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Abstract Background Engineered zinc-finger nucleases (ZFN) represented an innovative method for the genome manipulation in vertebrates. ZFN introduced targeted DNA double strand breaks (DSB) and initiated non-homologous end joining (NHEJ) after pronuclear or cytoplasmatic microinjection into zygotes. Resulting frame shift mutations led to functional gene ablations in zebra fish, mice, pigs and also in laboratory rats. Therefore, we targeted the rat Rag1 gene essential for the V(D)J recombination within the immunoglobulin production process and for the differentiation of mature B and T lymphocytes to generate an immunodeficient rat model in the LEW/Ztm strain. Results After microinjection of Rag1 specific ZFN mRNAs in 623 zygotes of inbred LEW/Ztm rats 59 offspring were born from which one carried a 4 bp deletion. This frame shift mutation led to a premature stop codon and a subsequently truncated Rag1 protein confirmed by the loss of the full-length protein in Western Blot analysis. Truncation of the Rag1 protein was characterized by the complete depletion of mature B cells. The remaining T cell population contained mature CD4+/CD3+/TCRαβ+ as well as CD8+/CD3+/TCRαβ+ positive lymphocytes accompanied by a compensatory increase of natural killer cells in the peripheral blood. Reduction of T cell development in Rag1 mutant rats was associated with a hypoplastic thymus that lacked follicular structures. Histological evaluation also revealed the near-complete absence of lymphocytes in spleen and lymph nodes in the immunodeficient Rag1 mutant rat. Conclusion The Rag1 mutant rat will serve as an important model for transplantation studies. Furthermore, it may be used as a model for reconstitution experiments related to the immune system, particularly with respect to different populations of human lymphocytes, natural killer cells and autoimmune phenomena.

Abstract Background Since the discovery of the human CFTR gene in 1989 various mouse models for cystic fibrosis (CF) have been generated and used as a very suitable and popular tool to approach research on this life-threatening disease. Age related changes regarding the course of disease and susceptibility towards pulmonary infections have been discussed in numerous studies. Methods Here, we investigated CftrTgH(neoim)Hgu and Cftrtm1Unc-Tg(FABPCFTR)1Jaw/J CF mice and their non-CF littermates during an acute lung infection with Pseudomonas aeruginosa for age dependent effects of their lung function and immune response. Mice younger than three or older than six months were intratracheally infected with P. aeruginosa TBCF10839. The infection was monitored by lung function of the animals using non-invasive head-out spirometry and the time course of physiological parameters over 192 hours. Quantitative bacteriology and lung histopathology of a subgroup of animals were used as endpoint parameters. Results Age-dependent changes in lung function and characteristic features for CF like a shallower, faster breathing pattern were observed in both CF mouse models in uninfected state. In contrast infected CF mice did not significantly differ from their non-CF littermates in susceptibility and severity of lung infection in both mouse models and age groups. The transgenic Cftrtm1Unc-Tg(FABPCFTR)1Jaw/J and their non-CF littermates showed a milder course of infection than the CftrTgH(neoim)Hgu CF and their congenic C57Bl/6J non-CF mice suggesting that the genetic background was more important for outcome than Cftr dysfunction. Conclusions Previous investigations of the same mouse lines have shown a higher airway susceptibility of older CF mice to intranasally applied P. aeruginosa. The different outcome of intranasal and intratracheal instillation of bacteria implies that infected CF epithelium is impaired during the initial colonization of upper airways, but not in the subsequent response of host defense.

