Fish are sensitive to temperature, but the intergenerational consequences of maternal exposure to high temperature on offspring behavioural plasticity and underlying mechanisms are unknown. Here we show that a thermal maternal stress induces impaired emotional and cognitive responses in offspring rainbow trout (Oncorhynchus mykiss). Thermal stress in mothers triggered the inhibition of locomotor fear-related responses upon exposure to a novel environment and decreased spatial learning abilities in progeny. Impaired behavioural phenotypes were associated with the dysregulation of several genes known to play major roles in neurodevelopment, including auts2 (autism susceptibility candidate 2), a key gene for neurodevelopment, more specifically neuronal migration and neurite extension, and critical for the acquisition of neurocognitive function. In addition, our analysis revealed the dysregulation of another neurodevelopment gene (dpysl5) as well as genes associated with human cognitive disorders (arv1, plp2). We observed major differences in maternal mRNA abundance in the eggs following maternal exposure to high temperature indicating that some of the observed intergenerational effects are mediated by maternally-inherited mRNAs accumulated in the egg. Together, our observations shed new light on the intergenerational determinism of fish behaviour and associated underlying mechanisms. They also stress the importance of maternal history on fish behavioural plasticity.

The Steindachneridion parahybae is an endangered catfish from Brazil and strategies applied for gametes optimization are necessary. The aim of this study was to assess inseminating doses and water volume upon the fertilization, hatching rates and percentage of normal larvae in S. parahybae. Was used a randomized design in factorial scheme (4×4) with four inseminating doses: 1.0×10 4 , 1.0×10 5 , 1.0×10 6 , 1.0×10 7 spermatozoa oocyte -1 and four volumes of water: 1, 35, 65 and 95mL of water g -1 of oocytes. The combination of doses and volumes were performed in triplicates (n=48). Each incubator (1.5L of useful volume) with 1g of oocytes was considered as an experimental unit. Significant interaction between inseminating doses and volumes of water to the values of the fertilization rates and quadratic effect of doses and volume for the values of hatching rates were observed. The doses and volumes did not influence the percentage of normal larvae (87.70±5.06%). It is recommended the use of 5.5×10 6 spermatozoa oocyte -1 and 1mL of water g -1 of oocytes during in vitro fertilization procedure. These results allowed us to develop new biotechnological strategies applied to the conservation of S. parahybae.O Steindachneridion parahybae é um bagre ameaçado de extinção no Brasil e estratégias aplicadas para a otimização de gametas são necessárias. O objetivo deste estudo foi avaliar doses inseminantes e volume de água sobre os valores das taxas de fertilização, eclosão e larvas normais em S. parahybae. Utilizando-se um delineamento experimental casualizado em esquema fatorial (4×4), com quatro doses inseminantes: 1,0×10 4 ; 1,0×10 5 ; 1,0×10 6 ; 1,0×10 7 espermatozóides ovócito -1 e quatro volumes de água: 1; 35; 65 e 95mL de água g -1 de ovócitos. As combinações de doses e volumes foram realizadas em triplicatas (n=48). Cada incubadora (1,5L de volume útil) contendo 1g de ovócitos foi considerada como uma unidade experimental. Interações significativas entre doses inseminantes e volumes de água para os valores das taxas de fertilização e efeito quadrático das doses e do volume para os valores das taxas de eclosão foram verificadas. As dosagens e os volumes aplicados não influenciaram no percentual de larvas normais (87,70±5,06). Recomenda-se a aplicação de 5,5×10 6 espermatozoides ovócito -1 e a utilização de 1mL de água.g -1 de ovócitos no procedimento de fertilização artificial in vitro. Estes resultados permitiram desenvolver novas estratégias biotecnológicas aplicadas na conservação do S. parahybae.

