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Sexual Maturation (sexual + maturation)
Selected AbstractsPost-natal Changes in Testicular Concentrations of Interleukin-1 Alpha and Beta and Interleukin-6 during Sexual Maturation in BullsREPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2010ET Bagu Contents Based on observations in laboratory animals interleukins could be regulators of testicular development. The objects of this study were to see if interleukins (IL-1 and IL-6) are present in the developing bull testis and to establish the temporal patterns of concentrations of IL-1 and IL-6 in the bovine testis during development. Separate groups of six bull calves were castrated every 4 weeks from 5 to 33 weeks of age, and at 56 weeks of age. Mean testicular IL-1 alpha concentrations decreased (p < 0.01) from 5 to 9 weeks of age and 13 to 21 weeks of age. Mean testicular IL-1 beta concentrations decreased (p < 0.01) from 13 to 17 weeks of age and from 29 to 33 weeks of age. Mean IL-1 bioactivity increased from 13 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks, decreased to 29 weeks and decreased from 33 to 56 weeks of age (p < 0.05). Mean testicular IL-6 concentrations decreased (p < 0.05) from 9 to 13 weeks of age, increased (p < 0.05) to 21 weeks, decreased (p < 0.05) to 25 weeks, increased (p < 0.05) to 29 weeks and decreased (p < 0.01) to 56 weeks of age. In conclusion, testicular IL-1 alpha, IL-1 beta and IL-6 were found in the bovine testis and concentrations were age dependent. Testicular IL-1 alpha and IL-1 beta concentrations were highest in the early post-natal period; however, IL-1 bioactivity and IL-6 concentrations were greatest in the immediate pre-pubertal period. These findings suggest a functional role for interleukins in testicular development in the bull. [source] The biosynthesis of Juvenile Hormone, its degradation and titres in females of the true armyworm: a comparison of migratory and non-migratory populationsPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2000Jeremy N. McNeil Summary In a previous study [McNeil et al. (1996) Archives of Insect Biochemistry and Physiology, 32, 575,584], patterns of sexual maturation and Juvenile Hormone (JH) biosynthesis were compared in virgin females from migratory (North American) and non-migratory (Azorean) populations of the true armyworm moth, Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae). Sexual maturation occurred at a significantly earlier age after emergence in the non-migrant population, and the rates of biosynthesis of JH in vitro suggested that lower titres of JH may be required to initiate the onset of calling behaviour (pheromone emission) and ovarian development in Azorean females. To examine the physiological differences in the reproductive biology of migratory and non-migratory populations in greater detail, the haemolymph titres of JH and JH esterase activity were compared in virgin females as a function of age. In addition, the effects of mating on JH biosynthesis in vitro, JH titres, JH esterase activity and egg production were measured in the two populations. As expected, JH titres rose more rapidly after emergence in Azorean females than in their North American counterparts but, contrary to our prediction, the maximum levels were also higher in the non-migrant population. Activity of JH esterase was much higher in Azorean females on the day of emergence. However, by the second day both populations had similar activity levels (about 17 nmol JH/min/ml) and exhibited a similar age-related decline in subsequent days. Mating did not affect the rate of JH biosynthesis in vitro but resulted in a significant increase in the titres of JH in the haemolymph of both populations. The maximum titre (a five-fold increase) occurred within 24 h of mating in Azorean females. In North American individuals the increase was greater (seven-fold) but did not occur until 48 h after mating. No difference in the activity of JH esterase was observed between mated and virgin North American females. By contrast, while there was an age-related decline in the activity of JH esterase in mated Azorean females, as seen in both North American groups, activity levels in virgin females remained constant with age. In all females, mating resulted in a significant increase in egg production within 24 h. The Azores is a volcanic archipelago, so these non-migratory populations were probably founded by immigrants originating from migratory continental populations. It is clear from our results that the change from a life history that includes migration to a non-migratory one involved more than just a temporal shift in the timing of the production of JH. Furthermore, the interpopulation differences in titres of JH and mating-induced changes reported here cannot be fully explained by the observed differences in the patterns of activity of JH esterase and JH biosynthesis in vitro. [source] Survival, growth and dressing traits of triploid hybrids between rainbow trout and three charr speciesAQUACULTURE RESEARCH, Issue 4 2000J M. Blanc Triploid hybrids between female rainbow trout Oncorhynchus mykiss and male brook charr Salvelinus fontinalis, Arctic charr S. alpinus and lake charr S. namaycush, together with diploid and triploid rainbow trout controls from the same dams, were tested in freshwater farming up to their fourth year of life. All hybrids displayed lower survival rates than the controls, the weakest genotype being the Arctic charr hybrid. Mortalities were mostly observed at the embryonic and larval stages and at the adult stage as a consequence of male sexual maturation. Growth of all hybrids was hindered (compared with controls) during the first year, but only moderate differences remained after 3 years. Sexual maturation resulted in a weight inferiority of males in all genotypes. As to carcass traits, female hybrids displayed a slightly higher dressing percentage than female triploid rainbow trout, as a result of lower visceral losses. These results are discussed with reference to hybrid resistance to rhabdoviruses from the viewpoint of fish farming improvement. [source] Reproductive effects of the endocrine disruptor fenarimol on a Baltic amphipod Monoporeia affinisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Therese Jacobson Abstract An endocrine disruptor, the fungicide fenarimol, was investigated regarding its effects on reproduction and hormone (ecdysteroid) levels in the deposit-feeding amphipod Monoporeia affinis. In addition, the influence of food shortage, both by itself and in combination with fenarimol, on reproduction was examined. Field-collected amphipods were exposed in flow-through microcosms during the period of sexual maturation and mating in four treatment series: Control with low food, fenarimol with low food, control with high food, and fenarimol with high