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901.
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Summary The radiosensitivity of hemopoietic stem cells isolated from infant mice (6 or 9 days of life), of infant preirradiated mice (exposed to 126 rad on day 6 and assayed at day 9 of life) and of adult C57/B1 mice was assayed on the basis of their capacity to form spleen colonies and to incorporate iododeoxyuridine after transplantation into heavily irradiated hosts. Stem cells of infant non-irradiated mice have a D0 of 115 rad compared to 72 rad for adult mice whereas the D0 of preirradiated infant mice has diminished to 80 rad. No significant difference in D0 was seen between spleen and bone marrow cells or between total cells and cells not sensitive to3H-thymidine. It is postulated that this sensitization of stem cells caused by a preirradiation is responsible for the greater mortality of infant mice after fractionated exposure compared to a single one. 相似文献
904.
J Kaplan S Gerber D Bonneau J M Rozet O Delrieu M L Briard H Dollfus I Ghazi J L Dufier J Frézal 《Genomics》1992,14(4):979-987
Usher syndrome (US) is an autosomal recessive disease characterized by congenital hearing impairment and retinitis pigmentosa. It is the most frequent cause of deaf-blindness in adults and accounts for 3 to 6% of deaf children. Here, we report the genetic mapping of a gene for US type I (USH1A), the most severe form of the disease, to the long arm of chromosome 14, by linkage to probe MLJ14 at the D14S13 locus in 10 families of Western France ancestry (Z = 4.13 at theta = 0). Among them, 8 families originated from a small area of the Poitou-Charentes region (Z = 3.78 at theta = 0), suggesting that a founder effect could be involved. However, since not all US type I families were found to be linked to this locus, the present study provides evidence for genetic heterogeneity of this condition (heterogeneity versus homogeneity test HOMOG, P < 0.05; heterogeneity versus no linkage, P < 0.01). 相似文献
905.
Peter Price Steven Ostrove Christos Flordellis Mary Ann Sells Swan Thung Michael Gerber Judith Christman George ACS 《Bioscience reports》1983,3(11):1017-1026
A line of mouse cells expressing hepatitis B virus (HBV) surface and ‘e’ antigens identical in their physico-chemical properties to antigens from patients infected with HBV was isolated after transfection of 3T3 ceils with cloned HBV DNA. The studies reported here indicate that the ceils contain uninterrupted copies of the entire HBV genome which are unmethylated on CCGG sites and have no gross deletions or rearrangements. The entire core region is transcribed into polyadenylated RNAs large enough to serve as messengers for production of viral core antigen (HBcAg) yet no HBcAg can be detected. This suggests that the ceils produce a primary translation product copied from the HBcAg messenger which either cannot assume the proper configuration for display of HBcAg determinants or is rapidly converted to HBeAg by proteolysis. 相似文献
906.
Impact of Inactivated Extracellular Proteases on the Modified Flagellin Type III Secretion Pathway of Bacillus halodurans 下载免费PDF全文
Eldie Berger Erika du Plessis Isak Gerber Michael Crampton Nolwandle Nxumalo Maureen Louw 《Applied microbiology》2009,75(1):271-274
The flagellin type III secretion pathway of Bacillus halodurans BhFC01 (Δhag) was modified by the inactivation of fliD. An in-frame flagellin gene fusion polypeptide construct was expressed, and the heterologous peptides were secreted as flagellin fusion monomers. The stability of the secreted monomers was significantly enhanced through gene-targeted inactivation of extracellular proteases. 相似文献
907.
IB RODE PEDERSEN 《Nature: New biology》1971,234(47):112-114
IT has been proposed that lymphocytic choriomeningitis (LCM) virus and immunologically related viruses should be placed in a new taxonomic group, with LCM virus as the prototype virus1,2. They were called arenoviruses because they contain, as a unique feature, electron-dense, sand-like or ribo-some-like granules2. The LCM virus contains RNA and we have previously reported that this RNA can be separated into three components by density gradient centrifugation3. 相似文献
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909.
An image analysis system was used to calculate the surface area and volume of the submerged leaves of seven species of Myriophyllum. We separated the species into two categories based on their distribution and habitat differences and compared their surface area, volume, dry mass, specific leaf area, and surface to volume ratios. The geographic location and habitat of the species explained the greatest percentage of total variance for these variables when compared by analysis of variance. A leaf shape analysis was performed by regressing surface area with volume for each species. Interspecific comparisons of leaf shape were made using analysis of covariance. Fundamental interspecific differences in submerged leaf shape, associated with differences in their geographic distributions and habitats, are explained as adaptations for different nutrient uptake regimes. 相似文献
910.