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Rampant horizontal transfer and duplication of rubisco genes in eubacteria and plastids 总被引:16,自引:2,他引:14
Previous work has shown that molecular phylogenies of plastids,
cyanobacteria, and proteobacteria based on the rubisco (ribulose-1,5-
bisphosphate carboxylase/oxygenase) genes rbcL and rbcS are incongruent
with molecular phylogenies based on other genes and are also incompatible
with structural and biochemical information. Although it has been much
speculated that this is the consequence of a single horizontal gene
transfer (of a proteobacterial or mitochondrial rubisco operon into
plastids of rhodophytic and chromophytic algae), neither this hypothesis
nor the alternative hypothesis of ancient gene duplication have been
examined in detail. We have conducted phylogenetic analyses of all
available bacterial rbcL sequences, and representative plastid sequences,
in order to explore these alternative hypothesis and fully examine the
complexity of rubisco gene evolution. The rbcL phylogeny reveals a
surprising number of gene relationships that are fundamentally incongruent
with organismal relationships as inferred from multiple lines of other
molecular evidence. On the order of six horizontal gene transfers are
implied by the form I (L8S8) rbcL phylogeny, two between cyanobacteria and
proteobacteria, one between proteobacteria and plastids, and three within
proteobacteria. Alternatively, a single ancient duplication of the form I
rubisco operon, followed by repeated and pervasive differential loss of one
operon or the other, would account for much of this incongruity. In all
probability, the rubisco operon has undergone multiple events of both
horizontal gene transfer and gene duplication in different lineages.
相似文献
47.
Polymorphism and divergence at the 5' flanking region of the sex- determining locus, Sry, in mice 总被引:3,自引:0,他引:3
We have investigated patterns of evolution in the nonrecombining portion of
the Y chromosome in mice by comparing levels of polymorphism within Mus
domesticus with levels of divergence between M. domesticus and M. spretus.
A 1,277-bp fragment of noncoding sequence flanking the sex determining
locus (Sry) was PCR amplified, and 1,063 bases were sequenced and compared
among 20 M. domesticus and 1 M. spretus. Two polymorphic base substitutions
and two polymorphic insertion/deletion sites were identified within M.
domesticus; nucleotide diversity was estimated to be 0.1%. Divergence
between M. domesticus and M. spretus for this region (1.9%) was slightly
lower than the average divergence of single-copy nuclear DNA for these
species. Comparison of levels of polymorphism and divergence at Sry with
levels of polymorphism and divergence in the mitochondrial DNA control
region provided no evidence of a departure from the expectations of neutral
molecular evolution. These findings are consistent with the presumed lack
of function for much of the Y chromosome.
相似文献
48.
We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment. 相似文献
49.
Richard A Stabler Lisa F Dawson Petra CF Oyston Richard W Titball Jim Wade Jason Hinds Adam A Witney Brendan W Wren 《BMC microbiology》2008,8(1):177
Background
Human and animal health is constantly under threat by emerging pathogens that have recently acquired genetic determinants that enhance their survival, transmissibility and virulence. We describe the construction and development of an Active Surveillance of Pathogens (ASP) oligonucleotide microarray, designed to 'actively survey' the genome of a given bacterial pathogen for virulence-associated genes. 相似文献50.
Crystalline aldolase 总被引:1,自引:0,他引:1