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Transcriptomic analyses reveal novel genes with sexually dimorphic expression in the zebrafish gonad and brain.

Sreenivasan R, Cai M, Bartfai R, Wang X, Christoffels A, Orban L - PLoS ONE (2008)

Bottom Line: We found that five members of the GTP-binding septin gene family, from which only one member (septin 4) has previously been implicated in reproduction in mice, were all strongly expressed in the gonads.Our microarray would be useful for studying gonad development, differentiation and function not only in zebrafish but also in related teleosts via cross-species hybridizations.Since several genes have been shown to play similar roles in gonadogenesis in zebrafish and other vertebrates, our array may even provide information on genetic disorders affecting gonadal phenotypes and fertility in mammals.

View Article: PubMed Central - PubMed

Affiliation: Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore, Singapore.

ABSTRACT

Background: Our knowledge on zebrafish reproduction is very limited. We generated a gonad-derived cDNA microarray from zebrafish and used it to analyze large-scale gene expression profiles in adult gonads and other organs.

Methodology/principal findings: We have identified 116638 gonad-derived zebrafish expressed sequence tags (ESTs), 21% of which were isolated in our lab. Following in silico normalization, we constructed a gonad-derived microarray comprising 6370 unique, full-length cDNAs from differentiating and adult gonads. Labeled targets from adult gonad, brain, kidney and 'rest-of-body' from both sexes were hybridized onto the microarray. Our analyses revealed 1366, 881 and 656 differentially expressed transcripts (34.7% novel) that showed highest expression in ovary, testis and both gonads respectively. Hierarchical clustering showed correlation of the two gonadal transcriptomes and their similarities to those of the brains. In addition, we have identified 276 genes showing sexually dimorphic expression both between the brains and between the gonads. By in situ hybridization, we showed that the gonadal transcripts with the strongest array signal intensities were germline-expressed. We found that five members of the GTP-binding septin gene family, from which only one member (septin 4) has previously been implicated in reproduction in mice, were all strongly expressed in the gonads.

Conclusions/significance: We have generated a gonad-derived zebrafish cDNA microarray and demonstrated its usefulness in identifying genes with sexually dimorphic co-expression in both the gonads and the brains. We have also provided the first evidence of large-scale differential gene expression between female and male brains of a teleost. Our microarray would be useful for studying gonad development, differentiation and function not only in zebrafish but also in related teleosts via cross-species hybridizations. Since several genes have been shown to play similar roles in gonadogenesis in zebrafish and other vertebrates, our array may even provide information on genetic disorders affecting gonadal phenotypes and fertility in mammals.

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In situ hybridization revealed expression in the germline for ovary- and testis-enhanced genes.Adult ovary (A–E) and adult testis (F–J) sections were hybridized with DIG-labeled riboprobes of ten genes which expressed strongly in either one of the gonads. Images are arranged from top to bottom in order of decreasing in situ hybridization signal intensity. Microarray expression levels for each gene across the eight organs analyzed are indicated by the coloured expression profiles. (A: zp2, B: btg4, C: CO350808, D: gez1, E: CO350303, F: gez2, G: sept4, H: CO353006, I: tekt1, J: MGC75611; I, II, III: stage I, II and III oocytes; psc: primary spermatocytes, ssc: secondary spermatocytes; FB, FO, FK and FRB represent the brain, ovary, kidney and ‘rest-of-body’ from female zebrafish, while MB, MT, MK and MRB represent the brain, testis, kidney and ‘rest-of-body’ from male zebrafish.)
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pone-0001791-g002: In situ hybridization revealed expression in the germline for ovary- and testis-enhanced genes.Adult ovary (A–E) and adult testis (F–J) sections were hybridized with DIG-labeled riboprobes of ten genes which expressed strongly in either one of the gonads. Images are arranged from top to bottom in order of decreasing in situ hybridization signal intensity. Microarray expression levels for each gene across the eight organs analyzed are indicated by the coloured expression profiles. (A: zp2, B: btg4, C: CO350808, D: gez1, E: CO350303, F: gez2, G: sept4, H: CO353006, I: tekt1, J: MGC75611; I, II, III: stage I, II and III oocytes; psc: primary spermatocytes, ssc: secondary spermatocytes; FB, FO, FK and FRB represent the brain, ovary, kidney and ‘rest-of-body’ from female zebrafish, while MB, MT, MK and MRB represent the brain, testis, kidney and ‘rest-of-body’ from male zebrafish.)

Mentions: ISH results showed the expected expression in the gonad for five of the six ovary-expressed genes and eight of the ten testis-expressed genes analyzed (see Table S7), indicating an 81.3% concurrence with our array data. Images of ISH signals in gonad sections for five ovary- and five testis-expressed genes, together with their expression profiles from the microarray, are shown in Fig. 2. Nine of the ten genes shown had a positive correlation of ISH signal intensities with their corresponding gene expression levels as reflected from our array data (Fig. 2; Table S7), hence reinforcing the validity of our hybridization results. Four genes with unknown functions that showed ovary- or testis-enhanced expression were defined in our study as gez1-gez4 (‘gez’: gonad-expressed in zebrafish; see Fig. 2D, Fig. 2F and Table S7).


