Mouse phenogenomics, toolbox for functional annotation of human genome

Mouse models of sarcopenia: classification and evaluation

Sarcopenia is a progressive and widespread skeletal muscle disease that is related to an increased possibility of adverse consequences such as falls, fractures, physical disabilities and death, and its risk increases with age. With the deepening of the understanding of sarcopenia, the disease has become a major clinical disease of the elderly and a key challenge of healthy ageing. However, the exact molecular mechanism of this disease is still unclear, and the selection of treatment strategies and the evaluation of its effect are not the same. Most importantly, the early symptoms of this disease are not obvious and are easy to ignore. In addition, the clinical manifestations of each patient are not exactly the same, which makes it difficult to effectively study the progression of sarcopenia. Therefore, it is necessary to develop and use animal models to understand the pathophysiology of sarcopenia and develop therapeutic strategies. This paper reviews the mouse models that can be used in the study of sarcopenia, including ageing models, genetically engineered models, hindlimb suspension models, chemical induction models, denervation models, and immobilization models; analyses their advantages and disadvantages and application scope; and finally summarizes the evaluation of sarcopenia in mouse models.

Ensuring reproducibility and ethics in animal experiments reporting in Korea using the ARRIVE guideline

The aim of this study is to evaluate the reporting quality of animal experiments in Korea using the Animals in Research: Reporting In Vivo Experiments (ARRIVE) guideline developed in 2010 to overcome the reproducibility problem and to encourage compliance with replacement, refinement and reduction of animals in research (3R's principle). We reviewed 50 papers published by a Korean research group from 2013 to 2016 and scored the conformity with the 20-items ARRIVE guideline. The median conformity score was 39.50%. For more precise evaluation, the 20 items were subdivided into 57 sub-items. Among the sub-items, status of experimental animals, housing and husbandry were described under the average level. Microenvironment sub-items, such as enrichment, bedding material, cage type, number of companions, scored under 10%. Although statistical methods used for the studies were given in most publications (84%), sample size calculation and statistical assumption were rarely described. Most publications mentioned the IACUC approval, but only 8% mentioned welfare-related assessments and interventions, and only 4% mentioned any implications of experimental methods or findings for 3R. We may recommend the revision of the present IACUC proposal to collect more detailed information and improving educational program for animal researchers according to the ARRIVE guideline.

Hairy and Enhancer of Split 6 (Hes6) Deficiency in Mouse Impairs Neuroblast Differentiation in Dentate Gyrus Without Affecting Cell Proliferation and Integration into Mature Neurons

Hes6 is a member of the hairy-enhancer of split homolog (Hes) family of transcription factors and interacts with other Hes family genes. During development, Hes genes are expressed in neural stem cells and progenitor cells. However, the role of Hes6 in adult hippocampal neurogenesis remains unclear. We therefore investigated the effects of Hes6 on adult hippocampal neurogenesis, by comparing Hes6 knockout and wild-type mice. To this end, we immunostained for markers of neural stem cells and progenitor cells (nestin), proliferating cells (Ki67), post-mitotic neuroblasts and immature neurons (doublecortin, DCX), mature neuronal cells (NeuN), and astrocyte (S100β). We also injected 5-bromo-2'-deoxyuridine (BrdU) to trace the fate of mitotic cells. Nestin- and Ki67-positive proliferating cells did now show any significant differences between wild and knockout groups. Hes6 knockout negatively affects neuroblast differentiation based on DCX immunohistochemistry. On the contrary, the ratio of the BrdU and NeuN double-positive cells did not show any significance, even though it was slightly higher in the knockout group. These results suggest that Hes6 is involved in the regulation of neuroblast differentiation during adult neurogenesis, but does not influence integration into mature neurons.

Animal models of contraception: utility and limitations

Appropriate animal modeling is vital for the successful development of novel contraceptive devices. Advances in reproductive biology have identified novel pathways for contraceptive intervention. Here we review species-specific anatomic and physiologic considerations impacting preclinical contraceptive testing, including efficacy testing, mechanistic studies, device design, and modeling off-target effects. Emphasis is placed on the use of nonhuman primate models in contraceptive device development.

Histopathology reveals correlative and unique phenotypes in a high-throughput mouse phenotyping screen

The Mouse Genetics Project (MGP) at the Wellcome Trust Sanger Institute aims to generate and phenotype over 800 genetically modified mouse lines over the next 5 years to gain a better understanding of mammalian gene function and provide an invaluable resource to the scientific community for follow-up studies. Phenotyping includes the generation of a standardized biobank of paraffin-embedded tissues for each mouse line, but histopathology is not routinely performed. In collaboration with the Pathology Core of the Centre for Modeling Human Disease (CMHD) we report the utility of histopathology in a high-throughput primary phenotyping screen. Histopathology was assessed in an unbiased selection of 50 mouse lines with (n=30) or without (n=20) clinical phenotypes detected by the standard MGP primary phenotyping screen. Our findings revealed that histopathology added correlating morphological data in 19 of 30 lines (63.3%) in which the primary screen detected a phenotype. In addition, seven of the 50 lines (14%) presented significant histopathology findings that were not associated with or predicted by the standard primary screen. Three of these seven lines had no clinical phenotype detected by the standard primary screen. Incidental and strain-associated background lesions were present in all mutant lines with good concordance to wild-type controls. These findings demonstrate the complementary and unique contribution of histopathology to high-throughput primary phenotyping of mutant mice.

