Efecto de la temperatura y salinidad en la eclosión y supervivencia de Aedes aegypti (L) (Diptera: Culicidae) procedentes del occidente de México / Effect of temperature and salinity on the eclosion and survival of Aedes aegypti (L) (Diptera: Culicidae) from Western Mexico

Introducción: Aedes aegypti (L) (Diptera: Culicidae), es una especie cosmopolita y vector de arbovirosis. Las variaciones de la temperatura y salinidad del agua influyen en la eclosión y supervivencia de fases larvales. Objetivo: Evaluar el efecto de diferentes temperaturas y salinidades en la eclosión de huevos y la supervivencia de larvas, pupas y adultos bajo condiciones de laboratorio. Métodos: Se colectaron larvas de Ae. aegypti, de reservorios artificiales en la zona periurbana de Puerto Vallarta, Jalisco, México, y se mantuvieron hasta la fase adulta. Los huevos obtenidos se sometieron a ocho temperaturas (15, 17, 20, 25, 27, 30, 32 y 35 °C). Se colocaron 15 huevos por quintuplicado y se evaluó la eclosión durante 96 h. Se colocaron 100 huevos con agua ajustada a 0.3, 2, 5, 10, 15,18 y 22 ups y se evaluó la eclosión hasta las 96 h. Adicionalmente se utilizaron larvas del estadio IV, por quintuplicado, sometiéndose a las mismas salinidades y se evaluó la supervivencia hasta las 48 h. El efecto de la salinidad en la ovoposición de las hembras se llevó a cabo introduciendo recipientes con las mismas concentraciones salinas, dentro en las jaulas entomológicas. Resultados: Se registró el 100 por ciento de eclosión a las 24 y 48 h; la temperatura de 35° C no registró eclosión. Las salinidades de 22 y 18 ups, provocaron mortalidad del 100 por ciento a las 24 h. En la salinidad de 15 ups, sobrevivió el 50 por ciento. Las concentraciones de 2, 5 y 10 ups demostraron 100 por ciento de supervivencia hasta la fase de adulto. La supervivencia de larvas del estadio IV en los tratamientos 2, 5 y 10 fue del 100 por ciento y en 15,18 y 22 ups disminuyó a 50, 80 y 100 por ciento, respectivamente (p˂ 0,05). Las diferentes concentraciones salinas no afectaron significativamente la ovoposición. La eclosión solo se presentó en las concentraciones de 0,3; 2; 5 y 10 ups. Los huevos ovopositados en concentraciones de 15, 18 y 22 ups no eclosionaron hasta que fueron transferidos a agua dulce con porcentajes de eclosión de entre el 80 y 90 por ciento. Conclusiones: Los embriones de Ae. aegypti poseen una amplia plasticidad para soportar cambios drásticos de temperatura y salinidad. El control efectivo de sus poblaciones debe incluir la revisión de charcas o reservorios que contengan aguas salobres hasta 18 ups(AU)

Introduction: Aedes aegypti (L) (Diptera: Culicidae) is a cosmopolitan species and a vector of arboviruses. Variations in the temperature and salinity of the water affect eclosion and survival during the larval stages. Objective: Evaluate the effect of different temperatures and salinities on the eclosion of eggs and the survival of larvae, pupae and adults in laboratory conditions. Methods: Ae. aegypti larvae were collected from artificial reservoirs in a peri-urban area of Puerto Vallarta, Jalisco, Mexico, and maintained until the adult stage. The eggs obtained were subjected to eight temperatures (15, 17, 20, 25, 27, 30, 32 and 35 °C). Fifteen eggs were placed in quintuplicate and eclosion was evaluated for 96 h. One hundred eggs were placed with water adjusted to 0.3, 2, 5, 10, 15, 18 and 22 psu and eclosion was evaluated until 96 h. Additionally, stage IV larvae were used in quintuplicate, subjecting them to the same salinities and evaluating survival until 48 h. The effect of salinity on oviposition by females was determined by introducing containers with the same salinity into the entomological cages. Results: 100 percent eclosion was recorded at 24 and 48 h, whereas no eclosion occurred at a temperature of 35 °C. Salinities of 22 and 18 psu caused 100 percent mortality at 24 h, whereas 50 percent survived at a salinity of 15 psu. At concentrations of 2, 5 and 10 psu 100 percent of the larvae survived until the adult stage. Survival of stage IV larvae in treatments 2, 5 and 10 was 100%, whereas in 15, 18 and 22 psu it fell to 50, 80 and 100 percent, respectively (p˂ 0.05). The different salinities did not affect oviposition significantly. Eclosion only occurred at concentrations of 0.3, 2, 5 and 10 psu. Oviposited eggs at concentrations of 15, 18 and 22 psu did not eclose until they were transferred to fresh water, where eclosion percentages ranged between 80 percent and 90 percent. Conclusions: Ae. aegypti embryos have great plasticity to endure drastic changes in temperature and salinity. Effective control of their populations should include inspection of ponds and reservoirs containing brackish water of up to 18 psu(AU)

