Inorganic osmolytes and enzymatic biomarkers from the manabi oyster (Crassostrea cf. corteziensis) in response to saline stress.

Abrupt drops in salinity that occur in tropical estuaries during the equatorial rainy season led to hyposaline conditions which may reduce the populational density of oysters. To assess the effect of saline stress on physiological and metabolic responses of the Manabi oyster (Crassostrea cf. corteziensis) was exposed to 35, 30, 20,10 and 5‰ concentrations during 96 h. Inorganic osmolytes, pH, salinity, haemocyanin and protein concentration in the plasma as well as the number of oysters with closed valves were recorded. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and catalase (CAT) activity were analysed. Inorganic osmolytes and internal salinity were elevated in oysters exposed to 35, 10 and 5‰. A significant number of oysters with valve closure was observed in 10 and 5‰, which coincided with a decline in physiological pH and changes in haemocyanin concentrations. AST activity and AST/ALT ratio were reduced under 35, 10 and 5‰, and CAT increased in oysters exposed to 35‰; but protein concentration, LDH and ALP did not show significant variations. Metabolic adjustment and behavior of the Manabi oyster could explain tolerance and survival (at least for a short term) to hyposaline stress in tropical estuarine ecosystems.

Parámetros hemocitarios y química de la hemolinfa en reproductores de la concha prieta Anadara tuberculosa (Arcoida: Arcidae)

Con motivo de conocer el estado de salud de poblaciones silvestres de la concha prieta Anadara tuberculosa se estudiaron los parámetros hemocitarios (viabilidad, conteo total y diferencial, estabilidad lisosomal, fragilidad osmótica) y la química sanguínea (hemoglobina-Hb, proteínas, triglicéridos, glucosa, lactato deshidrogenasa-LDH y catalasa-CAT). Se extrajo hemolinfa en reproductores salvajes aparentemente sanos colectados en la isla Corazón, río Chone, Ecuador. La viabilidad celular fue elevada, con presencia de 5 morfotipos: eritrocitos (74%), granulocitos traslucidos (6%), amebocitos (3%), hialinocitos (12%), blastocitos (5%). Los hemocitos presentaron membranas lisosomales estables al rojo neutro durante 240 min y una fragilidad osmótica media (FO50) de 4.8‰. Las concentraciones de Hb, proteínas, lípidos y glucosa denotan la función respiratoria y reservas energéticas durante los cambios de marea. La actividad de LDH está vinculada al metabolismo anaeróbico y CAT a la capacidad de mantener el equilibrio redox del sistema inmunitario. Los parámetros hemocitarios y química de la hemolinfa pueden servir como índices fisiológicos normales de referencia en reproductores de A. tuberculosa.

In this work we studied the health status of wild populations of the black shell Anadara tuberculosa, haemocyte parameters (viability, total and differential count, lysosomal stability, osmotic fragility) and blood chemistry (haemoglobin-Hb, proteins, triglycerides, glucose, lactate dehydrogenase-LDH and catalase-CAT). Haemolymph was extracted from apparently healthy wild broodstock collected from Corazón Island, Chone River, Ecuador. Cell viability was high, with 5 morphotypes present: erythrocytes (74%), colorless granulocytes (6%), amebocytes (3%), hyalinocytes (12%), blastocytes (5%). Haemocytes showed stable lysosomal membranes to neutral red for 240 min and a mean osmotic fragility (OF50) was 4.8‰. Hb, protein, lipid and glucose concentrations denote respiratory function and energy reserves during tidal changes. LDH activity is linked to anaerobic metabolism and CAT denotes the ability to maintain the redox balance of the immune system. The haemocitary parameters and haemolymph chemistry can serve as normal physiological reference indices in A. tuberculosa broodstock.

Modulation of innate immune responses in the flame scallop Ctenoides scaber (Born, 1778) caused by exposure to used automobile crankcase oils.

