Retracted: Experimental evidence that maternal corticosterone controls adaptive offspring sex ratios

1. Sex allocation theory has received considerable attention, yet the mechanism(s) by which mothers skew offspring sex ratios remain unknown. In birds, females are the heterogametic sex, which potentially gives them control of whether gametes will be male or female. How females might control the sex of the gamete is unclear, but one possibility is that variation in steroid hormones may mediate this process. 2. We experimentally altered circulating levels of corticosterone in female Gouldian finches (Erythrura gouldiae), a species that demonstrates both extreme stress responses and extreme offspring sex ratio biases when breeding with a low-quality (genetically incompatible) partner. 3. During egg production, individual females received both corticosterone and metyrapone (a corticosterone-synthesis inhibitor) implants, in random order, to induce both high and low levels of circulating stress hormones (within physiological limits). 4. We found that females with elevated corticosterone levels produced male-biased sex ratios, but when the same females were treated with metyrapone they produced female-biased offspring sex ratios. 5. These stress responses are adaptive because females constrained to breeding with low-quality males can substantially increase their fitness by overproducing sons. Changes in maternal corticosterone levels during stressful situations, such as the quality of a breeding partner, may provide an endocrine mechanism that can be exploited for strategic sex allocation.

Female body condition affects foetal growth in a capital breeding mysticete

1.Sex allocation theory has received considerable attention, yet the mechanism(s) by which mothers skew offspring sex ratios remain unknown. In birds, females are the heterogametic sex, which potentially gives them control of whether gametes will be male or female. How females might control the sex of the gamete is unclear, but one possibility is that variation in steroid hormones may mediate this process. 2.We experimentally altered circulating levels of corticosterone in female Gouldian finches (Erythrura gouldiae), a species that demonstrates both extreme stress responses and extreme offspring sex ratio biases when breeding with a low-quality (genetically incompatible) partner. 3.During egg production, individual females received both corticosterone and metyrapone (a corticosterone-synthesis inhibitor) implants, in random order, to induce both high and low levels of circulating stress hormones (within physiological limits). 4.We found that females with elevated corticosterone levels produced male-biased sex ratios, but when the same females were treated with metyrapone they produced female-biased offspring sex ratios. 5.These stress responses are adaptive because females constrained to breeding with low-quality males can substantially increase their fitness by overproducing sons. Changes in maternal corticosterone levels during stressful situations, such as the quality of a breeding partner, may provide an endocrine mechanism that can be exploited for strategic sex allocation.

Climate change, multiple paternity and offspring survival in lizards

Recent work suggests that rising spring temperatures over recent decades have eliminated many lizard populations, and threaten many more worldwide. However, because ambient temperatures constrain activity times in ectotherms, warming conditions (as expected under global climate change scenarios) can increase the duration of seasonal opportunities for courtship and mating. Thus, in species where polyandry results in enhanced offspring viability, a warming climate may not necessarily impair long-term survival. Our nine-year study of a sand lizard (Lacerta agilis) population near the northern range limit in Sweden revealed consistently higher incidence of multiple paternity of clutches in warmer years, and higher viability of offspring from multiply-sired clutches (presumably reflecting the advantages of more intense sperm competition). Any trend to warmer spring temperatures likely will benefit offspring viability in this system, by increasing a female's opportunities to mate with additional males.

Maternal dietary supplementation with saturated, but not monounsaturated or polyunsaturated fatty acids, leads to tissue-specific inhibition of offspring Na+,K+-ATPase

