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Reproductive Cycle (reproductive + cycle)
Kinds of Reproductive Cycle Selected AbstractsIntestinal Calcium Transporter Genes Are Upregulated by Estrogens and the Reproductive Cycle Through Vitamin D Receptor-Independent Mechanisms,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2003SJ Van Cromphaut Abstract 1,,25(OH)2 -vitamin D strongly regulates the expression of the epithelial calcium channel CaT1. CaT1 expression is reduced in ERKO, mice and induced by estrogen treatment, pregnancy, or lactation in VDR WT and KO mice. Estrogens and vitamin D are thus independent potent regulators of the expression of this calcium influx mechanism, which is involved in active intestinal calcium absorption. Introduction: Active duodenal calcium absorption consists of three major steps: calcium influx into, transfer through, and extrusion out of the enterocyte. These steps are carried out by the calcium transport protein 1 (CaT1), calbindin-D9K, and the plasma membrane calcium ATPase (PMCA1b), respectively. We investigated whether estrogens or hormonal changes during the female reproductive cycle influence the expression of these genes, and if so, whether these effects are vitamin D-vitamin D receptor (VDR) dependent. Materials and Methods: We evaluated duodenal expression patterns in estrogen receptor (ER), and -, knockout (KO) mice, as well as in ovariectomized, estrogen-treated, pregnant, and lactating VDR wild-type (WT) and VDR KO mice. Results: Expression of calcium transporter genes was not altered in ERKO, mice. CaT1 mRNA expression was reduced by 55% in ERKO, mice, while the two other calcium transporter genes were not affected. Ovariectomy caused no change in duodenal expression pattern of VDR WT and KO mice, whereas treatment with a pharmacologic dose of estrogens induced CaT1 mRNA expression in VDR WT (4-fold) and KO (8-fold) mice. Pregnancy enhanced CaT1 expression equally in VDR WT and KO mice (12-fold). Calbindin-D9K and PMCA1b expression increased to a lesser extent and solely in pregnant VDR WT animals. In lactating VDR WT and KO mice, CaT1 mRNA expression increased 13 times, which was associated with a smaller increase in calbindin-D9K protein content and PMCA1b mRNA expression. Conclusions: Estrogens or hormonal changes during pregnancy or lactation have distinct, vitamin D-independent effects at the genomic level on active duodenal calcium absorption mechanisms, mainly through a major upregulation of the calcium influx channel CaT1. The estrogen effects seem to be mediated solely by ER,. [source] Morphological and Morphometric Changes of Pituitary Lactotrophs of Viscacha (Lagostomus maximus maximus) in Relation to Reproductive Cycle, Age, and SexTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2010Verónica Filippa Abstract Lactotrophs in pituitary pars distalis (PD) of viscacha were studied by immunohistochemistry and morphometric analysis in the following groups: 1) adult males throughout the reproductive cycle (reproductive, gonadal regression, and recovery periods), 2) melatonin-treated adults, 3) castrated adults, 4) prepubertal, 5) non-pregnant females, and 6) pregnant females (early, mid, and late pregnancy). Immunopositive percentage area (%IA), cell percentage in PD (% PDC), number of cells per reference area (no.cell/RA), major cellular and nuclear diameters were analyzed. Lactotrophs were mainly localized in the ventro,medial region and the caudal extreme of PD. In the male viscachas, they were isolated in small and big groups, close to blood vessels and near follicles. These cells were pleomorphic and with a heterogeneous cytoplasmic immunolabeling pattern. In the adult males of the gonadal regression period the morphometric parameters were the lowest. Most parameters of lactotrophs in the prepubertal were significantly lower than in the adult males in the reproductive period. In the melatonin-treated animals and in castrated animals there was a decrease in %IA, %PDC, and no.cell/RA. In the females, the morphometric parameters increased at the end of pregnancy. Non-pregnant females exhibited a higher immunopositive area and number, but a smaller size of cells than males. Our results showed that in the adult male viscacha, lactotrophs vary seasonally, probably due to the photoperiod effect through melatonin. Besides the changes observed after castration, in prepubertal animals, in adults of different sex, and during pregnancy suggest that the gonadal steroid hormones might modify the lactotrophs activity. Anat Rec, 293:150,161, 2010. © 2010 Wiley-Liss, Inc. [source] Reproductive cycle of female Brazilian codling, Urophycis brasiliensis (Kaup 1858), caught off the Uruguayan coastJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2000By A. Acuña Between August 1993 and September 1995, aspects of reproduction of female Urophycis brasiliensis (Phycidae), a euryhaline species found in the Western Atlantic between 23° and 40° S, were studied. A total of 2500 specimens (23,60 cm; 113,2400 g) were obtained from artisanal fishermen at two locations on the Uruguayan coast: Piriápolis, influenced by the discharge of the Río de la Plata, and La Paloma, a marine site. The ovaries of 900 fish, analysed according to standard histological techniques, revealed eight maturity stages, including one virgin ovary obtained from the catch of a research vessel. The gonadosomatic index ranged from 0.13 to 8.7. Its maximum was determined in the autumn in La Paloma, whereas a shift towards the winter was observed in Piriápolis. In both capture areas, resting stage 2 was present in the samples throughout the year, reaching 67% of the total. At no time were hydrated ovaries observed. The histological cycle is described and compared with macroscopic features of the female gonad. Maturity stages determined in the field had to be confirmed by histological analysis in order to avoid erroneous classification. Although the two ports are only 150 km apart, data indicate different and extended reproductive periods, between June and December for Piriápolis, and March to May for La Paloma. Data indicate synchronous group spawning, possibly as a reproductive strategy in a highly variable environment. The results are compared with scarce information available on U. brasiliensis in its distribution area and data on other species of the