Central Versus Peripheral Cardiovascular Risk in Metabolic Syndrome

Individuals with metabolic syndrome (MetS; i.e., three of five of the following risk factors (RFs): elevated blood pressure, waist circumference, triglycerides, blood glucose, or reduced HDL) are thought to be prone to serious cardiovascular disease and there is debate as to whether the disease begins in the peripheral vasculature or centrally. This study investigates hemodynamics, cardiac function/morphology, and mechanical properties of the central (heart, carotid artery) or peripheral [total peripheral resistance (TPR), forearm vascular bed] vasculature in individuals without (1–2 RFs: n = 28), or with (≥3 RFs: n = 46) MetS. After adjustments for statin and blood pressure medication use, those with MetS had lower mitral valve E/A ratios (<3 RFs: 1.24 ± 0.07; ≥3 RFs: 1.01 ± 0.04; P = 0.025), and higher TPR index (<3 RFs: 48 ± 2 mmHg/L/min/m2; ≥3 RFs: 53 ± 2 mmHg/L/min/m2; P = 0.04). There were no differences in heart size, carotid artery measurements, cardiovagal baroreflex, pulse-wave velocity, stroke volume index, or cardiac output index due to MetS after adjustments for statin and blood pressure medication use. The use of statins was associated with increased inertia in the brachial vascular bed, increased HbA1c and decreased LDL cholesterol. The independent use of anti-hypertensive medication was associated with decreased predicted VO2max, triglycerides, diastolic blood pressure, interventricular septum thickness, calculated left ventricle mass, left ventricle posterior wall thickness, and left ventricle pre-ejection period, but increased carotid stiffness, HDL cholesterol, and heart rate. These data imply that both a central cardiac effect and a peripheral effect of vascular resistance are expressed in MetS. These data also indicate that variance in between-group responses due to pharmacological treatments are important factors to consider in studying cardiovascular changes in these individuals

Genetic variation and structure in native populations of the fire ant Solenopsis invicta: evolutionary and demographic implications

We studied population genetic variation and structure in the fire ant Solenopsis invicta using nuclear genotypic and mitochondrial DNA (mtDNA) sequence data obtained from samples collected throughout its native range. Geographic populations are strongly differentiated at both genomes, with such structure more pronounced in Brazil than in Argentina. Higher-level regional structure is evident from the occurrence of isolation-by-distance patterns among populations, the recognition of clusters of genetically similar, geographically adjacent populations by ordination analysis, and the detection of an mtDNA discontinuity between Argentina and Brazil coinciding with a previously identified landform of biogeographical relevance. Multiple lines of evidence from both genomes suggest that the ancestors of the ants we studied resembled extant northern Argentine S. invicta, and that existing Brazilian populations were established more recently by serial long-distance colonizations and/or range expansions. The most compelling evidence for this is the corresponding increase in F-K (a measure of divergence from a hypothetical ancestor) and decrease in genetic diversity with distance from the Corrientes population in northern Argentina. Relatively deep sequence divergence among several mtDNA clades, coupled with geographical partitioning of many of them, suggests prolonged occupation of South America by S. invicta in more-or-less isolated regional populations. Such populations appear, in some cases, to have come into secondary contact without regaining the capacity to freely interbreed. We conclude that nominal S. invicta in its native range comprises multiple entities that are sufficiently genetically isolated and diverged to have embarked on independent evolutionary paths

Assessing genetic structure with multiple classes of molecular markers: a case study involving the introduced fire ant Solenopsis invicta

We used 30 genetic markers of 6 different classes to describe hierarchical genetic structure in introduced populations of the fire ant Solenopsis invicta. These included four classes of presumably neutral nuclear loci (allozymes, codominant random amplified polymorphic DNAs (RAPDs), microsatellites, and dominant RAPDs), a class comprising two linked protein-coding nuclear loci under selection, and a marker of the mitochondrial DNA (mtDNA). Patterns of structure revealed by F statistics and exact tests of differentiation were highly concordant among the four classes of neutral nuclear markers, although the microsatellites were the most effective markers for detecting structure. The results from the mtDNA complemented those from the neutral nuclear markers by revealing that strong limitations to female-mediated gene flow were the cause of the local structure registered by the nuclear markers. The pattern of structure inferred from the selected nuclear loci was markedly different from the patterns derived from the other sets of markers but was predictable on the basis of the presumed mode of selection acting on these loci. In general, the results for all six classes of markers can be explained by known features of the social and reproductive biology of fire ants. Thus, the results from these diverse sets of markers, combined with detailed natural history data, provide an unusually complete picture of how the fundamental evolutionary forces of gene flow, drift, and selection govern the distribution of genetic variation within and between fire ant populations

