Intrapopulation foraging niche variation between phenotypes and genotypes of Spirit bear populations

Foraging niche variation within a species can contribute to the maintenance of phenotypic diversity. The multiniche model posits that phenotypes occupying different niches can contribute to the maintenance of balanced polymorphisms. Using coastal populations of black bears (Ursus americanus kermodei) from British Columbia, Canada, we examined potential foraging niche divergence between phenotypes (black and white “Spirit” coat color) and between genotypes (black‐coated homozygote and heterozygous). We applied the Bayesian multivariate models, with biotracers of diet (δ¹³C and δ¹⁵N) together comprising the response variable, to draw inference about foraging niche variation. Variance–covariance matrices from multivariate linear mixed‐effect models were visualized as the Bayesian standard ellipses in δ¹³C and δ¹⁵N isotopic space to assess potential seasonal and annual niche variation between phenotypes and genotypes. We did not detect a difference in annual isotopic foraging niche area in comparisons between genotypes or phenotypes. Consistent with previous field experimental and isotopic analyses, however, we found that white phenotype Spirit bears were modestly more enriched in δ¹⁵N during the fall foraging season, though with our modest sample sizes these results were not significant. Although also not statistically significant, variation in isotopic niches between genotypes revealed that heterozygotes were moderately more enriched in δ¹³C along hair segments grown during fall foraging compared with black‐coated homozygotes. To the extent to which the pattern of elevated δ¹⁵N and δ¹³C may signal the consumption of salmon (Oncorhynchus spp.), as well as the influence of salmon consumption on reproductive fitness, these results suggest that black‐coated heterozygotes could have a minor selective advantage in the fall compared with black‐coated homozygotes. More broadly, our multivariate approach, coupled with knowledge of genetic variation underlying a polymorphic trait, provides new insight into the potential role of a multiniche mechanism in maintaining this rare morph of conservation priority in Canada''s Great Bear Rainforest and could offer new understanding into polymorphisms in other systems.     

A splice variant of the Drosophila vesicular monoamine transporter contains a conserved trafficking domain and functions in the storage of dopamine, serotonin, and octopamine

Vesicular monoamine transporters (VMATs) mediate the transport of dopamine (DA), serotonin (5HT), and other monoamines into secretory vesicles. The regulation of mammalian VMAT and the related vesicular acetylcholine transporter (VAChT) has been proposed to involve membrane trafficking, but the mechanisms remain unclear. To facilitate a genetic analysis of vesicular transporter function and regulation, we have cloned the Drosophila homolog of the vesicular monoamine transporter (dVMAT). We identify two mRNA splice variants (DVMAT-A and B) that differ at their C-terminus, the domain responsible for endocytosis of mammalian VMAT and VAChT. DVMAT-A contains trafficking motifs conserved in mammals but not C. elegans, and internalization assays indicate that the DVMAT-A C-terminus is involved in endocytosis. DVMAT-B contains a divergent C-terminal domain and is less efficiently internalized from the cell surface. Using in vitro transport assays, we show that DVMAT-A recognizes DA, 5HT, octopamine, tyramine, and histamine as substrates, and similar to mammalian VMAT homologs, is inhibited by the drug reserpine and the environmental toxins 2,2,4,5,6-pentachlorobiphenyl and heptachlor. We have developed a specific antiserum to DVMAT-A, and find that it localizes to dopaminergic and serotonergic neurons as well as octopaminergic, type II terminals at the neuromuscular junction. Surprisingly, DVMAT-A is co-expressed at type II terminals with the Drosophila vesicular glutamate transporter. Our data suggest that DVMAT-A functions as a vesicular transporter for DA, 5HT, and octopamine in vivo, and will provide a powerful invertebrate model for the study of transporter trafficking and regulation.     

The Effects of Silicone Fluid Additives and Silicone Elastomer Matrices on Barnacle Adhesion Strength

Barnacle adhesion strength was used to screen seventy-seven polydimethylsiloxane elastomeric coatings for fouling-release properties. The test coatings were designed to investigate the effect on barnacle adhesion strength of silicone fluid additive type, additive location, additive molecular weight, additive loading level, mixtures of additives, coating matrix type and coating fillers. The type of silicone fluid additive was the primary controlling factor in barnacle fouling-release. The type of silicone matrix in which the fluid resided was found to alter the effect on fouling-release. Two PDMS fluids, DMSC15 and DBE224, significantly reduced the adhesion strength of barnacles compared to unmodified elastomers. Optimum fouling-release performance was dependent on the interaction of fluid type and elastomeric matrix.     

K2P18.1 translates T cell receptor signals into thymic regulatory T cell development

It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv...     

