Digestive flexibility at the biochemical level in the euryhaline crab Neohelice granulata from Mar Chiquita coastal lagoon: effect of an abrupt change of salinity on lipase and proteolytic activity in the hepatopancreas”

MICHIELS, M.S.; DEL VALLE, J.C; LÓPEZ MAÑANES, A,A.

Congreso; XIII Congress- XXXI Annual Meeting Rosario Biology Society; 2011

Studies about possible digestive adjustments at the biochemical level associated to osmoregulatory flexibility of euryhaline crabs are lacking. The aim of this work was to study the effect of an abrupt salinity change on lipase (Lip) and proteolytic (Prot) activities in hepatopancreas. Male crabs maintained for 10 days in 37‰ salinity (hyporegulation conditions) were transferred (To) to 10‰S (hyperregulation conditions). Lip and Prot were determined at To and at 2, 4 and 24 h after transfer (Controls: Crabs maintained at 37 and 10‰S throughout the experimental period). 10000xg 15 min supernatant was used as enzyme extract (homogenization medium: Tris-HCl 0.1M, pH 7.4) (4 ml x g tissue-1). Lip (μmoles pNP x min-1 x mg protein-1) was assayed by measuring pNPpalmitate hydrolysis (0.7 mM) in 50 mM Tris/HCl 50mM pH 8.5 at 37ºC. Prot (enzyme units×h-1×mg protein-1) was assayed by measuring azocasein hydrolysis (1% p/v) in Tris-HCl, 0.1M, pH 7.5. At 2 and 4 h, Lip (2 h= 40.6 ± 12.8; 4h= 40.1 ± 10.9) and Prot (2h= 4.8 ± 0.9; 4h= 4.1 ± 0.6) were similar to To (Lip= 38.6 ± 15.1; Prot= 4.5 ± 0.4)(n= 5; Anova, p