Expansion of voltage-dependent Na+ channel gene family in early tetrapods coincided with the emergence of terrestriality and increased brain complexity
MetadataShow full item record
Mammals have 10 voltage-dependent sodium (Nav) channel genes. Nav channels are expressed in different cell types with different sub-cellular distributions and are critical for many aspects of neuronal processing. The last common ancestor of teleosts and tetrapods had four Nav channel genes presumably on four different chromosomes. In the lineage leading to mammals a series of tandem duplications on two of these chromosomes more than doubled the number of Nav channel genes. It is unknown when these duplications occurred, whether they occurred against a backdrop of duplication of flanking genes on their chromosomes, or as an expansion of ion channel genes in general. We estimated key dates of the Nav channel gene family expansion by phylogenetic analysis using teleost, elasmobranch, lungfish, amphibian, avian, lizard, and mammalian Nav channel sequences, as well as chromosomal synteny for tetrapod genes. We tested, and exclude, the null hypothesis that Nav channel genes reside in regions of chromosomes prone to duplication by demonstrating the lack of duplication or duplicate retention of surrounding genes. We also find no comparable expansion in other voltage dependent ion channel gene families of tetrapods following the teleost-tetrapod divergence. We posit a specific expansion of the Nav channel gene family in the Devonian and Carboniferous periods when tetrapods evolved, diversified, and invaded the terrestrial habitat. During this time the amniote forebrain evolved greater anatomical complexity and novel tactile sensory receptors appeared. The duplication of Nav channel genes allowed for greater regional specialization in Nav channel expression, variation in sub-cellular localization, and enhanced processing of somatosensory input.
Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Molecular Biology and Evolution 28 (2011): 1415-1424, doi:10.1093/molbev/msq325.
Showing items related by title, author, creator and subject.
Burbach, J. Peter H.; Hellemons, Anita J. C. G. M.; Grant, Philip; Pant, Harish C. (The Company of Biologists, 2015-06-26)Homeodomain transcription factors regulate development of embryos and cellular physiology in adult systems. Paired-type homeodomain genes constitute a subclass that has been particularly implicated in establishment of ...
Koike-Tani, Maki; Tani, Tomomi; Mehta, Shalin B.; Verma, Amitabh; Oldenbourg, Rudolf (2013-05)The polarized light microscope reveals orientational order in native molecular structures inside living cells, tissues, and whole organisms. Therefore, it is a powerful tool to monitor and analyze the early developmental ...
Organohalogen contaminants and metabolites in cerebrospinal fluid and cerebellum gray matter in short-beaked common dolphins and Atlantic white-sided dolphins from the western North Atlantic Montie, Eric W.; Reddy, Christopher M.; Gebbink, Wouter A.; Touhey, Kathleen M.; Hahn, Mark E.; Letcher, Robert J. (2009-03-12)Concentrations of several congeners and classes of organohalogen contaminants (OHCs) and/or their metabolites, namely organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), hydroxylated-PCBs (OH-PCBs), ...