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191.
Heat-acclimated rats show lighter IBAT deposit with different gross composition and lower GDP-binding than controls at thermoneutrality. A thermal disactivation of the tissue is then inferred. Cafeteria regime increased IBAT mass and GDP-binding when offered to rats at a thermoneutral ambient temperature. These results indicate that BAT thermogenesis at thermoneutrality is not the lowest one of the tissue and that diet-induced thermogenesis can take place even at thermoneutrality. 相似文献
192.
Iron mobilization in three animal models of inflammation 总被引:2,自引:0,他引:2
M T Carbonell M P Sáiz M T Martí J Queralt M T Mitjavila 《Revista Espanola de Fisiología》1989,45(2):163-170
The effect of acute, subchronic, and chronic experimental models of inflammation upon hematocrit, hemoglobin, serum iron and ferritin iron and nonheme iron concentration in the liver and spleen has been studied in the rat. In the acute model (carrageenan oedema) no iron mobilization took place, whereas in the chronic models differences in iron mobilization were observed, related to their different chronicity and to the time elapsed from induction. The carrageenan-induced granuloma (from 12 h to 8 days) (subchronic model) was accompanied by a decrease of plasma iron (12 and 24 h), a later decrease of the hematocrit values (2 and 4 days) and high ferritin and nonheme iron concentrations in the liver and spleen for 4 days, followed by a tendency to return to the control values. The anemia in the adjuvant arthritis (from 1 to 4 weeks after induction) (chronic model) was observed at 7 days and is related to increased iron stores in the liver and spleen. However, the iron store levels in liver decreased and fell later below control values. The increase of ferritin and nonheme iron concentrations may be responsible for the reduced availability of iron release from tissue. 相似文献
193.
194.
A method for sequential estimation of nuclear DNA and silver staining of nucleoli in plant cells is described. Feulgen staining is done first and nuclear DNA estimated by absorption cytophotometry. Following this, the slides are stained with AgNO3. The method has been used to study the process of nucleolar fusion in garlic (Allium sativum L.) meristem root tip cells. It was found that during interphase nucleoli rarely fused, thus most fusion must have occurred before the G1 phase of the cell cycle. 相似文献
195.
In renal sac nephrocytes of Helix aspersa, intracellular calcium has been localized using the oxalate-pyroantimonate (OPA) and phosphate-pyroantimonate (PPA) methods. Pyroantimonate precipitates are preferentially localized in the excretory spherule and in vesicles located in the basal and lateral regions of the nephrocyte. Such vesicles appear to release their content into the excretory vacuole. Calcium may interact with diverse types of molecules present in the excretory vacuole, thus favouring stabilization and packaging of the excretory spherule. 相似文献
196.
Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains 总被引:2,自引:0,他引:2
E Gomez-Lucía J Goyache J A Orden J L Blanco J A Ruiz-Santa-Quiteria L Domínguez G Suárez 《Applied and environmental microbiology》1989,55(6):1447-1451
The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity. 相似文献
197.
Summary Germination of condiospores fromA.niger in very concentrated suspension was required to inoculate solid fermentation media, but a germination self-inhibitor was detected in spores. It was found that the inhibitory effect depended on the composition of the medium and was reduced when glucose was used as a carbon source. The effect of the self-inhibitor was eliminated by washing the spores and using glucose and a protein nitrogen source in the germination medium. By this method it was possible to increase about 100 times (106 to 108) spore concentration, keeping more than 90% germination. 相似文献
198.
V Sklenár J Kypr A Bax G Zon M Vorlícková 《International journal of biological macromolecules》1989,11(5):273-277
DNA fragments d(TATATATA) and d(TATATA) were studied in low-salt aqueous solutions and found to coexist in more than one conformer. 1H-n.m.r. demonstrates that single-stranded and double-stranded states are involved in the conformational coexistence. Circular dichroism spectroscopy indicates a global B-DNA stacking of bases in the fragments. 31P-n.m.r. resonances of the TpA and ApT phosphodiester bonds are substantially separated in the spectra of both d(TATATATA) and d(TATATA) duplexes to suggest an alternating architecture of their backbones. In fact, the oligonucleotide duplexes are much more alternating than the corresponding polynucleotide under the same solution conditions. The alternating character of the d(TATATATA) double helix is further enhanced in molar caesium fluoride solutions. The oligonucleotide isomerization into X-DNA is, however, accompanied by gel formation, which makes high resolution n.m.r. measurements impossible. 相似文献
199.
In order to study the in vivo assembly of chromatin on prokaryotic DNA templates, we have transformed yeast cells with plasmids pAJ50 and pRB58, which contain pBR322 sequences. In both cases nucleosomes are assembled in vivo on pBR322 DNA, although the nucleosomes are not homogeneous in size. To explore whether there is any preference for nucleosome assembly along pBR322 sequences, we have used an indirect end labeling method. The results indicate that most nucleosomes are placed at random on pBR322, although the probability for histone octamers to interact with some short regions is somewhat reduced. These regions coincide with sequences in which the frequency distribution of nucleosomes reconstituted in vitro (E. Caffarelli et al. (1988) Eur. J. Biochem. 171, 497-501) is low. Sequence determinants that direct chromatin assembly in vitro seem thereby to act to some extent in vivo. 相似文献
200.
J A García-Sáinz S M Hernández-Sotomayor J L Contreras-Rodríguez M Macías-Silva 《Biochemistry international》1989,18(1):243-249
The stimulations of ureagenesis and cyclic AMP accumulation induced by glucagon were inhibited by 10 nM vasopressin or 100 nM phorbol 12-myristate 13-acetate (PMA). The maximal accumulation of cyclic AMP induced by glucagon was clearly diminished by these agents without change in the EC50 for the peptide hormone suggesting a non-competitive type of inhibition. H-7 blocked the inhibition of glucagon-stimulated ureagenesis induced by PMA and vasopressin and diminished their effect on the accumulation of cyclic AMP induced by glucagon. It is concluded that activation of protein kinase C inhibits the stimulation of ureagenesis and the accumulation of cyclic AMP induced by glucagon in liver cells from hypothyroid rats; H-7 inhibits the effects of protein kinase C activation. 相似文献