Abstract Background A major boost to cystic fibrosis disease research was given by the generation of various mouse models using gene targeting in embryonal stem cells. Moreover, the introduction of the same mutation on different inbred strains generating congenic strains facilitated the search for modifier genes. From the original CftrTgH(neoim)Hgu mouse model with a divergent genetic background (129/Sv, C57BL/6, HsdOla:MF1) two inbred mutant mouse strains CF/1-CftrTgH(neoim)Hgu and CF/3-CftrTgH(neoim)Hgu had been generated using strict brother × sister mating. CF/1-CftrTgH(neoim)Hgu and CF/3-CftrTgH(neoim)Hgu mice were fertile and showed normal growth and lifespan. In this work the CftrTgH(neoim)Hgu insertional mutation was backcrossed from CF/3-CftrTgH(neoim)Hgu onto the inbred backgrounds C57BL/6J and DBA/2J generating congenic animals in order to clarify the differential impact of the Cftr mutation and the genetic background on the disease phenotype of the cystic fibrosis mutant mice. Clinical and electrophysiological features of the two congenic strains were compared with those of CF/1-CftrTgH(neoim)Hgu and CF/3-CftrTgH(neoim)Hgu and wild type controls. Results Under the standardized housing conditions of the animal facility, the four mouse strains CF/1-CftrTgH(neoim)Hgu, CF/3-CftrTgH(neoim)Hgu, D2.129P2(CF/3)-CftrTgH(neoim)Hgu and B6.129P2(CF/3)-CftrTgH(neoim)Hgu exhibited normal life expectancy. Growth of congenic cystic fibrosis mice was comparable with that of wild type controls. All mice but D2.129P2(CF/3)-CftrTgH(neoim)Hgu females were fertile. Short circuit current measurements revealed characteristic response profiles of the HsdOla:MF1, DBA/2J and C57BL/6J backgrounds in nose, ileum and colon. All cystic fibrosis mouse lines showed the disease-typical hyperresponsiveness to amiloride in the respiratory epithelium. The mean chloride secretory responses to carbachol or forskolin were 15–100% of those of the cognate wild type control animals. Conclusion The amelioration of the clinical features and of the basic defect that had emerged during the generation of CF/3-CftrTgH(neoim)Hgu mice was retained in the congenic mice indicating that the Cftr linkage group or other loci shared between the inbred strains contain(s) the major modifier(s) of attenuation of cystic fibrosis symptoms.

Abstract Background The laboratory rat (Rattus norvegicus) is an important model for studying many aspects of human health and disease. Detailed knowledge on genetic variation between strains is important from a biomedical, particularly pharmacogenetic point of view and useful for marker selection for genetic cloning and association studies. Results We show that Single Nucleotide Polymorphisms (SNPs) in commonly used rat strains are surprisingly well represented in wild rat isolates. Shotgun sequencing of 814 Kbp in one wild rat resulted in the identification of 485 SNPs as compared with the Brown Norway genome sequence. Genotyping 36 commonly used inbred rat strains showed that 84% of these alleles are also polymorphic in a representative set of laboratory rat strains. Conclusion We postulate that shotgun sequencing in a wild rat sample and subsequent genotyping in multiple laboratory or domesticated strains rather than direct shotgun sequencing of multiple strains, could be the most efficient SNP discovery approach. For the rat, laboratory strains still harbor a large portion of the haplotypes present in wild isolates, suggesting a relatively recent common origin and supporting the idea that rat inbred strains, in contrast to mouse inbred strains, originate from a single species, R. norvegicus.

Genetic quality assurance (QA), including genetic monitoring (GeMo) of inbred strains and background characterization (BC) of genetically altered (GA) animal models, should be an essential component of any QA programme in laboratory animal facilities. Genetic quality control is as important for ensuring the validity of the animal model as health and microbiology monitoring are. It should be required that studies using laboratory rodents, mainly mice and rats, utilize genetically defined animals. This paper, presented by the FELASA Working Group on Genetic Quality Assurance and Genetic Monitoring of Laboratory Murines, describes the objectives of and available methods for genetic QA programmes in rodent facilities. The main goals of any genetic QA programme are: (a) to verify the authenticity and uniformity of inbred stains and substrains, thus ensuring a genetically reliable colony maintenance; (b) to detect possible genetic contamination; and (c) to precisely describe the genetic composition of GA lines. While this publication focuses mainly on mouse and rat genetic QA, the principles will apply to other rodent species some of which are briefly mentioned within the context of inbred and outbred stocks. [ABSTRACT FROM AUTHOR]

The laboratory mouse is the most used animal model in biomedical research. Several artificial reproductive techniques, such as revitalization of cryopreserved strains, rederivation after hygienic contaminations and the production of transgenic mouse models, require the transfer of preimplantation embryos to surrogate mothers. Pseudopregnancy is essential in recipient females and is induced by mating with sterile males. Commonly, surgically vasectomized males are used for this purpose. As an alternative, genetically modified mouse strains have been identified, in which homozygous infertile males are sexually active. Here, we investigated the suitability of genetically infertile Gapdhstm1Dao males under routine laboratory conditions with respect to plug rates, pregnancy rates and frequency of born offspring after embryo transfer. Our results showed no significant differences for these aspects between Gapdhstm1Dao and vasectomized CD2F1 males. In addition, we evaluated the efforts to obtain a defined number of sterile males either by breeding of sterile mutants or surgical vasectomy, and addressed the impact of both options on animal welfare. In conclusion, infertile males of the Gapdhstm1Dao line are a reliable alternative to vasectomized males for the induction of pseudopregnancy, and can contribute to the refinement of the procedure by avoiding surgical interventions. [ABSTRACT FROM AUTHOR]