Nicolás Ortiz

Effect of seasonality on oxidative stress responses and metal accumulation in soft tissues of Aulacomya atra, a mussel from the South Atlantic Patagonian coast

This study investigated the effects of pollution and its interaction with temperature on the oxidative status of the ribbed mussel Aulacomya atra in the southern Atlantic Patagonian coast. Animals were collected from four sites with different degree and type of human activity impact, during the summer and winter of 2011. Seawater chromium, copper, manganese, nickel and zinc concentrations were measured, as well as metal accumulation, lipid peroxidation, protein oxidation, reduced glutathione levels, and enzymatic activities of superoxide dismutase and glutathione-S-transferase in gills and digestive glands. Metal bioaccumulation and oxidative stress responses in both tissues were generally higher in mussels from harbor areas. Water temperature had a remarkable effect on gill SOD activity and protein oxidation during winter in mussels from all locations. Methodologically, we conclude that measuring both metal bioaccumulation and oxidative stress responses allowed for a more accurate assessment of the biological effects of metal present in seawater.

Validation of macroscopic maturity stages of the Patagonian red octopus Enteroctopus megalocyathus

Fil: Ortiz, Nicolas. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Nacional Patagonico; Argentina

Analysis of the morphological variation of Doryteuthis sanpaulensis (Cephalopoda: Loliginidae) in Argentinian and Brazilian coastal waters using geometric morphometrics techniques

Shape variation of individuals from three locations, two from Argentina and one from Brazil, was analysed by geometric morphometrics techniques. Individuals were weighed, measured, sexed, assigned to a maturity stage and photographed. For the analysis, two landmark configurations were used: one of nine landmarks (9L) and another of 25 landmarks (25L). To visualise shape variation, a principal component analysis (PCA) on Procrustes coordinates was conducted. The percentage of total shape variation explained by the 9L configuration was 80.5% (PC1: 61% and PC2: 19.5%), while the percentage for the 25L configuration was 76.4% (PC1: 54.8% and PC2: 21.6%). Based on this, shape analyses were performed using only the 9L configuration. The PCA results indicated that specimens show a large overlap between the categories based on sex and maturity stage. When location is considered, squid shape from São Sebastião and Rawson Port were very similar, while in Nuevo Gulf, the presence of two different morphological groups were observed: one similar to São Sebastião and Rawson Port, and the other with a morphology typical of Nuevo Gulf. Thus, two different morphotypes were defined: (i) morphotype of the continental shelf and (ii) morphotype typical of the gulf. The continental shelf morphotype is characterised by larger fins and wider mantle than the gulf morphotype. These results suggest that the morphotypes of Doryteuthis sanpaulensis are adaptations to oceanographic regimens.

Trace metals and oxidative status in soft tissues of caged mussels ( Aulacomya atra ) on the North Patagonian coastline

This study investigated metal accumulation and oxidative effects in mantle, gill and digestive gland of the ribbed mussel Aulacomya atra from the Argentinean North Patagonian coastline. Mussels were transplanted over an 18-month period from a site with low anthropogenic impact to a harbor site with higher seawater concentration of aluminum, chromium, copper, manganese, nickel and zinc. Total trace metal concentration in seawater did not change throughout the 18-month transplant in either site. A. atra bioaccumulated metals in digestive gland, gills and mantle at different levels. Digestive gland had the highest concentration of metals, especially towards the end of the transplant experiment in the harbor area. Mussels transplanted to the harbor site experienced an upregulation in their antioxidant system, which likely explains the lack of oxidative damage to lipids despite higher metal accumulation. These results demonstrate that A. atra selectively accumulates metals from the water column and their prooxidant effects depend on the tissue antioxidant defenses and the exposure time.

Reproductive status, antioxidant defences and lipid peroxidation in Octopus tehuelchus (Cephalopoda: Octopodidae) females

ABSTRACT As in other semelparous cephalopods, Octopus tehuelchus females enter a senescent state after spawning. In several taxa, damage to macromolecules that result from an imbalance between antioxidant defences and the production of reactive oxygen species (i.e. oxidative stress) has been postulated as one of the physiological costs of reproduction and one factor that contributes to ageing. In this work, we evaluate whether enzymatic and non-enzymatic antioxidant defences are conditioned by reproductive status in O. tehuelchus obtained from a wild population. The main antioxidant defences, catalase (CAT), superoxide dismutase (SOD), reduced gluthation (GSH) and lipid peroxidation (TBARS), were assessed in somatic and reproductive tissues from octopus females, at immature, mature and spent stages. Oviducal glands showed an increase in TBARS that coincides with a decrease in GSH when females reach a spent stage. No significant changes were observed in the assayed parameters on the ovary wall, digestive gland, mantle and gills along maturity stages. CAT activity was undetectable in most analysed tissues, SOD activity and GSH were similar to or lower than in other cephalopods, while average TBARS levels in somatic tissues were at least one order of magnitude higher than levels found in other molluscs. Our results show that during sexual maturation and after natural oxidative stress conditions (spawning), only oviducal glands show changes that can be linked with the physiological processes of different reproductive status. The low antioxidant defences and the flat protective reactions after spawning could be associated with the semelparous life history of this species.