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PubMed2003

Serum relaxin concentrations and reproduction in male bonnethead sharks, Sphyrna tiburo.

Relaxin is a 6-kd polypeptide hormone that is responsible for regulating several reproductive processes in female vertebrates, but its role in male reproduction remains unclear. To aid in clarifying this role, the objective of the present study was to investigate changes in endogenous relaxin levels associated with reproductive events in male elasmobranchs, which represent one of only three vertebrate groups known to possess this hormone. Serum relaxin concentrations were measured in 27 immature and 66 mature male bonnethead sharks (Sphyrna tiburo), a species with a well-characterized, seasonal reproductive cycle. Temporal changes in serum relaxin concentrations of immature male S. tiburo were not observed. In contrast, a temporal cycle in serum relaxin concentrations of mature male S. tiburo was observed in individuals from two sampling locations. Significant increases (P<0.05) in serum relaxin concentrations of mature male S. tiburo from both collection sites occurred during late spermatogenesis and the mating period, two critical stages of the reproductive cycle. The results from this study suggest that relaxin may play an important role in regulating semen quality, or other aspects of reproduction in male sharks. This is the first study to demonstrate a temporal pattern in endogenous serum Rlx concentrations associated with reproductive events in feral vertebrates. As such, it strengthens earlier hypotheses that suggested a role for this hormone in regulating male vertebrate fertility and copulatory success.

Animals↗

PubMed1999

The emerging international policy agenda for reproductive health services in conflict settings.

Over the past 20 years, shifts in the nature of conflict and the sheer numbers of civilians affected have given rise to increasing concern about providing appropriate health services in unstable settings. Concurrently, international health policy attention has focused on sexual and reproductive health issues and finding effective methods of addressing them. This article reviews the background to the promotion and development of reproductive health services for conflict-affected populations. It employs qualitative methods to analyse the development of policy at international level. First we examine the extent to which reproductive health is on the policy agendas of organisations active in humanitarian contexts. We then discuss why and how this has come about, and whether the issue has sufficient support to ensure effective implementation. Our findings demonstrate that reproductive health is clearly on the agenda for agencies working in these settings, as measured by a range of established criteria including the amount of new resources being attracted to this area and the number of meetings and publications devoted to this issue. There are, however, barriers to the full and effective implementation of reproductive health services. These barriers include the hesitation of some field-workers to prioritise reproductive health and the number and diversity of the organisations involved in implementation. The reasons for these barriers are discussed in order to highlight areas for action before effective reproductive health service provision to these populations can be ensured.

Conflict of Interest↗

PubMed2001

The role of pheromones and biostimulation in animal reproduction.

It is now known that pheromonal communication plays an important role in mammalian behaviour and reproductive processes. Chemical communication with pheromones is one means of transmitting such information. In mammals, signalling and priming pheromones are thought to act either singly or in combination through olfaction, auditory, visual (sight) or tactile stimuli. Pheromones are air-borne chemical substances ("signals") released in the urine or feces of animals or secreted from cutaneous glands that are perceived by the olfactory system and that elicit both behavioural and endocrine responses in conspecifics. Extensive studies in insects, rodents, swine, sheep, goats and cattle have established the importance of pheromones in the strong influence exerted by the male on reproductive activity in the female. There is a pheromone produced by the queen honey bee, which has two functions: inhibition of queen rearing and suppression of oogenesis in workers and in addition attracts drones during nuptial flight. It has also been demonstrated that the urine of male mice, rats, feral species and other wild rodents contains a priming pheromone that is responsible for hastening puberty in the females. Pheromones in the wool, wax and urine of a ram are sufficient to stimulate ewes to ovulate, while the buck has a strong characteristic seasonal odor and a buck jar containing the odor of the buck can be used as an aid in the detection of oestrus in does. The mere presence of the boar at the time of insemination of the sow improves sperm transport and ovulation, while the presence of the vasectomised bull has been reported to hasten the onset of puberty in heifers and also early resumption of ovarian activity in cattle following parturition. The role of pheromones in bovine reproduction is not as clearly defined as in sheep, goats and swine. Pheromones and other allelomimetic cues can exert profound effects on reproductive activity via the hypothalamic system that generates pulses of gonadotropin-releasing hormone. Manipulations of these factors and other pathways linking environmental inputs to reproductive output can lead to developing the concept of "control systems technologies", aimed at controlling reproductive performance. The knowledge acquired on the effectiveness of biostimulation; the factor which conditions it and the biological mechanism which produces it in livestock species, allows its use as a breeding management tool. The understanding of the role of pheromones could be of potential economic importance in addressing some of the problems associated with livestock production in the tropics. The biostimulation technique offers a potentially useful and practical way to improve reproductive efficiency in livestock species in the tropics. The exact nature of the cues and the role of biostimulation in livestock species especially swine, sheep, goats and cattle in developing countries require more attention.

