Periodic Reporting for period 1 - CHAETA (Chaetogenesis in Annelids illumina'ted)
Okres sprawozdawczy: 2021-03-01 do 2023-02-28
One of the most characteristic features of all annelid worms (segmented worms) is their chitinous bristles, or chaetae. These chitinous, extra-cellular structures can adopt highly complex and intricate morphological structures. In the past two decades, we have accumulated great morphological understanding of the inter- and intracellular interactions that form these hard structures. This process is called chaetogenesis and it is analogous to a biological 3D printer.
One of the main objectives of CHAETA is to elucidate the molecular mechanisms underlying chaetogenesis. This is a system that harbors tremendous potential for the development of biomimetic strategies.
CHAETA aims to investigate chaetogenesis in both established annelid model systems (i.e. Capitella teleta, Platynereis dumerilii) and in the aberrant deep-sea annelid Osedax japonicus. Osedax is also known as the bone-devouring worm from whale-falls and has a unique biology. Male Osedax are minute and retain a larva-like appearance. In contrast to other annelids, their bristles develop only once and in a restricted time period. The aim of CHAETA is to take advantage of this unique condition to identify genetic markers involved in chaetogenesis. Whereas the investigation of chaetal development in model annelid species like C. teleta and P. dumerilli will allow establishing a base-line for more complex experimental designs.
One of the main objectives of CHAETA is to elucidate the molecular mechanisms underlying chaetogenesis. This is a system that harbors tremendous potential for the development of biomimetic strategies.
CHAETA aims to investigate chaetogenesis in both established annelid model systems (i.e. Capitella teleta, Platynereis dumerilii) and in the aberrant deep-sea annelid Osedax japonicus. Osedax is also known as the bone-devouring worm from whale-falls and has a unique biology. Male Osedax are minute and retain a larva-like appearance. In contrast to other annelids, their bristles develop only once and in a restricted time period. The aim of CHAETA is to take advantage of this unique condition to identify genetic markers involved in chaetogenesis. Whereas the investigation of chaetal development in model annelid species like C. teleta and P. dumerilli will allow establishing a base-line for more complex experimental designs.
The work performed during chaeta can be divided into 3 interlinked work packages:
Work package 1: Morphological investigation of chaetogenesis in Osedax japonicus
The timing of chaetogenesis in O. japonicus was determined through a detailed morphological study of development in O. japonicus larvae. Serial TEM of corresponding larval stages was conducted and the cellular interactions and patterning during chaetal formation was reconstructed.
Work package 2: Comparative transcriptomics of O. japonicus
A large and comprehensive transcriptomic dataset was generated for larvae of O.japonicus. The role of chaetoblast specific chitin synthases during chaetogenesis in O. japonicus was characterized, by analyzing their expression levels in the transcriptomes of relevant developmental stages. Chaetoblast and follicle cell specific marker genes were identified and localed using in-situ HCR experiments.
Work package 3: Chaetogenesis in model annelids.
In-depth morphological investigation of chaetae and chaetogenesis was conducted for larvae of C. teleta and in both adult and larval P. dumerilii. These provide a solid and necessary backbone for future molecular investigations in these established model systems in developmental biology.
Work package 1: Morphological investigation of chaetogenesis in Osedax japonicus
The timing of chaetogenesis in O. japonicus was determined through a detailed morphological study of development in O. japonicus larvae. Serial TEM of corresponding larval stages was conducted and the cellular interactions and patterning during chaetal formation was reconstructed.
Work package 2: Comparative transcriptomics of O. japonicus
A large and comprehensive transcriptomic dataset was generated for larvae of O.japonicus. The role of chaetoblast specific chitin synthases during chaetogenesis in O. japonicus was characterized, by analyzing their expression levels in the transcriptomes of relevant developmental stages. Chaetoblast and follicle cell specific marker genes were identified and localed using in-situ HCR experiments.
Work package 3: Chaetogenesis in model annelids.
In-depth morphological investigation of chaetae and chaetogenesis was conducted for larvae of C. teleta and in both adult and larval P. dumerilii. These provide a solid and necessary backbone for future molecular investigations in these established model systems in developmental biology.
During CHAETA the larval development of Osedax was studied in great detail. This allowed establishing a standardized morphological staging system. Coupled with the large rna-seq experiment conducted as part of CHAETA, an invaluable morphological and genetic resource was generated. This not only allows investigating chaetal formation but also opens novel research avenues in the study of Osedax. For instance, CHAETA now makes it feasible to investigate still open questions on paedomorphism of dwarf males and sex determination in Osedax.
The morphological and molecular characterization of chaetogenesis in Osedax will be published in a single publication. This study is pioneering, and will allow establishing marker genes expressed within distinct regions of the chaetal follicles (i.e. chaetoblast, follicle cells). These details are key and fundamental for understanding the molecular machinery behind chaetal formation and will allow comparative studies among other annelids and possibly other Lophotrochozoa with chaetae-like structures.
In addition to investigating chaetogenesis in Osedax. CHAETA also established the necessary morphological foundation for the experimental study of annelid chaetogenesis by focusing on existing annelid model systems. Larval chaetae of Capitella teleta and their distinct morphological differences to adult chaetae will be illustrated in a separate publication. This is necessary for future experimental and molecular work that can be conducted using the C. teleta model system. Similarly, a highly detailed study on the chaetae and chaetogenesis of Platynereis dumerilii was published. P. dumerilli is another well-established annelid model system in developmental biology. This study describes the inter- and intracellular interactions within the chaetal follicles, the chaetal topology and arrangement in both adult and larval P. dumerilii.
The morphological and molecular characterization of chaetogenesis in Osedax will be published in a single publication. This study is pioneering, and will allow establishing marker genes expressed within distinct regions of the chaetal follicles (i.e. chaetoblast, follicle cells). These details are key and fundamental for understanding the molecular machinery behind chaetal formation and will allow comparative studies among other annelids and possibly other Lophotrochozoa with chaetae-like structures.
In addition to investigating chaetogenesis in Osedax. CHAETA also established the necessary morphological foundation for the experimental study of annelid chaetogenesis by focusing on existing annelid model systems. Larval chaetae of Capitella teleta and their distinct morphological differences to adult chaetae will be illustrated in a separate publication. This is necessary for future experimental and molecular work that can be conducted using the C. teleta model system. Similarly, a highly detailed study on the chaetae and chaetogenesis of Platynereis dumerilii was published. P. dumerilli is another well-established annelid model system in developmental biology. This study describes the inter- and intracellular interactions within the chaetal follicles, the chaetal topology and arrangement in both adult and larval P. dumerilii.