MBE Advance Access originally published online on October 19, 2006
Molecular Biology and Evolution 2007 24(1):253-268; doi:10.1093/molbev/msl152
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Research Articles |
Molecular Characterization of Crustacean Visual Pigments and the Evolution of Pancrustacean Opsins
* Department of Microbiology and Molecular Biology, Brigham Young University
Department of Biological Sciences, University of Maryland Baltimore County
Department of Integrative Biology, Brigham Young University
E-mail: porter{at}umbc.edu.
Accepted for publication October 11, 2006.
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 
-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 Å of the chromophore and thus have the potential to affect spectral tuning.
Key Words: TreeSAAP • selection • opsin evolution • Crustacea • visual pigment absorbance
Adriana Briscoe, Associate Editor
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  V. K. Iyengar and B. D. Starks Sexual selection in harems: male competition plays a larger role than female choice in an amphipod Behav. Ecol., February 24, 2008; (2008) arn009v1. [Abstract] [Full Text] [PDF]
|
|