Osmar Nusetti

Biochemical composition and energy allocation in the tropical scallop Lyropecten (Nodipecten) nodosus during the months leading up to and following the development of gonads

We quantified biochemical constituents of the major body components of the scallop Lyropecten nodosus (initially measuring 9.4 mm in shell height) cultured at 8, 21 and 34 m in depth in the Golfo de Cariaco, Venezuela, to evaluate the allocation and mobilization of energy in the organisms during periods of somatic and gonadal growth, and during periods of environmental stress. A marked decrease in muscle carbohydrates with depth was associated with a general decrease in the growth rate of the scallops. Protein in the digestive gland and carbohydrates in the muscle and remaining tissues dropped during maximal gonadal growth, suggesting that these tissues contributed energy for gonadal production. Furthermore, during the reproductive period, scallops at 21 m made greater use of lipids in the digestive gland than individuals at 8 m, probably due to the decreased availability of phytoplankton at 21 m. During the last 2 months of our study, when scallops that were energetically depleted by reproduction were faced with low food availability, high temperatures and colonization by fouling organisms, protein levels in remaining tissues decreased and lipid levels stabilized. The relative importance of growth and deposition of reserves in somatic tissues was influenced by reproductive state and prevailing biological and thermal conditions.

Respuestas inmunológicas y cicatrización en el poliqueto Eurythoe complanata (Annelida: Amphinomidae) expuesto a cobre

Polychaetes exposed to 0.4 mg Cu +2 L –1 (2.14 mg CuSO4 5H2O L –1 ; 30% 96 h-LC50) for seven days and control individuals were divided into three groups: the first two were sensitized and non-sensitized with Micrococcus lysodeikticus, and the third was sensitized with heat-killed yeast. Lysozyme activity was tested in the first two groups and phagocytosis in the third one. Lysozyme was measured at 2 h and phagocytosis 15 min after immune sensitization. The effect of copper on wound healing was also examined in the polychaetes. For this, the polychaetes exposed and not exposed to copper were cut in two halves, and the body fragments were held in aquaria containing clean seawater, and the cicatrization was periodically observed. The lysozyme and phagocytosis responses were induced by the sensitization; however, these responses were inhibited after the metal exposure. On the other hand, 60–80% of the body fragments from the control group healed within four days, whereas the copper-treated individuals did not show cicatrization in the same period of time. In conclusion, the inhibition of the experimental activation of lysozyme and phagocytosis, and of wound healing in the polychaete Eurythoe complanata exposed to acute copper exposure, suggests the metal’s potential toxicity on the physiological mechanisms that modulate the innate immunity in annelids, whose alteration could affect their tolerance to microbial infection.

Crystal Structure and Superoxide Dismutase Activity of [Cu(Imidazole)2(Quinoline)Cl2]·0.5[Cu(Imidazole)4Cl2]

The preparation, spectroscopic properties and crystal structure of (bis-imidazole)quinoline-copper(II) dichloride [Cu(Im)2(quin)Cl2] (Im = imidazole, quin = quinoline) and tetraimidazole-copper(II)-dichloride [Cu(Im)4Cl2] are reported. Both cocrystallize on the triclinic system, space group P-1, with cell constants a = 8.095(5) Å, b = 12.141(5) Å, c = 13.847(5) Å, α = 108.816(5)°, β = 104.173(5)°, γ = 94.965(5)° and Z = 2. In the [Cu(Im)2(quin)Cl2] complex the copper(II) ion is coordinated to two imidazole molecules, to one quinoline and two chlorine ions, with the copper(II) ion in a distorted trigonal bipyramidal coordination geometry. In the [Cu(Im)4Cl2] complex, the copper(II) ion has a distorted octahedral coordination geometry. The superoxide dismutase mimetic activity of the complexes was investigated using the indirect xanthine-xanthine oxidase-nitroblue tetrazolium method and compared to that of the native enzyme.

PYRUVATE KINASE, PHOSPHOENOLPYRUVATE CARBOXYKINASE, CYTOCHROME C OXIDASE AND CATALASE ACTIVITIES IN CADMIUM EXPOSED PERNA VIRIDIS SUBJECTED TO ANOXIC AND AEROBIC CONDITIONS

ABSTRACT This work concerns the effects of cadmium exposure on the anaerobic and oxidative metabolism in tissues of the hypoxia-tolerant green mussel Perna viridis from Venezuelan coastal waters. The mussels were exposed to different Cd concentrations (0, 20, 40 and 60 µg/L Cd) for 7 days, and were subsequently exposed to anoxia. Prior to anoxia exposure, Cd concentration was determined in the digestive gland and adductor muscle. After 24 h of anoxia, the activities of pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and cytochrome c oxidase (CCO), and catalase (CAT) were measured in the digestive gland and adductor muscle from Cd-treated mussels. Also, effects of the Cd treatments on the median survival time (LT50) during anoxia were determined. The short-term Cd-exposed mussels augmented the metal uptake in the tested tissues in a dose-dependent manner, associated with a concomitant reduction in the ability to withstand anoxia. During normoxic and anoxic conditions, the Cd-cxposed individuals displayed decreased levels of PK, PEPCK, and CCO in comparison with controls, with the change being most evident during anoxia. Conversely, an increase in CAT was observed in Cd-treated organisms. This effect was further potentiated during anoxia. The toxic action of Cd uptake on PK and PEPCK could reduce the tolerance of anoxia, because these are regulatory glycolytic enzymes in mussels. Moreover, the decreased CCO activity could limit the capacity to recuperate from anoxia. The enhanced CAT activity in Cd-exposed organisms may have been in response to H2O2 produced during oxidative stress, and was likely accentuated during anoxia.