Animals↗

PubMed2001

Slow aging during insect reproductive diapause: why butterflies, grasshoppers and flies are like worms.

Diapause is a state of arrested development accompanied by physiology for somatic persistence. Diapause is common in many invertebrates and is familiar to biogerontology in the context of Caenorhabditis elegans dauer. Among insects, diapause may occur in embryos, larvae, pupae or adults. At the adult stage, reproductive diapause arrests development of oogenesis, vitellogenesis, accessory gland activity, and mating behavior. Reproductive diapause has been well studied in monarch butterflies, several grasshoppers, and several Diptera, including Drosophila and Phormia. In monarchs and in grasshoppers, reproductive diapause physiology has been experimentally induced by the surgical removal of the corpora allata, the source of adult juvenile hormone; allatectomy in each case was found to double adult longevity. Among Drosophila, the endemic D. triauraria of Japan, and D. littoralis of Finland over-winter as adults in reproductive diapause. How D. melanogaster winter is poorly understood, but reproductive diapause can be cued by cool temperature. In laboratory studies, the mortality rates of post-diapause D. melanogaster are similar to rates of newly enclosed, young flies. This implies that senescence during diapause is slow or negligible. Slow aging during the diapause period may involve elevated somatic stress resistance as well as reallocation of resources to somatic maintenance. Reproductive diapause in Drosophila is proximally controlled by down regulation of juvenile hormone, a phenotype that is also produced by mutants of the insulin-like receptor InR, homologue of C. elegans daf-2. We propose neuroendocrine control of reproductive diapause in D. melanogaster that includes phenotypic plasticity for rates of senescence.

Aging↗

PubMedDate not supplied

Reproductive effects in male and female rats from neonatal exposure to p-octylphenol.

A number of alkylphenolic compounds are used in a variety of commercial products and have been shown in in vitro studies to be weakly estrogenic, but in vivo data are not available addressing this issue in mammals. Human exposure to alkylphenols may occur not only from these environmental contaminants but also through contact with manufactured and metabolic breakdown products. In this study, Sprague-Dawley rats were exposed to octylphenol by oral gavage at doses of 0 (vehicle: corn oil), 12.5, 25, 50, or 100 mg/kg once daily on postnatal days 1 through 5 to examine its effects on male and female reproductive function after puberty. In addition, preputial separation and vaginal opening as endpoints of sexual maturation, estrous cycling, sperm count, serum testosterone concentration, and histopathologic changes of the reproductive organs of male and female rats were examined. Male reproductive organs were weighed at necropsy. Body weights of male and female rats exposed to octylphenol at 50 and 100 mg/kg throughout the study after the administration period, those of both sexes at 7 and 9 weeks of age in the 25 mg/kg group, and that of females at 9 weeks of age in the 12.5 mg/kg group were lower than those of controls. Significant delays in acquisition of puberty in males and females exposed to octylphenol at 50 and 100 mg/kg were observed. Estrous cycle, copulation and fertility, sperm count, and serum testosterone concentration were not affected by neonatal exposure to octylphenol. Significant decrease in absolute and relative prostate weight in the 12.5, 25, 50, and 100 mg/kg groups, and absolute epididymal weight in the 100 mg/kg group, increase in relative testes weight in the 100 mg/kg group, and relative seminal vesicle weights in the 50 and 100 mg/kg groups were found. Histopathologic analyses of reproductive organs in male and female rats exposed neonatally to octylphenol revealed no marked alterations. The results of this study indicate that early neonatal exposure to octylphenol by oral gavage did not cause dysfunction of reproductive performance (mating and fertility) in male or female rats, and no disruption of development of the reproductive tract was observed in male or female rats, while significant decreases in body weights in the 25 mg/kg and more groups, delays of sexual maturation in the 50 mg/kg and greater groups, and decrease in ventral prostate weights in all octylphenol-treated groups were found. Therefore, it is concluded that NOAEL (no-observed adverse effect level) for systemic toxicity was < or =12.5 mg/kg/day and that for reproductive toxicity was 100 mg/kg/day under the present experimental condition.

