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11.
A hierarchical response to differences in ration size in the reproductive performance of female three-spined sticklebacks 总被引:3,自引:0,他引:3
The response of female three-spined sticklebacks ( Gasterosteus aculeatus ) to differences in food ration during the breeding season was quantified for several variables related to reproductive performance. The measured protein and lipid contents (mg g−1 ) of eggs were unaffected by ration. Egg size increased with an increase in both ration and female size, but the proportional increase in egg size was much smaller than the proportional increase in ration. The best predictor of mean batch (clutch) fecundity and weight was female size. There was a small but significant increase in batch fecundity with ration, but the increase was not directly proportional to the increase in ration. The rate of spawning, total breeding season fecundity and total weight of eggs spawned over the breeding season were sensitive to ration with breeding season fecundity and weight increasing in direct proportion to ration. Thus, in female sticklebacks, there is a hierarchy of sensitivity to ration in the response of variables related to reproduction. 相似文献
12.
Kinetics of cytosolic Ca2+ concentration after photolytic release of 1-D-myo-inositol 1,4-bisphosphate 5-phosphorothioate from a caged derivative in guinea pig hepatocytes. 总被引:1,自引:1,他引:0 下载免费PDF全文
J. F. Wootton J. E. Corrie T. Capiod J. Feeney D. R. Trentham D. C. Ogden 《Biophysical journal》1995,68(6):2601-2607
The influence of 1-D-myo-inositol 1,4,5-trisphosphate (InsP3) breakdown by InsP3 5-phosphatase in determining the time course of Ca2+ release from intracellular stores was investigated with flash photolytic release of a stable InsP3 derivative, 5-thio-InsP3, from a photolabile caged precursor. The potency and Ca(2+)-releasing properties of the biologically active D isomers of 5-thio-InsP3 and InsP3 itself were compared by photolytic release in guinea pig hepatocytes. After a light flash, cytosolic free calcium concentration ([Ca2+]i) showed an initial delay before rising quickly to a peak and declining more slowly to resting levels, with time course and amplitude generally similar to those seen with photolytic release of InsP3. Differences were a three- to eightfold lower potency of 5-thio-InsP3 in producing Ca2+ release, much longer delays between photolytic release and Ca2+ efflux with low concentrations of 5-thio-InsP3 than with InsP3, and persistent reactivation of Ca2+ release, producing periodic fluctuations of cytosolic [Ca2+]i with high concentrations of 5-thio-InsP3 but not InsP3 itself. The lower potency of 5-thio-InsP3 may be a result of a lower affinity for closed receptor/channels or a lower open probability of liganded receptor/channels. The longer delays with 5-thio-InsP3 at low concentration suggest that metabolism of InsP3 by 5-phosphatase may reduce the concentration sufficiently to prevent receptor activation and may have a similar effect on InsP3 concentration during hormonal activation.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
13.
Synopsis Parental investment is the cost of providing parental care. The short-term cost of parental care was measured in the biparental
substrate nesting cichlid,Cichlasoma nigrofasciatum, by comparing the expected future survival (measured indirectly as energy content of the body), time taken to breed again
and, among females, the number of eggs produced at a subsequent spawning of parental and non-parental pairs. In comparison
with non-parental pairs, parental pairs took significantly longer to respawn. Body condition and female fecundity were unaffected
after a single parental cycle. The effect on parental cost and expenditure of factors likely to stress the parental fish was
also investigated. Removing the male parent had no effect on female parental cost. Exposing pairs to potential predators of
offspring increased the time taken by pairs to respawn. In parental males, reducing the level of feeding gave rise to a reduction
in some care behaviours. 相似文献
14.
The operational sex ratio (OSR), an important determinant of the intensity of sexual selection, can vary with the population sex ratio and the potential reproductive rates of males and females. In parental teleosts, different forms of brood cannibalism, filial and non-kin, could affect the potential reproductive rates of males and females, and thereby the OSR. The direction of the effect of brood cannibalism on the OSR would depend on the sex of the cannibal and the parent. No evidence has been found that brood cannibalism can affect the OSR by altering the sex ratio. 相似文献
15.
