Amylase in the hepatopancreas of a euryhaline burrowing crab: characteristics and modulation

Authors : ANTONELA ASARO, ROBERTO PAGGI, ROSANA DE CASTRO, ALEJANDRA LOPEZ MAÑANES

Pages : 443-453

View : 17 | Download : 7

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :In spite of its inherent physiological importance, studies on the occurrence, characteristics, and modulation of amylase in euryhaline crabs are lacking. We investigated the occurrence of amylase forms and the effect of acclimation to different salinities on their number and made a partial purification and characterization of the major form present in the hepatopancreas of Neohelice granulata. Zymogram analysis revealed 5 amylase forms in crabs acclimated to 35 psu insert ignore into journalissuearticles values(seawater); and 37 psu, and an additional band at 10 psu, but with a major form insert ignore into journalissuearticles values(29 kDa); in all cases, which was partially purified and characterized. Amylolytic activity was maximal between 30 and 40 °C; maintained at high NaCl concentrations insert ignore into journalissuearticles values(up to 4 M);; increased by 5 mM K+, Li+, Co2+, and Mg2+ insert ignore into journalissuearticles values(36%-45%);; inhibited by Cu2+, Zn2+, Cd2+, Fe2+, and Mn2+ insert ignore into journalissuearticles values(92.4% and 23.7%);; not affected by Ni2+ or Ba2+; and enhanced almost 100% by Ca2+. Amylase exhibited Michaelis-Menten kinetics insert ignore into journalissuearticles values(starch: Km = 1.24 mg mL-1; glycogen: Km = 16.19 mg mL-1);. The potential physiological significance and relationship to habitat conditions of the extra form in low salinity and the biochemical characteristics of the partially purified amylolytic activity insert ignore into journalissuearticles values(halotolerant, differential sensitivity to ions, capability to hydrolyze starch and glycogen); are discussed.
Keywords : Phenotypic flexibility, amylolytic activity, digestive tract, environment, euryhaline crabs