Molecular characterization of crustacean visual pigments and the evolution of pancrustacean opsins.

Full Abstract

Investigations of opsin evolution outside of vertebrate systems have long been focused on insect visual pigments, whereas other groups have received little attention. Furthermore, few studies have explicitly investigated the selective influences across all the currently characterized arthropod opsins. In this study, we contribute to the knowledge of crustacean opsins by sequencing 1 opsin gene each from 6 previously uncharacterized crustacean species (Euphausia superba, Homarus gammarus, Archaeomysis grebnitzkii, Holmesimysis costata, Mysis diluviana, and Neomysis americana). Visual pigment spectral absorbances were measured using microspectrophotometry for species not previously characterized (A. grebnitzkii=496 nm, H. costata=512 nm, M. diluviana=501 nm, and N. americana=520 nm). These novel crustacean opsin sequences were included in a phylogenetic analysis with previously characterized arthropod opsin sequences to determine the evolutionary placement relative to the well-established insect spectral clades (long-/middle-/short-wavelength sensitive). Phylogenetic analyses indicate these novel crustacean opsins form a monophyletic clade with previously characterized crayfish opsin sequences and form a sister group to insect middle-/long-wavelength-sensitive opsins. The reconstructed opsin phylogeny and the corresponding spectral data for each sequence were used to investigate selective influences within arthropod, and mainly "pancrustacean," opsin evolution using standard dN/dS ratio methods and more sensitive techniques investigating the amino acid property changes resulting from nonsynonymous replacements in a historical (i.e., phylogenetic) context. Although the conservative dN/dS methods did not detect any selection, 4 amino acid properties (coil tendencies, compressibility, power to be at the middle of an alpha-helix, and refractive index) were found to be influenced by destabilizing positive selection. Ten amino acid sites relating to these properties were found to face the binding pocket, within 4 A of the chromophore and thus have the potential to affect spectral tuning.

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Author information

Author/s: Porter, Megan L (ML); Cronin, Thomas W (TW); McClellan, David A (DA); Crandall, Keith A (KA);

Affiliation: Department of Microbiology and Molecular Biology, Brigham Young University. porter(-atsign-)umbc.edu

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.

Journal: Molecular biology and evolution (Mol Biol Evol), published in United States. (Language: eng)

Reference: 2007-Jan; vol 24 (issue 1) : pp 253-68

Dates: Created 2006/12/18; Completed 2007/04/02; Revised 2008/11/21;

PMID: 17053049, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Crustacea - chemistry; genetics
Evolution, Molecular
Molecular Sequence Data
Phylogeny

Associated Chemicals: Rod Opsins (0)

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