Home About us Contact
|
Home About us Contact | ||
|
|
||
Female Neonates (female + neonate)
Selected AbstractsFemale-biased natal and breeding dispersal in an alpine lizard, Niveoscincus microlepidotusBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2003MATS OLSSON We measured two aspects of dispersal in the alpine Australian scincid lizard, Niveoscincus micolepidotus: (1) natal dispersal, i.e. shift in home range over the lizard's first year of life, and (2) breeding dispersal, i.e. shifts of home ranges between breeding attempts as adults. On average, displacements were surprisingly small. Female neonates dispersed about twice as far as did males in the same cohort (means of 12 m vs. 6 m). A female's natal dispersal distance was not correlated with her body size or our estimate of physiological performance (sprint speed). However, larger, faster-running male neonates dispersed further than did smaller, slower males. As was the case for neonates, adult females moved significantly further between breeding seasons than did adult males (14.2 m vs. 9.6 m). Because of a female's long gestation period (more than 1 year), two groups of females occur simultaneously in the population, non-ovulated (i.e. with yolking folicles) and pregnant females (i.e. approaching parturition). Females that were not yet ovulated showed a markedly stronger dispersal in response to high reproductive effort (i.e. clutch size in relation to body condition) than did pregnant females. In adult males, body size was negatively correlated with dispersal distance, suggesting that although males have overlapping territories, they exhibit an increasing level of site tenacity with age and/or size. Thus, selection for the relatively more pronounced site tenacity in adult males may have resulted in the more marked philopatric behaviour compared to females also as neonates. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 79, 277,283. [source] Glutamate AMPA/kainate receptors, not GABAA receptors, mediate estradiol-induced sex differences in the hypothalamusDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2007Brigitte J. Todd Abstract Sex differences in brain morphology underlie physiological and behavioral differences between males and females. During the critical perinatal period for sexual differentiation in the rat, gonadal steroids act in a regionally specific manner to alter neuronal morphology. Using Golgi-Cox impregnation, we examined several parameters of neuronal morphology in postnatal day 2 (PN2) rats. We found that in the ventromedial nucleus of the hypothalamus (VMN) and in areas just dorsal and just lateral to the VMN that there was a sex difference in total dendritic spine number (males greater) that was abolished by treating female neonates with exogenous testosterone. Dendritic branching was similarly sexually differentiated and hormonally modulated in the VMN and dorsal to the VMN. We then used spinophilin, a protein that positively correlates with the amount of dendritic spines, to investigate the mechanisms underlying these sex differences. Estradiol, which mediates most aspects of masculinization and is the aromatized product of testosterone, increased spinophilin levels in female PN2 rats to that of males. Muscimol, an agonist at GABAA receptors, did not affect spinophilin protein levels in either male or female neonates. Kainic acid, an agonist at glutamatergic AMPA/kainate receptors, mimicked the effect of estradiol in females. Antagonizing AMPA/kainate receptors with NBQX prevented the estradiol-induced increase in spinophilin in females but did not affect spinophilin level in males. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source] Difference in the sensitivity to chemical compounds between female and male neonates of Daphnia magnaENVIRONMENTAL TOXICOLOGY, Issue 5 2008Erika Ikuno Abstract Daphnia magna usually produce female offspring by parthenogenesis, and thus only female neonates are used to evaluate the environmental toxicity to chemicals. Additionally, it is known that male daphnids are induced by exposure to a juvenile hormone, methyl farnesoate, during late ovarian development. In this study, we investigated the concentration of methyl farnesoate in a 24-h exposure producing 100% males, and the difference in sensitivity to chemical compounds, potassium dichromate, pentachlorophenol, and paraquat, between females and males, referring to OECD Test Guideline 202. The results show that the minimum concentration for 100%-male induction of methyl farnesoate in adult females was 50 ,g/L. In addition, acute toxicity tests (immobility test) with the other chemicals showed that male neonates have higher tolerance to potassium dichromate and pentachlorophenol than females for at least 24 h after birth, while no sex difference was observed in the sensitivity to paraquat. The differences in the median effective concentrations in these compounds between female and male neonates suggest two different overall modes of action. Using female daphnids for environmentally toxicity testing seems reasonable, since the females are more sensitive to chemicals than males. Furthermore, the method of male induction established in this study could be used for screening of endocrine disruptors. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Cord blood thyroid-stimulating hormone and free T4 levels in Turkish neonates: Is iodine deficiency still a continuing problem?PEDIATRICS INTERNATIONAL, Issue 5 2010Fatih K Abstract Background:, The objectives of this study were to determine the cord blood thyroid-stimulating hormone (TSH) and free T4 (FT4) levels in Turkish neonates and to determine whether these variables reveal iodine deficiency. Methods:, We collected 818 cords from healthy mothers at parturition and measured levels of FT4 and TSH. We also measured cord blood FT4 and TSH levels in different stages of gestation and gender. We grouped the neonates according to cord serum TSH levels, either being less (Group A) or greater (Group B) than 10 mIU/L. Group A included 589 neonates (300 girls [51%] and 289 boys [49%]) and Group B included 229 neonates (105 girls [45%] and 124 boys [55%]). Results:, The percentage of subjects with cord blood TSH < 10 mIU/L and >10 mIU/L was 72% and 28%, respectively. Although cord TSH levels in Group B were greater than those in Group A (P < 0.001), cord blood FT4 levels in Group B were lower than those in Group A (P < 0.05). There was no difference between both sex in terms of birthweight and maternal age. TSH and FT4 levels did not vary according to neonate sex during gestation, except for from week 37 to 41. TSH levels of male neonates at the 41st week of gestation were higher than those of female neonates (P < 0.05). There were no effects of birthweight on TSH and FT4 levels if the neonate was lighter than 2500 g at birth. TSH levels of male neonates were higher than those of female neonates when their birthweights were <2500 g (P < 0.05). There was no significant difference in TSH levels according to birthweights in male neonates. Conclusion:, Our data provide the normative data for cord blood TSH and FT4 levels in Turkish neonates and show that iodine deficiency is a still a public health problem in Turkey. These measurements can be useful for detection and verification of hypothyroidism in a screening program for congenital hypothyroidism as well as evaluation of the success of the iodination program. [source] Maternal and neonatal outcomes of pregnancies complicated by asthma in an Australian populationAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 6 2009Vicki L. CLIFTON Objective:, To determine if there are sex differences in risk and incidence of stillbirth, preterm delivery and small-for-gestational age (SGA) in pregnancies complicated by maternal asthma relative to a non-asthmatic population. Study design:, Univariant and multiple regression analysis of the incidence of preterm delivery, SGA and stillbirth in singleton pregnancies complicated by asthma in Newcastle, NSW, Australia, from 1995 to 1999. Results:, Asthma complicated 12% of all singleton pregnancies. The incidence of preterm delivery was not significantly different between asthmatic (13%) and non-asthmatic (11%) pregnancies. Male fetuses (53%) were more likely to deliver preterm than female fetuses (47%) in both asthmatic and non-asthmatic populations. There were significantly more male neonates of pregnancies complicated by asthma that were SGA at term relative to those of the non-asthmatic population. There were significantly more preterm female neonates that were SGA in pregnancies complicated by asthma relative to those of the non-asthmatic population. Male fetuses were more likely to be associated with a stillbirth in pregnancies complicated by asthma than female fetuses. Conclusion:, The presence of maternal asthma during pregnancy increases the risk of stillbirth for the male fetus and is associated with changes in fetal growth, but does not increase the incidence of a preterm delivery. [source] | |||||||||||||