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Positive selection is a general phenomenon in the evolution of abalone sperm lysin 总被引:36,自引:21,他引:15
Lysin is a 16kDa acrosomal protein used by abalone sperm to create a hole
in the egg vitelline envelope (VE). The interaction of lysin with the VE is
species-selective and is one step in the multistep fertilization process
that restricts heterospecific (cross-species) fertilization. For this
reason, the evolution of lysin could play a role in establishing prezygotic
reproductive isolation between species. Previously, we sequenced sperm
lysin cDNAs from seven California abalone species and showed that positive
Darwinian selection promotes their divergence. In this paper an additional
13 lysin sequences are presented representing species from Japan, Taiwan,
Australia, New Zealand, South Africa, and Europe. The total of 20 sequences
represents the most extensive analysis of a fertilization protein to date.
The phylogenetic analysis divides the sequences into two major clades, one
composed of species from the northern Pacific (California and Japan) and
the other composed of species from other parts of the world. Analysis of
nucleotide substitution demonstrates that positive selection is a general
process in the evolution of this fertilization protein. Analysis of
nucleotide and codon usage bias shows that neither parameter can account
for the robust data supporting positive selection. The selection pressure
responsible for the positive selection on lysin remains unknown.
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2.
Vanlandschoot P Roobrouck A Van Houtte F Leroux-Roels G 《Biochemical and biophysical research communications》2002,297(3):486-491
Yeast expressed Hepatitis B surface antigen (rHBsAg) binds to monocytes through interaction with the LPS binding protein (LBP) and the LPS receptor CD14. Charged phospholipids of rHBsAg determine the interaction with these proteins. Although attachment of rHBsAg resembles the pro-inflammatory binding of LPS to CD14, rHBsAg does not activate monocytes and even reduces the expression of pro-inflammatory cytokines by LPS-stimulated monocytes. It is reported here that addition of rHBsAg to LPS-stimulated PBMC often results in increased secretion of IL-10, suggesting a similarity between the interaction of monocytes with apoptotic cells and rHBsAg. Using THP-1 cells, it is shown that IL-10 is not necessary to reduce TNFalpha protein levels. Addition of rHBsAg to LPS-stimulated cells reduces TNFalpha mRNA levels, but does not affect phosphorylation of p65 NF-kappaB and p38 MAP kinase. Instead, a reduced phosphorylation of ERK-1/2 and JNK-1/2 MAP kinases is observed. 相似文献
3.
Mitochondrial DNA and bindin gene sequence evolution among allopatric species of the sea urchin genus Arbacia 总被引:3,自引:1,他引:2
Sea urchins of the genus Arbacia (order Stirodonta) have discontinuous
allopatric distributions ranging over thousands of kilometers.
Mitochondrial DNA (mtDNA) sequences were used to reconstruct phylogenetic
relationships of four Arbacia species and their geographic populations.
There is little evidence of genetic structuring of populations within
species, except in two cases at range extremes. The mtDNA sequence
differentiation between species suggests that divergence occurred about 4-9
MYA. Gene sequences encoding the sperm protein bindin and its intron were
obtained and compared with the mtDNA phylogeny. Sea urchins among the
well-studied echinoid order Camarodonta, with degrees of mtDNA divergence
similar to those of Arbacia species, are known to have remarkable variation
in bindin. However, in Arbacia, little variation in deduced amino acid
sequences of bindin was found, indicating that purifying selection acts on
the protein. In contrast, bindin intron sequences showed much
differentiation, including numerous insertion/deletions. Fertilization
experiments performed between a divergent pair of Arbacia species from the
Atlantic and Pacific Oceans revealed no evidence of blocks to gamete
recognition. In Arbacia, fertilization specificities may have evolved
relatively slowly as a result of extensive gene flow within species,
greater functional constraint on the bindin polypeptide, or reduced
selective pressure for species recognition in singly occurring species.
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4.
