Project description:In a single-cell RNA sequencing experiment, we defined subsets of intestinal epithelial cells in 5-day-old mice and observed decreased transcript levels of sodium-hydrogen exchanger 3 (Nhe3) and Dra in several epithelial cell groups following rotavirus infection. In contrast, transcript levels of sodium-glucose cotransporter 1 (Sglt1), electrogenic sodium bicarbonate cotransporter (Nbce1), solute carrier family 12 member 2 (Nkcc1), and Cftr were unaffected. Furthermore, expression of Nhe3 and Dra was down-regulated in both rotavirus infected intestinal epithelial cells that contained rotavirus transcripts and uninfected bystander cells, suggesting induction of paracrine signaling.
Project description:The electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), is the major bicarbonate transporter expressed in astrocytes. It is highly sensitive for bicarbonate, and the main regulator of intracellular-, extracellular-, and synaptic pH, thereby modulating neuronal excitability. However, despite these essential functions, the molecular mechanisms underlying NBCe1-mediated astrocytic response to extracellular pH changes are mostly unknown. Using primary cortical astrocyte cultures we have investigated the effect of long-term extracellular metabolic alkalosis on regulation of NBCe1 using functional assays and phosphoproteomic analysis.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:A mathematical model of the pancreatic duct cell generating high bicarbonate concentrations in pancreatic juice
David C Whitcomb, G Bard Ermentrout, Pancreas 2004 29:e30-40; PubMedID:15257112
Abstract:
OBJECTIVE:
To develop a simple, physiologically based mathematical model of pancreatic duct cell secretion using experimentally derived parameters that generates pancreatic fluid bicarbonate concentrations of >140 mM after CFTR activation.
METHODS:
A new mathematical model was developed simulating a duct cell within a proximal pancreatic duct and included a sodium-2-bicarbonate cotransporter (NBC) and sodium-potassium pump (NaK pump) on a chloride-impermeable basolateral membrane, CFTR on the luminal membrane with 0.2 to 1 bicarbonate to chloride permeability ratio. Chloride-bicarbonate antiporters (Cl/HCO3 AP) were added or subtracted from the basolateral (APb) and luminal (APl) membranes. The model was integrated over time using XPPAUT.
RESULTS:
This model predicts robust, NaK pump-dependent bicarbonate secretion with opening of the CFTR, generates and maintains pancreatic fluid secretion with bicarbonate concentrations >140 mM, and returns to basal levels with CFTR closure. Limiting CFTR permeability to bicarbonate, as seen in some CFTR mutations, markedly inhibited pancreatic bicarbonate and fluid secretion.
CONCLUSIONS:
A simple CFTR-dependent duct cell model can explain active, high-volume, high-concentration bicarbonate secretion in pancreatic juice that reproduces the experimental findings. This model may also provide insight into why CFTR mutations that predominantly affect bicarbonate permeability predispose to pancreatic dysfunction in humans.
This SBML version of the model was created directly from the XPPAUT code found in the appendix with the exception of the parameter vr, the ratio between the duct cell volume and the duct lumen, which is defined inversely to the main text in the XPPAUT code. vr was defined as the ratio of the duct cell volume to the duct lumen volume as in the main text. The model reproduces the figures found in the article. The model uses initial assignments for the lumen volume and events to trigger CFTR opening, so only tools supporting these features can be used to simulate it (eg. Copasi and SBW/Roadrunner).
