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PubMed2001

Aggregation of whelks, Buccinum undatum, near feeding predators: the role of reproductive requirements.

In the Mingan Islands, northern Gulf of St Lawrence (eastern Canada), the whelk Buccinum undatum displays a strong escape response to its predator, the asteroid Leptasterias polaris, nevertheless large sexually mature individuals occasionally approach feeding L. polaris to obtain food. In this study, we investigated the hypothesis that reproductive requirements increase the tendency of sexually mature whelks to approach feeding asteroids. Prior to egg laying, females (which invest more energy than males into the production of reproductive structures) represented 72% of the adult whelks that approached feeding L. polaris, but only 36% of the adults randomly collected from the study area. Furthermore, females that were attracted to feeding asteroids had smaller reproductive organs (after accounting for body size) than females randomly collected from the study area. Similarly, prior to egg laying, females fed longer and ingested more food than males when tested in the presence of L. polaris in the laboratory. After egg laying, however, females and males displayed a similar tendency to feed in the presence of a predator, both in the field and in the laboratory. Predator-impact indices, computed by contrasting the feeding activity of whelks in the absence and presence of a predator, indicated that females (but not males) responded more boldly to predators prior to than after egg laying, despite a general decrease in feeding activity at that period. Taken together, our observations indicate that the tendency of adult whelks to approach feeding predators is influenced by potential reproductive gains. Because such gains are presumably more directly linked to a given feeding opportunity in sexually active individuals, whelks may be selected to display increased levels of boldness towards predators with the onset of sexual maturity. Thus, potential reproductive benefits may partly explain the size-dependent tendency of whelks to approach feeding asteroids. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2001

Paternity analysis of alternative male reproductive routes among the langurs (Semnopithecus entellus) of Ramnagar.

Because primate males usually invest very little in offspring, male reproductive success will mainly be determined by access to fertile females with differences in access leading to differential male reproductive success. To determine the outcome of alternative male reproductive routes, we investigated a wild population of Hanuman langurs at Ramnagar, South Nepal, where groups were either one-male or multimale. Paternity was established by DNA analysis from faeces for 42 infants in five groups. In one-male groups all infants were sired by the only resident male in the group. In multimale groups the alpha male fathered significantly more infants (57%) than all other resident males. Nonresident males sired at least 21% of all infants born into multimale groups. Because of the lower mean number of infants sired by alpha males during their whole tenure as alpha compared with males in one-male groups (2.3 versus 6.8) and the higher maximum value (8.9 versus 6.0), the alpha male route is considered the riskier option. Based on demographic data we suggest that the considerable variance in short-term reproductive success might not translate to the same degree into differences in long-term reproductive success. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Evaluation of the developmental and reproductive toxicity of chlorpyrifos in the rat.

Chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)-phosphorothioate), an organophosphate insecticide, was evaluated for its potential to produce developmental and reproductive toxicity in rats following oral exposure. Pregnant Fischer 344 rats were given doses of 0 (corn oil vehicle), 0.1, 3.0, or 15 mg chlorpyrifos/kg/day, by gavage, on Gestation Days 6 through 15. Maternal effects noted at the two higher dose levels included decreased cholinesterase levels at 3.0 mg/kg/day and cholinergic signs (excessive salivation and tremors), decreased cholinesterase levels, and decreased body weight gain at 15 mg/kg/day. No maternal effects were apparent at 0.1 mg/kg/day. Although maternal toxicity was observed at these two higher exposure levels, no developmental effects were noted at any dose. In a two-generation reproduction study, Sprague-Dawley rats were maintained on diets supplying 0, 0.1, 1.0, or 5.0 mg chlorpyrifos/kg/day. Parental effects included decreased plasma and erythrocyte cholinesterase at 1.0 mg/kg/day, and decreased plasma, erythrocyte, and brain cholinesterase and histopathologic alterations of the adrenal zona fasciculata at 5.0 mg/kg/day. The histopathologic alterations of the adrenal were characterized as very slight to slight vacuolation (consistent with fatty change) in males, and very slight vacuolation and/or altered tinctorial properties in females. No effects on the reproductive or fertility indices or on the histopathology of reproductive tissues were observed at any dose level, and no neonatal effects were observed at 0.1 or 1.0 mg/kg/day in the F1 or F2 litters. Parental toxicity at the high dose was accompanied by decreased pup body weight and increased pup mortality in the F1 litters only. These data show that oral administration of chlorpyrifos to rats at parentally toxic dose levels was not embryolethal, embryo/fetotoxic, or teratogenic and did not adversely affect fertility or the function or structure of the reproductive organs. Although effects on neonatal growth and survival were observed at a maternally toxic dose level in one generation, this effect was not observed in the subsequent generation and, therefore, may not have been related to treatment.

