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101.
102.
Sans résuméI. Analyse électrocapillaire des matières colorantes. Rev. gén. Mat. Col. 1926 Vol. 30 pp 34–45II. Phénomènes électrocapillaires et le problème du cancer. Arch. Med. Exper. 1926 Vol. I p 381III. Phénomènes électrocapillaires et l'antagonismes microbiens. Bol. Istituto Sier. Milano 1927 Vol. VI p 313. 相似文献
103.
In the companion paper (Holmquist et al. 1988), we concluded that there is
no agreement on either the correct branching order or differential rates of
evolution among the higher primates, and we examined in depth why this
uncertainty in the evolutionary understanding of our closest living
relatives persists. Recently, Lake developed two novel methods, based on
group properties of transition and transversion operators, that (a) permit,
in principle, objective resolution of problems of the above type and (b)
attach a statistical significance level to the conclusions drawn. In the
present paper, we develop formulas for using these two methods in tandem
and apply them to study transversion differences in (1) nuclear DNA for a
7-kb segment of the psi eta-globin locus and a 3-kb intergenic region
between the psi beta- and delta- globin loci and (2) mitochondrial DNA for
the 896-bp fragment of Brown et al. Although each of these nucleotide
sequence regions has its characteristic tempo and mode of evolution, the
nuclear and mitochondrial data together, comprising a total of 10,939 base
positions, support a Homo/Pan clade at the 97% confidence level. If we
calibrate the divergence point for humans and chimpanzees at 5 Myr,
consideration of the transversion branch lengths for the combined nuclear
data indicates that the gorilla lineage branched off 600,000- 900,000 years
prior to that, although the 2 sigma sampling errors do not preclude either
a temporal trifurcation for the three species or a considerably more
ancient branch point for the gorilla. To resolve the length of this central
branch to a relative accuracy of 25% and 30% will require a factor of 16
and nine times more data, respectively-- i.e., in excess of 100,000
homologous nucleotides for each of the four primates. For the nuclear
genes, heterogeneity in evolutionary rates between different parts of the
genome is mostly restricted to the human lineage for these two segments.
The lineage leading to chimpanzees has evolved 0.4 (3-kb fragment) to 3.5
(7-kb segment) times as rapidly as the lineage leading to humans, and that
leading to the gorilla has evolved approximately one-fifth to one-half as
rapidly as that leading to chimpanzees. Thus, even local molecular clocks
can "tick" badly. As significant is the fact that virtually contiguous
parts of the genome tick at markedly different rates.(ABSTRACT TRUNCATED AT
400 WORDS)
相似文献
104.
Cooperative effects between two acyclovir resistance loci in herpes simplex virus. 总被引:5,自引:3,他引:2
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The acyclovir-resistant mutant SC16 R9C2 (H.J. Field, G. Darby, and P. Wildy , J. Gen. Virol. 49:115-124, 1980) has been shown to contain two resistance loci which segregate independently on recombination with wild-type virus. One locus is in thymidine kinase, and the other is in DNA polymerase. Both induced enzymes have altered properties, thymidine kinase showing a low affinity for acyclovir and low activity, and DNA polymerase showing a low affinity for acyclovir triphosphate. Other properties of both enzymes are described which distinguish them from their wild-type counterparts. Recombinants containing either mutant thymidine kinase ( RSC -11) or mutant DNA polymerase ( RSC -26), but not both, have been used to investigate the relative contribution of each lesion to resistance and pathogenicity. Although SC16 R9C2 and both recombinants grow as well as does wild-type virus in tissue culture, they are considerably attenuated in vivo, the greatest attenuation of virulence being seen with SC16 R9C2 and RSC -26. With respect to both acyclovir resistance and in vivo growth, the lesions appear to behave synergistically. Cross resistance studies have shown the recombinant RSC -26, which contains mutant DNA polymerase but which evidently expresses wild-type thymidine kinase, to be cross resistant to both 5-iodo-2'-deoxyuridine and 5-trifluoromethyl-2'-deoxyuridine but not to (E)-5-(2-bromovinyl)-2'-deoxyuridine or 9-beta-D-arabinofuranosyladenine. 相似文献
105.
106.
Glomerular capillary basement membrane thickness (BMT) was measured in 23 rats which had had streptozocin-induced diabetes for 14 months and in 12 age-matched controls. Diabetic rats were randomly allocated to different groups, either receiving no treatment or treated with a low carbohydrate diet or insulin, or both. Control rats were randomly allocated to a normal or low carbohydrate diet. Among the diabetic rats mean plasma glucose concentrations for the groups ranged from 27-4 mmol/l (494 mg/100 ml) in the untreated rats to 9-8 mmol/l (177 mg/100 ml) in those receiving both a low carbohydrate diet and insulin. A highly significant positive relation was found between BMT and plasma glucose concentration for individual rats. When BMT was corrected for body weight a similar relation was observed. 相似文献
107.
Endopeptidases and prohormone processing 总被引:4,自引:0,他引:4
Peptide hormones and peptide transmitters are generated from polypeptide precursors by specific cleavage reactions which take place principally at sites formed by single or paired basic residues. Not all the possible cleavage sites are utilised, however, and the degree of processing of many propeptides has been found to vary according to the tissue of origin. The restricted nature of processing reactions could point to the existence of a series of enzymes with stringent specificities, recognising regions of structure in addition to the single or paired basic residues. Alternatively the action of processing enzymes may be directed by conformation of the pro-peptide which could focus the action of a protease onto or away from a particular site. In addition certain post-translational modifications such as glycosylation or phosphorylation may influence the accessibility of a site to the approach of a processing enzyme. In this review we describe recent advances that have been made in the characteristisation of proteolytic processing enzymes, we examine the relevance of the various factors that could account for restricted processing and discuss new approaches that may lead to better understanding of the mechanisms involved. 相似文献
108.
Hepatic microsomal kinetic constants and plasma half-lives and plasma clearances for the metabolism of tolbutamine were measured in the same patients. No significant correlations were found for the seven experiments performed. There was a trend to an inverse correlation between hepatic microsomal cytochrome P-450 content and the plasma clearance. The negative findings suggest a lack of variation in the hepatic drug-metabolizing activities of normal humans. 相似文献
109.
110.
Annemarie MM Vlaar Marinus JPG van Kroonenburgh Alfons GH Kessels Wim EJ Weber 《BMC neurology》2007,7(1):27