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931.
H B?ttcher J Nittinger S Engel P Fürst 《Journal of biochemical and biophysical methods》1991,23(2):181-187
A microcalorimetric method was developed to facilitate long-term assessment of energy balance in isolated fat cells. White rat adipocytes were primary cultured in glass ampoules with a matrix of agar-gel. Heat production was measured continuously over 3 days with an LKB BioActivityMonitor. In order to assist interpretation of the microcalorimetric measurements, glucose consumption and lactate and pyruvate production were determined in parallel cultures. Heat production, glucose consumption and lactate production were in an apparent steady state throughout the study whether employing aerobic (94 pW, 0.50 and 0.44 pmol/cell. h, respectively) or partial anaerobic experimental conditions (39 pW, 0.41 and 0.57 pmol/cell.h, respectively). However, oxygen availability influenced the apparent heat production and glucose and lactate metabolism. With partial anaerobiosis a 59% lower heat production, an 18% lower glucose consumption and a 30% higher lactate production than by employing aerobic experimental conditions were observed. 相似文献
932.
PACAP, a VIP-like peptide, in neurons of the esophagus. 总被引:1,自引:0,他引:1
R Uddman A Luts A Absood A Arimura M Ekelund H Desai R H?kanson G Hambreaus F Sundler 《Regulatory peptides》1991,36(3):415-422
The lower esophagus of guinea-pig, cat, sheep and man was analyzed for pituitary adenylate cyclase activating peptide (PACAP), a novel vasoactive intestinal peptide (VIP)-like peptide, using immunocytochemistry and radioimmunoassay. PACAP-immunoreactive nerve fibers were numerous in the longitudinal and circular muscle layers of sheep and man, moderate in numbers in cat, while being few in the esophagus of guinea-pig. A few PACAP-immunoreactive nerve cell bodies and numerous nerve fibers were seen in the myenteric ganglia of the esophagus of cat, sheep and man. In the lower esophagus of cat, sheep and man all PACAP-containing nerve cell bodies and nerve fibers stored VIP. The results of radioimmunoassay of PACAP in extracts of specimens from man were in good agreement with the immunocytochemical findings. High performance liquid chromatography revealed one major peak of PACAP-like immunoreactivity in extracts of human esophagus. We suggest that neuronal PACAP may serve to modulate motor activity and secretion in the lower esophageal sphincter region. 相似文献
933.
Per-Ola Arvidsson CharlotteEva Bratt Lars-Erik Andréasson Hans-Erik ?kerlund 《Plant Growth Regulation》1991,10(4):381-382
Book Review
Photosynthesis: Molecular biology and bioenergeticsG.S. Singhal, J. Barber, R.A. Dilley, Govindjee, R. Haselkorn and P. Mohanty (Eds), Proceedings of the International Workshop on Application of Molecular Biology and Bioenergetics of Photosynthesis. Berlin, Heidelberg, New York, London, Paris, Tokyo, Hong Kong and Narosa: Springer-Verlag, 1989. xiv+441 pages. DM 148,00. ISBN 3-540-50451-6 相似文献934.
Harald Sverdrup Salim Belyazid Bengt Nihlg?rd Lars Ericson 《Plant Growth Regulation》1991,10(2):173-174
Book Review
Plant protoplasts and genetic engineering IIY.P.S. Bajaj (Ed.), (Biotechnology in Agriculture and Forestry, Vol. 9). Berlin: Springer-Verlag, 1989. 510 pages. DM398.00. ISBN 3-540-50789-2 相似文献935.
Immobilized dyes have been used primarily for purification of nucleotide dependent enzymes and proteins from plasma and other sources. Due to their low costs, high protein binding capacity and resistance to degradation dyes bear the potential as ligand for affinity separation of proteins on a large scale. In this paper dyes have been used for precipitation of proteins. Using albumin, prealbumin, alpha 1-acid glycoprotein and immunoglobulin G as model proteins we could demonstrate that dye-promoted precipitation depends on several factors which include the structure of the dye, the pH of the solution, the dye/protein molar ratio and the intrinsic properties of the proteins. It revealed that most of the dyes tested were endowed with the precipitating potential. The efficacy of precipitation was found to increase with the complexity of the dye structure. However, the amount of a dye required for total precipitation was found to be different for a given protein. Electrostatic as well as hydrophobic forces are involved in the mechanism of precipitation. It was demonstrated that by optimizing the conditions, mixtures of proteins can be resolved by dye-promoted precipitation. The high sensitivity of the reaction offers the possibility of using this method for rapid concentration of very diluted protein solutions. 相似文献
936.