Administration, Oral↗
PubMed1994

Methyl farnesoate levels in male spider crabs exhibiting active reproductive behavior.

The concentration of methyl farnesoate (MF) in the hemolymph and its synthesis by the mandibular organs (MOs) were investigated to determine whether this compound is related to the differences in the size of the reproductive system and the mating behavior among male morphotypes of the spider crab, Libinia emarginata. Large-claw abraded males displayed mating behavior under competitive conditions. They have the largest reproductive systems, their MOs synthesize large amounts of MF in vitro, and the concentration of MF in their hemolymph is high. Small-claw abraded males displayed mating behavior with receptive females only when isolated. These smaller crabs have intermediate-sized reproductive systems, their MOs synthesize the most MF, and they have the highest circulating level of MF relative to their body size. The unabraded males did not display mating behavior; their reproductive systems are smaller; their MO activity is low, as is their circulating level of MF. The strong relationship between MF levels and the intensity of reproductive behavior suggests that MF may be one of the driving forces behind mating behavior in Crustacea.

Animals↗
PubMed1997

Deficits in reproductive behavior in diabetic female rats are due to hypoinsulinemia rather than hyperglycemia.

These studies determined whether deficits in reproductive behavior observed in streptozotocin (STZ)-induced diabetic female rats are caused by hyperglycemia or loss of insulin. Female Sprague-Dawley rats were ovariectomized and made diabetic by a single ip injection of STZ (75 mg/kg). Reproductive behavior was measured 12 days after the onset of hyperglycemia following the injection of estrogen and progesterone in doses known to restore reproductive behavior in nondiabetic rats. Rats in which STZ produced diabetes showed significantly reduced receptive and proceptive sexual behaviors. Normalization of blood glucose levels either by restricting diet or by phlorizin treatment failed to restore reproductive behavior in diabetic animals. However, even doses of insulin which were not fully effective in correcting peripheral hyperglycemia were able to prevent the STZ-induced behavioral deficit. No changes in general activity were observed in any experimental group as assessed by open field activity. The density of the norepinephrine transporter, as measured by [3H]nisoxetine binding, was reduced in the cortex but not in the brain stem, hypothalamus, or hippocampus of diabetic animals. Insulin treatment prevented the loss of cortical [3H]nisoxetine binding, and even partial normalization of blood glucose restored cortical [3H]nisoxetine binding to control levels. These findings suggest that diabetes-induced reproductive deficits are due to hypoinsulinemia and cannot be corrected simply by the normalization of blood glucose, whereas reductions in the density of cortical norepinephrine transporter result from hyperglycemia.

Animals↗
PubMed2000

Corticosterone treatment has no effect on reproductive hormones or aggressive behavior in free-living male tree sparrows, Spizella arborea.

We examined the effect of corticosterone on plasma levels of reproductive hormones (testosterone, dihydrotestosterone, and luteinizing hormone) and territorial defense behavior in male tree sparrows, Spizella arborea. Birds receiving Silastic implants filled with corticosterone (B) had significantly higher plasma levels of B than control birds, which received empty implants, and exhibited pectoral muscle wastage and a decrease in body mass. We evaluated the hormonal and agonistic responses of the two implanted groups of birds using a simulated territorial intrusion (STI) 2 to 4 days after they were implanted. Corticosterone-treated and control birds did not differ in their circulating levels of reproductive hormones or in their behavioral responses to STI (latency to respond to intrusion, number of songs, and closest approach to a decoy and tape recording). Unlike previous studies of north temperate passerines, high physiological levels of exogenous B had no effect either on circulating levels of reproductive hormones or on territorial behaviors associated with breeding. Nonetheless, untreated tree sparrows do mount a robust adrenocortical response, having a two- to fourfold increase in plasma B levels during a 1-h period of capture. Thus, adrenocortical responsiveness is maintained in these birds, but elevated levels of glucocorticoids do not suppress reproductive hormones or associated behaviors. We believe that this hormonal and behavioral refractoriness to glucocorticoids-or uncoupling of the stress response from the reproductive axis-may be advantageous for species having extreme temporal constraints on their breeding schedules.