Screening and Immobilization of Interfacial Esterases from Marine Invertebrates as Promising Biocatalyst Derivatives.

Interfacial esterases are useful enzymes in bioconversion and racemic mixture resolution processes. Marine invertebrates are few explored potential sources of these proteins. In this work, aqueous extracts of 41 species of marine invertebrates were screened for esterase, lipase, and phospholipase A activities, being all positive. Five extracts (Stichodactyla helianthus, Condylactis gigantea, Stylocheilus longicauda, Zoanthus pulchellus, and Plexaura homomalla) were selected for their activity values and immobilized on Octyl-Sepharose CL 4B support by interfacial adsorption. The selectivity of this immobilization method for interfacial esterases was evidenced by immobilization percentages ≥ 94% in almost all cases for lipase and phospholipase A activities. Six pharmaceutical-relevant esters (phenylethyl butyrate, ethyl-2-hydroxy-4-phenyl-butanoate, 2-oxyranylmethyl acetate (glycidol acetate), 7-aminocephalosporanic acid, methyl-prostaglandin F2α, and methyl-6-metoxy-α-methyl-2-naphtalen-acetate -naproxen methyl ester-) were bioconverted by at least three of these biocatalysts, with the lowest conversion percentage of 24%. In addition, three biocatalysts were used in the racemic mixture resolution of three previous compounds. The S. helianthus-derived biocatalyst showed the highest enantiomeric ratios for glycidol acetate (2.67, (S)-selective) and naproxen methyl ester (8.32, (R)-selective), and the immobilized extract of S. longicauda was the most resolutive toward the ethyl-2-hydroxy-4-phenyl-butanoate (8.13, (S)-selective). These results indicate the relevance of such marine interfacial esterases as immobilized biocatalysts for the pharmaceutical industry.

Evaluación del efecto tóxico de hongos Basidiomycota en la eclosión de quistes de Artemia franciscana / Evaluation of the toxicity of Basidiomycota fungi on the hatching of Artemia franciscana cysts

Antecedentes. El consumo de hongos silvestres se ha incrementado en los últimos años; sin embargo, no todos son comestibles y algunos son causantes de varios tipos de envenenamiento. Por esto es necesario realizar estudios que aporten información de su toxicidad. Artemia franciscana es un crustáceo que se emplea en ensayos de toxicidad con una gran aplicación en la detección de toxinas fúngicas. Objetivos. Determinar el porcentaje de inhibición de la eclosión y mortalidad de quistes de A. franciscana producidos por extractos de hongos de la división Basidiomycota. Métodos. Se prepararon extractos acuosos de basidiomas de 15 especies de basidiomicetos recolectados en Jalisco (México) y se probó el efecto de diferentes concentraciones sobre quistes de A. franciscana. Se utilizaron dicromato de potasio y agua de mar como controles positivo y negativo, respectivamente. Se determinaron los porcentajes de inhibición de la eclosión y de la mortalidad de los quistes de A. franciscana. Resultados. Trece de las 15 especies estudiadas afectaron en más del 80% la eclosión de los quistes de A. franciscana en todas las concentraciones probadas; en contraste, el dicromato de potasio inhibió la eclosión en menos del 50%. El mayor porcentaje de mortalidad en los quistes fue causado por los extractos acuosos de Amanita virosa, Leucopaxillus amarus y Tylopilus violatinctus, y el menor lo produjo el extracto de Macrolepiota mastoidea. Conclusiones. El ensayo con A. franciscana demostró ser eficaz en la evaluación de la toxicidad de los hongos, con la excepción de Scleroderma texense, que se considera venenoso, y que no resultó tóxico para este crustáceo (AU)

