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Metallothioneins in the hydrothermal modioles  : Bathymodiolus thermophilus et Bathymodiolus azoricus

Metallothioneins in the hydrothermal modioles  : Bathymodiolus thermophilus et Bathymodiolus azoricus. Yann HARDIVILLIER. Université du Maine (Le Mans – France). Metallothioneins in Bathymodiolus sp. Introduction. Bathymodiolus sp. The model:. Phylum: Mollusca Class: Bivalvia

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Metallothioneins in the hydrothermal modioles  : Bathymodiolus thermophilus et Bathymodiolus azoricus

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  1. Metallothioneins in the hydrothermal modioles  : Bathymodiolus thermophilus et Bathymodiolus azoricus Yann HARDIVILLIER Université du Maine (Le Mans – France)

  2. Metallothioneins in Bathymodiolus sp. Introduction Bathymodiolus sp. The model: Phylum: Mollusca Class: Bivalvia Family: Mytilidae Subfamily: Bathymodiolinae • 15 Species • Live around vents • 4-30°C • High metal concentrations B. azoricus Cosel & Comtet, 1999 B. thermophilus Kenk & Wilson, 1985 Mechanisms ? Metallothioneins

  3. Metallothioneins in Bathymodiolus sp. • → In the edible mussel, Mytilus edulis • MT-10 = Essential metal homeostasis • MT-20= Induction by Cd Introduction Metallothioneins • Low molecular weight proteins • Ubiquist • High Cysteine content • Metal Storage Comparison between metallothioneins in coastal (Mytilus)and hydrothermal (Bathymodiolus) bivalves Adaptations to the hydrothermal environment ?

  4. Metallothioneins in Bathymodiolus sp. • 1 sequence in B. azoricus (AJ969240) • 2 sequences in B. thermophilus (AJ577128 and AJ577129) • (98 % homology) High interspecific homology (93 %), Conservation of the cysteines position Metallothioneins gene caractérisation in Bathymodiolus sp. Caracterisation of genomic sequences of MT-10 genes in Bathymodiolus sp. • Isolation of intronless sequences in each species • (as in Mytilus edulisLeignel et al, 2004 and Crassostrea gigasTanguy, personal Communication)

  5. Metallothioneins in Bathymodiolus sp. High interspecific homology (94 %), Conservation of the cysteine position Metallothioneins gene caractérisation in Bathymodiolus sp. Caracterisation of coding sequences (cDNA) of MT-10 genes in Bathymodiolus sp. • 1 sequence in B. thermophilus (AJ517188) • 3 sequences in B. azoricus (AJ630215, AJ630216 et AJ630217) (99 % homology)

  6. Metallothioneins in Bathymodiolus sp. Metallothioneins gene caracterisation in Bathymodiolus sp. Comparison of coding sequences (cDNA) MT-10genes between Bathymodiolus sp. and Mytilus edulis • Conclusions : • High homology between B. azoricus andB. thermophilus • High homology between Bathymodiolusand Mytilus

  7. Metallothioneins in Bathymodiolus sp. • 1 sequence in B. azoricus (AJ630218) • 1 sequence in B. thermophilus (AJ630219) Metallothioneins gene caracterisation in Bathymodiolus sp. Caracterisation of coding sequences (cDNA) of MT-20 genes in Bathymodiolus sp. • Isolation identical sequences in both species • Conclusions : • Highhomologies between MT-20 genes but lesserthan for MT-10 genes. • Conservation of the cysteine position

  8. Metallothioneins in Bathymodiolus sp. Outgroup MTs Mytilidae Metallothioneins gene caracterisation in Bathymodiolus sp. Phyletic analysis of metallothionein genes • Conclusions: • Mytilidae vs Ostreidae • MT-10 vs MT-20 • Bathymodiolus / Mytilus ~ NJ, 1000 replicates

