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At least 19 recordsLinked to original sources
PubMed1975

Investigation on Huntington's disease in the Canadian Prairies. II. Fecundity and fitness.

The reproductive performance of 157 patients with Huntington's disease, their 170 normal siblings and 150 matched unrelated controls is presented. Comparison with the general Canadian Prairie population in the appropriate age group is undertaken. Patients with Huntington's disease are not only more fecund than their unaffected sibs but also out-reproduce unrelated normal controls and members of the general population of corresponding age. Their fitness is thus estimated to be 1.14. Should the present reproductive pattern continue, the allele for Huntington's disease will double its frequency with consequent doubling of the prevalence of the disorder in six generations or approximately 150 years' time.

Female↗
PubMed1975

[Nutritional needs of adult Drosophila: influence of lecithins and of choline chloride on the fecundity, the fertility and the size of ova].

The lecithin or choline chloride deficiency, in Drosophila, results in an important decrease of the number of eggs produced, hatching and egg size. However, the ovogenesis is not completely stopped, even after 15 days. This effects seem caused by the choline deficiency. When used under the chloride form, choline has no toxic effect even at a rate as high as 3 g/litre. However, the lecithin has toxic effects for amounts up to 4 g/litre. In the adults, the optimal concentration could be about 2 g/litre for the lecithin and 300 mg/litre for the cholin chloride.

Animals↗
PubMed1977

[Magnesium in animal and human reproduction].

The literature concerned with the amount of magnesium in genital organs and products of sexual activity is analysed in the first chapter; these data are compared with those concerning other organs and replaced in a comprehensive view of the body, related or not with the medium. It is likely that magnesium plays a role in ovule maturation, sperm viability and fecundation in Invertebrates and Fishes. In Birds and Mammals, it appears to be necessary for fecundation. In the Discoglossus (Anurian Amphibian), the deficiency and the excess in Mg2+ reduce development and influence the growth of the body and the ovary. In the Rat, the pregnancy cannot be normal, unless the food contains an adequate supply of magnesium. Severe or mild deficiencies affect the site of fetal implantation and, if they are prolonged, lead to abortion in the first instance and pathological disorders in the latter. An ionic determination of sex has been established in various animal species and in Man. In some marine Invertebrates, and in the Discoglossus, changes in ionic concentration of the breeding medium carried out immediately after fecundation induce, at will, a majority of one sex or the other; in various Mammals and in Man, variations in the composition of mineral food administered to the female before fecundation may also induce changes in the sex ratio of the progeny.

Animals↗
PubMed2026

A horizontally transferred bacterial gene for pantothenic acid biosynthesis regulates diapause and reproduction in the spider mite Amphitetranychus viennensis.

Horizontal gene transfer (HGT) has contributed substantially to the evolution of arthropod genomes, yet the functional significance of many horizontally acquired genes remains poorly understood. The hawthorn spider mite, Amphitetranychus viennensis, is a devastating agricultural pest whose high fecundity and overwintering diapause afford its exceptional ecological resilience. Through a genome-wide screen, we identified 37 high-confidence horizontally transferred genes (HTGs) in A. viennensis. Among these candidates, we prioritized AvPBL, a gene encoding pantothenate-β-alanine ligase, for functional characterization because it controls the rate-limiting step of a distinctly non-metazoan pantothenic acid (vitamin B5) biosynthesis pathway. RNAi-mediated suppression of AvPBL significantly reduced transcript abundance and endogenous pantothenic acid levels, triggering a 23.7% reduction in cumulative fecundity and severely compromising the mites' ability to enter winter diapause. Importantly, exogenous pantothenic acid supplementation rescued these reproductive and diapause defects, directly linking the observed phenotypes to the disruption of pantothenic acid biosynthesis. Our results demonstrate that the horizontally transferred bacterial gene AvPBL has been functionally integrated into the endogenous metabolic network of A. viennensis, playing a critical role in vitamin B5 biosynthesis, reproduction, and diapause regulation. These findings provide direct evidence that horizontally acquired metabolic genes can shape key life-history traits and drive adaptive evolution in arthropods.

Amphitetranychus viennensis↗
PubMed2026

Maternal and developmental temperature modulate adult response to temperature in Drosophila melanogaster.

