Two Cyp19 (P450 Aromatase) Genes on Duplicated Zebrafish Chromosomes Are Expressed in Ovary or Brain

Abstract

Cytochrome P450 aromatase (Cyp19) is an enzyme catalyzing the synthesis of estrogens, thereby controlling various physiological functions of estrogens. We isolated two cyp19 cDNAs, termed cyp19a and cyp19b, respectively, from zebrafish. These genes are located in linkage groups 18 and 25, respectively. Detailed gene mapping indicated that zebrafish linkage groups 18 and 25 may have arisen from the same ancestral chromosome by a chromosome duplication event. Cyp19a is expressed mainly in the follicular cells lining the vitellogenic oocytes in the ovary during vitellogenesis. Cyp19b is expressed abundantly in the brain, at the hypothalamus and ventral telencephalon, extending to the olfactory bulbs. The expression of duplicated cyp19 genes at two different tissues highlights the evolutionary significance of maintaining two active genes on duplicated zebrafish chromosomes for specific functions in the ovary and the brain.

20β-hydroxysteroid dehydrogenase and CYP19A1 are differentially expressed during maturation in Atlantic cod (Gadus morhua)

“…In mammals, only one cyp19 gene exists, and tissue specificity and developmental expression patterns are generated by differential use of promoters. Teleosts, however, have two cytochrome P450 aromatase genes, probably generated by gene duplication during evolution (Chiang et al 2001). The form primarily expressed in the ovary is designated cyp19a1, while the form predominantly expressed in the brain is termed cyp19a2.…”

Anti‐Müllerian hormone and 11 β‐hydroxylase show reciprocal expression to that of aromatase in the transforming gonad of zebrafish males

“…Similarly to the mammalian orthologs, zebrafish amh is highly expressed in the Sertoli cells after testicular differentiation (Rodriguez-Mari et al, 2005). At the same time, amh transcript could also be detected in the ovarian follicle layer where cyp19a1a is expressed (Chiang et al, 2001;Goto-Kazeto et al, 2004;Rodriguez-Mari et al, 2005), suggesting that they are colocalized in the same cells. However, these studies have not investigated whether amh was involved in the "juvenile ovaryto-testis" transformation.…”

“…Two different cyp19a1 loci have been identified in zebrafish: cyp19a1a is predominantly expressed in the ovary, whereas cyp19a1b mainly in the brain (Chiang et al, 2001). The transcript level of cyp19a1a was found to be 100 times higher in adult ovary than in testis by real-time polymerase chain reaction (PCR); however, there was no obvious difference in the level of cyp19a1b between female and male brains (Sawyer et al, 2006).…”

Aromatase activity in the ovary and brain of the eastern mosquitofish (Gambusia holbrooki) exposed to paper mill effluent.

“…This enzyme has been identified in the gonad, liver, brain, and various peripheral tissues, such as fat cells in mammals, as well as in the gonad and brain of all other vertebrates including fishes and the cephalochordate, amphioxus (27)(28)(29). At least two forms of aromatase have been reported in mammals and fishes, with gonadal and brain forms coded for on two separate genes (30)(31)(32). Aromatase expression is constitutive in some tissues, but aromatase expression and activity can be altered by temperature, season, and various hormones, such as steroids (33)(34)(35).…”