The adaptation of rainbow trout to warmer water: oxidative damage in the germinal line

Contemporary evolution was observed in a feral rainbow trout (Oncorhynchus mykiss) population of a thermal stream (Valcheta) in Northern Patagonia, in terms of juvenile thermal tolerance and preferred temperature. Other authors showed that high-temperature treatment applied to male rainbow trout juveniles increased the thermal tolerance in the next generation. This implies a high mutation rate and/or a modified epigenetic inheritance. Comparisons were made among a) a rainbow trout strain adapted in terms of upper thermal tolerance and higher preferred temperature (Valcheta stream), b) a wild temperate stream population (Guillelmo stream), and c) two temperate farmed strains. We examined: Oxidative damage (lipid peroxidation) and activities of antioxidant enzymes; Catalase (CAT), Glutathione S-Transferases (GST), and Superoxide Dismutase (SOD), in liver, testicle, and spermatozoa. Semen fatty acid composition, sperm morphology, sperm motility, and fertilization performance in samples before and after the application of cryopreservation procedures were also evaluated. The observed responses, mainly related to the sperm membrane, reinforces the idea that ROS can affect the germinal line of male rainbow trout juveniles subjected to high water temperature. Our results suggest that the acquired thermal tolerance traits may be part of a wide spectrum of novel characteristics produced as a consequence of an enhanced mutation rate and/or a different DNA methylation pattern, induced by higher temperatures and mediated by ROS.Centro de Investigación y Desarrollo en Criotecnología de Alimento

The adaptation of rainbow trout to warmer water: oxidative damage in the germinal line

Contemporary evolution was observed in a feral rainbow trout (Oncorhynchus mykiss) population of a thermal stream (Valcheta) in Northern Patagonia, in terms of juvenile thermal tolerance and preferred temperature. Other authors showed that high-temperature treatment applied to male rainbow trout juveniles increased the thermal tolerance in the next generation. This implies a high mutation rate and/or a modified epigenetic inheritance. Comparisons were made among a) a rainbow trout strain adapted in terms of upper thermal tolerance and higher preferred temperature (Valcheta stream), b) a wild temperate stream population (Guillelmo stream), and c) two temperate farmed strains. We examined: Oxidative damage (lipid peroxidation) and activities of antioxidant enzymes; Catalase (CAT), Glutathione S-Transferases (GST), and Superoxide Dismutase (SOD), in liver, testicle, and spermatozoa. Semen fatty acid composition, sperm morphology, sperm motility, and fertilization performance in samples before and after the application of cryopreservation procedures were also evaluated. The observed responses, mainly related to the sperm membrane, reinforces the idea that ROS can affect the germinal line of male rainbow trout juveniles subjected to high water temperature. Our results suggest that the acquired thermal tolerance traits may be part of a wide spectrum of novel characteristics produced as a consequence of an enhanced mutation rate and/or a different DNA methylation pattern, induced by higher temperatures and mediated by ROS.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

The aim of this work was to study two aspects of phenotypic plasticity in the Patagonian pejerrey Odontesthes hatcheri (Teleostei: Atherinopsidae) the dependence of the early morphology on developmental time and temperature, and the induction of morphological changes by controlled feeding in juveniles. Newly hatched free embryos, incubated at two different temperatures (13 and 18oC), and juveniles were used for the study and induction of phenotypic plasticity. Body and head shapes were analyzed with geometric morphometrics and linear measurements. Our results showed that shape variation at hatching was related to the bending of the embryo head on the yolk sac, increasing the head-trunk angle due to progressive straightening of the embryo. The head-trunk angle was related with temperature at incubation, with embryos incubated at higher temperature being more bent. Embryos that hatched earlier had bigger yolk sacs than those that hatched later. In juveniles, controlled feeding experiments added new morphological variation to that of wild juveniles. In all comparisons, the slenderness of the head, the size of premaxilla and jaw, and the position of the eye showed an enlarged variation due to controlled feeding. These results will contribute to comprehending the complexity of the morphological variation of O. hatcheri.<br>O objetivo deste trabalho foi estudar a variação morfológica e plasticidade fenotípica do peixe-rei da Patagônia Odontesthes hatcheri (Teleostei: Atherinopsidae), a dependência da morfologia inicial no tempo de desenvolvimento e temperatura, e a indução de alterações morfológicas pela alimentação controlada em juvenis. Embriões recém-nascidos, incubados a duas temperaturas diferentes (13 e 18oC) e juvenis foram utilizados para o estudo de indução de plasticidade fenotípica. Formas do corpo e cabeça foram analisadas com técnicas de morfometria geométrica e medições lineares. Os nossos resultados mostraram que a variação da forma no nascimento foi relacionada com a curvatura da cabeça do embrião no saco vitelino, aumentando o ângulo de cabeça-tronco devido ao endireitamento progressivo do embrião. O ângulo da cabeça-tronco relacionou-se com a temperatura de incubação, com os embriões incubados na temperatura elevada sendo mais curvados. Os embriões que eclodiram mais cedo tinham sacos vitelinos maiores do que aqueles que eclodiram tardiamente. Em juvenis, os experimentos de alimentação controlada adicionaram nova variação morfológica àquela dos juvenis selvagens. Em todas as comparações, a espessura da cabeça, o tamanho da pré-maxila e mandíbula, e a posição do olho mostraram uma maior variação devido à alimentação controlada. Estes resultados irão contribuir para a compreensão da complexidade da variação morfológica de O. hatcheri

Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

The aim of this work was to study two aspects of phenotypic plasticity in the Patagonian pejerrey Odontesthes hatcheri (Teleostei: Atherinopsidae) the dependence of the early morphology on developmental time and temperature, and the induction of morphological changes by controlled feeding in juveniles. Newly hatched free embryos, incubated at two different temperatures (13 and 18oC), and juveniles were used for the study and induction of phenotypic plasticity. Body and head shapes were analyzed with geometric morphometrics and linear measurements. Our results showed that shape variation at hatching was related to the bending of the embryo head on the yolk sac, increasing the head-trunk angle due to progressive straightening of the embryo. The head-trunk angle was related with temperature at incubation, with embryos incubated at higher temperature being more bent. Embryos that hatched earlier had bigger yolk sacs than those that hatched later. In juveniles, controlled feeding experiments added new morphological variation to that of wild juveniles. In all comparisons, the slenderness of the head, the size of premaxilla and jaw, and the position of the eye showed an enlarged variation due to controlled feeding. These results will contribute to comprehending the complexity of the morphological variation of O. hatcheri

Climate change impacts on freshwater fishes: a Patagonian perspective

The fish fauna of Patagonian lakes comprises a small, unique group of native species and several exotic ones. The consequences of environmental changes for Patagonian fish populations vary according to the physiology of the species considered. Several previously predicted facts such as extirpations, extinctions, and translocations have occurred and human actions such as transport, introduction, and stocking of exotic species suggest a more complex future. We discuss the historical biogeography of Patagonian freshwater ichthyofauna to help us better understand their present adaptations and physiological ecology. We also address potential interactions between climate change and processes such as migration, species introductions, and invasions. There is still much to learn from Patagonian fishes to comprehend how these species will endure environmental changes.Fil: Becker, Leandro Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; ArgentinaFil: Crichigno, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; ArgentinaFil: Cussac, Victor Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; Argentin