Temperature-dependent sex determination (TSD) is a well-known characteristic of many reptilian species. However, the molecular processes linking ambient temperature to determination of gonad fate remain hazy. Here, we test the hypothesis that Wnt expression and signaling differ between female- and male-producing temperatures in the snapping turtle <i>Chelydra serpentina</i>. Canonical Wnt signaling involves secretion of glycoproteins called WNTs, which bind to and activate membrane bound receptors that trigger β-catenin stabilization and translocation to the nucleus where β-catenin interacts with TCF/LEF transcription factors to regulate expression of Wnt targets. Non-canonical Wnt signaling occurs via 2 pathways that are independent of β-catenin: one involves intracellular calcium release (the Wnt/Ca²⁺ pathway), while the other involves activation of RAC1, JNK, and RHOA (the Wnt/planar cell polarity pathway). We screened 20 Wnt genes for differential expression between female- and male-producing temperatures during sex determination in the snapping turtle. Exposure of embryos to the female-producing temperature decreased expression of 7 Wnt genes but increased expression of 2 Wnt genes and <i>Rspo1</i> relative to embryos at the male-producing temperature. Temperature also regulated expression of putative Wnt target genes in vivo and a canonical Wnt reporter (6x TCF/LEF sites drive H2B-GFP expression) in embryonic gonadal cells in vitro. Results indicate that Wnt signaling was higher at the female- than at the male-producing temperature. Evolutionary analyses of all 20 Wnt genes revealed that thermosensitive Wnts, as opposed to insensitive Wnts, were less likely to show evidence of positive selection and experienced stronger purifying selection within TSD species.

Background Natural variation in protein expression is common in all organisms and contributes to phenotypic differences among individuals. While variation in gene expression at the transcript level has been extensively investigated, the genetic mechanisms underlying variation in protein expression have lagged considerably behind. Here we investigate genetic architecture of protein expression by profiling a deep mouse brain proteome of two inbred strains, C57BL/6 J (B6) and DBA/2 J (D2), and their reciprocal F1 hybrids using two-dimensional liquid chromatography coupled with tandem mass spectrometry (LC/LC-MS/MS) technology. Results By comparing protein expression levels in the four mouse strains, we observed 329 statistically significant differentially expressed proteins between the two parental strains and characterized the genetic basis of protein expression. We further applied a proteogenomic approach to detect variant peptides and define protein allele-specific expression (pASE), identifying 33 variant peptides with cis-effects and 17 variant peptides showing trans-effects. Comparison of regulation at transcript and protein levels show a significant divergence. Conclusions The results provide a comprehensive analysis of genetic architecture of protein expression and the contribution of cis- and trans-acting regulatory differences to protein expression.

Regulation of the immune response to Salmonella enterica serovar Typhimurium ( S. Typhimurium) infection is a complex process, influenced by the interaction between genetic and environmental factors. Different inbred strains of mice exhibit distinct levels of resistance to S. Typhimurium infection, ranging from susceptible (e.g., C57BL/6J) to resistant (e.g., DBA/2J) strains. However, the underlying molecular mechanisms contributing to the host response remain elusive.

Regulation of the immune response to Salmonella typhimurium (S. Typhimurium) infection is a complex process, influenced by genetic and environmental factors. Different inbred mouse strains show distinct levels of resistance to S. Typhimurium infection, ranging from susceptible (e.g., C57BL/6J) to resistant (e.g., DBA/2J) strains. However, the underlying molecular mechanisms contributing to the host response remain elusive. In this study, we present a comprehensive proteomics profiling of the spleen tissue from C57BL/6J and DBA/2J strains with different doses of S. Typhimurium infection by tandem tag mass coupled with two-dimensional liquid chromatography-tandem mass spectrometry. We identified and quantified 3,986 proteins, resulting in 475 differentially expressed proteins between C57BL/6J and DBA/2J strains. Functional enrichment analysis revealed that the mechanisms of innate immune responses to S. Typhimurium infection are associated with several signaling pathways, including the interferon signaling pathway. Our proteomic data also discovered a plausible gene in a genomic region that control different levels of resistance to S. Typhimurium infection. We further revealed the roles of macrophage cells and pro-inflammatory cytokines in the mechanisms under the natural resistance to S. Typhimurium. In summary, our results provide new insights into the genetic regulation of the immune response to S. Typhimurium infection in mice.Author SummarySalmonella infection (salmonellosis) is a common zoonotic disease that mainly propagates through contaminated food and drink. Various mouse strains display prominent disparities in responses to Salmonella invasion. Elucidating the heterogeneous immune reactions between different mouse strains can shed light on the fundamental molecular mechanisms of the innate immune system. Here, we employed a combination of proteomics and systems biology approaches to provide an unprecedented panorama of the inextricably interlaced immune signaling pathways in response to Salmonella infection in mice. Our results revealed the dynamics of cell signaling molecules elicited by inflammation and established new connections among them. We also identified a new candidate gene involved in the combat with pathogens. Our proteomic data and results contribute to understanding the intricate interactions of immune responses to Salmonella infection from molecular to systemic levels.