Variants in the Adiponectin Gene and Serum Adiponectin: The Coronary Artery Development in Young Adults (CARDIA) Study

Circulating adiponectin is involved in the atherosclerotic process and has been associated with cardiovascular disease as well as obesity, insulin resistance, metabolic syndrome, and type 2 diabetes. The adiponectin gene (ADIPOQ) encodes the circulating protein adiponectin and affects its expression. Only a small proportion of all known ADIPOQ polymorphisms have been investigated in relation to circulating adiponectin concentrations. Using data from 3,355 African‐American and white men and women aged 33–45 at the year 15 examination from the Coronary Artery Development in Young Adults (CARDIA) Study the association between 10 single‐nucleotide polymorphisms (SNPs) within ADIPOQ and serum adiponectin was examined using linear regression. SNPs were chosen based on a tagSNP approach. Models were stratified by self‐reported race to control for population stratification, and Bonferroni corrected for multiple comparisons. ADIPOQ SNPs rs17300539 (P < 0.0001), rs182052 (P = 0.0013), rs822393 (P = 0.0005), rs9882205 (P = 0.0001), and rs3774261 (P = 0.0001) were strongly associated with serum adiponectin concentrations in whites. In general, there was a dose‐response relationship of adjusted mean adiponectin concentrations across genotypes. Only one SNP, rs17300539 was marginally associated with serum adiponectin concentrations (P = 0.0087) in African Americans. Significant interactions were found between waist and rs182052 (P = 0.0029) and between rs9882505 and smoking (P = 0.001) in whites. Many ADIPOQ SNPs have not yet been examined, and additional studies are needed to determine whether these may be functional variants.     

Genetic variants in <Emphasis Type="Italic">TLR2</Emphasis> and <Emphasis Type="Italic">TLR4</Emphasis> are associated with markers of monocyte activation: the Atherosclerosis Risk in Communities MRI Study

Markers of monocyte activation play a critical role in atherosclerosis, but little is known about the genetic influences on cellular levels. Therefore, we investigated the influence of genetic variants in monocyte differentiation antigen (CD14), toll-like receptor-4 (TLR4), toll-like receptor-2 (TLR2), and myeloperoxidase (MPO) on monocyte surface receptor levels. The study sample consisted of 1,817 members of a biracial cohort of adults from the Atherosclerosis Risk in Communities Carotid MRI Study. Monocyte receptors were measured using flow cytometry on fasting whole blood samples. TLR2 rs1816702 genotype was significantly associated with CD14+/TLR2+ percent of positive cells (%) and median fluorescence intensity (MFI) in whites but not in blacks (p < 0.001). Specifically, the presence of the minor T-allele was associated with increased receptor levels. In blacks, TLR4 rs5030719 was significantly associated with CD14+/TLR4+ monocytes (MFI) with mean ± SE intensities of 16.7 ± 0.05 and 16.0 ± 0.14 for GG and GT/TT genotypes, respectively (p < 0.001). Variants in TLR2 and TLR4 were associated with monocyte receptor levels of TLR2 and TLR4, respectively, in a biracial cohort of adults. To our knowledge, this is the first study to look at associations between variants in the toll-like receptor family and toll-like receptor levels on monocytes.     

Imputation of missing covariate values in epigenome-wide analysis of DNA methylation data

DNA methylation is a widely studied epigenetic mechanism and alterations in methylation patterns may be involved in the development of common diseases. Unlike inherited changes in genetic sequence, variation in site-specific methylation varies by tissue, developmental stage, and disease status, and may be impacted by aging and exposure to environmental factors, such as diet or smoking. These non-genetic factors are typically included in epigenome-wide association studies (EWAS) because they may be confounding factors to the association between methylation and disease. However, missing values in these variables can lead to reduced sample size and decrease the statistical power of EWAS. We propose a site selection and multiple imputation (MI) method to impute missing covariate values and to perform association tests in EWAS. Then, we compare this method to an alternative projection-based method. Through simulations, we show that the MI-based method is slightly conservative, but provides consistent estimates for effect size. We also illustrate these methods with data from the Atherosclerosis Risk in Communities (ARIC) study to carry out an EWAS between methylation levels and smoking status, in which missing cell type compositions and white blood cell counts are imputed.     