Adrenal Cortex↗
PubMed1984

Substance P in primary afferent neurons of the female rat reproductive system.

The amount of substance P-immunoreactivity (SP-I) was studied in the female rat reproductive organs (uterus, cervix, vagina and ovary) in the diestrous and estrous stages of the estrous cycle, after ovariectomy and on days 7, 14 and 19 of pregnancy. The concentration of SP-I (pmol X g-1 tissue) was generally highest in the vagina followed by cervix, uterus and ovary. SP-I concentrations in all reproductive organs were significantly higher following ovariectomy but significantly lower during pregnancy compared to concentrations from intact rats. There were no significant differences in the total content of SP-I per organ during the estrous cycle, after ovariectomy or during pregnancy (cervix, vagina). SP-I concentrations were markedly reduced in the reproductive organs of adult rats treated with capsaicin as neonates. This led to the conclusion that SP in reproductive organs is present in primary afferent fibers. The findings indicate that the number of SP-I containing primary afferent fibers in the female reproductive organs are stable elements neither increasing nor decreasing in response to changing hormonal levels or to the tissue growth and differentiation occurring during the estrous cycle or pregnancy.

Animals↗
PubMed1993

The association between antibody titres against Campylobacter fetus and reproductive efficiency in dairy cattle.

The relationship between the antibody titres against Campylobacter fetus and various indices of reproductive efficiency was studied in a cross-sectional study of 178 dairy cows from three California Dairy Herd Improvement Association herds. Blood samples were collected from the lactating cows during December 1986. Enzyme-linked immunosorbent assays were used to determine the antibody titres of the cow against Campylobacter fetus, Haemophilus somnus and Leptospira hardjo and were classified as either negative or positive. The status of a cow as either negative or positive against Campylobacter fetus and Haemophilus somnus represents serological evidence of natural exposure to the corresponding bacterial agents. However, the status against Leptospira hardjo was assumed to reflect a vaccinal titre since all the cows studied had been routinely vaccinated against this organism in September 1986. The data on demographic and reproductive parameters pertained only to the current lactation of the cows and were obtained from Dairy Herd Improvement Association individual cow records of December 1986. Five indices of reproductive efficiency were used, namely the recent calving interval, the calving-to-conception interval, the calving-to-last-service interval, the number of services per conception, and the number of services since last calving. The serological status against Haemophilus somnus, Leptospira hardjo and other covariates suggested by the results of previous studies were included in modelling the relationships of interest. Stepwise multiple linear regression analyses were carried out to study the adjusted relationship of Campylobacter fetus with each measure of reproductive efficiency. Multivariate analyses revealed that the adjusted relationship for Campylobacter fetus with all five measures of reproductive efficiency was non-significant (p > 0.05). Among the covariates, Leptospira hardjo had a strong and independent relationship with recent calving interval, the unstandardized partial regression coefficient being -0.77. The possible biological mechanisms of these associations are discussed.

Animals↗
PubMed1992

Effects of megadoses of pyridoxine on spermatogenesis and male reproductive organs in rats.