Distribution and prevalence of Wolbachia infections in native populations of the fire ant Solenopsis invicta (Hymenoptera : Formicidae)

Wolbachia are endosymbiotic bacteria that commonly infect arthropods. These bacteria induce a number of phenotypes in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization, and male killing. We surveyed native South American populations of the fire ant Solenopsis invicta Buren for Wolbachia infections by using a diagnostic polymerase chain reaction assay. In addition, we determined the fidelity of vertical transmission of the bacteria from mother to offspring in this species by assaying daughters in 24 simple-family (monogyne) colonies. Infections were common in many parts of the extensive native range of S. invicta. However, the proportion of individuals infected varied greatly among samples, ranging from zero in several populations from the northerly parts of the range to &gt;90% in more southerly populations. Possible explanations for this variation in the prevalence of Wolbachia infections are discussed. A survey of the two social forms of S. invicta from four geographic areas showed that the prevalence of Wolbachia infections consistently was higher in the monogyne form (single queen per colony) than the sympatric polygyne form (multiple queens per colony). One likely explanation for this trend is that the selective regimes acting on Wolbachia in the two forms differ because of the dissimilar reproductive strategies used by each form. Finally, overall transmission efficiency was found to be very high (&gt;99%), making it unlikely that imperfect transmission prevents the spread of the microbe to near fixation in native populations

Wolbachia infections in native and introduced populations of fire ants (Solenopsis spp.)

Wolbachia are cytoplasmically inherited bacteria that induce a variety of effects with fitness consequences on host arthropods, including cytoplasmic incompatibility, parthenogenesis, male-killing and feminization. We report here the presence of Wolbachia in native South American populations of the fire ant Solenopsis invicta, but the apparent absence of the bacteria in introduced populations of this pest species in the USA. The Wolbachia strains in native S. invicta are of two divergent types (A and B), and the frequency of infection varies dramatically between geographical regions and social forms of this host. Survey data reveal that Wolbachia also are found in other native fire ant species within the Solenopsis saevissima species complex from South America, including S. richteri. This latter species also has been introduced in the USA, where it lacks Wolbachia. Sequence data reveal complete phylogenetic concordance between mtDNA haplotype in S. invicta and Wolbachia infection type (A or B). In addition, the mtDNA and associated group A Wolbachia strain in S. invicta are more closely related to the mtDNA and Wolbachia strain found in S. richteri than they are to the mtDNA and associated group B Wolbachia in S. invicta. These data are consistent with historical introgression of S. richteri cytoplasmic elements into S. invicta populations, resulting in enhanced infection and mtDNA polymorphisms in S. invicta. Wolbachia may have significant fitness effects on these hosts (either directly or by cytoplasmic incompatibility) and therefore these microbes potentially could be used in biological control programmes to suppress introduced fire ant populations

Distribution of the two social forms of the fire ant Solenopsis invicta (Hymenoptera : Formicidae) in the native South American range

Polygyne (multiple queen) colony social organization in the fire ant Solenopsis invicta Buren is always associated with the presence of a particular class of alleles at the gene Gp-9. We used diagnostic polymerase chain reaction assays capable of distinguishing these alleles to determine the location of polygyne populations in the native South American range of this species. We found that polygyny occurs in a mosaic pattern with respect to the more common monogyne (single queen) social form, a pattern superficially similar to that seen in the introduced range in the United States. However, polygyny appears to be relatively restricted in its geographical prevalence in the native range compared with the introduced range. This difference may stem from higher dispersal rates in the introduced range, which are associated with greater opportunities for human-mediated transport of mated queens or colony fragments. On the basis of our distributional data and results from other studies, the southern part of the native range of S. invicta, particularly northeastern Argentina, is emerging as the most likely geographic source of the founders of the U.S. population