Mouse genetics: catalogue and scissors

Phenotypic analysis of gene-specific knockout (KO) mice has revolutionized our understanding of in vivo gene functions. As the use of mouse embryonic stem (ES) cells is inevitable for conventional gene targeting, the generation of knockout mice remains a very time-consuming and expensive process. To accelerate the large-scale production and phenotype analyses of KO mice, international efforts have organized global consortia such as the International Knockout Mouse Consortium (IKMC) and International Mouse Phenotype Consortium (IMPC), and they are persistently expanding the KO mouse catalogue that is publicly available for the researches studying specific genes of interests in vivo. However, new technologies, adopting zinc-finger nucleases (ZFNs) or Transcription Activator-Like Effector (TALE) Nucleases (TALENs) to edit the mouse genome, are now emerging as valuable and effective shortcuts alternative for the conventional gene targeting using ES cells. Here, we introduce the recent achievement of IKMC, and evaluate the significance of ZFN/TALEN technology in mouse genetics.

Optical coherence tomography for live phenotypic analysis of embryonic ocular structures in mouse models

Mouse models of ocular diseases provide a powerful resource for exploration of molecular regulation of eye development and pre-clinical studies. Availability of a live high-resolution imaging method for mouse embryonic eyes would significantly enhance longitudinal analyses and high-throughput morphological screening. We demonstrate that optical coherence tomography (OCT) can be used for live embryonic ocular imaging throughout gestation. At all studied stages, the whole eye is within the imaging distance of the system and there is a good optical contrast between the structures. We also performed OCT eye imaging in the embryonic retinoblastoma mouse model Pax6-SV40 T-antigen, which spontaneously forms lens and retinal lesions, and demonstrate that OCT allows us to clearly differentiate between the mutant and wild type phenotypes. These results demonstrate that OCTin utero imaging is a potentially useful tool to study embryonic ocular diseases in mouse models.

3-dimensional imaging modalities for phenotyping genetically engineered mice

A variety of 3-dimensional (3D) digital imaging modalities are available for whole-body assessment of genetically engineered mice: magnetic resonance microscopy (MRM), X-ray microcomputed tomography (microCT), optical projection tomography (OPT), episcopic and cryoimaging, and ultrasound biomicroscopy (UBM). Embryo and adult mouse phenotyping can be accomplished at microscopy or near microscopy spatial resolutions using these modalities. MRM and microCT are particularly well-suited for evaluating structural information at the organ level, whereas episcopic and OPT imaging provide structural and functional information from molecular fluorescence imaging at the cellular level. UBM can be used to monitor embryonic development longitudinally in utero. Specimens are not significantly altered during preparation, and structures can be viewed in their native orientations. Technologies for rapid automated data acquisition and high-throughput phenotyping have been developed and continually improve as this exciting field evolves.

Optical Coherence Tomography for live imaging of mammalian development

Understanding the nature and mechanism of congenital defects of the different organ systems in humans has heavily relied on the analysis of the corresponding mutant phenotypes in rodent models. Optical Coherence Tomography (OCT) has recently emerged as a powerful tool to study early embryonic development. This non-invasive optical methodology does not require labeling and allows visualization of embryonic tissues with single cell resolution. Here, we will discuss how OCT can be applied for structural imaging of early mouse and rat embryos in static culture, cardiodynamic and blood flow analysis, and in utero embryonic imaging at later stages of gestation, demonstrating how OCT can be used to assess structural and functional birth defects in mammalian models.

Internet and Print Resources to Facilitate Pathology Analysis When Phenotyping Genetically Engineered Rodents

Genetically engineered mice and rats are increasingly used as models for exploring disease progression and mechanisms. The full spectrum of anatomic, biochemical, and functional changes that develop in novel, genetically engineered mouse and rat lines must be cataloged before predictions regarding the significance of the mutation may be extrapolated to diseases in other vertebrate species, including humans. A growing list of reference materials, including books, journal articles, and websites, has been produced in the last 2 decades to assist researchers in phenotyping newly engineered rodent lines. This compilation provides an extensive register of materials related to the pathology component of rodent phenotypic analysis. In this article, the authors annotate the resources they use most often, to allow for quick determination of their relevance to research projects.

Optical coherence tomography for high-resolution imaging of mouse development in utero

Although the mouse is a superior model to study mammalian embryonic development, high-resolution live dynamic visualization of mouse embryos remain a technical challenge. We present optical coherence tomography as a novel methodology for live imaging of mouse embryos through the uterine wall thereby allowing for time lapse analysis of developmental processes and direct phenotypic analysis of developing embryos. We assessed the capability of the proposed methodology to visualize structures of the living embryo from embryonic stages 12.5 to 18.5 days postcoitus. Repetitive in utero embryonic imaging is demonstrated. Our work opens the door for a wide range of live, in utero embryonic studies to screen for mutations and understand the effects of pharmacological and toxicological agents leading to birth defects.