Administration, Oral↗

PubMedDate not supplied

Reproductive function in rats exposed neonatally to bisphenol A and estradiol benzoate.

The reproductive function in rats treated subcutaneously (s.c.) with 300 microg/g bisphenol A or 2 microg/g estradiol benzoate from postnatal Day 1 to 5 was examined after puberty as well as histolopathogic changes in reproductive organs. All male and female rats treated postnatally with estradiol benzoate showed poor reproductive capability, including adverse effects on masculine sexual behavior, and marked histopathologic alterations of the reproductive organs. In addition, estradiol benzoate markedly reduced the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in males. On the other hand, all male and female rats treated postnatally with bisphenol A showed normal reproductive function and no histopathologic abnormalities of reproductive organs. Bisphenol A did not affect the volume of the SDN-POA. These results indicated that neonatal exposure to estradiol benzoate affects reproductive function in male and female rats, and treatment with bisphenol A at a fairly high dose was ineffective if given postnatally to male and female rats.

Animals↗

PubMed2002

Short-changing reproductive health.

Health sector reformers, particularly the economists among them, are prone to reject calls for more financial support for reproductive health as "special pleading" even when the argument is made that reproductive health is a basic human right. Reproductive health is not alone in this. Up to now, however, the idea that the right to reproductive health care should take precedence over other health rights has not been put on the table. Economists ask how much interventions cost and whether there is enough money to cover all of the interventions being proposed; if not, they ask which interventions will be funded. Basing decisions about spending for health on evidence about the burden of disease is a way of using the principles of economics to improve health systems performance. However, this methodology poses some special problems for reproductive health as pregnancy is not a disease. Further, economic principles are not the only valid criteria for decisions about health care funding. Those who are concerned about reproductive health need to remain vigilant about the impact of these changes and counter with their own evidence on how they may or may not be contributing to improved health system performance and to reproductive health and rights.

Decision Making, Organizational↗

PubMed2003

HIV/AIDS in the shadows of reproductive health interventions.

In December 1999, the Tanzanian president declared HIV/AIDS a national disaster. By the time the National Policy on HIV/AIDS was released in 2001, an estimated 750,000 women of reproductive age were infected. Yet in spite of the impact of HIV on reproductive health, AIDS and reproductive health programmes are still thought of and implemented through separate channels, to the detriment of both. However, although AIDS remains in the shadows of reproductive health interventions, the lack of AIDS talk does not lessen the impact of the disease on people's lives. During the course of my participant observations in maternal and child health/family planning (MCH/FP) clinics collected during 25 months of fieldwork in 10 clinics in Morogoro, Ruvuma and Kilimanjaro Regions, I rarely heard about AIDS. This article attempts to analyse why. Historically competing bureaucracies in MCH/FP and gender and development are not easily unified with a vertical HIV/AIDS control programme under the umbrella of "reproductive health". HIV/AIDS cannot merely be inserted into existing family planning programmes, re-named "reproductive health" programmes. As the AIDS epidemic is transformed through new technologies, reproductive health policy and priorities will be called into question and force us to look at the state of the African health care system, networks of care-giving, and how individuals and communities fail when there is no socio-economic safety net.

