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171.
G H Greeley Y S Guo G Gomez F Lluis P Singh J C Thompson 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1988,189(3):325-328
The purpose of this study was to determine whether the inhibitory action of peptide YY (PYY) on gastric acid secretion is attributable to the release of gastric somatostatin in rats. Two groups of rats (six rats/group) were anesthetized with urethane and prepared with gastric fistulas and jugular catheters. Pentagastrin (18 micrograms/kg-h) was given intravenously for 150 min to stimulate gastric acid secretion. Intravenous PYY (130 micrograms/kg-h) inhibited pentagastrin-stimulated gastric acid secretion significantly (P less than 0.05). Administration of iv PYY resulted in a 41% reduction (P less than 0.05) in pentagastrin-stimulated gastric acid secretion. In another group of anesthetized rats, administration of PYY (10(-7), 10(-8) M) failed to stimulate a release of somatostatin from the isolated-perfused rat stomach. Our findings indicate that PYY can inhibit gastric acid secretion independently of release of gastric somatostatin in the rat. 相似文献
172.
High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
相似文献
173.
Low genic variation in male-reproductive-tract proteins of Drosophila melanogaster and D. simulans 总被引:3,自引:0,他引:3
We report results, using two-dimensional gel electrophoresis (2DE), of natural population surveys of allelic variation in approximately 300 male-reproductive-tract polypeptides in both Drosophila melanogaster and its sibling species, D. simulans. Despite our efforts to maximize operational sensitivity of our 2DE gels to polymorphism, variation estimates in both species were low (proportion of polymorphic loci [P] = 9%, and average heterozygosity [H] = 1%-3%), compared with those by one-dimensional gel electrophoresis (1DE) (P = 29%-55%; H = 8%-19%) in the same populations. However, H of polymorphic loci was very similar for 2DE and 1DE proteins; and for 17 of a total of 54 polymorphic proteins, 2DE detected three or four distinct alleles. The results suggest that the differing levels of variability widely seen with 1DE and 2DE are real and reflect differing intensities of functional constraint between different classes of structural loci. However, the alternative possibility remains that 2DE has a greater between-locus unevenness of variant detection sensitivity than does 1DE. 相似文献
174.
U C Garg N Rai Y Singh G S Dhaunsi G S Sidhu N K Ganguly R Bhatnagar 《BioTechniques》1988,6(4):294-296
The activity of calmodulin as an activator of cAMP phosphodiesterase was assayed. AMP was hydrolyzed by 5'-nucleotidase, and the adenosine formed was measured by both liquid scintillation counting and spectrophotometry at 265 nm. Calmodulin activities measured by the two methods were equivalent, indicating that spectrophotometric assay of calmodulin can be used in place of the isotopic method. 相似文献
175.
Effect of mutations at Met-88 and Met-90 on the biotination of Lys-89 of the apo 1.3S subunit of transcarboxylase 总被引:3,自引:0,他引:3
The apo 1.3S subunit of transcarboxylase contains the sequence Ala-87-Met-88-Lys-89-Met-90, and it is Lys-89 that is biotinated. This sequence is highly conserved in all the biotin enzymes that have been sequenced (with the exception of acetyl-CoA carboxylase from chicken liver, which has Val in place of Ala). The role of Met-88 and Met-90 in specifying Lys-89 for biotination by synthetase was examined by site-directed mutagenesis. Genes of the 1.3S subunit coding for Thr-88, Leu-88, or Leu-90 were generated by oligonucleotide-directed in vitro mutagenesis and expressed in Escherichia coli. The mutated apo 1.3S subunits were isolated and the biotination by homogeneous synthetase from Propionibacterium shermanii was compared with that of the apo wild-type subunit. The Vmax for the apo mutants was the same as that for the apo wild type, but when Leu was substituted for Met-88 or Met-90, the Km for the mutant was lower than that of the wild-type or mutant Thr-88. The activity of the synthetase of E. coli was determined by an in vivo assay. During the early log phase of growth, a smaller portion of mutants Thr-88 and Leu-90 was biotinated than with the wild-type or mutant Leu-88. When the cultures progressed to stationary phase, mutants and the wild type were biotinated to the same extent. The overall results show that Met-88 and Met-90 are not required for biotination of the apo 1.3S subunit by the synthetases. 相似文献
176.
Influence of the food plants ofHeliothis armigera (Hb.) on the degree of parasitism by exotic parasiteCotesia kazak Telenga (Hymenoptera: Braconidae) was studied in cages in the laboratory on 7 food plants such as cotton (Gossypium hirsutum L.), tomato (Lycopersicon esculentum Mill), okra [Abelmoschus esculentus (L.) Moench], Dolichos (dolichos lablab L.), pigeonpea [Cajanus cajan (L.) Millsp.], Cowpea (Vigna unquiculata (L.) and chickpea (Cicer arietium L.). To determine the preference of the parasite 2 test methods were employed. In single plant choice test cotton was most
preferred. Next in order of preference were tomato and okra. Dolichos, pigeonpea, cowpea and chickpea were least preferred.
