Scale-specific sex-biased dispersal in the Valais shrew unveiled by genetic variation on the Y chromosome, autosomes, and mitochondrial DNA.

We investigated sex specificities in the evolutionary processes shaping Y chromosome, autosomes, and mitochondrial DNA patterns of genetic structure in the Valais shrew (Sorex antinorii), a mountain dwelling species with a hierarchical distribution. Both hierarchical analyses of variance and isolation-by-distance analyses revealed patterns of population structure that were not consistent across maternal, paternal, and biparentally inherited markers. Differentiation on a Y microsatellite was lower than expected from the comparison with autosomal microsatellites and mtDNA, and it was mostly due to genetic variance among populations within valleys, whereas the opposite was observed on other markers. In addition, there was no pattern of isolation by distance for the Y, whereas there was strong isolation by distance on mtDNA and autosomes. We use a hierarchical island model of coancestry dynamics to discuss the relative roles of the microevolutionary forces that may induce such patterns. We conclude that sex-biased dispersal is the most important driver of the observed genetic structure, but with an intriguing twist: it seems that dispersal is strongly male biased at large spatial scale, whereas it is mildly biased in favor of females at local scale. These results add to recent reports of scale-specific sex-biased dispersal patterns, and emphasize the usefulness of the Y chromosome in conjunction with mtDNA and autosomes to infer sex specificities.

Genetic Association of Recovery from Eating Disorders: The Role of GABA Receptor SNPs.

Follow-up studies of eating disorders (EDs) suggest outcomes ranging from recovery to chronic illness or death, but predictors of outcome have not been consistently identified. We tested 5151 single-nucleotide polymorphisms (SNPs) in approximately 350 candidate genes for association with recovery from ED in 1878 women. Initial analyses focused on a strictly defined discovery cohort of women who were over age 25 years, carried a lifetime diagnosis of an ED, and for whom data were available regarding the presence (n=361 ongoing symptoms in the past year, ie, 'ill') or absence (n=115 no symptoms in the past year, ie, 'recovered') of ED symptoms. An intronic SNP (rs17536211) in GABRG1 showed the strongest statistical evidence of association (p=4.63 × 10(-6), false discovery rate (FDR)=0.021, odds ratio (OR)=0.46). We replicated these findings in a more liberally defined cohort of women age 25 years or younger (n=464 ill, n=107 recovered; p=0.0336, OR=0.68; combined sample p=4.57 × 10(-6), FDR=0.0049, OR=0.55). Enrichment analyses revealed that GABA (γ-aminobutyric acid) SNPs were over-represented among SNPs associated at p<0.05 in both the discovery (Z=3.64, p=0.0003) and combined cohorts (Z=2.07, p=0.0388). In follow-up phenomic association analyses with a third independent cohort (n=154 ED cases, n=677 controls), rs17536211 was associated with trait anxiety (p=0.049), suggesting a possible mechanism through which this variant may influence ED outcome. These findings could provide new insights into the development of more effective interventions for the most treatment-resistant patients.

Immunization Update, Winter 2013

Monthly newsletter for the Iowa Department of Public Health

Human epidermal Langerhans cells express the tight junction protein claudin-1 and are present in human genetic claudin-1 deficiency (NISCH syndrome).

Claudin-1 (CLDN1) is a structural tight junction (TJ) protein and is expressed in differentiating keratinocytes and Langerhans cells in the epidermis. Our objective was to identify immunoreactive CLDN1 in human epidermal Langerhans cells and to examine the pattern of epidermal Langerhans cells in genetic human CLDN1 deficiency [neonatal ichthyosis, sclerosing cholangitis (NISCH) syndrome]. Epidermal cells from healthy human skin labelled with CLDN1-specific antibodies were analysed by confocal laser immunofluorescence microscopy and flow cytometry. Skin biopsy sections of two patients with NISCH syndrome were stained with an antibody to CD1a expressed on epidermal Langerhans cells. Epidermal Langerhans cells and a subpopulation of keratinocytes from healthy skin were positive for CLDN1. The gross number and distribution of epidermal Langerhans cells of two patients with molecularly confirmed NISCH syndrome, however, was not grossly altered. Therefore, CLDN1 is unlikely to play a critical role in migration of Langerhans cells (or their precursors) to the epidermis or their positioning within the epidermis. Our findings do not exclude a role of this TJ molecule once Langerhans cells have left the epidermis for draining lymph nodes.

Elicitation of specific cytotoxic T cells by immunization with malaria soluble synthetic polypeptides.

We have studied the immunogenicity of Plasmodium falciparum circumsporozoite (CS) protein-derived synthetic polypeptides in mice. These synthetic peptides correspond to the N- and the C-terminal domains 22-125 and 289-390, respectively of the P. falciparum 7G8 isolate CS protein expressed on the sporozoite surface. They comprise what is believed to be the mature protein, except for the central repetitive B cell domain. BALB/c (H-2d) mice were immunized s.c. with 50 micrograms soluble CS polypeptides emulsified in IFA. After a single immunization, CS-specific helper and cytotoxic T lymphocytes (CTLs) could be obtained. The resultant CTLs obtained by in vitro restimulation of primed lymph node (LN) cells recognized H-2Kd target cells in the presence of short synthetic peptides defined in the present study. These epitopes are contained within the N- and C-terminal regions of the CS protein, and correspond to sequences 39-47 and 333-342. In addition, these CTLs can specifically lyse H-2d target cells transfected with the CS gene. These results suggest that, by immunization of mice with large soluble CS synthetic polypeptides in IFA, it is possible to obtain MHC class I-restricted T cell responses specific for the CS protein. This approach might be advantageous in the formulation of efficient malaria subunit vaccines.

Genetic selection system allowing monitoring of myofibrillogenesis in living cardiomyocytes derived from mouse embryonic stem cells

Embryonic stem (ES) cell-derived cardiomyocytes recapitulate cardiomyogenesis in vitro and are a potential source of cells for cardiac repair. However, this requires enrichment of mixed populations of differentiating ES cells into cardiomyocytes. Toward this goal, we have generated bicistronic vectors that express both the blasticidin S deaminase (bsd) gene and a fusion protein consisting of either myosin light chain (MLC)-3f or human alpha-actinin 2A and enhanced green fluorescent protein (EGFP) under the transcriptional control of the alpha-cardiac myosin heavy chain (alpha-MHC) promoter. Insertion of the DNase I-hypersensitive site (HS)-2 element from the beta-globin locus control region, which has been shown to reduce transgene silencing in other cell systems, upstream of the transgene promoter enhanced MLC3f-EGFP gene expression levels in mouse ES cell lines. The alpha-MHC-alpha-actinin-EGFP, but not the alpha-MHC-MLC3f-EGFP, construct resulted in the correct incorporation of the newly synthesized fusion protein at the Z-band of the sarcomeres in ES cell-derived cardiomyocytes. Exposure of embryoid bodies to blasticidin S selected for a relatively pure population of cardiomyocytes within 3 days. Myofibrillogenesis could be monitored by fluorescence microscopy in living cells due to sarcomeric epitope tagging. Therefore, this genetic system permits the rapid selection of a relatively pure population of developing cardiomyocytes from a heterogeneous population of differentiating ES cells, simultaneously allowing monitoring of early myofibrillogenesis in the selected myocytes