same genus. [source] Reproductive cycle and sex inversion in razor fish, a protogynous labrid in the southern Mediterranean SeaJOURNAL OF FISH BIOLOGY, Issue 6 2004G. Candi The reproductive biology of the Mediterranean razor fish Xyrichthys novacula was investigated by demographic data and histological analysis of the female, intersexual and male gonads. Specimens were collected by bottom trawl on a monthly basis between June 2000 and July 2001 in a sandy bay in southern Thyrrenian. Gonad histology confirmed that the Mediterranean razor fish is a monandric, protogynous hermaphrodite. Females reached first sexual maturity at 100 mm (LT) and the estimated mean LT at first maturity (L50) was 125 mm. Females exhibited asynchronous ovarian development and multiple ovulations occurred over the spawning period. Vitellogenesis started in early May and spawning occurred from late May until late September. Sexual transition involved a large-scale atresia of all oocyte stages and a massive degeneration of ovarian tissue followed by primordial germ cells proliferation. Sex change began at spawning time (June) but transitional individuals tended to cluster at the end of the reproductive period (September). They accounted for 17·1% of the population sampled and were found in a broad size range (105,150 mm LT). [source] Seasonal evaluation of reproductive status and exposure to environmental estrogens in hornyhead turbot at the municipal wastewater outfall of Orange County, CAENVIRONMENTAL TOXICOLOGY, Issue 5 2007Xin Deng Abstract Seasonal changes in developmental stages, condition factor (CF), gonadosomatic index, and plasma vitellogenin (Vtg) concentrations in male and female hornyhead turbot were examined at the wastewater outfall (T1) of the Orange County Sanitation District, and two farfield sites T11 (7.7 km northwest of the outfall) and Dana Point (35 km south of the outfall) between February 2005 and May 2006. Fish collected from the three sites exhibited male-oriented sex ratios. With few exceptions, developmental stages, CF, and GSI of both genders and plasma Vtg concentrations of females were not significantly different in samples collected from different sites at the same sampling period. More advanced gonad developmental stages and higher plasma Vtg concentrations in females were observed in August, indicating the seasonality of the reproductive cycle for this species. Plasma Vtg concentrations in males were observed in all of the sampling sites with the highest prevalence at T11 relative to T1 and Dana Point. The Vtg expression in males from the three sampling sites indicated widespread exposure to estrogenic compounds in waters of coastal California. However, the histopathological and reproductive relevance of the responses appeared to be insignificant and may not affect the population in these locations. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 464,471, 2007. [source] Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft-shell clam, Mya arenariaENVIRONMENTAL TOXICOLOGY, Issue 3 2002C. Blaise Abstract A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the St. Lawrence River estuary (Quebec, Canada) was undertaken to study the possible effects of anthropogenic contaminant input on soft-shell clam (Mya arenaria) populations. Bivalve sampling sites were selected because they reflected a range of areas representative of either no known (or apparent) pollution sources or of areas potentially influenced by different gradients and types of contamination sources. The most upstream site selected in the Saguenay Fjord, nearest to a highly populated and industrialized sector, and the most downstream site, near its mouth with the St. Lawrence River estuary, spanned a distance of some 70 km and encompassed the entire intertidal area suitable for Mya arenaria habitat. To measure effects in collected animals, we used a comprehensive battery of biomarkers composed of metallothionein-like proteins (MT), 7-ethoxyresorufin O-deethylase activity (EROD), DNA damage (DD), lipid peroxidation (LPO), vitellinlike proteins (Vn), phagocytosis (PHAG), nonspecific esterase (NspE) activity, and condition factor (weight-to-length ratio of clams). Vn, PHAG, DD, and NspE biomarkers were assayed in hemolymph (or hemocytes), whereas others (MT, EROD, LPO) were determined in the digestive gland. Whole-tissue metal content was also quantified in clams collected in the spatial survey. The spatial survey conducted in June 1997 showed significant effects at all sites, and principal component analysis indicated in addition that the more important responses were linked to the MT, LPO, and NspE biomarkers. Clams collected from sites closest to the upstream reaches of the fjord generally displayed higher levels of tissue metals (cadmium, manganese), as well as greater responses of NspE activity, MT, LPO, and PHAG. Animals collected from sites influenced by municipal wastewaters had higher levels of Vn, suggesting the presence of environmental estrogens. The results of the temporal survey (six monthly samplings of clams at three sites from May through October, 1997) showed that the bivalve reproductive cycle (vitellogenesis and spawning) can modulate the expression of several biomarkers. Vn levels, for example, were positively correlated with DD and EROD and negatively correlated with MT, suggesting that reproduction can influence the susceptibility of clams to some contaminants. Discrimination analysis over the 6 months of sampling revealed that the mean value of the discriminant function changed significantly over time, suggesting important changes in the relative contribution of each biomarker. In short, this study has provided evidence that clam populations in the Saguenay Fjord are impacted by multiple sources of contamination whose effects can be modulated by reproduction. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 170,186, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10048 [source] Do Male Veiled Chameleons, Chamaeleo calyptratus, Adjust their Courtship Displays in Response to Female Reproductive Status?ETHOLOGY, Issue 6 2002Erin C. Kelso Variation in male courtship behavior may be due to inherent differences among males or may arise from males adjusting their courtship displays according to female responsiveness. Female veiled chameleons, Chamaeleo calyptratus, exhibit two distinctive suites of body coloration and behavior patterns that vary according to receptive and non-receptive stages of their reproductive cycle. We presented male chameleons with both receptive and non-receptive females, and recorded differences in their mating frequency, courtship intensity and courtship behavior patterns. As expected, males were more likely to court and attempt mating with receptive females. Although fewer males courted non-receptive females, their courtship displays were significantly longer than those directed towards receptive females. Males also adjusted the contents of their displays according to female reproductive condition. Certain behavior patterns were unique to courtship displays directed towards each class of females. Males exhibited the behavior pattern `head roll' only when paired with receptive females, and `chin rub' was displayed only during courtship of non-receptive females. We hypothesize that these differences in male courtship frequency, intensity and content reflect differences in female reproductive value. Although males may benefit from mating with both receptive and non-receptive females, the costs associated with courtship may depend on female responsiveness. Thus, males adjust their courtship tactics accordingly. [source] Effects of oestrogen replacement therapy on pattern reversal visual evoked potentialsEUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2000H. Yilmaz As a result of a regression in the ovarian functions, oestrogen level in circulation during the menopause drops to 1/50 of its value in the normal reproductive cycle. Excitatory oestrogen increases the sensitivity of the central nervous system to catecholamines by changing the opening frequency of voltage-related L-type calcium channels and augmenting the effect of glutamate; in addition it inhibits the formation of gamma-amino butyric acid (GABA) by the inhibition of glutamate decarboxylase enzyme. It is argued that oestrogen increases transmission in the optic pathways and that oestrogen is responsible for the shorter latency values and higher amplitudes of visual evoked potentials in women. We recorded the monocular pattern reversal visual evoked potentials (PRVEP) of both eyes of 54 post-menopausal women before treatment and of 30 of them after replacement therapy with Tibolon, and of 24 women receiving placebo treatment. The explicit values of P100 latency of right and left eyes before treatment were 98.8 ± 3.5 and 99.0 ± 3.3 ms, respectively. The explicit values of P100 latency of right and left eyes after placebo treatment were 98.6 ± 3.7 and 98.8 ± 4.0, respectively. The explicit values of P100 latency of right and left eyes after replacement treatment were 94.6 ± 3.7 and 94.8 ± 4.0, respectively. We found a statistically significant decrease in the mean PRVEP latencies and a statistically significant increase in mean amplitudes after replacement treatment (P < 0.001) compared with those before treatment and those after placebo treatment. We attributed the changes in PRVEP values after replacement treatment to the action of Tibolon, which acted as a natural sex steroid and speeded the visual transmission time via the widespread receptors in the central nervous system. It is concluded that PRVEP is an objective electrophysiological assessment method in evaluating the efficiency of hormone replacement therapy in post-menopausal women. [source] Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause IIIGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2009Article first published online: 22 JAN 200 Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause III. The embryo, surrounded by a transparent vitelline envelope, is in the pre-hatching stage. A prominent eye and part of the pigmented body and tail are apparent. Why annual fishes? Annual fishes (Order Cyprinodontiformes) are a special kind of teleost, found in Africa and South America, with developmental strategies closely related to their life cycle. These fishes inhabit temporary pools that undergo drying during summer, when all adults die. The embryos remain buried in the bottom mud and are resistant to desiccation. In the subsequent rainy season they hatch a few hours after the pool is flooded and a new reproductive cycle begins. This developmental pattern is characterized by the presence of a unique stage between cleavage and embryogenesis, dispersion-aggregation of blastomeres and because the embryos show reversible developmental arrests (diapauses) at different stages. Annual fish embryos are transparent, large, hardy and easy to maintain in the laboratory. Adults show continuous production of eggs and juveniles reach sexual maturity a few weeks after hatching (an unusual condition in fishes). Their particular developmental features confer unique opportunities for research on cell behavior during early development, the effect of environmental factors on development, the regulation of diapauses and the mechanisms involved in sex determination, among others topics. Image provided by Nibia Berois, Universidad de la República, Montevideo, Uruguay. [source] Estimation of gonad volume, fecundity, and reproductive stage of shovelnose sturgeon using sonography and endoscopy with application to the endangered pallid sturgeonJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007By J. L. Bryan Summary Most species of sturgeon are declining in the Mississippi River Basin of North America including pallid (Scaphirhynchus albus F. and R.) and shovelnose sturgeons (S. platorynchus R.). Understanding the reproductive cycle of sturgeon in the Mississippi River Basin is important in evaluating the status and viability of sturgeon populations. We used non-invasive, non-lethal methods for examining internal reproductive organs of shovelnose and pallid sturgeon. We used an ultrasound to measure egg diameter, fecundity, and gonad volume; endoscope was used to visually examine the gonad. We found the ultrasound to accurately measure the gonad volume, but it underestimated egg diameter by 52%. After correcting for the measurement error, the ultrasound accurately measured the gonad volume but it was higher than the true gonad volume for stages I and II. The ultrasound underestimated the fecundity of shovelnose sturgeon by 5%. The ultrasound fecundity was lower than the true fecundity for stage III and