Influence of feeding on the circadian rhythm of digestive enzymes in cultivated juveniles of the freshwater crayfish Cherax quadricarinatus (Parastacidae)

Se analiza en juveniles en etapa de engorde (7 g) de Cherax quadricarinatus, el ritmo circadiano de los niveles de proteínas totales, la actividad de las proteasas, lipasas y amilasas, y su posible modificación en función del momento de alimentación matutino (8 h) y vespertino (17 h). En general, la actividad de las enzimas digestivas de los juveniles de C. quadricarinatus no mostró un patrón circadiano de secreción, a excepción de las lipasas, donde se observó un incremento de actividad hacia la tarde-noche y disminución hacia las primeras horas de la mañana. Los niveles de proteína total, la actividad de proteinasas y amilasas registradas en la glándula digestiva, permanecieron prácticamente inalterados en todos los experimentos. A pesar de ello, se observó tendencia a que los niveles de actividad de proteinasas disminuyan luego del pulso de alimentación, recuperando los niveles anteriores 3 h después, independientemente del horario de alimentación. En cambio la actividad de amilasa no mostró ninguna tendencia por efecto del horario de alimentación. El estudio de los patrones de secreción de las enzimas digestivas y sus posibles modificaciones, podría ser utilizado como una herramienta para establecer los momentos del día más propicios para la alimentación de los juveniles en cultivo.ABSTRACT. We analyze in juvenile Cherax quadricarinatus fattening stage, the circadian rhythm of total protein levels, activity of proteases, lipases and amylases, and their possible change as a function of morning (8 h) and evening (17 h) feeding. In general, the activity of digestive enzymes of juvenile C. quadricarinatus showed no circadian pattern of secretion of lipases except where there was an increase towards the evening-night and a decrease towards the early hours of the morning. The total protein levels, the activity of proteinases and amylases of juveniles of C. quadricarinatus registered in the midgut gland remained virtually unchanged in all experiments. However, a non-significant tendency to diminish the proteinase activity levels after the feeding pulse was observed, with a return to previous enzymatic levels after 3 h. In contrast, the amylase activity did not show an observable effect by the feeding schedule. The study of the patterns of the digestive enzyme secretion and their possible changes, could be used as a tool to establish the most favorable times of the day for juveniles feeding.Fil: Sacristán, Hernán Javier. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina; Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina;Fil: Franco-Tadic, Luis M.. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Fisiologia de Crustáceos; Argentina;Fil: Lopez, Laura Susana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina; Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina

Surface modification of PVC membranes using fluorothiophenol compounds

The controlled chemical surface modification of PVC films by means of three fluoride aromatic compounds, 4-fluoro thiophenol, 3,4-difluorothiophenol and penta fluorothiophenol is reported. To obtain information about the surface selectivity of the reactions, the degree of modification of the polymer across the film was determined by depth profiling carried out using confocal Raman microscopy. It is shown that the gradient of the modification degree and the surface selectivity depend on the relationship between the rate constants of the substitution reaction and the diffusion process of the reactant. Therefore it is function of reaction time, temperature and the proportion of solvent/nonsolvent used for the reaction.Fil: Corrales, Marta. Instituto en Ciencia y Tecnología de Polímeros; EspañaFil: Bierbrauer, Karina Lilian. Instituto en Ciencia y Tecnología de Polímeros; España. Universidad de Córdoba; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Sacristán, Hernán Javier. Instituto en Ciencia y Tecnología de Polímeros; EspañaFil: Mijangos, Carmen. Instituto en Ciencia y Tecnología de Polímeros; Españ

Effects of starvation and stocking density on the physiology of the male of the southern king crab Lithodes santolla