The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria 总被引:1,自引:0,他引:1
Raymond Wootton 《FEBS letters》1984,178(2):187-192
In a recent communication Lehninger and co-workers (Costa, L.E., Reynaferje, B., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 4802-4811) reported values approaching 8 for the H+/O ratio of vectorial proton ejection from rat liver mitochondria respiring with succinate. Here we present a rigorous analysis of these measurements which reveals that they may significantly overestimate the true H+/O stoicheiometry. 相似文献
16.
A Torre-Blanco E Adachi Y Hojima J A Wootton R R Minor D J Prockop 《The Journal of biological chemistry》1992,267(4):2650-2655
Previous observations suggested that incubating fibroblasts at elevated temperature caused over-modification of type I procollagen by post-translational enzymes because of a delay in folding of the collagen triple helix. Here, human skin fibroblasts were incubated at 40.5 instead of 37 degrees C, and the type I procollagen secreted into the medium was isolated. Analysis of the protein indicated that there was an increase of about 5 residues of hydroxylysine/alpha chain and about 1 residue of glycosylated hydroxylysine/alpha chain. Assays with procollagen N-proteinase indicated that the N-propeptide of the over-modified collagen was cleaved at a decreased rate, apparently because the over-modification altered the conformation-dependent cleavage site for the enzyme. Assays in a system for assembly of collagen into fibrils demonstrated that the over-modified protein had a higher critical concentration for self-assembly. Also, the fibrils formed from the over-modified collagen at 31 and 29 degrees C had smaller diameters than fibrils formed from normal type I collagen. The results provide direct evidence for earlier suggestions that post-translational over-modification of a fibrillar collagen can alter the morphology of the fibrils formed. The results also indicate that some of the biological consequences of the mutations in type I procollagen causing heritable disorders must be ascribed to the effects of post-translational over-modifications that frequently occur as secondary consequences of changes in the primary structure of the protein. 相似文献
17.
A mutation in the pro alpha 2(I) gene (COL1A2) for type I procollagen in Ehlers-Danlos syndrome type VII: evidence suggesting that skipping of exon 6 in RNA splicing may be a common cause of the phenotype. 总被引:5,自引:4,他引:1 下载免费PDF全文
N S Vasan H Kuivaniemi B E Vogel R R Minor J A Wootton G Tromp R Weksberg D J Prockop 《American journal of human genetics》1991,48(2):305-317
Fibroblasts from a proband with Ehlers-Danlos syndrome type VII synthesized approximately equal amounts of normal and shortened pro alpha 2(I) chains of type I procollagen. Nuclease S1 probe protection experiments with mRNA demonstrated that the pro alpha 2(I) chains were shortened because of a deletion of most or all of the 54 nucleotides in exon 6, the exon that contains codons for the cleavage site for procollagen N-proteinase. Sequencing of genomic clones revealed a single-base mutation that converted the first nucleotide of intron 6 from G to A. Therefore, the mutation was a change, in the -GT-consensus splice site, that produced efficient exon skipping. Allele-specific oligonucleotide hybridizations demonstrated that the proband's mother, father, and brother did not have the mutation. Therefore, the mutation was a sporadic one. Analysis of potential 5' splice sites in the 5' end of intron 6 indicated that none had favorable values by the two commonly employed techniques for evaluating such sites. The proband is the fourth reported proband with Ehlers-Danlos syndrome VII with a single-base mutation that causes skipping of exon 6 in the splicing of RNA from either the COL1A1 gene or COL1A2 gene. No other mutations in the two type I procollagen genes have been found in the syndrome. Therefore, such mutations may be a common cause of the phenotype. The primers developed should be useful in screening for the same or similar mutations causing the disease. 相似文献
18.