during August. Using the endoscope, we viewed seven different egg color categories. Using a model selection procedure, the presence of four egg categories correctly predicted the reproductive stage ± one reproductive stage of shovelnose sturgeon 95% of the time. For pallid sturgeon, the ultrasound overestimated the density of eggs by 49% and the endoscope was able to view eggs in 50% of the pallid sturgeon. Individually, the ultrasound and endoscope can be used to assess certain reproductive characteristics in sturgeon. The use of both methods at the same time can be complementary depending on the parameter measured. These methods can be used to track gonad characteristics, including measuring Gonadosomatic Index in individuals and/or populations through time, which can be very useful when associating gonad characteristics with environmental spawning triggers or with repeated examinations of individual fish throughout the reproductive cycle. [source] Seasonal reproductive cycle of pike, Esox lucius L., from the River DanubeJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2002M. Lenhardt Seasonal changes in ovaries and testes of the pike, sampled in the Danube (at 1163 and 1175 km) were analysed in this research. According to the presence of developing and resting oocytes in histological sections of pike ovaries sampled during August, it is possible to determine which female will be sexually mature the following spring. Active vitellogenesis starts in September (with oocyte diameters of 514 ± 54 ,m and 453 ± 68 ,m, at the upstream and downstream locality, respectively), at which time the differences between the developing and resting oocytes are even more obvious. Active spermatogenesis starts in September and lasts for 2 months, and by November primarily spermatozoa can be seen in histological sections. The reproductive score points to differences in samples from the two localities that can be explained by the differing characteristics of the habitat. Values of absolute fecundity (AF) ranged from 524 to 123 896 eggs, and the mean value of relative fecundity (RF) was 40.4 ± 12.5. [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] Intestinal Calcium Transporter Genes Are Upregulated by Estrogens and the Reproductive Cycle Through Vitamin D Receptor-Independent Mechanisms,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2003SJ Van Cromphaut Abstract 1,,25(OH)2 -vitamin D strongly regulates the expression of the epithelial calcium channel CaT1. CaT1 expression is reduced in ERKO, mice and induced by estrogen treatment, pregnancy, or lactation in VDR WT and KO mice. Estrogens and vitamin D are thus independent potent regulators of the expression of this calcium influx mechanism, which is involved in active intestinal calcium absorption. Introduction: Active duodenal calcium absorption consists of three major steps: calcium influx into, transfer through, and extrusion out of the enterocyte. These steps are carried out by the calcium transport protein 1 (CaT1), calbindin-D9K, and the plasma membrane calcium ATPase (PMCA1b), respectively. We investigated whether estrogens or hormonal changes during the female reproductive cycle influence the expression of these genes, and if so, whether these effects are vitamin D-vitamin D receptor (VDR) dependent. Materials and Methods: We evaluated duodenal expression patterns in estrogen receptor (ER), and -, knockout (KO) mice, as well as in ovariectomized, estrogen-treated, pregnant, and lactating VDR wild-type (WT) and VDR KO mice. Results: Expression of calcium transporter genes was not altered in ERKO, mice. CaT1 mRNA expression was reduced by 55% in ERKO, mice, while the two other calcium transporter genes were not affected. Ovariectomy caused no change in duodenal expression pattern of VDR WT and KO mice, whereas treatment with a pharmacologic dose of estrogens induced CaT1 mRNA expression in VDR WT (4-fold) and KO (8-fold) mice. Pregnancy enhanced CaT1 expression equally in VDR WT and KO mice (12-fold). Calbindin-D9K and PMCA1b expression increased to a lesser extent and solely in pregnant VDR WT animals. In lactating VDR WT and KO mice, CaT1 mRNA expression increased 13 times, which was associated with a smaller increase in calbindin-D9K protein content and PMCA1b mRNA expression. Conclusions: Estrogens or hormonal changes during pregnancy or lactation have distinct, vitamin D-independent effects at the genomic level on active duodenal calcium absorption mechanisms, mainly through a major upregulation of the calcium influx channel CaT1. The estrogen effects seem to be mediated solely by ER,. [source] Breeding biology of ostriches (Struthio camelus) in the Serengeti ecosystem, TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2009Flora J. Magige Abstract Ostrich breeding behaviour in the Serengeti ecosystem, Tanzania was investigated for differences in laying dates between low altitude western area (WA) and high altitude eastern area (EA) populations. Ostriches in WA laid eggs significantly earlier than in EA. The differences could be attributed to topography and rainfall pattern. Reliable rains in lower altitudes ensure availability of food that in turn influences the whole process of the reproductive cycle. Clutches were contributed by several females with a nest having up to 38 eggs. We also compared the frequency of observation of predators, ostriches, nests, ,singletons' (single eggs laid randomly) and broods between the two areas. There was no significant difference between WA and EA in 1) ostrich/nest ratio, indicating similar breeding densities; 2) ostrich/predator and predator/nest ratios, indicating that predation pressure was equally high; 3) nest/singleton and predator/singleton ratios, indicating that loss of nests did not vary between areas. However, there were significantly more predators, nests and ostriches compared to broods in EA than in WA, indicating a significantly lower reproductive success in EA. Using metapopulation terminology, ostriches in EA could be regarded as a ,sink' population and those in WA as a ,source' population, but investigations over longer time-periods are needed to further resolve if this is the case. Résumé Le comportement reproducteur des autruches dans l'écosystème du Serengeti, en Tanzanie, a étéétudié pour voir les différences dans les dates de pontes entre les populations