Using animal models, the gut microbiota has been shown to play a critical role in the health and disease of many organ systems. Unfortunately, animal model studies often lack reproducibility when performed at different institutions. Previous studies in our laboratory have shown that the gut microbiota of mice can vary with a number of husbandry factors leading us to speculate that differing environments may alter gut microbiota, which in turn may influence animal model phenotypes. As an extension of these studies, we hypothesized that the shipping of mice from a mouse producer to an institution will result in changes in the type, relative abundance, and functional composition of the gut microbiota. Furthermore, we hypothesized that mice will develop a microbiota unique to the institution and facility in which they are housed. To test these hypotheses, mice of two strains (C57BL/6J and BALB/cJ), two age groups (4 week and 8 week old), and originating from two types of housing (research animal facility under conventional housing and production facilities under maximum barrier housing) were obtained from The Jackson Laboratory. Fecal samples were collected the day prior to shipping, immediately upon arrival, and then on days 2, 5, 7, and weeks 2, 4, and 9 post-arrival. Following the first post-arrival fecal collection, mice were separated into 2 groups and housed at different facilities at our institution while keeping their caging, diet, and husbandry practices the same. DNA was extracted from the collected fecal pellets and 16S rRNA amplicons were sequenced in order to characterize the type and relative abundance of gut bacteria. Principal component analysis (PCA) and permutational multivariate analysis of variance (PERMANOVA) demonstrated that both the shipping and the institution and facility in which mice were housed altered the gut microbiota. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) predicted differences in functional composition in the gut microbiota of mice based on time of acclimation.

With the advent of genetic engineering of rodents came the need to assess fertility and germline competency, especially in chimeric rodents generated using embryonic stem cells. Traditional methods rely on natural mating and progeny testing, which is time- and cost-intensive. Electroejaculation is a faster method of collecting sperm for genetic analysis and offers the additional benefit of using fewer animals. This column describes a refined electroejaculation technique for chimeric rats using light gas anesthesia and a custom-made platform for sperm collection.

Sulfate-reducing bacteria including Desulfovibrio spp. have been associated with suppression of tumor incidence and growth of colorectal cancer (CRC) in human and animal studies. However, other studies suggest that Desulfovibrio spp. are decreased in healthy controls. To address this dichotomy, we treated a rat model of CRC with biofilm-forming and biofilm-deficient strains of Desulfovibrio vulgaris Hildenborough (DvH) to evaluate tumor development. The biofilm-forming DvH stably colonized the rat colon after neonatal administration. Contrarily, the biofilm-deficient strain was undetectable one-week after treatment. The colonic adenoma burden was significantly reduced in the biofilm-forming DvH treated rats compared to the control and biofilm-deficient group. In contrast, known mucin degrading bacteria were increased in the control groups correlating with increased expression of the colonic mucin gene, MUC2, and DNA repair genes MSH2, ATM, and MGMT. This indicates that sulfate reducing biofilm forming bacteria can colonize and protect the colonic epithelium from adenoma initiation.