Early development of Drosophila embryos requires Smc5/6 function during oogenesis.

Mutations in structural maintenance of chromosomes (Smc) proteins are frequently associated with chromosomal abnormalities commonly observed in developmental disorders. However, the role of Smc proteins in development still remains elusive. To investigate Smc5/6 function during early embryogenesis we examined smc5 and smc6 mutants of the fruit fly Drosophila melanogaster using a combination of reverse genetics and microscopy approaches.

Chromosome length influences replication-induced topological stress.

During chromosome duplication the parental DNA molecule becomes overwound, or positively supercoiled, in the region ahead of the advancing replication fork. To allow fork progression, this superhelical tension has to be removed by topoisomerases, which operate by introducing transient DNA breaks. Positive supercoiling can also be diminished if the advancing fork rotates along the DNA helix, but then sister chromatid intertwinings form in its wake.

Genome wide distribution of illegitimate recombination events in Kluyveromyces lactis.

Illegitimate recombination (IR) is the process by which two DNA molecules not sharing homology to each other are joined. In Kluyveromyces lactis, integration of heterologous DNA occurred very frequently therefore constituting an excellent model organism to study IR. IR was completely dependent on the nonhomologous end-joining (NHEJ) pathway for DNA double strand break (DSB) repair and we detected no other pathways capable of mediating IR.

Functional diversity of silencers in budding yeasts.

We studied the silencing of the cryptic mating-type loci HMLa and HMRa in the budding yeast Kluyveromyces lactis. A 102-bp minimal silencer fragment was defined that was both necessary and sufficient for silencing of HMLalpha. Mutagenesis of the silencer revealed three distinct regions (A, B, and C) that were important for silencing.