Positioning of homologous chromosome 15

in Bloom's Syndrome

Presenter: Christian Quintero

Co-Presenter(s):
Jemery Morales

Presenter Status: Undergraduate student

Academic Year: 22-23

Semester: Spring

Faculty Mentor: Lisa Hua

Department: Biology

Funding Source/Sponsor: Koret Scholars Program

Other Funding Source/Program: CSUPERB, LSAMP, NSF

Abstract:
In meiosis, pairing and recombination between homologous chromosomes occurs for genetic diversification. In mitosis, however, unregulated pairing and recombination between homologs can lead to genomic instability (Karpenshif and Bernstein, 2012). It has been discovered that homologous chromosomes are spatially separated along the centrosome axis in dividing human cells (Hua and Mikawa, 2018). The homologous segregation, or antipairing pattern, functions to prevent abnormal pairing that may lead to genomic misregulation, loss of heterozygosity, and cancer (Hua and Mikawa, 2018). However, it is unknown whether the loss of antipairing is directly correlated with an increased frequency of abnormal pairing and mitotic recombination. Bloom’s Syndrome (BS) is an autosomal recessive disorder characterized by chromosomal aberrations and abnormal homologous recombination (Therman and Kuhn, 1976). The chromosomal aberrations such as quadriradial formation for chromosome 15, has been correlated with mitotic chiasmata, reciprocal chromosome exchange, and chromatid translocations (Therman and Kuhn, 1976). To test whether there is a loss of antipairing prior to quadriradial formation, we will perform high resolution confocal microscopy and chromosome painting for chromosome 15 of BS cells. We hypothesize homologous chromosome 15 will lose the antipairing pattern, and abnormally pair. Understanding the phenotypic manifestations of the loss of proper chromosome organization can provide insight to human disease.