Effects of salinity acclimation and eyestalk ablation on Na+, K+, 2Cl− cotransporter gene expression in the gill of Portunus trituberculatus:a molecular correlate for salt-tolerant trait

Abstract

The Na− cotransporter (NKCC) is an important gene in ion transport. In order to elucidate its function, and regulatory mechanisms, in salinity acclimation, the complete cDNA sequence of NKCC (4218 bp) from Portunus trituberculatus (PtNKCC) was first cloned and characterized. It was found to encode 1055 amino acids containing conserved AA-permease and SLC12 motifs. Results show that PtNKCC is expressed to the greatest extent in gills. High salinity stress exposure led to significant increases (9.6-fold) of PtNKCC mRNA expression in the gills 12 h after treatment, declining to less than the levels seen in the control group between 48 and 72 h. During low salinity stress, expression levels of PtNKCC in gills were found to be upregulated at each sampling time, reaching their peak after 6 h (a 12.4-fold increase). Eyestalk ablation also triggered an 11.3-fold increase in PtNKCC mRNA, while re-injection with eyestalk homogenates significantly reduced the expression of PtNKCC mRNA. Four single nucleotide polymorphisms (SNPs) were detected in the PtNKCC open reading frame, and one SNP was associated with salt tolerance. Our results indicate that PtNKCC plays an important role in the salinity acclimation of P. trituberculatus, while there may be a compound present in the XOSG that inhibits the expression of PtNKCC.

Osmoregulation, bioenergetics and oxidative stress in coastal marine invertebrates: raising the questions for future research

“…Gómez-Angelats and Cidlowski, 2002). The opposite reaction is observed in the case of a hypotonic challenge; mechanisms to control water fluxes into cells include: (1) decreases in membrane permeability to water, (2) changes in the concentration of osmotic effectors (amino acids and organic ions) (reviewed by Pierce, 1982) to decrease internal osmolality, (3) changes in the expression of channels or active membrane carriers -such as Na + /K + -ATPase (NKA) or Na + /K + /Cl − cotransporters, or carbonic anhydrase (Henry et al, 2002;Lovett et al, 2006;Lv et al, 2016) -and (4) the production of ammonia (Rosas et al, 1999), among others (Łapucki and Normant, 2008). Animals exposed to salinity stress must increase their energy expenditure to successfully acclimate to the stressor and ensure cellular protection (Sokolova et al, 2012b).…”

Salt transport by the gill Na+-K+-2Cl-symporter in palaemonid shrimps: exploring physiological, molecular and evolutionary landscapes

“…In the freshwater species M. australiense , gill NKCC mRNA expression increases 1.7-fold and 2-fold after 24 h exposure to 5 or 10 ‰S, respectively, (Moshtaghi et al 2018). Transcriptional regulation of the gill NKCC gene has been explored in crabs like Neohelice granulata , (Luquet et al 2005), Carcinus maenas (Towle et al 2011), Callinectes sapidus , (Havird et al 2016) and Portunus trituberculatus (Lv et al 2016), and in the atyid shrimp Halocaridina rubra (Havird et al 2014). Expression increases 60-fold in Neohelice granulata (Luquet et al 2005) and 9.6-fold in P. trituberculatus (Lv et al 2016) on exposure to 45 ‰S.…”

“…Transcriptional regulation of the gill NKCC gene has been explored in crabs like Neohelice granulata , (Luquet et al 2005), Carcinus maenas (Towle et al 2011), Callinectes sapidus , (Havird et al 2016) and Portunus trituberculatus (Lv et al 2016), and in the atyid shrimp Halocaridina rubra (Havird et al 2014). Expression increases 60-fold in Neohelice granulata (Luquet et al 2005) and 9.6-fold in P. trituberculatus (Lv et al 2016) on exposure to 45 ‰S. Similarly, gill NKCC1 mRNA expression in the European yellow eel (Cutler and Cramb 2002), sea bass (Lorin-Nebel et al 2006) and Atlantic salmon (Mackie et al 2007) are higher when in seawater compared to fish acclimated to fresh water.…”

“…With regard to crustacean osmoregulation, molecular studies on membrane transporter localization, activity and expression are helping to elucidate the mechanisms of salt transport (Péqueux 1995, Kirschner 2004, Freire et al 2008a, McNamara and Faria 2012). NKCC mRNA expression increases in the posterior gills of the semi-terrestrial estuarine crab Neohelice granulata exposed to either dilute or concentrated seawater (Luquet et al 2005) in contrast to the swimming crab Portunus trituberculus in which expression is down regulated (Lv et al 2016). NKCC mRNA expression is up regulated in the gills of the hololimnetic freshwater shrimp Macrobrachium australiense when challenged by increased salinity (Moshtaghi et al 2018).…”

O cotransportador Na⁺, K⁺, 2Cl^- e a secreção de cloreto branquial em camarões Palaemonidae (Decapoda, Crustacea): padrões moleculares, fisiológicos e evolutivos

“…Apesar de ainda muito escassos, existem alguns dados que relacionam a expressão do cotransportador NKCC com o mecanismo de secreção e/ou absorção de sal em crustáceos (Luquet et al 2005;Towle et al 2011;Barman et al 2012;Havird et al 2014;2016;Lv et al 2016;Moshtaghi 2016). A caracterização da expressão gênica do NKCC em diferentes fases do ciclo de muda foi descrita no caranguejo Scylla paramamosain, atribuindo ao simportador um papel importante na absorção iônica pelas brânquias, especialmente nos estágios pósmuda (Xu et al 2017).…”