food. Fenarimol was added at a concentration of 0.3 mg/L in two pulses/week. Results show that fenarimol has a negative effect on fertilization rate and male mating ability. Results were supported by a tendency toward delayed male sexual development. Food shortage decreased weight in both sexes and retarded female oocyte development. Higher ecdysteroid levels were recorded in males than in females, and food shortage increased male ecdysteroid levels. No effect of fenarimol exposure on ecdysteroid levels was observed. No synergistic effects of fenarimol and food shortage could be distinguished in any variable examined. Thus, M. affinis was vulnerable to reproductive impairment by fenarimol, with effects on the next generation (i.e., a disturbed sexual development and fertilization ability). Food shortage has negative effects on M. affinis, but it does not enhance the effects of fenarimol. [source] INVESTIGATING EVOLUTIONARY TRADE-OFFS IN WILD POPULATIONS OF ATLANTIC SALMON (SALMO SALAR): INCORPORATING DETECTION PROBABILITIES AND INDIVIDUAL HETEROGENEITYEVOLUTION, Issue 9 2010Mathieu Buoro Evolutionary trade-offs among demographic parameters are important determinants of life-history evolution. Investigating such trade-offs under natural conditions has been limited by inappropriate analytical methods that fail to address the bias in demographic estimates that can result when issues of detection (uncertain detection of individual) are ignored. We propose a new statistical approach to quantify evolutionary trade-offs in wild populations. Our method is based on a state-space modeling framework that focuses on both the demographic process of interest as well as the observation process. As a case study, we used individual mark,recapture data for stream-dwelling Atlantic salmon juveniles in the Scorff River (Southern Brittany, France). In freshwater, juveniles face two life-history choices: migration to the ocean and sexual maturation (for males). Trade-offs may appear with these life-history choices and survival, because all are energy dependent. We found a cost of reproduction on survival for fish staying in freshwater and a survival advantage associated with the "decision" to migrate. Our modeling framework opens up promising prospects for the study of evolutionary trade-offs when some life-history traits are not, or only partially, observable. [source] Kisspeptin/GPR54 system as potential target for endocrine disruption of reproductive development and functionINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2010M. Tena-Sempere Summary Kisspeptins, the products of Kiss1 gene acting via G protein-coupled receptor 54 (also termed Kiss1R), have recently emerged as essential gatekeepers of puberty onset and fertility. Compelling evidence has now documented that expression and function of hypothalamic Kiss1 system is sensitive not only to the activational effects but also to the organizing actions of sex steroids during critical stages of development. Thus, studies in rodents have demonstrated that early exposures to androgens and oestrogens are crucial for proper sexual differentiation of the patterns of Kiss1 mRNA expression, whereas the actions of oestrogen along puberty are essential for the rise of hypothalamic kisspeptins during this period. This physiological substrate provides the basis for potential endocrine disruption of reproductive maturation and function by xeno-steroids acting on the kisspeptin system. Indeed, inappropriate exposures to synthetic oestrogenic compounds during early critical periods in rodents persistently decreased hypothalamic Kiss1 mRNA levels and kisspeptin fibre density in discrete hypothalamic nuclei, along with altered gonadotropin secretion and/or gonadotropin-releasing hormone neuronal activation. The functional relevance of this phenomenon is stressed by the fact that exogenous kisspeptin was able to rescue defective gonadotropin secretion in oestrogenized animals. Furthermore, early exposures to the environmentally-relevant oestrogen, bisphenol-A, altered the hypothalamic expression of Kiss1/kisspeptin in rats and mice. Likewise, maternal exposure to a complex cocktail of endocrine disruptors has been recently shown to disturb foetal hypothalamic Kiss1 mRNA expression in sheep. As a whole, these data document the sensitivity of Kiss1 system to changes in sex steroid milieu during critical periods of sexual maturation, and strongly suggest that alterations of endogenous kisspeptin tone induced by inappropriate (early) exposures to environmental compounds with sex steroid activity might be mechanistically relevant for disruption of puberty onset and gonadotropin secretion later in life. The potential interaction of xeno-hormones with other environmental modulators (e.g., nutritional state) of the Kiss1 system warrants further investigation. [source] Reproduction in puyen, Galaxias maculatus (Pisces: Galaxiidae), in the southernmost extreme of distributionJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2007C. C. Boy Summary Reproductive aspects of a peripheral population of Galaxias maculatus are described and the relationship with the physiology and handling of energetic reserves under marginal environmental conditions is investigated. The G. maculatus population of Tierra del Fuego has an extended reproductive season, with differences in timing and duration compared to other populations of continental Patagonia, New Zealand and Australia. Elevated gonadosomatic indexes (IG) were observed during this period in both sexes (maximum IG = 33.49% males; 35.94% females). The high abundance of mature males (with high IG values) on the spawning grounds during the reproductive season suggests that they were waiting for the return of the mature females. Larger females reached total maturation at the beginning of the reproductive season, whereas the size of maturing females diminished toward the end (mean TL = 96 mm, October; 70 mm, February). Both sexes showed an extremely high investment in reproduction, reaching a maximum IG of about 35% for both sexes. At the beginning of the reproductive season females reached the maximum median IH (3.37%) and males the minimum (0.96%), suggesting differences in the role of the liver in the management of energetic reserves during sexual maturation. The variation in the fat index (IF) suggests that fat reserves were used to survive winter (maximum median IF > 1%, autumn; minimum about 0.2%, spring). [source] Immunocytochemical studies of the gonadotropic cells in the pituitary gland of male mullet, Mugil cephalus, during the annual reproductive cycle in both natural habitat and captivityJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2000M. A. Mousa Summary Using antiserum specific for the , subunit of coho salmon gonadotropic hormone II (GTH II), an immunocytochemical study of Mugil cephalus (L.) pituitaries was conducted during the annual reproductive cycle of the male in both natural habitat and captivity. The gonadotropic potency of the pituitary gland in general underwent an obvious increase during testicular development, reaching a peak at the time of reproductive maturity. During the testicular cycle of M. cephalus, the GTH cells showed an increase in immunoreactive staining intensity, granulation, hypertrophy and hyperplasia during sexual maturation. However, degranulation, vacuolization, and weakened immunoreactivity of these cells occurred during spawning. The GTH cells in the pituitary gland of M. cephalus males reared in captivity appeared with high synthetic and secretory activity but the reproductive activity declined, as reflected in the form of low values of the gonadosomatic index (GSI) and earlier resorption of the testes. [source] Effect of lindane on CYP-mediated steroid hormone metabolism in male mice following in utero exposureJOURNAL OF APPLIED TOXICOLOGY, Issue 8 2009Emma Di Consiglio Abstract A wide number of pesticides, including highly persistent organochlorinated compounds, such as lindane (LIN), may induce reproductive and developmental alterations by directly binding to the estrogen/androgen receptors or altering steroid hormone metabolism. In the present work, we have investigated whether LIN in utero exposure of CD1 mice affects the reproductive system in male offspring by causing an impairment of the CYP-dependent steroid hormone metabolism. Dam exposure to 25 mg kg,1 b.w. LIN occurred during critical developmental periods, from gestational days 9 to 16. Effects on hepatic CYP-mediated testosterone (TST) hydroxylase, aromatase activities and testicular parameters were tested at postnatal days (PND 50, 65,69, 100) that are critical for sexual maturation in CD1 mice. In the adult F1 mice significant changes of male reproductive endpoints (testis weight, spermatid number) as well as dramatic effects on CYP-mediated TST metabolism were observed on PND 65,69, in the absence of any of systemic toxicity. The levels of TST 6, - and 2, -hydroxylation and dehydrogenation showed the highest level of reduction, suggesting CYP 3A and 2C families as the major target of LIN induced effects. All changes were almost recovered on PND 100. No effects on aromatase activity were evidenced. Overall, these findings provide useful information for a better characterization of the LIN mode of action. They suggest that LIN-induced toxicity in males is linked to an impairment of steroid hormone homeostasis, due to CYP-mediated TST catabolism modulation and differs from LIN receptor-mediated mechanism previously reported in females. Copyright © 2009 John Wiley & Sons, Ltd. [source] Estrogen Receptor-, Inhibits Skeletal Growth and Has the Capacity to Mediate Growth Plate Fusion in Female Mice,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2004AS Chagin Abstract To determine the long-term role of ER, in the regulation of longitudinal bone growth, appendicular and axial skeletal growth was followed and compared in female ER,,/,, ER,,/,, and ER,,/,,,/, mice. Our results show that ER, inhibits appendicular and axial skeletal growth and has the capacity to induce fusion of the growth plates. Introduction: Estrogen affects skeletal growth and promotes growth plate fusion in humans. In rodents, the growth plates do not fuse after sexual maturation, but prolonged treatment with supraphysiological levels of estradiol has the capacity to fuse the growth plates. It should be emphasized that the estrogen receptor (ER),,/, and the ER,,/,,,/,, but not the ER,,/,, mouse models have clearly increased serum levels of estradiol. Materials and Methods: The skeletal growth was monitored by X-ray and dynamic histomorphometry, and the growth plates were analyzed by quantitative histology, calcein double labeling, bromodeoxyuridine (BrdU) incorporation, and TUNEL assay in 4- and 18-month-old female ER,,/,, ER,,/,, and ER,,/,,,/, mice. Results: Young adult (4-month-old) ER,,/, mice demonstrated an increased axial- and appendicular-skeletal growth, supporting the notion that ER, inhibits skeletal growth in young adult female mice. Interestingly, the growth plates were consistently fused in the appendicular skeleton of 18-month-old female ER,,/, mice. This fusion of growth plates, caused by a prolonged exposure to supraphysiological levels of estradiol in female ER,,/, mice, must be mediated through ER, because old ER,,/,,,/, mice displayed unchanged, unfused growth plates. Conclusions: Our results confirm that ER, is a physiological inhibitor of appendicular- and axial-skeletal growth in young adult female mice. Furthermore, we made the novel observation that ER,, after prolonged supraphysiological estradiol exposure, has the capacity to mediate growth plate fusion in old female mice. [source] Diet and social conditions during sexual maturation have unpredictable influences on female life history trade-offsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2009E. L. B. BARRETT Abstract The trade-off between gametes and soma is central to life history evolution. Oosorption has been proposed as a mechanism by which females can redirect nutrients invested in oocytes into survival when conditions for reproduction are poor. Although positive correlations between oocyte degradation and lifespan have been documented in oviparous insects, the adaptive significance of this process in species with more complex reproductive biology has not been explored. Further, environmental condition is a multivariate state, and combinations of environmental stresses may interact in unpredictable ways. Previous work on the ovoviviparous cockroach, Nauphoeta cinerea, revealed that females manipulated to mate late relative to sexual maturation experience age-related loss in fecundity because of loss of viable oocytes via apoptosis. This loss in fecundity is correlated with a reduction in female mate choice. Food deprivation while mating is delayed further increases levels of oocyte apoptosis, but the relationship between starvation-induced apoptosis and life history are unknown. To investigate this, virgin females were either fed or starved from eclosion until provided with a mate at a time known to be suboptimal for fertility. Following mating, females were fed for the duration of their lifespan. We measured lifetime reproductive performance. Contrary to predictions, under conditions of delayed mating opportunity, starved females had greater fecundity, gave birth to more high-quality offspring and had increased longevity compared with that of fed females. We suggest that understanding proximal mechanisms underlying life history trade-offs, including the function of oocyte apoptosis, and how these mechanisms respond to varied environmental conditions is critical. [source] Differential effects of genotoxic