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PubMed1996

Arylsulphatase A activity and sulphatide concentration in the female rabbit oviduct are under physiological hormonal influence.

Oviduct samples of female rabbits in different phases of the reproductive cycle were analysed to establish the role of sex steroid hormones in the regulation of sulphatide concentration and arylsulphatase A activity. In addition to biochemical procedures, histochemical techniques were used to localize both enzyme activity and the natural substrate. The plasma concentrations of progesterone and 17 beta-oestradiol were determined by radioimmunoassay (RIA). The findings show that the parameters examined undergo considerable changes during the different phases of the reproductive cycle. Oestrogens exert an inducing action on arylsulphatase A activity, while progesterone inhibits it. Fluctuations of the catabolic arylsulphatase activity condition the sulphatide concentration, which reaches maximum values at the eighth post-ovulatory day when progesterone dominance is consolidated. In this phase of the reproductive cycle, thin-layer chromatography confirms the presence not only of larger quantities of sulphatides, but also of all other lipid fractions.

Animals↗

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 18). Comparative 4 and 2 weeks oral repeated dosing studies on male reproductive organs in rats treated with 5-fluorouracil.

Oral repeated toxicity studies were conducted to compare the effects of 5-fluorouracil (5-FU) administered for 4 or 2 weeks on male reproductive organs of Sprague-Dawley (SD) rats. In both studies, decrease of feces, abnormal fur and emaciation were observed. On gross autopsy examination, softening/atrophy of the testis as well as atrophy of accessory reproductive organs were noted, and absolute organ weights of male reproductive organs were almost all reduced in both studies. Histopathologically, degeneration of the seminiferous epithelium in the testis and desquamated cell debris in the epididymal ducts were apparent after both time periods. In the 2-week study, furthermore, exfoliation of the seminiferous epithelium, formation of multinucleated giant cells and vacuolation of Sertoli cells in the seminiferous tubules in the testis, and decrease of sperms in the epididymal ducts were observed. The present results indicated that a 2-week study is sufficient to detect effects on the male reproductive organs of 5-FU treatment. In our study, however, changes in associated parameters after 2-week treatment of 8-week-old rats were greater than those after 4 weeks in 6-week-old rats. Thus, for detection of 5-FU-induced male reproductive toxicity, we can evaluate more accurately by using maturated rats of the same age.

Animals↗

PubMed2003

Human reproduction: a comparative background for medical hypotheses.

Successful reconstruction of any aspect of human evolution requires broad-based comparisons with other primates and other eutherian mammals. If quantitative data are involved, the scaling influence of body size must be taken into account, and bivariate allometric analysis is a very useful tool. Broad-based comparisons lead to recognition of general principles that can feed into hypotheses concerning human reproductive medicine. Here, this approach is applied to basic life-history parameters (age at sexual maturity, gestation period, litter size, lactation period, interbirth interval, maximum lifespan), testicular dimensions and male mating strategies, female ovarian processes and mating cycles, placentation and embryonic/fetal development, gestation periods and neonatal condition, and brain development in relation to reproduction. Comparisons reveal that some features claimed to be unique to human beings in fact occur more widely in primates, such as 'loss of oestrus', which probably evolved in the common ancestor of higher primates (monkeys, apes and humans). Although humans show an extreme condition, in most higher primates mating is not strictly confined to the periovulatory period. Because this condition introduces the danger of fertilization with ageing gametes, it must have been favoured by strong selection and accompanied by the evolution of compensatory mechanisms. Overall, it seems likely that the high incidence of pre-eclampsia in human pregnancies is attributable to a partial failure of compensatory mechanisms associated with highly invasive placentation.

Adaptation, Physiological↗

PubMed2002

Combined ab initio/empirical approach for optimization of Lennard-Jones parameters for polar-neutral compounds.