Background. The consumption of wild mushrooms has increased in recent years. However, not all mushrooms are edible and some of them may cause poisoning. Therefore, their toxicity needs to be studied. Artemia franciscana is a crustacean used in toxicity tests including toxins of fungi. Aims. To determine the percentage of inhibition and mortality produced by extracts of several basidiomycetes on the hatching of A. franciscana cysts. Methods. Aqueous extracts were prepared from 15 species of mushrooms collected from Jalisco state, Mexico. Different concentrations of the extracts were assayed in order to test their toxicity. Potassium dichromate and artificial seawater were the positive and negative controls, respectively. The percentages of hatching and mortality of the cysts were evaluated. Results. Inhibition of hatching greater than 80% in all the concentrations tested was found in 13 of the 15 species studied, in contrast to the positive control, which inhibited cyst hatching less than 50% in all cases. The highest percentage of mortality in the cysts was caused by the aqueous extracts of Amanita virosa, Leucopaxillus amarus, and Tylopilus violatinctus, and the lowest by Macrolepiota mastoidea. Conclusions. The brine shrimp bioassay appeared to be useful in the evaluation of the toxicity of several basidiomycetes, with the exception of Scleroderma texense, a mushroom considered poisonous, which showed no toxicity over A. franciscana (AU)

[Evaluation of the toxicity of Basidiomycota fungi on the hatching of Artemia franciscana cysts]. / Evaluación del efecto tóxico de hongos Basidiomycota en la eclosión de quistes de Artemia franciscana.

BACKGROUND: The consumption of wild mushrooms has increased in recent years. However, not all mushrooms are edible and some of them may cause poisoning. Therefore, their toxicity needs to be studied. Artemia franciscana is a crustacean used in toxicity tests including toxins of fungi. AIMS: To determine the percentage of inhibition and mortality produced by extracts of several basidiomycetes on the hatching of A. franciscana cysts. METHODS: Aqueous extracts were prepared from 15 species of mushrooms collected from Jalisco state, Mexico. Different concentrations of the extracts were assayed in order to test their toxicity. Potassium dichromate and artificial seawater were the positive and negative controls, respectively. The percentages of hatching and mortality of the cysts were evaluated. RESULTS: Inhibition of hatching greater than 80% in all the concentrations tested was found in 13 of the 15 species studied, in contrast to the positive control, which inhibited cyst hatching less than 50% in all cases. The highest percentage of mortality in the cysts was caused by the aqueous extracts of Amanita virosa, Leucopaxillus amarus, and Tylopilus violatinctus, and the lowest by Macrolepiota mastoidea. CONCLUSIONS: The brine shrimp bioassay appeared to be useful in the evaluation of the toxicity of several basidiomycetes, with the exception of Scleroderma texense, a mushroom considered poisonous, which showed no toxicity over A. franciscana.

Control químico y biológico de larvas de Aedes aegypti en la costa norte de Jalisco, México / Chemical and biological control on Aedes aegypti larvae in the northern coastal region of Jalisco, Mexico

Introducción: el aumento de enfermedades transmitidas por mosquitos se ha asociado a cambios globales: el crecimiento de la población, la urbanización y el cambio climático. Dentro de las alternativas para evitar epidemias están el control químico y biológico. Objetivos: determinar las concentraciones efectivas de tres compuestos químicos para el control de larvas de Aedes aegypti en la región costa norte de Jalisco, México, y evaluar la capacidad predatoria de diversas especies acuáticas sobre larvas de mosquitos. Métodos: se evaluaron cinco concentraciones de temefos (1,5; 1; 0,1; 0,05 y 0,01 g/L), hipoclorito de sodio (5,5; 0,55; 0,05; 0,005 y 0,0005 g/L) y detergente (10; 5; 1; 0,5; 0,1 g/L). Se determinó la muerte de las larvas a 1, 3, 6 y 24 h y se calculó la CL50. Se evaluaron cuatro especies de peces, un crustáceo y una larva de díptero culícido. Se les suministraron diferentes cantidades de larvas (5, 10, 30, 50 y 80) por quintuplicado y se registró su consumo a diferentes tiempos (1, 3, 5, 9 y 24 h). Resultados: el temefos provocó el 100 por ciento de mortalidad en todas las concentraciones probadas. El NaClO provocó mortalidad del 100 por ciento en las dos concentraciones más altas. El detergente fue más eficiente a las tres concentraciones mayores. Los peces demostraron un consumo de casi el 100 por ciento en la mayoría de las densidades probadas. La larva de díptero culícido demostró un consumo cercano al 80 por ciento, el crustáceo solo consumió el 53 por ciento Conclusiones: el uso del temefos debe continuar siendo el larvicida químico de elección en Puerto Vallarta, México. La utilización de peces nativos se sugiere como adecuada para el control biológico(AU)

