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1.
C. L. Keith R. L. Bridges L. R. Fina K. L. Iverson J. A. Cloran 《Archives of microbiology》1978,118(2):169-172
Anaerobic rupture of the benzoic acid ring was investigated. Carbon 4 was converted primarily to carbon dioxide. Following ring rupture during methane fermentation, propanoic acid is an intermediate, and carbon 4 of benzoate becomes its carboxyl.Contribution No. 1285-j, Division of Biology, Kansas State University, Manhattan, KS 66506. This work was supported in part by funds from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506. Paper II of this series is Fina and Fiskin (1960) 相似文献
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Reaction of DNA with K2PdCl4 at pH 2.0 followed by a piperidine workup produces specific cleavage at adenine (A) residues. Product analysis revealed the K2PdCl4 reaction involves selective depurination at adenine, affording an excision reaction analogous to the other chemical DNA sequencing reactions. Adenine residues methylated at the exocyclic amine (N6) react with lower efficiency than unmethylated adenine in an identical sequence. This simple protocol specific for A may be a useful addition to current chemical sequencing reactions. 相似文献
5.
Suppression and contrasuppression in the induction of contact sensitivity by the administration of cellbound antigen-antibody complexes 总被引:1,自引:0,他引:1
W Ptak M Bereta M Ptak G M Iverson D R Green 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(4):2312-2318
The tolerogenic signal produced by the i.v. injection of haptenated peritoneal exudate cells can be converted to an immunogenic signal by treating the cells with antibody to the hapten before administration. We examined this phenomenon and found that immunity induced by antigen-antibody complexes, as opposed to skin sensitization, is resistant to suppressor T cell influences. This resistance to suppression is due to the activation of an I-J+, Ly-1 T cell population which adheres to the Vicia villosa lectin, all characteristics of contrasuppressor T cells. Because haptenated cells can induce immunity if injected subcutaneously or into cyclophosphamide-pretreated recipients (thereby avoiding the induction of suppressor cells), we suggest that the activation of contrasuppressor cells by antigen-antibody complexes overrides suppressive influences in the host, allowing immunity to become dominant. The possible roles of suppression and contrasuppression in channeling the effector arm of the immune response (e.g., contact sensitivity vs humoral immunity) are discussed. 相似文献
6.
The phylogeny of the hominoid primates: a statistical analysis of the DNA-DNA hybridization data 总被引:1,自引:0,他引:1
Sibley and Ahlquist compared the single-copy nuclear DNA sequences of the
hominoid primates using DNA-DNA hybridization. From this data set they
estimated a phylogeny that clusters man and chimpanzees using a distance
Wagner procedure. However, no assessment of statistical confidence in this
estimated phylogeny was made, despite the fact that their data set contains
internal inconsistencies concerning the correct branching order. This paper
presents a modification of Pielou's Q- statistic that allows one to make
nonparametric tests of phylogenetic relationship from distance data. The
results of this analysis indicate that the estimated phylogeny of Sibley
and Ahlquist is without statistical significance owing to the internal
inconsistencies of the data set. A survey and additional analyses of other
types of molecular data indicate that the phylogeny that clusters
chimpanzees and gorillas and has the human lineage splitting off earlier is
statistically consistent with all the molecular data (including the DNA-DNA
hybridization data), whereas the phylogeny estimated by Sibley and Ahlquist
can be rejected at the 5% level using the data on restriction- endonuclease
sites in the mitochondrial genome.
相似文献
7.
The pattern of genetic differentiation among experimental populations of the flour beetle Tribolium castaneum suggested the hypothesis that relative fitness of three genotypes at the PGM-1 locus (or other linked loci) depends directly on diet. This hypothesis was tested by measuring several fitness components (developmental time, survival, fecundity, rate of egg cannibalism) on groups of individuals differing at the PGM-1 locus that were reared on three types of flour (wheat, corn and a mixture of wheat, corn, barley and rye). Flour type had large effects on all traits except larval survival to 3 weeks of age. Relative fitnesses of the three genotypes differed significantly for fecundity. Diet was found to significantly influence the relative developmental times of the three genotypes. 相似文献
8.
A method for the detection of starch hydrolysis by bacteria 总被引:2,自引:0,他引:2
9.
Dr AR Holmes RD Cannon HF Jenkinson 《Journal of industrial microbiology & biotechnology》1995,15(3):208-213
The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed. 相似文献
10.
S. J. Iverson O. T. Oftedal W. D. Bowen D. J. Boness J. Sampugna 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(1):1-12
Unlike most mammals, hooded seal (Cystophora cristata) pups are born with a substantial layer of adipose tissue. Subsequently, during the brief lactation period of only 4 days,
fasting mothers mobilize enormous amounts of lipid from blubber and secrete milk (60% fat) at rates of 10 kg·day-1. Pups gain 7 kg·day-1 due primarily to the deposition of fat in blubber. We measured blubber content and fatty acid composition of blubber and
milk in hooded seal mother-pup pairs at birth and over the 4-day lactation period to examine the nature and source of fetal
lipids, the incorporation of maternal blubber fatty acids into milk lipid, and patterns of fatty acid deposition in suckling
young. The fatty acid composition of the blubber of the newborn was notably different from that of its mother. Fetal deposition
was likely due to a combination of both fetal synthesis and direct placental transfer of maternal circulating fatty acids.
The blubber of the newborn was characterized by high levels (>90% of total fatty acids) of saturated and monounsaturated fatty
acids of primarily endogenous origin. In particular, the fetus appeared to have high Δ-9 desaturase activity as evidenced
by the large amounts of 14:1n-5 (4.2%) and 16:1n-7 (37.0%) in newborn blubber compared to maternal blubber (0.2% and 14.1%,
respectively). Nevertheless, essential and long-chain polyunsaturated fatty acids of the n-3 and n-6 families, which could
only have originated by direct transfer from the mother, comprised>7% of pup blubber fatty acids and indicated greater rates
of placental transfer than found in humans. In hooded seal mothers, rapid lipid transfer during the brief lactation period
appeared to be facilitated by direct incorporation of mobilized fatty acids into milk. Although some differences in proportions
of specific fatty acids were found between milk and maternal blubber, most of these differences declined over the course of
lactation. However, selective mobilization of 20:5n-3 from maternal blubber into milk was apparent throughout lactation and
resulted in elevated levels in pup blubber at weaning compared to maternal blubber. Ingested fatty acids were deposited directly
and without modification into the blubber of pups, and by 4 days the fatty acid composition of pup blubber was virtually identical
to that of the milk consumed. 相似文献