Use of gas chromatography-mass spectrometry/solid phase microextraction for the identification of MVOCs from moldy building materials

Gas chromatography-mass spectrometry/solid phase microextraction (GC-MS/SPME) was applied to identify microbial volatile organic compounds (MVOCs) in water-damaged, mold-infested building materials (gypsum board papers (n=2), mineral wool, and masonite) and in cultivated molds (Aspergillus penicillioides, Stachybotrys chartarum, and Chaetomium globosum). Three SPME fibers (65-microm PDMS-DVB, 75-microm Carboxen-PDMS, and 70-microm Carbowax-stableflex) designed for automated injection were used of which the latter showed best performance. A number of previously reported MVOCs were detected both in the building materials and the cultivated molds. In addition, methyl benzoate was identified both in the S. chartarum and A. penicillioides cultures and in the building materials. SPME combined with GC-MS may be a useful method for the determination of MVOCs emitted from mold-infested building materials.     

CaGE: cardiac gene expression knowledgebase

CaGE is a Cardiac Gene Expression knowledgebase we have developed to facilitate the analysis of genes important to human cardiac function. CaGE integrates the functionality of the LocusLink database with data from several human cardiac expression libraries, phenotypic data from OMIM and data from large-scale microarray gene expression studies to create a knowledgebase of gene expression in human cardiac tissue. The knowledgebase is fully searchable via the web using several intuitive query interfaces. Results can be displayed in several concise easy to navigate formats. AVAILABILITY: CaGE is located at http://www.cage.wbmei.jhu.edu     

Platform Engineering of Corynebacterium glutamicum with Reduced Pyruvate Dehydrogenase Complex Activity for Improved Production of l-Lysine,l-Valine,and 2-Ketoisovalerate

Exchange of the native Corynebacterium glutamicum promoter of the aceE gene, encoding the E1p subunit of the pyruvate dehydrogenase complex (PDHC), with mutated dapA promoter variants led to a series of C. glutamicum strains with gradually reduced growth rates and PDHC activities. Upon overexpression of the l-valine biosynthetic genes ilvBNCE, all strains produced l-valine. Among these strains, C. glutamicum aceE A16 (pJC4 ilvBNCE) showed the highest biomass and product yields, and thus it was further improved by additional deletion of the pqo and ppc genes, encoding pyruvate:quinone oxidoreductase and phosphoenolpyruvate carboxylase, respectively. In fed-batch fermentations at high cell densities, C. glutamicum aceE A16 Δpqo Δppc (pJC4 ilvBNCE) produced up to 738 mM (i.e., 86.5 g/liter) l-valine with an overall yield (Y_P/S) of 0.36 mol per mol of glucose and a volumetric productivity (Q_P) of 13.6 mM per h [1.6 g/(liter × h)]. Additional inactivation of the transaminase B gene (ilvE) and overexpression of ilvBNCD instead of ilvBNCE transformed the l-valine-producing strain into a 2-ketoisovalerate producer, excreting up to 303 mM (35 g/liter) 2-ketoisovalerate with a Y_P/S of 0.24 mol per mol of glucose and a Q_P of 6.9 mM per h [0.8 g/(liter × h)]. The replacement of the aceE promoter by the dapA-A16 promoter in the two C. glutamicum l-lysine producers DM1800 and DM1933 improved the production by 100% and 44%, respectively. These results demonstrate that C. glutamicum strains with reduced PDHC activity are an excellent platform for the production of pyruvate-derived products.     

Hemopoietic cell expression of the chemokine decoy receptor D6 is dynamic and regulated by GATA1

D6 scavenges inflammatory chemokines and is essential for the regulation of inflammatory and immune responses. Mechanisms explaining the cellular basis for D6 function have been based on D6 expression by lymphatic endothelial cells. In this study, we demonstrate that functional D6 is also expressed by murine and human hemopoietic cells and that this expression can be regulated by pro- and anti-inflammatory agents. D6 expression was highest in B cells and dendritic cells (DCs). In myeloid cells, LPS down-regulated expression, while TGF-beta up-regulated expression. Activation of T cells with anti-CD3 and soluble CD28 up-regulated mRNA expression 20-fold, while maturation of human macrophage and megakaryocyte precursors also up-regulated D6 expression. Competition assays demonstrated that chemokine uptake was D6 dependent in human leukocytes, whereas mouse D6-null cells failed to uptake and clear inflammatory chemokines. Furthermore, we present evidence indicating that D6 expression is GATA1 dependent, thus explaining D6 expression in myeloid progenitor cells, mast cells, megakaryocytes, and DCs. We propose a model for D6 function in which leukocytes, within inflamed sites, activate D6 expression and thus trigger resolution of inflammatory responses. Our data on D6 expression by circulating DCs and B cells also suggest alternative roles for D6, perhaps in the coordination of innate and adaptive immune responses. These data therefore alter our models of in vivo D6 function and suggest possible discrete, and novel, roles for D6 on lymphatic endothelial cells and leukocytes.