In rats, a maternal diet rich in lard is associated with reduced Na+,K+-ATPase activity in adult offspring kidney. We have addressed the role of different fatty acids by evaluating Na+,K+-ATPase activity in offspring of dams fed diets rich in saturated (SFA), monounsaturated (MUFA) or polyunsaturated (PUFA) fatty acids. Female Sprague–Dawley rats were fed, during pregnancy and suckling, a control diet (4% w/w corn oil) or a fatty acid supplemented diet (24% w/w). Offspring were reared on chow (4% PUFA) and studied at 6 months. mRNA expression (real-time PCR) of Na+,K+-ATPase α subunit and protein expression of Na+,K+-ATPase subunits (Western blot) were assessed in kidney and brain. Na+,K+-ATPase activity was reduced in kidney (P < 0.05 versus all groups) and brain (P < 0.05 versus control and MUFA offspring) of the SFA group. Neither Na+,K+-ATPase α1 subunit mRNA expression, nor protein expression of total α, α1, α2, α3 or β1 subunits were significantly altered in kidney in any dietary group. In brains of SFA offspring α1 mRNA expression (P < 0.05) was reduced compared with MUFA and PUFA offspring, but not controls. Also in brain, SFA offspring demonstrated reduced (P < 0.05) α1 subunit protein and increased phosphorylation (P < 0.05) of the Na+,K+-ATPase modulating protein phospholemman at serine residue 63 (S63 PLM). Na+,K+-ATPase activity was similar to controls in heart and liver. In utero and neonatal exposure to a maternal diet rich in saturated fatty acids is associated with altered activity and expression of Na+,K+-ATPase in adulthood, but mechanisms appear tissue specific.

IUGR in the absence of postnatal 'catch-up' growth leads to improved whole body insulin sensitivity in rat offspring

A suboptimal in utero environment leads to fetal adaptations to ensure short-term survival but in the long-term may lead to disease when the postnatal growth does not reflect that in utero. This study examined the effect of IUGR on whole body insulin sensitivity and metabolic activity in adult rats. Female Wistar-Kyoto rats were fed either a normal protein diet (NPD 20% casein) or a low protein diet (LPD; 8.7% casein) during pregnancy and 2 wk of lactation. In offspring at 32 wk of age, indirect calorimetry and dual energy x-ray absorptiometry (DEXA) were performed to assess metabolic activity and body composition. Insulin sensitivity was assessed using a euglycemic-hyperinsulinemic clamp. At 3 d of age, male and female LPD offspring were 23 and 27% smaller than controls, respectively. They remained significantly smaller throughout the experimental period (~10% smaller at 32 wk). Importantly, there was increased insulin sensitivity in LPD offspring (47% increase in males and 38% increase in females); pancreatic insulin content was normal. Body composition, O2 consumption, respiratory exchange ratio (RER), and locomotor activity were not different to controls. These findings suggest that in the absence of “catch-up” growth IUGR programs for improved insulin sensitivity.

Maternal overnutrition programs changes in the expression of skeletal muscle genes that are associated with insulin resistance and defects of oxidative phosphorylation in adult male rat offspring.

Children of obese mothers have increased risk of metabolic syndrome as adults. Here we report the effects of a high-fat diet in the absence of maternal obesity at conception on skeletal muscle metabolic and transcriptional profiles of adult male offspring. Female Sprague Dawley rats were fed a diet rich in saturated fat and sucrose [high-fat diet (HFD): 23.5% total fat, 9.83% saturated fat, 20% sucrose wt:wt] or a normal control diet [(CD) 7% total fat, 0.5% saturated fat, 10% sucrose wt:wt] for the 3 wk prior to mating and throughout pregnancy and lactation. Maternal weights were not different at conception; however, HFD-fed dams were 22% heavier than controls during pregnancy. On a normal diet, the male offspring of HFD-fed dams were not heavier than controls but demonstrated features of insulin resistance, including elevated plasma insulin concentration [40.1 ± 2.5 (CD) vs 56.2 ± 6.1 (HFD) mU/L; P = 0.023]. Next-generation mRNA sequencing was used to identify differentially expressed genes in the offspring soleus muscle, and gene set enrichment analysis (GSEA) was used to detect coordinated changes that are characteristic of a biological function. GSEA identified 15 upregulated pathways, including cytokine signaling (P < 0.005), starch and sucrose metabolism (P < 0.017), inflammatory response (P < 0.024), and cytokine-cytokine receptor interaction (P < 0.037). A further 8 pathways were downregulated, including oxidative phosphorylation (P < 0.004), mitochondrial matrix (P < 0.006), and electron transport/uncoupling (P < 0.022). Phosphorylation of the insulin signaling protein kinase B was reduced [2.86 ± 0.63 (CD) vs 1.02 ± 0.27 (HFD); P = 0.027] and mitochondrial complexes I, II, and V protein were downregulated by 50-68% (P < 0.005). On a normal diet, the male offspring of HFD-fed dams did not become obese adults but developed insulin resistance, with transcriptional evidence of muscle cytokine activation, inflammation, and mitochondrial dysfunction. These data indicate that maternal overnutrition, even in the absence of prepregnancy obesity, can promote metabolic dysregulation and predispose offspring to type 2 diabetes.

