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1.
The in vitro secretion of aldosterone and corticosterone by the adrenal glands of fetal (day 30), pregnant and non-pregnant rabbits was examined under basal and stimulated conditions. In general, non-pregnant animals basally secreted less aldosterone than either pregnant or fetal rabbits, whereas basal corticosterone secretion by pregnant animals exceeded that of either fetal or non-pregnant animals. At similar doses of adrenocorticotropin (ACTH), fetal and pregnant adrenal glands produced comparatively more aldosterone than non-pregnant animals, while corticosterone secretion was accelerated to a greater degree in fetal rabbits than in the other groups. Angiotensin II had its greatest effect on the aldosterone secretory rates of fetal and non-pregnant animals without affecting corticosterone secretion in any group. Elevated potassium (K+) enhanced the secretory rates of aldosterone and corticosterone in fetal animals, while increasing only aldosterone secretion in non-pregnant rabbits. Serotonin accelerated aldosterone secretion in all animals, whereas it increased corticosterone secretion only in non-pregnant animals. These results suggest that (1) in fetal rabbits, the secretory rates of both aldosterone and corticosterone are regulated primarily by ACTH and to a much lesser extent by angiotensin II and K+, (2) the corticosterone secretory rates of pregnant and non-pregnant rabbits are controlled mainly by ACTH, and (3) aldosterone secretion by non-pregnant animals is regulated primarily by angiotensin II and secondarily by ACTH and K+, while in pregnant animals ACTH may be the primary regulator of aldosterone secretion as it is in the fetus.  相似文献   

2.
Bovine type M pyruvate kinase can be reversibly denatured by solutions of guanidine HCl. Subsequent dilution of the enzyme into buffer containing β-mercaptoethanol or dithiothreitol results in recovery of enzymatic activity with an average half-time of 17 min at 16 °C. The addition of 1 mm l-phenylalanine increases the average half-time for recovery of enzymatic activity to 26 min, while 8 mm l-phenylalanine further increases this value to 46 min. Tyrosine and tryptophan also inhibit the reactivation but to a lesser extent than phenylalanine. Neither l-alanine, l-valine, d-phenylalanine, phosphoenolpyruvate, nor fructose 1,6-bisphosphate have any appreciable effect on activity recovery rates, either in the presence or absence of l-phenylalanine. Phenylpyruvate is a very potent inhibitor of reactivation. The addition of 5 mm phenylpyruvate increases the half-time to 57 min. The evidence presented in this paper supports the hypothesis that an l-phenylalanine-binding site which probably is distinct from the catalytic site is formed early in the renaturation process. l-Phenylalanine binds to this site and inhibits two first-order relaxations that are rate limiting for the reactivation and that have the following rate constants: 8.76 × 10?2 and 1.24 × 10?2 min?1, respectively, in the absence of phenylalanine and 3.04 × 10?2 and 7.63 × 10?3min?1, respectively, in the presence of 8.0 mm phenylalanine. We presume these first-order processes to be transconformational steps in the reactivation process.  相似文献   

3.
Maternal docosahexaenoic acid (DHA, 22:6n-3) supplies the developing fetus during pregnancy; however, the mechanisms are unclear. We utilized pregnant rats to determine rates of DHA accretion, tissue unesterified DHA uptake and whole-body DHA synthesis-secretion. Female rats maintained on a DHA-free, 2% α-linolenic acid diet were either:1) sacrificed at 56 days for baseline measures, 2) mated and sacrificed at 14–18 days of pregnancy or 3) or sacrificed at 14–18 days as age-matched virgin controls. Maternal brain, adipose, liver and whole body fatty acid concentrations was determined for balance analysis, and kinetic modeling was used to determine brain and liver plasma unesterified DHA uptake and whole-body DHA synthesis-secretion rates. Total liver DHA was significantly higher in pregnant (95±5 μmol) versus non-pregnant (49±5) rats with no differences in whole-body DHA synthesis-secretion rates. However, liver uptake of plasma unesterified DHA was 3.8-fold higher in pregnant animals compared to non-pregnant controls, and periuterine adipose DHA was lower in pregnant (0.89±0.09 μmol/g) versus non-pregnant (1.26±0.06) rats. In conclusion, higher liver DHA accretion during pregnancy appears to be driven by higher unesterified DHA uptake, potentially via DHA mobilization from periuterine adipose for delivery to the fetus during the brain growth spurt.  相似文献   

