Most studies of erythropoiesis have been performed either with the virally transformed MEL cells or with the scarce erythroblasts within unhomogeneous cell populations.MEL cells are the Friend virus transformed mouse erythroleukemia cells and have lost the capacity to respond to erythropoietin.Moreover,the research in the field of erythropoiesis has been severely hampered by the paucity of erythroblasts obtained from chick embryos,human,mouse,rat fetal liver,mouse spleen,or the bone marrow.In our paper,the fetal blood from newly slaughtered pregnant sheep meets the needs of studies as abundant staring biological materials at the nucleotide level and also reflects in vivo proliferative and differential status of erythroblasts.Appling the technique of mRNA differential display with minor modification,we directly compared cDNA fragmerts from the fetal blood erythroblasts and adult pregnant sheep leukocytes by PCR on DNA sequencing gels and revealed two differentially expressing bands.One is a novel gene fragment, which has homology with UV-sensitive cone opsin or rhodopsin by examinating the predicted amino acid sequence.Since the blood cells are sensitive to radiation,it can be safely inferred that this fragment participate in the process of cytocidal effect of the radiation.The other fragment is glucose induced gene /elongation factor 2 3′end noncoding region,which was first cloned from glucose induced bovine aortic smooth muscle cells.Using Northern blot hybridization method,authentic specific expression was confirmed.
The goat estrus\|associated oviductual glycoprotein(gEGP), which is an important secretary protein in oviduct, is directly associated with the zona pellucida of the ovulated oocyte and with the preimplantation embryo development. To elucidate the physiological function and fundamental mechanism,a goat genomic library, in which plague titer is 1\^15×10\+6 pfu/ml, was constructed. Then, with a probe derived from bovine EGP cDNA, the genomic library was screened and a 18 kb fragment containing the gEGP gene was obtained. After PCR with the primers based on the ovine EGP cDNA, two fragments of gEGP gene were obtained and then sequenced. The predicted exon sequence of gEGP gene shows 99 6%, 96 3%, 89 2%, 88 4%, 88 0%, 87 4%, 84 3%, 74 8% homology with the EGP cDNA of sheep, cow, pig, baboon, rhesus, human, hamster, mouse, respectively. Like the other members of EGP gene family, gEGP gene also has many properties of the chitinase super family, and demonstrates the phylogenetic and functional relativity of EGP family with chitinase family.