Introduction: the increase of diseases transmitted by mosquitoes has been associated to global changes such as the population growth, urbanization and climate change. Among the alternatives to avoid epidemics are the chemical and biological control. Objectives: to determine effective concentrations of three chemical compounds to control Aedes aegypti larvae in the northern coastal region of Jalisco and to evaluate the predatory ability of various aquatic species on mosquito larvae. Methods: five concentrations of temephos of (1.5, 1, 0.1; 0.05 and 0.01 g/L), sodium hypochlorite (5.5, 0.55, 0.05, 0,005 and 0.0005 g/L) and detergent (10, 5, 1, 0.5, 0.1 g/L) were evaluated. Larval death was estimated at different times (1, 3, 5, 9 and 24 h) and the LC50 was calculated. Four fish species, one crustacean and one dipteral culicid larva were evaluated. All were provided with different numbers of larvae (5, 10, 30, 50 and 80) five times and the larval consumption was recorded at different times (1, 3, 5, 9 and 24 h). Results: temephos caused 100 percent mortality of larvae in all tested concentrations. The NaClO caused 100 percent mortality at the two highest concentrations. The detergent was more efficient at the three higher concentrations. Fish proved to be efficient predators of larvae, as they consumed almost 100 percent of larvae in most of tested densities. The diptera culicid larva reached around 80 percent consumption whereas crustacean consumed only 53 percent. Conclusions: the use of temephos should remain the chemical larvicide of choice in Puerto Vallarta region. Native fish are suggested to be used as appropriate biological control agents(AU)

Evaluación de la toxicidad de Psilocybe cubensis (Agaricales, Basidiomycota) sobre Artemia franciscana (Crustacea, Anostraca) / Evaluation of Psilocybe cubensis (Agaricales, Basidiomycota) toxicity over Artemia franciscana (Crustacea, Anostraca)

Antecedentes. Psilocybe cubensis es una especie de acción psicodisléptica, que crece sobre estiércol vacuno en praderas de zonas tropicales y subtropicales, consumido en México desde épocas ancestrales tanto con fines ceremoniales y rituales como curativos o medicinales. Artemia franciscana es un crustáceo utilizado con frecuencia como organismo modelo para pruebas de toxicidad. Objetivos. Conocer la toxicidad de P. cubensis, a través de un extracto de esta especie, sobre nauplios y adultos de A. franciscana. Métodos. Los especímenes se recolectaron en la región de Bahía de Banderas, Jalisco, México, se secaron y homogeneizaron en agua de mar artificial. Los bioensayos se realizaron en tubos de ensayo con diferentes concentraciones del extracto de P. cubensis (EAP) y con dicromato de potasio como sustancia tóxica de referencia. Para conocer la toxicidad se calculó la concentración letal media (CL50) en nauplios y adultos y el porcentaje de inhibición de la eclosión de los quistes de A. franciscana. Resultados. Los nauplios presentaron una CL50=135mg/ml, mientras que la de los adultos fue CL50=172mg/ml. El EAP inhibió la eclosión de los quistes en un 100% en todas las concentraciones. Conclusiones. Bajo las condiciones de este estudio, el extracto de P. cubensis resultó tóxico para nauplios y adultos de A. franciscana(AU)

Background. Psilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing. Aims. With the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented. Methods. Specimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC50) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated. Results. Nauplii showed a LC50=135mg/ml, while adults a LC50=172mg/ml. Cysts’ hatching was inhibited by the EAP at all tested concentrations. Conclusions. Under the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana(AU)

[Evaluation of Psilocybe cubensis (Agaricales, Basidiomycota) toxicity over Artemia franciscana (Crustacea, Anostraca)]. / Evaluación de la toxicidad de Psilocybe cubensis (Agaricales, Basidiomycota) sobre Artemia franciscana (Crustacea, Anostraca).