Communicable Disease Control↗

PubMed2005

Women's perceptions of reproductive health in three communities around Beirut, Lebanon.

The aim of this study was to elicit definitions of the concept of reproductive health among women in three communities around Beirut, Lebanon, as part of the reproductive health component of a larger Urban Health Study. The communities were characterised by poverty, rural-urban mobility and heterogeneous refugee and migrant populations. A random sample of 1,869 women of reproductive age completed a questionnaire, of whom a sub-sample of 201 women were randomly selected. The women's understanding of good reproductive health included three major themes, which were expressed differently in the three communities. Their understanding included good physical and mental health, and underscored the need for activities promoting health. Their ability to reproduce and raise children, practise family planning and birth spacing, and go through pregnancy and motherhood safely were central to their reproductive duties and their social status. Finally, they saw reproductive health within the context of economic status, good marital relations and strength to cope with their lives. These findings point to the need to situate interventions in the life course of women, their health and that of their husbands and families; the importance of reproduction not only from a health services point of view, but also as regards women's roles and responsibilities within marriage and their families; and taking account of the harsh socio-economic conditions in their communities.

Adolescent↗

PubMed2005

Focus on women: linking HIV care and treatment with reproductive health services in the MTCT-Plus Initiative.

Despite important advances in expanding access to antiretroviral therapy in the countries most heavily affected by HIV/AIDS, there has been little consideration of the connections between HIV prevention, care and treatment programmes and reproductive health services. In this paper, we explore the integration of reproductive health services into HIV care and treatment programmes. We review the design and progress of the MTCT-Plus Initiative, which provides HIV care and treatment services to HIV positive women as well as their HIV positive children and partners. By emphasising the long-term follow-up of families and the provision of comprehensive care across the spectrum of HIV disease, MTCT-Plus highlights the potential synergies in linking reproductive health services to HIV care and treatment programmes. While HIV care and treatment programmes in resource-limited settings may not be able to integrate all reproductive health services into a single service delivery model, there is a clear need to include basic reproductive health services, such as access to appropriate contraception and counselling and management of unplanned pregnancies. The integration of these services would be facilitated by greater insight into the reproductive choices of HIV positive women and men, and into how health care providers influence access to reproductive health services of people with HIV and AIDS.

Africa South of the Sahara↗

PubMed2001

Leptin in reproduction.

In mammals, the function of the reproductive system is dependent on the availability of energy in the environment. It is well established that acute modifications of energy balance modulate the hypothalamic-pituitary-gonadal axis. In several species, fasting and caloric restriction have been shown to cause the suppression of pulsatile luteinizing hormone secretion, via an inhibition of the gonadotropin-releasing hormone pulse generator. Such a mechanism probably prevents energy being wasted for reproduction. By contrast, excessive energy storage and obesity interfere with the correct regulation of the reproductive axis. The identification of leptin and leptin receptors, along with studies performed in animal models of leptin deficiency and resistance, has focused attention on the role of this molecule in reproduction, and disclosed new aspects of the relationship between energy stores, adipose tissue and reproductive function. Here, we discuss the central and peripheral effects of leptin on reproductive tissues, and try to fit a complex reality into a simplified model. In particular, the roles of leptin in reproduction at different anatomical levels and in various clinical and experimental settings are discussed.

Animals↗

PubMed1999

Skeletal mass, chemistry, and growth during and after multiple reproductive cycles in the rat.

