Browsing by Author "Sousa, V."
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- Incubation temperature induces changes in muscle cellularity and gene expression in Senegalese sole (Solea senegalensis)Publication . Campos, C.; Valente, L. M. P.; Conceição, L. E. C.; Engrola, S.; Sousa, V.; Rocha, E.; Fernandes, J. M. O.Fertilised eggs of Senegalese sole were incubated at 15, 18 or 21 °C, and after hatching all larvae were reared at 21 °C until 30 days post-hatch. By this point larvae from the 18 or 21 °C temperature groups had 11 and 9% more muscle fibres than those from 15 °C, respectively. Hyperplastic growth during metamorphosis was higher in larvae from 18 °C. Embryonic temperature induced gene expression changes, albeit with a variable pattern throughout development. Myf5, myod2, myHC and fst mRNA levels were significantly higher at several stages prior to hatching in embryos incubated at 21 °C, whereas hsp90AB and hsp70 transcripts were present at higher levels in the 15 °C group. Myf5, myod1, myod2, pax7, myog, fst, igf-II, igf1r, hsp90AA and hsp90AB were expressed at higher levels during early development, particularly during somitogenesis. In contrast, mrf4, myHC, mylc2, igf-I, mstn1 and hsp70 were up-regulated at later stages of larval development, namely during and after metamorphosis. This study is the first example of thermal plasticity of myogenesis with prolonged effect in a flatfish.
- Thermal conditions during larval pelagic phase influence subsequent somatic growth of Senegalese sole by modulating gene expression and muscle growth dynamicsPublication . Campos, C.; Fernandes, J. M. O.; Conceição, L. E. C.; Engrola, S.; Sousa, V.; Valente, L. M. P.In the present study, Senegalese sole eggs incubated at 20 °C were reared at three different temperatures (15 °C, 18 °C or 21 °C) during the pelagic phase, and then transferred to a common temperature (20 °C) from benthic stage until 100 days post-hatch (dph). Somatic growth, fast muscle cellularity and expression of 15 growth-related genes were compared at the same developmental stage for each temperature (pre-metamorphic larvae, metamorphic larvae, post-metamorphic larvae) and at 83 dph and 100 dph early juveniles. During pre-metamorphosis and metamorphosis, larvae from 21 °C weighed significantly more than those reared at 18 °C or 15 °C (P < 0.001). Relative growth rate (RGR) of pelagic larvae and survival of newly-settled larvae were also higher at 21 °C (P < 0.05). Furthermore, an increase in muscle growth towards the highest temperatures was observed concomitantly with an increase in gene expression, namely myogenic regulatory factors (MRFs), myosins, igf-I and fgf6. After transfer to a common temperature (20 °C), the 15 °C group initiated a process of compensatory growth, inverting relative growth rate values that became the highest, particularly between 83 dph and 100 dph (P < 0.05). This increased growth effort in the 15 °C group was accompanied by an up-regulation of gene expression in fast muscle, particularly in the 83 dph juveniles. Mrf4 and myHC were up-regulated at 15 °C and positive correlations with growth were also found for myog or pax7 (P < 0.05). In contrast, mstn1 was down-regulated at 15 °C (P < 0.05), suggesting a boost in muscle growth. By 100 dph, the 15 °C group had already reached the same weight as the 18 °C and the same length as the 21 °C ones. At this age, the 18 °C juveniles had the largest mean muscle fibre diameter (P < 0.001), and thus fibre hypertrophy seems to be a major growth mechanism relatively to the other groups. Our work shows that temperature during pelagic phase greatly influences the growth trajectory of Senegalese sole juveniles.
- Thermal plasticity of muscle cellularity and gene expression in Senegalese sole (Solea senegalensis)Publication . Campos, C.; Valente, L. M. P.; Conceição, L. E. C.; Engrola, S.; Sousa, V.; Rocha, E.; Gavaia, Paulo J.; Fernandes, J. M. O.Temperature-induced responses at the level of muscle growth potential have been observed in teleost fish species, concomitantly with gene expression changes (Johnston and Hall 2004). Incubation temperature has been demonstrated to influence the muscle cellularity at hatch and during larval development, and these effects are highly species-specific. Changes in the relative timing and expression level of myogenic genes were found to be related with thermal plasticity of muscle phenotype (Fernandes, Mackenzie et al. 2006). The eggs of the flatfish Senegalese sole (Solea senegalensis) in aquaculture conditions are normally incubated within the 16-20ºC range, but influence of temperature on muscle cellularity and expression of growth-related genes is unknown. Understanding these effects may contribute to improve growth conditions and juvenile production.