The insulin-like growth factor I (IGF-I) gene is expressed in chick embryos during early organogenesis.
A definition of the role of IGF-I in differentiation and development requires a detailed understanding of its expression and tissue-specific regulation in embryogenesis. Standard techniques for analysis of IGF-I gene expression are not sufficiently sensitive for studies in early embryos. We have used the highly sensitive polymerase chain reaction (PCR) to study IGF-I gene expression in whole chick embryos from the late blastula stage (E0 = laying) through the end of organogenesis (day 8), and in liver, brain and pancreas during mid-late embryogenesis and perinatally (hatching = day 21). Although at low levels in the blastoderm and gastrula, IGF-I mRNA was detectable in the whole embryo in all stages studied, with a tendency of the signal to increase with age during the first week of embryogenesis. In mid- and late embryogenesis, we easily detected IGF-I mRNA transcripts in pancreas and brain while the levels in the liver were barely detectable. Liver IGF-I mRNA increased markedly at the peak of postnatal growth (day 50). These studies suggest that while the major source of postnatal IGF-I may be the liver, extrahepatic tissues may be the predominant source of IGF-I during prenatal chicken development.
Serrano
J
J
Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892.
Shuldiner
A R
AR
Roberts
C T
CT
LeRoith
D
D
de Pablo
F
F
D000818:Animals; D001483:Base Sequence; D001756:Blastoderm / Q000378:metabolism; D001921:Brain / Q000196:embryology / Q000378:metabolism; D002642:Chick Embryo / Q000378:metabolism*; D003001:Cloning, Molecular; D005775:Gastrula / Q000378:metabolism; D015870:Gene Expression; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008099:Liver / Q000196:embryology / Q000378:metabolism; D008969:Molecular Sequence Data; D010179:Pancreas / Q000196:embryology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D013002:Somatomedins / Q000235:genetics*
D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I