de la zone occidentale (WA) à basse altitude et de la zone orientale (EA) à plus haute altitude. Les autruches de la WA pondent significativement plus tôt que celles de l'EA. Les différences peuvent être attribuées à la topographie et au régime de la pluviosité. Les pluies fiables à plus basse altitude garantissent la disponibilité de la nourriture, ce qui influence dès lors tout le processus du cycle reproducteur. Des couvées réunissaient les ,ufs de plusieurs femelles , un nid a eu jusqu'à 38 ,ufs. Nous avons aussi comparé la fréquence d'observations de prédateurs, d'autruches, de nids, de «ingletons» (des ,ufs solitaires pondus au hasard) et de nichées entre les deux zones. Il n'y a pas de différence significative entre WA et EA pour 1) le ratio autruches/nids, ce qui indique des densités de reproduction similaires; 2) le ratio autruches/prédateurs et le ratio prédateurs/nids, ce qui indique que la pression de la prédation est aussi haute des deux côtés; et 3) le ratio nids/singletons et le ratio prédateurs/singletons, ce qui indique que la perte des nids ne variait pas entre les zones. Cependant, il y avait significativement plus de prédateurs, de nids et d'autruches par rapport aux nichées dans l'EA que dans la WA, ce qui indique une réussite de la reproduction significativement plus faible dans la EA. En utilisant la terminologie de la métapopulation, les autruches de la EA peuvent être considérées comme une population «puits» et celles de la WA comme une population «source», mais il faudrait faire des recherches de plus longue durée pour montrer si c'est bien le cas. [source] Polyandry in coal tits Parus ater: fitness consequences of putting eggs into multiple genetic basketsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2007T. SCHMOLL Abstract Females of many species mate with multiple males within a single reproductive cycle. One hypothesis to explain polyandry postulates that females benefit from increasing within-brood genetic diversity. Two mechanisms may render sire genetic diversity beneficial for females, genetic bet-hedging vs. non-bet-hedging. We analysed whether females of the socially monogamous coal tit (Parus ater) benefit via either of these mechanisms when engaging in extra-pair (i.e. polyandrous) mating. To obtain a measure of within-brood genetic diversity as a function of paternal genetic contributions, we calculated a sire diversity index based on the established Shannon,Wiener Index. In 246 broods from two consecutive years, sire genetic diversity had no effect on either the mean or the variance in brood fitness measured as offspring recruitment within 4 years after birth. The hypothesis that benefits of increasing sire diversity contribute to selection for female extra-pair mating behaviour in P. ater was therefore not supported. [source] The link between migration, the reproductive cycle and condition of Sardinella aurita off Mauritania, north-west AfricaJOURNAL OF FISH BIOLOGY, Issue 5 2007R. Ter Hofstede The annual migration pattern of round sardinella Sardinella aurita up and down the north-western African coast between 12° N (Senegal) and 22° N (western Sahara) was shown to be associated with spawning activity and a distinct seasonality in fish condition, based on monthly sampling from commercial catches (2000,2003). Some S. aurita were found to spawn throughout the entire year, but a peak in spawning existed during the summer (June to September). The spawning cycle is apparent from seasonality in maturity stages, but is also demonstrated by the increase in gonad mass and fat content of the fish in springtime, the period preceding spawning. During the months after spawning, although feeding is maintained, the physical condition of the fish collapses, and fat content rapidly declines. [source] Effect of temperature changes on the reproductive cycle of roach in Lake Geneva from 1983 to 2001JOURNAL OF FISH BIOLOGY, Issue 2 2006C. Gillet In Lake Geneva, the surface water temperature has increased by 1° C over 20 years probably as a result of climate change. The effects of changes in temperature on the reproductive cycle of the roach Rutilus rutilus were assessed in a 19 year survey. Over time, spawning tended to begin earlier. The consequences of temperature changes were assessed on two different stages of the female reproductive cycle: the development of the ovaries from the beginning of autumn to ovulation, and the onset of the spawning period. The development of the ovaries was studied for 7 consecutive years from October to June. From 1 October to the onset of spawning, it was possible to assess the gonado-somatic index (IG) of females in terms of time expressed as a sum of degree-days. The correlation between IG and the sum of degree-days was +0·97. The onset of the roach spawning period in Lake Geneva was triggered by a thermal threshold (median and range 190 ± 10 degree-days for the 15 previous days). From October to April, climate warming accelerated the development of gonads, then in May, a thermal threshold that triggered the onset of roach spawning occurred earlier. [source] Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperatureJOURNAL OF FISH BIOLOGY, Issue 1 2005P. L. M. Van Dijk The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three-fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding. [source] Gonadotroph Heterogeneity, Density and Distribution, and Gonadotroph,Lactotroph Associations in the Pars Distalis of the Male Equine Pituitary GlandJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2004J. Townsend Abstract The intrapituitary mechanisms regulating gonadotrophin secretion in the horse remain unclear. Here, we examined seasonal and gonadal effects on the gonadotroph and lactotroph populations of male horses with the aim of defining a possible morphological basis for the differential release of gonadotrophins. Pituitaries were collected from: (i) gonadal-intact horses in the breeding season (GBS); (ii) orchidectomized horses in the breeding season (OBS); and (iii) orchidectomized horses in the nonbreeding season (ONBS). Immunohistochemistry was performed using antibodies to the luteinizing hormone (LH) , subunit, follicle-stimulating hormone (FSH) , subunit and prolactin. In all groups, gonadotrophs were distributed throughout the pars distalis, with dense populations detected near the borders