Beyond inherited genes and environmentally induced changes in gene expression, phenotypes can also be shaped by parental effects-an effect from a parental phenotype that causes modifications in offspring traits, which cannot be solely explained by the parental or offspring genomes. Such effects may prepare offspring for future environmental conditions and contribute to phenotypic plasticity, including responses to temperature. While temperature-induced plasticity has been extensively studied, the relative contributions of parental versus direct environmental cues remain poorly understood. The fruit fly Drosophila melanogaster is a powerful model for studying physiological and behavioral adaptation to temperature. Flies inhabit environments spanning broad thermal ranges and show evidence of parental effects, such as increased heat tolerance in offspring from warm-reared parents. Here, we exposed mothers to two experimental temperatures and split their broods between the same two temperatures to estimate the relative importance of maternal and developmental effects on adult physiological and developmental responses to temperature. We find that the reaction norms of locomotor activity under gradually increasing temperatures, responses to heat-shock and cold-shock, and fecundity are mostly governed by direct plastic responses to developmental environment. We detected comparatively weak maternal effects in the response to heat-shock, fecundity, and grand-offspring survival where matched environments counteracted the effects of direct offspring experience. We conclude that thermal experience during development is the primary determinant of phenotypic plasticity in D. melanogaster, while maternal experience contributes a small but non-negligible component.

Animals↗
PubMed1979

Theory of the dependence of population levels on environmental history for semelparous species with short reproductive seasons.

A population that is strongly self-regulating through density-dependent effects is expected to be such that, if many generations have elapsed since its establishment, its present size should not be sensitive to its initial size but should instead be determined by the history of the variables that describe the influence of the environment on fecundity, mortality, and dispersal. Here we discuss the dependence of abundance on environmental history for a semelparous population in which reproduction is synchronous. It is assumed that at each instant t: (i) the rate of loss of members of age a by mortality and dispersal is given by a function rho of t, a, and the present number x = x(a,t) of such members; and (ii) the number x(0,t) of members born in the population is given by a function F of t and the number of x(a(f),t) at a specified age a(f) of fecundity. It is further assumed that the functions rho and F have the forms rho(x,a,t) = pi(1)(a,t)x + pi(2)(a,t)x(2) and F(x(a(f),t),t) = nu(t)x(a(f),t). For such a population, a change in the environment is significant only if it results in a change in nu(t) pi(1)(a,t), or pi(2)(a,t), and, hence, the history of the environment up to time t is described by giving nu(tau), pi(1)(a,tau), and pi(2)(a,tau) for each tau </= t and all a in [0, a(f)]. We show that the dependence of x on the history of the environment can be calculated explicitly and has certain properties of "fading memory"; i.e., environmental events that occurred in the remote past have less effect upon the present abundance than comparable events in the recent past.

Animals↗
PubMedDate not supplied

[Effect of microsporidiosis on the fertility of Aedes caspius caspius (Culicidae) mosquitoes].

Effect of microsporidiosis on the fecundity of hosts A. c. caspius was studied. The calculation of eggs in hatches has shown that females developing from infected eggs lay 2--3 times lesser eggs than non-infected ones. Besides, the number of females laying eggs decreases considerably. Despite the females of mosquitoes suck blood before each egglaying the disease, which proceeds at their larval stage, affects greatly their fecundity. Additional feeding of females cannot compensate completely the disturbances caused by microsporidiosis.

Aedes↗
PubMed1979

T and B cells in the transfer of immunity against Trichinella spiralis in mice.

Enriched populations of T or B cells, prepared by nylon wool filtration of mesenteric node lymphocytes from mice infected with Trichinella spiralis, were capable of transferring immunity to normal and irradiated syngeneic mice. In cell recipients there was an early loss of fecundity by the worms and an accelerated expulsion from the intestine. Treatment with anti-Thy 1.2 serum, to deplete contaminating T cells, severely reduced or abolished the protective activity of enriched B-cell fractions. Replacement of contaminating T cells by normal T cells restored the capacity of B-cell fractions to reduce worm fecundity but did not result in worm expulsion. As it was shown that comparatively small numbers of T cells (3 x 10(6)) alone were effective in transferring immunity to irradiated mice it is suggested that the T cells act not as helper cells, but are involved in the generation of changes in the intestinal environment that are detrimental to worm survival.

