Effects of direct development on the neuromuscular formation in an annelid

Main area:Marine biology
Target group:Biology
Educational level:Masters, Bachelor
Project description:

The field of evodevo tries to understand the interactions between evolution and development, which lead to the respective organism. Amongst others, some of the questions deal with how conserved certain morphological traits are (e.g. nervous system architecture, developmental sequence of the formation of organ systems), and what causes differences in the adults. An example to study the morphology and the development of organ systems are the closely related Dinophilidae, which are in culture at the Marine Biological Section in Copenhagen and display a variety of life styles (rapid life cycle vs. prolonged encystment stage), behaviours (e.g. courtship behaviour vs. mating with sibling inside the cocoon) and complexities (e.g. 68 cells in the entire organism to several hundred in the copulatory region alone). A recent study focussing on the two morphotypes of Dinophilus analysed the morphogenesis of the nervous and muscular system as well as the overall ciliation patterns, unveiling that the smaller D. gyrociliatus possibly resembles a juvenile stage of the larger D. taeniatus. Trilobodrilus axi represents the second genus of the family Dinophilidae, and although its morphology resembles that of the two dinophilids to a high degree, the arrangement of the commissures in the brain and the ventral nervous system varies, making homology assignments impossible.

The overall objectives of this project are the analysis of common patterns in the development of these annelids, the assessment of the homology of neural elements such as commissures by comparing the patterns between T. axi and the two previously mapped Dinophilus-species, and the documentation of possible affects of the different complexity and life styles on the developmental patterns by understanding and mapping the morphogenesis of the nervous system, musculature, and ciliation patterns of T. axi. The project includes the collection of animals in the field (from Sylt, Germany), rearing them in the laboratory and preparing them for immunohistochemical studies and advanced bioimaging by CLSM. The generation of a developmental atlas of the nervous system, ciliation patterns, and musculature will extend our current knowledge of this family’s development, thereby establishing a detailed resource to correlate morphological and developmental patterns across three species and subsequently identify common traits vs. species- or lineage-specific modifications.

Methods used:Microscopy (light microscopy, confocal laser scanning microscopy), immunohistochemistry, 3D-reconstruction
Supervisor(s):  Katrine Worsaae