2005 Fiscal Year Final Research Report Summary
Roles of Water Channel, Aquaporins, in Water Adaptation of Amphibians
| Project/Area Number |
16570052
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphology/Structure
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| Research Institution | Shizuoka University |
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Principal Investigator |
TANAKA Shigeyasu Shizuoka University, Department of Biology, Professor, 理学部, 教授 (90146233)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Masakazu Shizuoka University, Department of Biology, Associate Professor, 理学部, 助教授 (60280913)
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| Project Period (FY) |
2004 – 2005
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| Keywords | water channel / aquaporin / arginine vastotocin / hydrin / urinarly bladder / skin / immunocytochemistry / anuran amphibians |
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| Research Abstract |
This study was conducted to elucidate molecular and cellular mechanisms and molecular diversity of a water channel, aquaporin (AQP) in the water absorption of anuran amphibians, based on information about three kinds of Hyla AQPs (AQP-h1,AQP-h2, and AQP-h3) identified previously.
1.Expression of AQP-h2 and AQP-h3 in the pelvic ventral skins appeared first in the climax during metamorphosis, and was consistent with the expression of V_2 type AVT receptor.
2.We examined the roles of phosphorylated AQP in the membrane traffic of the urinary bladder. AQP-h2 was phosphorylated in cytoplasmic vesicles and then translocated to the apical membrane, indicating the phosphorylation of AQP is essential for translocation of the AQP-bearing vesicles.
3.We cloned a cDNA encoding AQP expressed in the basolateral membrane of skin granular cells, and named its protein AQP-3BL. This AQP seems to be involved in movement of water from intracellular matrix to the extracellular fluid.
4.Hydrins are intermediates formed during the intracellular processing of pro-vasotocin (AVT). Hydrins showed an ability to move AQP-h2 and AQP-h3 to the apical membrane. Water absorption in order of potency was as follows : AVT>hydrin 2>hydrin 1.
5.The AQP homologues in several anurans adapted to different habitats showed that all anurans, including aquatic species, possess an AQP-h2 homologue in their urinary bladder and an AQP-h3 homologue in their ventral skin. We also found that an AQP-h2 homologue was expressed in the ventral skin of arboreal and terrestrial species. These 2 species may need two kinds of AQP homologues to absorb more water through their ventral skin and to adapt to their dray environments. Thus, both AQP-h2 and AQP-h3 homologues play a key role as AVT-regulated AQPs in general mechanism of water balance to allow anuran amphibians to adapt to their habitats, especially to the dry land.
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Research Products
(16 results)