4.
The enhancement of electrical activity of the neurosecretory cells in the brain and corpus cardiacum of Rhodnius prolixus induced by 20-hydroxyecdysone has been used as a means of examining the role of aminergic neurons in this reflex. The response of the brain and corpus cardiacum from mated ovariectomized females to 20-hydroxyecdysone was blocked by phentolamine and phenoxybenzamine (α-aminergic receptor antagonists) but not by propranolol (a β-aminergic receptor antagonist). Preparations taken from ‘reserpinzed’ females failed to respond to 20-hydroxyecdysone. Dopamine at 10?7 M was capable of mimicking 20-hydroxyecdysone in activating the neurosecretory system from mated ovariectomised females as well as from ‘reserpinized’ mated ovariectomised females. The response to dopamine was blocked by phentolamine. The neurosecretory system from virgin ovariectomized females failed to respond to 10?7 or 10?6 M dopamine, but was activated by 10?5 M dopamine.It is concluded that the action of 20-hydroxyecdysone onto the neurosecretory cells is indirect and involves aminergic interneurons. The results also suggest that the mating stimuli may function by enhancing the response of neurons to amines.  相似文献   

5.
In non-pregnant female and pregnant rats the concentration (0.41 mumoles/ml and 0.49 mumoles/ml), the turnover time (0.6 min and 0.8 min), and the irreversible disposal rate (8 mumoles/min and 7 mumoles/min) of plasma free fatty acids (FFA) were determined. The results indicate that there are no major differences in the metabolism of the plasma FFA between non-pregnant female and pregnant rats.  相似文献   

6.
A reliable Agrobacterium-mediated transformation and shoot regeneration protocol was developed for breeding lines of commercially important western-shipper cantaloupe and honeydew melons, ‘F39’ and ‘150’, respectively. Different media were tested to select a shoot regeneration system for each of three elite breeding lines ‘F39’, ‘141’ and ‘TMS’. Murashige &; Skoog (MS) basal medium supplemented with 1 mg l?1 benzyladenine (BA), 0.26 mg l?1 abscisic acid (ABA) and 0.8 mg l?1 indole-3-acetic acid (IAA) was used for shoot regeneration from cotyledonary explants in ‘F39’ and ‘150’. Kanamycin sensitivity as well as Timentin? and Clavamox® were evaluated using wild-type ‘F39’ and ‘150’ cotyledons. Kanamycin concentrations of 200 and 150 mg l?1 were chosen as the threshold levels for ‘F39’ and ‘150’, respectively. No significant differences were found between Timentin? and Clavamox® in ‘F39’; however, Clavamox® reduced the incidence of vitrification and increased the frequency of shoot elongation in ‘150’. A. tumefaciens strain EHA105, harboring pCNL56 carrying neomycin phosphotransferase II (nptII) and gusA reporter genes, was selected to establish a transformation protocol for ‘F39’ and ‘150’. Putative transformants were evaluated using β-glucuronidase (GUS) histochemical assay, polymerase chain reaction (PCR) and Southern blot analyses. Based on these parameters, the transformation efficiency for cantaloupe ‘F39’ was 0.3% and that for honeydew ‘150’ was 0.5%.  相似文献   

7.
Wild-caught female harbor seals ( Phoca vitulina ) were classified as sexually mature or immature on the basis of standard body length (< 125 cm immature, > 125 cm mature) and plasma progesterone concentrations measured using an enzyme-linked immunosorbent assay (ELISA), a technique usable in the field. Sexually mature females were classified as pregnant or non-pregnant on the basis of their plasma progesterone concentrations. Of 28 wild mature female harbor seals caught in the Moray Firth, N.E. Scotland, between the end of February and the end of May, 79% had plasma progesterone concentrations greater than 60 nmol liter−1, the lowest plasma progesterone concentration measured in one of eight females later observed with a pup, and were diagnosed as pregnant. A linear discriminant function, calculated to provide a method of distinguishing pregnant and non-pregnant females, predicted 100% of non-pregnant females and 95.8% of pregnant females using plasma progesterone concentration, standard length, and month of capture as parameters. Plasma progesterone concentrations were less than 30 nmol liter−1 in all mature and immature males and immature females. In mature females plasma progesterone concentrations ranged from 0-318 nmol liter−1.  相似文献   