The southern king crab (SKC)Lithodes santolla is an important commercial species in southern South America. There is a greater need for availability of fresh and live crabs during the season of highest demand in summer (mainly December and January). Thus, this study aimed to determine the effects of starvation and stocking densities on the physiological status of male SKC to know whether SKC can be stocked after they are fished. To assess the effects of starvation, crabs were assigned to two experimental groups: the Laboratory group (in which crabs were either fed daily (controls), fed every 15 days, or starved and the Sea group (in which crabs were either fed every 15 days or starved). Starved crabs showed a very slight mass reduction (<5%), glycogen depletion from the midgut gland (when kept at sea), lipid peroxidation reduction in both the muscle and the midgut gland, and micro-structural alterations of the midgut gland. Starved crabs were then analyzed at three stocking density levels: low (35 crabs m−3), medium (69 crabs m−3), and high (115 crabs m−3)for 30 days. In this experiment, we found, at all densities, a decreased weight of the midgut gland, a low condition index, decreased lipase activity, glycogen reduction, increased protein reserves, and lipid peroxidation reduction, and decreased lipid levels at low and medium densities. The muscle showed, at all densities, an increased protein oxidation and a decrease in the RNA:DNA ratio. Our results suggest that SKC can tolerate relatively high stocking densities, have low mortality, and are able to endure 60 days of food deprivation without lowering their flesh yield. This would allow marketing crabs alive off-season.Fil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Di Salvatore, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Fernandez Gimenez, Analia Veronica. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lovrich, Gustavo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Energy reserves mobilization: Strategies of three decapod species

In food deprivation assays, several different responses have been observed in crustaceans. However, studying energy reserves utilization among more than one species during the same starvation period has not yet been performed, particularly to discern whether the responses are due to intrinsic and/or environmental factors. We hypothesize that decapod species with similar feeding habits have the same strategies in the use of energetic reserves during starvation, even though they inhabit different environments. The aim of this study was to compare the energy reserves mobilization of three decapods species (Cherax quadricarinatus, Palaemon argentinus and Munida gregaria) with similar feeding habits, exposed to similar food deprivation conditions. The crayfish, shrimp and squat-lobster were experimentally kept at continuous feeding or continuous starvation throughout 15 days. Every 3rd day, the midgut gland index (MGI), and the glycogen, lipid and protein contents were measured in the midgut gland (MG) and pleon muscle. Palaemon argentinus mobilized more reserves during starvation, followed by C. quadricarinatus, and the last M. gregaria. The starved shrimps presented low MGI, whereas MG showed a reduction in glycogen (from day 6 to 15), lipid (from day 3 to 15), and protein levels (at day 9 and 15) while in their muscle, lipid reserves decreased at days 3 and 6. In C. quadricarinatus, the most affected parameters in the MG were MGI, glycogen (from day 6 to 15), and lipids (at day 12 and 15). In the MG of M. gregaria only the glycogen was reduced during fasting from 3 to 15 days. Even though the three studied species have similar feeding habitats, we found that their energetic profile utilization is different and it could be explained by the habitat, life span, temperature, organ/tissue, and metabolism of the species. Our results may be useful to understand the several different responses of crustaceans during starvation.Fil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Rodriguez, Yamila Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pereira, Nair de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Lovrich, Gustavo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Fernandez Gimenez, Analia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Evaluation of diets, feeding schedules, food availability, attractants and starvation period in juveniles of freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae). Breeding applications