stress on both concurrent body growth and gradual senescence in the adult zebrafishAGING CELL, Issue 2 2007Stephanie B. Tsai Summary Among vertebrates, fish and mammals show intriguing differences in their growth control properties with age. The potential for unlimited or indeterminate growth in a variety of fish species has prompted many questions regarding the senescent phenomena that appear during the aging process in these animals. Using zebrafish as our model system, we have attempted in our current study to examine the growth phenomena in fish in relation to the onset of senescence-associated symptoms, and to evaluate the effects of genotoxic stress on these processes. We observed in the course of these analyses that the zebrafish undergoes continuous growth, irrespective of age, past the point of sexual maturation with gradually decreasing growth rates at later stages. Animal population density, current body size and chronological age also play predominant roles in regulating zebrafish growth and all inversely influence the growth rate. Interestingly, the induction of genotoxic stress by exposure to ionizing radiation (IR) did not adversely affect this body growth ability in zebrafish. However, IR was found to chronically debilitate the regeneration of amputated caudal fins and thereby induce high levels of abnormal fin regeneration in the adult zebrafish. In addition, by resembling and mimicking the natural course of aging, IR treatments likewise enhanced several other symptoms of senescence, such as a decline in reproductive abilities, increased senescence-associated ,-galactosidase activity and a reduction in melatonin secretion. Our current data thus suggest that during the lifespan of zebrafish, the onset of senescence-associated symptoms occurs in parallel with continuous growth throughout mid-adulthood. Moreover, our present findings indicate that genotoxic DNA damage may play a role as a rate-limiting factor during the induction of senescence, but not in the inhibition of continuous, density-dependent growth in adult zebrafish. [source] Timing and rate of sexual maturation of European eel in brackish and freshwater environmentsJOURNAL OF FISH BIOLOGY, Issue 2006D. Bevacqua Maturation rates in three European eel Anguilla anguilla populations increased from September to October and were slightly lower in fresh water than in brackish waters. Average and variance of total length at maturation were larger in females than males. [source] Biochemical composition of the Atlantic bonito Sarda sarda from the Aegean Sea (eastern Mediterranean Sea) in different stages of sexual maturityJOURNAL OF FISH BIOLOGY, Issue 2 2006N. Zaboukas The content (% wet mass) in water, ash, lipid, crude protein, DNA and RNA of different tissues was determined during sexual maturation of bonitos Sarda sarda from the Aegean Sea. A total of 220 specimens were collected in the following stages of sexual maturity: immature, resting, developing, mature, spawning and spent. Highest lipid levels in the white muscle, red muscle and liver were measured in immature specimens, while lowest levels were found in spawning bonitos. The gradual percentage of lipid reduction from immature to spawning bonitos was relatively higher in the liver (females 71·2% and males 64·4%) than in the white (females 59·2% and males 53·5%) and red (females 62·1% and males 51·7%) muscle. Lipid levels in the gonads increased gradually from the immature to spawning stage. The decrease of lipid in the somatic tissues was more intense in females than in males, and gonadal lipid content was higher in females than in males. There was a strong reverse correlation between water and lipid percentage in all tissues. Protein content decreased significantly only in spawning bonitos. The percentage of protein reduction from immature to spawning stage was relatively higher in males than in females in both white (females 3·4% and males 4·6%) and red (females 4·6% and males 5·1%) muscles. Protein content in the liver was significantly lower than in the other tissues, being highest in mature females. Gonadal protein content in females increased with maturation and decreased after spawning. The content in ash exhibited considerable stability. The RNA:DNA ratio exhibited a similar pattern of variation in both muscles. The RNA:DNA ratio increased during gonadal development gradually from the developing to spent stage. It was concluded that in S. sarda during gonadal development, there was an increase in gonadal lipid accompanied by a decrease in somatic tissue lipid reserves. Thus, reproductive inactive bonitos have more lipid in their edible part and a higher nutritional value than active ones. [source] Cognitive profile in a large french cohort of adults with Prader,Willi syndrome: differences between genotypesJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 3 2010P. Copet Abstract Background Prader,Willi syndrome (PWS) is a rare genetic disorder characterised by developmental abnormalities leading to somatic and psychological symptoms. These include dysmorphic features, impaired growth and sexual maturation, hyperphagia, intellectual delay, learning disabilities and maladaptive behaviours. PWS is caused by a lack of expression of maternally imprinted genes situated in the 15q11-13 chromosome region. The origin is a ,de novo' deletion in the paternal chromosome in 70% of the cases and a maternal uniparental disomy in 25%. The two main genotypes show differences, notably regarding cognitive and behavioural features, but the mechanisms are not clear. This study assessed cognitive impairment in a cohort of adults with genetically confirmed PWS, analysed their profiles of cognitive strengths and weaknesses, and compared the profiles in terms of genotype. Methods Ninety-nine male and female adults participated, all inpatients on a specialised unit for the multidisciplinary care of PWS. The Wechsler Adult Intelligence Scale (WAIS-III) was administered to all patients in identical conditions by the same psychologist. Eighty-five patients were able to cope with the test situation. Their scores were analysed with non-parametric statistical tools. The correlations with sex, age and body mass index were explored. Two genotype groups were compared: deletion (n = 57) and non-deletion (n = 27). Results The distribution of intelligence quotients in the total cohort was non-normal, with the following values (medians): Full Scale Intelligence Quotient (FSIQ): 52.0 (Q1:46.0; Q3:60.0), Verbal Intellectual Quotient (VIQ): 53.0 (Q1:48; Q3:62) and Performance Intellectual Quotient (PIQ): 52.5 (Q1:48; Q3:61). No correlation was found with sex, age or body mass index. Comparison between groups showed no significant difference in FSIQ or VIQ. PIQ scores were significantly better in the deletion group. The total cohort and the deletion group showed the