Propagation Techniques of Ewes at Early Age

The integration of hormone induction of young ewes,live oocyte collection,in-vitro fertilization and embryo transfer( JIVET),as a major breakthrough in livestock breeding technology,not only solves the problem of low oocytes obtained from adult ewes by hormone induction in production practice,but also significantly improves production efficiency. This technology can reduce the generation interval of cattle and sheep and speed up the acquisition of genes in genetic breeding. The application of this technology can help accelerate the cultivation process,shorten the generation interval,promote the industrialization and improve the economic benefits of beef cattle breed. This paper provides a reference for the research and application of new breeding and propagation techniques of beef cattle.

High-efficiency Embryo Cryopreservation Technology for Mutton Sheep

Embryo cryopreservation is an important part of embryo biotechnology.It plays a key role in the development of quality animal husbandry.However,the effect of in-vivo(in-vitro)embryo freezing of cattle and sheep in China has not reached an expected level,which limits the commercial application of embryo transfer technology.The technical bottleneck that needs to be broken through is that embryos are subject to mechanical damage and protective agent toxicity during freezing and thawing.This paper summarized the successful application of plant antifreeze protein in vitrification preservation of pig embryos,which makes this technology widely used in animal husbandry production,and is of great significance in accelerating the large-scale breeding of improved livestock and saving endangered animals.

Technical Measures for Rapid Propagation of Improved Beef Cattle

Based on early weaning in calves,hormone induction in young calves,intravital egg collection,in-vitro fertilization and embryo transfer which serve as major breakthroughs in livestock breeding technology,the techniques of hormone induction and in-vitro fertilization were integrated,not only to solve the problem of obtaining oocytes by hormone induction in adult cows in production practice,but also to obviously improve production efficiency.The application of this technology can help accelerate the cultivation process,shorten the generation interval,promote the industrialization and improve the economic benefits of beef cattle breed.This paper provides a reference for the research and application of new breeding and propagation techniques of beef cattle.

Establishment and application of both FLP and Cre site-specific recombination systems at the same position in the genome

Both FRT-FRT and LoxP-LoxP sites that are the target sepuences of site-specific recombinases have been constructed in a vector, called C4LFY, using the recombinant DNA technigue. C4LFY also contains P elements, 2 exons and 1 intron of Drosophila yellow gene, yellow promoter and enhancers, and flanking DNA. Since C4LFY made use of two pairs of FRT and LoxP sites, this vector included two site-specific recombination systems. C4LFY was then integrated into Drosophila genome by P-element-mediated germ line transformation. in the presence of the FLP or Cre recombinase, either FLP/FRT or Cre/LoxP recombination reaction was successfully created at the same position in the genome. Using this system, the molecular basis of yellow gene expression and regulation during development have been investigated. Results indicate that the tissue-specific expression of yellow gene is directly regulated by transcriptional enhancers. in addition, the 5’ and 3’ genomic sequences flanking the yellow gene have been