with the pars tuberalis and pars intermedia. The numbers of LH-monohormonal, FSH-monohormonal and bihormonal cells/field were greater in GBS than in OBS and ONBS horses. Similarly, the proportion of gonadotrophs in relation to all pituitary cells was larger in gonadal-intact than orchidectomized horses. In the absence of the gonads, no effects of season were observed on these variables. Interestingly, the relative proportions of gonadotroph subtypes and the LH/FSH gonadotroph ratio were similar among groups. Furthermore, while specific gonadotroph,lactotroph associations were identified in all groups, significant gonadal effects within the breeding season and direct effects of season within orchidectomized horses were detected for the number of lactotrophs. This study reveals a gonadal-independent effect of season on the lactotroph, but not the gonadotroph population of the equine pituitary, and a clear gonadal stimulation of both cell types within the breeding season. We suggest that alterations in intercellular arrangements, rather than changes in the incidence of gonadotroph subtypes, may contribute to the differential release of gonadotrophins and, accordingly, to the intrapituitary control of fertility throughout the male equine annual reproductive cycle. [source] The Gonadotropin-Releasing Hormone Neurosecretory System of the Jerboa (Jaculus orientalis) and its Seasonal VariationsJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2000S. El Ouezzani Abstract The distribution of cells expressing gonadotropin-releasing hormone (GnRH) immunoreactivity was examined in the brain of adult jerboa during two distinct periods of the reproductive cycle. During spring,summer, when the jerboa is sexually active, a high density of cell bodies and fibres immunoreactive (IR) for GnRH was observed at the level of separation of the frontal lobes, in the medial septal nucleus (MS) and in the diagonal band of Broca (DBB), in the preoptic area (POA), in the organum vasculosum laminae terminalis (OVLT), in the retrochiasmatic area and hypothalamus. In autumn, when the jerboa is sexually inactive, GnRH-immunoreactivity was less intense than during spring,summer. In the POA, we noted a 55% decrease in the number of GnRH containing cells with no change in cell numbers in the MS-DBB. Furthermore, a lower density of GnRH immunopositive axon fibres is observed in all the previously mentioned structures and the immunoreaction intensity was very weak particularly within the median eminence and OVLT. Independently of the season, the GnRH immunoreactivity within neurones and fibres was similar in jerboas living in captivity and in jerboas living in their natural biotope. The effects of photoperiod on the density of POA-GnRH and arcuate nucleus ,-endorphin-containing cells were studied in jerboas maintained in long day [(LD) 16-h light, 8-h dark] and short day [(SD) 8-h light, 16-h dark] for 8 weeks. In the POA, the GnRH-IR cell number was not significantly altered by the photoperiod. Similarly, in the mediobasal hypothalamus, the number of ,-endorphin-IR neurones was not affected by such a parameter. Consequently, the GnRH seasonal variations cannot be correlated to changes in the photoperiod alone. [source] Anti-angiogenic drugs: from bench to clinical trialsMEDICINAL RESEARCH REVIEWS, Issue 4 2006Ana R. Quesada Abstract Angiogenesis, the generation of new capillaries through a process of pre-existing microvessel sprouting, is under stringent control and normally occurs only during embryonic and post-embryonic development, reproductive cycle, and wound repair. However, in many pathological conditions (solid tumor progression, metastasis, diabetic retinopathy, hemangioma, arthritis, psoriasis and atherosclerosis among others), the disease appears to be associated with persistent upregulated angiogenesis. The development of specific anti-angiogenic agents arises as an attractive therapeutic approach for the treatment of cancer and other angiogenesis-dependent diseases. The formation of new blood vessels is a complex multi-step process. Endothelial cells resting in the parent vessels are activated by an angiogenic signal and stimulated to synthesize and release degradative enzymes allowing endothelial cells to migrate, proliferate and finally differentiate to give rise to capillary tubules. Any of these steps may be a potential target for pharmacological intervention. In spite of the disappointing results obtained initially in clinical trials with anti-angiogenic drugs, recent reports with positive results in phases II and III trials encourage expectations in their therapeutic potential. This review discusses the current approaches for the discovery of new compounds that inhibit angiogenesis, with emphasis on the clinical developmental status of anti-angiogenic drugs. © 2006 Wiley Periodicals, Inc. Med Res Rev, 26, No. 4, 483,530, 2006 [source] Changes in central steroid receptor expression, steroid synthesis, and dopaminergic activity related to the reproductive cycle of the ring doveMICROSCOPY RESEARCH AND TECHNIQUE, Issue 1 2001Robert W. Lea This review examines possible neural mechanisms involved in the expression of parental behavior in the ring dove, Streptopelia risoria. This avian species has proved an excellent animal model for studies concerning endocrine-behavior interactions for many years. Studies were performed to localize the expression of central androgen and progesterone receptor in both sexes. Expression of androgen receptor (androgen receptor immunoreactivity, AR-ir) was widespread but increased, similarly in both sexes, with increasing day-length. Progesterone receptor-immunoreactivity (PR-ir) was more localized in several discrete areas of the hypothalamus. Similarly, no sex differences were observed in PR-ir, and expression increased in birds maintained on long days. AR-ir demonstrated dramatic changes over the breeding cycle, being greatest in courting birds and almost undetectable in parenting birds of both sexes brooding their young. PR-ir showed a differential expression over the breeding cycle relative to its hypothalamic localization. PR-ir decreased in the tuberal hypothalamic area in brooding birds of both sexes; whereas in the preoptic area, PR-ir was maintained. Significant increases in dopaminergic activity during the parenting phase of the breeding cycle occurred