Fathers with highly demanding partners and offspring in a semidesert environment: energetic aspects of the breeding system of Monteiro's Hornbills (Tockus monteiri) in Namibia

Molting females of Monteiro's Hornbills (Tockus monteiri) seal themselves in nest cavities to breed until chicks are about half grown. To gain insight into the chronology of energy requirements of the Monteiro's Hornbill family unit in relation to this peculiar breeding strategy, we measured a number of ecological, physiological, and environmental variables during the Monteiro's Hornbill's breeding season. Those measurements included rates of energy expenditure of female Monteiro's Hornbills while in the nest cavity, characterizing their thermal environment, timing of egg laying, molt, hatching and fledging of chicks, as well as measuring clutch size and chick growth. Temperatures within the nest box varied between 12 and 39°C and did not affect the female energy expenditure. Female body mass and energy expenditure averaged 319 g and 5 W, respectively, at the start of concealment and decreased by on average 1.1 g day -1 and 0.05 W day -1 during at least the first 30 days of the 52-58 day concealment period. Clutch size varied between 1 and 8 and averaged 4.1 eggs, with eggs averaging only 66% of the mass predicted for a bird of this size. Over the range of chick ages at which the female might leave the nest, the predicted energy requirements for maintenance and tissue growth for a Monteiro's Hornbill chick increase sharply from 1.2 W at age 8 to 3.0 W at age 25. Reduction of the female energy requirement with time, the relatively low growth rate and therewith low energy requirements of Monteiro's Hornbill chicks, and an appropriate timing of the female's exodus from the nest cavity all aid in containing peak energy demands to levels that are sustainable for the food provisioning male.

Sequential polyandry through divorce and re-pairing in a cooperatively breeding bird reduces helper-offspring relatedness

Polyandry is an important component of both sexual selection and kin structuring within cooperatively breeding species. A female may have multiple partners within a single reproductive attempt (simultaneous polyandry) or across multiple broods within and/or across years (sequential polyandry). Both types of polyandry confer a range of costs and benefits to individuals and alter the genetic structure of social groups over time. To date, many molecular studies of cooperative breeders have examined the evolution of cooperative breeding in relation to simultaneous polyandry. However, cooperatively breeding vertebrates are iteroparous, and thus sequential polyandry is also likely, but more rarely considered in this context. We examined sequential polyandry in a cooperatively breeding bird that has a low level of within-brood polyandry. Over a 5-year period (2006–2010), we monitored individual mating relationships using molecular markers in a population of individually marked apostlebirds (Struthidea cinerea). Divorce occurred between reproductive seasons in 17 % (8/48) of pairs and appeared to be female-driven. The level of sequential polyandry was also driven by the disappearance of males after breeding, and over 90 % of females, for whom we had suitable data, bred with multiple males over the period of study. This sequential polyandry significantly altered the relatedness of group members to the offspring in the nest. However, in about half of the cases, the second male was related (first- or second-order relative) to the first male of a sequentially polyandrous female and this alleviated the reduction in relatedness caused by polyandry. Our findings suggest that even in species with high within-brood parentage certainty, helper-offspring relatedness values can quickly erode through sequential polyandry.