8.
The plasma clearance rate of 3H-TdR was determined by thin-layer chromatography of samples from pregnant rhesus monkeys who had received a single intravenous injection of 3H-TdR. At 10 min after the injection the circulating levels of 3H-TdR had fallen to less than 0.2% of the initial theoretical distribution of the label. In general the plasma clearance rate can be described by a ‘double exponential’curve with half-lives of 1 min and 20 min. Thus, 3H-TdR disappears from the circulation of the pregnant monkey more rapidly than it does from the bloodstream of rodents, which correlates with previously detected interspecies differences in autoradiographic labeling of neurons. This means (1) that higher doses of 3H-TdR must be used for autoradiographic labeling of monkey tissues and (2) that the monkey may be useful for studying cell kinetics because it has a short pulse labeling of the DNA.  相似文献   

9.
Immunoglobulin M and G levels in bovine Trypanosoma vivax infection were compared in non-pregnant, first, second and third trimester pregnant heifers. All the infected heifers showed a significant rise in IgM levels when compared to the non-infected controls. 7–8 fold increases were recorded. There were however differences in the rate of increases and ability to maintain peak level response (P <0.01) between the groups. Infected pregnant heifers in the first and second trimester responded better than infected non-pregnant and infected heifers in the third trimester pregnancy. In all the groups, the differences between the infected and control heifers were highly significant (P <0.001). The IgG levels showed a similar pattern of increases in infected heifers though response was gradual. In the different groups 1.4–2.5-fold increases were recorded. These were significantly different from levels in the control (P <0.01). Again, pregnant heifers responded better than non-pregnant heifers except those in the third trimester pregnancy. The results correlated with the observation that given the same conditions, clinical manifestation of T. vivax infection is more severe in non-pregnant than in pregnant heifers except those in advanced pregnancy.  相似文献   

10.
G W Kittinger 《Steroids》1974,23(2):229-243
Four pregnant rhesus monkeys cnd their fetuses. were infused constantly with 14C-cortisol and 3H-cortisol. Steady state plasma specific activities for 14C and 3H-cortisol were obtained after 80 to 90 minutes in both mother and fetus. These data and the rates of infusion of radioactivity were used to calculate the following parameters for both mother and fetus: 1) metabolic clearance rates, 2) production rates, 3) mean adrenal secretory rates, 4) transfer rates from mother to fetus and fetus to mother cnd, 5) the fraction of cortisol in each vascular compartment derived from the maternal and fetal edrenals. Plasma cortisone concentrations, as well as the fraction of cortisone derived from fetal and maternal cortisol were determined. Tetrahydrocortisol and tetrahydrocortisone concentrations were calculated. Mean cortisol secretory rates for the maternal and fetal adrenals were 60.0±11.8 and 1.82±0.42 mg/day. Fifty-eight % of the cortisol in the fetal compartment was of maternal origin. During transfer across the placenta to the fetus, cortisol was largely converted to cortisone. In fetal plasma 76% of the cortisone was of maternal origin. Cortisone concentrations in fetal plasma were higher than those of cortisol.  相似文献   

