Volume 16, Issue 3, Pages R81-R83 (February 2006) Shortwave visual sensitivity in tree and flying squirrels reflects changes in lifestyle  Lívia dos S. Carvalho, Jill A. Cowing, Susan E. Wilkie, James K. Bowmaker, David M. Hunt  Current Biology  Volume 16, Issue 3, Pages R81-R83 (February 2006) DOI: 10.1016/j.cub.2006.01.045 Copyright © 2006 Elsevier Ltd Terms and Conditions

Figure 1 Rodent SWS1 opsins. (A) Cladogram showing evolution of VS pigments (dashed line) in both rodent lineages. Only species with confirmed UVS or VS pigments are included. 1Nocturnal; 2diurnal; 3burrowing/fossorial. (B) Difference spectra for recombinant wild-type and Tyr86Phe mutant grey squirrel SWS1 opsins. The Tyr86Phe mutant pigment was generated by site-directed mutagenesis in vitro. Both wild-type and mutant pigments were expressed, purified and regenerated as described previously [4]. The difference spectra were obtained by subtracting the dark spectra from the spectra after either hydroxylamine (VS pigments) or acid (UVS pigments) treatment. The λmax for each pigment was then determined by fitting a Govardovskii standard curve. (C) Amino acid sequence of grey squirrel SWS1 opsin aligned with mouse, guinea pig and bovine SWS1 opsins. Matching residues for the latter three sequences are identified by dots, gaps are denoted by dashes. The seven α helices' transmembrane regions are boxed and an arrow indicates site 86. The grey squirrel SWS1 opsin sequence has been deposited in GenBank (accession number DQ302163). Current Biology 2006 16, R81-R83DOI: (10.1016/j.cub.2006.01.045) Copyright © 2006 Elsevier Ltd Terms and Conditions

Figure 2 SWS1 opsins of flying squirrels. (A) Siberian and Northern flying squirrels. (B) Partial sequences of the SWS1 gene and sequence chromatograph alignments for grey squirrel, S. carolinensis, Siberian flying squirrel, P. volans, and Northern flying squirrel, G. sabrinus (GenBank accession numbers DQ302164 and DQ302165). The deletions found in flying squirrel sequences are indicated by dashes. The deleted amino acids are shown below the grey squirrel sequence using bovine rod opsin numbering. The amino acids below G. sabrinus sequence show a short stretch of substitutions arising from the frame shift mutation at position 300 (grey squirrel SWS1 opsin numbering). (C) The dark spectra for grey squirrel wild-type and the 9 base-pair deletion mutant showing failure of the latter to form a pigment. (Photograph for P. volans was kindly provided by Ilpo Hanski, and the photograph of G. sabrinus is from the Animal Picture Archive.) Current Biology 2006 16, R81-R83DOI: (10.1016/j.cub.2006.01.045) Copyright © 2006 Elsevier Ltd Terms and Conditions