Hirabayashi M, Kodaira K, Takahashi R, Sagara J, Suzuki T, Ueda M
YS New Technology Institute, Inc., Tochigi, Japan.
Mol Reprod Dev. 1996 Feb;43(2):145-9. doi: 10.1002/(SICI)1098-2795(199602)43:2<145::AID-MRD2>3.0.CO;2-R.
Transgene expression in the mammary glands of newborn rats was studied to establish an early selection system for transgenic animals producing exogenous proteins in their milk during lactation. A fusion gene composed of the bovine alpha S1 casein gene promoter and the human growth hormone gene was microinjected into rat embryos. Transgenic lines that produced human growth hormone in their milk were established and used in this study. Immediately after birth, and without any hormone treatment, human growth hormone was found in the extracts of mammary glands from both male and female rats derived from the line secreting human growth hormone in their milk. The expression of the transgene in mammary glands of newborn rats was also detected by the presence of human growth hormone mRNA. Nontransgenic newborn rats did not express the human growth hormone gene in their mammary glands, while the mRNA for rat alpha casein, an endogenous milk protein, was found in all mammary glands from both transgenic and nontransgenic neonates. These results show that analyzing the expression of transgenes in the mammary glands of neonates is a valuable tool to select the desired transgenic animals and to shorten the selection schedules establishing the transgenic animals.
为建立一种早期筛选系统，用于筛选在哺乳期能在乳汁中产生外源蛋白的转基因动物，研究了新生大鼠乳腺中的转基因表达情况。将由牛αS1酪蛋白基因启动子和人生长激素基因组成的融合基因显微注射到大鼠胚胎中。建立了能在乳汁中产生人生长激素的转基因品系并用于本研究。出生后立即在未经任何激素处理的情况下，在源自乳汁中分泌人生长激素品系的雄性和雌性大鼠的乳腺提取物中发现了人生长激素。通过人生长激素mRNA的存在也检测到了新生大鼠乳腺中转基因的表达。非转基因新生大鼠在其乳腺中不表达人生长激素基因，而在转基因和非转基因新生大鼠的所有乳腺中都发现了大鼠α酪蛋白（一种内源性乳蛋白）的mRNA。这些结果表明，分析新生大鼠乳腺中转基因的表达是筛选所需转基因动物以及缩短建立转基因动物的筛选周期的有价值工具。
