Effect of stress during handling, seawater acclimation, confinement, and induced spawning on plasma ion levels and somatolactin immunoreactivity in mature female thin -lipped gray mullet, Liza ramada

Understanding the physiological picture of fish during the reproductive cycle, seawater acclimation, and induced spawning is of essential value to know the possible reasons of preoviposition mortality and to develop successful hatchery technology. Determination of the effect of different stress factors on hydro-mineral balance as well as changes in somatolactin [SL] immunoreactive cells in mature Liza ramada females. Water chemistry and the different plasma ion levels were measured. Immunocytochemical staining for the sections of the pituitary gland was performed to describe the activity of SL immunoreactive cells. The plasma levels of PO[3-4], Na[+], K[+], Ca[2+], and Mg[2+] showed a slight increase during transportation without anesthesia. The concentrations of these minerals returned to the initial levels by using clove oil [5 mg/I] as anesthetic. However, their levels decreased during seawater acclimation and gradually increased with confinement to reach the initial values. Furthermore, the levels of PO[3-4], Na[+], K[+], Ca[2+], and Mg[2+] were significantly [P

Functional change of dextran-modified alpha-amylase from bacillus acidocaldarius

ALPHA-AMYLASE from Bacillus acidocaldarius was modified by covalent coupling to activated dextran with retained activity of 77.7%. After conjugation, the enzyme was stable within a broader pH range than the native enzyme and its optimum temperature increased by 10°C compared to the native enzyme. The conjugated a amylase exhibited a higher K[m] [Michaelis constant], lower V[max] [maximal reaction rate] and lower E[A] [activation energy] than the native enzyme. Covalent attachment of alpha- amylase to activated dextran protected the enzyme against heat inactivation. In the presence of the substrate, the conjugated enzyme retained 68.2% of its original activity after incubation at 70°C for 30 min which was more than that retained by the native enzyme [50.3%] under the same conditions. The calculated t[1/2] [half-life time] values of heat inactivation energy at 50, 60°C were 89 and 56 mm, respectively for the conjugated enzyme, whereas at these temperatures the native enzyme was less stable [t[1/2] 60 and 47 min, respectively]. The deactivation rate constant at 80°C for the conjugated a-amylase is about 11.9x10[-3]/ min, which is lower than that of the native enzyme [14.8x10[-3]/ min]. Conjugated a-amylase was more stable against chemical denaturation than the native enzyme, and retained 70.6% of its activity in presence of CuSO[4] [10 mM] while the native form of retained only 34.1%

Production of ethanol by yeasts grown on hydrolysate of Egyptian sweet potato

The influence of different concentrations of HCl for acid hydrolysis of Egyptian sweet potato for maximal ethanol yield was studied. The optimum HCl concentration was 0.5 N with respect to reducing sugars formed [60% DE] and minimum hydroxymethyl furfural content [0.05%] at 97C for 20 minutes. Total solids for Egyptian sweet potato was 27%, reducing sugars and glucose content based on fresh weight were 27.53%, 26.7%, respectively. Both hydrolyzed sweet potato slurry [SPS] and glucose [at concentration 4.5%] were subjected to fermentation by 4 different yeast strains for 4 days of growth. The results showed optimum ethanol yield after 72 hours of fermentation with respect to Saccharomyces cerevisiae, Saccharomyces uvarum yielding 0.3 g/g, 0.31 g/g, respectively. Upon using Pachysolen tannophilus, the maximum ethanol yield was obtained after the first 24 hours 0.24% g/g and Pichia pinus was 0.27 g/g after 48% hours of fermentation. The yields of yeast cells were estimated after 96 hours of fermentation and indicated the presence of high dry weight of cells [4.0-8.5 g/L] with considerable amounts of crude protein [35-45%] and true protein [20.3-27.4%]