“Amylase and maltase activities in hepatopancreas of Cyrtograpsus angulatus: Response to environmental salinity”

ASARO, A.; DEL VALLE, J.C; LÓPEZ MAÑANES, A,A.

Encuentro; Eleventh Multidisciplinary Workshop Argentine Biology; 2009

6.AMYLASE AND MALTASE ACTIVITIES IN HEPATOPANCREASOF Cyrtograpsus angulatus: RESPONSE TOENVIRONMENTAL SALINITYAsaro A1, del Valle JC, López Mañanes AA1,2.1Dpto Biología, FCEyN, UNMDP, Mar del Plata. 2CONICET.E-mail: antonela_asaro@hotmail.comLittle is known about biochemical digestive physiology in euryhalinecrabs. The aim of this work was to study biochemical characteristicsand the response to environmental salinity of amylase(Amy) and maltase (Mal) activities in hepatopancreas (H) of C.angulatus. Adult males were acclimated 10 days in 35‰ salinity(S) (characterization) or 35‰ and 10‰S (salinity effect). Thesupernatant (10000xg 15min) from an hepatopancreas homogenate(0.1M Tris-HCl, pH 7.4) (4ml buffer x g of tissue-1) wasused. Amy activity (μgmaltose x min-1 x mg protein-1) was assayedby hydrolysis of starch (St) in 50mM phosphate 30ºC (pHcurve: 5.2-7.0, St=15mg/ml; substrate curve: St=0.06-17.97mg/ml, pH=5.2; salinity: St=15mg/ml, pH=5.2). Mal activity(μgglucose x min-1 x mgprotein-1) was assayed by hydrolysis ofmaltose (M) 0.1 M maleate/OHNa 30ºC (pH curve: 3.5-8.3,M=28mM; substrate curve: M=2.8-42mM, pH=5.2; salinity:M=42mM, pH=5.2). Both activities were high over a wide rangeof pH and exhibited Michaelis-Menten kinetics (Amy: Km(mg/ml)=0.11±0.04; Mal: Km(mM)=8.08±3.96). In 35‰ S, Amy(6,619.25±976.25) and Mal (595.57±110.87) activities were high.In 10‰ S, both activities were lower (about 49%) (Amy: ANOVA,F=7.58, p=0.025; Mal: ANOVA, F=6.66, p=0.033). The resultssuggest the role of amylases and maltase activities in mechanismsof adjustment related to osmorregulatory status.