Although it has been indicated that many neurotoxicants also cause reproductive toxicity, the reproductive toxicity of megadoses of pyridoxine, which is a neurotoxicant, has not been studied. In this paper, we studied the effects of megadoses of pyridoxine on male reproductive organs. Pyridoxine hydrochloride, 125 mg/kg, 250 mg/kg, 500 mg/kg or 1000 mg/kg, daily, was intraperitoneally injected into Wistar male rats 5 days a week for 2 or 6 weeks, and its effects on the male reproductive organs were investigated. After 2 weeks of administration, absolute weights of the testis in the 500 and 1000 mg/kg epididymis in all the exposed groups and prostate gland in the 1000 mg/kg group decreased, and mature spermatid counts in the testis decreased in the 1000 mg/kg group. After 6 weeks administration, the absolute and relative weights of the testis, epididymis, prostate gland and seminal vesicle decreased in the 500 mg/kg and 1000 mg/kg groups, and mature spermatid counts in the testis and sperm counts in the epididymis decreased in these groups. Among the marker enzymes of the testicular cells, LDH-X activity decreased, and beta-glucuronidase activity, cytochrome P-450 content and cytochrome b5 content increased in the 1000 mg/kg group. Plasma testosterone concentration did not significantly alter in all the exposed groups. From these results, it was concluded that megadoses of pyridoxine affected the spermatogenesis and decreased reproductive organ weights in the rat.

Animals↗
PubMed1995

A framework for establishing integrated reproductive health training.

The challenge for the next decade will be to make quality family planning services accessible to all sexually active couples who want them. The key to fulfilling this goal is the need to rapidly increase the availability of quality voluntary family planning services globally. This paper presents a framework for integrated reproductive health training which provides a mechanism for ensuring a continuous sustainable supply of qualified trainers and service providers. The paper discusses the approach used by JHPIEGO, a Johns Hopkins University program for international education in reproductive health, to build up national training capacity through the development of integrated reproductive health training. This approach may be seen as a network of pathways linking the national system of higher education, the health care system, the political system and cultural norms to strengthen reproductive health policy, training and services. National integrated reproductive health training includes: updated national policies and service guidelines, pre-service training in health professional schools to prepare students to provide family planning services upon graduation; in-service training for practicing health professionals to improve family planning skills for immediate application on the job; and development of clinical training sites at service delivery points already providing family planning/reproductive health services.

Family Planning Services↗
PubMed1996

Homeobox genes and male reproductive development.

PURPOSE: Homeobox genes encode transcription factors that dictate developmental events in philogenetically diverse organisms. In comparison to what is known about their role in embryogenesis, we know very little concerning homeobox gene function in neonates or adults. In this communication, we review studies that address the possible role of homeobox genes in male reproductive development, a system active in neonate and adult animals. METHODS: Studies have shown that many homeobox genes are expressed in germ cells of the testis, while less is known about the identity of homeobox genes expressed in somatic cells of the testis or epididymis. Hox homeobox genes display a pattern of expression in testis that is dependent on their paralogous and orthologous position within the Hox gene chromosome clusters. Other homeobox genes are expressed in the male reproductive system, including many POU and Prd/Pax homeobox gene family members. More recently, it has been shown that the orphan homeobox gene, Pem, originally isolated by subtraction hybridization on the basis of its differential expression in tumor cell lines, is selectively expressed in reproductive tissue. Alternatively spliced Pem transcripts accumulate in testis and epididymis that differ from those expressed in tumors and placenta. Pem transcripts accumulate postnatally in the epididymis in a developmentally regulated manner. CONCLUSIONS: The highly regulated pattern of expression exhibited by many homeobox genes in the male reproductive system suggests that homeobox transcription factors may dictate developmental events in this system. However, future studies are needed to determine the specific functional roles homeobox genes in male reproductive development and spermatogenesis.

Adult↗
PubMed2003

Is reproduction of the Australian house mouse (Mus domesticus) constrained by food? A large-scale field experiment.

Food quantity and especially food quality are thought to be key factors driving reproductive changes in the house mouse, Mus domesticus, leading to outbreaks of house mouse populations in the Australian grain-growing region. Characteristic changes during an incipient mouse plague are an early start of breeding, a high proportion of females breeding at a young age and a prolonged breeding season. We conducted a large-scale food manipulation during an incipient mouse plague, which started with early breeding and relatively high spring numbers of mice. We measured background food availability in four farms throughout the study and conducted a food manipulation experiment from November to March in two of them. After harvest in December 100-200 kg/ha spilled grain remained in the stubble. This was depleted by March. In two treatment farms we added high-protein food pellets on a weekly basis between November and March and two farms served as controls. We measured changes in mouse numbers by capture-mark-recapture trappings and changes in reproduction by scoring embryos and recent placental scars at necropsy. Mouse numbers did not differ between treatments and controls. There were no differences in the litter size or the proportion of females breeding between treatments and controls. We observed the normal pattern of high litter size in spring and decreasing litter size towards the end of summer in treatments and controls. In all farms reproduction stopped in March. Mouse numbers were high but not at plague densities. Contrary to our prediction we did not observe food constraint affecting the reproduction of female mice. Our field experiment seems to rule out food quality as the driving factor for improved reproduction and formation of an outbreak of mice. We suggest that physiological mechanisms in mice might not enable them to take advantage of food with a high protein content in arid summers in southeastern Australian grain fields because of the lack of free-standing water.