Transcriptomic analyses reveal novel genes with sexually dimorphic expression in the zebrafish gonad and brain.

Sreenivasan R, Cai M, Bartfai R, Wang X, Christoffels A, Orban L - PLoS ONE (2008)

In situ hybridization revealed expression in the germline for ovary- and testis-enhanced genes.Adult ovary (A–E) and adult testis (F–J) sections were hybridized with DIG-labeled riboprobes of ten genes which expressed strongly in either one of the gonads. Images are arranged from top to bottom in order of decreasing in situ hybridization signal intensity. Microarray expression levels for each gene across the eight organs analyzed are indicated by the coloured expression profiles. (A: zp2, B: btg4, C: CO350808, D: gez1, E: CO350303, F: gez2, G: sept4, H: CO353006, I: tekt1, J: MGC75611; I, II, III: stage I, II and III oocytes; psc: primary spermatocytes, ssc: secondary spermatocytes; FB, FO, FK and FRB represent the brain, ovary, kidney and ‘rest-of-body’ from female zebrafish, while MB, MT, MK and MRB represent the brain, testis, kidney and ‘rest-of-body’ from male zebrafish.)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2262149&req=5

pone-0001791-g002: In situ hybridization revealed expression in the germline for ovary- and testis-enhanced genes.Adult ovary (A–E) and adult testis (F–J) sections were hybridized with DIG-labeled riboprobes of ten genes which expressed strongly in either one of the gonads. Images are arranged from top to bottom in order of decreasing in situ hybridization signal intensity. Microarray expression levels for each gene across the eight organs analyzed are indicated by the coloured expression profiles. (A: zp2, B: btg4, C: CO350808, D: gez1, E: CO350303, F: gez2, G: sept4, H: CO353006, I: tekt1, J: MGC75611; I, II, III: stage I, II and III oocytes; psc: primary spermatocytes, ssc: secondary spermatocytes; FB, FO, FK and FRB represent the brain, ovary, kidney and ‘rest-of-body’ from female zebrafish, while MB, MT, MK and MRB represent the brain, testis, kidney and ‘rest-of-body’ from male zebrafish.)
Mentions: ISH results showed the expected expression in the gonad for five of the six ovary-expressed genes and eight of the ten testis-expressed genes analyzed (see Table S7), indicating an 81.3% concurrence with our array data. Images of ISH signals in gonad sections for five ovary- and five testis-expressed genes, together with their expression profiles from the microarray, are shown in Fig. 2. Nine of the ten genes shown had a positive correlation of ISH signal intensities with their corresponding gene expression levels as reflected from our array data (Fig. 2; Table S7), hence reinforcing the validity of our hybridization results. Four genes with unknown functions that showed ovary- or testis-enhanced expression were defined in our study as gez1-gez4 (‘gez’: gonad-expressed in zebrafish; see Fig. 2D, Fig. 2F and Table S7).

Bottom Line: We found that five members of the GTP-binding septin gene family, from which only one member (septin 4) has previously been implicated in reproduction in mice, were all strongly expressed in the gonads.Our microarray would be useful for studying gonad development, differentiation and function not only in zebrafish but also in related teleosts via cross-species hybridizations.Since several genes have been shown to play similar roles in gonadogenesis in zebrafish and other vertebrates, our array may even provide information on genetic disorders affecting gonadal phenotypes and fertility in mammals.

View Article: PubMed Central - PubMed

Affiliation: Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore, Singapore.

ABSTRACT

Background: Our knowledge on zebrafish reproduction is very limited. We generated a gonad-derived cDNA microarray from zebrafish and used it to analyze large-scale gene expression profiles in adult gonads and other organs.

Methodology/principal findings: We have identified 116638 gonad-derived zebrafish expressed sequence tags (ESTs), 21% of which were isolated in our lab. Following in silico normalization, we constructed a gonad-derived microarray comprising 6370 unique, full-length cDNAs from differentiating and adult gonads. Labeled targets from adult gonad, brain, kidney and 'rest-of-body' from both sexes were hybridized onto the microarray. Our analyses revealed 1366, 881 and 656 differentially expressed transcripts (34.7% novel) that showed highest expression in ovary, testis and both gonads respectively. Hierarchical clustering showed correlation of the two gonadal transcriptomes and their similarities to those of the brains. In addition, we have identified 276 genes showing sexually dimorphic expression both between the brains and between the gonads. By in situ hybridization, we showed that the gonadal transcripts with the strongest array signal intensities were germline-expressed. We found that five members of the GTP-binding septin gene family, from which only one member (septin 4) has previously been implicated in reproduction in mice, were all strongly expressed in the gonads.

Conclusions/significance: We have generated a gonad-derived zebrafish cDNA microarray and demonstrated its usefulness in identifying genes with sexually dimorphic co-expression in both the gonads and the brains. We have also provided the first evidence of large-scale differential gene expression between female and male brains of a teleost. Our microarray would be useful for studying gonad development, differentiation and function not only in zebrafish but also in related teleosts via cross-species hybridizations. Since several genes have been shown to play similar roles in gonadogenesis in zebrafish and other vertebrates, our array may even provide information on genetic disorders affecting gonadal phenotypes and fertility in mammals.

Show MeSH
Related in: MedlinePlus