Ammonia excretion in the marine polychaete Eurythoe complanata (Annelida)

Autor(en): Thiel, Daniel
Hugenschuett, Maja
Meyer, Heiko
Paululat, Achim 
Quijada-Rodriguez, Alex R.
Purschke, Guenter 
Weihrauch, Dirk
Stichwörter: ACID-BASE REGULATION; ACTIVE EXCRETION; AEDES-AEGYPTI; AMTs; Biology; cAMP; CRAB CARCINUS-MAENAS; GILL EPITHELIUM; Gill morphology; H+-ATPASE; HEA; HIGH ENVIRONMENTAL AMMONIA; Life Sciences & Biomedicine - Other Topics; NITROGEN-EXCRETION; PROTEIN; RH GLYCOPROTEINS; V-ATPase
Erscheinungsdatum: 2017
Herausgeber: COMPANY OF BIOLOGISTS LTD
Journal: JOURNAL OF EXPERIMENTAL BIOLOGY
Volumen: 220
Ausgabe: 3
Startseite: 425
Seitenende: 436
Zusammenfassung: 
Ammonia is a toxic waste product from protein metabolism and needs to be either converted into less toxic molecules or, in the case of fish and aquatic invertebrates, excreted directly as is. In contrast to fish, very little is known regarding the ammonia excretion mechanism and the participating excretory organs in marine invertebrates. In the current study, ammonia excretion in the marine burrowing polychaete Eurythoe complanata was investigated. As a potential site for excretion, the 100-200 mu m long, 30-50 mu m wide and up to 25 mu m thick dentrically branched, well ventilated and vascularized branchiae (gills) were identified. In comparison to the main body, the branchiae showed considerably higher mRNA expression levels of Na+/K+-ATPase, V-type H+-ATPase, cytoplasmic carbonic anhydrase (CA-2), a Rhesus-like protein, and three different ammonia transporters (AMTs). Experiments on the intact organism revealed that ammonia excretion did not occur via apical ammonia trapping, but was regulated by a basolateral localized V-type H+-ATPase, carbonic anhydrase and intracellular cAMP levels. Interestingly, the V-type H+-ATPase seems to play a role in ammonia retention. A 1 week exposure to 1 mmol l(-1) NH4Cl (HEA) did not cause a change in ammonia excretion rates, while the three branchial expressed AMTs showed a tendency to be down-regulated. This indicates a shift of function in the branchial ammonia excretion processes under these conditions.
ISSN: 00220949
DOI: 10.1242/jeb.145615

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