Amphibian aquaporins and adaptation to terrestrial environments: A review

Suzuki, Masakazu; Hasegawa, Takahiro; Ogushi, Yuji; Tanaka, Shigeyasu

doi:10.1016/j.cbpa.2006.12.021

Cited by 84 publications

(62 citation statements)

References 53 publications

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“…The tissue electrolyte content was diluted in nonperfused skin, indicating the circulation removed water as it was absorbed to prevent diminution of the osmotic gradient across the epidermis. Water absorption by anurans occurs in conjunction with a behavior, termed the water absorption response (16,26), during which the skin is pressed to a moist surface and there is a large increase in blood flow to the absorbing area of the seat patch (33,34), in conjunction with the insertion of AQPs into the apical membranes of the FRC layer of the skin (27). A better understanding of adaptations for semiterrestrial vs. semiaquatic species will require an understanding of all three parameters from a physiological and phylogenetic perspective.…”

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

“…Both AQP-h2 and AQP-h3 isoforms are anuran specific AQPs that are structurally distinct from mammalian AQP2 but similarly become inserted into the apical membrane of epithelial cells by antidiuretic hormone stimulation (27). The species differences in the expression and localization of AQP-h2-and AQP-h3-reactive AQPs in the skin raise interesting hypotheses in the context of recent phylogenetic analyses of anuran taxa.…”

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

“…AQP-h3 has been found in the ventral skin of Bufonid, Hylid, and Ranid species (20,27), suggesting this pattern of expression is a more pleisiomorphic characteristic. As noted above, we observed AQP-h3 immunoreactivity to be present in the pelvic, as well as hindlimb, skin of R. catesbeiana, while it was only present in the hindlimbs of R. japonica and R. nigromaculata.…”

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

“…(29). Thus, anurans possess both AQP-h2-and AQP-h3-like AQPs, which respond to AVT, like mammalian AQP2, but are classified into an anuran-specific type, AQPa2 by phylogenetic analyses (27,28). For Xenopus tropicalis, whose genome data are available in the Ensembl genome browser (http://www.…”

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

“…AQP-h2-like AQPs are also localized in the urinary bladder of Rana and Bufo species (20,27) and have been referred to as the "urinary bladder-type" amphibian AQP (20). The second isoform, AQPh3, was characterized from the ventral skin but not the urinary bladder of H. japonica (31).…”

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The water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins

Ogushi

Tsuzuki

Sato

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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Regions of specialization for water absorption across the skin of Bufonid and Ranid anurans were identified by immunohistochemistry and Western blot analysis, using antibodies raised against arginine vasotocin (AVT)-stimulated aquaporins (AQPs) that are specific to absorbing regions of Hyla japonica. In Bufo marinus, labeling for Hyla urinary bladder-type AQP (AQP-h2), which is also localized in the urinary bladder, occurred in the ventral surface of the hindlimb, pelvic, and pectoral regions. AQP-h2 was not detected in any skin regions of Rana catesbeiana, Rana japonica, or Rana nigromaculata. Hyla ventral skin-type AQP (AQP-h3), which is found in the ventral skin but not the bladder of H. japonica, was localized in the hindlimb, pelvic, and pectoral skins of Bufo marinus, in addition to AQP-h2. AQP-h3 was also localized in ventral skin of the hindlimb of all three Rana species and also in the pelvic region of R. catesbiana. Messenger RNA for AQP-x3, a homolog of AQP-h3, could be identified by RT-PCR from the hindlimb, pectoral, and pelvic regions of the ventral skin of Xenopus laevis, although AVT had no effect on water permeability. In contrast, 10 Ϫ8 M AVT-stimulated water permeability and translocation of AQP-h2 and AQP-h3 into the apical membrane of epithelial cells in regions of the skin of species where they had been localized by immunohistochemistry and Western blot analysis. Finally, water permeability of the hindlimb skin of B. marinus and all the Rana species was stimulated by hydrins 1 and 2 to a similar level as seen for AVT. The present data demonstrate species differences in the occurrence, distribution, and regulation of AQPs in regions of skin specialized for rapid water absorption that can be associated with habitat and also phylogeny. hindlimb skin; arginine vasotocin; immunohistochemistry; water permeability; frogs MANY ADULT ANURAN AMPHIBIANS do not drink through their mouth. Rather, they absorb water across their skin and form dilute urine that is stored in their urinary bladder and can be reabsorbed when foraging away from a hydration source (4, 5). Hillman et al. (14) refer to this water balance strategy as semiterrestrial to distinguish it from terrestrial species that are completely independent of water. The semiterrestrial classification applies to tree frogs in the family Hylidae and toads in the family Bufonidae that have been traditionally classified as arboreal and terrestrial, respectively, in that both have large urinary bladder capacity and specializations for rapidly rehydrating when water is available. Specifically, they utilize an area of skin in the posteroventral region of the body that is specialized for rapid water absorption from shallow water sources or moist substrates. This region, termed the pelvic patch or seat patch, extends laterally to the ventral surface of the hindlimbs and shows a pattern of elevations and grooves termed verrucae hydrophilicae (14). The seat patch is also an area where capillaries form intimate contact with the basement membrane that underli...