Adaptation, Physiological↗
PubMed2003

Food quality controls reproduction of the zebra mussel (Dreissena polymorpha).

Species such as Dreissena polymorpha sometimes contribute substantially in the transfer of primary to secondary production. During the ontogenetic cycle, the reproductive investment of adult mussels is one of the main parameters that affect recruitment success. We studied how food quality and temperature affect the reproductive investment in term of egg mass of D. polymorpha in a lake by sampling mussels monthly from 4 m and 15 m depths. Temperature affected reproduction directly and also indirectly through the food. To assess whether temperature and/or food conditions led to the differences observed in mussels sampled from the two depths, mussels were reared in the laboratory under two different temperature regimes for 3 months, simulating the temperature of the lake at 4 m and 15 m depth. Possible effects of food quality were tested at each temperature using four diets differing in fatty acid composition. Temperature played an important role as a trigger for spawning, and the type of diet clearly affected the reproductive investment. When the heterokont chromophyte alga Nannochloropsis limnetica, which is rich in polyunsaturated fatty acids (PUFAs) and long-chained PUFAs (>C18), was fed to mussels, an increased egg mass was obtained. This result was in contrast to that found when the green alga Scenedesmus obliquus and the cyanobacterium Aphanothece sp., both of which are deficient in long-chained PUFAs, were offered as food to the mussels. Such a PUFA-dependent food quality may affect reproduction in lakes. Food quality effects vary seasonally in a lake and may be most important in summer, when low-food-quality green algae and cyanobacteria are abundant. The low biochemical quality of these blooms may affect at least the later period of gametogenesis of D. polymorpha, which reproduces from June to August.

Animals↗
PubMed2003

Growth or reproduction? Resource allocation by female frogs Rana temporaria.

The decision how to allocate marginal resources to reproduction and growth can have important effects on associated life-history parameters as well as on population dynamics. In addition to showing variation among individuals in a population, such allocation rules may be either condition-dependent or fixed in different individuals. While many studies on anuran amphibians have focused on egg numbers and egg sizes in females of different sizes, virtually no data exist on the relative allocation of marginal resources to growth versus reproduction. In the laboratory, we therefore offered female common frogs ( Rana temporaria) low versus high food rations for a full reproductive cycle, and monitored their growth and later reproductive investment (egg number and egg size the following breeding season). Feeding rates had an effect both on female growth and on egg number and size. There was no trade-off found between the two forms of investment. A flexible allocation rule could not be supported as there was no significant effect of feeding rate on the relative allocation of resources to growth versus reproduction.

Adaptation, Physiological↗
PubMed2002

Quantitative analysis of carbon balance for reproduction in woody species.

The carbon balance in reproductive organs over the whole reproductive period was estimated for 20 woody species on the basis of the published data on the final dry weight and CO(2) exchange of reproductive organs. The relationship between net respiration and dry weight growth was formulated by a linear function with a negative y-intercept. From this linear relationship, linear relations of dry weight growth and net respiration to net translocation were derived. The size dependence of net respiration showed that the net respiration changed from negative to positive as the final dry weight of the reproductive organ exceeded 0.481 g. The cost for translocation per unit dry weight was much lower in the species with small reproductive organs (<0.481 g) because of their photosynthetic contribution to the weight growth. The relation of dry weight growth/net translocation ratio to net translocation was expressed as a hyperbolic function. The dry weight growth/net translocation ratio remained at 0.650, in the higher range of net translocation, irrespective of woody species.