11.
Abstract The rates of uptake of nitrate-N per unit length; surface area and volume of root were measured in solution depletion experiments conducted in a root laboratory, using intact roots of two 4.5-year-old apple trees (Discovery/M.9 and Worcester Pearmain/M.9) at two different depths in the soil profile. In Discovery/M.9, NO3? uptake rate per unit root was constant over the 20-200 mmol m?3 range of solution concentration. In Worcester/M.9, the uptake rate per unit root over the 200-150 mmol m?3 range (corresponding to a ‘lag’ phase) was lower than that over 150-20 mmol m?3. The uptake rates after the lag phase at depths of 46 and 104 cm were ca. 1.3 and 5.0 times greater than those in Discovery/M.9 at the 46 and 110 cm depths, respectively. The concentration below which net uptake was zero was ca. 1 mmolm?3. In Discovery/M.9, the uptake rate per unit root at the 46cm depth was about 2.8 times that at 110 cm whereas in Worcester/M.9, the uptake rates at 46cm depth were about 1.8 and 1.4 times lower than those at 104cm over the solution concentration ranges 200-150 and 150-20 mmol m?3, respectively. Only small differences were observed in uptake rates per unit root between 1400-1700 h, 2400-0400 h, and 0700-1100 h. For successive 5°C-increments in root temperature between 5 and 25° C, the nitrate uptake rate per unit root increased by 130, 10, 30 and 5%, respectively. A major change in the activation energy for nitrate uptake was observed at a transition temperature located between 5°and 10°C.  相似文献   

12.
The present study was carried out to investigate whether the P concentration in the roots or the shoots controls the growth and citrate exudation of cluster roots in white lupin (Lupinus albus L). Foliar P application indicated that low P concentration in the shoots enhanced cluster‐root growth and citrate‐exudation rate more so than low P concentration in the roots. In the split‐root study, the P concentration in the shoots increased with increased P supply (1, 25 or 75 mmol m?3 P), to the ‘privileged’ root halves. Roots ‘deprived’ of P invariably had the same low P concentrations, whereas those in the ‘privileged’ roots increased with increasing P supply (1, 25 or 75 mmol m?3 P). Nevertheless, the proportion of the total root mass allocated to cluster roots, and the citrate‐exudation rates from the root halves were always similar on both root halves, irrespective of P supply, and decreased with increasing shoot P concentrations. Peak citrate exudation rates from developing cluster roots were significantly faster from cluster roots on the ‘deprived’ root halves when the ‘privileged’ half was exposed to 1 mmol m?3 P as compared with 25 or 75 mmol m?3 P. The possibility that changes in the concentrations of P fractions in the root halves influenced cluster‐root growth and citrate exudation was discounted, because there were no significant differences in insoluble organic P, ester‐P and inorganic P among all ‘deprived’ root halves. The results indicate that cluster‐root proportions and citrate exudation rates were regulated systemically by the P status of the shoot, and that P concentrations in the roots had little influence on growth and citrate exudation of cluster roots in L. albus.  相似文献   

13.
Porcine muscle lactic dehydrogenase can be reversibly dissociated into monomers at high hydrostatic pressure. The rate of dissociation depends on the conditions of the solvent (Schade et al., 1980, Biochemistry, in press). Maximum yields of reactivation are achieved after dissociation by 20 min incubation in 0.2 M Tris/HCl buffer or 0.2 M KCl at pH 7.6, in the presence of 10 mM dithioerylhritol and 1 mM EDTA, provided that both dissociation and reassociation are performed under anaerobic conditions. At enzyme concentrations of the order of 1 μM reactivation amounts to 9?5%/, the product of reac- tivation being indistinguishable from the enzyme in its initial native state. Based on the long-term stability of the enzyme under the optimum given conditions of reactivation, the kinetics of reconstitution after pressure release were investigated over a wide range of enzyme concentrations (1 nM < c < 1 μM). The weakly sigmoidal kinetics may be described by an irre- versible uni-bimolecular reaction scheme, corresponding to a sequential transconformation-association process. Assuming the protomers to be enzymatically inactive, the kinetic profiles may be fitted by one set of kinetic constants: kuni = 1.5 × 10?2 s?1and kbi = 7 × 103 s?1 M?1, the association step belonging to either dimer or tetramer formation.  相似文献   

14.
A practical and economic method for the quantification of testosterone-estradiol-binding globulin TeBG is described. The procedure premits the differentiation without overlap of the TeBP levels in males, non-pregnant females and during pregnancy. Mean titles were 1/5, 1/93 and 1/360 respectively. During pregnancy, we found high levels of TeBG and increased plasma testosterone, with mean values of 143.4 nanograms/100 ml. We have found no significant differences in TeBG levels, or in maternal blood testosterone levels in relation to fetal sex; however, plasma testosterone levels were significantly different among new born of different sex, with mean values of 96.25 nanograms per cent for males and 78.21 nanograms per cent for females.  相似文献   

