Generation and Analysis of Insulin-like growth factor-1 Transgenic Animals

• Main Authors: Cheng-Hung Hsieh, 謝政宏
• Other Authors: Hung-Yi Su
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/82463159339620590289

碩士 === 國立屏東科技大學 === 生物科技研究所 === 94 === The somatomedin hypothesis proposes that the insulin-like growth factors, IGF-1 and IGF-2, mediate action of the growth hormone (GH, somatotropin). Circulating IGF-1 is mainly synthesized and secreted by the liver but it is also produced locally in tissues. The hepatic-derived and local tissues produced IGF-1, mediates the endocrine and autocrine/paracrine action of GH, respectively (Daughaday, 1989). Existing data suggest that locally produced IGF-1 is more important to the development of mammary gland and secretion of milk compared to the systemic IGF-1. As IGF-1 mediates action of GH, it can be used for the treatment of insufficient growth, but also normalise the growth excess, which is excluded by GH treatment. As the chemical structure of IGF-1 is similar to the insulin, it can be used in the diabetic patients. In this study, we set out to produce IGF-1 transgenic mice and goats in which overexpression of ectopic IGF-1 may result in an increased proliferation of mammary gland cells and elevated milk yield. Previous results from our laboratory have suggested that IGF-1 transgenic mice had a significantly (p<0.05) increase in milk yield compared to their non-transgenic littermates. However, these data were derived from mice in the same litter in which the analysis of milk yield was performed in only 3 transgenic and 3 non-transgenic females. In this thesis, we intended to produce more transgenic mice in order to confirm the data of our previous studies. Transgenic goats were also produced using the same transgenic DNA construct as that used in the mice. Nannies of mixed ages were served as embryo donors and recipients. Day 0 was set as the time when both donors and recipients were received the controlled internal drug release (CIDR) for superovulation and estrus synchronization. Both groups of animals were intramuscularly injected with different dosages of hormones including progesterone (PG), pregnant mare's serum gonadotropin (PMSG), human chorionic gonadotropin (HCG), follicle stimulating hormone (FSH) and luteinizing hormone (LH) during different periods of time in the experiment. Naturally mating was performed in approximately 24 hours after CIDR removed from the donors and recipients on day 8. On day 13, microinjection of -lactalbumin-IGF-1 (α-LA-IGF-1) transgenic DNA construct was undertaken in the pronucleus of donor’s embryos. Approximately 2 to 3 injected embryos were transferred to each side of the recipient’s oviducts for the production of transgenic founder animals. Our data showed that 1 of 19 recipients was pregnant as a result of transferring 51 embryos. However, this kid was absent of transgenic DNA, based on the results of polymerase chain reaction (PCR) to screen the genomic DNA extracted from the goat ear. As we are continuing to generate more IGF-1 transgenic goats, further analysis in milk production will be evaluated.