GENETIC AND MOLECULAR ANALYSIS OF CELL DIVISION IN DROSOPHILA MELANOGASTER

GROUP LEADER: Maurizio Gatti

SCIENTISTS: Silvia Bonaccorsi, Patrizia Somma, Patrizio Dimitri, Romano Petrucci, Fiammetta Verni'

POSTDOCTORAL FELLOWS: Mark Tudor, Giovanni Cenci, Maria Grazia Giansanti

GRADUATE STUDENTS: Barbara Fasulo

TECHNICAL ASSISTANTS: Giorgio Belloni, Maria Pia Belloni

 

ABSTRACT:

One of the main interests of our laboratory is the genetic and molecular analysis of cell division in Drosophila melanogaster. In the past decade we have developed efficient methods for the isolation and cytological characterization of mutations affecting the mitotic cell division of larval neuroblasts. More recently we have elaborated a series of techniques that allow detection and analysis of mutations affecting male meiosis. Primary spermatocyte nuclei are about 25 times larger than neuroblast nuclei and exhibit comparatively larger spindles. Thus, male meiosis is a particularly suitable system for the analysis of spindle structure and immunolocalization of spindle-associated proteins. We are currently focusing on the genetic and molecular analysis of meiotic cytokinesis in males. We have already identified 10 mutations that disrupt this process, most of which are caused by the insertion of a single, marked P element. Moreover, we are continuing P-mutagenesis to recover new mutants defective in the completion of cytokinesis. Other mutations affecting cytokinesis have been isolated by other groups [spaghetti squash (sqh), diaphanous (dia), peanut (pnut)]. All the genes in hand are being characterized at several levels: (1) by defining the primary defects that lead to disruption of cytokinesis in male meiosis of mutants; (2) by molecular cloning and sequencing of each gene; (3) by the production of antibodies against the gene products and their immunolocalization during male meiosis; (4) by studying functional interactions among genes using a variety of approaches. Our studies have already led to the identification of some proteins required for meiotic cytokinesis in males, and to the definition of their biological roles. We believe that continuation of this research will provide substantial insight into the mechanisms underlying cytokinesis in animal cells.
In addition to mutations that disrupt cytokinesis, we are currently analyzing mutations affecting telomere behaviour during both mitosis and male meiosis. We have recently isolated mutations at four loci that cause frequent telomere-telomere attachments. One of the genes specified by these mutations, UbcD1, has been shown to encode an ubiquitin-conjugating enzyme (E2). This suggests that ubiquitin-mediated proteolysis is required for proper telomere behaviour.

 

COLLABORATIONS:

Michael L. Goldberg, Section of Genetics and Development, Cornell University, Ithaca, NY

 

PUBLICATIONS:

- Gatti M. and Pimpinelli S. (1992) Functional elements in Drosophila melanogaster heterochromatin. Annu. Rev. Genet. 26: 239-275

- Pisano C., Bonaccorsi S. and Gatti M. (1993) The kl-3 loop of the Y chromosome of Drosophila melanogaster binds a tektin-like protein. Genetics, 133: 569-579

- Gatti M., Bonaccorsi S. and Pimpinelli S. (1994) Looking at Drosophila mitotic chromosomes. Methods in Cell Biol. 44, 371-391.

- Cenci G., Bonaccorsi S., Pisano C., Verni' F. and Gatti M. (1994) Chromatin and microtubule organization during premeiotic, meiotic and early postmeiotic stages of Drosophila melanogaster spermatogenesis. J. Cell Sci. 107, 3521-3534

- Gunsalus K., C., Bonaccorsi S., Williams E., Verni' F., Gatti M. and Goldberg M. L. (1995) Mutations in twinstar, a Drosophila gene encoding a cofilin/ADF homolog, result in defects in centrosome migration and cytokinesis. J. Cell Biol., 131, 1243-1259

- Pimpinelli S., Berloco M., Fanti L., Dimitri P., Bonaccorsi S., Marchetti E., Caizzi R., Caggese C. and Gatti M. (1995) Transposable elements are stable structural components of Drosophila melanogaster heterochromatin. Proc. Natl. Acad Sci. USA, 92, 3804-3808.

- Williams B. C., Riedy M. F., Williams E. V., Gatti M. and Goldberg M. L..(1995) The Drosophila kinesin-like protein KLP3A is a midbody component required for central spindle assembly and initiation of cytokinesis. J. Cell Biol., 129, 709-723.

- Giansanti M. G., Bonaccorsi S., Williams B. C., Gunsalus K. C., Goldberg M. L. and Gatti M. (1996) Genes controlling cytokinesis during meiosis in Drosophila males. In: Proceedings on Chromosome segregation and aneuploidy, III. ( A. Abbondandolo, B. K. Vig and Roi R. Eds.) IST Genova, pp 304-316

- Verni' F., Somma M. P., Gandhi R., Goldberg M. L. and Gatti M. (1996) Genes controlling chromosome structure in Drosophila melanogaster. In: Chromosomes Today 12. (N. Henriques-Gil, J. S. Parker and M.J. Puertas Eds.) Chapman and Hall, London, pp 88-103

- Williams B. C., Gatti M. and Goldberg M. L. (1996) Bipolar spindle attachments affect redistribution of ZW10, a Drosophila centromere/kinetochore component required for accurate chromosome segregation. J. Cell Biol., 34, 1127-1140

- Cenci G., Rawson R., Belloni G., Castrillon D. H., Tudor M., Petrucci R., Goldberg M. L., Wasserman S. A. and Gatti M. (1997) UbcD1, a Drosophila ubiquitin conjugating enzyme required for proper telomere behavior. Genes and Dev. 11, 863-875

- Giansanti M. G., Bonaccorsi S., Williams B., Williams E. V., Santolamazza C., Goldberg M. L. and Gatti M. (1997) Mutations in the profilin-encoding gene chickadee reveal interactions between the actin cytoskeleton and the ana-telophase central spindle during meiosis in Drosophila melanogaster males. Genes and Dev., in press

 

REVIEWS AND SELECTED PAPERS:

- Gatti M., Smith D. A. and Baker B. S. (1983). A gene controlling condensation of heterochromatin in Drosophila melanogaster. Science 221: 83-85.

- Gatti M. and Baker B. S. (1989) Genes controlling essential cell-cycle functions in Drosophila melanogaster. Genes and Development 3: 438-453.

- Gatti M. and Goldberg M. L. (1991) Mutations affecting cell division in Drosophila. Methods in Cell Biol.35: 543-585.