in specific neural regions including the PVM and DMA. Studies demonstrated the ability of the diencephalon of both sexes of the ring dove brain to synthesize progesterone, with indications that in the male brooding dove, synthesis is increased. Finally, a model is presented that proposes a mechanism whereby these central systems may interact to result in the expression of full parental behavior in both sexes of the ring dove. Microsc. Res. Tech. 55:12,26, 2001. © 2001 Wiley-Liss, Inc. [source] Stage-dependent and alternative splicing of sGnRH messengers in rainbow trout testis during spermatogenesisMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2001Svetlana Uzbekova Abstract The gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in the control of the reproductive cycle. However, the presence of GnRH and its receptors in various tissues, including ovary and testis, suggests a role as autocrine/paracrine factor. In the present study, we report the expression of the sGnRH-1 and sGnRH-2 genes encoding salmon GnRH in rainbow trout testis throughout testicular development and spermatogenesis. We demonstrate that both sGnRH mRNA are expressed prior of sexual differentiation. In adult, northern blot analysis indicates that sGnRH-2 transcripts are expressed in the testis at higher levels than sGnRH-1 messengers. Moreover, we observed that the expression of sGnRH-2, and not sGnRH-1, messengers was stage-dependent. sGnRH-2 mRNA expression decreases at the onset and progressively rebounds at the end of spermatogenesis. In addition, we demonstrate that a complex stage-dependent and differential splicing of the sGnRH-2 messengers occurs throughout spermatogenesis. We isolated five transcripts corresponding to sGnRH-2 messengers. Two of them may encode a novel and shortened GnRH-associated peptide containing 18 residues instead of 46. Our data provide new insight in the putative role of GnRH and GAP peptides as autocrine/paracrine factors of spermatogenesis. Mol. Reprod. Dev. 59:1,10, 2001. © 2001 Wiley-Liss, Inc. [source] Zoospore-specific antigen as a useful marker for molecular analysis of net formation in Hydrodictyon reticulatum (Chlorococcales, Chlorophyceae)PHYCOLOGICAL RESEARCH, Issue 3 2000Kyoko Hatano SUMMARY In the green alga Hydrodictyon reticulatum zoospores are arranged in a regular fashion to form an intricate hexagonal network during the asexual reproductive cycle. A monoclonal antibody which was raised against a homogenate of zoospores recognized a single poly-peptide in zoospores with a molecular mass of 31 kDa. The antigenic polypeptide, which was designated Amy1, was localized within the cytoplasm of zoospores. The accumulation of Amy1 occurred concomitantly with the transition from multinuclear vegetative cells to mononuclear zoospores, and the degradation of Amy1 occurred concomitantly with the further development of zoospores. Amy1 was constantly expressed during the period of mononuclear zoospores. Thus, we conclude that Amy1 is a zoospore-specific polypeptide. Using the anti-Amy1 monoclonal antibody, we could easily distinguish between mononuclear zoospores and multinuclear vegetative net-cells. This provides an important tool for analysing the molecular mechanisms involved in the hexagonal net formation by zoospores. [source] Limited application of homozygous genotypes in apple breedingPLANT BREEDING, Issue 4 2005L. Vanwynsberghe Abstract Apple is a temperate fruit species with several breeding disadvantages such as the highly heterozygous nature of the genome and a long reproductive cycle. It is expected that homozygous apple genotypes can increase breeding efficiency, but inbreeding is prevented by the gametophytic self-incompatibility mechanism. In this paper, the production and characterization of homozygous genotypes, generated from anther culture in Malus × domestica cv. ,Braeburn', is described as well as their potential for use in breeding programmes. After determination of large scale anther culture efficiency, anther culture-derived genotypes were simple sequence repeat (SSR)-fingerprinted to determine their homozygous nature and confirm their androgenic origin. Their value for breeding was estimated based on growth and fertility measurements. The use of homozygous androgenic genotypes from ,Braeburn' in apple breeding programmes is currently not a realistic approach, partly because of the low efficiency of anther culture, but mainly because of the reduced vigour and severe sterility of the androgenic genotypes produced. [source] Welfare Index and Reproductive Performance in the SowREPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2006C Munsterhjelm Contents To study the relationship between on-farm welfare and reproductive performance in the sow, the TGI 35L Animal Needs Index was modified for use in Finnish pig production. The modified index had a maximal total score of 100. It was comprised of six categories: ,locomotion' (maximal score 21 for dry sows and 11 for lactating sows), ,social interaction' (12/8), ,floor quality' (16/9), ,stable climate' (16/21), ,feeding' (16/23) and ,health and stockmanship' (19/29). Index scorings were performed separately in farrowing, breeding and gestation units on 28 representative Finnish sow farms. One-year production parameters were collected. Multiple linear regression was used for statistical analysis. Total ANI-points varied between 36.5,68.0 for lactating and 39.5,86.0 for dry sows. Litter size increased with increasing scores for ,feeding' in the dry sow unit. Controlling for breed, high scores for ,health and stockmanship' and ,floor quality' shortened the reproductive cycle, probably because of good leg health. The number of weaned piglets per sow per year (PSY) increased with increasing scores for dry sow ,health and stockmanship', ,floor quality' and an interaction of ,feeding' in the farrowing and mating units. PSY increased with decreasing scores for farrowing pen ,climate'. High-quality floors and stockmanship appear to correlate positively with reproductive performance in the sow. Effects of a welfare-promoting feeding strategy on reproduction are contradictory. [source] Morphological and Morphometric Changes of Pituitary Lactotrophs of Viscacha (Lagostomus maximus maximus) in Relation to Reproductive Cycle, Age, and SexTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2010Verónica