BackgroundObesity and phenotypic traits associated with this condition exhibit significant heritability in natural populations of most organisms. While a number of genes and genetic pathways have been implicated to play a role in obesity associated traits, the genetic architecture that underlies the natural variation in these traits is largely unknown. Here, we used 40 wild-derived inbred lines of Drosophila melanogaster to quantify genetic variation in body weight, the content of three major metabolites (glycogen, triacylglycerol, and glycerol) associated with obesity, and metabolic rate in young flies. We chose these lines because they were previously screened for variation in whole-genome transcript abundance and in several adult life-history traits, including longevity, resistance to starvation stress, chill-coma recovery, mating behavior, and competitive fitness. This enabled us not only to identify candidate genes and transcriptional networks that might explain variation for energy metabolism traits, but also to investigate the genetic interrelationships among energy metabolism, behavioral, and life-history traits that have evolved in natural populations.ResultsWe found significant genetically based variation in all traits. Using a genome-wide association screen for single feature polymorphisms and quantitative trait transcripts, we identified 337, 211, 237, 553, and 152 novel candidate genes associated with body weight, glycogen content, triacylglycerol storage, glycerol levels, and metabolic rate, respectively. Weighted gene co-expression analyses grouped transcripts associated with each trait in significant modules of co-expressed genes and we interpreted these modules in terms of their gene enrichment based on Gene Ontology analysis. Comparison of gene co-expression modules for traits in this study with previously determined modules for life-history traits identified significant modular pleiotropy between glycogen content, body weight, competitive fitness, and starvation resistance.ConclusionsCombining a large phenotypic dataset with information on variation in genome wide transcriptional profiles has provided insight into the complex genetic architecture underlying natural variation in traits that have been associated with obesity. Our findings suggest that understanding the maintenance of genetic variation in metabolic traits in natural populations may require that we understand more fully the degree to which these traits are genetically correlated with other traits, especially those directly affecting fitness.

Syndecans are a family of type-I transmembrane proteins that are involved in cell-matrix adhesion, migration, neuronal development, and inflammation. Previous quantitative genetic studies pinpointed Drosophila Syndecan (dSdc) as a positional candidate gene affecting variation in fat storage between two Drosophila melanogaster strains. Here, we first used quantitative complementation tests with dSdc mutants to confirm that natural variation in this gene affects variability in Drosophila fat storage. Next, we examined the effects of a viable dSdc mutant on Drosophila whole-body energy metabolism and associated traits. We observed that young flies homozygous for the dSdc mutation had reduced fat storage and slept longer than homozygous wild-type flies. They also displayed significantly reduced metabolic rate, lower expression of spargel (the Drosophila homologue of PGC-1), and reduced mitochondrial respiration. Compared to control flies, dSdc mutants had lower expression of brain insulin-like peptides, were less fecund, more sensitive to starvation, and had reduced life span. Finally, we tested for association between single nucleotide polymorphisms (SNPs) in the human SDC4 gene and variation in body composition, metabolism, glucose homeostasis, and sleep traits in a cohort of healthy early pubertal children. We found that SNP rs4599 was significantly associated with resting energy expenditure (P = 0.001 after Bonferroni correction) and nominally associated with fasting glucose levels (P = 0.01) and sleep duration (P = 0.044). On average, children homozygous for the minor allele had lower levels of glucose, higher resting energy expenditure, and slept shorter than children homozygous for the common allele. We also observed that SNP rs1981429 was nominally associated with lean tissue mass (P = 0.035) and intra-abdominal fat (P = 0.049), and SNP rs2267871 with insulin sensitivity (P = 0.037). Collectively, our results in Drosophila and humans argue that syndecan family members play a key role in the regulation of body metabolism.

We previously reported that a higher degree of methylation of CpG sites in the promoter (positions 31, 37, 43, 52 and 58) and enhancer site 7862 of HPV 16 was associated with a lower likelihood of being diagnosed with HPV 16-associated CIN 2+. The purpose of the current study was to replicate our previous findings and in addition to evaluate the influence of plasma concentrations of folate and vitamin B12 on the degree of HPV 16 methylation (HPV 16m). The study included 315 HPV 16 positive women diagnosed with either CIN 2+ or ≤ CIN 1. Pyrosequencing technology was used to quantify the degree of HPV 16m. We reproduced the previously reported inverse association between HPV 16m and risk of being diagnosed with CIN 2+. In addition, we observed that women with higher plasma folate and higher HPV 16m or those with higher plasma vitamin B12 and higher HPV 16m were 75% (P<0.01) and 60% (P=0.02) less likely to be diagnosed with CIN 2+, respectively. With a tertile increase in the plasma folate or vitamin B12, there was a 50% (P=0.03) and 40% (P=0.07) increase in the odds of having a higher degree of HPV 16m, respectively. The present study provides initial evidence that methyl donor micronutrients, folate and vitamin B12, may play an important role in maintaining a desirably high degree of methylation at specific CpG sites in the HPV E6 promoter and enhancer that are associated with the likelihood of being diagnosed with CIN 2+.

Background: The objective of the present study was to map candidate loci influencing naturally occurring variation in triacylglycerol (TAG) storage using quantitative complementation procedures in Drosophila melanogaster. Based on our results from Drosophila, we performed a human population-based association study to investigate the effect of natural variation in LAMA5 gene on body composition in humans.

Background While urine based testing for human papillomavirus (HPV) is being explored as a practical approach for cervical cancer screening, whether the results differ by age, race and indicators of excess body weight or in populations exposed to HPV vaccines have not been documented by previous studies. The purpose of the study was to determine the accuracy of urinary HPV testing for presence of cervical HPVs and high grade cervical intraepithelial lesions (CIN 2 and 3) by the above stated population characteristics. Methods Study population consisted of 502 women diagnosed with different grades of CIN. HPV testing was performed with paired urine and cervical cell DNA using Roche Diagnostics Linear Array. Agreement coefficient 1 (AC1) and probabilities were calculated to determine the accuracy of urinary HPV testing for the presence of cervical HPVs and CIN lesions. Results We observed a substantial to almost perfect agreement (0.66–0.83) in the detection of any HPV genotype in urine compared to cervical specimens irrespective of population characteristics. Although the PPV for detection of CIN lesions was relatively low, the NPV for CIN 3 was high (≥ 90%) among women positive for any of the urinary or cervical HR-HPV genotypes or HPV genotypes not included in currently available HPV vaccines. Conclusions Our results demonstrated that urine HPV testing provides highly satisfactory results for excluding the possibility of having any cervical HPV infections, including HPV types not included in vaccines and CIN lesions associated with any HR-HPV regardless of woman’s age, race and excess body weight.