Humberto Villarreal-Colmenares

Yolk proteins during ovary and egg development of mature female freshwater crayfish (Cherax quadricarinatus).

Vitellins from ovaries and eggs at different stages of development in freshwater crayfish (Cherax quadricarinatus) were examined by chromatography, PAGE and SDS-PAGE. With these methods, two forms of vitellin (Vt1 and Vt2) were observed in ovaries and eggs (stages I and V). In ovaries in secondary vitellogenesis, native molecular mass was 470 (Vt1) and 440 (Vt2) kDa. The electrophoretic pattern of the eggs proved to be more complex. The protein molecular mass depend on the development stage of the egg: stage I, 650 kDa (Vt1) and 440 kDa (Vt2); stage V, 390 kDa (Vt1) and 340 kDa (Vt2). The identified vitellins appear to be lipo-glycocarotenoprotein. A similar vitellin polypeptide composition was observed in the two forms of vitellin from ovaries and eggs in stage V. In ovaries the SDS-PAGE analysis showed four subunits with molecular weights of approximately 180, 120, 95 and 80 kDa (Vt1 and Vt2). The polypeptide composition in the two forms of vitellins in stage I and stage III eggs were different at 195, 190, 130 and 110 kDa (Vt1) and 116 and 107 kDa (Vt2). On the other hand, in stage V eggs, 110, 95, 87 and 75 kDa (Vt1 and Vt2) were identified. Two antibodies (Ab1 and Ab2) were prepared against the purified proteins of stage V eggs and their specificity was demonstrated by radial immunoprecipitation, and Western blotting analysis. Two forms of vitellins were also found in stage V eggs after chromatography on Sepharose CL-2B column and hydroxylapatite and polyacrylamide gel electrophoresis.

Effect of aeration rate on growth, survival and yield of white shrimp Penaeus vannamei in low water exchange ponds

A study was conducted in Bahia Kino, Sonora, northwest Mexico, to evaluate the effect of aeration rate on the growth, survival and yield of the white shrimp Penaeus vannamei farmed in ponds with reduced water exchange. Aeration rates of 0, 6, 12 and 24 h per day were tested. No significant differences in growth rate were detected among treatments. Survival and yield were significantly higher in ponds with 12 and 24 h of aeration.

TEMA: A software reference to shrimp Litopenaeus vannamei farming practices

Abstract A user‐friendly expert system (TEMA) was developed as a generic reference relating to TEechnological and MAnagement aspects of shrimp Litopenaeus vannamei farming practices. The software provides assistance to confirm, complement or modify the information that users of the expert system have of semi‐intensive and intensive technologies for grow‐out, and management practices for controlling pond water quality, productivity and feeding. Nursery techniques are also considered. Domain knowledge was represented using 433 rules, which constitute the knowledge base of the expert system. Hypertext protocol was employed to present information menus which include the justification of recommendations and conclusions, references from the literature, useful information regarding the specific topic analysed, support for data entry and on‐screen or printed final reports summarizing the consultation. Software facilities use 627 screens, 62 bibliographical references and 12 400 words in hypertext protocol, TEMA h...

Efecto de la adición del rotífero Brachionus rotundiformis (Tschugunoff, 1921) sobre la calidad del agua y la producción, en cultivos super-intensivos de camarón blanco del Pacífico Litopenaeus vannamei (Boone, 1931)

Se evaluo la efectividad del rotifero Brachionus rotundiformis como alimento natural exogeno combinado con alimento balanceado sobre los parametros de produccion de Litopenaeus vannamei y la calidad del agua. Se probaron diferentes concentraciones de rotiferos: 0, 5, 10, 15 y 20 rotiferos mL-1 durante 45 dias. No se encontraron diferencias en los niveles de fosfatos entre los tratamientos. El pH fue estadisticamente menor en los tratamientos con 15 y 20 rotiferos mL-1. Los nitratos, nitritos y amonio fueron significativamente menores en los tratamientos con baja concentracion de rotiferos (0 y 5 mL-1), mientras que los valores mas elevados se presentaron en las concentraciones mas altas (15 y 20 mL-1) sin que estas llegaran a ser toxicas. El peso ganado, biomasa, supervivencia y tasa de crecimiento especifico de L. vannamei fueron significativamente mayores en los tratamientos con mayor numero de rotiferos (15 y 20 mL-1), mientras que los valores mas bajos se encontraron en el tratamiento control (0 mL-1). El factor de conversion alimenticia (FCA) fue estadisticamente menor en el tratamiento con mayor concentracion de rotiferos, mientras que el factor de conversion alimenticia (FCA) mas alto se encontro en el tratamiento control. Se concluye que el uso del rotifero B. rotundiformis en altas concentraciones mejora los parametros de produccion del camaron blanco del Pacifico sin llegar a deteriorar de manera importante la calidad del agua