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61.
Ejaculated, bovine sperm have been subjected to multiple partition in aqueous two-phase systems. This partition, carried out in a countercurrent fashion, reveals heterogeneity of the sperm population with respect to surface properties. The sperm, when partitioned in phase systems that detect non-change associated surface properties (change-insensitive) are largely distributed as two distinct populations. In charge-sensitive phase systems (which principally detect cell surface molecules carrying charge) the sperm do not show any obvious surface heterogeneity. Considerable heterogeneity is revealed in affinity-ligand phase systems containing palmitic acid coupled to one of the phase components-poly(ethylene glycol). There is a difference in surface heterogeneity between sperm which have been washed in buffer or left unwashed, direct from the ejaculate. This is indicative of weak adsorption of proteins to the sperm surface in seminal fluid. These results show that bovine ejaculated sperm is a heterogeneous cell population having unequal distributions of a number of different surface molecules. 相似文献
62.
63.
Elizabeth A. Colburn 《Hydrobiologia》1988,158(1):215-226
Salinity is a major factor influencing the distributions and abundances of aquatic macroinvertebrates of saline waters in Death Valley, California, USA. A general pattern of declining numbers of species with increasing salinity is seen in Death Valley waters. Some species are restricted to low salinities, others are found only in highly saline pools, and still others are widely distributed over a broad range of salinities.Salinity alone cannot explain distributions seen in the field. Distributions and abundances of species such as the caddisfly Limnephilus assimilis Banks are broader than would be predicted on the basis of laboratory studies of salinity and temperature. I present evidence that for such species, biotic factors such as reduced predation at high salinities may compensate for increased physiological stress. 相似文献
64.
Elizabeth R. Fielding David B. Archer Everly Conway de Macario Alberto J. L. Macario 《Applied microbiology》1988,54(3):835-836
Methanogenic bacteria were isolated from landfill sites in the United Kingdom. Strains of Methanobacterium formicicum, Methanosarcina barkeri, several different immunotypes of Methanobacterium bryantii, and a coccoid methanogen distinct from the reference immunotypes were identified. 相似文献
65.
Genetic Analysis of a Mouse t Complex Locus That Is Homologous to a Kidney Cdna Clone 总被引:3,自引:2,他引:1
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A mouse kidney cDNA clone, pMK174, identifies restriction fragment length polymorphisms (RFLPs) that map to two unlinked loci. One, designated D17Rp17, has been mapped near quaking, (qk), on chromosome 17 using three sets of recombinant inbred (RI) strains. A study of several t haplotypes resulted in the identification of t-specific alleles of D17Rp17 that map to the proximal half of the t complex. Neither t-specific nor wild-type D17Rp17 alleles are present in chromosomes carrying either the T Orleans (TtOrl) or the T hairpin tail (Thp) deletions. Comparison with other molecular markers indicates that pMK174 identifies a new proximal t complex locus, Rp17. The second locus identified by pMK174, termed D4Rp18, is tentatively assigned to chromosome 4 by mouse-Chinese hamster somatic cell hybrid analysis. 相似文献
66.
Inhibitory Effect of Autoclaving Whey-Based Medium on Propionic Acid Production by Propionibacterium shermanii 总被引:3,自引:1,他引:2
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Thomas M. Anderson Elizabeth A. Bodie Nelson Goodman Robert D. Schwartz 《Applied microbiology》1986,51(2):427-428
Propionic acid production by Propionibacterium shermanii was compared in pasteurized and autoclaved whey-based media. Propionic acid production decreased with increasing whey concentration in autoclaved media but not in pasteurized media. Increasing the yeast extract concentration from 5 to 10 g/liter greatly reduced the inhibitory effect of autoclaving. 相似文献
67.
Acclimation of a sandy soil to an air-natural gas mixture stimulated the biological oxidation of chloroform to carbon dioxide. Acetylene and methane inhibited chloroform oxidation. Chloroform oxidation continued up to 31 days in the absence of methane. Chloroform oxidation rates increased at chloroform concentrations up to 5 μg g of soil-1. 相似文献
68.
Irrespective of their age, leaves of Ginkgo biloba metabolised applied 8 (14C) zeatin to compounds of similar chromatographic properties. Glucosylation is apparently not a normal feature of cytokinin metabolism in immature leaves. However, the application of zeatin to these leaves did result in the formation of metabolites which co-chromatographed with glucosylated cytokinins. As far as cytokinin metabolism is concerned therefore, this application of excess zeatin allowed immature leaves to behave as mature or senescing leaves. Overall metabolism was fastest in immature leaves. From the metabolites formed it would appear as if oxidation, which resulted in the formation of a metabolite which co-eluted with N-(purin-6-yl)glycine, was also important in immature leaves. In senescing leaves glucosylation was the major form of metabolism. Extraction and re-application of the polar metabolites (formed from zeatin) to mature leaves resulted in the formation of compounds which co-chromatographed with zeatin. This suggests that these compounds could serve as precursors for zeatin or could be hydrolysed to form zeatin.Very little of the applied radioactivity was exported from the leaves irrespective of their physiological age. When the metabolites, obtained after zeatin application to mature leaves, were extracted and reapplied to the leaves, export of radioactive material was much improved. The results suggest that should cytokinins such as zeatin be translocated to mature leaves of this deciduous gymnosperm their export from the leaves would be unlikely unless first metabolised. In all probability the metabolites concerned are cytokinin glucosides.The financial support of the C.S.I.R., Pretoria, is gratefully acknowledged. 相似文献
69.
Dilip M. Shah Cathy M. Hironaka Roger C. Wiegand Elizabeth I. Harding Gwen G. Krivi David C. Tiemeier 《Plant molecular biology》1986,6(4):203-211
Summary We have used the cDNA clone encoding maize glutathione-S-transferase (GST I) to isolate a genomic DNA clone containing the complete GST I gene. Nucleotide sequence analysis of the cDNA and genomic clones has yielded a complete amino acid sequence for maize GST I and provided the exon-intron map of its gene. The mRNA homologous sequences in the maize GST I gene consist of a 107 bp 5 untranslated region, a 642 bp coding region and 340 bp of the 3 untranslated region. They are divided into three exons by two introns which interrupt the coding region. The 5 untranslated spacer contains an unusual sequence of pentamer AGAGG repeated seven times. The inbred maize line (Missouri 17) contains a single gene for GST I, whereas the hybrid line (3780A) contains two genes. Nucleotide sequence analysis of the primer extended cDNA products reveals that the 5 untranslated regions of the two genes in the hybrid 3780A are identical except for a 6 bp internal deletion (or insertion). The amino acid sequence of maize GST I shares no apparent sequence homology with the published sequences of animal GST's and represents the first published sequence of a plant GST. re]19850813 ac]19851126 相似文献
70.