La langosta de agua dulce, Cherax quadricarinatus, presenta numerosas características biológicas y comerciales que la convierten en una especie apropiada para la acuicultura. Sin embargo, el crecimiento productivo ha sido poco significativo en la Argentina debido a diferentes motivos tales como la ausencia de tecnologías de cultivo, elección inadecuada del sitio de cultivo y, principalmente, por la falta de ―semilla" en distintas fases para su comercialización. Dada la escasa información existente sobre el cultivo de esta especie, se plantearon los siguientes objetivos generales: evaluar y comparar los efectos de alimentos comerciales y formulados especialmente para esta especie sobre la fisiología digestiva; estudiar el ritmo diario de secreción de las enzimas digestivas y su posible modificación en función del momento de alimentación y el período de ayuno; evaluar la inclusión de la harina de calamar como atractante y analizar el efecto de la disponibilidad de alimento luego de un ayuno corto o moderado sobre la actividad de enzimas digestivas y estudiar el efecto del ayuno prolongado y posterior alimentación sobre las respuestas bioquímicas y fisiológicas de C. quadricarinatus. Los animales alimentados con el alimento especialmente formulado presentaron una buena condición fisiológica en función de la actividad enzimática digestiva y una estructura celular y tisular conservada de la glándula digestiva. Sin embargo, la dieta diseñada para esta especie presentó baja digestibilidad in vitro de proteínas. La secreción de las enzimas digestivas no mostró un patrón diario y el momento de alimentación (matutina o vespertina) afectó la actividad de las enzimas digestivas. El ayuno moderado provocó modificaciones en el patrón de ritmo diario de secreción de las enzimas digestivas. La harina de calamar no actuó como atractante para C. quadricarinatus, mientras que la disponibilidad de alimento luego de un período de ayuno corto no causó modificaciones en la actividad de las enzimas digestivas; por el contrario, dicha actividad se vio alterada por la disponibilidad de alimento cuando los animales fueron expuestos previamente a un ayuno prolongado. En función de los resultados obtenidos sobre la disponibilidad de alimento y a estudios previos de otros autores, se propone una posible vía de regulación de la actividad de la lipasa digestiva. Finalmente, el ayuno prolongado provocó la disminución de reservas energéticas (glucógeno y lípidos), niveles de glutatión reducido, actividad de lipasa y proteasa; y alteraciones en la estructura celular y tisular de la glándula digestiva, aunque no causó un incremento en el daño oxidativo. La posterior alimentación, luego del ayuno prolongado, provocó que se restablecieran todos los parámetros anteriormente descriptos. La presente tesis aporta información novedosa e importante sobre la respuesta fisiológica de la langosta de agua dulce C. quadricarinatus que podría ser de gran utilidad para el cultivo de la especie.The freshwater crayfish, Cherax quadricarinatus, have many biological and commercial characteristics which turn it into a suitable species for aquaculture. Nevertheless, productive breeding has been hardly significant in Argentina due to different reasons, such as the absence of breeding technologies, the bad choice of the breeding sites, and mainly to the lack of the ―seed" in the different stages of the commercialization process. Due to the scarce available information on the breeding of this species, the following general objectives were considered: to evaluate and compare the effects of commercial feeds, as well as specifically formulated feeds for this species based on its digestive physiology; to study the daily secretion pattern of the digestive enzymes, and its possible modification based on the time of feeding and the fasting period; to evaluate the inclusion of squid meal as an attractant, and analyze the effect of food availability on the activity of digestive enzymes after a short or moderate starvation; and to study the effect of extended starvation and subsequent feeding on the biochemical and physiological parameters of C. quadricarinatus. The animals fed with the specifically formulated feed, showed a good physiological condition according to digestive enzymatic activity, and a conserved tissue structure of the digestive gland. Notwithstanding, the designed diet for this species presented low in vitro protein digestibility. The digestive enzymes secretion did not show a daily secretion pattern, and the moment of feeding (morning or evening) affected the activity of digestive enzymes. Moderate starvation caused modifications in the pattern of the daily secretion of digestive enzymes. The squid meal did not act as an attractant for C. quadricarinatus, whereas food availability after a short starvation period did not modify the activity of digestive enzymes. On the contrary, such activity was altered by food availability when animals were previously exposed to an extended starvation. In consideration of the observed results on food availability, and other author’s previous studies, it is proposed a possible way of regulation of the activity of digestive lipase. Finally, the extended fasting caused a reduction in the energetic reserves (glycogen and lipids), reduced levels of glutathione, activity of lipase and proteinase and alterations in the cellular and tissue structure of the digestive gland, even though it did not increase the oxidative damage. The subsequent feeding, after extended starvation, brought the restoration of all previously described parameters. The present thesis contributes with new and meaningful information on the physiological responses of freshwater crayfish, C. quadricarinatus, which could be very useful for the breeding of this species.Fil:Sacristán, Hernán Javier. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Glycogen levels in midgut gland of Lithodes santolla after starvation

