RESUMO
The occurrence of tiger shark Galeocerdo cuvier in the Atlantic Ocean was assessed using at-sea observer data from multiple pelagic longline fisheries. Geographic positions of 2764 G. cuvier recorded between 1992 and 2013 and covering a wide area of the Atlantic Ocean were compared with the currently accepted distribution ranges of the species. Most records fell outside those ranges in both the Southern and Northern Hemispheres, which strongly suggests that the distribution range of G. cuvier in the open ocean is considerably larger than previously described.
Assuntos
Tubarões/fisiologia , Algoritmos , Animais , Oceano Atlântico , Pesqueiros , Movimentos da ÁguaRESUMO
Reverse micelles (RMs) are very good nanoreactors because they can create a unique microenvironment for carrying out a variety of chemical and biochemical reactions. The aim of the present work is to determine the influence of different RM interfaces on the hydrolysis of 2-naphthyl acetate (2-NA) by alpha-chymotrypsin (alpha-CT). The reaction was studied in water/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/benzene RMs and, its efficiency compared with that observed in pure water and in sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) RMs. Thus, the hydrolysis rates of 2-NA catalyzed by alpha-CT were determined by spectroscopic measurements. In addition, the method used allows the joint evaluation of the substrate partition constant K(p) between the organic and the micellar pseudophase and the kinetic parameters: catalytic rate constant k(cat), and the Michaelis constant K(M) of the enzymatic reaction. The effect of the surfactant concentration on the kinetics parameters was determined at constant W(0)=[H(2)O]/[surfactant], and the variation of W(0) with surfactant constant concentration was investigated. The results show that the classical Michaelis-Menten mechanism is valid for alpha-CT in all of the RMs systems studied and that the reaction takes place at both RM interfaces. Moreover, the catalytic efficiency values k(cat)/K(M) obtained in the RMs systems are higher than that reported in water. Furthermore, there is a remarkable increase in alpha-CT efficiency in the cationic RMs in comparison with the anionic system, presumably due to the unique water properties found in these confined media. The results show that in cationic RMs the hydrogen-bond donor capacity of water is enhanced due to its interaction with the cationic interface. Hence, entrapped water can be converted into "super-water" for the enzymatic reaction studied in this work.