Digestive flexibility in a euryhaline crab from a SW Atlantic coastal lagoon: alkaline phosphatase activity sensitive to salinity in the hepatopancreas

Abstract

We studied biochemical characteristics and the response to low salinity at short and long-term after feeding of alkaline phosphatase (AP) activity in hepatopancreas of the osmoregulator crab Neohelice granulata from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina) (37°32′–37°45′S 57°19′–57°26′W). The hepatopancreas exhibited a levamisole-insensitive and a levamisole-sensitive AP activity with distinct characteristics. Levamisole-insensitive activity was similar within the range of pH 7.4–9.0 and exhibited a Michaelis–Menten kinetics. Levamisole-sensitive AP activity appeared to be maximal at pH 8.5 and appeared to exhibit an allosteric kinetics. In crabs acclimated to 10 psu (hyper-regulation conditions) levamisole-insensitive and levamisole-sensitive AP activity increased (about 16-fold) over time from short term (2–4 h) to long term (120 h) after feeding while no changes occurred in crabs acclimated to 35 psu (osmoconforming conditions). The changes of AP activity along with the higher values at 120 h after feeding in 10 psu compared with those in 35 psu, and the concomitant changes in proteolytic activity, suggest a role of AP in digestive and metabolic adjustments at the biochemical level upon hyper-regulatory conditions.

Amylase in the hepatopancreas of a euryhaline burrowingcrab: characteristics and modulation

“…The differences in the number of amylase forms present in the hepatopancreas of crustaceans have been associated with variations in environmental and/or physiological factors (Borowsky, 1984;Le Moullac et al, 1997;Perera et al, 2008aPerera et al, , 2008bCastro et al, 2012). N. granulata behaves as a hyper/hyporegulator since it exhibits hemolymph osmolarity values higher and lower than those of the corresponding external medium upon acclimation to 6-10 psu and 37-60 psu, respectively, while it osmoconforms at 35 psu (Asaro et al, 2011;Pinoni et al, 2013;Michiels et al, 2015a;Pinoni et al, 2015; this work, Table). The additional 30 kDa species found by zymogram analysis in the hepatopancreas from crabs acclimated to low salinity (10 psu) (hyperregulation conditions) (Figure 1b) suggests that mechanisms of modulation at the molecular level occur, which could lead to the higher total amylase activity detected by biochemical analysis.…”

“…The modulation of digestive enzyme activities in the hepatopancreas (e.g., amylase) in response to different environmental salinity could lead to adjustments in the digestive capacity for specific substrates (starch/glycogen) and therefore in the availability of key metabolites (i.e. glucose) (Romano and Zeng, 2012;Michiels et al, 2013Michiels et al, , 2015aPinoni et al, 2015). However, studies at the molecular level, as we pointed out above, are lacking.…”

“…modulation of key digestive enzymes) in response to variations in environmental factors (del Valle et al, 2004(del Valle et al, , 2006Karasov et al, 2011;Karasov and Douglas, 2013). In some species of intertidal euryhaline crabs, biochemical adaptation to low and high salinity involves adjustments in various tissues and organs such as the hepatopancreas, although the mechanisms are still not fully understood from a metabolic perspective (Pinoni et al, 2005(Pinoni et al, , 2008Pinoni and López Mañanes, 2009;Asaro et al, 2011;Romano and Zeng, 2012;Romano et al, 2014;Michiels et al, , 2015aPinoni et al, 2013Pinoni et al, , 2015. The modulation of digestive enzyme activities in the hepatopancreas (e.g., amylase) in response to different environmental salinity could lead to adjustments in the digestive capacity for specific substrates (starch/glycogen) and therefore in the availability of key metabolites (i.e.…”

“…In the Mar Chiquita coastal lagoon (Argentina), this crab successfully occupies the whole intertidal area, where it is exposed to a broad range of environmental salinities (Spivak et al, 1994;Luppi et al, 2013). Previous work of our laboratory showed that complex and integrative responses occur upon acclimation to low and high salinity (López Mañanes et al, 2000;Schleich et al, 2001;Pinoni et al, 2005Pinoni et al, , 2013Pinoni et al, , 2015Pinoni and López Mañanes, 2009;Asaro et al, 2011;Michiels et al, 2015a). The aims of this work were to determine the occurrence of amylase forms in the hepatopancreas of the intertidal euryhaline crab N. granulata, to examine the effect of acclimation of crabs to low and high salinity on the pattern of amylase forms, and to determine biochemical characteristics of partially purified amylase.…”

The euryhaline crabUca tangerishowed metabolic differences to sex and environmental salinity

“…type of reserves, storage organs involved) are species-specific and depend on the type of osmotic challenge (Romano & Zeng, 2012; Pinoni et al ., 2013; Romano et al ., 2014). Hyper and hypo-osmoregulation can require different mechanisms which lead to differential adjustments in carbohydrates, protein and lipid metabolism (Michiels et al ., 2013, 2015; Pinoni et al ., 2013, 2015; Romano et al ., 2014). The possible occurrence of differential metabolic adjustments related to sex is poorly studied.…”