Commercial applications of nuclear transfer cloning: three examples

Generation of antibody- and B cell-deficient pigs by targeted disruption of the J-region gene segment of the heavy chain locus

A poly(A)-trap gene targeting strategy was used to disrupt the single functional heavy chain (HC) joining region (J_H) of swine in primary fibroblasts. Genetically modified piglets were then generated via somatic cell nuclear transfer (SCNT) and bred to yield litters comprising J_H wild-type littermate (+/+), J_H heterozygous knockout (±) and J_H homozygous knockout (−/−) piglets in the expected Mendelian ratio of 1:2:1. There are only two other targeted loci previously published in swine, and this is the first successful poly(A)-trap strategy ever published in a livestock species. In either blood or secondary lymphoid tissues, flow cytometry, RT-PCR and ELISA detected no circulating IgM⁺ B cells, and no transcription or secretion of immunoglobulin (Ig) isotypes, respectively in J_H −/− pigs. Histochemical and immunohistochemical (IHC) studies failed to detect lymph node (LN) follicles or CD79α⁺ B cells, respectively in J_H −/− pigs. T cell receptor (TCR)_β transcription and T cells were detected in J_H −/− pigs. When reared conventionally, J_H −/− pigs succumbed to bacterial infections after weaning. These antibody (Ab)- and B cell-deficient pigs have significant value as models for both veterinary and human research to discriminate cellular and humoral protective immunity to infectious agents. Thus, these pigs may aid in vaccine development for infectious agents such as the pandemic porcine reproductive and respiratory syndrome virus (PRRSV) and H1N1 swine flu. These pigs are also a first significant step towards generating a pig that expresses fully human, antigen-specific polyclonal Ab to target numerous incurable infectious diseases with high unmet clinical need.

Reproductive biotechniques in buffaloes (Bubalus bubalis): status, prospects and challenges

The swamp buffalo holds tremendous potential in the livestock sector in Asian and Mediterranean countries. Current needs are the faster multiplication of superior genotypes and the conservation of endangered buffalo breeds. Recent advances in assisted reproductive technologies, including in vitro embryo production methodologies, offer enormous opportunities to not only improve productivity, but also to use buffaloes to produce novel products for applications to human health and nutrition. The use of molecular genomics will undoubtedly advance these technologies for their large-scale application and resolve the key problems currently associated with advanced reproductive techniques, such as animal cloning, stem cell technology and transgenesis. Preliminary success in the application of modern reproductive technologies warrants further research at the cellular and molecular levels before their commercial exploitation in buffalo breeding programmes.

Reproduction in the Water Buffalo

In this paper, an account of various aspects related to buffalo reproduction are given. Fundamental concepts of the reproductive physiology as well as manipulation of the reproductive function will be presented. This will include an overview of the most recent developments of the oestrous cycle and the ovulation control, new strategies of reproductive management for the improvement of genetic gain and the application of newly developed reproductive technologies, such as in vitro embryo production, embryo and sperm sexing and cloning.

Cloning cattle: the methods in the madness

Somatic cell nuclear transfer (SCNT) is much more widely and efficiently practiced in cattle than in any other species, making this arguably the most important mammal cloned to date. While the initial objective behind cattle cloning was commercially driven--in particular to multiply genetically superior animals with desired phenotypic traits and to produce genetically modified animals-researchers have now started to use bovine SCNT as a tool to address diverse questions in developmental and cell biology. In this paper, we review current cattle cloning methodologies and their potential technical or biological pitfalls at any step of the procedure. In doing so, we focus on one methodological parameter, namely donor cell selection. We emphasize the impact of epigenetic and genetic differences between embryonic, germ, and somatic donor cell types on cloning efficiency. Lastly, we discuss adult phenotypes and fitness of cloned cattle and their offspring and illustrate some of the more imminent commercial cattle cloning applications.

Biotechnologies and their potential impact on animal breeding and production: a review

Recent developments in mammalian biotechnologies that have been driven largely by medical bioscience, offer new opportunities for livestock industries. Major impacts may be expected in the area of reproductive, genomic and cell technologies that could lead to improved animal breeding strategies or animal production and health applications. In particular, the use of advanced reproductive technologies to select animals at very early stages of life, possibly as early as a 4-day embryo, combined with genomic technologies to predict genetic merit, could lead to significantly increased rates of genetic gain. Such advanced animal breeding technologies will depend strongly on conventional quantitative genetic evaluation systems. Genetic modification in the near future will offer targeted animal improvement options for control of health and production. Long-term impact of genetic modification on animal production systems will depend on consumer acceptance, and its perception by social, environmental and animal welfare groups. However, the opportunity to develop animal products beyond conventional boundaries may prove too attractive with genetic modification eventually being accepted as the norm. The naturally synergistic effect of ex vivo transgenic modification of embryo stem cell or somatic cell lines, combined with nuclear transfer present potentially high value propositions for development of novel and high value products. Opportunities for the mass production of elite males for use in extensive animal production systems will be possible.