Dataset Information

Swimming exercise to control precocious maturation in male seabass (Dicentrarchus labrax).

ABSTRACT: BACKGROUND:Male European seabass, already predominant (~?70%) in cultured stocks, show a high incidence (20-30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we aimed at investigating the effects of sustained swimming on reproductive development in seabass males during the first year of life in order to determine if swimming could potentially reduce precocious sexual maturation. METHODS:Pre-pubertal seabass (3.91?±?0.22 g of body weight (BW)) were subjected to a 10 week swimming regime at their optimal swimming speed (Uopt) in an oval-shaped Brett-type flume or kept at rest during this period. Using Blazka-type swim tunnels, Uopt was determined three times during the course of the experiment: 0.66 m s-?1 at 19?±?1 g BW, 10.2?±?0.2 cm of standard length (SL) (week 1); 0.69 m s-?1 at 38?±?3 g BW, 12.7?±?0.3 cm SL (week 5), and also 0.69 m s-?1 at 77?±?7 g BW, 15.7?±?0.5 cm SL (week 9). Every 2 weeks, size and gonadal weight were monitored in the exercised (N?=?15) and non-exercised fish (N?=?15). After 10 weeks, exercised and non-exercised males were sampled to determine plasma 11-ketotestosterone levels, testicular mRNA expression levels of genes involved in steroidogenesis and gametogenesis by qPCR, as well as the relative abundance of germ cells representing the different spermatogenic stages by histological examination. RESULTS:Our results indicate that sustained swimming exercise at Uopt delays testicular development in male European seabass as evidenced by decreased gonado-somatic index, slower progression of testicular development and by reduced mRNA expression levels of follicle stimulating hormone receptor (fshR), 3-beta-hydroxysteroid dehydrogenase (3?hsd), 11-beta hydroxysteroid dehydrogenase (11?hsd), estrogen receptor-beta (er?2), anti-mullerian hormone (amh), structural maintenance of chromosomes protein 1B (smc1?), inhibin beta A (inhba) and gonado-somal derived factor 1 (gsdf1) in exercised males as compared with the non-exercised males. CONCLUSIONS:Swimming exercise may represent a natural and non-invasive tool to reduce the incidence of sexually precocious males in seabass aquaculture.

SUBMITTER: Graziano M

PROVIDER: S-EPMC5897932 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Swimming exercise to control precocious maturation in male seabass (Dicentrarchus labrax).

Graziano Marco M Benito Raul R Planas Josep V JV Palstra Arjan P AP

BMC developmental biology 20180412 1

<h4>Background</h4>Male European seabass, already predominant (~ 70%) in cultured stocks, show a high incidence (20-30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we aimed at investigating the effects of sustained swimming on reproductive development in seabass males during the first year of life in order to d ...[more]

PMID: 29649968

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Project description:Methionine presents a pivotal role in the regulation of many cellular events with crucial impact on the immune system, such as in processes involved in the control of inflammation and polyamines synthesis. Accordingly, the present study aimed to assess the modulatory effects of dietary methionine on the European seabass (Dicentrarchus labrax) immune status, inflammatory response and disease resistance to Photobacterium damselae subsp. piscicida (Phdp). For this purpose, fish were randomly distributed in three independent groups (three replicates per group) and each was fed the corresponding diet: a control diet (CTRL) formulated to meet the established amino acid requirements for the species; a diet supplemented with methionine at 0.5% of feed weight relative to the CTRL diet (8.2% of methionine concentration above CTRL); and one supplemented with methionine at 1% of feed weight to the CTRL diet (11.8% of methionine concentration above CTRL). To evaluate the immune status of fish fed with each of the diets before being submitted to bacterial infection fish were sampled from each group at 2 and 4 weeks after the beginning of feeding. Non-sampled fish were injected intraperitoneally with Phdp (5 × 103 cfu/fish) at 4 weeks after initiation of feeding and the inflammatory response (at 4, 24, and 48 h post-infection) and survival (lasting 21 days post-infection) evaluated. Fish hematological profile, peripheral cell dynamics, plasma humoral immune parameters, leucocyte migration to the inflammatory focus and head-kidney gene expression were evaluated. Results show that methionine dietary supplementation improves seabass cellular immune status without evidence of activation of pro-inflammatory mechanisms. Additionally, the observed enhanced immune status provided by methionine supplementation translated into an improved immune response to infection, as higher cellular differentiation/proliferation and recruitment to the inflammatory focus, improved plasma humoral immune parameters and modulation of key immune-related genes was observed. Lastly, after a bacterial challenge, higher survival was observed in fish fed supplemented diets, ultimately corroborating the positive effect of methionine administration for 4 weeks in the cellular immune status.

Dataset Information

Swimming exercise to control precocious maturation in male seabass (Dicentrarchus labrax).

Publications

Swimming exercise to control precocious maturation in male seabass (Dicentrarchus labrax).

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