Amino acid transport in schistosomes: Characterization of the permeaseheavy chain SPRM1hc

Schistosomes are human parasitic flatworms that constitute an important public health problem globally. Adult parasites live in the bloodstream where they import nutrients such as amino acids across their body surface (the tegument). One amino acid transporter, Schistosome Permease 1 light chain, SPRM1lc, a member of the glycoprotein-associated family of transporters (gpaAT), has been characterized in schistosomes. Only a single member of the SLC3 family of glycoproteins that associate with gpaATs is found following extensive searching of the genomes of Schistosoma mansoni and S. japonicum. In this report, we characterize this schistosome permease heavy chain (SPRM1hc) gene and protein. The 72-kDa gene product is predicted to possess a single transmembrane domain, a (betaalpha)(8) (TIM barrel) conformation and a catalytic triad. Xenopus oocytes functionally expressing SPRM1hc with SPRM1lc import phenylalanine, arginine, lysine, alanine, glutamine, histidine, tryptophan, and leucine. Biochemical characterization demonstrates that in Xenopus extracts and in schistosome extracts SPRM1hc is associated into a high molecular weight complex with SPRM1lc that is disrupted by reducing agents. Quantitative real-time PCR and Western analysis demonstrate that SPRM1hc is expressed in each schistosome life stage examined (eggs, cercariae, schistosomula, adult males and females). SPRM1hc is widely distributed throughout adult male and female worms as determined by immunolocalization. Consistent with the hypothesis that SPRM1hc functions to facilitate nutrient uptake from host blood, immunogold electron microscopy confirms that the protein is distributed on the host-interactive tegumental membranes. We propose that surface-exposed, host-interactive, nutrient-transporting proteins like the SPRM1 heterodimer are promising vaccine candidates

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in the special issue for the conference proceedings of GWDAW13; corrected some typos, addressed some minor reviewer comments one section restructured and references updated and correcte

The Role of Oxygen in Stimulating Methane Production in Wetlands

Methane (CH4), a potent greenhouse gas, is the second most important greenhouse gas contributor to climate change after carbon dioxide (CO2). The biological emissions of CH4 from wetlands are a major uncertainty in CH4 budgets. Microbial methanogenesis by Archaea is an anaerobic process accounting for most biological CH4 production in nature, yet recent observations indicate that large emissions can originate from oxygenated or frequently oxygenated wetland soil layers. To determine how oxygen (O2) can stimulate CH4 emissions, we used incubations of Sphagnum peat to demonstrate that the temporary exposure of peat to O2 can increase CH4 yields up to 2000-fold during subsequent anoxic conditions relative to peat without O2 exposure. Geochemical (including ion cyclotron resonance mass spectrometry, X-ray absorbance spectroscopy) and microbiome (16S rDNA amplicons, metagenomics) analyses of peat showed that higher CH4 yields of redox-oscillated peat were due to functional shifts in the peat microbiome arising during redox oscillation that enhanced peat carbon (C) degradation. Novosphingobium species with O2-dependent aromatic oxygenase genes increased greatly in relative abundance during the oxygenation period in redox-oscillated peat compared to anoxic controls. Acidobacteria species were particularly important for anaerobic processing of peat C, including in the production of methanogenic substrates H2 and CO2. Higher CO2 production during the anoxic phase of redox-oscillated peat stimulated hydrogenotrophic CH4 production by Methanobacterium species. The persistence of reduced iron (Fe(II)) during prolonged oxygenation in redox-oscillated peat may further enhance C degradation through abiotic mechanisms (e.g., Fenton reactions). The results indicate that specific functional shifts in the peat microbiome underlie O2 enhancement of CH4 production in acidic, Sphagnum-rich wetland soils. They also imply that understanding microbial dynamics spanning temporal and spatial redox transitions in peatlands is critical for constraining CH4 budgets; predicting feedbacks between climate change, hydrologic variability, and wetland CH4 emissions; and guiding wetland C management strategies