Nanomaterials are being applied due to their excellent characteristics, such as the high surface area-to-volume ratio, excellent physicochemical properties, and biological compatibility. Chitosan is an amino polysaccharide and a versatile, second-most abundant natural polymer. In this presented work, chitosan was purified from Penaeus vannamei from the Persian Gulf and the homogeneity level was used a combination of three procedures: deproteinization, demineralization, and deacetylation. Chitosan nanoparticles were synthesized by the ionization gelation technique. P. vannamei protease immobilized on the surface of the positively charged chitosan nanoparticles through ionic or electrostatic interaction. The immobilized enzyme exhibited better tolerance to variations in the medium pH and temperature, enhanced pH and temperature stability, improved storage stability, and good reusability compared with the free enzyme. The Michaelis-Menten kinetic constant (K m), the maximum reaction velocity (V max), and the catalytic efficiency (k cat) for native P. vannamei protease were 2.5 µM, 87 µM. min −1 , and 132 min −1 , respectively, whereas for immobilized enzyme, K m , V max , and k cat values were 2.7 µM, 83 µM. min −1 , and 128 min −1 , respectively. The effect of both soluble and immobilized P. vannamei protease on the clarification of orange juice was also analysed.

In a study of the age and growth of Platycephalus indicus, a total of 1106 fish were collected from May 2011 to March 2012 in the coastal waters of Iran, Persian Gulf. The ages of 279 specimens were determined by sectioned otoliths. The ages of the females were estimated to be between 0+ to 7+ , while the ages of the males were from 0+ to 4+. The von Bertalanffy growth curve was well suited to the age/total length data of males and females as follows: Lt = 43.40{1–exp[−0.45(t + 0.328)]} for males, and Lt = 63 {1–exp[−0.50(t + 0.30)]} for females. linf = 43.40, k = 0.45, t0 = −0.328 for females and linf = 63, k = 0.50, t0 = −0.30 for males. The estimated values of natural mortality (M) were M = 0.886 yr−1 for females and 0.736 yr−1 for males, and the estimated Z values were 1.43 yr−1 for females and 1.62 yr−1 for males. The mean value of the gonadosomatic index for males and females was 0.82 ± 0.25 and 2.48 ± 0.59, respectively, in each year. The mean values of the hepatosomatic index (HSI) were 0.89 ± 0.20 for males and 1.28 ± 0.16 for females. The highest HSI values for this location were observed in January, and the lowest were in April.

No abstract

No abstract

No abstract

No abstract