Body fat, energy balance and estradiol levels: a study based on hormonal profiles from complete menstrual cycles

BACKGROUND: Female fecundity is regulated by nutritional status. Although widely cited, this hypothesis is not strongly supported by empirical data from non-obese, healthy women of reproductive age. METHODS: Healthy, reproductive aged women (n = 141) from Southern Poland collected daily morning saliva samples for one complete menstrual cycle. Levels of 17-b-estradiol were analyzed by radioimmunoassay. Anthropometric measurements, including body fat percentage, were taken randomly with respect to phase of the menstrual cycle. Energy balance was specified based on changes in body fat percentage from the beginning to the end of the observation period. RESULTS: Women with very low and high body fat had significantly lower levels of E2 compared with women with low and average body fat. In women of very low to average body fat, a 10% increase in body fat was associated with a 5 – 7 pmol/l increase in estradiol levels. The association between fat percentage and E2 was even stronger in women with positive energy balance, who also showed significant differences between body fat groups in estradiol profiles across whole the menstrual cycle. No such relationship was found in women with negative energy balance. CONCLUSIONS: In healthy women, we found a non-linear association between body fat and estradiol levels. Both very low and high body fat was associated with decreased estradiol levels. The relationship between estradiol and body fat was strongly influenced by women’s energy balance.AnthropologyHuman Evolutionary Biolog

Weight change and ovarian steroid profiles in young women

Objective: To investigate possible short-term effects of voluntary weight loss on ovarian steroid profiles in young women, in light of better established long-term effects in older women. Design: We tested for an association of voluntary weight change over the course of a menstrual cycle with salivary E2 and P profiles in the same menstrual cycle. Setting: Students were recruited in a college residence hall, and they provided daily saliva samples to a researcher living nearby. Patient(s): The 65 women who participated were all college students and ranged in age between 18 and 23 years. Intervention(s): None. Main Outcome Measure(s): Weight was assessed in the first week of the menstrual cycle and first week of the following menstrual cycle. Estradiol and P were measured by radioimmunoassay in daily saliva samples. Result(s): We did not detect a suppressive effect of weight loss on the overall level of either hormone. However, we did find evidence for more distinct follicular and luteal E2 peaks in women who gained weight. Peak luteal P also arrived about 2 days earlier in women who gained weight. Conclusion(s): This finding adds to evidence that short-term response of ovarian function to weight loss in young women is less pronounced than long-term response in older women.AnthropologyHuman Evolutionary Biolog

Low estradiol levels in women of reproductive age having low sleep variation

Higher exposure to light at night per se and through decrease in sleep duration and night shift work may suppress serum melatonin levels, which in turn may increase the reproductive hormone levels. High levels of steroid hormones, especially estrogens, may be associated with an increase of the breast cancer risk. This study investigated whether variation in the sleep duration during one entire menstrual cycle corresponds to variation in estradiol levels in healthy, urban women of reproductive age. Ninthy five regularly menstruating women ages 24-36 collected daily saliva samples for one entire menstrual cycle and recorded the number of hours of sleep per night (sleep duration). Saliva samples were analyzed for concentration of 17-ß estradiol (E2). We documented, after adjustments for sleep duration, a positive relationship between the sleep variation (coefficient of variation in sleep duration - sleep CV) and estradiol levels in women of reproductive age. Mean levels of E2 differed significantly in women from the lowest sleep CV quartile in comparison to other quartiles (p<0.001). The low sleep variation group, that is the women who sleep regularly, had mean E2 levels 60% lower than other groups. These results suggest that sleep variation significantly correlates with E2 levels, while sleep duration does not show a statistically significant relationship. According to the breast cancer development hypothesis, increasing the lifetime exposure to endogenous estrogens could result in higher risk of breast cancer.AnthropologyHuman Evolutionary Biolog

