reviews in molecular, cellular and developmental biology》2008,30(4):328-337
Many pigmented heterokonts are able to synthesize elements of their cell walls (the frustules) of dense biogenic silica. These include diatom algae, which occupy a significant place in the biosphere. The siliceous frustules of diatoms have species-specific patterns of surface structures between 10 and a few hundred nanometers. The present review considers possible mechanisms of uptake of silicic acid from the aquatic environment, its transport across the plasmalemma, and intracellular transport and deposition of silica inside the specialized Silica Deposition Vesicle (SDV) where elements of the new frustule are formed. It is proposed that a complex of silicic acid with positively charged proteins silaffins and polypropylamines remains a homogeneous solution during the intracellular transport to SDV, where biogenic silica precipitates. The high density of the deposited biogenic silica may be due to removal of water from the SDV by aquaporins followed by syneresis--a process during which pore water is expelled from the network of the contracting gel. The pattern of aquaporins in the silicalemma, the membrane embracing the SDV, can determine the pattern of species-specific siliceous nanostructures. 相似文献
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Yulia R. Zakharova Darya P. Petrova Yuri P. Galachyants Maria V. Bashenkhaeva Maria I. Kurilkina Yelena V. Likhoshway 《Geomicrobiology journal》2018,35(8):635-647
Diatom sediment records of large lakes can be used to decipher the history of ancient phytoplankton. The upper layer of the sediment is an important area of remineralization of the sedimenting phytoplankton biomass. It hosts a bacterial community different from those of both the water column and deeper sediment layers. In this work, we analyzed the structure and diversity of the communities of Bacteria and Archaea in the surface sediment core containing valves of diatoms, the major producers in Lake Baikal. Pyrosequencing of the bacterial V3–V4 region of the 16 S ribosomal RNA (rRNA) and archaeal V1–V3 16 S rRNA gene regions yielded 29,168 and 36,997 reads, respectively. In total, we have identified 33 bacterial phyla; uncultured Actinobacteria were the most abundant in the upper layers, while lower sediment was dominated by Firmicutes and Alphaproteobacteria. The composition of the archaeal community changed with depth, but was generally dominated by Crenarchaeota from the classes Marine Group I and Miscellaneous Crenarchaeotic Group, as well as Euryarchaeota from the class Thermoplasmata. These dominant bacterial and archaeal taxa are presumed to participate in the destruction of buried organic matter, which eventually leads to degradation of the diatom valves. 相似文献
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Yulia R. Zakharova Yuri P. Galachyants Maria I. Kurilkina Alexander V. Likhoshvay Darya P. Petrova Sergey M. Shishlyannikov Nikolai V. Ravin Andrey V. Mardanov Alexey V. Beletsky Yelena V. Likhoshway 《PloS one》2013,8(4)
Insight into the role of bacteria in degradation of diatoms is important for understanding the factors and components of silica turnover in aquatic ecosystems. Using microscopic methods, it has been shown that the degree of diatom preservation and the numbers of diatom-associated bacteria in the surface layer of bottom sediments decrease with depth; in the near-bottom water layer, the majority of bacteria are associated with diatom cells, being located either on the cell surface or within the cell. The structure of microbial community in the near-bottom water layer has been characterized by pyrosequencing of the 16S rRNA gene, which has revealed 149 208 unique sequences. According to the results of metagenomic analysis, the community is dominated by representatives of Proteobacteria (41.9%), Actinobacteria (16%); then follow Acidobacteria (6.9%), Cyanobacteria (5%), Bacteroidetes (4.7%), Firmicutes (2.8%), Nitrospira (1.6%), and Verrucomicrobia (1%); other phylotypes account for less than 1% each. For 18.7% of the sequences, taxonomic identification has been possible only to the Bacteria domain level. Many bacteria identified to the genus level have close relatives occurring in other aquatic ecosystems and soils. The metagenome of the bacterial community from the near-bottom water layer also contains 16S rRNA gene sequences found in previously isolated bacterial strains possessing hydrolytic enzyme activity. These data show that potential degraders of diatoms occur among the vast variety of microorganisms in the near-bottom water of Lake Baikal. 相似文献
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A new subfamily LIP of the major intrinsic proteins 总被引:1,自引:0,他引:1
Kirill Vladimirovich Khabudaev Darya Petrovna Petrova Mikhail Aleksandrovich Grachev Yelena Valentinovna Likhoshway 《BMC genomics》2014,15(1)