The study of small functionalized organic molecules in aqueous solution is a useful step toward gaining a basic understanding of the behavior of biomolecular systems in their native aqueous environment. Interest in studying amines and fluorine-substituted compounds has risen from their intrinsic physicochemical properties and their prevalence in biological and pharmaceutical compounds. In the present study, a previously developed approach which optimizes Lennard-Jones (LJ) parameters via the use of rare gas atoms combined with the reproduction of experimental condensed phase properties was extended to polar-neutral compounds. Compounds studied included four amines (ammonia, methylamine, dimethylamine, and trimethylamine) and three fluoroethanes (1-fluoroethane, 1,1-difluoroethane, and 1,1,1-trifluoroethane). The resulting force field yielded heats of vaporization and molecular volumes in excellent agreement with the experiment, with average differences less than 1%. The current amine CHARMM parameters successfully reproduced experimental aqueous solvation data where methylamine is more hydrophilic than ammonia, with hydrophobicity increasing with additional methylation on the nitrogen. For both the amines and fluoroethanes the parabolic relationship of the extent of methylation or fluorination, respectively, to the heats of vaporization were reproduced by the new parameters. The present results are also discussed with respect to the impact of parameterization approach to molecular details obtained from computer simulations and to the unique biological properties of fluorine in pharmaceutical compounds.

Amines↗

PubMed2001

Interrelationships between seminal parameters and sperm nuclear DNA damage before and after density gradient centrifugation: implications for assisted conception.

BACKGROUND: With an increase in the use of assisted reproduction technologies the requirements of the diagnostic semen analysis are constantly changing. METHODS: Spermatozoa from patients undergoing IVF were analysed by examining the conventional semen parameters and DNA/chromatin integrity, using in-situ nick translation (NT) and the Chromomycin A(3) fluorochrome, which indirectly demonstrates a decreased presence of protamine. Samples were examined before and after preparation using discontinuous density gradient centrifugation. RESULTS: Density gradient centrifugation enriched samples by improving the percentage of morphologically normal forms by 138% and sperm nuclear integrity by 450%. Sperm nuclear integrity as assessed by in-situ nick translation (NT) demonstrated a very clear relationship with sperm concentration, motility and morphology. Morphology correlated with fertilization rates of patients undergoing IVF, while NT values of the spermatozoa post-preparation were significantly lower in pregnant patients. CONCLUSIONS: We have demonstrated that along with the classical semen parameters, the assessment of nuclear integrity improves the characterization of the semen sample and may be used as a tool for allocating patients to specific assisted reproduction treatments.

Adult↗

PubMed2001

Mass production of entomopathogenic nematodes for plant protection.

Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are commercially used to control pest insects. They are symbiotically associated with bacteria of the genera Photorhabdus and Xenorhabdus, respectively, which are the major food source for the nematodes. The biology of the nematode-bacterium complex is described, a historical review of the development of in vitro cultivation techniques is given and the current use in agriculture is summarised. Cultures of the complex are pre-incubated with the symbiotic bacteria before the nematodes are inoculated. Whereas the inoculum preparation and preservation of bacterial stocks follow standard rules, nematodes need special treatment. Media development is mainly directed towards cost reduction, as the bacteria are able to metabolise a variety of protein sources to provide optimal conditions for nematode reproduction. The process technology is described, discussing the influence of bioreactor design and process parameters required to obtain high nematode yields. As two organisms are grown in one vessel and one of them is a multicellular organism, the population dynamics and symbiotic interactions need to be understood in order to improve process management. Major problems can originate from the delayed or slow development of the nematode inoculum and from phase variants of the symbiotic bacteria that have negative effects on nematode development and reproduction. Recent scientific progress has helped to understand the biological and technical parameters that influence the process, thus enabling transfer to an industrial scale. As a consequence, costs for nematode-based products could be significantly reduced.

Animals↗

PubMed2001

Variable timing of reproduction in unpredictable environments: adaption of flood plain plants.

