טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGattegn0 Tamar
SubjectIsolation and Characterization of Cell-Fusion Mutants in
C. Elegans
DepartmentDepartment of Biology
Supervisors Professor Gera Eytan
Professor Benjamin Podbilewicz


Abstract

Cell fusion is a universal developmental process that occurs in numerous organisms and is abundant in C. elegans epithelia and pharyngeal muscles. Cell to cell fusion is being studied in several model organisms and by means of in vitro systems. Studies of enveloped viruses identified viral membrane glycoproteins essential for fusion that were termed fusogens. In C. elegans genes that have been identified to be involved in cell fusion are regulatory factors, except for eff-1 (epithelial fusion failure), which encodes novel type- I transmembrane proteins, and is a candidate to be involved in the actual fusion machinery.

We are using the nematode Caenorhabditis elegans as a model system to better understand the molecular machinery of somatic cell fusion. Thus far, genetic screens designed to find fusion-affected mutants yielded merely eff-1 alleles. We have made a wide two-step EMS (Ethylmethanesulfonate) screen, resulting in the isolation of five new viable cell fusion mutants that displayed a complete blockage of cell-cell fusion events. All five new mutants that were isolated in our screens were found to be new eff-1 alleles, though we isolated 66 additional mutants that were partially affected in the fusion process.

We analyzed the zygotic lethal idf-1(irregular dorsal fusion) (zu316) mutation which is specifically affected in dorsal embryonic fusion events. In order to learn about idf-1 normal function we analyzed zu316 embryonic hypodermis fusion pattern. The number and identity of the unfused cells was found to be extremely variable. We found two overlapping YACs and a common cosmid which partially rescued zu316 animals in transformational rescue experiments.