VIQ = PIQ profile, whereas VIQ > PIQ was observed in the non-deletion group. The subtest scores in the two groups showed significant differences, with the deletion group scoring better in three subtests: object assembly, picture arrangement and digit symbol coding. Some relative strengths and weaknesses concerned the total cohort, but others concerned only one genotype. Discussion We documented a global impairment in the intellectual abilities of a large sample of French PWS patients. The scores were slightly lower than those reported in most other studies. Our data confirmed the previously published differences in the cognitive profiles of the two main PWS genotypes and offer new evidence to support this hypothesis. These results could guide future neuropsychological studies to determine the cognitive processing in PWS. This knowledge is essential to improve our understanding of gene-brain-behaviour relationships and to open new perspectives on therapeutic and educational programmes. [source] Morphological Evidence for Direct Interaction Between Gonadotrophin-Releasing Hormone Neurones and Astroglial Cells in the Human HypothalamusJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2007M. Baroncini In rodents, there is compelling evidence indicating that dynamic cell-to-cell communications involving cross talk between astroglial cells (such as astrocytes and specialised ependymoglial cells known as tanycytes) and neurones are important in regulating the secretion of gonadotrophin-releasing hormone (GnRH), the neurohormone that controls both sexual maturation and adult reproductive function. However, whether such astroglial cell,GnRH neurone interactions occur in the human brain is not known. In the present study, we used immunofluorescence to examine the anatomical relationship between GnRH neurones and glial cells within the hypothalamus of five women. Double-staining experiments demonstrated the ensheathment of GnRH neurone perikarya by glial fibrillary acidic protein (GFAP)-immunoreactive astrocyte processes in the periventricular zone of the tuberal region of the hypothalamus. GFAP immunoreactivity did not overlap that of GnRH at the GnRH neurone's projection site (i.e. the median eminence of the hypothalamus). Rather, human GnRH neuroendocrine fibres were found to be closely associated with vimentin or nestin-immunopositive radial gial processes likely belonging to tanycytes. In line with these light microscopy data, ultrastructural examination of GnRH-immunoreactive neurones showed numerous glial cells in direct apposition to pre-embedding-labelled GnRH cell bodies and/or dendrites in the infundibular nucleus, whereas postembedding immunogold-labelled GnRH nerve terminals were often seen to be enwrapped by glial cell processes in the median eminence. GnRH nerve button were sometimes visualised in close proximity to fenestrated pituitary portal blood capillaries and/or evaginations of the basal lamina that delineate the pericapillary space. In summary, these data demonstrate that GnRH neurones morphologically interact with astrocytes and tanycytes in the human brain and provide evidence that glial cells may contribute physiologically to the process by which the neuroendocrine brain controls the function of GnRH neurones in humans. [source] The Effect of Leptin on Luteinizing Hormone Release Is Exerted in the Zona Incerta and Mediated by Melanin-Concentrating HormoneJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2000J. F. Murray Abstract The adipose hormone, leptin, not only restrains appetite, but also influences energy expenditure. One such influence is to promote sexual maturation and fertility. The neuromodulatory circuits that mediate this effect are not well known but the present study suggests that one mediator could be melanin-concentrating hormone (MCH). We show that the long-form receptor (Ob-Rb) is expressed in the zona incerta of the rat and that administration of leptin (both 0.5 µg and 1.0 µg/side) into this area of ovariectomized, oestrogen-primed rats stimulated the release of luteinizing hormone (LH) within 1 h, the effect enduring for a further 1 h. Injections of leptin into the arcuate nucleus induced a smaller, transient rise in LH while injections into the paraventricular and ventromedial nuclei were without effect. MCH neurones are present in the zona incerta and administration of this hormone into the medial preoptic area (mPOA) stimulates LH release, therefore we investigated the possibility that MCH might mediate this effect of leptin. An injection of MCH antiserum into mPOA prevented the rise in LH normally induced by leptin injected into the zona incerta. In addition, melanocortin receptor antagonists ([D-Arg8]ACTH(4-10) and [Ala6]ACTH(4-10)), previously shown to inhibit the stimulatory effect of MCH on LH release, also inhibited the effect of leptin. We propose that one route by which leptin may promote reproductive activity is by enhancing MCH release from fibres within the mPOA. Speculative mechanisms for the action of MCH include the following possibilities: MCH may be acting on the specific MCH receptor which in turn interacts with a melanocortin or melanocortin-like receptor; MCH may bind directly to one of the melanocortin receptors; or melanocortin antagonists may interact with the MCH receptor. [source] Effects of Prenatal Ethanol Exposure on Hypothalamic-Pituitary-Adrenal Function Across the Estrous CycleALCOHOLISM, Issue 6 2009Ni Lan Background:, Rats prenatally exposed to ethanol (E) typically show increased hypothalamic-pituitary-adrenal (HPA) responses to stressors in adulthood. Importantly, prenatal ethanol may differentially alter stress responsiveness in male and female offspring, suggesting a role for the gonadal hormones in mediating the effects of ethanol on HPA activity. We investigated the role of ethanol-induced changes in hypothalamic-pituitary-gonadal (HPG) activity in the differential HPA regulation observed in E compared to control females across the estrous cycle. Methods:, Peripheral hormones and changes in central neuropeptide mRNA levels were measured across the estrous cycle in adult female offspring from E, pair-fed (PF) and ad libitum-fed control (C) dams. Results:, Ethanol females showed normal estrous cyclicity (vaginal smears) but delayed sexual maturation (vaginal opening). Both HPG and HPA activity were differentially altered in E (and in some cases, PF) compared to control females as a function of estrous cycle stage. In relation to HPG activity, E and PF females had higher basal and stress estradiol (E2) levels in proestrus compared to other phases of the cycle, and decreased GnRH mRNA levels compared to C females in diestrus. Further, E females had greater variation in LH than PF and C females across the cycle, and in proestrus, only E females showed a significant LH increase following