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1.
Nigel J. Fuller Dorothy M. Stirling Stephen Dunnett Gavin P. Reynolds Margaret Ashwell 《Bioscience reports》1987,7(2):121-127
The effects of reducing brain serotonin (5-HT) levels by means of intracerebral-ventricular injections of the tryptophan antagonist p-chlorophenylalanine (PCPA) were investigated in male rats. Six days after the operation, PCPA-treated rats, either fedad libitum or pair-fed to the food intake of control rats, showed decreased thermogenic activity and capacity in their interscapular brown adipose tissue (BAT) and also increased fat storage in their white adipose tissue (WAT). These results indicate that serotonergic synapses might play a regulatory role in the sympathetic control of BAT thermogenesis and in the rate of WAT deposition (by an as yet unidentified mechanism), in addition to their well established role in controlling food intake. 相似文献
2.
Expression of mRNA encoding basic fibroblast growth factor (bFGF) in bovine corpora lutea and cultured luteal cells. 总被引:2,自引:0,他引:2
A radiolabelled cRNA was synthesized using a 1.4 kb cDNA complementary to mRNA encoding bovine basic fibroblast growth factor (bFGF) as a template, and used as a probe to investigate the expression of mRNA encoding bFGF in bovine ovarian tissue, and luteal cells in primary culture. Northern analysis of poly(A +)RNA prepared from follicles and corpora lutea of various stages revealed a major mRNA species of 7 kb in corpora lutea of all stages, the amount of which was higher late in the luteal phase. No hybridizable message was detectable in follicles of any size. When luteal cells were established in primary culture, expression of the 7 kb mRNA species was maintained. This expression was increased markedly when cells were treated with LH/hCG or Bt2cAMP. Prostaglandin F-2 alpha treatment caused a marked decrease in the basal content of this 7 kb mRNA, and also severely impaired the ability of LH to stimulate this expression. 相似文献
3.
Bennetto H. P. Delaney G. M. Mason J. R. Roller S. D. Stirling J. L. Thurston C. F. 《Biotechnology letters》1985,7(10):699-704
Sucrose was used as a fuel in a thionine-mediated microbial fuel cell containingProteus vulgaris serving as the biocatalyst in the anode compartment. The measured yields show that under suitable conditions the substrate may be oxidised quantitatively to electricity and carbon dioxide. 相似文献
4.
T W Meade M V Vickers S G Thompson Y Stirling A P Haines G J Miller 《BMJ (Clinical research ed.)》1985,290(6466):428-432
The epidemiological characteristics of platelet aggregability were established in 958 participants in the Northwick Park Heart Study. The main analyses were based on the dose of adenosine diphosphate at which primary aggregation occurred at half its maximum velocity. Aggregability increased with age in both sexes, was greater in whites than blacks (particularly among men), and tended to decrease with the level of habitual alcohol consumption. Aggregability was, however, greater in women than men and in nonsmokers than smokers. There was no relation between aggregability on the one hand and obesity, current or past oral contraceptive use, menopausal state, or blood cholesterol and triglyceride concentrations on the other. Aggregability was somewhat, though not significantly, higher in men with a history of ischaemic heart disease and in those with electrocardiographic evidence of ischaemia than in those without. There was a strong association between the plasma fibrinogen concentration and aggregability. The widely held concept of platelet aggregability and its implications is probably an oversimplification. In the prevention of thrombosis it may be as useful to consider modifying external influences on platelet behaviour, such as plasma fibrinogen concentration or thrombin production, as it is to rely solely on platelet active agents. 相似文献
5.
6.
Anita B. Williams G.R. Stirling † A.C. Hayward J. Perry 《Journal of applied microbiology》1989,67(2):145-156
When they were subjected to a range of physical and chemical treatments, spores of Pasteuria penetrans showed properties similar to those of other endospore-forming bacteria. The spores did not take up some stains, were resistant to desiccation and sonication and showed extrusion of spore contents ('spore popping') on prolonged exposure to 0.1% KMnO4 in 0.3 n HNO3 . Calcium and dipicolinic acid (DPA) were present at concentrations of 0.28% and 0.96% of the spore dry weight respectively, giving a Ca: DPA molar ratio of 1.2. The infectivity of P. penetrans spores was reduced to a low level after heating at 100°C for 5 min, but spore attachment was not markedly affected by heating at 100°C for 15 min. Evidence for the presence of catalase in P. penetrans spores was equivocal because the low levels of catalase activity observed in spore suspensions may have been due to contamination from catalase-positive nematode tissue. When P. penetrans spores were exposed to a range of substances known to act as germinants for spores of Bacillus spp., germination or loss of refractility was not observed by phase microscopy. In vitro culture of P. penetrans was attempted by inoculating either spores or vegetative mycelial bodies onto a diverse range of simple and complex media and incubating them in aerobic, reduced oxygen, anaerobic and increased CO2 environments. Signs of spore germination or growth of vegetative stages were never observed. 相似文献
7.