In a population of Gasterosteus aculeatus living in an infertile, upland lake, the fish bred at the age of one year and few survived to breed again. The highest growth rates were achieved in the first month of life, but in comparison with other populations of G. aculeatus growth was slow during the autumn and ceased during the winter. But in spring and early summer, there was a spurt in the growth rate.
Laboratory studies provided regression models for the prediction of the rate of food consumption from measurements of growth. The estimates of the consumption rate indicated the effect of the growth in body size and seasonal variations during the first year of life. It was estimated that a fish of mean length in the population consumed 3150 mg of food in a year in which it grew from 65.8 to 552.0 mg, with an overall gross growth efficiency of 15.4%.
The study illustrated the integration of laboratory and field studies to obtain reasonable estimates of the rate of food consumption by fish throughout their first year of life. 相似文献
Laboratory studies provided regression models for the prediction of the rate of food consumption from measurements of growth. The estimates of the consumption rate indicated the effect of the growth in body size and seasonal variations during the first year of life. It was estimated that a fish of mean length in the population consumed 3150 mg of food in a year in which it grew from 65.8 to 552.0 mg, with an overall gross growth efficiency of 15.4%.
The study illustrated the integration of laboratory and field studies to obtain reasonable estimates of the rate of food consumption by fish throughout their first year of life. 相似文献
19.
Seven defective variants of the NADP-specific glutamate dehydrogenase of Neurospora crassa, resulting from missense mutations in the am gene, are quantitatively different from the wild type enzyme in the allosteric equilibrium between enzymically active A and inactive I conformations, and in the kinetics of conformational transitions between these states. These abnormalities have been defined using measurements of enzymic activity and of the intrinsic tryptophan fluorescence emission of the proteins.The protein from am1(Ser336 → Phe) is hyperstable in the A conformation but this state is enzymically inactive because it fails to bind coenzyme. The other six variants are potentially active but are, to different extents, hyperstable in the I conformation. They form a series of analogues, those of am131 (substitution not determined), am130(Pro75 → Ser), am3(Glu393 → Gly), am2(His142 → Gln), am19(Lys141 → Met) in order of increasing abnormality of the equilibrium position. am122(Trp389 changed to an undetermined residue) resembles am19. The hyperstability is sufficient to explain the auxotrophy of am The proteins of am131 and am130 are, in addition, abnormally prone to denaturation. These hyperstabilities of the I state are small in free energy terms, consistent with the fact that the defects of some variants may be corrected or partially corrected by second site substitutions or by complementation in hybrid hexamers with am1 protein.Five out of seven amino acid substitutions known to affect this equilibrium (including Gln391 → Arg of revertant am1924) involve charged residues clustered around positions 141 and 391. Interactions between these two parts of the polypeptide are implicated in stabilizing the A state of the enzyme, possibly by providing protonatable groups or part of the dicarboxylate binding site, and in affecting the environment of a tryptophan residue responsible for the fluorescence difference of the two conformations. 相似文献
20.
Rowena Spence Robert J. Wootton Iain Barber Mirosław Przybylski Carl Smith 《Ecology and evolution》2013,3(6):1717-1726
The central assumption of evolutionary theory is that natural selection drives the adaptation of populations to local environmental conditions, resulting in the evolution of adaptive phenotypes. The three‐spined stickleback (Gasterosteus aculeatus) displays remarkable phenotypic variation, offering an unusually tractable model for understanding the ecological mechanisms underpinning adaptive evolutionary change. Using populations on North Uist, Scotland we investigated the role of predation pressure and calcium limitation on the adaptive evolution of stickleback morphology and behavior. Dissolved calcium was a significant predictor of plate and spine morph, while predator abundance was not. Stickleback latency to emerge from a refuge varied with morph, with populations with highly reduced plates and spines and high predation risk less bold. Our findings support strong directional selection in three‐spined stickleback evolution, driven by multiple selective agents. 相似文献