Sex steroidal hormones induce differential gene expressions in Mozambique tilapia fry (Oreochromis mossambicus)
Date Issued
2004
Date
2004
Author(s)
Ju, Chi-Ching
DOI
zh-TW
Abstract
The development and growth of sex organs is mainly mediated by sex hormones, including estrogen and testosterone, which govern the female and male development, respectively. Exogenous sex steroids have a remarkable influence on phenotypic sex. It is well demonstrated that the exogenous steroids affect sex differentiation in developing fry（Baroiller et al., 1999）. However, the changes in gene expression upon sex hormone treatments in fry are less clear. To approach this question, we examine the changes in gene expression pattern in fry of tilapia, Oreochromis mossambicus, under the influences of exogenous steroids, 17?methyltestosterone (MT) and 17β- estradiol（E2）. Mozambique tilapia is an excellent model for studying steroidogenic actions during gonadal sex differentiation since the sex can be altered by sex hormones irregardless of its genetic sex. Therefore, we had adapted a method from Tsai et al. (2000) to prepare all male or all female tilapia. We then performed PCR subtracted hybridization on those homo-sex fry and identified some sex steroid-induced differentially expressed genes in developing tilapia fry. Among those genes, we found parvalbumin and transferrin were up-regulated by MT during sex-sensitive periods in tilapia. We have cloned the full open reading frame of parvalbumin. Parvalbumin expressed in brain, muscle and skin as tissue-specific isoforms, respectively. From their amino acid sequences, we suggest that one or two amino acid shift could decrease the sequence similarity of calcium-binding motif. We have also cloned a transferrin with partial sequence. Transferrin expressed in liver, heart, eye and brain. We also have cloned a longer transferrin fragment（753 bp）in the ovary. The up-regulation of parvalbumin by MT were confirmed by quantitative-PCR. Using in-situ hybridization, we found that parvalbumin was expressed in the hippocampus and sarcoplasmic reticulum, and transferrin was expressed in the brain choroids plexus. The significance of up-regulation of parvalbumin and transferrin by MT is still under investigation.
Subjects
性別分化
性類固醇激素
仔魚
Sex steroidal hormones
sex differentiation
fry
Type
other
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