摘要:

SummaryHyaluronan is a major component of synovial tissue and fluid as well as other soft connective tissues. It is a high‐Mrpolysaccharide which forms entangled networks already at dilute concentrations (<1 mg/mL) and endows its solutions with unique rheological properties. Physiological functions of hyaluronan (lubrication, water homeostasis. macromolecular filtering, exclusion, etc.) have been ascribed to the properties of these networks. Recently a number of specific interactions between hyaluronan and a group of proteins named hyaladherins have also pointed towards a role of hyaluronan in recognition and the regulation of cellular activities. Many more or less well documented hypotheses have been proposed for the function of hyaluronan in joints, for example, that it should lubricate, protect cartilage surfaces, scavenge free radicals and debris, keep the joint cavities open, form flow barriers in the synovium and prevent capillary growth.

ISSN:0004-945X    

DOI:10.1038/icb.1996.32

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.33

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.34

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.35

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.36

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.37

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.38

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.39

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1996.40

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryMultiple ovulation and embryo transfer (MOET) now enables researchers to produce identical twin animals, to obtain progeny from pre‐pubertal females and to obtain more offspring from valuable animals. MOET and sexed semen have produced genetic progress of up to 60% of milk production. The oestrous cycles of animals are synchronized with progestagens before superovulation with gonadal hormones, pregnant mare serum gonadotrophin and follicle stimulating hormone. Surgical, non‐surgical and laparoscopic methods are applied to recover and transfer embryos. Sexing and genotyping of the pre‐implantation embryos is a key step in improving the management and breeding programmes for livestock, as well as in the human for the prenatal diagnosis of genetic disorders. Several serological and physiological methods have been used to determine the sex of the pre‐implantation embryos; none has had satisfactory results in terms of time and accuracy, Sexing by polymerase chain reaction (PCR) using male‐specific chromosome sequences alone or with female‐specific chromosomal DNA probes simultaneously has been sufficient to identify the sex of the embryos with 100% accuracy. However, caution should be taken against sources of the contamination. The MHC class I, class II and background genes have been implicated in resistance to internal parasites in animals, Biotechnological methods such as screening of embryos prior to transfer using PCR and primer extension pre‐amplification have already made it possible to detect transgenic or genetically disordered embryos and could be applied to select those embryos bearing immunological genotypes of interest, such as resistance to internal parasites. Ultimately, cloning and nuclear transplantation would provide the possibility of isolating these resistance genes and to transfer them to livestock pre‐implantation embryos to propagate these desirable traits.

ISSN:0004-945X    

DOI:10.1038/icb.1996.16

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY