Inferring the Evolution of Teleostean zp Genes Based on Their Sites of Expression
Article first published online: 2 MAY 2013
Copyright © 2013 Wiley Periodicals, Inc.
Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
Volume 320, Issue 5, pages 332–343, July 2013
How to Cite
2013. Inferring the evolution of teleostean zp genes based on their sites of expression. J. Exp. Zool. (Mol. Dev. Evol.) 320B:332–343., , , , , .
- Issue published online: 10 JUN 2013
- Article first published online: 2 MAY 2013
- Manuscript Accepted: 1 APR 2013
- Manuscript Revised: 26 FEB 2013
- Manuscript Received: 3 OCT 2012
- JSPS. Grant Numbers: 21570240, 70612092
Fish egg envelopes consist of several glycoproteins, called zona pellucida (ZP) proteins, which are conserved among chordates. Euteleosts synthesize ZP proteins in the liver, while elopomorphs synthesize them in the ovaries. In Cypriniformes, zp genes are expressed in the ovaries. We investigated the zp genes of two Otocephalan orders: Clupeiformes (Pacific herring and Japanese anchovy) and Gonorynchiformes (milkfish), which diverged earlier than Cypriniformes. cDNA cloning of zp gene homologs revealed that Pacific herring and Japanese anchovy possessed both ovary- and liver-expressed zp genes; however, the zp genes of milkfish were only expressed in the ovaries. Molecular phylogenetic analysis showed that ovary- and liver-expressed zpc genes of two the Clupeiformes formed independent clades. Based on this, we hypothesized the evolution of teleostean zp genes, focusing on the organ expressing zp gene. As in other chordates, the original site of expression of zp genes was likely the ovary. In the early stage of teleostean evolution, the ancestral zp genes acquired the ability to express in the liver. Later, one of the two expression sites became dominant. The liver-expressed zp genes are component proteins of the egg envelope in the Euteleostei. In Otocephala, Clupeiformes possess both ovary- and liver-expressed genes that presumably participate in egg envelope formation, whereas the Gonorynchiformes and Cypriniformes have primarily preserved ovary expressed zp genes. J. Exp. Zool. (Mol. Dev. Evol.) 320B:332–343, 2013. © 2013 Wiley Periodicals, Inc.