Animals↗
PubMed1979

Cost-effectiveness evaluation of a home visiting triage program for family planning in Turkey.

Graduate Turkish midwives were trained in triage rules for determining family planning home visit frequency based on risk of couples. In a sample of 542 couples followed for six months, modern contraceptive use increased 22 per cent among high-risk and about 15 per cent among moderate- and low-risk couples. After making assumptions about the fecundity, contraceptive success, and pregnancy complications, the estimated average cost per complication averted was $61 for high-risk, $177 for moderate-risk and $526 for low-risk couples.

Adolescent↗
PubMed1978

Genetic and evolutionary fitness.

The advantages and disadvantages of evolutionary fitness (probability that a single mutant line will not become extinct) and genetic fitness (mean fecundity) are compared. For deterministic processes the two are equivalent, but for stochastic branching processes they may be totally unrelated except that an absolute genetic fitness of unity or less implies an evolutionary fitness of zero. To know the variance as well as the mean family size does not in general uniquely determine the evolutionary fitness. Except where genetic fitness is close to unity, the impact of selection is shown to be rapid for the binomial, Poisson, negative binomial, and truncated negative binomial distributions. Evolutionary fitness, though somewhat cumbersome, has greater relevance to evolution, genetic counseling, and voluntary population control; but genetic fitness which is much easier to handle is the more appropriate measure where a large number of mutants is involved. Some empirical data on the transmission of various types of characters from parent to child are analyzed to allow comparison of genetic fitness, Crow's index, and a Malthusian parameter, with evolutionary fitness. There is a fair, but far from perfect, agreement among them. Multiple correlation of evolutionary fitness with mean and variance of family size taken jointly suggests a much more satisfactory approximation. It thus appears that, at the least, the population geneticist cannot afford to ignore the variance (which is not adequately represented in Crow's index). These relationships, based on two sets of data only may be accidental and should be invoked with caution. It seems more than likely that other aspects of the distribution of family size (eg, even higher moments) may contain relevant information in certain cases.

Biological Evolution↗
PubMed2026

Transcriptomic insights into thermal stress reveal physiological trade-off between thermal stress adaptation and reproductive investment in Spodoptera litura.

Spodoptera litura, a highly polyphagous lepidopteran pest, poses a major threat to agricultural productivity due to its remarkable adaptability to diverse environmental conditions. Although heat stress is known to trigger transcriptional reprogramming in insects, the molecular mechanisms underlying thermal stress responses in S. litura remain poorly understood. In the present study, fourth-instar larvae were exposed to acute heat stress (44&#xa0;&#xb0;C) and compared with control conditions (27&#xa0;&#xb1;&#xa0;1&#xa0;&#xb0;C) to investigate heat-induced transcriptional alterations affecting physiology and reproduction. High-quality RNA-Seq data achieved more than 80% mapping efficiency, with a total of 15,782 transcripts were identified. Transcriptome analysis of S. litura larvae showed 323 differentially expressed genes (DEGs), of which 262 genes were significantly upregulated and 61 were downregulated in heat-stressed larvae compared to the control group. The DEGs were associated with stress response, reproduction, signalling, proteostasis, detoxification, oxidative stress, metabolism, development, and chromatin regulation. Heat shock proteins genes, including HSP70, HSP90, and HSP27, together with co-chaperones such as TRET-1, STIP1, and Starvin, were strongly upregulated, indicating enhanced cellular protection against protein damage and oxidative stress under heat stress. Conversely, key reproductive and cell cycle-related genes, including BARR, CAPD2, FEO, CDK2 and MORULA, were significantly downregulated, suggesting reproductive impairment and developmental arrest. RT-qPCR validation corroborated the RNA-Seq findings, demonstrating a heat-induced physiological trade-off that prioritizes survival over reproduction. Consistent with these molecular responses, heat-stressed insects exhibited marked reproductive impairment, including significant reductions in gonadosomatic index, eupyrene sperm bundle count, mating frequency, mating success, female calling behaviour, copulation duration, fecundity, and egg fertility. Collectively, these findings provide comprehensive insights into the molecular basis of thermal adaptation in S. litura and demonstrate that acute heat stress compromises reproductive fitness while activating conserved stress-response pathways that promote short-term survival.

Animals↗