Generation of a reference transcriptome for evaluating rainbow trout responses to various stressors

<p>Abstract</p> <p>Background</p> <p>Fish under intensive culture conditions are exposed to a variety of acute and chronic stressors, including high rearing densities, sub-optimal water quality, and severe thermal fluctuations. Such stressors are inherent in aquaculture production and can induce physiological responses with adverse effects on traits important to producers and consumers, including those associated with growth, nutrition, reproduction, immune response, and fillet quality. Understanding and monitoring the biological mechanisms underlying stress responses will facilitate alleviating their negative effects through selective breeding and changes in management practices, resulting in improved animal welfare and production efficiency.</p> <p>Results</p> <p>Physiological responses to five treatments associated with stress were characterized by measuring plasma lysozyme activity, glucose, lactate, chloride, and cortisol concentrations, in addition to stress-associated transcripts by quantitative PCR. Results indicate that the fish had significant stressor-specific changes in their physiological conditions. Sequencing of a pooled normalized transcriptome library created from gill, brain, liver, spleen, kidney and muscle RNA of control and stressed fish produced 3,160,306 expressed sequence tags which were assembled and annotated. SNP discovery resulted in identification of ~58,000 putative single nucleotide polymorphisms including 24,479 which were predicted to fall within exons. Of these, 4907 were predicted to occupy the first position of a codon and 4110 the second, increasing the probability to impact amino acid sequence variation and potentially gene function.</p> <p>Conclusion</p> <p>We have generated and characterized a reference transcriptome for rainbow trout that represents multiple tissues responding to multiple stressors common to aquaculture production environments. This resource compliments existing public transcriptome data and will facilitate approaches aiming to evaluate gene expression associated with stress in this species.</p

The effect of stocking density and repeated handling on\ud the growth of juvenile mulloway, Argyrosomus japonicus\ud (Temminck & Schlegel 1843)

The effect of stocking density on the growth of mulloway, Argyrosomus japonicus, was tested with 17 g fish stocked at 4.08, 8.16, or 16.32 kg m−3 in 50 l aquaria. Weight checks were carried out every 2 weeks to track performance. Each density treatment was also compared to a nonhandled control group to establish if handling during weight checks influenced the growth of mulloway. Mulloway performed poorly at the lowest density and, under the current experiment conditions, growth did not appear to be negatively affected by regular handling

Influência da concentração de benzocaína e do comprimento dos peixes na anestesia e na recuperação de tilápias-do-nilo Effect of benzocaine concentration and fish size on anesthesia and recovery in Nile tilapia

Com o objetivo de avaliar a influência da concentração de benzocaína na indução e recuperação da anestesia em tilápias-do-nilo (Oreochromis niloticus) de diferentes comprimentos, desenvolveu-se um experimento em blocos casualizados, em esquema fatorial 4 × 4, composto de quatro comprimentos de peixes (6; 10; 14 e 18 cm de comprimento total) e quatro concentrações de benzocaína (60; 120; 180 e 240 mg por litro de água). A indução e a recuperação da anestesia foram divididas em três estágios, de acordo com o comportamento dos peixes sob efeito do anestésico, registrando-se o tempo de permanência em cada estágio. As diferenças de comprimento não influenciaram de forma significativa os tempos de anestesia e recuperação. Regressões lineares com plateau foram geradas para estimar o ponto em que o aumento da dose deixou de ter efeito. Durante a indução à anestesia, o plateau ocorreu na concentração de 132 mg/L e o tempo estimado para atingir a sedação total (estágio 3) foi de 86 segundos. Para permanência do peixe sob sedação total, é necessária concentração de benzocaína de 190 mg/L e o tempo estimado de permanência neste estágio é de 91,1 segundos. Concentrações superiores a 190 mg de benzocaína por litro de água não produzem efeitos que justifiquem seu emprego.<br>To evaluate the influence of benzocaine concentration on the induction and recovery from anesthesia in different sized Nile tilapia (Oreochromis niloticus), it was developed a random block experiment design in 4 × 4 factorial consisted of four fish lengths (6; 10; 14 and 18 cm total lenght) and four benzocaine concentrations (60; 120; 180 and 240 mg of benzocaine per liter of water). The induction and the recovery from anesthesia were divided in three stages based on the behavior of the fishes under anesthetic effect. The time spent in each stage was recorded. Differences in length did not affect significantly the anesthesia and recovery time. Linear plateu regressions were generated to estimate the point which increases on anesthetic doses does not imply in further effects. During the anesthesia induction, the plateu occurred in concentration time of 132 mg/L, and estimated time of 86 seconds would be necessary to achieve the complete sedation (stage 3). For permanence of the fish under total sedation, it is needed 190 g/L benzocaine and estimated time of permanence in this stage is 91.1 seconds. Benzocaine concentrations above 190 mg/L do not produce any additional effects that justify its use

Eugenol como anestésico para a tilápia-do-nilo Eugenol as an anesthetic for Nile tilapia

O objetivo deste trabalho foi avaliar o eugenol como anestésico para a tilápia-do-nilo. Para a concentração ideal, foram avaliados seis tratamentos (50, 75, 100, 150, 200 e 250 mg L-1), com dez peixes por tratamento, anestesiados individualmente, acompanhados durante a indução e recuperação. A toxicidade foi estimada pela submissão de 210 peixes a 7 concentrações de eugenol (50, 75, 100, 150, 200, 250, 300 mg L-1), durante 600 s e, para a margem de segurança, 120 peixes foram submetidos a 75 mg L-1 durante cinco intervalos de tempo (600, 1.200, 1.800 e 2.400 s). As concentrações eficientes foram 50 e 75 mg L-1. Os valores de toxicidade letal (CL), aos 600 s, foram: CL01, 81,97 mg L-1; CL50, 184,26 mg L-1; e CL99, 286,55 mg L-1; e os tempos de concentrações letais (TCL) foram: TCL01, 566,97 s; TCL50, 1.611,66 s; e TCL99, 2.656,34 s. Concluiu-se que 75 mg L-1 são suficientes para a anestesia profunda de curta duração, com margem de segurança de 484,27 s, e 50 mg L-1 para longos períodos (600 s). A maior concentração terapêutica do eugenol custa R$0,065 por litro de água. A eutanásia pode ser realizada com 286,55 mg L-1 durante 600 s.<br>The objective of this work was to evaluate eugenol as anesthetic for Nile tilápia. For the best concentration of the anaesthetic, six treatments (50, 75, 100, 150, 200, and 250 mg L-1) were evaluated, with ten fishes per treatment, anesthetised individually and monitored during the induction and recovery. Toxicity was estimated in 210 fish submitted to seven eugenol concentrations (50, 75, 100, 150, 200, 250, and 300 mg L-1) for 600 s; and for safety margin, 120 fish were submitted to 75 mg L-1 for five time intervals (600, 1,200, 1,800, and 2,400 s). The effective concentrations were 50 and 75 mg L-1. Lethal concentration (LC) values for 600 s were: LC01 81.97 mg L-1, LC50 184.26 mg L-1, and LC99 286.55 mg L-1. Times of lethal concentration (TLC) were TLC01 566.97 s, TLC50 1,611.66 s, and TLC99 2,656.34 s. For fast deep anesthesia, 75 mg L-1 of eugenol is recommended, with a safety margin of 484,27 s; for long period anesthesia (600 s) 50 mg L-1 were recommended. The higher therapeutic concentration costs R$ 0.065 per liter. Eugenol was effective for euthanasia at 286.55 mg L-1 for 600 s

Diplotaxis glabrimargo (dorsal)

Paratipo de Diplotaxis glabrimargo Vaurie y Cazie