RESUMO
In Sub-Saharan Africa, Lagenaria siceraria is an oleaginous cucurbit widely consumed for its edibleseeds. These seeds were previously categorized as good enzyme sources, including four non-specific acidphosphatases isolated and designated as BLsAP1, BLsAP2, RLsAP1, and RLsAP2. In this study, we investigateon the kinetic and thermodynamic characteristics of these biocatalysts in order to evaluate their thermostability.Thermal inactivation was carried out in the temperature range of 55°C to 80°C from 5 to 60 minutes. The resultsrevealed that thermal inactivation of studied acid phosphatases follows first order kinetics. At their optimumtemperatures, these enzymes showed high half-lives ranging from 169.06 to 495.10 minutes and D valuesfrom 561.71 to 1,645.03 minutes. Moreover, they exhibited high activation energies (from 155.08 to 200.55kJ/mol) and average enthalpy values (from 152.23 to 197.74 kJ.mol−1) suggesting their good thermostability.The comparison of all these values revealed that the two acid phosphatases (RLsAP1 and RLsAP2) from theround-fruited cultivar of L. siceraria showed better thermal stability than those (BLsAP1 and BLsAP2) fromthe blocky-fruited cultivar.
RESUMO
A qualitative and quantitative comparison of the ultrastructure of the hepato-cyte lysosomes of adult monkeys, dogs, cats, rabbits, rats, and mice were carried out.The dense bodies in the hepatocytes in the animals studied were similar in their ultrastructure but different in their number and size. The digestive vacuole was more numerous in rats, mice, rabbits and monkeys than in dogs and cats. But the residue body was scarcely found in rats, mice and rabbits, a little more in cats and monkeys, and quite a lot in dogs. Besides, some undigested globular substances were found just entering into the residue bodies to be digested. The difference of the digestive vacuoles and residue bodies in the hepatocytes of these mammals are probably due to the species difference and the different kinds of food eaten.In dogs and monkeys, bristle coated vesicles were formed by the budding out of the adjacent cell membrane of two hepatocytes with one end of the budding in-vaginating into the cytoplasm and the other end enlarged and pinching out.The results of morphometric analysis of lysosomes of the hepatocytes were different in the 6 kinds of mammals studied.The volume density of lysosomes of the hepatocytes was the highest in dogs and the lowest in mice, and the numerical density was the highest in monkeys and the lowest in rabbits.