RESUMO

The exposure of adult fish to warm or high temperatures is known to impair reproduction, yet the long-term reproductive impacts for treatments at early life are not well clarified. This study aimed to evaluate the effects of warm temperature (WT) during juvenile stage on gonad maturation, gamete quality, and offspring thermotolerance in rainbow trout. While the comparison of basic reproductive parameters in WT females did not reveal any kind of impairment, many WT males showed an atrophied, undeveloped gonad, or a smaller testis with lower milt volume; sperm quality parameters in WT males and deformity rates in the respective progeny were also highly affected. However, despite of such negative effects, many of the remaining progeny presented better rates of survival and growth when exposed to the same conditions as those of parental fish (WT), suggesting that thermal stress in parr stage males elicited intergenerational thermotolerance after a single generation. The present results support that prolonged warming stress during early life stages can adversely affect key reproductive aspects, but contrastingly increase offspring performance at upper thermal ranges. These findings have implications on the capacity of fish to adapt and to cope with global warming.

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RESUMO

Albinism is the most common color variation described in fish and is characterized by a white or yellow phenotype according to the species. In rainbow trout Oncorhynchus mykiss, aside from yellow-albino phenotypes, cobalt blue variants with autosomal, recessive inheritance have also been reported. In this study, we investigated the inheritance pattern and chromatophores distribution/abundance of cobalt blue trouts obtained from a local fish farm. Based on crosses with wild-type and dominant yellow-albino lines, we could infer that cobalt blue are dominant over wild-type and co-dominant in relation to yellow-albino phenotype, resulting in a fourth phenotype: the white-albino. Analysis of chromatophores revealed that cobalt blue trouts present melanophores, as the wild-type, and a reduced number of xanthophores. As regards to the white-albino phenotype, they were not only devoid of melanophores but also presented a reduced number of xanthophores. Cobalt blue and white-albino trouts also presented reduced body weight and a smaller pituitary gland compared to wild-type and yellow-albino phenotypes. The transcription levels of tshb and trh were up regulated in cobalt blue compared to wild type, suggesting the involvement of thyroid hormone in the expression of blue color. These phenotypes represent useful models for research on body pigmentation in salmonids and on the mechanisms behind endocrine control of color patterning.

Assuntos

RESUMO

Triploid fish are usually sterile. Thus, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth. The present study aimed to investigate differences in the metabolic substrates, lipids and proteins, between storage tissues from diploid and triploid female rainbow trout. Monthly, metabolic substrates were quantified in liver, muscle, and ovaries, which were collected during the first reproductive cycle. In general, it was possible to identify a seasonal and similar deposition of metabolites in different tissues of 2n and 3n females, mainly at early stages of gonadal maturation. However, from the stages 5-6, the ovaries showed great differences between ploidies, with higher concentration of lipids and protein in 2n females. This result reflects the incorporation of vitellogenin in oocytes, which is a process that does not occur in 3n females. It was possible to observe seasonal hepato-somatic index changes in 2n females, with higher values observed in the post-ovulatory stage, and the triploid animals showed lower values compared to 2n, with no seasonal difference. Viscero-somatic index can reflect the mobilization of substrates, with higher values found for 2n females in stage 5-6, which is the period of active mobilization of tissue substrates.

Assuntos

RESUMO

Triploid fish are usually sterile. Thus, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth. The present study aimed to investigate differences in the metabolic substrates, lipids and proteins, between storage tissues from diploid and triploid female rainbow trout. Monthly, metabolic substrates were quantified in liver, muscle, and ovaries, which were collected during the first reproductive cycle. In general, it was possible to identify a seasonal and similar deposition of metabolites in different tissues of 2n and 3n females, mainly at early stages of gonadal maturation. However, from the stages 5-6, the ovaries showed great differences between ploidies, with higher concentration of lipids and protein in 2n females. This result reflects the incorporation of vitellogenin in oocytes, which is a process that does not occur in 3n females. It was possible to observe seasonal hepato-somatic index changes in 2n females, with higher values observed in the post-ovulatory stage, and the triploid animals showed lower values compared to 2n, with no seasonal difference. Viscero-somatic index can reflect the mobilization of substrates, with higher values found for 2n females in stage 5-6, which is the period of active mobilization of tissue substrates.(AU)

Assuntos

RESUMO

Roes of rainbow trout (Oncorhynchus mykiss) can be used to produce caviar substitutes, resulting ina high-value added product. This study evaluated the market potential of rainbow trout roe inCampos do Jordão City (São Paulo State, Brazil) (22°44′20″S, 45°35′27″W) and the economic aspectsof its production, considering two scenarios: production in existing processing plants (scenario A)and building a plant for its production (scenario B). To estimate the net present value rates (NPV),we used different asking prices (US$ 8.50, US$ 10.00 and US$ 12.50) and interest rates (11%). Themarket research indicated a great potential for the caviar substitute, perceived as a differential ingastronomy. The results showed economic viability in scenario A, with satisfactory profitabilityand return on venture capital for the short-term at different prices. In scenario B, economic viabilityis attained at the highest price, US$ 12.50; all other simulations require careful consideration fromthe investor.

Ovas de truta arco-íris podem ser utilizadas para a confecção de sucedâneo de caviar, resultandoem produto de alto valor agregado. Este estudo objetivou avaliar o potencial de mercado doproduto no município de Campos do Jordão – SP (22°44′20″S, 45°35′27″W), e os aspectoseconômicos da sua produção nas seguintes simulações: produção em estrutura de processamentopreviamente existente (simulação A), construção de estrutura específica para sua produção(simulação B), diferentes preços de venda (R$ 19,00; R$ 22,50 e R$ 28,00), e taxa de juros de 11%para estimativa do valor presente líquido (VPL). O estudo de mercado indicou grande potencialpara o sucedâneo, visto como diferencial na gastronomia. Os resultados demonstraram aviabilidade do investimento para todas as simulações da condição A, com alta rentabilidade erecuperação do investimento em curto prazo. A condição B apresentou viabilidade apenas para opreço de US$ 12.50; todas as outras simulações para esta condição requerem análise cuidadosa porparte do investidor.

Assuntos

RESUMO

Roes of rainbow trout (Oncorhynchus mykiss) can be used to produce caviar substitutes, resulting ina high-value added product. This study evaluated the market potential of rainbow trout roe inCampos do Jordão City (São Paulo State, Brazil) (22°44′20″S, 45°35′27″W) and the economic aspectsof its production, considering two scenarios: production in existing processing plants (scenario A)and building a plant for its production (scenario B). To estimate the net present value rates (NPV),we used different asking prices (US$ 8.50, US$ 10.00 and US$ 12.50) and interest rates (11%). Themarket research indicated a great potential for the caviar substitute, perceived as a differential ingastronomy. The results showed economic viability in scenario A, with satisfactory profitabilityand return on venture capital for the short-term at different prices. In scenario B, economic viabilityis attained at the highest price, US$ 12.50; all other simulations require careful consideration fromthe investor.(AU)

Ovas de truta arco-íris podem ser utilizadas para a confecção de sucedâneo de caviar, resultandoem produto de alto valor agregado. Este estudo objetivou avaliar o potencial de mercado doproduto no município de Campos do Jordão SP (22°44′20″S, 45°35′27″W), e os aspectoseconômicos da sua produção nas seguintes simulações: produção em estrutura de processamentopreviamente existente (simulação A), construção de estrutura específica para sua produção(simulação B), diferentes preços de venda (R$ 19,00; R$ 22,50 e R$ 28,00), e taxa de juros de 11%para estimativa do valor presente líquido (VPL). O estudo de mercado indicou grande potencialpara o sucedâneo, visto como diferencial na gastronomia. Os resultados demonstraram aviabilidade do investimento para todas as simulações da condição A, com alta rentabilidade erecuperação do investimento em curto prazo. A condição B apresentou viabilidade apenas para opreço de US$ 12.50; todas as outras simulações para esta condição requerem análise cuidadosa porparte do investidor.(AU)

Assuntos