<div>Male king crab (Lithodes santolla) were collected from the Beagle Channel (Tierra del Fuego, southern Argentina) using baited traps and fishing boats.Twenty four king crabs in intermoult stage (114 mm LC) were placed in individual containers with chilled seawater (6±1°C) under continuous aeration. The first day of the assay (time 0, initial control), 6 animals were dissected and their midgut gland was extracted. The remaining crabs were not fed until day 30, 45 or 60. At each time, 6 animals were randomly dissected.<br></div><div>Glycogen concentration in the midgut gland was measured based on Lo´s protocol (Lo et al 1970).</div><div><div><div><p></p></div></div></div

Effect of attractant stimuli, starvation period and food availability on digestive enzymes in the redclaw crayfish Cherax quadricarinatus (Parastacidae)

Chemical stimuli in crayfish have been extensively studied, especially in the context of social interactions, but also to a lesser extent in relation to food recognition and the physiological response of digestive enzymes. This is particularly important in commercial species in order to optimize the food supplied. The first objective of this study was to determine whether incorporation of squid meal (SM) in food (base feed, BF) acts as an additional attractant for Cherax quadricarinatus and, if so, the concentration required for optimal effectiveness. Incorporation of SM was evaluated through individual and group behavioral tests. The second objective was to analyze the effect of food availability on behavior and level of digestive enzyme activity after short-term (48 h) and long-term (16 d) starvation periods. To assess the effect of either starvation period, 3 different treatments were conducted: no feed (control), available BF, and BF present but not available. Individual and group behavior showed no differences among treatments with different percentages of SM inclusion in BF. The time spent in chambers with different percentages of SM was similar in all treatments. Levels of amylase activity and soluble protein, as a function of food availability after a short- or long-term starvation period, were not altered. Digestive enzyme activity was not affected after 2 d of starvation in response to the treatment. However, change was observed in enzymatic profiles after juveniles were deprived of food for 16 d. The main responses were given by lipase, protease and trypsin activity. Based on previous studies and the present results, we propose a hypothesis for a possible regulation of the digestive and intracellular lipase activities depending on food availability.Fil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Nolasco Soria. Héctor. Centro de Investigaciones Biológicas del Noroeste; MéxicoFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Reservas energéticas de la centolla Lithodes santolla de la Costa Atlántica de Tierra del Fuego, Banco Burdwood y Canal Beagle

Análisis bioquímicos y enzimáticos de la glándula digestiva y ovario de la centolla Lithodes santolla en 3 sitios de muestreo con diferentes presiones de pesca (Canal Beagle y Costa Atlántica de Tierra del Fuego) o sin presión de pesca por ser una área protegida (Banco Burdwood)Fil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Di Salvatore, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Lovrich, Gustavo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Benthic diatoms from Potter Cove, 25 de Mayo (King George) Island, Antarctica: mucilage and glucan storage as a C-source for limpets

Biofilms were allowed to develop on ceramic tiles placed in closed containers on the shore of Potter Cove, 25 de Mayo (King George) Island. Water pumping from the cove inside the containers extended for 25 days. Diatoms were the dominant microalgae in these biofilms, which were removed from a set of tiles to a) characterize the extracellular mucilage, b) carry out floristic determination and c) perform grazing experiments with the limpet Nacella concinna. Biofilms mucilaginous matrix consisted of proteins and carbohydrates. Room temperature aqueous extraction of the freeze-dried material rendered a fraction enriched in the storage glucan chrysolaminarin, its identity confirmed by methylation structural analyses. Hot water extracted products showed greater heterogeneity in monosaccharide composition, including glucose, mannose, galactose, fucose, xylose and rhamnose. Diatom identification revealed that Pseudogomphonema kamtschaticum was the dominant species followed by several Navicula species, Nitzschia pellucida and Synedra kerguelensis. Photographical survey of colonized tiles placed in glass flasks together with a specimen of Nacella concinna exhibited between 5 and 30% removal of the biofilms coverage after 24 h of exposure to the limpet, suggesting that EPS and chrysolaminarin constitute a C-source for the gastropod.Fil: Daglio, Yasmin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Ansaldo, Martin. Instituto Antártico Argentino; ArgentinaFil: Rodríguez, María C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentin