Environmental acquisition of thiotrophic endosymbionts by deep-sea mussels of the genus bathymodiolus.
Appl Environ Microbiol
; 69(11): 6785-92, 2003 Nov.
Article
em En
| MEDLINE
| ID: mdl-14602641
ABSTRACT
Deep-sea Bathymodiolus mussels, depending on species and location, have the capacity to host sulfur-oxidizing (thiotrophic) and methanotrophic eubacteria in gill bacteriocytes, although little is known about the mussels' mode of symbiont acquisition. Previous studies of Bathymodiolus host and symbiont relationships have been based on collections of nonoverlapping species across wide-ranging geographic settings, creating an apparent model for vertical transmission. We present genetic and cytological evidence for the environmental acquisition of thiotrophic endosymbionts by vent mussels from the Mid-Atlantic Ridge. Open pit structures in cell membranes of the gill surface revealed likely sites for endocytosis of free-living bacteria. A population genetic analysis of the thiotrophic symbionts exploited a hybrid zone where two Bathymodiolus species intergrade. Northern Bathymodiolus azoricus and southern Bathymodiolus puteoserpentis possess species-specific DNA sequences that identify both their symbiont strains (internal transcribed spacer regions) and their mitochondria (ND4). However, the northern and southern symbiont-mitochondrial pairs were decoupled in the hybrid zone. Such decoupling of symbiont-mitochondrial pairs would not occur if the two elements were transmitted strictly vertically through the germ line. Taken together, these findings are consistent with an environmental source of thiotrophic symbionts in Bathymodiolus mussels, although an environmentally "leaky" system of vertical transmission could not be excluded.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Água do Mar
/
Simbiose
/
Endocitose
/
Brânquias
/
Moluscos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Appl Environ Microbiol
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Estados Unidos