The used automobile crankcase oils are potential sources of contaminant elements for the coastal-marine ecosystems, affecting mainly the immunological system of organisms that feed by filtration, e. g. scallops. This study examined the effects of a water-soluble fraction of used automobile crankcase oils (WSF-UACO) on innate cellular- and humoral immune responses of the flame scallop Ctenoides scaber. The scallops were exposed to ascending concentrations of 0, 0.001, 0.01, and 0.1 of WSF-UACO under a static system of aquaria during 7 and 13 d. The viability, haemocyte total count (HTC), lysosomal membrane destabilization (LMD), phagocytosis, and protein concentration in hemolymph samples withdrawn taken from the blood sinus as well as lysozyme activity of the digestive gland were measured as immune endpoints. A decrease in cellular immune competence in scallops exposed to WSF-UACO was observed, with significant impairment of viability, HTC, and phagocytosis. LMD index increased about exposure concentrations, and plasma protein concentrations augmented to 0.01 and 0.1% during 13 d. Lysozyme activity increased in scallops exposed to WSF-UVCO during 7 d, to level off in the chronic period. Lysozyme activity and enhanced plasma proteins could act as compensatory responses when cell parameters tend to fall, helping to the regulation of microbial microflora and possible invasion of pathogenic microbes as well as defense against xenobiotics. The results demonstrate that the immunological responses of C. scaber are highly sensitive to the complex chemical mixture of contaminants, and it could be used for evaluating biological risks of hazardous xenobiotics in tropical marine environments. Republic of Ecuador.

Colorless spherule cells and lysozyme contribute to innate immunological responses in the sea urchin Lytechinus variegatus, exposed to bacterial challenge.

The sea urchin Lytechinus variegatus is considered a good candidate for aquaculture, but bacterial diseases are a major challenge in culture conditions. The innate immunological defenses of L. variegatus to bacterial challenges were assessed through hematology parameters, in vitro phagocytosis, lysozyme activity and total plasma protein concentrations in cell-free coelomic fluid. Adult sea urchins were inoculated with Microccocus lysodeikticus, Escherichia coli and Vibrio parahaemolyticus in the cavity coelomic. Filtrated and sterile seawater (FSW) injected and non-injected sea urchins were used as control groups. Righting time, external aspects and behavior of sea urchins were evaluated. Twenty-four hours post-inoculation, we found an increase in the population of colorless spherule cells (CLS), phagocytosis, and humoral responses in sea urchins challenged by bacterial inoculations. Righting time was not affected by the treatments and apparent external signs of disease were not observed at least during 96h post-inoculation. The immunological system of L. variegatus quickly eliminated pathogenic microorganisms. CLS and lysozyme activity cooperate in the immune defenses of L. variegatus, showing an extraordinary efficiency for adjusting the immune defenses under stress caused by microbes. We recommend that the cellular and humoral markers serve as routine tests to monitor health status in sea urchins.

Antioxidant defenses of flame scallop Ctenoides scaber (Born, 1778) exposed to the water-soluble fraction of used vehicle crankcase oils.

Used vehicle crankcase oils are a source of contamination in Caribbean marine environments and may alter the oxidative balance of organism that inhabiting coastal ecosystems. This paper aims to evaluate effects of a water-soluble fraction of used vehicle crankcase oils (WSF-UVCO) on the antioxidant responses of the flame scallop Ctenoides scaber. The organisms were exposed to ascending sublethal concentrations 0, 0.001, 0.01 and 0.1 % of WSF-UVCO in a static system of aquaria during one week. Subsequently activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) as well as concentrations of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were determined in the digestive gland, adductor muscle and gills. SOD, CAT, GST and TBARS increased in digestive gland of organisms exposed to WSF-UVCO at medium and highest concentrations, with a concomitant decrease in GPX and GR activities. In adductor muscle CAT decreased, but GR rose with exposure to 0.01 and 0.1 % WSF-UVCO; in gills, GST rose through all WSF-UVCO concentrations, and SOD, CAT and GR increased only at 0.1 %. The fluctuations in antioxidant enzymes and GST activities point out possible adjustments to control ROS production and detoxification of xenobiotics. These biochemical responses may guarantee the oxidative balance in flame scallop during short term exposure to low concentrations of WSF-UVCO. C. scaber appears suitable as an experimental organism for evaluating biological risks of sublethal exposure to hazardous xenobiotics in tropical marine environments.

Ciclo gametogénico del erizo marino Echinometra lucunter (Echinometra: Echinoidea) en el Noriente de Venezuela / Gametogenic cycle of the rock boring urchin Echinometra lucunter (Echinodermata: Echinoidea) in northeastern Venezuela

Resumen El ciclo gametogénico y el índice gonadosomático (IG) del erizo negro Echinometra lucunter fue examinado entre junio de 2010 y noviembre de 2011 en el noreste de Venezuela (Isla de Lobos, Península de Araya y Ensenada de Turpialito, Golfo de Cariaco). Las gónadas están integradas por extensos acinos ramificados, recubiertos por tejido conectivo, seguido de una capa delgada de células que se diferencian en fagocitos nutritivos y gametos, los cuales cambian en sus proporciones y tamaños con los estadios de maduración. Generalmente, en ambas localidades se presentaron varios estadios de maduración, con desoves simultáneos. En Isla Lobos predominaron los individuos en estado de reserva con un corto período de madurez sexual, mientras que en la Ensenada de Turpialito predominaron organismos maduros y desovados. El IG sugiere que los desoves están asociados a las precipitaciones estacionales de la región; mostrando una estrategia reproductiva conservadora, acumulando reservas energéticas en el periodo de mayor producción primaria asociada a los periodos de surgencia costera, cuando la energía de los fagocitos nutritivos es transferida a los gametos hasta su maduración y expulsión al medio ambiente. Las características biológicas y reproductivas de los organismos en Turpialito mostraron elevados IG y mayor tejido gonadal para consumo comercial.