We study the evolutionarily stable reproductive timing of annual plants that face unpredictable environmental disturbances. Plants living in a riverbed often experience a disturbance before they reproduce, suffering major fitness loss. Plants reproducing prior to the flood season are free from the risk of lost reproduction, but a small flowering plant can produce only a few numbers of seeds. If the date of disturbance is unpredictable, a mixed strategy of reproductive timing may evolve in which individuals of the same genotype have different reproductive dates. We calculate the evolutionarily stable phenotype distribution analytically. Depending on parameters, the ESS distribution is either (1) a timid strategy-the plant reproduces when small, prior to the major disturbance season; (2) a bold strategy-the plant reproduces only when it is fully grown; (3) a mixture of early and late reproduction; or (4) dates of reproduction spread over a wide interval. We also examine the effects of developmental and environmental noises that make realized flowering dates deviate from that programmed by the genotype, which follows the ESS distribution. In the presence of noise, the ESS distribution of programmed timing of reproduction is discrete.

Climate↗

PubMed2001

Estrogen as modulator of genes expression involved in control of reproduction.

The hypothalamic neurons, pituitary and their target cells, as genetically programmed to respond specifically to gonadal steroids (GS) and seasonal photoperiodic stimuli, play a crucial role in regulation of target genes transcription and regulatory ligands are conserved throughout evolution. Memory of these cells, acquired through the advanced evolution and programmed genes expression, may be modulated, transitory or permanently, by GS and estrogen (E) is a key hormone of these steroids. Pituitary chromophobes (Chr) and prolactin (PRL) cells reactions of birds and rats to GS and seasonal photoperiod were used as a parameter for elucidation of hypothalamic neurons and regulation of the animals reproduction. As a result of proliferative rate of chromophobes and hypertrophy of PRL cells, pituitary gonadotropic hormone (GTH) cells differentiation and activities are decreased, retarded or even inhibited and vice versa. The inverse relationship between PRL and GTH play a crucial role in regulation of reproduction. Light absorbed by rodopsin in the photoreceptor cells are transmitted via specific hypothalamic neurons to pars tuberalis cells, which are sensitive to photoperiodic stimuli and neurohormones as regulators of PRL cells activities.

Animals↗

PubMed2005

Sperm survival and heterogeneity are correlated with fertility after intrauterine insemination in superovulated ewes.

Efficient animal production involves accurate estimations of fertilizing ability. One key factor is the plasma membrane of the sperm cell, which is actively involved in the cascade of events before oocyte fusion. Many methods are used to analyze the characteristics of this membrane, including partition in aqueous two-phase systems which is an efficient method to analyze sperm surface changes accounting for loss of viability and different functional states. Centrifugal countercurrent distribution (CCCD) analysis can also be used in an aqueous two-phase system to determine the relationship between sperm parameters and in vivo fertility in ewes. In a previous work, we found a significant correlation between two post-CCCD parameters (heterogeneity and recovered viability) and field fertility when the same sample was used after cervical AI. The present study was intended to find out whether the control of several external factors that affect reproductive efficiency is able to increase the correlation coefficient between post-CCCD parameters and fertility. Thus, 90 Rasa aragonesa ewes were controlled on the same farm and received intrauterine inseminations using the same technical equipment. The fertilizing ability of the raw semen and sperm samples selected by a dextran/swim-up process was compared using a low number of spermatozoa per insemination (7 x 10(7)) to enhance possible fertility differences. A new post-CCCD parameter was considered; the loss of viability (LV) occurred during the CCCD process. This variable denotes the sperm surviving ability and corresponds to the difference between the total number of viable cells loaded and recovered after the CCCD run. The mean fertility of eight sperm control samples was 60% (range: 25-76%), and there was no significant correlation between standard parameters and in vivo fertility. LV ranged from 2 to 69% (average 27%) and was negatively correlated with fertility (r = -0.914, P < 0.01). Ejaculate heterogeneity (H) ranged from 20 to 47% and was positively, but not significantly, correlated with fertility (r = 0.391). A predictive equation for fertility was deduced by multiple analysis with a very high correlation coefficient (r = 0.967), and level of significance (P < 0.005): predictive fertility PF = 52.546 - 0.594 LV + 0.665 H. The mean fertility of 13 swim-up selected samples was 63% (range: 25-86%). Again, only parameters derived from the CCCD analysis were highly correlated with fertility, especially LV and H (P < 0.05).

