Dataset Information

Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems.

ABSTRACT: Fish use olfaction to sense a variety of nonvolatile chemical signals in water. However, the evolutionary importance of olfaction in species-rich cichlids is controversial. Here, we determined an almost complete sequence of the vomeronasal type 2 receptor-like (OlfC: putative amino acids receptor in teleosts) gene cluster using the bacterial artificial chromosome library of the Lake Victoria cichlid, Haplochromis chilotes. In the cluster region, we found 61 intact OlfC genes, which is the largest number of OlfC genes identified among the seven teleost fish investigated to date. Data mining of the Oreochromis niloticus (Nile tilapia) draft genome sequence, and genomic Southern hybridization analysis revealed that the ancestor of all modern cichlids had already developed almost the same OlfC gene repertoire, which was accomplished by lineage-specific gene expansions. Furthermore, comparison of receptor sequences showed that recently duplicated paralogs are more variable than orthologs of different species at particular sites that were predicted to be involved in amino acid selectivity. Thus, the increase of paralogs through gene expansion may lead to functional diversification in detection of amino acids. This study implies that cichlids have developed a potent capacity to detect a variety of amino acids (and their derivatives) through OlfCs, which may have contributed to the extraordinary diversity of their feeding habitats.

SUBMITTER: Nikaido M

PROVIDER: S-EPMC3641633 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems.

Nikaido Masato M Suzuki Hikoyu H Toyoda Atsushi A Fujiyama Asao A Hagino-Yamagishi Kimiko K Kocher Thomas D TD Carleton Karen K Okada Norihiro N

Genome biology and evolution 20130101 4

Fish use olfaction to sense a variety of nonvolatile chemical signals in water. However, the evolutionary importance of olfaction in species-rich cichlids is controversial. Here, we determined an almost complete sequence of the vomeronasal type 2 receptor-like (OlfC: putative amino acids receptor in teleosts) gene cluster using the bacterial artificial chromosome library of the Lake Victoria cichlid, Haplochromis chilotes. In the cluster region, we found 61 intact OlfC genes, which is the larges ...[more]

PMID: 23501830

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Project description:In Darwinian evolution, mutations occur approximately at random in a gene, turned into amino acid mutations by the genetic code. Some mutations are fixed to become substitutions and some are eliminated from the population. Partitioning pairs of closely related species with complete genome sequences by average population size of each pair, we looked at the substitution matrices generated for these partitions and compared the substitution patterns between species. We estimated a population genetic model that relates the relative fixation probabilities of different types of mutations to the selective pressure and population size. Parameterizations of the average and distribution of selective pressures for different amino acid substitution types in different population size comparisons were generated with a Bayesian framework. We found that partitions in population size as well as in substitution type are required to explain the substitution data. Selection coefficients were found to decrease with increasingly radical amino acid substitution and with increasing effective population size. To further explore the role of underlying processes in amino acid substitution, we analyzed embryophyte (plant) gene families from TAED (The Adaptive Evolution Database), where solved structures for at least one member exist in the Protein Data Bank. Using PAML, we assigned branches to three categories: strong negative selection, moderate negative selection/neutrality, and positive diversifying selection. Focusing on the first and third categories, we identified sites changing along gene family lineages and observed the spatial patterns of substitution. Selective sweeps were expected to create primary sequence clustering under positive diversifying selection. Co-evolution through direct physical interaction was expected to cause tertiary structural clustering. Under both positive and negative selection, the substitution patterns were found to be nonrandom. Under positive diversifying selection, significant independent signals were found for primary and tertiary sequence clustering, suggesting roles for both selective sweeps and direct physical interaction. Under strong negative selection, the signals were not found to be independent. All together, a complex interplay of population genetic and protein thermodynamics forces is suggested.

Dataset Information

Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems.

Publications

Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems.

Similar Datasets

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