Research Interests
Drosophila oogenesis, the development of the egg, is one of the most intensely studied developmental systems. In contrast, there is little known about the development of the ovary itself. The reason for this has been the lack of cellular markers and genetic mutants. During the past four years we have begun to characterize ovary development using a genetic approach. Our work shows that the ovary will be an excellent system for determining how cells interact with each other during the development of an organ. The Drosophila ovary consists of repeated units, the ovarioles, where oogenesis takes place. The repetitive structure of the ovary develops de novo from a mesenchymal cell mass, a process which is initiated by the formation of a two-dimensional array of cell stacks, called terminal filaments, during the third larval instar. We have studied the development of the terminal filaments and their regular spatial arrangement, as well as the formation of the structurally related basal and interfollicular stalks. We find that they develop through recruitment and cell intercalation of mesenchymal cells, a process resembling the formation of the notochord by convergence and extension in a chordate embryo. Furthermore, we have found that the pattern forming process through which multiple terminal filaments arise from a common cell population requires cell sorting. We believe that a differential distribution of adhesion molecules on the surface of the terminal filament cells is involved in this sorting process. We also find that the Drosophila gene bric à brac (bab) is cell autonomously required for the formation of terminal filaments and is crucial for normal morphogenesis of the ovary. bric à brac has also been shown to be required for proper segmentation and specification in leg primordia, and encodes a nuclear protein which contains a BTB domain, a conserved domain that is found in several transcriptional regulators as well as other proteins. Disruption of terminal filament formation leads to a disruption of ovariole formation and female sterility in bric à brac mutants. We are now in the process of isolating and characterizing new genes that are involved in ovary and limb development.
Selected Publications
Corinne Lours, Olivier Bardot, Dorothea Godt, Frank A. Laski and Jean-Louis Couderc. 2003. The Drosophila melanogaster BTB proteins bric a brac bind DNA through a composite DNA binding domain containing a pipsqueak and an AT-Hook motif Nucleic Acids Research 31: 5389-5398 .
Cabrera, Gwendolyn R., Dorothea Godt, Peir-Yu Fang, Jean-Louis Couderc, and Frank A. Laski. 2002. Expression pattern of Ga14 enhancer trap insertions into the bric a brac locus generated by P element Genesis 34: 62-65 .
Couderc, Jean-Louis,Dorothea Godt,Susan Zollman, Jiong Chen, Michelle Li, Stanley Tiong, Sarah E. Cramton, Isabelle Sahut-Barnola, and Frank A. Laski. 2002. The bric a brac locus consists of two paralogous genes encoding BTB/POZ domain proteins, and acts as a homeotic and morphogenetic regulator if imaginal development in Drosophila Development 129: 2419-2433 .
Bardot, Olivier, Dorothea Godt, Frank A. Laski, and Jean-Louis Couderc. 2002. Expressing UAS-bab1 and UAS-bab2: A comparative study of gain of function effects and the potential to rescue the bric a brac mutant phenotype Genesis 34: 66-70 .
Rio, Donald C., Frank A. Laski and Gerald M. Rubin. 1996. Identification and immunochemical analysis of biologically active Drosophila P element transposase Cell 44: 21-32 .
Godt, Dorothea and Frank A. Laski. 1995. Mechanism of cell rearrangement and cell recruitment in Drosophila ovary morphogenesis and the requirement of a bric a brac Development 121: 173-187 .
Sahut, Isabelle, Dorothea Godt, Frank A. Laski and Jean-Louis Couderc. 1995. Drosophila ovary morphogenesis: analysis of terminal filament formation and identification of a gene required for this process Developmental Biology 170: 127-135 .
Cramton, Sarah E. and Frank A. Laski. 1994. String of pearls encodes Drosophila ribosomal protein S2, has Minute-like characteristics, and is required during oogenesis Genetics 137: 1039-1048 .
Zollman, Susan, Dorothea Godt, Gilbert G. Prive, Jean-Louis Couderc and Frank A. Laski. 1994. The BTM domain, primarily found in zinc finger proteins, defines an evolutionarily conserved family that includes several developmentally regulated genes of Drosophila Proc. Natl. Acad. Sci. USA 91: 10717-10721 .
Godt, Dorothea, Jean-Louis Couderc, Sarah E. Cramton and Frank A. Laski. 1993. Pattern formation in the limbs of Drosophila: Bric a Braqc is expressed in both a gradient and a wave-like pattern and is required for specification and proper segmentation of the tarsus Development 119: 799-812 .