Osmoregulatory performance and immunolocalization of Na+/K+-ATPase in the branchiopod Artemia salina from the Sebkha of Sidi El Hani (Tunisia)

Abstract

Artemia salina is an extremophile species that tolerates a wide range of salinity, especially hypertonic media considered lethal for the majority of other aquatic species. In this study, A. salina cysts were hatched in the laboratory and nauplii were acclimated at three different salinities (60, 139 and 212 ppt). Once in the adult phase, their hemolymph osmolality was measured. The animals were strong hypoosmoregulators in the entire range of tested salinities, with up to 10 fold lower hemolymph osmolalities than their surrounding environment. Immunostaining of Na+/K+-ATPase was done on sections and on whole body mounts of adults in order to localize the ionocytes in different organs. An intense Na+/K+-ATPase immunostaining throughout the cells was observed in the epithelium of the ten pairs of metepipodites. A positive immunoreactivity for Na+/K+-ATPase was also detected in the maxillary glands, in the epithelium of the efferent tubule and of the excretory canal, as well as in the anterior digestive tract. This study confirms the strong hypo-osmotic capacity of this species and affords an overview of the different organs involved in osmoregulation in A. salina adults. Abbreviations.

Tolerance at the genetic level of the brine shrimp Artemia salina to a wide range of salinity

“…However, the notable absence of acidic protein pro les in the brine shrimp Artemia was identical to other crustaceans in seawater. Thus, our transcriptomic analysis con rms that A. salina is a strict hyporegulator [24][25][26]61].…”

“…In crustaceans, the enzyme Na + /K + -ATPase serves to maintain sodium and potassium ion homeostasis across cell membranes [62][63][64][65]. Several studies have used the silver staining method to demonstrate that the metepipodites, digestive gut, and maxillary glands in A. salina exhibit high Na + /K + -ATPase activity under highly saline conditions [24,26,61]. This con rms that the enzyme Na + /K + -ATPase plays an essential role in A. salina osmoregulation at the genetic level.…”

“…A. salina is a lter feeder, consuming phytoplankton (e.g., Dunaliella) and prokaryotes in these high salinity waters. Thus, this extremophile species must be a strict osmoregulator, as it regularly ingests high salinity water along with prey [23][24][25][26]. Several studies report that an increase in salinity stimulates Na + /K + -ATPase activity in multiple organs (e.g., metepipodites, maxillary glands, and gut) of adult A. salina for the excretion of accumulated salts [23][24][25][26].…”

“…Thus, this extremophile species must be a strict osmoregulator, as it regularly ingests high salinity water along with prey [23][24][25][26]. Several studies report that an increase in salinity stimulates Na + /K + -ATPase activity in multiple organs (e.g., metepipodites, maxillary glands, and gut) of adult A. salina for the excretion of accumulated salts [23][24][25][26]. In addition, the hemolymph of A. salina is maintained at a constant ~ 300 mOsm/kg (9 psu salinity), which is similar to the osmolality of teleost shes, when exposed to a range of external high salinities [25,27].…”

Bazı Geofit Türlerin Biyoaktif Bileşiklerinin Tuzlu Su Karidesi (Artemia salina)'ne Karşı Toksisite Aktivitesinin Değerlendirilmesi

“…It can survive and improve, especially in a hypertonic environment, and can be found all over the world. It is one of the few organisms that can survive in the world's most saltwater lakes with microalgae and certain types of bacteria (Asem et al, 2010;Johari et al, 2019;Sellami et al, 2020). It is highly preferred both scientifically and in aquaculture due to its structures that have good nutritional value, can be readily available, low cost, high reproduction rate, easy to cultivate, and are not easily affected by environmental conditions (McLaughlin et al, 1991;Yun et al, 2020).…”