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71.
Matthijs G.P. Feenstra Hans Rollema Theo B.A. Mulder Ben H.C. Westerink Alan S. Horn 《Life sciences》1983,32(12):1313-1323
Evidence is presented that a low dose of peripherally administered N, N-dipropylamino-5, 6-dihydroxytetralin (DiPr-5, 6-ADTN) specifically labels dopamine (DA) receptors in rat brain.Concentrations of this potent DA receptor agonist were determined by a highly selective method using reversed phase liquid chromatography and amperometric detection. The binding characteristics satisfy all criteria regarding saturability, stereospecificity, regional distribution and relation with pharmacological effects that are associated with DA receptor interactions. A rough estimation of the density of binding sites in the striatum resulted in values of 60–70 pmol/g. Lesioning the nigrostriatal pathway does not significantly alter the amount of ligand bound, nor do pretreatments with serotonergic, α-adrenergic or β-adrenergic antagonists. DiPr-5, 6-ADTN has thus been shown to be a useful ligand for labeling central DA receptors and a powerful tool in the study of DA-ergic mechanisms. 相似文献
72.
Toxicity to Chicks of Aspergillus and Penicillium Species Isolated from Moldy Pecans 总被引:3,自引:3,他引:0
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Isolates of Aspergillus chevalieri, A. flavus, A. ochraceus, A. repens, and Penicillium funiculosum and complexes of P. citrinum-P. implicatum isolated from moldy pecan meats were toxic to chicks. 相似文献
73.
R. B. Singh Ben W. Smith 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1971,41(8):360-364
Summary Cytogenetic studies were made with particular emphasis on the sex-determining mechanism in Rumex acetosella (6 x = 42) and its hybrids (F
1, F
2, BC
1 and BC
2) with R. hastatulus (synthetic 4 x = 16 = 4 A +4 X = and 4 x = 18 = 4 A + 2 (X Y
1
Y
2) = ). Rumex acetosella was almost strictly dioecious with 5050 male and female. Breeding tests revealed that the males were heterogametic. The longest chromosomes (S), usually two, are the sex chromosomes of this hexaploid species. The S chromosomes are homomorphic in both male and female. The sex chromosome: autosome ratios, and the strong epistatic male effect of the S
M chromosome in the polyploid dioecious species and in the hybrids, are evidence of an X/Y Melandrium type sex-determining mechanism controlled by a single pair of homomorphic sex chromosomes. Thus, the sex chromosome formula of the males was S
F
S
M and that of females was S
F
S
F. The present approach is a new method for resolving the sex-determining mechanism in a dioecious species. 相似文献
74.
J. B. Donnelly J. J. Lynch M. E. D. Webster 《International journal of biometeorology》1974,18(3):233-247
Heart rates, respiratory rates, body temperatures, ad libitum ‘day’ and ‘night’ food consumption and body weight changes have been examined in 15 mature Merino wethers shorn in moderate environmental conditions. All sheep showed a depression in food consumption for two days after shearing. Sheep that gained weight during the next three weeks then increased their food consumption at night by approximately 30% although the average daily consumption was only increased by 5%. Sheep that lost weight showed a depressed food consumption throughout the three week period after shearing. Marked increases in the temperature difference between ear skin and air as well as thermal tachypnoea during the warmest period of the day were recorded in all sheep 14–16 days after shearing. This indicated that the critical temperature for all sheep had decreased by about 10°C. These signs of acclimatisation appeared at similar times in all sheep, suggesting that increased resistance to body cooling developed at similar rates in weight gain and weight loss sheep and independent of the origin of body heat production. The results of the investigations are discussed in relation to the concept that the initial response to cold stress includes a depression in food intake and that the duration of this depression is a function of the cold stimulus and the strain it induces in the sheep. 相似文献
75.
76.
Nucleocapsids released from influenza virions by sodium deoxycholate sedimented heterogeneously in sucrose gradients. Highly infectious virus (complete) preparations yielded nucleocapsids with peak distributions at 64 and 56S; von Magnus type virus (incomplete) lacked 64S nucleocapsids. Treatment of influenza virus nucleocapsids with pancreatic ribonuclease rendered the associated viral ribonucleic acid (RNA) molecules acid-soluble, indicating that capsid proteins do not completely surround the viral RNA's. However, the capsid proteins remained associated after enzymatic hydrolysis of the RNA, as judged by persistently high sedimentation rates. Sedimentation rates of viral nucleocapsids reflected the sedimentation rates of the associated RNA's: 64S nucleocapsids contained 18S RNA, whereas 56S nucleocapsids contained 15S RNA, although in both cases RNA's sedimenting at 4 to 13S were also recovered. Furthermore, just as incomplete virions lacked 64S nucleocapsids, they also lacked 18S RNA. These findings support the hypothesis that the influenza virus genome is divided among several distinct pieces of RNA. 相似文献
77.
Procedure for Evaluating the Effects of 2,450- Megahertz Microwaves upon Streptococcus faecalis and Saccharomyces cerevisiae 总被引:5,自引:4,他引:1
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Modifications of a commercial 2,450-megahertz microwave oven were made so that 6 ml of microbial suspension could be exposed to the microwave field for various periods of time. The microorganisms were contained in the central tube of a modified Liebig condenser positioned in the approximate geometric center of the oven cavity. Kerosene at -25 C was circulated through the jacket of the condenser during microwave exposure permitting microwaves to reach the microbial suspension. Flow rates of the kerosene were varied to permit the temperature of the suspension to range from 25 to 55 C during microwave exposure. Conductive heating experiments using similar temperatures were also conducted. A thermocouple-relay system was employed to measure the suspension temperature immediately after the magnetron shutoff. Continuous application of microwaves to suspensions of 10(8) to 10(9)Streptococcus faecalis or Saccharomyces cerevisiae per ml appeared to produce no lethal effects other than those produced by heat. Respiration rates of microwave-exposed Scerevisiae were directly related to decreases in viable count produced by increased microwave exposure times. 相似文献
78.
79.
On the site of action of phosphatide acyl-hydrolase activity of rat brain homogenates on lecithin 总被引:3,自引:3,他引:0
The hydrolysis of 2- [14C]acyl-labelled and [Me-3H]choline-labelled lecithins by rat brain homogenates has been studied. The acyl-labelled substrate was hydrolysed with the production of both radioactive lysolecithin and radioactive free fatty acid in the proportions of 60 per cent and 40 per cent; traces of labelled mono- and diglyceride were also formed. In addition to radioactive lysolecithin the [3H]choline-labelled lecithin also gave rise to much smaller amounts of radioactive water soluble derivatives, consisting almost entirely of free choline and phosphorylcholine with only traces of glycerylphosphorylcholine. The results provide evidence for the production of a mixture of 1- and 2-acyl isomers of lysolecithin by phospholipase action in brain homogenates at pH 7.4, the latter predominating slightly. 相似文献
80.