The accessory gland of the male Drosophila melanogaster plays a vital role in reproduction. This secretory organ synthesizes products that are transferred to the female and are necessary to elicit the proper physiological and behavioral responses in the female. The accessory gland is composed of two morphologically distinct secretory cell types, the main cells and the secondary cells. Previous studies identified some genes expressed in main cells or in all accessory gland cells. In this paper we use P-element mediated enhancer traps to examine gene expression in the accessory gland. We show that, in addition to genes expressed in main cells only or in all accessory gland secretory cells, there are genes expressed specifically in secondary cells. Each cell type is uniform in the expression of its genes. Our results demonstrate that the two cell types are not only morphologically distinct but also biochemically distinct. We also show that the two cell types differ in their regulation of gene expression in response to mating activity. 相似文献
937.
Eugene M. Rinchik Terry Magnuson Bernadette Holdener-Kenny Gavin Kelsey Albert Bianchi Claudio J. Conti Fran?ois Chartier Kathryn A. Brown Stephen D. M. Brown Josephine Peters 《Mammalian genome》1992,3(Z1):S104-S120
Chair of Committee for Mouse Chromosome 7 相似文献
938.
Parthenogenetic stem cells in postnatal mouse chimeras. 总被引:1,自引:0,他引:1
E M J?gerbauer A Fraser E W Herbst R Kothary R Fundele 《Development (Cambridge, England)》1992,116(1):95-102
The ability of parthenogenetic (pg) cells to contribute to proliferating stem cell populations of postnatal aggregation chimeras was investigated. Using DNA in situ analysis, pg participation was observed in highly regenerative epithelia of various regions of the gastrointestinal tract, e.g., stomach, duodenum and colon, in the epithelia of tongue and uterus and in the epidermis. Pg cells also contributed to the epithelium of the urinary bladder, which is characterized by a relatively slow cellular turnover. Using a sensitive proliferation marker to determine division rate of pg and normal (wt) cells in tissues of a 24-day-old chimera, no significant differences between pg and fertilized cells were observed. However, in colon and uterus of a pg <==> wt chimera aged 101 days, a significant loss of proliferative capacity of pg cells was found. In the colon, this loss of proliferative potential was accompanied by an altered morphology of pg crypts. In general, they were situated at the periphery of the epithelium and lacked access to the lumen, with consequent cystic enlargement and flattened epithelium. No obvious morphological changes were observed in the pg-derived areas of the uterine epithelium of this chimera. Our results provide evidence that pg cells can persist as proliferating stem cells in various tissues of early postnatal chimeras. They suggest that pg-derived stem cells may cease to proliferate in restricted areas of the gastrointestinal tract and in the uterine epithelium of pg <==> wt chimeras of advanced age.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
939.
An enzyme electrode was constructed for amperometric determination of xylose and glucose. The electrode is based on the PQQ-dependent membrane-bound aldose dehydrogenase (ALDH) from Gluconobacter oxydans. ALDH was covalently immobilized on a graphite electrode. Immobilized dimethylferrocene, soluble ferrocene carboxylic acid and phenazine methosulphate were used as electron transfer mediators. When xylose was measured electrochemically using an electrode modified with ALDH and dimethylferrocene, the linear measurement range extended to 100 mM. For glucose measurement the linear measurement range was about one-tenth of that for xylose. The electrode showed fairly good stability; 50% of the original electrode response was still obtained after 5 days of intermittent use. The effect of possible leakage of adsorbed mediator was determined by measuring the response of an electrode with soluble mediator as a function of time. The reproducibility of the electrode was good, the standard deviation of the electrode response in ten measurements with the same electrode being only 2.7%. 相似文献
940.
In the past year, much has been learned about structure-function correlations in the tubulin molecule, and specifically about the nature and roles of post-translational modifications and tubulin isotypes. The interactions between tubulin and its ligands--both microtubule-associated proteins and anti-mitotic drugs--are becoming clearer at the molecular level. 相似文献