Comparison of a vitellogenin gene between two distantly related rhabditid nematode species.
Three vitellogenin genes from the free-living nematode Caenorhabditis elegans have previously been characterized at the molecular level. In order to study evolutionary relationships within this poorly understood taxon, we have cloned a vitellogenin gene, CEW1-vit-6, from a distantly related species belonging to the same family as C. elegans. Screening of a genomic library with a probe to total poly(A+) RNA yielded three clones that hybridized more intensely than all others, and all three corresponded to a single gene homologous to C. elegans vit-6. Comparison of CEW1-vit-6 with Ce-vit-6 reveals both strong similarities and surprising differences. Life Ce-vit-6, the gene is about 5 kb long and contains four unusually small introns (38-41 nt), but only one interrupts the gene at the same location as a Ce-vit-6 intron. The promoter region contains five matches to Vitellogenin Promoter Element 1 (VPE1) and no matches to VPE2, both previously shown to be required for vit gene transcription in C. elegans. Codon usage is in general similar to that of the Ce-vit genes, but a few codon biases are quite different. Alignment of the CEW1-vit-6 protein with Ce-vit-6 and Ce-vit-2 products suggests the existence of two domains which have evolved at different rates. Sequence comparison shows that nematode vitellogenins are much more closely related to vertebrate than to insect vitellogenins.
Winter
C E
CE
Departamento de Parasitologia, Instituto de Ciências Biomédicas-USP, Brazil. cewinter@biomed.icb2.usp.br
Penha
C
C
Blumenthal
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics; D018509:DNA, Helminth / Q000235:genetics; D017238:Genes, Helminth / Q000235:genetics*; D015698:Genomic Library; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D017168:Rhabditida / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014819:Vitellogenins / Q000235:genetics*
D003062:Codon; D018509:DNA, Helminth; D014819:Vitellogenins