Journal Article↗
PubMed2005

The impact of reproductive factors on breast cancer risk--the feasibility of using Swedish population-based registers to account for the effect of confounding in cohort studies.

OBJECTIVE: The aim of this study was to analyze the impact of reproductive factors on breast cancer risk among Swedish women by using nationwide population registers. METHODS: A cohort including all Swedish women born between 1920 and 1959 was followed up to 1997 by record linkage to different population-based registers. More than 4 million children were linked to the women in the cohort and 60,328 women were diagnosed with breast cancer. Poisson regression was used to model the breast cancer incidence by risk groups. In a sub-cohort of 18,164 women irradiated for skin hemangioma in infancy, the breast cancer risk was analyzed in relation to radiation dose and accounting for reproductive factors. RESULTS: The relative breast cancer risk (RR) for the reproductive factors was 0.35 [ 95% confidence interval (CI) 0.30--0.42] for women with 6 or more children and the first child before the age of 20 years, and RR was 1.11 (95% CI 1.06--1.18) for uniparous women with the first child at age 35 years or older, compared to nulliparous women. The discrepancies of reproductive factors in the hemangioma cohort compared to Swedish women had a minor effect on RR, with a reduction from 1.13 (95%CI 1.00--1.26) to 1.11 (95% CI 0.99--1.25). CONCLUSIONS: This study shows the feasibility of using population-based registers to retrieve reliable information on reproductive factors to eliminate its confounding effect when analyzing other risk factors.

Age Factors↗
PubMed2006

Application of ultrasonography in the study of the reproductive system of tropical jennies (Equus asinus).

The use of high-frequency (5 MHz) ultrasonography was studied in 11 jennies (7 non-pregnant and 4 pregnant) to characterize the reproductive organs and follicular activities at different stages of reproduction. The result showed close similarity with the mare. The visibility of endometrial folds increased towards ovulation. A positive correlation (p < 0.001; tau = 0.79) was found between the score of the folds and the size of the dominant follicle. The diameter of the uterus and the size of the dominant follicle were significantly correlated (p < 0.001; r = 0.80). In pregnant jennies, an embryonic vesicle was detectable at 14 days. Follicular growth was characterized by more than one wave. The smallest ovarian follicle was 2 mm and the largest 40mm. Depending on the reproductive stage, up to 13 follicles were detected per ovary. After monitoring 84 cycles, a mean (+/- SD) diameter of 34.4 +/- 3.6 mm (27.5-40.2 mm) of the preovulatory follicle and 67.85% incidence of single ovulation were found. The mean (+/-SD) interovulatory interval was 25.7 +/- 6 days. This study proved that high-frequency ultrasonography is highly effective in characterizing the reproductive organs and follicular activity of jennies and could be useful in the reproductive management of donkeys.

Animals↗
PubMed1989

Commentary on women-centered reproductive health services.

From women's perspectives, the primary principles of a reproductive health framework in the developing world are as follows: Family planning is a basic human right to which all human beings are entitled. Provision of family planning services must be comprehensive, including safe and low cost methods, freedom of choice about both contraception and pregnancy termination, timely and honest information, privacy and confidentiality, individual needs assessment, and counseling of women, men or the couple. Wide contraceptive choice requires more research on methods that are less invasive of women's anatomy and physiology and more supportive of women's control of their own bodies. These parameters of quality care in family planning must be centered on women's needs, desires and expectations. The concept of conscious contraception implies an attitude of conscious sexuality. When a woman accepts that sexual gratification independent of reproduction is a legitimate right, she is better prepared to engage in the pursuit of her own health and happiness. If family planning programs do not include sexuality as a key issue to discuss with clients, all long-term strategies will fall short in modifying people's attitudes, especially women's reluctance to contracept. Sexual and reproductive health includes emotional health. As Dr. Sai points out, the effects of underdevelopment and poverty strike women in dramatic ways, and quite often all the pressures to which they are exposed lead to precarious emotional health. They become victims of violence and repeat the cycle of violence with their children. We, as advocates of sexual and reproductive rights, must also consider the psychological and emotional implications of sexuality and reproduction, and learn to deal with them in our clinics and services.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Illegal↗