ABSTRACT. Transportation of live fish is routinely done in aquaculture; therefore, the aim of this study was to analyze the water quality and survival rate of Rhamdia quelen fry (2.55±0.44 g) following 4, 8 and 12h of simulated transportation, at stock densities of 30 and 60 fry 5 L -1 and temperatures 15, 20 and 25 o C. Dissolved oxygen, pH, electrical conductivity, total ammonia, nitrite, nitrate, turbidity, total alkalinity and survival were analyzed. Temperature and time had a significant influence on ammonia, pH, electrical conductivity, and dissolved oxygen levels, and fish died after 12 hours of transportation simulation when kept at 20 and 25ºC. The density directly affected the water quality parameters, such as the increase in electrical conductivity and turbidity, and decrease in dissolved oxygen and pH at the density of 60 fish 5 L -1 . In conclusion, the transportation of R. quelen fry should be carried out at temperatures between 15 and 25°C, for periods of less than 12 hours, and at stock density of up to 6 fish per liter of water so as not to impair the homeostasis of the fry, and consequently, their survival.Keywords: aquaculture; ammonia; loading densities; management; mortality.Qualidade de água e sobrevivência de alevinos de Rhamdia quelen submetidos a transporte simulado em diferentes densidades e temperaturas RESUMO. O transporte de peixes vivos é uma prática comum na aquicultura. Por isso, o objetivo do presente trabalho foi analisar a qualidade de água e sobrevivência de alevinos Rhamdia quelen (2,55±0,44 g) seguindo 4, 8 e 12h de transporte simulado, em densidades de 30 e 60 peixes 5 L -1 e em temperaturas de 15, 20 e 25 o C. Foram analisados: oxigênio dissolvido, pH, condutividade elétrica, amônia, nitrito, nitrato, turbidez, alcalinidade e sobrevivência. A temperatura e o tempo tiveram influência significativa nos níveis de amônia, pH, condutividade elétrica e oxigênio, e verificou-se mortalidades após 12 horas de simulação de transporte nos peixes mantidos a 20 e 25ºC. A densidade influenciou diretamente nos parâmetros de qualidade de água, tais como o aumento da condutividade elétrica e turbidez e a diminuição de oxigênio dissolvido e pH na densidade de 60 peixes 5 L -1 . Em conclusão, recomenda-se o transporte de alevinos de R. quelen em temperaturas entre 15 e 25°C, em períodos inferiores a 12 horas. E a densidade de seis peixes por litro de água não compromete a homeostase dos alevinos, e consequentemente sua sobrevivência.

Steindachneridion parahybae is an endemic catfish to the Paraiba do Sul river basin classified as critically endangered. Little is known about the reproductive management of this species in captivity, adopting for this practice empirical measures. The objectives were to:(1) determine suitable Accumulated Thermal Units (ATUs) at the moment of ovulation in January 2011 and 2012; (2) follow initial larvae rearing in 180, 240 and 300 degreehours. Nine selected females were divided into three experimental groups of three specimens each (replications), distributed at pre-established times: 140, 160, 180, 200, 220, 240, 260, 280 and 300 degree-hours. The females were induced with two doses of 0.5 and 5.0 mg kg -1 of dry carp pituitary, respectively, at an interval of 12 h. The extruded oocytes were kept at average water temperature of 22.35 ± 0.53°C (2011) and 21.88 ± 0.15°C (2012). Fertilization and hatching rates were: 84.22 and 71.33 % at 174.2 ATUs in 2011, and 55.58 % and 36.13 % at 251.0 ATUs in 2012. In January 2012, 900 larvae were distributed in three replications (triplicate) consisting of 100 larvae each and were fed: 120 (second day), 300 (thirdfourth day), 600 (fifth-eighth day), and 1,200 Artemia salina nauplii per larva (ninth-15th day), six times a day. The larvae exhibited mean weight of 523.67 ± 54.42, 496.67 ± 61.98 and 475.00 ± 22.83 mg, length of 17.75 ± 0.57, 17.58 ± 0.51 and 17.45 ± 0.25 cm and survival of 63.95 ± 24.50, 71.71 ± 6.61 and 79.65 ± 0.82 %, when hatched in 180, 240 and 300 ATUs, respectively. The larvae body parameters did not show significant differences at these degree-hours.