Pooled Energy Budget and Human Life History

Human life history contains a series of paradoxes not easily explained by classical life history theory. While overall reproductive output is higher than in related primates, juvenile growth is slower and age-specific reproductive rates decline faster with age. A simple energetic model would predict that growth and reproductive rates should be positively correlated and that reproductive effort should not decelerate with age. The pattern of negative correlations in humans suggests the presence of trade-offs among peak reproductive rate, childhood growth, and reproductive rate at older ages. To address this puzzle, we propose a synthesis of reproductive ecology and behavioral ecology focused on intra- and inter-somatic energy transfers. This integration includes three concepts: the mother as final common pathway through which energy must pass to result in offspring; a distinction between direct and indirect reproductive effort, proposing the latter as a novel net energy allocation category relative to growth and direct reproductive effort; and a pooled energy budget representing the energetic contributions and withdrawals of all members of a breeding community. Individuals at all reproductive life stages are considered in light of their contributions to the pooled energy budget. This is a preprint of an article accepted for publication in The American Journal of Human Biology © 2009 Peter T. EllisonAnthropologyHuman Evolutionary Biolog

Population variation in ovarian function

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30638/1/0000280.pd

Protective Unfolded Protein Response in Human Pancreatic Beta Cells Transplanted into Mice

Background: There is great interest about the possible contribution of ER stress to the apoptosis of pancreatic beta cells in the diabetic state and with islet transplantation. Methods and Findings: Expression of genes involved in ER stress were examined in beta cell enriched tissue obtained with laser capture microdissection (LCM) from frozen sections of pancreases obtained from non-diabetic subjects at surgery and from human islets transplanted into ICR-SCID mice for 4 wk. Because mice have higher glucose levels than humans, the transplanted beta cells were exposed to mild hyperglycemia and the abnormal environment of the transplant site. RNA was extracted from the LCM specimens, amplified and then subjected to microarray analysis. The transplanted beta cells showed an unfolded protein response (UPR). There was activation of many genes of the IRE-1 pathway that provide protection against the deleterious effects of ER stress, increased expression of ER chaperones and ERAD (ER-associated protein degradation) proteins. The other two arms of ER stress, PERK and ATF-6, had many down regulated genes. Downregulation of EIF2A could protect by inhibiting protein synthesis. Two genes known to contribute to apoptosis, CHOP and JNK, were downregulated. Conclusions: Human beta cells in a transplant site had UPR changes in gene expression that protect against the proapoptotic effects of unfolded proteins

Gene Expression Profiles of Beta-Cell Enriched Tissue Obtained by Laser Capture Microdissection from Subjects with Type 2 Diabetes

Background: Changes in gene expression in pancreatic beta-cells from type 2 diabetes (T2D) should provide insights into their abnormal insulin secretion and turnover. Methodology/Principal Findings: Frozen sections were obtained from cadaver pancreases of 10 control and 10 T2D human subjects. Beta-cell enriched samples were obtained by laser capture microdissection (LCM). RNA was extracted, amplified and subjected to microarray analysis. Further analysis was performed with DNA-Chip Analyzer (dChip) and Gene Set Enrichment Analysis (GSEA) software. There were changes in expression of genes linked to glucotoxicity. Evidence of oxidative stress was provided by upregulation of several metallothionein genes. There were few changes in the major genes associated with cell cycle, apoptosis or endoplasmic reticulum stress. There was differential expression of genes associated with pancreatic regeneration, most notably upregulation of members of the regenerating islet gene (REG) family and metalloproteinase 7 (MMP7). Some of the genes found in GWAS studies to be related to T2D were also found to be differentially expressed. IGF2BP2, TSPAN8, and HNF1B (TCF2) were upregulated while JAZF1 and SLC30A8 were downregulated. Conclusions/Significance: This study made possible by LCM has identified many novel changes in gene expression tha

COSORE: A community database for continuous soil respiration and other soil‐atmosphere greenhouse gas flux data

Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil‐to‐atmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS), is one of the largest carbon fluxes in the Earth system. An increasing number of high‐frequency RS measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open‐source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long‐term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured RS, the database design accommodates other soil‐atmosphere measurements (e.g. ecosystem respiration, chamber‐measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package

A communal catalogue reveals Earth's multiscale microbial diversity

Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe