Email: nschaeper@berkeley.edu

Research Summary

Studies in the fruit fly Drosophila melanogaster showed that head segmentation mechanisms differ significantly from the well-studied mechanisms underlying trunk segmentation. In the anterior head region, activity of Hox genes and pair rule genes is missing. However, despite the belief that head segmentation mechanisms are conserved during evolution, they have not been identified sufficiently in any organism. Because a fly maggot has “no real head”, I want to analyze head pattering mechanisms in different other arthropod species, like the amphipod crustacean Parhyale hawaiensis, the red flour beetle Tribolium castaneum, the milkweed bug Oncopeltus fasciatus as well as in basic insects like the springtail Folsomia candida and the firebrat Thermobia domestica. Therefore, I want to isolate and functionally characterize genes, which are crucial for early head development in these arthropods species to draw conclusions about head patterning mechanisms. 

The Drosophila gene buttonhead (btd) is involved in early head development. This head gap gene belongs to the Sp/KLF (specifity protein/Krueppel like factor) family of transcription factors. Homologues of this family are also found in vertebrates. In the genome of Drosophila melanogaster (Dm) three homologues of the Sp-family can be found: Sp1/3/4 (CG5669), Sp8/9 (D-Sp1, CG1343) and buttonhead (CG12653). Homologues of these three genes can also be found in other insect species: Anopheles gambiae, Apis mellifera, Bombyx mori, Clogmia albipunctata, Tribolium castaneum. In the genomes of vertebrates like mouse, human and chick, nine homologues of the Sp-family are known: Sp1-9 but there is no direct btd homologue. In the genomes of the crustacean Daphnia pulex, the nematode Caenorhabditis elegans and the cnidarian Nematostella vectensis you can find a Sp1/3/4 and Sp8/9 gene and also a third Sp factor gene, which is not btd but Sp5. I isolated the same three Sp factors genes (Sp1/3/4, Sp5, Sp8/9) from the basic insects Folsomia candida and Thermobia domestica.

Dm btd and Dm Sp8/9 show redundant function in Drosophila. Both genes are involved in the formation of appendages as well as in the formation of CNS and PNS. But only btd is directly involved in head development. Interestingly, the Mus musculus (Mm) Sp8 shows a functional relationship to Dm btd. Mm Sp8 is also involved in formation of appendages and in head development. But this gene shows higher sequence similarity to Dm Sp8/9 than to Dm btd. Data for Sp5 from mouse and zebra fish show gene expression in the mid-hindbrain boundary and the tail bud of these animals, which is similar to the expression of Dm btd.

Due to the different combinations of Sp factors and similar expression patterns of Sp5, Sp8/9 and btd in bilaterians, several questions arise: is the btd gene restricted to insects and other Sp homologues take part in head development of non-insect arthropods like Sp8/9 and Sp5 in vertebrates? What happened to Sp5 in insects and can functional similarities in head development of Sp5, Sp8/9 and btd be determined? I want to investigate this by comparing the genetic sequences and expression patterns of Sp factors in Parhyale, Folsomia, Thermobia, Oncopeltus and Tribolium. Currently I am establishing in-situ stainings for Folsomia candida. For functional gene analysis in Parhyale we are exploring techniques for knockdown and misexpression experiments. In addition I am interested in collier and cap`n`collar homologues of Parhyale, Tribolium, Oncopeltus and Folsomia because these genes are target genes for Dm btd and also important for early head development in Drosophila. We hope with this comparative analysis, we will find out more about the evolution of head patterning mechanisms in arthropods.

Education:

Visiting student in Dept. of Integrative Biology
University of California, Berkeley
Host: Nipam H. Patel
August 2006- May 2007

Ph.D. student
Georg-August University Goettingen, Germany
Dept. of Developmental Biology
Advisor: Prof. Ernst A. Wimmer
2005 - present

Diploma in Biology
Georg-August University Goettingen, Germany
Dept. of Developmental Biology
Advisor: Prof. Ernst A. Wimmer
2000 – 2005