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Facilitated NaCl Uptake in the Highly Developed Bundle of the Nephron in Japanese Red Stingray Hemitrygon akajei Revealed by Comparative Anatomy and Molecular Mapping
- Source :
- Zoological Science. 37:1
- Publication Year :
- 2020
- Publisher :
- Zoological Society of Japan, 2020.
-
Abstract
- Batoidea (rays and skates) is a monophyletic subgroup of elasmobranchs that diverged from the common ancestor with Selachii (sharks) about 270 Mya. A larger number of batoids can adapt to low-salinity environments, in contrast to sharks, which are mostly stenohaline marine species. Among osmoregulatory organs of elasmobranchs, the kidney is known to be dedicated to urea retention in ureosmotic cartilaginous fishes. However, we know little regarding urea reabsorbing mechanisms in the kidney of batoids. Here, we performed physiological and histological investigations on the nephrons in the red stingray (Hemitrygon akajei) and two shark species. We found that the urine/plasma ratios of salt and urea concentrations in the stingray are significantly lower than those in cloudy catshark (Scyliorhinus torazame) under natural seawater, indicating that the kidney of stingray more strongly reabsorbs these osmolytes. By comparing the three-dimensional images of nephrons between stingray and banded houndshark (Triakis scyllium), we showed that the tubular bundle of stingray has a more compact configuration. In the compact tubular bundle of stingray kidney, the distal diluting tubule was highly developed and frequently coiled around the proximal and collecting tubules. Furthermore, co-expression of NKAα1 (Na+/K +-ATPase) and NKCC2 (Na+- K+-2Cl– cotransporter 2) mRNAs was prominent in the coiled diluting segment. These findings imply that NaCl reabsorption is greatly facilitated in the stingray kidney, resulting in a higher reabsorption rate of urea. Lowering the loss of osmolytes in the glomerular filtrate is likely favorable to the adaptability of batoids to a wide range of environmental salinity.
- Subjects :
- 0106 biological sciences
0301 basic medicine
biology
urogenital system
Reabsorption
Zoology
Nephron
biology.organism_classification
010603 evolutionary biology
01 natural sciences
Catshark
Scyliorhinus torazame
03 medical and health sciences
030104 developmental biology
medicine.anatomical_structure
Houndshark
Stingray
medicine
Batoidea
Animal Science and Zoology
Stenohaline
Subjects
Details
- ISSN :
- 02890003
- Volume :
- 37
- Database :
- OpenAIRE
- Journal :
- Zoological Science
- Accession number :
- edsair.doi...........c1a7a8e87ae1ece78625eb20c8e9e41f