Sexual differences of the effects of prenatal stress on the expression of extracellular signal-regulated kinaseas in the hippocampus of offspring rats

BACKGROUND： Prenatal stress has been shown to inhibit cell proliferation in the dentate gyrus and hippocampus, reduce hippocampal volume, and cause neuronal loss and oxidative damage in the hippocampus of offspring rats, but the sexual difference of the effects on offsprings is seldom referred to. OBJECTIVE： To observe the effect of prenatal stress to adult pregnant rats on expression of extracellular signal-regulated kinases （ERK） in hippocampus of the offspring rats of different genders. DESIGN ： A randomized and control animal experiment.SETTING： Department of Physiology and Pathophysiology, School of Medicine, Xi＇an Jiaotong University. MATERIALS ： The experiments were carried out in the Key Laboratory of Environment and Gene Related Diseases （Xi＇an Jiaotong University）, Ministry of Education between October 2005 and March 2006. Fifteen female and five male adult Sprague-Dawley rats were adopted. Female rats weighing 230-250 g and male rats weighing 280-350 g were used. METHODS： The virgin female rats were placed overnight with adult male rats （3：1） for mating. A total of twelve pregnant rats were randomly assigned to prenatal stress group （PNS group, n=6） and control group （n=6）. The pregnant rats of the PNS group were exposed to restraint stress on days 14-20 of pregnancy three times a day, 45 minutes for each time . The restraint device was a transparent plastic tube （6.8 cm in diameter） with air holes for breathing and closed end. The length could be adjusted to accommodate the size of the animals. To prevent habituation of animals to the daily procedure, restraint periods were randomly shifted within certain time periods （8：00-11：00, 11：00-14：00, and 16：00-19：00）. After birth, offsprings of all groups were culled to 8-10 litters in each group and housed in the same animal room, and kept together with their biologic mothers. The pregnant rats of the control group were left undisturbed. On day 21, after all the offspring were weaned, male and female pups were separated and housed four in each cage respectively until test at 30 days of age. At the end of postnatal day 30, one male and female offspring rats from the same dam were selected with a random choice and a total of 24 animals from 12 different dams were used. The experimental rats were sacrificed by decapitation under anesthesia. Bilateral hippocampal tissues were isolated and homogenized in cold condition. Alkaline carbonate buffer （BCA） method was used to detect the concentration of extracellular signal-regulated kinases （ERK）, then mixed with loading buffer, the constant voltage was 100 V. Finally, BCIP/NBT staining and electrDphoresis were performed, the absorbance （A） value for the bands was detected with the Bandscan analytical software, and the expression of ERK in hippocampus of offspring rats of different genders in each group was quantitatively analyzed. MAIN OUTCOME MEASURES： The level of ERK expression in hippocampus of offspring rats of different genders in each group was observed.RESULTS： All the 24 offspring rats were involved in the analysis of results. ① The staining results of ERP activity in the extract of brain tissue detected with Western blotting technique and specific antibody analysis showed that the ERP in hippocampus of offspring rats had two subtypes of ERK-1 and ERK-2, and the latter was the main type.② Standardized by the average A value in the control group, the quantitative data of the general A value of total ERK showed that the expression of ERK-2 in hippocampus of female offspring rats was obviously higher in the PNS group than in the control group （A value： 126±6.76,100±4.89,P〈 0.01）. ③The expression of ERK-2 had no obvious difference between the female and male offspring rats in the control group.④ The expression of ERK-2 in hippocampus of male offspring rats was a little higher in the PNS group than in the control group （A value： 104±6.27,102±5.48,P 〉 0.05）. CONCLUSION ： PNS significantly affects the increase of ERK expression in hippocampus of female offspring rats, but has no obvious influence on that of male ones.

Invasion and defense of the basic social unit in a nonhuman primate society leads to sexual differences in the gut microbiome

Multilevel society is one of the most complex social systems in natural ecosystems and is a typical feature among some primates.Given the potential connection between social behavior and gut microbiome composition,the multilevel social system could affect the primate gut microbiome.Here,based on long-term observation(e.g.social unit dynamics,transfer,and behavior),we investigated this potential integrating 16S rRNA gene amplicon sequencing and behavior data in Yunnan snub-nosed monkeys(Rhinopithecus bieti),which possess a multilevel social group based on one male units(OMUs,each unit with several breeding females and their offspring)and all-male unit(AMU,several bachelor males residing together).We found that the mean unweighted Unifrac distance between adult males from different OMUs was significantly lower than that between adult females from different OMUs(paired Wilcoxon test,P=0.007).There was no significant difference in the mean unweighted Unifrac distance between females within the same OMU or between females from different OMUs.These findings indicated the potential connection between the defense and invasion of social units and the gut microbiome community in wild Yunnan snub-nosed monkeys.We speculated that the resident males of OMUs displaying a significantly higher similarity in the gut microbial community than that of adult females in separate OMUs might be associated with the sexual differences in their interactions and from previously having cohabitated together in the AMU.Therefore,this study suggested that multilevel societies might have an effect on the gut microbial community in this wild nonhuman primate species.

Philosophy, Feminist Literary Criticism and ＂The Difference＂

This paper discusses the present-day philosophical rupture away from identitarian thinking, and how the former has influenced the world of the feminist literary criticism of today. Herein, we embark on a journey from its awakenings back in the 1960s. We begin our quest with Kate Millett, we will continue our discussion with Irigaray, Cixous, or Kristeva and their analysis of the difference created by gender. And, we will reflect on the influence it has made to the American movement. We use the aforementioned as the lead towards the theory of deconstruction in authors such as Felman or Spivak, and how we reach the concept of performativity of gender in line with Butler and the queer theory.

Functional explanation of extreme hatching asynchrony: Male Manipulation Hypothesis

Hatching asynchrony in birds is considered an adaptation to facilitate brood reduction because under conditions of food scarcity, the smallest nestling usually dies soon after hatching, thereby minimizing parental effort. However, in species with extreme hatching asynchrony, the last hatchlings paradoxically experience a very low probability of survival and death can take so long that it can hardly be considered an adaptation. Here, we propose and experimentally tested a new adaptive hypothesis explaining the brood reduction paradox, namely the“Male Manipulation Hypothesis”. Our hypothesis suggests that by inducing asynchronous hatching,females increase the feeding requirements of the brood, which will induce males to increase provisioning effort. In addition, females may extend the period of male manipulation by feeding the smallest nestling just enough to sustain life. Our study showed that male common blackbirds(Turdus merula) increased their effort(i.e., number of food items per hour) in experimental asynchronous broods compared to synchronous broods, while females reduced their contribution, as predicted by the hypothesis.

Prehibernation Energy Storage in Heilongjiang Brown Frogs(Rana amurensis) from Five Populations in North China

Energy storage is an important component in the life history of species that directly inlfuences survival and reproduction. The energetic demands of amphibian reproduction can differ between the sexes, with environmental conditions, reproductive pattern or process of the species, and depending upon the timing of breeding, and the reproductive season for a species. Surprisingly, comparative studies of pre-hibernation energy storage for anuran populations from different latitudes are relatively few in Asia, especially in China. Here we investigated the patterns of pre-hibernation energy storage of Heilongjiang brown frogsRana amurensis, based on ifve populations along a ifnely latitudinal gradient in north China （40.7–43.7°N）. We found that pre-hibernation energy storage of the frogs did not show a clear latitudinal cline, but differed strongly between the sexes, with males depositing more energy reserves into the muscle and liver, whereas females accumulate more energy in the gonads. The sexual differences in energy storage may result from differential timing of energy allocation for reproduction.