Use of ferrets for electrophysiologic monitoring of ion transport.

Limited success achieved in translating basic science discoveries into clinical applications for chronic airway diseases is attributed to differences in respiratory anatomy and physiology, poor approximation of pathologic processes, and lack of correlative clinical endpoints between humans and laboratory animal models. Here, we discuss advantages of using ferrets (Mustela putorus furo) as a model for improved understanding of human airway physiology and demonstrate assays for quantifying airway epithelial ion transport in vivo and ex vivo, and establish air-liquid interface cultures of ferret airway epithelial cells as a complementary in vitro model for mechanistic studies. We present data here that establishes the feasibility of measuring these human disease endpoints in ferrets. Briefly, potential difference across the nasal and the lower airway epithelium in ferrets could be consistently assessed, were highly reproducible, and responsive to experimental interventions. Additionally, ferret airway epithelial cells were amenable to primary cell culture methods for in vitro experiments as was the use of ferret tracheal explants as an ex vivo system for assessing ion transport. The feasibility of conducting multiple assessments of disease outcomes supports the adoption of ferrets as a highly relevant model for research in obstructive airway diseases.

Characterization of defects in ion transport and tissue development in cystic fibrosis transmembrane conductance regulator (CFTR)-knockout rats.

Animal models for cystic fibrosis (CF) have contributed significantly to our understanding of disease pathogenesis. Here we describe development and characterization of the first cystic fibrosis rat, in which the cystic fibrosis transmembrane conductance regulator gene (CFTR) was knocked out using a pair of zinc finger endonucleases (ZFN). The disrupted Cftr gene carries a 16 base pair deletion in exon 3, resulting in loss of CFTR protein expression. Breeding of heterozygous (CFTR+/-) rats resulted in Mendelian distribution of wild-type, heterozygous, and homozygous (CFTR-/-) pups. Nasal potential difference and transepithelial short circuit current measurements established a robust CF bioelectric phenotype, similar in many respects to that seen in CF patients. Young CFTR-/- rats exhibited histological abnormalities in the ileum and increased intracellular mucus in the proximal nasal septa. By six weeks of age, CFTR-/- males lacked the vas deferens bilaterally. Airway surface liquid and periciliary liquid depth were reduced, and submucosal gland size was abnormal in CFTR-/- animals. Use of ZFN based gene disruption successfully generated a CF animal model that recapitulates many aspects of human disease, and may be useful for modeling other CF genotypes, including CFTR processing defects, premature truncation alleles, and channel gating abnormalities.

Quantification, distribution, and possible source of bacterial biofilm in mouse automated watering systems.

The use of automated watering systems for providing drinking water to rodents has become commonplace in the research setting. Little is known regarding bacterial biofilm growth within the water piping attached to the racks (manifolds). The purposes of this project were to determine whether the mouse oral flora contributed to the aerobic bacterial component of the rack biofilm, quantify bacterial growth in rack manifolds over 6 mo, assess our rack sanitation practices, and quantify bacterial biofilm development within sections of the manifold. By using standard methods of bacterial identification, the aerobic oral flora of 8 strains and stocks of mice were determined on their arrival at our animal facility. Ten rack manifolds were sampled before, during, and after sanitation and monthly for 6 mo. Manifolds were evaluated for aerobic bacterial growth by culture on R2A and trypticase soy agar, in addition to bacterial ATP quantification by bioluminescence. In addition, 6 racks were sampled at 32 accessible sites for evaluation of biofilm distribution within the watering manifold. The identified aerobic bacteria in the oral flora were inconsistent with the bacteria from the manifold, suggesting that the mice do not contribute to the biofilm bacteria. Bacterial growth in manifolds increased while they were in service, with exponential growth of the biofilm from months 3 to 6 and a significant decrease after sanitization. Bacterial biofilm distribution was not significantly different across location quartiles of the rack manifold, but bacterial levels differed between the shelf pipe and connecting elbow pipes.

Polycystic and chronic kidney disease in a young degu (Octodon degus).

A young adult (approximately 20 months), 125 g, female degu (Octodon degus) was housed with a male degu for approximately 1.2 years as a breeding pair. The female was multiparous and had weaned its third litter 2 weeks earlier. The degu was reported to the veterinary service for bloody vaginal discharge and a hunched, thin appearance of 1 day's duration. On physical examination, it exhibited cachexia, molting, slight matting of the hair around the eyes, and moderate dehydration. Hematology results included anemia and leukopenia with lymphocytopenia. Biochemical abnormalities included severe azotemia and phosphatemia. Urine specific gravity was 1.016. The condition of this animal prohibited its continued use in the breeding colony, so it was submitted for necropsy. On gross examination, the left kidney measured 10 x 15 mm, had an irregular surface, and was pale and mildly enlarged, consistent with compensatory hypertrophy. The right kidney was small (5 x 8 mm) and cystic. Both adrenal glands appeared mildly enlarged. Histologically, the left kidney had multiple regions with chronic, diffuse interstitial nephritis, and the right kidney was polycystic. There was mild, focal, cortical nodular hyperplasia in the adrenal glands. In the uterus, there was unilateral, locally extensive necrosis of the endometrium. The clinical chemistry results and histopathology findings are supportive of a diagnosis of renal failure secondary to chronic nephritis and polycystic kidney disease. The etiology of the nephritis is unknown. Polycystic kidney disease can be congenital or hereditary in other rodents.