Danielle Beekman and Danielle Rudd will present their research on 21st June 2012.

Danielle Beekman’s research abstract

Examining the Origin and Evolution of Male Achiasmatic Meiosis in Drosophila

Drosophila melanogaster is unique amongst model organisms in that males undergo achiasmatic meiosis, where synaptonemal complex (SC) formation and recombination are absent. A number of male achiasmatic meiosis-specific genes have been identified and many are paralogous to non-meiotic genes. My research investigates the origin and evolution of male meiosis-specific genes using bioinformatics and molecular genetics approaches. Recently, I have been analyzing the expression and splicing of meiosis genes in male and female Drosophila. Interestingly, many genes which were believed to have sex-specific functions were found to be expressed and correctly spliced in both sexes. My results also show that there is no single means of regulation for these meiosis genes, suggesting that multiple different mechanisms of gene regulation are at work in preparation for and during meiosis in Drosophila.


Danielle Rudd’s research abstract

Genome-wide CNV analysis of schizophrenia subjects

Schizophrenia is characterized by positive and negative symptoms that include hallucinations, delusions and disorganized thought as well as flat affect and decreased speech. Genomic copy number variation (CNV) has been found to underlie and increase risk for a large number of neuropsychiatric disorders like schizophrenia. This project focuses on identification and characterization of pathogenic CNVs in a sample set of 457 schizophrenia patients and 290 psychiatrically healthy controls. To date, 167 probands and 101 controls have been genotyped using the Affymetrix Genome-Wide Human SNP 6.0 Arrays and analyzed for CNVs with Genotyping Console and PennCNV. CNVs were compared between cases and controls and cross-referenced with the Database of Genomic Variants. The proximal arm of chromosome 15 contains canonical segmental duplications that predispose the region to CNV formation, but only recently have disease-associated CNVs been reported between the two most proximal breakpoints (BPs), BP1 and BP2. Here we report three case subjects that have a ~1Mb deletion of the BP1-BP2 region at chromosome 15q11.2. The BP1-BP2 deletion encompasses the four genes CYFIP1, NIPA1, NIPA2 and GCP5, is present in three probands, two of which were maternally inherited, but not in controls. All CNVs of interest were validated by qPCR or NimbleGen 385K whole-genome array CGH. The four genes within the CNV have previous association with Prader Willi syndrome, Angleman syndrome, autism and schizophrenia and are often inherited from a mildly or unaffected parent. CYFIP1 is of primary interest due to its direct interaction with the Fragile X Mental Retardation Protein (FMRP) and its reported role in regulation of neuronal translation during brain development. NIPA1, NIPA2 and GCP5 are also expressed in the brain. To see if the CNV unmasked any recessive variants on the remaining allele, that allele was sequenced and no such variants were identified. It is unlikely that the 15q11.2 CNV alone is pathogenic because it is such a common region of variation. Therefore each case was investigated further for other compelling CNV hits, based on a “multi-hit” CNV hypothesis where multiple CNVs as a group are pathogenic to schizophrenia. The two probands with maternal inheritance of the deletion were further analyzed for sporadic secondary CNVs. Examples of other compelling CNVs are a de novo duplication of four exons of ATXN2 de novo duplication of two exons CACNA1B and DLGAP2.


Posted on June 15, 2012, in Student Seminar. Bookmark the permalink. Leave a comment.

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