In multiple choice test, however, cotton and okra were preferred followed by tomato. Parasites were seen visiting these plants
very frequently and high parasitism was recorded on these plants. Chick pea, pigeon pea, cowpea and Dolichos were the least
preferred food plants. There appears to be some difference in fecundity as affected by some food plants. Exposure on okra,
cotton and tomato resulted in higher cocoon production as compared to pigeonpea, Dolichos, cowpea and chickpea. There was,
however, no difference in sex-ratio and longevity of the progeny as affected by food plants. This exotic parasite should be
released first in crops such as cotton, okra and tomato on whichH. armigera is a very serious pest in India and elsewhere.
Contribution No. 140/86 of the Indian institute of Horticultural Research, Bangalore-560 089 相似文献
177.
A A Pollice J P McCoy S E Shackney C A Smith J Agarwal D R Burholt L E Janocko F J Hornicek S G Singh R J Hartsock 《Cytometry》1992,13(4):432-444
A cell fixation and permeabilization procedure consisting of sequential paraformaldehyde and methanol was evaluated and found suitable for concomitant flow cytometric quantification of total cellular DNA, immunofluorescence measurements of cell surface proteins, and immunofluorescence measurements of intracellular proteins. Paraformaldehyde/methanol-fixed cells exhibited significantly greater intracellular antitubulin immunofluorescence than cells fixed with paraformaldehyde or methanol alone (p less than 0.002) and significantly greater intracellular antitubulin immunofluorescence than cells fixed with methanol followed by paraformaldehyde (p less than 0.006). With paraformaldehyde/methanol fixation, cell morphology was well preserved and forward and right angle light scatter properties were sufficiently well maintained to permit gating on these parameters. Cell surface marker staining with fluorescent anti-leukocyte antibodies was unaffected by fixation with paraformaldehyde/methanol. Paraformaldehyde effects on the intensity of DNA staining with propidium iodide were dependent on paraformaldehyde concentration and fixation temperature; these effects were least pronounced at low paraformaldehyde concentrations (0.25% or less), and at temperatures lower than 37 degrees C. Paraformaldehyde fixation may result in differences in propidium iodide staining of DNA in some diploid cells, which may produce small spurious aneuploid peaks in normal peripheral blood leukocytes. Paraformaldehyde fixation also produces an apparent increase in the DNA index of aneuploid cell populations in comparison with methanol fixation, particularly when the DNA index exceeds 1.5. Occasionally, this paraformaldehyde fixation-induced effect is useful in identifying biologically distinct near-diploid subpopulations in tumors. 相似文献
178.
The possibility of interaction of hepatocytes with the heparin binding domain of Fibronectin was examined. Rat hepatocytes
adhered to coverslips coated with the 33-kDa heparin binding fragment of the C-terminal region of plasma fibronectin. When
different concentrations of the heparin binding fragment were used to coat coverslips and used as substratum, cell attachment
showed saturation kinetics. Half the maximum attachment was observed at 30–40 min after seeding of cells. The cells became
flat after 2–3 h indicating that they spread on the heparin binding domain as they do on intact fibronectin. Among the different
glycosaminoglycans tested, maximum inhibition of attachment was observed for heparin. However it was not possible to completely
inhibit attachment even at high concentrations. These results indicate that hepatocytes interact with fibronectin not only
through the Arg-Gly-Asp-containing cell binding fragment, but also through the heparin binding domain of fibronectin and,
further, that there exist heparin-dependent and heparin-independent mechanisms of interaction of cells with the 33-kDa heparin
binding fragment of fibronectin 相似文献
179.
The efficacies of four different concentrations (3, 5, 8 and 10 mg/ml) of an aqueous extract of the Andrographis peniculata were tested on growth and aflatoxin production by Aspergillus flavus in liquid SMKY medium. The maximum inhibition of aflatoxin production and growth of A. flavus were marked at 10 mg/ml (i.e. 78.6% aft. B1 and 75.1% growth). Growth and aflatoxin production were co-related processes. 相似文献
180.
Arvind Kumar Bhatt Tek Chand Bhalla Hari Om Agrawal N. Sharma 《Letters in applied microbiology》1992,15(1):1-4
An extracellular chitosanase produced by Rhodotorula gracilis CFR-1 that catalyses a limited degradation of chitosan with no detectable generation of glucosamine or reducing groups was identified. Ultracentrifugation, polyacrylamide gel electrophoresis and gel permeation studies suggest that chitosan of average molecular mass 36000 Da was reduced by the enzymic catalysis to nearly one-fourth this size without further hydrolysis of the products. The enzyme, produced constitutively by this yeast, was partially purified and some of its properties were studied. 相似文献