Animals↗

PubMed2002

Chronic neuropeptide Y Y5 receptor stimulation suppresses reproduction in virgin female and lactating rats.

Continuous infusion of neuropeptide Y (NPY) disrupts cyclicity and delays the onset of puberty in female rats indicating that NPY can suppress reproduction. Central application of NPY also reliably increases food intake in rats. States with heavy demands on energy resources where reproduction is also inhibited, such as lactation, are similarly accompanied by elevations in central NPY expression. In previous studies, we have shown that, compared to lactating rats fed ad libitum, food-restricted lactating rats exhibit a longer period of lactational diestrus that is correlated with increased central NPY expression. These studies link NPY to the inhibition of reproduction that is mediated by low availability of energy resources. Here, we examine the effect of chronic 7-day infusion of the mixed Y1/Y4/Y5 agonist (Leu31, Pro34) NPY and selective agonists to the Y2 (NPY13-36) and Y5 (D-Trp32 NPY and D-Trp34 NPY) receptors on food intake and the oestrous cycle of virgin female rats. We also investigated the effect of chronic infusion from day 8-15 postpartum (pp) of D-Trp32 NPY and D-Trp34 NPY on food-intake and the length of lactational diestrus in lactating rats fed ad libitum. In virgin females, infusion of (Leu31, Pro34) NPY and both the Y5 agonists lengthened the period between consecutive oestrus days while the Y2 agonist NPY13-36 was without effect. Selective Y5 receptor activation alone caused an increase in food intake in virgin females. In lactating females, D-Trp32 NPY extended the length of lactational diestrus, while D-Trp34 NPY had no effect on this parameter. These data suggest that Y5 receptor activation suppresses the reproductive axis in both virgin and lactating rats and that Y5 receptor activation enhances food-intake in virgin females.

Animals↗

PubMed1992

Reproductive and developmental toxicity studies of a linear alkylbenzene mixture in rats.

Alkylate 215, a mixture of linear decyl- to tridecylbenzenes, is an intermediate in the manufacture of detergent sulfonates. A two-generation reproduction study and a developmental toxicity study were conducted using single daily doses given by gastric intubation in a corn oil vehicle. In the reproduction study, groups of 30 rats/sex/group were given doses of 0, 5, 50, or 500 mg/kg/day. F0 animals received a 10-week premating treatment period and were then mated to produce a single litter; F1 adults were selected from the F1 litters. F1 animals were dosed for 11 weeks before mating to produce a single litter. Adults and weaned pups received a gross postmortem examination. Histopathology studies were conducted on reproductive tissues, tissues with gross lesions, and the pituitary gland taken from each adult in the control and high dose groups. In the developmental toxicity study, groups of 24 mated female rats were given 0, 125, 500, or 2000 mg/kg/day on Days 6 through 15 of gestation. Dams were terminated on gestation Day 20 and fetuses were examined for external, soft tissue, and skeletal defects. Results of the reproduction study were as follows. At 50 mg/kg/day, pup weights were decreased at Day 7 in the F1 litter. At 500 mg/kg/day, decreases were found in the F0 females in premating and early lactation weight gains; in both generations in premating weight gains in males and in weight gains during gestation in females; and in litter size, pup viability at birth, Day 0-4 survival, and pup weights on Days 14 and 21. The NOAEL for reproductive effects was 5 mg/kg/day. The developmental toxicity study found effects on several parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Reproductive effects of dietary soy in female Wistar rats.

