Production of Transgenic Animals Using Spermatogonial Stem Cells

Spermatogonial stem cells （SSCs） are a type of adult stem cell found in male mammals.These cells have the capacity for self renewal and are capable of differentiating in the niche of testis.They are also the only adult stem cells in a normal postnatal body that undergo self-renewal throughout life,transferring genetic information to the offspring.Since a technique for transplanting SSCs was first described by Brinster and his colleagues in 1994,more and more researchers have become interested in exploring the possibility of utilizing adult SSCs to generate transgenic animals.In this mini-review,we attempt to summarize the current research progress in the area of spermatogonial stem cells including the source,types and differentiation of the SSCs,and the application on transgenic animals,with a particular focus on the strategy of SSCs delivery including seminiferous tubule injection and spermatogonial stem cell transplantation.

Reproductive characteristics of transgenic (TG) chickens caping an exogenous gene

An exogenous gene (lacZ/MiwZ) introduced into the germinal crescent region (GCR) of avian embryos was con-firmed to be successfully transferred to the gonads via the primordial germ cells (PGCs). Following hatching, the chickswere raised until the stage of sexual maturation. The incorporation of MiwZ DNA was detected in male and female trans-genic chickens, respectively. The normal male and female transgenic birds were subjected to artificial insemination ac-cording to routine methods. Fertilized eggs obtained from female transgenic chickens were incubated for 72 h and the em-bryos removed from the yolk were examined by X-gal staining to detect the introduction of MiwZ in the offspring. As aresult, the expression of MiwZ was detected in the offspring. Furthermore, the presence of MiwZ in the extracts fromembryos was also detected by polymerase chain reaction (PCR) analysis. In male transgenic chickens, the presence of in-jected MiwZ in the extracts from sperm was also confirmed. The exogenous gene introduced into the GCR migrated suc-cessfully to the gonad resulting in its incorporation into the offspring and spermatozoa of transgenic chickens. (Asian JAndrol 1999 Sep ; 1: 139 - 144)

Mammalian Models Based on RCAS-TVA Technique

The retroviral vector （RCAS） has been widely used in avian system to study development and diseases, but is not suitable for mammals which do not produce the retrovirus receptor TVA. In this review, we trace the current uses of RCAS-TVA approach in mammalian system with improved strategies, including generation of tv-a transgenic mice, use of soluble TVA receptor and retroviral receptor-ligand fusion proteins, improvement of RCAS vectors, and compare a series of mammalian models in variant studies of gene function, development, oncogenesis and gene therapy. All those studies demonstrate that the RCAS-TVA based mammalian models are powerful tools for understanding the mechanisms and target treating of human diseases.

Genome engineering technologies in rabbits

The rabbit has been recognized as a valuable model in various biomedical and biological research fields because of its intermediate size and phylogenetic proximity to primates.However,the technology for precise genome manipulations in rabbit has been stalled for decades,severely limiting its applications in biomedical research.Novel genome editing technologies,especially CRISPR/Cas9,have remarkably enhanced precise genome manipulation in rabbits,and shown their superiority and promise for generating rabbit models of human genetic diseases.In this review,we summarize the brief history of transgenic rabbit technology and the development of novel genome editing technologies in rabbits.

以新换旧——用独立通风笼盒(IVC)取代弹性薄膜隔离器

In response to the needs for improved standards of bio containment, individual ventilated cages (IVCs) have been developed. These cages provide a protected environment for animals and are of great assistance in containing airborne contaminants. As the number of transgenic animals has increased, IVCs have become more popular because of the possibilities they offer in the prevention of cross contamination and their capability to house small groups of animals of differing sources in close proximity without compromising their health status. This paper will compare IVCs with flexible film isolators. Historically flexible film isolators have been the method of choice for housing animals of a defined health status such as gnotobiotic and germ free animals. The isolator was developed by Trexler and Reyniers during World War Ⅱ for the study of scrub typhus. Today the perception of using isolators for animal housing is still often met with the assumption that isolators are difficult to use and expensive to operate. At B&K Universal Limited we use both isolators and IVCs depending on the particular need. This paper will present a practical comparison of the two methods of containment.

Influence of Species Differences on the Neuropathology of Transgenic Huntington's Disease Animal Models

Transgenic animal models have revealed much about the pathogenesis of age-dependent neurodegenerative diseases and proved to be a useful tool for uncovering therapeutic targets. Huntington＇s disease is a well-characterized neurodegenerative disorder that is caused by expansion of a CAG repeat, which results in expansion of a polyglutamine tract in the N-terminal region of huntingtin （HTT）. Similar CAG/glutamine expansions are also found to cause eight other neurodegenerative diseases that affect distinct brain regions in an age- dependent manner. Identification of this CAG/glutamine expansion has led to the generation of a variety of transgenic animal models. Of these different animal models, transgenic mice have been investigated extensively, and they show similar neuropathology and phenotypes as seen in their respective diseases. The common pathological hallmark of age-dependent neurodegeneration is the formation of aggregates or inclusions consisting of misfolded proteins in the affected brain regions; however, overt or striking neurodegeneration and apoptosis have not been reported in most transgenic mouse models for age-dependent diseases, including HD. By comparing the neuropathology of transgenic HD mouse, pig, and monkey models, we found that mutant HTT is more toxic to larger animals than mice, and larger animals also show neuropathology that has not been uncovered by transgenic mouse models. This review will discuss the importance of transgenic large animal models for analyzing the treatments. pathogenesis of neurodegenerative diseases and developing effective