Identification of the role of Rh protein in ammonia excretion of swimming crab Portunus trituberculatus

Abstract

In , a full-length cDNA of Rhesus-like glycoprotein (Rh protein), encoding the entire 478 amino acid protein, has been identified in gills, and plays an essential role in ammonia (NH/NH ) excretion. Phylogenetic analysis of Rh-like proteins from crabs was clustered, showing high conservation of the ammonium transporter domain and transmembrane segments essential to the function of Rh protein. Rh protein of (Rh) was detected in all tested tissues, and showed the highest expression in the gills. To further characterize the role of Rh in ammonia metabolism and excretion, double-stranded RNA-mediated RNA interference ofRh was employed. Knockdown of Rh upregulated mRNA expression of ammonia excretion-related genes encoding aquaporin (AQP), K channels and vesicle-associated membrane protein (VAMP), increased the activity of Na/K-ATPase (NKA) and V-type H-ATPase (V-ATPase), and initially reduced then elevated the expression of the Na/H-exchanger (NHE). dsRNA-mediated reduction in Rh significantly reduced ammonia excretion rate and increased ammonia and glutamine (Gln) levels in the hemolymph, together with an increase of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) activity, indicating a central role forRh in ammonia excretion and detoxification mechanisms. Taken together, we conclude that Rh protein is a primary contributor to ammonia excretion of , which may be the basis of their ability to inhabit benthic water with high ammonia levels.

Targeted metagenomic recovery of four divergent viruses reveals shared and distinctive characteristics of giant viruses of marine eukaryotes

“…However, based on family members that have been functionally characterized, specificity is high for the target substrate, and not for other monocationic cations, at least in plants and yeast [115]. In contrast to Amt and Mep, findings are less clear for Rh proteins [116], which have also been implicated in CO 2 transport [117,118]. Rhesus factor proteins have mostly been found in eukaryotes, of which those of mammalian origin have been most studied [110,111].…”

Comparative Transcriptomic and Proteomic Analysis of Exopalaemon carinicauda in Response to Alkalinity Stress

“…Ali et al (2015) suggested that carbonic anhydrase is involved in the response to changes in pH and in systemic acid-base balance in freshwater crayfish. Ammonium transporter Rh involved in the ammonia excretory process have been identified in crustaceans (Si et al, 2018). It has been reported that the expression of Rh protein increased significantly in the gill of Eriocheir sinensis, Portunus trituberculatus, and L. vannamei after abiotic stress, and ammonia excretion was inhibited after Rh protein knockdown in Caenorhabditis elegans and P. trituberculatus (Martin et al, 2011;Ren et al, 2015;Aida et al, 2016;Si et al, 2018).…”

“…Ammonium transporter Rh involved in the ammonia excretory process have been identified in crustaceans (Si et al, 2018). It has been reported that the expression of Rh protein increased significantly in the gill of Eriocheir sinensis, Portunus trituberculatus, and L. vannamei after abiotic stress, and ammonia excretion was inhibited after Rh protein knockdown in Caenorhabditis elegans and P. trituberculatus (Martin et al, 2011;Ren et al, 2015;Aida et al, 2016;Si et al, 2018). The Na + /H + exchanger in gill cells creates an electrochemical gradient for regulation osmotic pressure, which can help aquatic organisms balance the changes of osmotic pressure in vivo (Castaldo et al, 2020).…”

Multifaceted ammonia transporters

“…Multiple and pairwise alignments performed using the ClustalW and DNASIS programs (not presented) also confirms the significant similarity of these transporter structures. The amino acid sequence similarity of all ammonia transporters ranges from 15 to 92% for different species, with stable preservation of the topology of conservative functional sites (Si et al 2018).…”