ИСТИНА

Главная цель этого проекта - использовать жизненные культуры для исследования изменений в развитии кольчатых червей Siboglnidae при становлении симбиоза с внутриклеточными симбионтами.

Pogonophorans are an iconic peculiar group of deep-sea tubeworms, which according to the current phylogeny, belongs to the aberrant annelids Siboglinidae, including bone-eating worms, vestimentiferans and wood-boring worms. All siboglinids in the adult state lack a mouth and intestine and exist solely due to prokaryotic symbionts - chemoautotrophic bacteria that inhabit the cells of a special organ of symbiotrophic nutrition - trophosome. Most of the fundamental work on the structure and development of frenulate pogonophorans was made in the middle of the last century and was based on the ideas on the affinity of the pogonophorans to the deuterostomic animals. This significantly affected the scientific results: for example the radial cleavage and enterocoelic formation of the mesoderm, and division of the body (regionalization) into three parts have been described in pogonophorans, as deuterostomic animals. All these data contradict the modern interpretation of pogonophorans as representatives of annelids and require revision of the structure and development of the main ontogenetic stages from zygote to adult organisms by modern methods, including electron microscopy, laser confocal microscopy, and 3D modeling.The formation of symbiosis for pogonophorans and all other siboglinids is a crucial event for the further metamorphosis and development into an adult worm. Siboglinid larvae have a gut; they settle on a substrate with sulfide-oxidizing bacteria that penetrate the larva's body and initiate metamorphosis. It has been shown that in larvae of other siboglinids (vestimentiferans), dramatic changes occur in the body during the metamorphosis: the larval guts degrade, the mesodermal trophosome forms de novo, and all tissues and organs through which bacteria pass undergo apoptosis. In spite of the fact that pogonophorans are a sister clade to all other siboglinids what makes them a key group to research all gutless tubeworms, the developmental processes in the group remain less studied. Our knowledge of pogonophoran metamorphosis is still based on the assumptions made in late 1980s that bacteria are infected alimentary and that the trophosome develops from the intestinal wall, i.e. it has the endodermal origin. However, this contradicts the fact that the larvae of many pognophoran species do not have mouth opening, therefore, the question of the way of the bacterial infection remains open, and the organogenesis remains understudied. To study the biology and evolution of unusual frenulate pogonophorans, a key group of gutless siboglinid tubeworms, is essential to trace the processes of organogenesis in the pogonophoran larvae before and after metamorphosis, which likely is initiated by infection with prokaryotic symbionts. These studies require a preliminary analysis of the habitats and rearing the adult worms and their larvae in the laboratory. To understand the processes that occur before and after bacterial infection and that determine the organogenesis of the future adult worm, the use of modern molecular genetic technologies and electron microscopy are necessary. This knowledge will make it possible to use frenulate in the future to study specific mechanisms that control the effect of symbiotic microbiota on the ontogenesis, physiology, and immunity of their host animals.