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61.
Tanya Marchant Ritgak Dimka Tilley-Gyado Tsegahun Tessema Kultar Singh Meenakshi Gautham Nasir Umar Della Berhanu Simon Cousens Joanna RM Armstrong Schellenberg 《PloS one》2015,10(5)
BackgroundFamilies in high mortality settings need regular contact with high quality services, but existing population-based measurements of contacts do not reflect quality. To address this, in 2012, we designed linked household and frontline worker surveys for Gombe State, Nigeria, Ethiopia, and Uttar Pradesh, India. Using reported frequency and content of contacts, we present a method for estimating the population level coverage of high quality contacts.ConclusionsMeasuring content of care to reflect the quality of contacts can reveal missed opportunities to deliver best possible health care. 相似文献
62.
Background
Pichia stipitis xylose reductase (Ps-XR) has been used to design Saccharomyces cerevisiae strains that are able to ferment xylose. One example is the industrial S. cerevisiae xylose-consuming strain TMB3400, which was constructed by expression of P. stipitis xylose reductase and xylitol dehydrogenase and overexpression of endogenous xylulose kinase in the industrial S. cerevisiae strain USM21. 相似文献63.
Reduced natural selection associated with low recombination in Drosophila melanogaster 总被引:8,自引:1,他引:7
Synonymous codons are not used equally in many organisms, and the extent of
codon bias varies among loci. Earlier studies have suggested that more
highly expressed loci in Drosophila melanogaster are more biased,
consistent with findings from several prokaryotes and unicellular
eukaryotes that codon bias is partly due to natural selection for
translational efficiency. We link this model of varying selection intensity
to the population-genetics prediction that the effectiveness of natural
selection is decreased under reduced recombination. In analyses of 385 D.
melanogaster loci, we find that codon bias is reduced in regions of low
recombination (i.e., near centromeres and telomeres and on the fourth
chromosome). The effect does not appear to be a linear function of
recombination rate; rather, it seems limited to regions with the very
lowest levels of recombination. The large majority of the genome apparently
experiences recombination at a sufficiently high rate for effective natural
selection against suboptimal codons. These findings support models of the
Hill-Robertson effect and genetic hitchhiking and are largely consistent
with multiple reports of low levels of DNA sequence variation in regions of
low recombination.
相似文献
64.
Kappa-chain constant-region gene sequences in genus Rattus: coding regions are diverging more rapidly than noncoding regions 总被引:2,自引:0,他引:2
We have determined the nucleotide sequence of a 1,200-base pair (bp)
genomic fragment that includes the kappa-chain constant-region gene (C
kappa) from two species of native Australian rodents, Rattus leucopus
cooktownensis and Rattus colletti. Comparison of these sequences with each
other and with other rodent C kappa genes shows three surprising features.
First, the coding regions are diverging at a rate severalfold higher than
that of the nearby noncoding regions. Second, replacement changes within
the coding region are accumulating at a rate at least as great as that of
silent changes. Third, most of the amino acid replacements are localized in
one region of the C kappa domain--namely, the carboxy-terminal "bends" in
the alpha-carbon backbone. These three features have previously been
described from comparisons of the two allelic forms of C kappa genes in R.
norvegicus. These data imply the existence of considerable evolutionary
constraints on the noncoding regions (based on as yet undetermined
functions) or powerful positive selection to diversify a portion of the
constant-region domain (whose physiological significance is not known).
These surprising features of C kappa evolution appear to be characteristic
only of closely related C kappa genes, since comparison of rodent with
human sequences shows the expected greater conservation of coding regions,
as well as a predominance of silent nucleotide substitutions within the
coding regions.
相似文献
65.
A simplified method of processing of fine needle aspirates for paraffin miniblocks suitable for both morphologic and immunocytochemical evaluation is described. Aspirates were fixed in ethanol at 4 degrees C, dehydrated in acetone and xylene and embedded in paraffin (58 degrees C). All steps were carried out in a single Eppendorf centrifuge tube; the total process took less than four hours. Deparaffinized sections were stained using the alkaline phosphatase-antialkaline phosphatase technique with monoclonal and conventional antibodies helpful in the differential cytologic diagnosis of alcohol-fixed aspiration biopsy specimens. Antibodies to keratin, vimentin, desmin, neurofilaments, glial fibrillary acidic protein, leukocyte-common antigen, synaptophysin and immunoglobulin kappa and lambda light chains reacted positively on the miniblock material. Since the paraffin miniblocks combine the histologic pattern of the tumor with the differentiation-specific information provided by immunocytochemistry, their use can improve the accuracy of tumor typing in aspirates. 相似文献
66.
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68.
Summary The frequencies of base-line and Mitomycin-C (MMC) induced sister chromatid exchanges (SCE) were surveyed in four inbred strains of mice. In contrast to the C57B1/6J, CBA/J, and A/J strains where frequencies of SCE increased linearly with increasing dose of MMC, levels of SCE were significantly lower in AKR/J mice at high MMC concentrations. At a dose of 5 mg/kg MMC, chromosomal aberrations were more frequent in bone marrow cells of AKR/J mice than in C57B1/6J mice. These observations suggest an altered response to DNA damage in the AKR mouse strain. 相似文献
69.
Bernard-Trifilo JA Kramár EA Torp R Lin CY Pineda EA Lynch G Gall CM 《Journal of neurochemistry》2005,93(4):834-849
Integrin class adhesion proteins are concentrated at adult brain synapses. Whether synaptic integrins engage kinase signaling cascades has not been determined, but is a question of importance to ideas about integrin involvement in functional synaptic plasticity. Accordingly, synaptoneurosomes from adult rat brain were used to test if matrix ligands activate integrin-associated tyrosine kinases, and if integrin signaling targets include NMDA-class glutamate neurotransmitter receptors. The integrin ligand peptide Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) induced rapid (within 5 min) and robust increases in tyrosine phosphorylation of focal adhesion kinase, proline-rich tyrosine kinase 2 and Src family kinases. Increases were similarly induced by the native ligand fibronectin, blocked with neutralizing antibodies to beta1 integrin, and not obtained with control peptides, indicating that kinase activation was integrin-mediated. Both GRGDSP and fibronectin caused rapid Src kinase-dependent increases in tyrosine phosphorylation of NMDA receptor subunits NR2A and NR2B in synaptoneurosomes and acute hippocampal slices. Tests of the physiological significance of the latter result showed that ligand treatment caused a rapid and beta1 integrin-dependent increase in NMDA receptor-mediated synaptic responses. These results provide the first evidence that, in adult brain, synaptic integrins activate local kinase cascades with potent effects on the operation of nearby neurotransmitter receptors implicated in synaptic plasticity. 相似文献
70.
Becca Asquith Angelina J Mosley Adrian Heaps Yuetsu Tanaka Graham P Taylor Angela R McLean Charles RM Bangham 《Retrovirology》2005,2(1):1-9