There are dramatic changes in skeletal physiology and metabolism to accommodate the mineral requirements of the developing fetus during pregnancy and milk production during lactation. The purpose of this study was to document changes in skeletal growth, chemistry, and mass during and after multiple reproductive cycles in the rat, with emphasis on the putative reconstitution of the skeleton after lactation. To determine skeletal changes, experimental groups included rats at the end of the first and second lactation, at the end of the second pregnancy, and at various times after the first and second lactation. These groups were also compared with aged-matched, nulliparous animals. There were decreases in femoral ash weights and bone mineral densities (BMDs) during the first and second lactations, but accelerated rates of gain after lactation, compared with the nulliparous controls. The changes in bone ash were even more pronounced when normalized to the maternal body weight changes during and after the reproductive cycles. The rates and amount of bone mineral (ash) gain after the first and second reproductive cycles were similar; however, neither bone mineral nor BMD returned to levels found in nulliparous animals after the first and subsequent reproductive cycle. There was also a decrease in ash/dry weight ratio of the femur during the second lactation, suggesting a preferential loss of more mineralized bone. This decrease in ash/dry weight ratio reversed after lactation, indicating a relative accumulation of bone mineral during the postlactational period. As expected, endochondral growth was substantially suppressed during lactation, but rebounded during the postlactational period. These data collectively support the notion that the female rat has excess skeletal mass to accommodate losses associated with the first reproductive cycle. After the first reproductive cycle, a new optimal skeletal mass is achieved. These data also demonstrate that the postlactational period is "anabolic" with accelerated rates of bone growth and accumulation of bone mineral and bone mineral density with increases in the ratios of the inorganic to organic composition of the bone. This postlactational recovery phase may serve to at least partially reconstitute skeletal mineral depleted during lactation and perhaps to prepare the skeleton for the next reproductive cycle.

Animals↗

PubMed1998

Reproductive cessation in female mammals.

In female mammals, fertility declines abruptly at an advanced age. The human menopause is one example, but reproductive cessation has also been documented in non-human primates, rodents, whales, dogs, rabbits, elephants and domestic livestock. The human menopause has been considered an evolutionary adaptation, assuming that elderly women avoid the increasing complications of continued childbirth to better nurture their current children and grandchildren. But an abrupt reproductive decline might be only a non-adaptive by-product of life-history patterns. Because so many individuals die from starvation, disease and predation, detrimental genetic traits can persist (or even be favoured) as long as their deleterious effects are delayed until an advanced age is reached, and, for a given pattern of mortality, there should be an age by which selection would be too weak to prevent the onset of reproductive senescence. We provide a systematic test of these alternatives using field data from two species in which grandmothers frequently engage in kin-directed behaviour. Both species show abrupt age-specific changes in reproductive performance that are characteristic of menopause. But elderly females do not suffer increased mortality costs of reproduction, nor do post-reproductive females enhance the fitness of grandchildren or older children. Instead, reproductive cessation appears to result from senescence.

Adaptation, Physiological↗

PubMed1991

A genetic analysis of reproductive barriers in Phacelia dubia.

Investigations into the genetic basis of reproductive barriers among recognized and putative varieties in Phacelia dubia have provided evidence that even among closely related taxa, multiple pathways can lead to reproductive isolation. A nuclear-based reproductive barrier, expressed as partial hybrid sterility of both pollen and ovules, isolated each pair of recognized varieties. There was no evidence of pre- or post-fertilization barriers; all reproductive barriers were manifested as hybrid gametic sterility. Reproductive relationships of two putative varieties were studied to examine the early stages of reproductive isolation in this group. Both putative varieties exhibited partial reproductive isolation from the recognized varieties in spite of their lack of morphological differentiation from recognized varieties. The barrier isolating one putative variety was similar to the barrier among recognized varieties. The second putative variety and a recognized variety were partially isolated by a unidirectional, nuclear-cytoplasmic barrier that reduced only pollen fertility. The nuclear-cytoplasmic barrier suggested a new application of Haldane's rule.

Alleles↗

PubMed2004

Social parasitism by male-producing reproductive workers in a eusocial insect.

The evolution of extreme cooperation, as found in eusocial insects (those with a worker caste), is potentially undermined by selfish reproduction among group members. In some eusocial Hymenoptera (ants, bees and wasps), workers can produce male offspring from unfertilized eggs. Kin selection theory predicts levels of worker reproduction as a function of the relatedness structure of the workers' natal colony and the colony-level costs of worker reproduction. However, the theory has been only partially successful in explaining levels of worker reproduction. Here we show that workers of a eusocial bumble bee (Bombus terrestris) enter unrelated, conspecific colonies in which they then produce adult male offspring, and that such socially parasitic workers reproduce earlier and are significantly more reproductive and aggressive than resident workers that reproduce within their own colonies. Explaining levels of worker reproduction, and hence the potential of worker selfishness to undermine the evolution of cooperation, will therefore require more than simply a consideration of the kin-selected interests of resident workers. It will also require knowledge of the full set of reproductive options available to workers, including intraspecific social parasitism.

