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101.
Electrophoretic variation characterized by the presence (ES-5B+) or absence (ES-5B–) of esterase-5B in the plasma of the house mouse has been observed. It is suggested that the expression of esterase-5B is controlled by an autosomal locus, Esr, linked to Ldr-1 on chromosome 6, in addition to the presumptive structural locus Es-5, which is located on chromosome 8. A gene order of Lyt-3-Esr-Ldr-1 was determined by two crosses.Supported by the Deutsche Forschungsgemeinschaft (SFB 46).This is communication No. 33 of a research program devoted to the investigation of cellular distribution and genetics of nonspecific esterases. 相似文献
102.
Oocyte nuclei of the dipteran insect Heteropeza pygmaea display swift pulsating movements during in vitro follicle formation in the ovaries. Low doses of cytochalasin B (CB) completely inhibit the nuclear movements within a few minutes and cause the nuclei to assume spherical shapes. If the drug is removed, nuclear pulsation is resumed within 5–10 min. Phalloidin and colchicine do not affect the nuclear movements. Actin is shown by indirect immunofluorescence microscopy to be present in considerable amounts all over the cytoplasm of the oocytes. It is concluded that microfilaments are responsible for pulsation of the oocyte nuclei, whereas microtubules are not involved. 相似文献
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Anke Burmester Anke Wöstemeyer Jose Arnau Johannes Wöstemeyer 《Molecular & general genetics : MGG》1992,235(2-3):166-172
Summary A series of new vectors for the model zygomycete Absidia glauca was constructed on the basis of the structural neomycin resistance (Neor) gene controlled by the promoter of the gene for elongation factor 1 (TEF). In order to select for transformed colonies with a stable Neor phenotype, spores from primary transformants were pooled and grown for two sporulation cycles under non-selective conditions. Southern blot analysis of DNA from single spore isolates originating from independent transformant pools allowed the identification of two autonomously replicating plasmids. Retransformation of Escherichia coli and restriction analysis of the two plasmids provided evidence for spontaneous in vivo insertion of a new DNA element (SEG1) from the A. glauca genome. The inserted regions in both plasmids are essentially identical and do not represent repetitive DNA. Compared with other autonomously replicating vectors, these SEG1-containing plasmids are mitotically extremely stable and are passed on to the vegetative spore progeny of a retransformed A. glauca strain. We assume that SEG1 contains structural elements involved in partitioning and stable segregation of plasmids. For the construction of stable transformants of A. glauca, the SEG1 element may be regarded as a major breakthrough, because stabilization of transformed genetic traits by integration is difficult to achieve in all mucoraceous fungi and all known replicating plasmids are mitotically unstable. 相似文献
105.
PalZ - Hyperostotic fish bones from the presumable Pliocene phosphate-bearing deposits along Lake Manyara, Tanzania, are described. In contrast to marine occurrences of this kind, the pathological... 相似文献
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107.
Detection of Plasmid Transfer from Pseudomonas fluorescens to Indigenous Bacteria in Soil by Using Bacteriophage φR2f for Donor Counterselection 下载免费PDF全文
Eric Smit Jan D. van Elsas Johannes A. van Veen Willem M. de Vos 《Applied microbiology》1991,57(12):3482-3488
The transfer of a genetically marked derivative of plasmid RP4, RP4p, from Pseudomonas fluorescens to members of the indigenous microflora of the wheat rhizosphere was studied by using a bacteriophage that specifically lyses the donor strain and a specific eukaryotic marker on the plasmid. Transfer of RP4p to the wheat rhizosphere microflora was observed, and the number of transconjugants detected was approximately 103 transconjugants per g of soil when 107 donor cells per g of soil were added; transfer in the corresponding bulk soil was slightly above the limit of detection. All of the indigenous transconjugants which we analyzed contained a 60-kb plasmid and were able to transfer this plasmid to a Nxr RprP. fluorescens recipient strain. The indigenous transconjugants were identified as belonging to Pseudomonas spp., Enterobacter spp., Comamonas spp., and Alcaligenes spp. 相似文献
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McQueen Donald J. Johannes Mark R. S. Lafontaine Nathalie R. Young Andrew S. Longbotham Eric Lean David R. S. 《Hydrobiologia》1990,(1):337-341
We used two analyses to test the hypothesis that planktivore abundances contribute to the residual variations of Secchi depth
or chlorophyll-a plotted with respect to mean summer epilimnetic total phosphorus. The first analysis involved 15 lake years of data from
six lakes. The data set comprised mark-recapture assessments of piscivore and planktivore numbers and estimates of mean summer
chlorophyll-a, total phosphorus and Secchi depth. We found that residual chlorophyll-a variation was not significantly (p>0.05) correlated with planktivore densities, but that planktivore densities did contribute (p<0.02) to the residual variation of Secchi depth on mean total phosphorus. The second analysis included all of the data used
in the first plus an additional 13 lake years of data from the literature. These data showed that the percentage of the total
fish community comprising planktivores did not significantly (p>0.05) contribute to the residual variation in chlorophyll-a with respect to mean summer total phosphorus. Together, our results suggest that planktivore abundance has a significant
cascading impact on water clarity, but no long term statistically significant impact on mean summer chlorophyll-a concentration. 相似文献
110.
Dr. med. Peter W. Vaupel Johannes Otte Rolf Manz 《Radiation and environmental biophysics》1982,20(4):289-300
Summary The oxyhemoglobin saturation (HbO2) of single red blood cells within tumor microvessels (diameter: 3–12 µm) of DS-Carcinosarcoma was studied using a cryophotometric micromethod. In untreated control tumors (mean tissue temperature approx. 35° C) the measured values scattered over the whole saturation range from zero to 100 sat.%, the mean being 51 sat.%. Upon heating at 40° C for 30 min, the oxygenation of the tumor tissue significantly improved as compared with control conditions. After 40° C-hyperthermia a mean oxyhemoglobin saturation of 66 sat.% was obtained. In contradistinction to this, after 43° C-hyperthermia the tumor oxygenation was significantly lower and reached a mean HbO2 saturation value of 47 sat.%. A further temperature rise to 45° C caused the oxygenation to drop drastically (mean oxyhemoglobin saturation value: 24 sat.%). This is due to a severe restriction of nutritive blood flow.The changes in tumor oxygenation after hyperthermia seem to be predominantly mediated through changes in tumor blood flow, including tumor microcirculation, which showed a similar temperature dependence. Metabolic effects probably play a minor role in the oxyhemoglobin saturation distribution within tumor microvessels.Supported by the Deutsche Forschungsgemeinschaft (Va 57/2-1). Presented in part at the International Symposium on Biomedical Thermology, June 30 to July 4, 1981, Strasbourg, France 相似文献