Association of birth weight and current body size to blood pressure in female twins

It has been proposed that low birth weight is associated with high levels of blood pressure in later life. The aim of this study was to assess the relationship of blood pressure to birth weight and current body size during growth and adulthood. A total of 711 female multiple births, with one group of 244 in their growth phase mean age 12.0 (2.3)(SD) years and the other of 467 adults (mean age 35.2 (12.6) years), had height, weight and both systolic (SBP) and diastolic (DBP) blood pressures measured, and self-reported their birth weight. Regression analyses were performed to assess the cross-sectional and within-pair associations of blood pressure to birth weight, with and without adjustments for current body size. Within-pair analysis was based on 296 twin pairs. Cross-sectionally, a reduction in birth weight of 1 kg was associated with 2 to 3 mm Hg higher age-adjusted SBP, which was of marginal significance and explained about 2% of the population variance. Adjustment for body mass index did not significantly change this association. Within-pair analyses found no association between birth weight and SBP or DBP,even after adjusting for current body size. After age, current body size was the strongest predictor of systolic BP. The weak association of blood pressure to birth weight cross-sectionally is of interest, but any within-pair effect of birth weight on blood pressure must be minimal compared with the effect of current body size.

Menstrual dysfunction and bone health in female athletes

Female athletes are generally considered to be at Iow risk of osteoporosis because of the skeletal loading associated with sports participation. Sites that are exposed to long-term high-impact loading are consistently reported to be higher than the same sites in their sedentary peers. However, weight-bearing exercise does not always ensure that athletes will have high bone-mineral density, as the hormonal environment, dietary factors, and loading history all influence bone-mineral density, In particular, menstrual dysfunction, which can occur with intense training or disordered eating, is a significant risk factor for Iow bone-mineral density. Exercise history before menstrual dysfunction is likely to offer some protection for Iow bone-mineral density, particularly at the hip, Resumption of menses is unlikely to restore bone-mineral density to levels reported in eumenorrheic athletes or even sedentary peers, Athletes at risk of amenorrhea should be identified and their training loads and energy intakes monitored to ensure normal menstrual function, Athletes who remain amenorrheic should be counseled about the possible negative effects of amenorrhea and monitored for bone loss. Early intervention is recommended for amenorrheic athletes with Iow bone-mineral density.

Do we need a new classification system for female sexual dysfunction? A comment on the 1999 consensus classification system.

This Article does not have an abstract.

A chance to bloom: female migration and salvationists in Australia and Canada, 1890s to 1939

Migration is usually analysed as a function of state policy of sending and receiving countries in the context of global movements of people. Thus, despite their sponsorship and support of thousands of migrants, independent, voluntary, religious and ethnic organisations have often been marginalised in international migration studies. This article arises from a broader investigation into the role of such organisations in the peopling of Australia and Canada from the 1890s to 1939: their visions, relationships with governments, significance and legacies. The aim is to bring a new perspective to comparative migration and population research and to assess how far such organisations paralleled, or stepped outside of, the racialised, gendered and class structures of ofŽficial immigration policies and  practices of the time. Here the focus is particularly on the place of women and girls in the migration schemes of some of the organisations operating in both Australia and Canada. The use of case studies such as the British Women’s Emigration Association, the Salvation Army and Dr Barnardo’s Homes provides an opportunity to examine the sexual distinctions implicit in these schemes and the direction of both women and men into what were seen at the time as gender-appropriate societal roles and occupations.

Self-reported work and family stress of female primary teachers

Stress arising in the domain of work and family can have a cumulative effect, and can spill over across the domains. The work-family interface has  received little attention in teacher stress research, therefore the present study aimed to investigate work and family stress among teachers. Self-report questionnaires were distributed to 102 female, primary teachers from government schools in the Geelong area. Responses were used to: (a) identify the major work and family stressors; (b) identify the contributions of perceived work and family stress to perceived global stress; and (c) explore the impact that work and family stress have on each other. Overall the teachers reported moderate levels of global, work and family stress. Time and workload pressure was the major work stressor, and responsibility for child rearing the major family stressor. Work stress and home stress both impacted on each other. The implications of the findings were discussed.