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This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/C1867    most recent 00514.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Huang, C. G. Articles by Strange, K. Search for Related Content PubMed PubMed Citation Articles by Huang, C. G. Articles by Strange, K.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Functional analysis of the aquaporin gene family in Caenorhabditis elegans

¹Departments of Anesthesiology and Pharmacology, Vanderbilt University, Nashville, Tennessee; ²Department of Biological Chemistry, Johns Hopkins University, Baltimore, Maryland; and ³Duke University School of Medicine, Durham, North Carolina

Submitted 3 October 2006 ; accepted in final form 9 January 2007

Aquaporin channels facilitate the transport of water, glycerol, and other small solutes across cell membranes. The physiological roles of many aquaporins remain unclear. To better understand aquaporin function, we characterized the aquaporin gene family in the nematode Caenorhabditis elegans. Eight canonical aquaporin-encoding genes (aqp) are present in the worm genome. Expression of aqp-2, aqp-3, aqp-4, aqp-6, or aqp-7 in Xenopus oocytes increased water permeability five- to sevenfold. Glycerol permeability was increased three to sevenfold by expression of aqp-1, aqp-3, or aqp-7. Green fluorescent protein transcriptional and translational reporters demonstrated that aqp genes are expressed in numerous C. elegans cell types, including the intestine, excretory cell, and hypodermis, which play important roles in whole animal osmoregulation. To define the role of C. elegans aquaporins in osmotic homeostasis, we isolated deletion alleles for four aqp genes, aqp-2, aqp-3, aqp-4, and aqp-8, which are expressed in osmoregulatory tissues and mediate water transport. Single, double, triple, and quadruple aqp mutant animals exhibited normal survival, development, growth, fertility, and movement under normal and hypertonic culture conditions. aqp-2;aqp-3;aqp-4;aqp-8 quadruple mutants exhibited a slight defect in recovery from hypotonic stress but survived hypotonic stress as well as wild-type animals. These results suggest that C. elegans aquaporins are not essential for whole animal osmoregulation and/or that deletion of aquaporin genes activates mechanisms that compensate for loss of water channel function.

water channel; osmoregulation