This study was designed to assess the effects of administration of dietary soy on reproductive function and fertility of female Wistar rats. Four groups, each of 20 females, were used. Control animals were fed a standard cereal-based diet for rats. Treated animals were fed a standard diet supplemented with 0.7%, 1.2% or 2.4% of a soy extract. Treatment started at weaning and continued until day 7 post-partum (day of sacrifice). Growth depression was seen in the 2.4% soy group. Vaginal opening occurred earlier in females receiving soy supplemented feed when compared with controls. Analysis of vaginal smears revealed that all animals were cycling, although an increase in the mean duration of each cycle was seen in the 2.4% soy group. Uterine effects were observed in high-dose females and included increases in weight, oedema, endothelial hyperplasia and leucocytic infiltration. Vaginal modifications (i.e. inflammation, hyperkeratosis and dyskeratosis) and alterations in the distribution of follicular size in the ovaries were also observed among treated animals. These data suggest that long-term exposure to high doses of phytoestrogens can produce significant agonistic actions in several oestrogen-dependent tissues and parameters, even though in this model no clear influence on reproductive processes was observed.

Animals↗

PubMed1983

Seasonal changes in open-field behavior in wild male meadow voles (Microtus pennsylvanicus).

Open-field behavior of free-living meadow voles was measured in males held overnight in the laboratory. Movement variables were positively correlated, and had negative associations with grooming and freezing. Parameters including activity, freezing, urinating, and grooming showed annual fluctuations related to the reproductive season. Together with the results of a previous study showing castration of wild voles results in altered open-field behavior, these results emphasize the role of testicular hormones in influencing this behavior. Factor analysis identified an activity component accounting for 39% of the variation, but other parameters were little simplified by this procedure. Most factors cycled annually, and significant variation was found in all eight factors during the 4-year sample. Open-field behavior varied between different reproductive and age segments of the population, and may be related to population processes such as dispersal.

Aggression↗

PubMed2001

Providing toxicokinetic support for reproductive toxicology studies in pharmaceutical development.

A package of toxicokinetic and disposition studies is generally conducted in support of reproductive toxicology studies in the development of new drugs. The content of the package often varies between companies and sometimes either insufficient data or inappropriate/over-interpreted data are presented. This paper was written to aid investigators in the design of toxicokinetic and disposition studies in support of reproductive toxicology. It offers: (1) an overview on the regulatory guidelines for toxicokinetics, (2) methods for the derivation of toxicokinetic parameters, (3) suggestions on general toxicokinetic study design, (4) suggestions on the specific design of toxicokinetic support for reproductive toxicology studies, and (5) an overview of species differences in placental transfer and the applicability (or otherwise) of transfer studies in drug development. Toxicokinetic and drug disposition studies should be carefully designed in order to gather relevant information, and consideration should be given to the usefulness of any data before embarking on a series of supporting or routine experiments.

Animals↗

PubMed2005

It's good to be queen: classically eusocial colony structure and low worker fitness in an obligately social sweat bee.

Lasioglossum malachurum, a bee species common across much of Europe, is obligately eusocial across its range but exhibits clear geographic variation in demography and social behaviour. This variation suggests that social interactions between queens and workers, opportunities for worker oviposition, and patterns of relatedness among nest mates may vary considerably, both within and among regions. In this study, we used three microsatellite loci with 12-18 alleles each to examine the sociogenetic structure of colonies from a population at Agios Nikolaos Monemvasias in southern Greece. These analyses reveal that the majority of colonies exhibit classical eusocial colony structure in which a single queen mated to a single male monopolizes oviposition. Nevertheless, we also detect low rates of multiqueen nest founding, occasional caste switching by worker-destined females, and worker oviposition of both gyne and male-producing eggs in the final brood. Previous evidence that the majority of workers show some ovarian development and a minority (17%) have at least one large oocyte contrasts with the observation that only 2-3% of gynes and males (the so-called reproductive brood) are produced by workers. An evaluation of the parameters of Hamilton's Rule suggests that queens benefit greatly from the help provided by workers but that workers achieve greater fitness by provisioning and laying their own eggs rather than by tending to the queen's eggs. This conflict of interest between the queen and her workers suggests that the discrepancy between potential and achieved worker oviposition is due to queen interference. Comparison of relatedness and maternity patterns in the Agios Nikolaos Monemvasias population with those from a northern population near Tübingen, Germany, points to a north-south cline of increasingly effective queen control of worker behaviour.

