Meiosis & Chromosome Dynamics

Team

Harry Scherthan, guest scientist
eMail: schertha@molgen.mpg.de

Meiosis is the central event of sexual reproduction, by which haploid gametes are formed from diploid cells by two ensuing cell divisions that lack an intervening S-phase. This halving of the chromosome number compensates for the genome doubling that occurs at fertilization. Furthermore, meiosis represents the general source of genetic variation in the offspring of sexually reproducing organisms: During the specialized prophase to the meiosis I division parental chromosomes recombine and exchange genetic material by double stranded DNA break repair. To this end, homologous chromosomes have to reorganize their structure and positioning which leads to their synaptic pairing during mid prophase I. Chromosome pairing and/or recombination fulfill the task of tethering parental chromosomes to each other, which allows their faithful segregation at meiosis I.

Research in model systems has shown that genes which contribute to meiotic chromosome structure and recombination are vital for meiotic differentiation and fertility. Some of such genes have been found mutated in infertile humans. Telomeres are protein complexes at the ends of linear chromosomes. They can mediate transcriptional repression and epigenetic effects and contribute to genomic stability. Long-standing hypotheses predict that telomeres carry out vital functions in the meiotic homologue pairing process and hence fertility. At meiosis, specific protein additions to the telomere complex are associated with intranuclear repositioning and a novel, nuclear envelope-associated dynamic mobility of telomeres.

We comparatively analyze the role of specific proteins for meiotic chromosome behavior and dynamics with an emphasis on meiotic telomere clustering (bouquet formation). Molecular cytology and live cell analysis is applied to study prophase I events in mutants of mammals, budding yeast and in patients.