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Lopez JV; Culver M; Stephens JC; Johnson WE; O'Brien SJ 《Molecular biology and evolution》1997,14(3):277-286
Differential rates of nucleotide substitution among different gene segments
and between distinct evolutionary lineages is well documented among
mitochondrial genes and is likely a consequence of locus-specific selective
constraints that delimit mutational divergence over evolutionary time. We
compared sequence variation of 18 homologous loci (15 coding genes and 3
parts of the control region) among 10 mammalian mitochondrial DNA genomes
which allowed us to describe different mitochondrial evolutionary patterns
and to produce an estimation of the relative order of gene divergence. The
relative rates of divergence of mitochondrial DNA genes in the family
Felidae were estimated by comparing their divergence from homologous
counterpart genes included in nuclear mitochondrial DNA (Numt, pronounced
"new might"), a genomic fossil that represents an ancient transfer of 7.9
kb of mitochondrial DNA to the nuclear genome of an ancestral species of
the domestic cat (Felis catus). Phylogenetic analyses of mitochondrial
(mtDNA) sequences with multiple outgroup species were conducted to date the
ancestral node common to the Numt and the cytoplasmic (Cymt) mtDNA genes
and to calibrate the rate of sequence divergence of mitochondrial genes
relative to nuclear homologous counterparts. By setting the fastest
substitution rate as strictly mutational, an empirical "selective
retardation index" is computed to quantify the sum of all constraints,
selective and otherwise, that limit sequence divergence of mitochondrial
gene sequences over time.
相似文献
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Blastomyces dermatitidis, a dimorphic fungus, can infect man and cause chronic, suppurative, and granulomatous lesions in any part of the body. AlthoughSalfelder (1965) andDiSalvo &Denton (1963) commented on differences in virulence observed between isolates of this fungus, host factors pertaining to susceptibility have not been elucidated. BecauseConant et al. (1954) reported that males contract the natural disease 9 times more often than females, the present work was undertaken to study factors pertaining to this difference in susceptibility. 相似文献
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Pires A Guilbault TR Mitten JV Skiendzielewski JA 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2000,127(1):37-47
We investigated roles of catecholamines in metamorphosis of the prosobranch gastropod, Crepidula fornicata. Levels of DOPA, norepinephrine (NE) and dopamine (DA) were measured by high-pressure liquid chromatography (HPLC) in competent larvae and juvenile siblings that metamorphosed in response to the natural adult-derived cue or to elevated K+. Competent larvae contained 1.58 +/- 0.26 (S.E.M.) x 10(-2) pmol DOPA, 0.91 +/- 0.45 x 10(-2) pmol NE, and 0.290 +/- 0.087 pmol DA (mean values per microg total protein, n = 4 batches of larvae). Levels of DA per individual were not different between larvae and juvenile siblings; levels of NE were higher in juveniles. The tyrosine hydroxylase (TH) inhibitor alpha-methyl-DL-m-tyrosine (alpha-MMT) depleted DOPA and DA to approximately half of control values without affecting levels of NE. Depletion of DOPA and DA was accompanied by inhibition of metamorphosis in response to the natural cue but not to elevated K+. The dopamine-beta-hydroxylase inhibitor diethyldithiocarbamate (DDTC) induced high frequencies of metamorphosis at concentrations of 0.1-10 microM. In juveniles induced by 10 microM DDTC, levels of both NE and DA averaged approximately 80% of those in control larvae. Catecholamines may function as endogenous regulators of metamorphosis in C. fornicata. 相似文献
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Qingwei Zhang Zhiren Xia Michael J. Mitten Loren M. Lasko Vered Klinghofer Jennifer Bouska Eric F. Johnson Thomas D. Penning Yan Luo Vincent L. Giranda Alexander R. Shoemaker Kent D. Stewart Stevan W. Djuric Anil Vasudevan 《Bioorganic & medicinal chemistry letters》2012,22(24):7615-7622
A high throughput screening (HTS) hit, 1 (Plk1 Ki = 2.2 μM) was optimized and evaluated for the enzymatic inhibition of Plk-1 kinase. Molecular modeling suggested the importance of adding a hydrophobic aromatic amine side chain in order to improve the potency by a classic kinase H-donor–acceptor binding mode. Extensive SAR studies led to the discovery of 49 (Plk1 Ki = 5 nM; EC50 = 1.05 μM), which demonstrated moderate efficacy at 100 mpk in a MiaPaCa tumor model, with no overt toxicity. 相似文献
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苏云金芽胞杆菌幕虫亚种T02菌株的伴胞晶体在芽胞外壁内侧形成,呈现晶胞粘连的现象。在此菌株中克隆了cry26 Aa和cry28 Aa两个基因,并对晶胞粘连现象与质粒的相关性做了系统研究。通过消除幕虫亚种T02菌株的质粒,得到了仅消除cry26 Aa所在质粒的菌株BMB1151和无质粒的菌株BMB1152。通过穿梭载体将cry26 Aa和cry28 Aa两个基因分别和同时转化无质粒突变株BMB1152并表达,形成的晶体与芽胞独立存在不能粘连,表明在幕虫亚种染色体背景下仅仅cry的表达不能形成晶胞粘连现象,从而推断晶胞粘连现象可能与幕虫亚种两个基因所在的质粒有关;进一步的研究发现将cry26 Aa在仅消除cry26 Aa所在质粒的突变株BMB1151中表达,形成的晶体与芽胞也分别独立存在不能粘连,从而进一步推断幕虫亚种晶胞粘连现象与cry26 Aa所在质粒有关。 相似文献