BACKGROUND: Psilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing. AIMS: With the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented. METHODS: Specimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC(50)) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated. RESULTS: Nauplii showed a LC(50) = 135 µg/ml, while adults a LC(50) = 172 µg/ml. Cysts' hatching was inhibited by the EAP at all tested concentrations. CONCLUSIONS: Under the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana.

Efecto del nivel proteico de la dieta sobre el desarrollo de juveniles de Macrobrachium tenellum (Smith, 1871) / Effect of dietary protein level on the development of juveniles of Macrobrachium tenellum (Smith, 1871)

Objetivo.Evaluar el efecto de cinco niveles de proteína cruda (PC) en alimentos balanceados sobre el crecimiento, sobrevivencia y tasa de conversión alimenticia (FCA) en juveniles de Macrobrachium tenellum. Materiales y métodos. Se alimentó por 60 días a juveniles de M. tenellum (0.31±0.01 g y 32.62±1.10 mm) con niveles de 20, 25, 30, 35 y 40% de PC en el alimento. Los organismos fueron distribuidos al azar en 15 tinas experimentales de 64 L (15 org./tina) bajo condiciones controladas (5.95±0.41 ppm de oxígeno, 29.89±0.72°C, y pH 8.44±0.15) y alimentados con el 10% de su peso vivo. Resultados. El porcentaje de sobrevivencia fue del 98.22±3.96% sin diferencias significativas entre los tratamientos (p>0.05). Los organismos alimentados con un 40% de PC tuvieron un peso significativamente mayor (p<0.05) respecto a los demás tratamientos (cambio de peso de 0.54±0.02g; incremento de peso de 173.60±12.99%; y tasa de crecimiento específico de 1.68±0.08). El FCA fue significativamente mejor (p<0.05) en los organismos alimentados con 35 y 40% de PC (2.85±0.18 y 2.40±0.05, respectivamente) que los demás tratamientos. Conclusiones. Los organismos juveniles de M. tenellum alimentados con niveles altos de proteína (40%), se desarrollaron más rápido que organismos que recibieron una menor concentración de proteína bajo las condiciones experimentales establecidas en este estudio.

Objective. To evaluate the effect of five levels of crude protein (CP) in balanced feed on the survival, growth and feed conversion ratio (FCA) in juveniles of Macrobrachium tenellum. Materials and methods. Juveniles of M. tenellum (0.31±0.01g and 32.62±1.10mm) were fed for 60 days with 20, 25, 30, 35 and 40% of CP in feed. The organisms were randomly distributed in 15 experimental tanks (15 org /tank) under controlled conditions (5.95±0.41 ppm of oxygen, 29.89 ± 0.72 °C, and pH 8.44±0.15) and fed with 10% of its live weight. Results. The survival percentage was 98.22±3.96% with no statistical difference between treatments (p>0.05). The organisms fed with 40% CP in their diet had a significantly higher weight (p<0.05) compared to the other treatments (weight change of 0.54±0.02g; weight increase 173.60±12.99%, and specific growth rate of 1.68±0.08). The FCA was significantly better (p<0.05) in organisms fed with 35 and 40% CP (2.85±0.18 and 2.40±0.05, respectively) than other treatments. Conclusions. Juveniles of M. tenellum fed with high protein levels (40%) developed faster than organisms which received a lower concentration of the protein under the experimental conditions established for this study.

[Predatory capacity of Macrobrachium tenellum on Aedes aegypti larvae in lab conditions]. / Capacidad depredadora del langostino Macrobrachium tenellum sobre larvas de Aedes aegypti en condiciones de laboratorio.

INTRODUCTION: in the last few years, a lot of importance has been given to natural predators against Aedes aegypti. Several organisms have been studied both in lab and in the field so as to find out their capacity to devour mosquito larvae. High densities of Macrobrachium tenellum are found in natural conditions, it is not aggressive and may stand wide ranges of temperature, rates of salinity and oxygen concentrations. OBJECTIVE: to evaluate the predatory capacity of Macrobrachium tenellum on Aedes aegypti larvae in lab conditions. METHODS: very young Macrobrachium tenellum prawns measuring A(3.0-3.5cm) and B (4.5-5 cm) were used. The mosquito larvae were obtained after hatching of egss from adult females kept in entomological cages. Five, ten, fifteen and twenty Aedes aegypti larvae were placed per treatment per rank, whereas the second bioassays adjusted the number of larvae to 30, 40, 50 and 80 larvae per treatment per rank. RESULTS: Macrobrachium tenellum showed high rate of larval consumption for the two ranks and treatments. In the highest density (80 larvae), the consumption was 95% of larvae at 24 hours for rank A and 100% for rank B. CONCLUSIONS: Macrobrachium tenellum may be considered as a potential biological control agent, due to its abundant presence in natural conditions, its resistance to different environmental conditions and to its voraciousness seen in this study.