Females of the sea urchin Strongylocentrotus purpuratus differ in the structures of their egg jelly sulfated fucans 总被引:1,自引:0,他引:1
The egg jelly coats of sea urchins contain sulfated fucans which bind to a
sperm surface receptor glycoprotein to initiate the signal transduction
events resulting in the sperm acrosome reaction. The acrosome reaction is
an ion channel regulated exocytosis which is an obligatory event for sperm
binding to, and fusion with, the egg. Approximately 90% of individual
females of the sea urchin Strongylocentrotus purpuratus spawned eggs having
only one of two possible sulfated fucan electrophoretic isotypes, a slow
migrating (sulfated fucan I), or a fast migrating (sulfated fucan II)
isotype. The remaining 10% of females spawned eggs having both sulfated
fucan isotypes. The two sulfated fucan isotypes were purified from egg
jelly coats and their structures determined by NMR spectroscopy and
methylation analysis. Both sulfated fucans are linear polysaccharides
composed of 1-->3-linked alpha-L-fucopyranosyl units. Sulfated fucan I
is entirely sulfated at the O -2 position but with a heterogeneous
sulfation pattern at O -4 position. Sulfated fucan II is composed of a
regular repeating sequence of 3 residues, as follows: [3-alpha-L-Fuc p -
2,4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-
1]n. Both purified sulfated fucans have approximately equal potency in
inducing the sperm acrosome reaction. The significance of two structurally
different sulfated fucans in the egg jelly coat of this species could
relate to the finding that the sperm receptor protein which binds sulfated
fucan contains two carbohydrate recognition modules of the C-type lectin
variety which differ by 50% in their primary structure.
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S Mora-Lee MS Sirerol-Piquer M Gutiérrez-Pérez U Gomez-Pinedo VD Roobrouck T López M Casado-Nieto G Abizanda MT Rabena C Verfaille F Prósper JM García-Verdugo 《PloS one》2012,7(8):e43683
Stroke represents an attractive target for stem cell therapy. Although different types of cells have been employed in animal models, a direct comparison between cell sources has not been performed. The aim of our study was to assess the effect of human multipotent adult progenitor cells (hMAPCs) and human mesenchymal stem cells (hMSCs) on endogenous neurogenesis, angiogenesis and inflammation following stroke. BALB/Ca-RAG 2(-/-) γC(-/-) mice subjected to FeCl(3) thrombosis mediated stroke were intracranially injected with 2×10(5) hMAPCs or hMSCs 2 days after stroke and followed for up to 28 days. We could not detect long-term engraftment of either cell population. However, in comparison with PBS-treated animals, hMSC and hMAPC grafted animals demonstrated significantly decreased loss of brain tissue. This was associated with increased angiogenesis, diminished inflammation and a glial-scar inhibitory effect. Moreover, enhanced proliferation of cells in the subventricular zone (SVZ) and survival of newly generated neuroblasts was observed. Interestingly, these neuroprotective effects were more pronounced in the group of animals treated with hMAPCs in comparison with hMSCs. Our results establish cell therapy with hMAPCs and hMSCs as a promising strategy for the treatment of stroke. 相似文献
7.
S. Devillard J. Aubineau F. Berger Y. Lonard A. Roobrouck S. Marchandeau 《Mammalian Biology》2008,73(2):128-137
Despite their pest status in numerous areas throughout the World, the populations of European rabbits (Oryctolagus cuniculus) have strongly decreased in South Western Europe since the mid-20th century. Such a decrease constitutes a major threat on top predators and calls for a better understanding of its mechanisms to provide suitable management responses. Infectious diseases have been invoked as the main responsible factors, but they cannot by themselves explain the magnitude of this decrease. Habitat fragmentation may indeed act as a synergetic factor, and habitat use studies are needed to better understand the impact of fragmentation on rabbit population dynamics. We investigated the variability of home range size with respects to age, sex and season in three wild populations of rabbits using telemetry. Home ranges were smaller in the highest density populations (7333 and 6878 vs. 20,492 m2) suggesting differences in habitat quality between the populations. In addition, home range sizes were larger during the reproductive season for both sexes, and adults tended to have smaller home ranges than juveniles. Clearly, the home range sizes reported here were smaller than those previously reported in rabbits. 相似文献
8.
Because of their ability to self-renew and differentiate, adult stem cells are the in vivo source for replacing cells lost on a daily basis in high turnover tissues during the life of an organism. Adult stem cells however, do suffer the effects of aging resulting in decreased ability to self-renew and properly differentiate. Aging is a complex process and identification of the mechanisms underlying the aging of (stem) cell population(s) requires that relatively homogenous and well characterized populations can be isolated. Evaluation of the effect of aging on one such adult stem cell population, namely the hematopoietic stem cell (HSC), which can be purified to near homogeneity, has demonstrate that they do suffer cell intrinsic age associated changes. The cells that support HSC, namely marrow stromal cells, or mesenchymal stem cells (MSC), may similarly be affected by aging, although the inability to purify these cells to homogeneity precludes definitive assessment. As HSC and MSC are being used in cell-based therapies clinically, improved insight in the effect of aging on these two stem cell populations will probably impact the selection of sources for these stem cells. 相似文献
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