Drosophila embryonic cell-cycle mutants

Area of Science:

• Developmental Biology
• Cell Biology
• Genetics

Background:

• Drosophila larval development relies on ploidy increase, not cell division, masking cell cycle mutants.
• Most cell division mutants are identified in late larval/pupal screens, missing embryonic lethal phenotypes.
• Identifying embryonic cell division mutants is crucial for understanding early development.

Purpose of the Study:

• Screen for Drosophila mutants with defects in cell division during embryogenesis.
• Investigate the function of Cyclin E in neuroblast cell fate determination.
• Identify genes essential for embryonic cytokinesis and mitosis.

Main Methods:

• Conducted a forward genetic screen for embryonic lethal cell division mutants in Drosophila.
• Generated and analyzed new alleles of Cyclin E, including missense and stop codon mutations.
• Examined phenotypes of mutations in pavarotti (pav), tumbleweed (tum), CAL1, and Spc105R in embryonic tissues.

Main Results:

• Recovered five new alleles of Cyclin E, with varying effects on viability and neuroblast cell fate.
• Truncating Cyclin E mutations impacted NB6-4 neuroblast cell fate, while a missense mutation did not.
• Identified mutations in pav and tum genes causing multinucleate cells, indicating cytokinesis defects.
• Observed mitotic defects in the nervous system associated with mutations in CAL1 and Spc105R.

Conclusions:

• Embryonic screens are vital for uncovering essential cell cycle genes with early developmental roles.
• Cyclin E plays a critical role in embryonic neuroblast cell fate determination.
• Pavarotti, tumbleweed, CAL1, and Spc105R are essential for accurate cell division during Drosophila embryogenesis.