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VISHWANATH PATIL JON BRÅTE KAMRAN SHALCHIAN-TABRIZI KJETILL S. JAKOBSEN 《The Journal of eukaryotic microbiology》2009,56(4):394-396
ABSTRACT. Two new classes Synchromophyceae and Picophagea, belonging to the heterokonts, have been proposed recently in separate studies of 18S rRNA phylogenies. Here we revise the 18S phylogeny of these classes by including all available sequenced species and applying Bayesian and maximum likelihood methods; Synchroma grande groups with the photophagotrophic Chlamydomyxa labyrinthuloides with high statistical support. This clade is sister to Chrysophyceae, together they share a common ancestry. Our results show that the creation of class Synchromophyceae by Horn et al. was premature, because they did not include data from the closely related C. labyrinthuloides and Picophagus flagellatus species. A revision of these classes should include additional species and most likely multigene phylogenies. 相似文献
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REED ROBERT H.; COLLINS JULIAN C.; RUSSELL GEORGE 《Journal of experimental botany》1981,32(2):347-367
Ion contents and concentrations (K+, Na+, Cl, Ca2+, Mg2+,SO24, NO3, HPOJ24, amino and organic acids)of P. purpurea have been studied in relation to salinity variation.Cells were shown to accumulate large amounts of K+ and Clagainst their respective gradients of electrochemical potentialin all dilute and concentrated seawater media. Active influxof SOJ24, NO3, and HPOJ24 is also suggested,while Na+ is actively excluded from cells under hyposaline andhypersaline conditions. The relative proportions of individualcomponents of the internal osmotic potential were found to changeaccording to the external salt concentration. KCL forms themajor fraction of j} in concentrated seawater media while K+-aminoacids form the major fraction in dilute seawaters. Other intracellularsolutes comprise less than 15% oftj, in all media. Unidirectional fluxes of K+ and Cl were studied by radioisotopicmeans. Fluxes of K+ and Cl are reduced in hyposalinemedia, as is absolute KCL content per cell. Intracelhilar KCLcontent was also found to be markedly dependent upon externalK+ concentration, rather than water potential. Changes in KC1levels induced by salinity variation occur over a 6 h period. 相似文献
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