Animals↗

PubMed2002

The impact of testicular and accessory sex gland function on sperm chromatin integrity as assessed by the sperm chromatin structure assay (SCSA).

BACKGROUND: The sperm chromatin structure assay (SCSA) provides an objective assessment of sperm chromatin integrity, which is essential for normal sperm function. SCSA is valuable as a fertility marker in epidemiological studies and in the clinical situation. Little is known about the impact of testicular and post-testicular function on SCSA parameters. METHODS: Ejaculates from 278 military conscripts of median age 18.1 (range 18-21) years were included. Levels of reproductive hormones, the length of the CAG repeat of the androgen receptor gene, sperm concentration, abstinence period and biochemical parameters of epididymal and accessory sex gland secretions were correlated to the SCSA parameters, DNA fragmentation index (DFI) and highly DNA stainable (HDS) cells. RESULTS: Negative correlations were found between sperm concentration and DFI (r = -0.119, P = 0.049) and HDS (r = -0.513, P < 0.0001). DFI was negatively correlated with levels of estradiol (r = -0.19, P = 0.002) and free testosterone (r = -0.13, P = 0.03). DFI also correlated positively with abstinence time (r = 0.17, P = 0.005), and with seminal concentrations of fructose (r = 0.18, P = 0.004) and zinc (r = 0.12, P = 0.04). CONCLUSIONS: Sex steroid production, spermatogenic function, abstinence time and seminal vesicle function appear to impact on sperm chromatin integrity and thereby on sperm fertilizing capacity. These findings may improve present understanding of the pathophysiology of male infertility.

Adolescent↗

PubMed1994

[Functional state of the reproductive system in patients with the hypogonadotropic form of amenorrhea during use of various protocols of ovulation induction with human menopausal gonadotropins].

Clinico-hormonal parameters of cycles stimulated with human menopausal gonadotropins in patients with hypogonadotropic amenorrhea and of spontaneous cycles in healthy women of reproductive age are compared. Estradiol hypersecretion in both phases of induced cycle was revealed: hydrocortisone in phase 1 and progesterone and testosterone in phase 2. Dexamethasone in daily dose 0.25 mg was administered for correction. This resulted in a noticeable reduction of estradiol hyperproduction in the first phase of stimulated cycles and in hyperandrogenism elimination. Folliculogenesis, ovulation, and early embryogenesis conditions in schemes of induction with human menopausal gonadotropins and dexamethasone therapy were close to physiologic ones, this resulting in increased share of fertile cycles.

Adult↗

PubMed2005

F-statistics under alternation of sexual and asexual reproduction: a model and data from schistosomes (platyhelminth parasites).

Accurate inferences on population genetics data require a sound underlying theoretical null model. Nearly nothing is known about the gene dynamics of organisms with complex life cycles precluding any biological interpretation of population genetics parameters. In this article, we used an infinite island model to derive the expectations of those parameters for the life cycle of a dioecious organism obligatorily alternating sexual and asexual reproductions as it is the case for schistosomes (plathyhelminth parasites). This model allowed us to investigate the effects of the degree of mixing among individuals coming from different subpopulations at each new generation (represented in the model by the migration rates before and after clonal reproductions) and the variance in the reproductive success of individuals during the clonal phase. We also consider the effects of different migration rates and degrees of clonal reproductive skew between male and female individuals. Results show that the variance in the reproductive success of clones is very important in shaping the distribution of the genetic variability both within and among subpopulations. Thus, higher variance in the reproductive success of clones generates heterozygous excesses within subpopulations and also increases genetic differentiation between them. Migration occurring before and after asexual reproduction has different effects on the patterns of F(IS) and F(ST). When males and females display different degrees of reproductive skew or migration rates, we observe differences in their respective population genetic structure. While results of the model apply to any organism alternating sexual and clonal reproductions (e.g. all parasitic trematodes, many plants, and all aphididae), we finally confront some of these theoretical expectations to empirical data from Schistosoma mansoni infecting Rattus rattus in Guadeloupe.

Animals↗