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:A LINE-1 element, LIC105, was found in the Mus musculus domesticus inbred strain, C57BL/6J. Upon sequencing, this element was found to belong to a M. spretus LINE-1 subfamily originating within the last 0.2 million years. This is the second spretus-specific LINE-1 subfamily found to be represented in C57BL/6J. Although it is unclear how these M. spretus LINE-1s transferred from M. spretus to M. m. domesticus, it is now clear that at least two different spretus LINE-1 sequences have recently transferred. The limited divergence between the C57BL/6J spretus-like LINE-1s and their closest spretus ancestors suggests that the transfer did not involve an exceptionally long lineage of sequential transpositions.
Project description:Increased fat intake is associated with obesity and insulin resistance. In some individuals, a failure of pancreatic b-cells to increase insulin production in response to the high demands of obesity leads to diabetes. We sought to determine whether the impaired b- cell adaptation in obesity is associated with differential expression of genes involved in b-cell expansion and intermediary metabolism. Two strains of inbred mice prone to obesity, C57Bl/6J and AKR/J, were fed regular rodent chow or high-fat diet, after which islet morphology, secretory function and gene expression were assessed. AKR/J had lower blood glucose and higher insulin levels compared with C57Bl/6J mice on regular rodent chow or high fat diet. Insulin secretion was 3.2 fold higher in AKR/J than C57Bl/6J mice following intraperitoneal glucose injection. Likewise, glucose-stimulated insulin secretion from isolated islets was higher in AKR/J. Additionally, islet mass was 1.4 fold greater in AKR/J compared with C57Bl/6J. To elucidate the factors associated with the differences in insulin, we analyzed the gene expression profiles in pancreatic islets in AKR/J and C57Bl/6J mice. Of 14,000 genes examined, 220 were up-regulated and 286 were down-regulated in islets from diet-induced obese AKR/J mice compared with C57Bl/6J mice. Key genes involved in islet signaling and metabolism, e.g. glucagon like peptide-1 receptor, sterol Co-A desaturase 1 & 2 and fatty acid desaturase 2 were upregulated in obese AKR/J mice. The expression of multiple extracellular matrix proteins was also increased in AKR/J mice, suggesting a role in modulation of islet mass. Functional analyses of differentially regulated genes hold promise for elucidating factors linking obesity to alterations in islet function. Experiment Overall Design: Microarray analyses were performed on quadruplicate RNA samples of pancreatic islets from AKR and Bl6 mice placed on high-fat diet for 3 months. Pancreases from two mice were combined to yield one sample of islet RNA. All protocols were conducted as described in the Affymetrix GeneChips Expression Analysis Technical Manual (Affymetrix, Santa Clara, CA) using 5 μg total RNA and GeneChip Mouse Expression Arrays MOE 430 (Affymetrix).
Project description:Increased fat intake is associated with obesity and insulin resistance. In some individuals, a failure of pancreatic b-cells to increase insulin production in response to the high demands of obesity leads to diabetes. We sought to determine whether the impaired b- cell adaptation in obesity is associated with differential expression of genes involved in b-cell expansion and intermediary metabolism. Two strains of inbred mice prone to obesity, C57Bl/6J and AKR/J, were fed regular rodent chow or high-fat diet, after which islet morphology, secretory function and gene expression were assessed. AKR/J had lower blood glucose and higher insulin levels compared with C57Bl/6J mice on regular rodent chow or high fat diet. Insulin secretion was 3.2 fold higher in AKR/J than C57Bl/6J mice following intraperitoneal glucose injection. Likewise, glucose-stimulated insulin secretion from isolated islets was higher in AKR/J. Additionally, islet mass was 1.4 fold greater in AKR/J compared with C57Bl/6J. To elucidate the factors associated with the differences in insulin, we analyzed the gene expression profiles in pancreatic islets in AKR/J and C57Bl/6J mice. Of 14,000 genes examined, 220 were up-regulated and 286 were down-regulated in islets from diet-induced obese AKR/J mice compared with C57Bl/6J mice. Key genes involved in islet signaling and metabolism, e.g. glucagon like peptide-1 receptor, sterol Co-A desaturase 1 & 2 and fatty acid desaturase 2 were upregulated in obese AKR/J mice. The expression of multiple extracellular matrix proteins was also increased in AKR/J mice, suggesting a role in modulation of islet mass. Functional analyses of differentially regulated genes hold promise for elucidating factors linking obesity to alterations in islet function. Keywords: response to high fat diet
Project description:MSM/Ms is an inbred strain derived from the Japanese wild mouse, Mus musculus molossinus. It is believed that subspecies molossinus has contributed substantially to the genome constitution of common laboratory strains of mice, although the majority of their genome is derived from the west European M. m. domesticus. Information on the molossinus genome is thus essential not only for genetic studies involving molossinus but also for characterization of common laboratory strains. Here, we report the construction of an arrayed bacterial artificial chromosome (BAC) library from male MSM/Ms genomic DNA, covering approximately 1x genome equivalent. Both ends of 176,256 BAC clone inserts were sequenced, and 62,988 BAC-end sequence (BES) pairs were mapped onto the C57BL/6J genome (NCBI mouse Build 30), covering 2,228,164 kbp or 89% of the total genome. Taking advantage of the BES map data, we established a computer-based clone screening system. Comparison of the MSM/Ms and C57BL/6J sequences revealed 489,200 candidate single nucleotide polymorphisms (SNPs) in 51,137,941 bp sequenced. The overall nucleotide substitution rate was as high as 0.0096. The distribution of SNPs along the C57BL/6J genome was not uniform: The majority of the genome showed a high SNP rate, and only 5.2% of the genome showed an extremely low SNP rate (percentage identity = 0.9997); these sequences are likely derived from the molossinus genome.
Project description:Background: Survival and function of insulin-secreting pancreatic β-cells are markedly altered by changes in nutrient availability. In vitro, culture in 10 rather than 2mM glucose improves rodent β-cell survival and function whereas glucose concentrations above 10mM are deleterious. Aim-Method: To identify the mechanisms of such β-cell plasticity, we tested the effects of a 18h culture at 2, 5, 10 and 30mM glucose on the transcriptome of rat islets precultured for 1 week at 10mM glucose (Affymetrix Rat 230.2 arrays). Results: Culture in either 2-5mM or 30mM instead of 10mM glucose markedly impaired β-cell function without affecting islet cell survival. Of ~16000 probe sets reliably detected in islets, ~5000 were significantly regulated at least 1.4-fold by glucose. Analysis of these probe sets with GeneCluster software identified 10 mRNA profiles with unidirectional up- or down-regulation between 2 and 10, 2 and 30, 5 and 10, 5 and 30 or 10 and 30 mM glucose, and 8 complex V-shaped or inverse V-shaped profiles with a nadir or peak level of expression in 5 or 10mM glucose. Analysis of genes belonging to these various clusters with Onto-express and GenMapp software revealed several signaling and metabolic pathways that may contribute to the induction of β-cell dysfunction and apoptosis after culture in low or high vs. intermediate glucose concentration. Conclusion: We have identified 18 distinct mRNA profiles of glucose-induced changes in islet gene mRNA levels that should help understanding the mechanisms by which glucose affects β-cell survival and function under states of chronic hypo- or hyperglycemia. Experiment Overall Design: Effect of 18h culture in 2, 5, 10 and 30 mmol/l glucose on the transcriptome of rat pancreatic islets precultured for 1 week in 10 mmol/l glucose. Four experiments were done on different islet preparations over a two-months period.