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The genomic environment around the Aromatase gene: evolutionary insights.

ABSTRACT: BACKGROUND: The cytochrome P450 aromatase (CYP19), catalyses the aromatisation of androgens to estrogens, a key mechanism in vertebrate reproductive physiology. A current evolutionary hypothesis suggests that CYP19 gene arose at the origin of vertebrates, given that it has not been found outside this clade. The human CYP19 gene is located in one of the proposed MHC-paralogon regions (HSA15q). At present it is unclear whether this genomic location is ancestral (which would suggest an invertebrate origin for CYP19) or derived (genomic location with no evolutionary meaning). The distinction between these possibilities should help to clarify the timing of the CYP19 emergence and which taxa should be investigated. RESULTS: Here we determine the "genomic environment" around CYP19 in three vertebrate species Homo sapiens, Tetraodon nigroviridis and Xenopus tropicalis. Paralogy studies and phylogenetic analysis of six gene families suggests that the CYP19 gene region was structured through "en bloc" genomic duplication (as part of the MHC-paralogon formation). Four gene families have specifically duplicated in the vertebrate lineage. Moreover, the mapping location of the different paralogues is consistent with a model of "en bloc" duplication. Furthermore, we also determine that this region has retained the same gene content since the divergence of Actinopterygii and Tetrapods. A single inversion in gene order has taken place, probably in the mammalian lineage. Finally, we describe the first invertebrate CYP19 sequence, from Branchiostoma floridae. CONCLUSION: Contrary to previous suggestions, our data indicates an invertebrate origin for the aromatase gene, given the striking conservation pattern in both gene order and gene content, and the presence of aromatase in amphioxus. We propose that CYP19 duplicated in the vertebrate lineage to yield four paralogues, followed by the subsequent loss of all but one gene in vertebrate evolution. Finally, we suggest that agnathans and lophotrocozoan protostomes should be investigated for the presence of aromatase.

SUBMITTER: Castro LF

PROVIDER: S-EPMC1215479 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature

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The genomic environment around the Aromatase gene: evolutionary insights.

Castro L Filipe C LF Santos Miguel M MM Reis-Henriques Maria A MA

BMC evolutionary biology 20050812

<h4>Background</h4>The cytochrome P450 aromatase (CYP19), catalyses the aromatisation of androgens to estrogens, a key mechanism in vertebrate reproductive physiology. A current evolutionary hypothesis suggests that CYP19 gene arose at the origin of vertebrates, given that it has not been found outside this clade. The human CYP19 gene is located in one of the proposed MHC-paralogon regions (HSA15q). At present it is unclear whether this genomic location is ancestral (which would suggest an inver ...[more]

PMID: 16098224

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Project description:Background Coral reefs belong to the most ecologically and economically important ecosystems on our planet. Yet, they are under steady decline worldwide due to rising sea surface temperatures, disease, and pollution. Understanding the molecular impact of these stressors on different coral species is imperative in order to predict how coral populations will respond to this continued disturbance. The use of molecular tools such as microarrays has provided deep insight into the molecular stress response of corals. Here, we have performed comparative genomic hybridizations (CGH) with different coral species to an Acropora palmata microarray platform containing 13,546 cDNA clones in order to identify potentially rapidly evolving genes and to determine the suitability of existing microarray platforms for use in gene expression studies (via heterologous hybridization). Results Our results showed that the current microarray platform for A. palmata is able to provide biological relevant information for a wide variety of coral species covering both the complex clade as well the robust clade. Analysis of the fraction of highly diverged genes showed a significantly higher amount of genes without annotation corroborating previous findings that point towards a higher rate of divergence for taxonomically restricted genes. Among the genes with annotation, we found many mitochondrial genes to be highly diverged in M. faveolata when compared to A. palmata, while the majority of nuclear encoded genes maintained an average divergence rate. Conclusions The use of present microarray platforms for transcriptional analyses in different coral species will greatly enhance the understanding of the molecular basis of stress and health and highlight evolutionary differences between scleractinian coral species. On a genomic basis, we show that cDNA arrays can be used to identify patterns of divergence. Mitochondrion-encoded genes seem to have diverged faster than nuclear encoded genes in robust corals. Accordingly, this needs to be taken into account when using mitochondrial markers for scleractinian phylogenies. Microarray experiments were performed as follows. Appropriate Cy3 and Cy5 labeled DNAs were mixed together in a hybridization buffer containing 0.25% SDS, 25 mM HEPES and 3 × SSC, resulting in a final volume of 70?l. The hybridization mixtures were boiled for 2 min at 99°C and allowed to cool at room temperature for 5 min. The cooled hybridization mixtures were pipetted under an mSeries Lifterslip (Erie Scientific), and hybridization took place in Corning hybridization chambers overnight at 55°C. Microarrays were washed once in 2 × SSC, 0.03% SDS heated to 55 °C for 5 min. followed by one wash in 1 x SSC and another wash in 0.2 x SSC for 5 min each. The slides were kept in 0.2 × SSC until analysis. Slides were dried via centrifugation and scanned using an Axon 4000B scanner. The experimental setup followed a reference design, i.e., all samples were hybridized against the same pool of labeled A. palmata DNA. For each species, a total of four hybridizations were performed, including two dye swap hybridizations in order to account for potential dye bias i.e. two hybridizations with Cy3 labeled M. faveolata DNA against a Cy5 labeled A. palmata reference and two hybridizations with Cy5 labeled M. faveolata DNA against a Cy3 labeled Cy3 A. palmata reference were performed. The same hybridization scheme was used for A. cervicornis and S. radians.

Project description:BACKGROUND: Coral reefs belong to the most ecologically and economically important ecosystems on our planet. Yet, they are under steady decline worldwide due to rising sea surface temperatures, disease, and pollution. Understanding the molecular impact of these stressors on different coral species is imperative in order to predict how coral populations will respond to this continued disturbance. The use of molecular tools such as microarrays has provided deep insight into the molecular stress response of corals. Here, we have performed comparative genomic hybridizations (CGH) with different coral species to an Acropora palmata microarray platform containing 13,546 cDNA clones in order to identify potentially rapidly evolving genes and to determine the suitability of existing microarray platforms for use in gene expression studies (via heterologous hybridization). RESULTS: Our results showed that the current microarray platform for A. palmata is able to provide biological relevant information for a wide variety of coral species covering both the complex clade as well the robust clade. Analysis of the fraction of highly diverged genes showed a significantly higher amount of genes without annotation corroborating previous findings that point towards a higher rate of divergence for taxonomically restricted genes. Among the genes with annotation, we found many mitochondrial genes to be highly diverged in M. faveolata when compared to A. palmata, while the majority of nuclear encoded genes maintained an average divergence rate. CONCLUSIONS: The use of present microarray platforms for transcriptional analyses in different coral species will greatly enhance the understanding of the molecular basis of stress and health and highlight evolutionary differences between scleractinian coral species. On a genomic basis, we show that cDNA arrays can be used to identify patterns of divergence. Mitochondrion-encoded genes seem to have diverged faster than nuclear encoded genes in robust corals. Accordingly, this needs to be taken into account when using mitochondrial markers for scleractinian phylogenies.

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Dataset Information

The genomic environment around the Aromatase gene: evolutionary insights.

Publications

The genomic environment around the Aromatase gene: evolutionary insights.

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