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:BackgroundCopy number variation is an important dimension of genetic diversity and has implications in development and disease. As an important model organism, the mouse is a prime candidate for copy number variant (CNV) characterization, but this has yet to be completed for a large sample size. Here we report CNV analysis of publicly available, high-density microarray data files for 351 mouse tail samples, including 290 mice that had not been characterized for CNVs previously.ResultsWe found 9634 putative autosomal CNVs across the samples affecting 6.87% of the mouse reference genome. We find significant differences in the degree of CNV uniqueness (single sample occurrence) and the nature of CNV-gene overlap between wild-caught mice and classical laboratory strains. CNV-gene overlap was associated with lipid metabolism, pheromone response and olfaction compared to immunity, carbohydrate metabolism and amino-acid metabolism for wild-caught mice and classical laboratory strains, respectively. Using two subspecies of wild-caught Mus musculus, we identified putative CNVs unique to those subspecies and show this diversity is better captured by wild-derived laboratory strains than by the classical laboratory strains. A total of 9 genic copy number variable regions (CNVRs) were selected for experimental confirmation by droplet digital PCR (ddPCR).ConclusionThe analysis we present is a comprehensive, genome-wide analysis of CNVs in Mus musculus, which increases the number of known variants in the species and will accelerate the identification of novel variants in future studies.
Project description:BackgroundLong terminal repeat (LTR) retrotransposons make up a large fraction of the typical mammalian genome. They comprise about 8% of the human genome and approximately 10% of the mouse genome. On account of their abundance, LTR retrotransposons are believed to hold major significance for genome structure and function. Recent advances in genome sequencing of a variety of model organisms has provided an unprecedented opportunity to evaluate better the diversity of LTR retrotransposons resident in eukaryotic genomes.ResultsUsing a new data-mining program, LTR_STRUC, in conjunction with conventional techniques, we have mined the GenBank mouse (Mus musculus) database and the more complete Ensembl mouse dataset for LTR retrotransposons. We report here that the M. musculus genome contains at least 21 separate families of LTR retrotransposons; 13 of these families are described here for the first time.ConclusionsAll families of mouse LTR retrotransposons are members of the gypsy-like superfamily of retroviral-like elements. Several different families of unrelated non-autonomous elements were identified, suggesting that the evolution of non-autonomy may be a common event. High sequence similarity between several LTR retrotransposons identified in this study and those found in distantly-related species suggests that horizontal transfer has been a significant factor in the evolution of mouse LTR retrotransposons.
Project description:Here we report the expansion of the genetic code of Mus musculus with various unnatural amino acids including Nɛ-acetyl-lysine. Stable integration of transgenes encoding an engineered Nɛ-acetyl-lysyl-tRNA synthetase (AcKRS)/tRNAPyl pair into the mouse genome enables site-specific incorporation of unnatural amino acids into a target protein in response to the amber codon. We demonstrate temporal and spatial control of protein acetylation in various organs of the transgenic mouse using a recombinant green fluorescent protein (GFPuv) as a model protein. This strategy will provide a powerful tool for systematic in vivo study of cellular proteins in the most commonly used mammalian model organism for human physiology and disease.
Project description:House mice (Mus musculus) emit ultrasonic vocalizations (USVs), which are surprisingly complex and have features of bird song, but their functions are not well understood. Previous studies have reported mixed evidence on whether there are sex differences in USV emission, though vocalization rate or other features may depend upon whether potential receivers are of the same or opposite sex. We recorded the USVs of wild-derived adult house mice (F1 of wild-caught Mus musculus musculus), and we compared the vocalizations of males and females in response to a stimulus mouse of the same- or opposite-sex. To detect and quantify vocalizations, we used an algorithm that automatically detects USVs (Automatic Mouse Ultrasound Detector or A-MUD). We found high individual variation in USV emission rates (4 to 2083 elements/10 min trial) and a skewed distribution, with most mice (60%) emitting few (≤50) elements. We found no differences in the rates of calling between the sexes overall, but mice of both sexes emitted vocalizations at a higher rate and higher frequencies during opposite- compared to same-sex interactions. We also observed a trend toward higher amplitudes by males when presented with a male compared to a female stimulus. Our results suggest that mice modulate the rate and frequency of vocalizations depending upon the sex of potential receivers.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility. Gene expression was measured in whole testis from males aged 62-86 days. Samples include 190 first generation lab-bred male offspring of wild-caught mice from the Mus musculus musculus - M. m. domesticus hybrid zone.