15.
Proper management of threatened species requires knowledge of population sizes and structures, however current techniques to gather this information are generally impractical and costly and can be stressful on the animals. Non-invasive methods that can produce high quality and accurate results are better alternatives. In winter 2010, we collected blood and fecal samples from 2 reindeer (Rangifer tarandus) populations (Kaamanen, Finland and Svalbard, Norway) to investigate the feasibility of using fecal progesterone metabolites to help estimate the reproductive status, the sex, and the age structures of the populations. We first examined the relationship between plasma progesterone and fecal progesterone metabolite concentrations. We further assessed whether fecal progesterone metabolite levels would clearly differ among calf, yearling, and adult and between pregnant and non-pregnant females. We quantified fecal progesterone metabolites (using enzyme immunoassay) and plasma progesterone (using radio immunoassay) of females and males of different ages from the 2 herds. We found in both populations that fecal progesterone metabolite levels reflected plasma progesterone concentrations. However, the range of fecal progesterone metabolite concentration was much wider in Finland than in Svalbard, possibly due to differences in diet or body condition. We determined a threshold value of 1.31 ng/ml plasma progesterone and 2025.93 ng/g dried fecal progesterone metabolites to identify pregnant reindeer from non-pregnant animals with 100% accuracy. We found a significant difference in fecal progesterone metabolite concentrations only between calves and yearlings/adults in Finland. We could not differentiate among males, non-pregnant adults, or calves of either sex; therefore identification of sex may have to rely on the use of DNA techniques. Our results suggest that hormone concentration, in combination with fecal DNA and pellet morphometry techniques, may provide important population parameters and is a valuable tool for the monitoring of reindeer and may have an application for threatened populations of woodland caribou throughout the winter and early spring. © 2011 The Wildlife Society.  相似文献   

16.
Summary— The purpose of the present study was to investigate potential modulations of endothelial cells of the bovine corpus luteum (CL) during pregnancy. Luteal endothelia of pregnant and non-pregnant cows were isolated and purity of cultures was verified by flow cytometric quantification of three independent endothelial markers (von Willebrand factor, angiotensin converting enzyme, Bandeiraea simplicifolia agglutinin I ligands). Different cellular parameters including light and electron microscopical investigation of morphology and growth characteristics as well as quantification of cellular lectin binding sites were compared. Extensive heterogeneity between luteal endothelial cells in pregnant and non-pregnant animals could be demonstrated, reflected in functional attributes like angiogenic activity, ultrastructural characteristics and the quantitative expression of cellular carbohydrates. Two different morphological types of cells (‘cobblestone growth pattern’ and ‘arcuate growth pattern’) were isolated from the CL of pregnancy as well as from the cyclic CL. Spontaneous angiogenic activities, including cellular migration in band-like structures and formation of ring-like structures, were observed in endothelial cells isolated from the CL of pregnant cows exclusively. This strongly suggests that microvascular luteal endothelium of pregnant animals, in contrast to the one of non-pregnant animals, is able to produce quantitatively and/or qualitatively specific angiogenesis factor(s). Heterogeneity between luteal endothelial cells in the pregnant and non-pregnant animal could also be demonstrated by quantification of lectin (Bandeiraea simplicifolia agglutinin I, concanavalin A, Dolichos biflorus agglutinin, Ulex europaeus agglutinin I, wheat germ agglutinin) binding sites: quantitative expression of specific endothelial cell surface carbohydrates could be correlated to be status of pregnancy, thus emphasizing the actual need of quantification of lectin binding.  相似文献   