Aggression↗

PubMed2001

The reproductive biology of Polytrichum formosum: clonal structure and paternity revealed by microsatellites.

Using highly polymorphic microsatellite markers, we assessed clonal structure and paternity in a population of the bryophyte species Polytrichum formosum. Identical multilocus genotypes of individual shoots were almost never observed in spatially separated cushions, but were found to be highly clustered within moss cushions. Therefore, asexual reproduction through dispersal of gametophyte fragments is not very important in P. formosum. However, asexual reproduction on a very localized scale through vegetative growth of genets (branching of gametophytes via clonal growth of rhizomes) is very extensive. The patchy spatial distribution of genets and the absence of intermingling among genets suggest that this species follows a 'phalanx' clonal growth strategy. Vegetative proliferation of genets will increase their size, and, consequently, will have considerable fitness consequences for individuals in terms of increased genet longevity and reproductive output. Although paternity analysis of sporophytes confirmed male genet size, i.e. gamete production, to be an important determinant of male reproductive fitness, it also showed that the spatial distance to female genets is the predominant factor that governs male reproductive success. Moreover, we showed that male gamete dispersal distances in P. formosum are much further than generally assumed, and are in the order of metres rather than centimetres. Combining the findings, we conclude that the high genotypic diversity observed for this facultatively clonal species is most likely explained by a preponderance of sexual reproduction over clonal reproduction.

Bryopsida↗

PubMed2004

Significant reproductive skew in the facultatively polygynous ant Pheidole pallidula.

Reproductive skew - the extent to which reproduction is unevenly shared between individuals in a social group - varies greatly between and within animal species. In this study, we investigated how queens share parentage in polygynous (multiple queen) colonies of the Mediterranean ant Pheidole pallidula. We used highly polymorphic microsatellites markers to determine parentage of gynes (new queens), males and workers in P. pallidula field colonies. The comparison of the genotypes of young and adult workers revealed a very low queen turnover (less than 2%). The first main finding of the study of reproductive skew in these colonies was that there was a significant departure from equal contribution of queens to gyne, male and worker production. Reproductive skew was greater for male production than for queen and worker production. There was no relationship between the magnitude of the reproductive skew and the number of reproductive queens per colony, their relatedness and the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, our study revealed for the first time a trade-off in the relative contribution of nestmate queens to gyne and worker production. The queens contributing more to gyne production contributed significantly less to worker production.

Animals↗

PubMedDate not supplied

Diet effects on female reproduction in high growth (hg/hg) mice that are deficient in the Socs-2 gene.

The detrimental effect of larger body size on reproductive performance has been well documented in mouse models of overgrowth, such as Growth Hormone (GH) transgenics. This study describes the reproductive performance of the High Growth (HG) mouse model of overgrowth. The HG mouse model exhibits overgrowth due to a partially recessive autosomal mutation that increases growth rate and mature body size. The HG phenotype results from the lack of expression of Socs-2, which negatively regulates GH signaling. C57BL/6J (C57) and congenic C57BL/6J-hg/hg (HG) female mice were fed four diets differing in protein and energy content, starting at 8 weeks of age. A complete reproductive cycle from mating to weaning was evaluated. HG mice were 40% larger than C57 and had a higher feed intake throughout the experiment. Significant genotype x diet interactions were detected for growth, body composition and reproductive traits. HG females showed poor reproductive performance compared to controls as demonstrated by their lower fertility during mating, which was not overcome by changes in the diet. No differences were detected in litter size, but HG animals exhibited a longer gestation length and heavier pup weaning weights compared to controls. Reproductive impairment in HG seems to be the consequence of the lack of Socs-2 independent of the effects of increased body size on reproduction.

Animals↗