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Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

Section: Possible Expression Of New-type Aqps In the Ventral Pelvic Smentioning

confidence: 99%

mentioning

confidence: 99%

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The water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins

Ogushi

Tsuzuki

Sato

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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Aquaporins: Channels for the Molecule of Life

Hacke

Laur

2016

Encyclopedia of Life Sciences

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Liquid water has unique properties that make it a universal solvent. Water is an essential component of almost all physiological and biochemical reactions; therefore, its presence is required everywhere within an organism. The circulatory systems of animals and the vascular system of plants move fluids over long distances. In the tallest trees, water moves across a height gradient of 100 m or more, thereby connecting roots and distant leaves. On a cellular and tissue level, water movement is facilitated by intrinsic membrane proteins called aquaporins. These water channels are found in all life forms. Aquaporins have been mostly studied in mammals and plants, where water channels play important physiological roles. This article gives an overview of the discovery, structure and regulation of aquaporins. Their roles in different life forms are discussed. Key Concepts Water can diffuse through the lipid bilayer, but without aquaporins flow across membranes is slow. Aquaporins are integral membrane transport proteins, and they facilitate water movement in cells, tissues and entire organisms. A single water channel allows the passive passage of more than one billion water molecules per second. The aquaporin protein family is ancient, and aquaporins can be found in a wide range of organisms. Aquaporins appear to play important physiological roles in mammals, plants and other organisms.

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Osmoregulation by Vertebrates in Aquatic Environments

Lillywhite

Evans

2021

Encyclopedia of Life Sciences

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Because the salt concentration of body fluids in aquatic vertebrates differs from that of their environment, they face net influx or efflux of water and salt across their permeable skin or exposed membranes. In fishes, these diffusional movements of both salts and water largely involve the gills. Other vertebrates have less permeable body surfaces, but water and salts are gained in drinking that is incidental to eating prey, which also can be an important source of salt intake. Kidneys function importantly in freshwater fishes to remove excess water, and ions are actively transported inwards across gill tissue as well as acquired in food. Marine fishes tend to dehydrate in seawater, so they drink seawater to make up a water deficit and secrete excess salt across the gills. Marine elasmobranch fishes accumulate urea in body fluids to minimise the gradient for osmotic exchange and secrete excess ions via a specialised rectal gland that functions accessory to the kidney. In other vertebrates, inhabitants of fresh water must counteract a key problem of acquiring sufficient ions while excreting nitrogenous waste as ammonia or urea, whereas marine species must avoid excess salt intake while avoiding dehydration. Vertebrates without gills have evolved either extrarenal salt glands that excrete excess salt, or in the case of mammals, a specialised kidney that can excrete highly concentrated urine. Relatively few, non‐fish taxa drink seawater as a route for water gain, while most others have dependency on dietary, metabolic or free drinking water. Osmoregulation involves the maintenance of volume, distribution and ionic composition of body fluids in organisms. With the exception of hagfish, extant vertebrates maintain osmotic concentrations of body fluids at levels that are roughly one‐third that of seawater. Aquatic vertebrates living in fresh water must counteract excessive influx of water and losses of ions to the surrounding environment, whereas those living in marine environments tend to dehydrate and gain excess salt. Freshwater fishes eliminate excess water by means of producing a copious flow of dilute urine, while acquiring ions from surrounding water by transporter mechanisms located in the gills. Marine fishes acquire needed water by drinking seawater and excreting excess salt gained by diffusion and drinking by transport mechanisms in the gills. Marine vertebrates other than fishes and mammals have evolved extrarenal salt glands that excrete excess salts, and water is gained largely from dietary, metabolic and freshwater drinking sources. Marine mammals excrete salt loads and urea from kidneys that have effective concentrating abilities, while gaining water from diet and metabolism.

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Amphibian aquaporins and adaptation to terrestrial environments: A review

Cited by 84 publications

References 53 publications

The water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins

The water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins

Aquaporins: Channels for the Molecule of Life

Osmoregulation by Vertebrates in Aquatic Environments

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