8.
Multiple N-ethylmaleimide-sensitive components are required for endosomal vesicle fusion. 总被引:11,自引:5,他引:6
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This report examines the inhibition of endosomal vesicle fusion by the alkylating agent N-ethylmaleimide (NEM). The concentration of NEM required to inhibit vesicle fusion depended upon whether membrane and cytosolic fractions were treated separately or together, enabling the resolution of at least two components to the inhibition. The first component is inactivated at low levels of NEM when cytosolic and membrane fractions are treated together. On the contrary, inhibition of the second component required higher levels of NEM but was achieved by treating cytosol and membranes separately. Reconstitution studies indicated that both components were cytosolic and that neither corresponded to the ubiquitous NEM-sensitive fusion protein (NSF). The role of NSF in this fusion reaction was further examined using salt-washed membranes depleted of NSF protein. Under these conditions the fusion reaction was fully dependent upon added NSF whose activity, in this context, was sensitive to NEM treatment. From these data we conclude that NSF activity during endosomal vesicle fusion can be dissected into several steps, only a subset of which (perhaps attachment of NSF to the membrane) are sensitive to NEM. Fusion between salt-washed endosomal membranes was also dependent on soluble NSF attachment proteins. 相似文献
9.
The soluble methane mono-oxygenase of Methylococcus capsulatus (Bath). Its ability to oxygenate n-alkanes, n-alkenes, ethers, and alicyclic, aromatic and heterocyclic compounds. 总被引:39,自引:0,他引:39
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1. Methane mono-oxygenase of Methylococcus capsulatus (Bath) catalyses the oxidation of various substituted methane derivatives including methanol. 2. It is a very non-specific oxygenase and, in some of its catalytic properties, apparently resembles the analogous enzyme from Methylomonas methanica but differs from those found in Methylosinus trichosporium and Methylomonas albus. 3. CO is oxidized to CO2. 4. C1-C8 n-alkanes are hydroxylated, yielding mixtures of the corresponding 1- and 2-alcohols; no 3- or 4-alcohols are formed. 5. Terminal alkenes yield the corresponding 1,2-epoxides. cis- or trans-but-2-ene are each oxidized to a mixture of 2,3-epoxybutane and but-2-en-1-ol with retention of the cis or trans configuration in both products; 2-butanone is also formed from cis-but-2-ene only. 6. Dimethyl ether is oxidized. Diethyl ether undergoes sub-terminal oxidation, yielding ethanol and ethanal in equimolar amounts. 7. Methane mono-oxygenase also hydroxylates cyclic alkanes and aromatic compounds. However, styrene yields only styrene epoxide and pyridine yields only pyridine N-oxide. 8. Of those compounds tested, only NADPH can replace NADH as electron donor. 相似文献
10.
E Simpson M Lauber M Demeter D Stirling R Rodgers G Means M Mahendroo M Kilgore C Mendelson M Waterman 《The Journal of steroid biochemistry and molecular biology》1991,40(1-3):45-52
In recent years it has become apparent that tropic hormones involved in steroidogenesis act to regulate the expression of the enzymes involved in the various steroidogenic pathways. This is particularly evident in the ovary where the episodic secretion of steroids throughout the ovarian cycle is regulated largely by changes in the levels of the particular enzymes involved in each step of the steroid biosynthetic pathways. Recently, the genes for the various cytochrome P450 species involved in ovarian steroidogenesis, namely cholesterol side-chain cleavage P450 (P450SCC), 17 alpha-hydroxylase P450 (P450(17 alpha], and aromatase cytochrome P450 (P450AROM) have been isolated and characterized, making it possible to study the regulation of expression at the molecular level. To this end, a series of chimeric constructs have been prepared in which fragments of the 5'-untranslated region of bovine P450(17 alpha) and P450SCC have been inserted upstream of the chloramphenicol acetyl transferase (CAT) and beta-globin reporter genes. These constructs have been used to transfect primary cultures of bovine luteal and thecal cells. The results indicate that cAMP responsiveness lies within defined regions of genes which do not contain a classical CRE, similar to previous results utilizing adrenal cells in culture. Furthermore, although constructs containing both the P450(17 alpha) and P450SCC 5'-upstream regions are expressed in both luteal and thecal cell cultures, only those containing the P450SCC sequences are expressed in luteal cells. Studies on the expression of P450AROM indicate that the promoter which is responsible for its expression in human placenta is not operative in the corpus luteum. Thus estrogen biosynthesis may be regulated by the differential use of tissue specific promoters, thus accounting for the complexity and multifactorial nature of the expression of this activity. 相似文献