Untersuchungen ursprünglicher molekularer Mechanismen der Keimbahnspezifizierung in Bilateria mit Hilfe der Spinne Achaearanea tepidariorum
Zusammenfassung der Projektergebnisse
Studies in vertebrate and invertebrate model organisms on the molecular basis of germ cell specification have revealed that metazoans can specify their germline either early in development by maternally transmitted cytoplasmic factors (inheritance), or later in development by signalling factors from neighbouring tissues (induction). The arthropods are the most speciose animal phylum, and are one of the phyla whose members appear to exhibit both induction and inheritance modes of germline specification. However, to date there have been no functional studies of conserved germline genes in species of the most basally branching arthropod clade, the chelicerates (which includes spiders, scorpions, and horseshoe crabs). Here I present the first such study by using molecular and functional tools to examine germline development in the common house spider Parasteatoda (formerly Achaearanea) tepidariorum. I used transcript and protein expression patterns of the conserved germline marker genes vasa and piwi to show that primordial germ cells (PGCs) in the spider arise during late embryogenesis. Neither Pt-vasa nor Pt-piwi gene products are localized asymmetrically to any embryonic region before PGCs emerge as paired segmental clusters in opisthosomal segments 2-6 at late germ band stages. Functional studies of the role of Pt-vasa revealed that zygotic knockdowns of Pt-vasa did not prevent PGC formation. However, Ptvasa is required maternally for egg laying, mitotic progression in early embryos, and embryonic survival. My results thus provide evidence for a previously hypothesized conserved role for Pt-vasa in cell cycle progression.
Projektbezogene Publikationen (Auswahl)
- 2012. Evolution of the chelicera: a dachshund domain is retained in the deutocerebral appendage of Opiliones (Arthropoda, Chelicerata). Evolution & Development, 14(6), pp.522–533
Sharma, P.P., Schwager, E.E., Extavour, C.G. & Giribet, G.
- 2012. Hox gene expression in the harvestman Phalangium opilio reveals divergent patterning of the chelicerate opisthosoma. Evolution & Development, 14(5), pp.450–463
Sharma, P.P., Schwager, E.E., Extavour, C.G. & Giribet, G.
- 2012. Oskar predates the evolution of germ plasm in insects. Current biology : CB, 22(23), pp. 2278–2283
Ewen-Campen, B., Srouji, J.R., Schwager, E.E. & Extavour, C.G.
- 2013. Distal-less and dachshund pattern both plesiomorphic and apomorphic structures in chelicerates: RNA interference in the harvestman Phalangium opilio (Opiliones). Evolution & Development, 15(4), pp.228–242
Sharma, P.P., Schwager, E.E., Giribet, G., Jockusch, E.L. & Extavour, C.G.
