Analía F. Pérez

Reproductive biology and energy allocation of the sea star Cosmasterias lurida (Echinodermata: Asteroidea) from the Beagle Channel, Tierra del Fuego, Argentina

Abstract Seasonal fluctuations in environmental factors at high-latitude marine regions have a strong influence on the reproductive cycles of echinoderms. The purposes of this study on a population of Cosmasterias lurida in the Beagle Channel are to describe the reproductive cycle through histological analyses, to characterize the pattern of gonad and somatic indices, to determine the energy content of different organs and their temporal variation and to establish the pattern of energy allocation. During the study period, from August 2010 to June 2011, four seasonal samplings were performed in the subtidal zone of Ushuaia Bay. Indices (gonad, pyloric caeca and stomach), gonadal histology, organic matter and calorimetric measurements were determined. Gametogenesis begins in February and continues until June when oocyte size increases. The gonadal maximum development and gamete releasing take place between August and December. Temporal variation of energetic reserves in gonads occurs through the variation in gonad mass, with a GI major peak and energy content during August. Stomach and pyloric caeca show their maximum energy accumulation during June, while decrease of organic matter of the body wall takes place from August to December. The population of C. lurida from Beagle Channel suggests an annual reproductive cycle with two maturation events and the influence of water temperature on maturation and releasing of gametes. Different patterns of energy allocation to gonads between sexes were observed, with a greater energy investment in females than in males. Pyloric caeca, stomach and body wall were proposed as energy reservoirs for gonadal maturation and spawning.

Relationship between energy allocation and gametogenesis in Aulacomya atra (Bivalvia: Mytilidae) in a sub-Antarctic environment

Resumen es: Se analizo la gametogenesis y la variacion temporal en la asignacion de energia a diferentes organos de Aulacomya atra del Canal Beagle (Tierra del Fuego...

Environmental concentrations of azinphos-methyl cause different toxic effects without affecting the main target (cholinesterases) in the freshwater gastropod Biomphalaria straminea

Organophosphate insecticides (OPs) are commonly used in Argentina and around the world for pest control in food crops. They exert their toxicity through the inhibition of the enzyme acetylcholinesterase. In the present study, we aimed to evaluate biochemical and reproductive effects in Biomphalaria straminea, a freshwater gastropod naturally distributed in Argentina, of subchronic exposures to environmental azinphos-methyl concentrations (20 and 200 µg L-1). For biochemical parameters, adult organisms were exposed for 14 days and the activity of cholinesterases (ChEs), carboxylesterases (CEs), glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), the production of reactive oxygen species (ROS), the total antioxidant capacity (TAC), glycogen and proteins were determined. For reproductive parameters, the egg masses of B. straminea were exposed to azinphos-methyl for one month, and the hatching time and success as well as the offspring survival were registered. We found different toxic effects elicited by the insecticide on the studied biomarkers. CEs activity was significantly inhibited while CAT and GST activities, ROS production and TAC were significantly increased, with respect to the solvent control group. ChE and SOD activities and protein and glycogen contents were not altered by azinphos-methyl. The hatching time and success were not statistically different from control. Nevertheless, the offspring survival was severely affected by the insecticide. Our results show that the primary target of the insecticide (ChE) was not inhibited but CEs, GST, CAT, ROS, TAC and offspring survival were sensitive biomarkers and valuable endpoints for subchronic toxicity assessments in this species.