17.
Bioenergy crops have a secondary benefit if they increase soil organic C (SOC) stocks through capture and allocation below-ground. The effects of four genotypes of short-rotation coppice willow (Salix spp., ‘Terra Nova’ and ‘Tora’) and Miscanthus (M.?×?giganteus (‘Giganteus’) and M. sinensis (‘Sinensis’)) on roots, SOC and total nitrogen (TN) were quantified to test whether below-ground biomass controls SOC and TN dynamics. Soil cores were collected under (‘plant’) and between plants (‘gap’) in a field experiment on a temperate agricultural silty clay loam after 4 and 6 years’ management. Root density was greater under Miscanthus for plant (up to 15.5 kg m?3) compared with gap (up to 2.7 kg m?3), whereas willow had lower densities (up to 3.7 kg m?3). Over 2 years, SOC increased below 0.2 m depth from 7.1 to 8.5 kg m?3 and was greatest under Sinensis at 0–0.1 m depth (24.8 kg m?3). Miscanthus-derived SOC, based on stable isotope analysis, was greater under plant (11.6 kg m?3) than gap (3.1 kg m?3) for Sinensis. Estimated SOC stock change rates over the 2-year period to 1-m depth were 6.4 for Terra Nova, 7.4 for Tora, 3.1 for Giganteus and 8.8 Mg ha?1 year?1 for Sinensis. Rates of change of TN were much less. That SOC matched root mass down the profile, particularly under Miscanthus, indicated that perennial root systems are an important contributor. Willow and Miscanthus offer both biomass production and C sequestration when planted in arable soil.  相似文献   

18.
19.
Oxime reactivators are the drugs of choice for the post-treatment of OP (organophosphorus) intoxication and used widely for mechanistic and kinetic studies of OP-inhibited cholinesterases. The purpose of the present study was to evaluate new oxime compounds to reactivate acetylcholinesterase (AChE) inhibited by the OP paraoxon. Several new bisquaternary pyridinium oximes with heterocyclic linkers along with some known bisquaternary pyridinium oximes bearing aliphatic linkers were synthesized and evaluated for their in vitro reactivation potency against paraoxon-inhibited electric eel acetylcholinesterase (EeAChE) and recombinant human acetylcholinesterase (rHuAChE). Results herein indicate that most of the compounds are better reactivators of EeAChE than of rHuAChE. The reactivation potency of two different classes of compounds with varying linker chains was compared and observed that the structure of the connecting chain is an important factor for the activity of the reactivators. At a higher concentration (10?3 M), compounds bearing aliphatic linker showed better reactivation than compounds with heterocyclic linkers. Interestingly, oximes with a heterocyclic linker inhibited AChE at higher concentration (10?3 M), whereas their ability to reactivate was increased at lower concentrations (10?4 M and 10?5 M). Compounds bearing either a thiophene linker 26, 46 or a furan linker 31 showed 59%, 49% and 52% reactivation of EeAChE, respectively, at 10?5 M. These compounds showed 14%, 6% and 15% reactivation of rHuAChE at 10?4 M. Amongst newly synthesized analogs with heterocyclic linkers (2635 and 4546), compound 31, bearing furan linker chain, was found to be the most effective reactivator with a kr 0.042 min?1, which is better than obidoxime (3) for paraoxon-inhibited EeAChE. Compound 31 showed a kr 0.0041 min?1 that is near equal to pralidoxime (1) for paraoxon-inhibited rHuAChE.  相似文献   

20.
The use of a small number of cultivars in agriculture can lead to a loss of agrobiodiversity. Since in vitro techniques are valuable tools for conserving plant biodiversity, an efficient micropropagation protocol for four Italian hazelnut cultivars, ‘Carrello’, ‘Ghirara’, ‘Minnulara’, and ‘Panottara’, was developed. The highest axillary bud survival was obtained after decontamination with 40?min 1% sodium hypochlorite followed by 40?min 0.1% sodium merthiolate in ‘Minnulara’ and ‘Ghirara’, while the 35?+?35?min treatment was the best for ‘Carrello’ and ‘Panottara’. Shoot multiplication was higher in ‘Minnulara’ and ‘Ghirara’ when 6.6?μM N6-benzyladenine was used, even if some hyperhydric shoots were observed, while metatopolin was more effective in the other two cultivars. In vitro rooting, performed in ‘Carrello’ and ‘Panottara’, was higher with 17.6 than with 9.8 µM indole-3-butyric. Following in vitro root induction with 17.6 µM indole-3-butyric acid for 7 days, rooting and acclimatisation in greenhouse exceeded 85% for all four cultivars.  相似文献   

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