Abstract Several species of sea urchins are a potential resource for the production of gonads for consumption in Venezuela. We studied the gametogenic cycle and the gonadosomatic index (GSI) of the rock boring urchin Echinometra lucunter between June 2010 and November 2011 in northeastern Venezuela (Isla Lobos, Península de Araya and Turpialito, Gulf of Cariaco). The gonads are composed of long ramified acini, covered by connective tissue, followed by a thin layer of cells that differentiate into nutritive phagocytes and gametes, which change in their proportion and size with the maturity stage. Generally, several maturity stages were observed in both locations, showing simultaneous spawning. At Isla de Lobos the individuals in reserve stage predominated with a short period of sexual maturity, while mature and spawned individuals predominated in Turpialito. The GSI suggests that the greatest spawning activity is associated to the rainy season; showing a conservative reproductive activity, accruing energetic reserves during the period of higher primary productivity associated to coastal upwelling, when the energy of nutritive phagocytes is transferred to gametes, for gamete development and spawning. The biological and reproductive characteristics of individuals at Turpialito showed higher GSI having more gonadal tissue for commercial consumption. Rev. Biol. Trop. 63 (Suppl. 2): 273-283. Epub 2015 June 01.

Dieta del erizo negro Echinometra lucunter (Echinometra: Echinoidea) en el Nororiente de Venezuela / Diet of the black sea urchin Echinometra lucunter (Echinometra: Echinoidea) in the northeast of Venezuela

Resumen Mensualmente entre junio 2010 y agosto 2011 en la ensenada de Turpialito, Golfo de Cariaco, Venezuela, se recolectaron macroalgas e identificaron, y ejemplares de Echinometra lucunter con diámetro de testa 41.04 ± 6.60 mm para examinar el contenido estomacal y el índice de llenado. Se identificaron 65 especies de macroalgas, pertenecientes a los Phylla Rhodophyta, Heterokontophyta y Chlorophyta. La mayor biomasa anual la presentaron Halimeda opuntia (56.5 g.m-2), Acanthophora spicifera (15.94 g.m-2), Sargassum vulgare (15.28 g.m-2) y Centroceras clavulatum (12.26 g.m-2). Los ítems alimenticios más frecuentes fueron las macroalgas filamentosas: Sphacelaria sp. (546) y Herposiphonia sp. (441) y la foliácea Dictyota sp. (410), y entre los invertebrados esponjas (155), moluscos bivalvos (70) y crustáceos cirrípedos (65). El ID osciló entre 0.8 y 6.0% (2.6 ± 1.21 %), con máximos en diciembre 2010 (6.0 ± 2.21 %), abril (4.3 ± 0.34 %) y junio 2011 (4.0 ± 1.79 %), con oscilaciones mensuales asociadas a los períodos de surgencia y estratificación. El conocimiento de las características principales de la dieta, es necesaria para proponer planes de cultivo y de conservación de la especie.

Abstract Echinometra lucunter is relatively abundant in the Venezuela coast, however no details are known about its diet. We compare the stomach contents and repletion index of E. lucunter with macroalgae available in their environment (June 2010-August) and the nutrient cycle at the Golfo de Cariaco. Seventy-one species of macroalgae were identified: Rhodophyta (45), Heterokontophyta (11) and Chlorophyta (15). The mean testa diameter was 41.04 ± 6.60 mm. The food preferences included filamentous, siphonal and calcaeous macroalgae; main food items were the filamentous macroalgae Sphacelaria sp. and Herposiphonia sp., and foliose Dictyota sp., including invertebrates such as sponges, bivalves and barnacle crustaceans. The repletion index was 0.8 - 6.0 % (2.6 ± 1.21 %), maximum values were associated to primary productivity cycle, i.e. December 2010 (6.0 ± 2.21 %), April (4.3 ± 0.34 %), June 2011 (4.0 ± 1.79 %). Food preferences could be associated to the upwelling season and productivity cycle. Rev. Biol. Trop. 63 (Suppl. 2): 233-242. Epub 2015 June 01.