  9. Metallothioneins in Bathymodiolus sp. Metallothionein expression in Bathymodiolus sp. Analyses of metallothionein gene expression and metallothionein content in Bathymodiolus sp. Bathymodiolus sp. MT10-mRNA and MT20-mRNA MTs content ISOMER, Nantes

  10. Metallothioneins in Bathymodiolus sp. Metallothionein expression in Bathymodiolus sp. Metallothioneins expression in Bathymodiolus azoricus (Cosel & Comtet, 1999) Lucky Strike Modioles exposition : Influence of pressure and Cadmium IPOCAMP: 170 atm 100 µg/L 2x12h ; 24h ; 2x24h

  11. Metallothioneins in Bathymodiolus sp. B M MT-20 / Histone-4 - + - + Metallothionein expression in Bathymodiolus sp. Metallothioneins Gene Expression in Bathymodiolus azoricus 2 x 12 h • Conclusions: • NO induction for both isoforms • Weak standard deviations • Gills vs Mantle : Ǿ • Actin-1 = Histone-4 • 28S rRNAr? • (intraspecific Variability of transcriptionnal activity) • MT-20 = 3x MT-10 (≠in M. edulis, Lemoine et al, 2000) G B M G B M B M G MT-10 / Actin-1 MT-10 / Histone-4 MT-10 / 28S ( ) Similar results for the 3 exposition times (2 x 12h, 24h et 2 x 24h) - + - + - + - + - + - + B M G G B M G MT-20 / Actin-1 MT-20 / 28S - + - + - + - +

  12. Metallothioneins in Bathymodiolus sp. Gills Mantle Gills Gills Mantle Mantle - + - + - + - + - + - + Metallothionein expression in Bathymodiolus sp. Metallothionein content inBathymodiolus azoricus 2 x 12 h 24 h 2 x 24 h • Conclusions: • No induction of metallothionein synthesis • Weak standard deviations • Gills > Mantle ? (post transcriptionnal control) • [MT] B.azo> [MT] coastal bivalves (from Géret, 2000)

  13. Metallothioneins in Bathymodiolus sp. Metallothionein expression in Bathymodiolus sp. Metallothioneins Expression in Bathymodiolus thermophilus (Kenk & Wilson, 1985) Modioles exposition : Influence of metals Similar Results : MT-mRNAs : No induction to metals Gills=Mantle MT-20 = 3x MT-10 MTs : No induction to Cd but induction to Ag Gills>Mantle [MTs] B. thermophilus > Coastal bivalves  Post transcriptionnal control Biovent (9°N) Atmospheric Pressure 42h

  14. Metallothioneins in Bathymodiolus sp. Conclusions Conclusions • Both types of metallothioneins (MT-10 et MT-20) found in M. edulis were isolated in Bathymodiolus sp. • High homology between MT sequences of B. azoricus et B. thermophilus, and betweenBathymodiolus and Mytilus • Particularism of metallothionein genes in Bathymodiolus sp. (no MT-mRNA induction and [MT-20 mRNA]=3x[MT-10 mRNA]) • High metallothionein content comparatively to coastal bivalves • Post transcriptionnal control of metallothionein genes ? • Both types of metallothioneins (MT-10 et MT-20) found in M. edulis were isolated in Bathymodiolus sp. • High homology between MT sequences of B. azoricus et B. thermophilus, and betweenBathymodiolus and Mytilus • Particularism of metallothionein genes in Bathymodiolus sp. (no MT-mRNA induction and [MT-20 mRNA]=3x[MT-10 mRNA]) • High metallothionein content comparatively to coastal bivalves • Post transcriptionnal control of metallothionein genes ?

  15. Metallothioneins in Bathymodiolus sp. Aknowledgments The team: Dr Françoise DENIS Dr Vincent LEIGNEL Pr Marc LAULIER Pr Benoît CHENAIS Dr Richard COSSON

  16. Metallothioneins in Bathymodiolus sp. Aknowledgments Thank you for your attention

  17. World champions !!! France

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