Partial characterization of pyloric-duodenal lipase of gilthead seabream (Sparus aurata).

In the present study, we report the isolation and characterization of seabream Sparus aurata pyloric caeca-duodenal lipase. Optimum activity was found at pH 8.5 and salinity of 50 mM NaCl. Lipase activity was sensitive to divalent ions, and extreme pH values (4, 5, and 12), being more stable at alkaline than acid pH. Optimum temperature was found at 50°C, but lipase was stable at temperatures below 40°C. Lipase has a bile salt sodium taurocholate requirement for increased activity. Gradient PAGE electrophoresis revealed the presence of four isoforms with apparent molecular masses of 34, 50, 68, and 84 KDa, respectively. Pyloric-duodenal lipase was able to hydrolyze emulsified alimentary oils. Results confirm the presence of true lipases in Sparus aurata digestive tract.

Extraction systems for isolating esterases having interfacial adsorption / Sistemas de extracción para el aislamiento de esterasas con adsorción interfacial

En el presente trabajo se optimizaron las condiciones de extracción de esterasas con actividad en interfaces, a partir de la anémona marina Stichodactyla helianthus y del camarón peneido Litopenaeus vannamei Las esterasas interfaciales, cuya presencia en estas especies había sido informada previamente, presentan características funcionales que las hacen muy atractivas para su empleo industrial. Los homogenados de los animales se trataron con los detergentes Tritón X-100, Tween 20 y Tween 80 en dos concentraciones cada uno: la Concentración Micelar Crítica (CMC) y la mitad de ésta. Además se empleó NaCl 0,5 mol/L y n-butanol a las proporciones 5, 10 y 20%. Cada variante fue comparada con el método tradicional de extracción con agua destilada, que fue tomado como control. Los mejores resultados se obtuvieron empleando n-butanol al 20%, para recuperar las actividades esterasa y fosfolipasa, y al 10%, en el aislamiento de la actividad lipasa. La efectividad de este solvente en el aislamiento de estas enzimas con afinidad por las interfaces lípido/agua, pudiera estar dada por su capacidad para romper los agregados entre estas moléculas y causar la desorción de las mismas a los restos de membrana y tejidos presentes en la preparación.

Interfacial esterases present great functional versatility, making them very attractive molecules for industrial applications. The conditions for extracting interfacial esterases previously detected in the sea anemone Stichodactyla helianthus and the shrimp Litopenaeus vannamei were optimised in this work. Animal homogenates were treated with Triton X-100, Tween 20 and Tween 80 detergents at two different concentrations: critical micellar concentration (CMC) and half of that concentration; 0.5 mol/L NaCl and n-butanol at 5%, 10% and 20% v/v ratios were also tested. Each procedure was compared to the control extraction method using distilled water. The best results were obtained with 20% n-butanol for recovering esterase and phospholipase activity whilst 10% n-butanol extraction was the most effective for lipase activity isolation. This solvent’s suitability for isolating interface-activated enzymes could be explained by its ability to dissociate biomolecule aggregates and cause enzyme desorption from the membranes and tissues remaining in the preparation.

Characterization of digestive gland esterase-lipase activity of juvenile redclaw crayfish Cherax quadricarinatus.

Investigation of esterase-lipase activity in the digestive gland of redclaw crayfish Cherax quadricarinatus showed that the optimum enzyme activity occurred between 35 and 40 degrees C, with 100 mM NaCl at pH 8.5. Heavy metals completely inhibited and calcium ions partially inhibited enzyme activity. The enzyme activity diminished as the length of the fatty acid chain of substrates increased. Molecular masses for four isozymes were 43, 46, 63 and 118 kDa, respectively, as determined by PAGE.