Linkage Analysis of Factors Underlying Insulin Resistance: Strong Heart Family Study

In previous work in non‐diabetic participants of the Strong Heart Family Study, we identified three heritable principal components of nine insulin resistance (IR) phenotypes: 1) a glucose/insulin/obesity factor, 2) a blood pressure factor, and 3) a dyslipidemia factor. To localize quantitative trait loci (QTL) potentially influencing these factors, we conducted a genome scan of factor scores in Strong Heart Family Study participants. Approximately 599 men and women, ≥18 years of age, in 32 extended families at three centers (in Arizona, Oklahoma, and North and South Dakota), were examined between 1997 and 1999. We used variance components linkage analysis to identify QTLs for the IR factors. With age, sex, and study center as covariates, we detected linkage of the glucose/insulin/obesity factor to chromosome 4 (robust logarithm of the odds (LOD) = 2.2), the dyslipidemia factor to chromosome 12 (robust LOD = 2.7), and the blood pressure factor to chromosome 1 (robust LOD = 1.6). The peak linkage signals identified for these IR factors support several positive findings from other studies and occur in regions harboring interesting candidate genes. The corroboration of existing QTLs will bring us closer to the identification of the functional genes that predispose to IR.     

A numerical taxonomic study of psychrotrophic bacteria associated with lipolytic spoilage of raw milk

Raw milk samples were stored for 1–4 d and examined for bacterial growth and lipase activity. Thirty-six samples in which an increase in the heat-stable lipase activity was observed during storage were selected for further study. From these raw milk samples 205 lipolytic psychrotrophic strains were selected using butterfat agar and subsequently characterized with 86 taxonomic tests. Complete linkage cluster analysis of the taxonomic data produced two major and six minor clusters at the 83% similarity level. Pseudomonas fluorescens and Ps. fragi accounted for 63.9 and 31.2%, respectively, of the isolates.     

Fine-Scale Habitat Selection by Breeding White-Tailed Ptarmigan in Colorado

Species distributions are influenced by climate and topography in alpine ecosystems, yet resource selection studies of alpine species are uncommon. Basic characteristics of habitats used by alpine-endemic white-tailed ptarmigan (Lagopus leucura) have been described to explain foraging behavior, morphology, and survival in many alpine regions; however, there is a lack of information about fine-scale habitat selection for nesting and brood-rearing, particularly in the southern extent of the species’ range. Few studies have tested whether nest and brood-site selection by white-tailed ptarmigan are influenced by fine-scale components such as vegetation and arthropod communities. We assessed these fine-scale habitat characteristics analyzing paired use-available resource selection for nest (n = 61) and brood (n = 54) sites. We used conditional logistic regression for data collected in 2 alpine areas along the Front Range of Colorado, USA, during 2014 and 2015. We evaluated resource selection at larger (patch) and finer (nest site) scales. Nest-site selection at the patch scale was best predicted by cover (%) of forage forbs, rock and gravel, and shrubs. Forage forb cover explained more variation in our top nest model at the patch scale when compared to models with specific vegetation species. Females placed their nests along elevational gradients but more so at lower elevations and selected for less graminoid cover at the nest-site scale. Brood habitat selection at the patch level was influenced by cover (%) of rock and gravel and proximity to shrubs (m). Analysis of a subset of our brood data (n = 34) revealed females selected brood habitat that contained high arthropod abundance (e.g., Cicadellidae) over high vegetation cover, likely as a response to meet dietary requirements of chicks. Our results demonstrate how and where white-tailed ptarmigan are currently selecting these different breeding sites in Colorado's alpine, giving us insight into consequences this alpine-endemic bird may face if their breeding habitat is altered. © 2019 The Wildlife Society.     

Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida

The discovery of six specimens of the enigmatic order Siphoniulida, including for the first time males, prompted a modern re‐analysis of current phylogenetic schemes for the class Diplopoda derived from traditional morphological and developmental characters. The data matrix was constructed and analysed using paup . The resulting phylogenetic hypotheses corroborated the longest standing, traditional classification, but also demonstrated clearly that more characters must be included to reach a better resolution. Recent alternative phylogenetic hypotheses and classifications are discussed in the light of the current analysis. The validity of a putative helminthomorph synapomorphy, the location of male gonopods on the 7th body ring, is discussed. Scanning electron microscopy corroborated morphological characters already described for the Siphoniulida: modified anterior legs, an apparently legless 3rd body ring, pyriform head, antennae with clavate setae, and absence of ozopores. The highly modified gonopods of the Siphoniulida are described for the first time; only the anterior legs of the 7th ring are modified into gonopods, the posterior legs of this ring are developed as normal walking legs. The gnathochilarium differs from the Colobognatha and consists of well‐developed stipites with palps, elongated lingual plates with palps and a narrow central sclerite, most likely the mentum. Structures on the epiproct may possibly be spinnerets. Despite the discovery of adult males, the Siphoniulida are still considered Helminthomorpha incertae sedis .     

Substrate‐driven conformational changes in ClC‐ec1 observed by fluorine NMR

The CLC ‘Cl⁻ channel'' family consists of both Cl⁻/H⁺ antiporters and Cl⁻ channels. Although CLC channels can undergo large, conformational changes involving cooperativity between the two protein subunits, it has been hypothesized that conformational changes in the antiporters may be limited to small movements localized near the Cl⁻ permeation pathway. However, to date few studies have directly addressed this issue, and therefore little is known about the molecular movements that underlie CLC-mediated antiport. The crystal structure of the Escherichia coli antiporter ClC-ec1 provides an invaluable molecular framework, but this static picture alone cannot depict the protein movements that must occur during ion transport. In this study we use fluorine nuclear magnetic resonance (NMR) to monitor substrate-induced conformational changes in ClC-ec1. Using mutational analysis, we show that substrate-dependent ¹⁹F spectral changes reflect functionally relevant protein movement occurring at the ClC-ec1 dimer interface. Our results show that conformational change in CLC antiporters is not restricted to the Cl⁻ permeation pathway and show the usefulness of ¹⁹F NMR for studying conformational changes in membrane proteins of known structure.