Blood group antigen loci demonstrate multivariate genetic associations with circulating cellular adhesion protein levels in the Multi-Ethnic Study of Atherosclerosis

The cellular adhesion pathway is critical in the pathophysiology of atherosclerosis, and genetic factors contributing to regulation of circulating levels of related proteins may be relevant to risk prediction of cardiovascular disease. In contrast to conducting separate genome-wide protein quantitative trait loci (pQTL) mapping analyses of each individual protein, joint genetic association analyses of multiple quantitative traits can leverage cross-trait co-variation and identify simultaneous regulatory effects on protein levels across the pathway. We conducted a multi-pQTL (mpQTL) analysis of 15 proteins related to cellular adhesion assayed on 2313 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). We applied the MQFAM multivariate association analysis method in PLINK on normalized protein level residuals derived from univariate linear regression, adjusting for age, sex, and principal components of ancestry. Race/ethnicity-stratified analyses identified nine genome-wide significant (P < 5e?08) loci associated with co-variation of protein levels. Although the majority of these SNPs were in proximity to structural genes of the assayed proteins, we discovered multiple loci demonstrating co-association with the circulation of at least two proteins. Of these, two significant loci specific to non-Hispanic white participants, rs17074898 at ALOX5AP (P = 1.78E?08) and rs7521237 at KIAA1614 (P = 2.2E?08), would not have met statistical significance using univariate analyses. Moreover, common patterns of multi-protein associations were discovered at the ABO locus across race/ethnicity. These results indicate the biological relevance of blood group antigens on regulation of circulating cellular adhesion pathway proteins while also demonstrating race/ethnicity-specific co-regulatory effects.     

Heterogeneous binding of high mobility group chromosomal proteins to nuclei

A dramatic difference is observed in the intracellular distribution of the high mobility group (HMG) proteins when chicken embryo fibroblasts are fractionated into nucleus and cytoplasm by either mass enucleation of cytochalasin-B-treated cells or by differential centrifugation of mechanically disrupted cells. Nuclei (karyoplasts) obtained by cytochalasin B treatment of cells contain more than 90 percent of the HMG 1, while enucleated cytoplasts contain the remainder. A similar distribution between karyoplasts and cytoplasts is observed for the H1 histones and the nucleosomal core histones as anticipated. The presence of these proteins, in low amounts, in the cytoplast preparation can be accounted for by the small percentage of unenucleated cells present. In contrast, the nuclei isolated from mechanically disrupted cells contain only 30-40 percent of the total HMGs 1 and 2, the remainder being recovered in the cytosol fraction. No histone is observed in the cytosol fraction. Unike the higher molecular weight HMGs, most of the HMGs 14 and 17 sediment with the nuclei after cell lysis by mechanical disruption. The distribution of HMGs is unaffected by incubating cells with cytochalasin B and mechanically fractionating rather than enucleating them. Therefore, the dramatic difference in HMG 1 distribution observed using the two fractionation techniques cannot be explained by a cytochalasin-B-induced redistribution. On reextraction and sedimentation of isolated nuclei obtained by mechanical cell disruption, only 8 percent of the HMG 1 is released to the supernate. Thus, the majority of the HMG 1 originally isolated with these nuclei, representing 35 percent of the total HMG 1, is stably bound, as is all the HMGs 14 and 17. The remaining 65 percent of the HMGs 1 and 2 is unstably bound and leaks to the cytosol fraction under the conditions of mechanical disruption. It is suggested that the unstably bound HMGs form a protein pool capable of equilibrating between cytoplasm and stably bound HMGs.     

Daten zur Schlafdauer in der Herde Asiatischer Elefanten (Elephas maximus) im Zoologischen Garten Berlin

Due to the night observations during the gravidity of the Asian Elephant “Pang Pha” in 2005 it was possible to receive data on the sleeping behavior of 1.3 Asian elephants (Elephas maximus) at Berlin Zoological Garden. These elephants were the breeding bull “Victor” (born 22.10.1993 at Zoological Center Ramat Gan), “Pang Pha” (born 1987 in Thailand), “Drumbo” (born 1970) and “Iyoti” (born 1974 in India). Elephant “Pang Pha” slept only one and a half hour, whereas the two older cows lay nearly four hours. The bull lay longest.