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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.

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.

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ClustalX multiple protein sequence alignment of halibut predicted TnT protein; Clustal X multiple alignment of predicted protein sequences from halibut fTnThh cDNA isoforms, AfTnThh and sTnT2hh cDNAs. Shaded areas represent sequence similarity. The N-terminal hypervariable region and Tropomyosin- and Troponin I-binding regions are indicated.
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Figure 1: ClustalX multiple protein sequence alignment of halibut predicted TnT protein; Clustal X multiple alignment of predicted protein sequences from halibut fTnThh cDNA isoforms, AfTnThh and sTnT2hh cDNAs. Shaded areas represent sequence similarity. The N-terminal hypervariable region and Tropomyosin- and Troponin I-binding regions are indicated.

Mentions: Five cDNAs corresponding to different skeletal muscle TnT genes (Fig. 1) were isolated from a cDNA library of metamorphosing halibut larvae. In tBLASTx analysis [27] against the GeneBank database, three cDNAs gave a highly significant match with teleost, fTnT genes. From the analysis it was determined that the fTnThh cDNAs isolated correspond to a putative embryonic/larval halibut fTnT (denominated efTnThh; DQ680173) and two different adult isoforms (denominated fTnThh-1, DQ680174, and fTnThh-2, DQ680175). The efTnThh cDNA is a full-length clone with 965 nucleotides (nt) and encodes a 286 amino acids (aa) protein from nt 62 to 919. The size of the deduced protein is 34.6 kDa and the predicted pI is 5.27 (Fig. 1)[28]. The fTnThh-1 isoform is a 752 bp cDNA which encodes a protein of 232 aa from nt 22 to 717 (Fig. 1). The deduced fTnThh-1 protein has a predicted molecular weight of 27.89 kDa and a pI of 9.42 [28]. The cDNA of the third isoform, denominated fTnThh-2, is 1,020 bp long and encodes a putative protein of 229 aa from nt 70 to 756 (Fig. 1). The predicted molecular weight and pI for the fTnThh-2 protein isoform is respectively 27.5 kDa and 9.55 [28].


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)

ClustalX multiple protein sequence alignment of halibut predicted TnT protein; Clustal X multiple alignment of predicted protein sequences from halibut fTnThh cDNA isoforms, AfTnThh and sTnT2hh cDNAs. Shaded areas represent sequence similarity. The N-terminal hypervariable region and Tropomyosin- and Troponin I-binding regions are indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: ClustalX multiple protein sequence alignment of halibut predicted TnT protein; Clustal X multiple alignment of predicted protein sequences from halibut fTnThh cDNA isoforms, AfTnThh and sTnT2hh cDNAs. Shaded areas represent sequence similarity. The N-terminal hypervariable region and Tropomyosin- and Troponin I-binding regions are indicated.
Mentions: Five cDNAs corresponding to different skeletal muscle TnT genes (Fig. 1) were isolated from a cDNA library of metamorphosing halibut larvae. In tBLASTx analysis [27] against the GeneBank database, three cDNAs gave a highly significant match with teleost, fTnT genes. From the analysis it was determined that the fTnThh cDNAs isolated correspond to a putative embryonic/larval halibut fTnT (denominated efTnThh; DQ680173) and two different adult isoforms (denominated fTnThh-1, DQ680174, and fTnThh-2, DQ680175). The efTnThh cDNA is a full-length clone with 965 nucleotides (nt) and encodes a 286 amino acids (aa) protein from nt 62 to 919. The size of the deduced protein is 34.6 kDa and the predicted pI is 5.27 (Fig. 1)[28]. The fTnThh-1 isoform is a 752 bp cDNA which encodes a protein of 232 aa from nt 22 to 717 (Fig. 1). The deduced fTnThh-1 protein has a predicted molecular weight of 27.89 kDa and a pI of 9.42 [28]. The cDNA of the third isoform, denominated fTnThh-2, is 1,020 bp long and encodes a putative protein of 229 aa from nt 70 to 756 (Fig. 1). The predicted molecular weight and pI for the fTnThh-2 protein isoform is respectively 27.5 kDa and 9.55 [28].

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