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Molecular characterization and embryonic expression of innexins in the leech Hirudo medicinalis

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Abstract

Gap junctions are direct intercellular channels that permit the passage of ions and small signaling molecules. The temporal and spatial regulation of gap junctional communication is, thus, one mechanism by which cell interactions, and hence cell properties and cell fate, may be regulated during development. The nervous system of the leech, Hirudo medicinalis, is a particularly advantageous system in which to study developmental mechanisms involving gap junctions because interactions between identified cells may be studied in vivo in both the embryo and the adult. As in most invertebrates, gap junctions in the leech are composed of innexin proteins, which are distantly related to the vertebrate pannexins and are encoded by a multi-gene family. We have cloned ten novel leech innexins and describe the expression of these, plus two other previously reported members of this gene family, in the leech embryo between embryonic days 6 and 12, a period during which the main features of the central nervous system are established. Four innexins are expressed in neurons and two in glia, while several innexins are expressed in the excretory, circulatory, and reproductive organs. Of particular interest is Hm-inx6, whose expression appears to be restricted to the characterized S cell and two other neurons putatively identified as presynaptic to this cell. Two other innexins also show highly restricted expressions in neurons and may be developmentally regulated.

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Acknowledgements

This work was supported in part by National Institute of Health Grant NS043546 and by the University of California, San Diego funds. We thank Dr. Alejandro Sanchez for his help with the sense in situ hybridization control experiments.

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Correspondence to Eduardo R. Macagno.

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Communicated by DA Weisblat

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Supplementary Fig. 1

Figa

Multiple sequence alignment to show the translated protein sequence of the leech Innexin genes discussed in the text. Identical residues are shaded. Note that Hm-inx7, Hm-inx8 and Hm-inx10 are partial sequences and only the C-terminal portion of the sequence is known. Accession numbers of the corresponding cDNA sequences are as follows: Hm-inx1 = AJ512833; Hm-inx2 = AJ512834; Hm-inx3 = DQ228700; Hm-inx4 = DQ228701; Hm-inx5 = DQ228702; Hm-inx6 = DQ228703; Hm-inx7 = DQ228704; Hm-inx8 = DQ228705; Hm-inx9 = DQ228706; Hm-inx10 = DQ228707; Hm-inx11 = DQ228708; Hm-inx12 = DQ228709

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Dykes, I.M., Macagno, E.R. Molecular characterization and embryonic expression of innexins in the leech Hirudo medicinalis . Dev Genes Evol 216, 185–197 (2006). https://doi.org/10.1007/s00427-005-0048-1

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