Filippa Abstract Lactotrophs in pituitary pars distalis (PD) of viscacha were studied by immunohistochemistry and morphometric analysis in the following groups: 1) adult males throughout the reproductive cycle (reproductive, gonadal regression, and recovery periods), 2) melatonin-treated adults, 3) castrated adults, 4) prepubertal, 5) non-pregnant females, and 6) pregnant females (early, mid, and late pregnancy). Immunopositive percentage area (%IA), cell percentage in PD (% PDC), number of cells per reference area (no.cell/RA), major cellular and nuclear diameters were analyzed. Lactotrophs were mainly localized in the ventro,medial region and the caudal extreme of PD. In the male viscachas, they were isolated in small and big groups, close to blood vessels and near follicles. These cells were pleomorphic and with a heterogeneous cytoplasmic immunolabeling pattern. In the adult males of the gonadal regression period the morphometric parameters were the lowest. Most parameters of lactotrophs in the prepubertal were significantly lower than in the adult males in the reproductive period. In the melatonin-treated animals and in castrated animals there was a decrease in %IA, %PDC, and no.cell/RA. In the females, the morphometric parameters increased at the end of pregnancy. Non-pregnant females exhibited a higher immunopositive area and number, but a smaller size of cells than males. Our results showed that in the adult male viscacha, lactotrophs vary seasonally, probably due to the photoperiod effect through melatonin. Besides the changes observed after castration, in prepubertal animals, in adults of different sex, and during pregnancy suggest that the gonadal steroid hormones might modify the lactotrophs activity. Anat Rec, 293:150,161, 2010. © 2010 Wiley-Liss, Inc. [source] Claudin-5 is Restricted to the Tight Junction Region of Uterine Epithelial Cells in the Uterus of Pregnant/Gravid Squamate ReptilesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 5 2008Joanna M. Biazik Abstract Claudin-5, a tight junctional protein associated with ion and size selectivity, has been found in the uterus of skinks. This study has generated critical information about the molecular assembly of the tight junction at various stages of the reproductive cycle in the skink uterus. Recent studies looking at tight junctional proteins found occludin expression in the tight junction region of uterine epithelial cells in the skink uterus; however, occludin did not disclose any further information about the ions and size of ions permeating across the paracellular pathway. A ,22-kDa claudin-5 band was detected in the uterus of the skinks present in this study and immunohistochemistry revealed that claudin-5 redistributes to the tight junction region of the lateral plasma membrane of uterine epithelial cells in late stage pregnancy/gravidity. This finding indicates that the tight junction becomes more assembled to precisely regulate ion and solute permeation in late stage pregnancy/gravidity. Claudin-5 with its functional role as a molecular sieve due to the formation of ion and size selective pores suggests that permeation of ions smaller than 0.8 kDa are restricted when claudin-5 is redistributed to the tight junction region of the later plasma membrane. This report is the first description of the molecular mechanisms that may be involved in regulating nutrient provision in the reptilian uterus. Anat Rec, 291:547,556, 2008. © 2008 Wiley-Liss, Inc. [source] Ultrastructural aspects of the follicular cells of the pars tuberalis in bats related to the seasonal cycleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003Giacomo Azzali Abstract The topography and structure of the follicular cells and the follicular cavity of the hypophyseal pars tuberalis (PT) were studied in adult hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) of both sexes, during the annual seasonal cycle and the reproductive cycle. The follicular cells were found to be organized around a central cavity. They showed a polyhedral shape and apical microvilli protruding into central cavities. During hibernation, the follicular cells showed active cytoplasmic organelles, clusters of glycogen particles, and lipid droplets. In the supranuclear cytoplasm, 9+2 type cilia, some dense bodies, microvesicular vacuoles, and thin actin-like filaments (rather scarce during autumn) were detected. The contents of the follicular cavity showed well-defined ultrastructural seasonal characteristics, with a colloid-like aspect during awakening and a strongly granular aspect during autumn oestrus and mating. Positive staining for PAS and paraldehyde fuchsin, and a marked reaction to lectins PHA-L4, MAM, and RCA 60 suggested the presence of sialo-glycoproteins in the follicular cavities. Both follicular and endocrine PT-specific cells appeared to mark the boundary of follicular cavities. This finding suggests that the follicular cavity contents are comprised of both types of cells, rather than by cell fragmentation or degeneration products. Anat Rec Part A 273A:763,771, 2003. © 2003 Wiley-Liss, Inc. [source] Sexual behavior in female western lowland gorillas (Gorilla gorilla gorilla): evidence for sexual competitionAMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2009Tara S. Stoinski Abstract Previous research in gorillas suggests that females engage in post-conception mating as a form of sexual competition designed to improve their own reproductive success. This study focused on sexual behaviors in a newly formed group of western lowland gorillas (Gorilla gorilla gorilla) housed at Zoo Atlanta. All females engaged in mating outside their conceptive periods, although there was individual variation in the frequency of the behavior. An analysis of the presence/absence of sexual behavior found females, regardless of reproductive condition, were more likely to engage in sexual behavior on days when other females were sexually active. On these "co-occurrence" days, females were significantly more likely to solicit the silverback, but copulations did not differ from expectation. The results find further evidence for sexual competition among female gorillas and suggest that this may occur throughout their reproductive cycle rather than only during pregnancy. Am. J. Primatol. 71:587,593, 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||