stress. In relation to HPA activity, both basal and stress CORT levels and overall ACTH levels were greater in E than in C females in proestrus. Furthermore, AVP mRNA levels were increased overall in E compared to PF and C females. Conclusions:, These data demonstrate ethanol-induced changes in both HPG and HPA activity that are estrous phase-specific, and support the possibility that changes in HPA activity in E females may reflect differential sensitivity to ovarian steroids. E females appear to have an increased HPA sensitivity to E2, and a possible shift toward AVP regulation of HPA activity. That PF were similar to E females on some measures suggests that nutritional effects of diet or food restriction played a role in mediating at least some of the changes observed. [source] Identification and gene expression profiling of the Pum1 and Pum2 members of the Pumilio family in the chickenMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2008Jee Young Lee Abstract Members of the Pumilio (Pum) family of RNA-binding proteins act as translational repressors and are required for germ cell development and asymmetric division. We identified the chicken Pum1 and Pum2 genes and analyzed their expression patterns in various tissues. Comparative sequence analysis of the Pum1 and Pum2 proteins from the drosophila, chicken, mouse, and human revealed a high degree of evolutionary conservation in terms of the levels of homology of the peptide sequences and the structure of Pumilio homology domain (PUM-HD), C-terminal RNA-binding domain, with similar spacing between the adjacent Pum eight tandem repeats. In addition, phylogenetic patterns of pumilio family showed that Pum 1 and 2 of chicken are more closely related to those of mouse and human than other species and Pum1 is more conserved than Pum2. Using real-time RT-PCR, the expression levels of the Pum1 and Pum2 genes were found to be highest in hatched female gonads, and high-level expression of Pum2 was detected in 12-day and hatched gonads among the various chicken embryonic tissues tested. In adult tissues, the expression levels of Pum1 and Pum2 were expressed at higher levels in the testis and muscle than in any other tissue. The characteristics of the tissue-specific expression of Pum genes suggest that Pum1 and Pum2 have effects crucially in particular stage during development of chicken gonads depending on sexual maturation. Mol. Reprod. Dev. 75: 184,190, 2008. © 2007 Wiley-Liss, Inc. [source] Endocrine mechanisms of primate life history trade-offs: Growth and reproductive maturation in vervet monkeysAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2009Patricia L. Whitten Life history theory predicts that the timing of maturation will result from a trade-off between growth and the age of first reproduction. This trade-off and its mechanisms of action are still poorly understood in many species and have not been well studied at the individual level. This study examined hypothesized trade-offs between growth and reproductive maturation in wild populations of vervet monkeys (Cercopithecus aethiops) from Kenya, East Africa. Individuals were sampled from four populations in widely separated sites differing in temperature, altitude, and rainfall. Biological samples and morphometric measures were collected from 50 adult males, 83 adult females, and 225 juveniles. Gonadal steroids and leptin levels were analyzed by radioimmunoassay of sera from 136 juvenile males and 90 juvenile females. Cross-sectional profiles of morphometric and endocrine data were used to assess the onset and cessation of growth in relation to sexual maturation. Gonadal steroids were used to assess sexual maturation and breeding onset. Leptin was used as an index of nutritional state. Estimates of mortality were derived from population age-structure. Across populations, higher resource productivity and nutrient status were associated with more rapid growth. Shorter growth duration was associated with earlier reproductive onset. These findings provide support for models of trade-offs between the timing of growth completion and reproductive onset, but they are contradicted by the evidence that reproduction precedes the cessation of growth in these populations. The biphasic actions of estradiol provide an alternative model and mechanism for the growth-reproduction trade-off. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] The influence of sexual maturation on blood pressure and body fatness in African-American adolescent girls and boysAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2009Xiaoli Chen To examine the influence of sexual maturation (SM) on blood pressure (BP) and body fatness during puberty among African-American children. Longitudinal data were collected from 283 African-American children aged 9,15 years over a 1.5-year period. Measured anthropometric measures included height, weight, skinfold thickness, waist circumference (WC), and systolic and diastolic BP (SBP/DBP) at baseline, 1-year, and 1.5-year follow-up were used. SM was assessed using self-reported Tanner stages (range 1,5) at baseline. Spearman correlation and regression analyses were conducted to test associations between study variables. Early maturing girls had higher BP and body mass index (BMI = weight (kg)/height (m)2) at follow-up than nonearly maturing girls (SBP: 117.4 vs. 111.7; DBP: 66.3 vs. 60.7; BMI: 27.7 vs. 23.5; all P < 0.05, respectively). Baseline Tanner stage was positively associated with follow-up SBP (r = 0.28), DBP (r = 0.37), BMI (r = 0.45), skinfold thickness (r = 0.37), and WC (r = 0.40) in girls, but not in boys. The influence of SM on BP independent of body size was tested via several different multiple linear regression models by adding measures of body size and their changes (height and BMI) between baseline and follow-up. Early maturing girls had higher SBP and DBP (, = 4.30, P < 0.05; , = 3.28, P < 0.05; respectively) and BMI (, = 1.69, P < 0.05) at 1.5-year follow-up than their counterparts. In boys, a marginally significant reverse association (, = ,1.05 to ,1.19) between SM stages and DBP was detected. SM affects BP and body fatness in girls, and should be considered in assessment of BP and obesity in adolescents. Am. J. Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source] Pheromones in relation to aggregation and reproduction in desert locustsPHYSIOLOGICAL ENTOMOLOGY, Issue 1 2003Hans-Jörg Ferenz Abstract. Desert locusts, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), exhibit a population density-dependent phase polymorphism which includes the gradual change of many morphological, physiological and behavioural characteristics. Many volatiles associated with desert locusts have been identified recently and it is assumed that they are involved in pheromonal control of behaviour and development of locusts. Ovipositing females deposit with their egg pods several volatiles that appear to be attractive to other females resulting , possibly in combination with environmental factors , in an aggregated oviposition. Mature males release several volatiles, among them phenylacetonitrile, which are reported to accelerate sexual maturation in young males. Also, aggregation pheromone systems for hoppers and adults have been described. However, recent studies and publications shed a new light on the postulated effects of some of these volatiles. Gregarious behaviour can undoubtedly be induced by mechanical stimuli. Furthermore, the main component of the adult aggregation pheromone system, phenylacetonitrile, is found to be a repellent obviously not involved in aggregation. Comprehensive studies have demonstrated that phenylacetonitrile is used by mature gregarious males as a courtship inhibition pheromone to enhance mate guarding. Recent progress, contradictory results and perspectives in desert locust pheromone research related to reproduction are summarized and discussed in this paper. [source] The biosynthesis of Juvenile Hormone, its degradation and titres in females of the true armyworm: a comparison of migratory and non-migratory populationsPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2000Jeremy N. McNeil Summary In a previous study [McNeil et al. (1996) Archives of Insect Biochemistry and Physiology, 32, 575,584], patterns of sexual maturation and Juvenile Hormone (JH) biosynthesis were compared in virgin females from migratory (North American) and non-migratory (Azorean) populations of the true armyworm moth, Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae). Sexual maturation occurred at a significantly earlier age after emergence in the non-migrant population, and the rates of biosynthesis of JH in vitro suggested that lower titres of JH may be required to initiate the onset of calling behaviour (pheromone emission) and ovarian development in Azorean females. To examine the physiological differences in the reproductive biology of migratory and non-migratory populations in greater detail, the haemolymph titres of JH and JH esterase activity were compared in virgin females as a function of age. In addition, the effects of mating on JH biosynthesis in vitro, JH titres, JH esterase activity and egg production were measured in the two populations. As expected, JH titres rose more rapidly after emergence in Azorean females than in their North American counterparts but, contrary to our prediction, the maximum levels were also higher in the non-migrant population. Activity of JH esterase was much higher in Azorean females on the day of emergence. However, by the second day both populations had similar activity levels (about 17 nmol JH/min/ml) and exhibited a similar age-related decline in subsequent days. Mating did not affect the rate of JH biosynthesis in vitro but resulted in a significant increase in the titres of JH in the haemolymph of both populations. The maximum titre (a five-fold increase) occurred within 24 h of mating in Azorean females. In North American individuals the increase was greater (seven-fold) but did not occur until 48 h after mating. No difference in the activity of JH esterase was observed between mated and virgin North American females. By contrast, while there was an age-related decline in the activity of JH esterase in mated Azorean females, as seen in both North American groups, activity levels in virgin females remained constant with age. In all females, mating resulted in a significant increase in egg production within 24 h. The Azores is a volcanic archipelago, so these non-migratory populations were probably founded by immigrants originating from migratory continental populations. It is clear from our results that the change from a life history that includes migration to a non-migratory one involved more than just a temporal shift in the timing of the production of JH. Furthermore, the interpopulation differences in titres of JH and mating-induced changes reported here cannot be fully explained by the observed differences in the patterns of activity of JH esterase and JH biosynthesis in vitro. [source] Degeneration and regeneration of ultraviolet cone photoreceptors during development in rainbow troutTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2006W. Ted Allison Abstract Ultraviolet-sensitive (UVS) cones disappear from the retina of salmonid fishes during a metamorphosis that prepares them for deeper/marine waters. UVS cones subsequently reappear in the retina near sexual maturation and the return migration to natal streams. Cellular mechanisms of this UVS cone ontogeny were investigated using electroretinograms, in situ hybridization, and immunohistochemistry against opsins during and after thyroid hormone (TH) treatments of rainbow trout (Oncorhynchus mykiss). Increasing TH levels led to UVS cone degeneration. Labeling demonstrated that UVS cone degeneration occurs via programmed cell death and caspase inhibitors can inhibit this death. After the cessation of TH treatment, UVS cones regenerated in the retina. Bromodeoxyuridine (BrdU) was applied after the termination of TH treatment and was detected in the nuclei of cells expressing UVS opsin. BrdU was found in UVS cones but not other cone types. The most parsimonious explanation for the data is that UVS cones degenerated and UVS cones were regenerated from intrinsic retinal progenitor cells. Regenerating UVS cones were functionally integrated such that they were able to elicit electrical responses from second-order neurons. This is the first report of cones regenerating during natural development. Both the death and regeneration of cones in retinae represent novel mechanisms for tuning visual systems to new visual tasks or environments. J. Comp. Neurol. 499:702,715, 2006. © 2006 Wiley-Liss, Inc. [source] Is Tryptophan ,more' Essential than Other Essential Aminoacids in Development?ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2009A Morphologic Study Summary An ontogenetic study was designed on developing rats in uterus of mothers tryptophan deprived at day 1 (exp. 1) and day 14.5 (exp. 2) of conception to verify the supposed determining role of the serotoninergic system (SS) in sexual differentiation in mammals. Tryptophan-free feeding was pursued uninterruptedly in the litter after birth, during lactation and post-natal development. Tryptophan-free pregnant rats were obtained by exclusion of tryptophan sources from chow. In both exp. 1 and exp. 2, the litter showed at birth a significant physical under evolution that worsened, during post-natal development, to a much more marked dwarfism in exp. 1 pups. Growth hormone concentrations in both sexes of dwarf rats were lower than that in the control rats. At 30 days post-natal age, whereas exp. 1 female rats showed a right-timed onset of puberty, no descensus of testes could be observed in male rats of same experiment. Dwarf male rats showed an evident hypotrophy of the whole reproductive apparatus. In histological examination of testes, neither spermatogenesis nor Leydig cells have been observed. Moreover, dwarf female rats showed a pronounced hypotrophy of reproductive organs, but a normal puberal status pattern was evident. In exp. 2, litters showed a less pronounced dwarfism, but a normal right-timed onset of puberty in both male and female rats. Data indicate that role of tryptophan in physical and sexual maturation in both male and female rats is essential. [source] CHARGE syndrome as unusual cause of hypogonadism: endocrine and molecular evaluationANDROLOGIA, Issue 5 2010L. Foppiani Summary Coloboma, heart defect, atresia choanae, retarded growth and development, genital hypoplasia, ear anomalies (CHARGE) syndrome is a genetic syndrome in which hypogonadism is a frequent feature. A causative mutation within the chromodomain helicase DNA-binding protein-7 gene, which plays an important role in the embryonic development, is present in 2/3 of affected patients. We describe the clinical, hormonal and molecular characteristics of a young man from Ecuador who was diagnosed as having CHARGE syndrome at an adult age. The patient showed several phenotypic features of the syndrome, associated with a prepubertal state and cryptorchidism; hypogonadotrophic hypogonadism with undetectable testosterone levels not responsive to hCG testing and severe osteoporosis were ascertained. Molecular evaluation of the CHD7 gene showed the novel frameshift truncating heterozygous mutation p.Tyr1046Glyfs*23 in exon 12. Magnetic resonance imaging revealed mild hypoplasia of the pituitary gland and hypoplasia of the posterior cranial fossa. Parenteral testosterone therapy led to sexual development over time and, in combination with diphophonate therapy and calcium,vitamin D supplementation, significantly improved bone mineralisation. Early proper hormonal treatment of hypogonadism in patients with complex genetic syndromes is important to achieve normal sexual maturation, improve quality of life and avoid significant comorbidities, such as osteoporosis. [source] The use of continuous light to suppress pre-harvest sexual maturation in sea-reared Atlantic salmon (Salmo salar L.) can be reduced to a 4-month windowAQUACULTURE RESEARCH, Issue 10 2010Eric Leclercq First page of article [source] Effects of transplants and extracts of thoracic nerve cord,ganglia on gonad maturation of penaeoid shrimpAQUACULTURE RESEARCH, Issue 2 2010Jorge Alfaro Abstract It has been established recently that interspecific and intraspecific thoracic ganglia transplants from Penaeidae are gradually absorbed by the host without activating an encapsulation mechanism. Therefore, this research was designed to evaluate the thoracic ganglia extracts and implants from maturing Trachypenaeus byrdi (Burkenroad), Xiphopenaeus riveti (Bouvier) and Penaeus (Litopenaeus) occidentalis (Streets) females as potential inducers of sexual maturation in Penaeus (Litopenaeus) stylirostris (Stimpson), Penaeus (Litopenaeus) vannamei (Boone) and T. byrdi, from the Gulf of Nicoya, Costa Rica. Our findings suggest that interspecific and intraspecific thoracic ganglia extracts or implants from maturing penaeoid females are not capable of inducing a clear response in sexual maturation in males or females. Tissues were tested at increasing doses from 137, 386, 525 and 1500 ,g g,1 body weight, without any positive response. It is proposed that a hypothetical hormone, vitellogenesis-stimulating hormone, from the thoracic ganglia, is under the strong negative control of eyestalks, by the gonad-inhibiting hormone in the subgenus Litopenaeus. Therefore, the use of thoracic ganglia extracts or implants would be ineffective when compared with injecting serotonin alone, as the present results seem to support. [source] Reduced sexual maturation in male post-smolt 1+ Atlantic salmon (Salmo salar L.) by dietary tetradecylthioacetic acidAQUACULTURE RESEARCH, Issue 5 2009Henriette Alne Abstract In the present study, the possible effect of dietary treatment on early sexual maturation in post-smolt Atlantic salmon, without any negative effect regarding growth, was investigated. The experiment was performed using 4400 individually marked (Pit tag) 1+ salmon, fed either a control diet or a diet supplemented with 0.5% tetradecylthioacetic acid (TTA) in duplicates for 3, 6 or 12 weeks after sea transfer. Compared with the control, dietary supplementation of TTA resulted in a threefold reduction in incidence of sexual mature males (0.6% vs. 1.8%). A curve-linear relationship between relative reduction in maturation and weeks of feeding TTA was found, indicating that the effect is most marked as a result of the first weeks of feeding and then levelling off. No negative dietary impact on growth was observed. As the level of fat in the muscle was reduced by dietary TTA, it seems that post-smolt supplemented dietary TTA do not accumulate high enough energy stores to start the maturation process, whereas the energy-enhancing effect of TTA due to increased fatty acid oxidation capacity may maintain the growth potential. Compared with immature salmon, sexually maturing fish revealed increased spring growth before the onset of maturation. [source] Growth and reproductive performance of triploid and diploid blacklip abalone, Haliotis rubra (Leach, 1814)AQUACULTURE RESEARCH, Issue 2 2009Wenshan Liu Abstract Growth and reproduction of triploid and diploid blacklip abalone Haliotis rubra (Leach, 1814) were compared in a 30-month study. Triploidy was induced by inhibition of the second polar body formation using 6-dimethylaminopurine (6-DMAP) or cytochalasin B (CB). There were no significant differences in growth and survivorship between triploid and diploid abalone. However, triploid abalone had a more elongated shell and greater foot muscles than diploid abalone. A slightly curvilinear growth in shell length was conformed to all treatments. While diploid abalone had reached sexual maturity and spawned during the study, gonadal development and gamete maturation were abnormal in triploids. Female triploids lacked an apparent gonad at the macroscopic level but microscopic examination revealed that they had a thin layer of oogonia development. In contrast, male triploids were able to form similar-sized gonads to diploids during most of the reproductive period, but with brown-yellow discolouration and stalled gametogenesis at spermatocyte formation. Sex ratio of triploid abalone did not deviate from 1:1. With the onset of sexual maturation, growth and gonadal maturation occurred concurrently in diploid abalone, and there was no indication that growth of (diploid) abalone was reduced. [source] | ||||||||||||||||