Two forms of Xenopus nuclear factor 7 have overlapping spatial but different temporal patterns of expression during development.
Xenopus nuclear factor 7 (xnf7) is a maternal gene product that functions in the determination of the dorsal-ventral body axis. We have cloned two xnf7 cDNAs, xnf7-O and xnf7-B, that have a different temporal pattern of expression. The cDNAs differ by 39 amino acid residues scattered throughout the molecule. Most of the changes were conservative in nature. Using gene specific probes we found that xnf7-O transcripts were abundant in oocytes and decreased until the neurula stage, after which they increased in abundance. Xnf7-B transcripts were in low abundance in oocytes and were expressed at high levels at the neurula stage and in adult brain. Both xnf7-O and xnf7-B transcripts at the neurula stage were localized in the dorsal region of the embryo, including the neural folds and somites. Xnf7 was not expressed in ventralized embryos that lacked dorsal structures, thereby substantiating its dorsal localization in the embryo. The promoter region of the xnf7-O gene does not possess a TATA box but does contain E2F, USF, Sp1-like and AP1 binding sites within the first 421 bp from the transcription initiation site. A 62 bp fragment of the xnf7-O promoter containing the Sp1-like and E2F sites can direct proper spatial expression of a transgene in embryos.
Gong
S G
SG
Department of Molecular Genetics, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
Reddy
B A
BA
Etkin
L D
LD
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D004527:Egg Proteins / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D015698:Genomic Library; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D009865:Oocytes / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D013997:Time Factors; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D004527:Egg Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D029867:Xenopus Proteins; C071551:XNF7 protein, Xenopus