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Troponin T isoform expression is modulated during Atlantic halibut metamorphosis.

Campinho MA, Silva N, Nowell MA, Llewellyn L, Sweeney GE, Power DM - BMC Dev. Biol. (2007)

Bottom Line: In contrast, expression of red muscle specific genes, AfTnT and sTnT2, did not change during natural metamorphosis or after T4 treatment.Muscle organisation in halibut remains symmetrical even after metamorphosis suggesting TH driven changes are associated with molecular adaptations.We hypothesize that species specific differences in TnT gene expression in teleosts underlies different larval muscle developmental programs which better adapts them to the specific ecological constraints.

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Affiliation: CCMAR, FERN, Universidade do Algarve, Campus de Gambelas, Faro, Portugal. macampin@ualg.pt <macampin@ualg.pt>

ABSTRACT

Background: Flatfish metamorphosis is a thyroid hormone (TH) driven process which leads to a dramatic change from a symmetrical larva to an asymmetrical juvenile. The effect of THs on muscle and in particular muscle sarcomer protein genes is largely unexplored in fish. The change in Troponin T (TnT), a pivotal protein in the assembly of skeletal muscles sarcomeres and a modulator of calcium driven muscle contraction, during flatfish metamophosis is studied.

Results: In the present study five cDNAs for halibut TnT genes were cloned; three were splice variants arising from a single fast TnT (fTnT) gene; a fourth encoded a novel teleost specific fTnT-like cDNA (AfTnT) expressed exclusively in slow muscle and the fifth encoded the teleost specific sTnT2. THs modified the expression of halibut fTnT isoforms which changed from predominantly basic to acidic isoforms during natural and T4 induced metamorphosis. In contrast, expression of red muscle specific genes, AfTnT and sTnT2, did not change during natural metamorphosis or after T4 treatment. Prior to and after metamorphosis no change in the dorso-ventral symmetry or temporal-spatial expression pattern of TnT genes and muscle fibre organization occurred in halibut musculature.

Conclusion: Muscle organisation in halibut remains symmetrical even after metamorphosis suggesting TH driven changes are associated with molecular adaptations. We hypothesize that species specific differences in TnT gene expression in teleosts underlies different larval muscle developmental programs which better adapts them to the specific ecological constraints.

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Halibut whole-body T4 levels during metamorphosis; Change in whole-animal T4 content (pg/mg) during halibut metamorphosis. *- No significant statistical difference (HSD, p > 0.05). + and # denote significant statistical differences from all other time points (HSD, p < 0.05).
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Figure 10: Halibut whole-body T4 levels during metamorphosis; Change in whole-animal T4 content (pg/mg) during halibut metamorphosis. *- No significant statistical difference (HSD, p > 0.05). + and # denote significant statistical differences from all other time points (HSD, p < 0.05).

Mentions: At the beginning of metamorphosis and up until the beginning of climax (stg 8), T4 levels remain low with no significant differences observed between stages 5, 6 and 8 (HSM, p > 0.05; Fig. 10). In fact in larvae at the beginning of metamorphosis (stg 7) T4 levels are lower than in pre-metamorphic larvae (stg 5, HSD, p < 0.05). At the climax of metamorphosis (stg 9), whole-body T4 content increases about 3-fold in relation to all the previous stages (HSM, p < 0.005, Fig. 10). In post-metamorphic juveniles (stg 10) T4 levels continue high and, although not significantly different from stage 9, they are significantly higher than all other preceding stages (stg 5 to 8, HSM, p < 0.001; Fig. 10).


Troponin T isoform expression is modulated during Atlantic halibut metamorphosis.

Campinho MA, Silva N, Nowell MA, Llewellyn L, Sweeney GE, Power DM - BMC Dev. Biol. (2007)

Halibut whole-body T4 levels during metamorphosis; Change in whole-animal T4 content (pg/mg) during halibut metamorphosis. *- No significant statistical difference (HSD, p > 0.05). + and # denote significant statistical differences from all other time points (HSD, p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1919359&req=5

Figure 10: Halibut whole-body T4 levels during metamorphosis; Change in whole-animal T4 content (pg/mg) during halibut metamorphosis. *- No significant statistical difference (HSD, p > 0.05). + and # denote significant statistical differences from all other time points (HSD, p < 0.05).
Mentions: At the beginning of metamorphosis and up until the beginning of climax (stg 8), T4 levels remain low with no significant differences observed between stages 5, 6 and 8 (HSM, p > 0.05; Fig. 10). In fact in larvae at the beginning of metamorphosis (stg 7) T4 levels are lower than in pre-metamorphic larvae (stg 5, HSD, p < 0.05). At the climax of metamorphosis (stg 9), whole-body T4 content increases about 3-fold in relation to all the previous stages (HSM, p < 0.005, Fig. 10). In post-metamorphic juveniles (stg 10) T4 levels continue high and, although not significantly different from stage 9, they are significantly higher than all other preceding stages (stg 5 to 8, HSM, p < 0.001; Fig. 10).

Bottom Line: In contrast, expression of red muscle specific genes, AfTnT and sTnT2, did not change during natural metamorphosis or after T4 treatment.Muscle organisation in halibut remains symmetrical even after metamorphosis suggesting TH driven changes are associated with molecular adaptations.We hypothesize that species specific differences in TnT gene expression in teleosts underlies different larval muscle developmental programs which better adapts them to the specific ecological constraints.

View Article: PubMed Central - HTML - PubMed

Affiliation: CCMAR, FERN, Universidade do Algarve, Campus de Gambelas, Faro, Portugal. macampin@ualg.pt <macampin@ualg.pt>

ABSTRACT

Background: Flatfish metamorphosis is a thyroid hormone (TH) driven process which leads to a dramatic change from a symmetrical larva to an asymmetrical juvenile. The effect of THs on muscle and in particular muscle sarcomer protein genes is largely unexplored in fish. The change in Troponin T (TnT), a pivotal protein in the assembly of skeletal muscles sarcomeres and a modulator of calcium driven muscle contraction, during flatfish metamophosis is studied.

Results: In the present study five cDNAs for halibut TnT genes were cloned; three were splice variants arising from a single fast TnT (fTnT) gene; a fourth encoded a novel teleost specific fTnT-like cDNA (AfTnT) expressed exclusively in slow muscle and the fifth encoded the teleost specific sTnT2. THs modified the expression of halibut fTnT isoforms which changed from predominantly basic to acidic isoforms during natural and T4 induced metamorphosis. In contrast, expression of red muscle specific genes, AfTnT and sTnT2, did not change during natural metamorphosis or after T4 treatment. Prior to and after metamorphosis no change in the dorso-ventral symmetry or temporal-spatial expression pattern of TnT genes and muscle fibre organization occurred in halibut musculature.

Conclusion: Muscle organisation in halibut remains symmetrical even after metamorphosis suggesting TH driven changes are associated with molecular adaptations. We hypothesize that species specific differences in TnT gene expression in teleosts underlies different larval muscle developmental programs which better adapts them to the specific ecological constraints.

Show MeSH
Related in: MedlinePlus