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41.
Among all the mammalian pituitary hormones, luteinizing hormone (LH) was the most potent in vitro inducer of oocyte maturation in L. rohita, C. mrigala, C. catla and C. carpio. It induced significant germinal vesicle breakdown (GVBD) at concentrations of 10, 1, 0.1 and 0.01 micrograms/ml. At the highest concentration used, LH induced 77.9 +/- 5.9, 73.8 +/- 4.6, 50.3 +/- 2.8 and 40.8 +/- 1.4% GVBD in oocytes of L. rohita, C. mrigala, C. catla and C. carpio, respectively. Among other hormones, follicle stimulating hormone (FSH) induced only a marginally significant GVBD (13.2 +/- 0.8%) in the oocytes of C. carpio, but not in other three species. Thyroid stimulating hormone (TSH), growth hormone (GH) and prolactin (PRL) had no effect on GVBD. 相似文献
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A likelihood approach for comparing synonymous and nonsynonymous nucleotide substitution rates, with application to the chloroplast genome 总被引:29,自引:24,他引:5
A model of DNA sequence evolution applicable to coding regions is
presented. This represents the first evolutionary model that accounts for
dependencies among nucleotides within a codon. The model uses the codon, as
opposed to the nucleotide, as the unit of evolution, and is parameterized
in terms of synonymous and nonsynonymous nucleotide substitution rates. One
of the model's advantages over those used in methods for estimating
synonymous and nonsynonymous substitution rates is that it completely
corrects for multiple hits at a codon, rather than taking a parsimony
approach and considering only pathways of minimum change between homologous
codons. Likelihood-ratio versions of the relative-rate test are constructed
and applied to data from the complete chloroplast DNA sequences of Oryza
sativa, Nicotiana tabacum, and Marchantia polymorpha. Results of these
tests confirm previous findings that substitution rates in the chloroplast
genome are subject to both lineage-specific and locus-specific effects.
Additionally, the new tests suggest tha the rate heterogeneity is due
primarily to differences in nonsynonymous substitution rates. Simulations
help confirm previous suggestions that silent sites are saturated, leaving
no evidence of heterogeneity in synonymous substitution rates.
相似文献
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44.
Climate change poses an unprecedented threat to biodiversity worldwide. Consequently, unrecognised taxa may not receive adequate conservation attention to survive. We used molecular and morphological data to address the challenge of species delimitation within the genus Schilbe. The presence or absence of an adipose fin and distribution based on east-flowing, conceivably faster-flowing, or west-flowing, probably more slow-flowing, river systems were considered. Distinctive geographic patterns in genetic variation within southern, eastern, and western African populations were revealed. Particularly, the South African population is distinct from those of Namibia, Botswana and Nigeria. No individuals with rudimentary adipose fins were found at any locality, but specimens from three localities either had or did not have adipose fins. These mixed occurrences are suspected to be a result of human interventions, and that the presence of rudimentary adipose fins in the east African species could be an adaptive feature that serves to stabilise these fish in faster currents. In addition, the genetic divergence observed among African silver catfish from geographically isolated river systems is conceivably the result of micro-evolutionary adaptive responses to different environmental conditions. Collectively, these results distinguish S. depressirostris from S. intermedius. 相似文献
45.
Inbreeding in Tamil Nadu, South India 总被引:4,自引:0,他引:4
46.
Dennis V Pedersen Gregers R Andersen Dennis V Pedersen Lubka Roumenina Rasmus K Jensen Trine AF Gadeberg Chiara Marinozzi Capucine Picard Tania Rybkine Steffen Thiel Uffe BS Sørensen Cordula Stover Veronique Fremeaux-Bacchi Gregers R Andersen 《The EMBO journal》2017,36(8):1084-1099
Properdin (FP) is an essential positive regulator of the complement alternative pathway (AP) providing stabilization of the C3 and C5 convertases, but its oligomeric nature challenges structural analysis. We describe here a novel FP deficiency (E244K) caused by a single point mutation which results in a very low level of AP activity. Recombinant FP E244K is monomeric, fails to support bacteriolysis, and binds weakly to C3 products. We compare this to a monomeric unit excised from oligomeric FP, which is also dysfunctional in bacteriolysis but binds the AP proconvertase, C3 convertase, C3 products and partially stabilizes the convertase. The crystal structure of such a FP-convertase complex suggests that the major contact between FP and the AP convertase is mediated by a single FP thrombospondin repeat and a small region in C3b. Small angle X-ray scattering indicates that FP E244K is trapped in a compact conformation preventing its oligomerization. Our studies demonstrate an essential role of FP oligomerization in vivo while our monomers enable detailed structural insight paving the way for novel modulators of complement. 相似文献
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