Ohkura Lab paper featured in Chromosoma. Authors Nieken, K.J., O'Brien, K., McDonnell, A., Zhaunova, L., and Ohkura, H. Image Nieken et al have carried out an unbiased large-scale screen to identify genes involved in the formation of the compact cluster of meiotic chromosomes called the karyosome in oocytes of fruit flies. This screen has identified 106 highly interconnected genes including genes involved in chromatin, nuclear envelope, actin and mitochondria. Summary of Paper by Lori Koch During the formation of oocytes for sexual reproduction, the chromosomes cluster together within the cell near the nuclear envelope before it breaks down and later the spindle forms to move the chromosomes into the new cells. Previous studies identified that the formation of this chromosome cluster, named the karyosome, is essential to form healthy cells. In their recent research published in Chromosoma, scientists in the Ohkura lab led by Dr. Jule Nieken performed an unbiased screen to identify genes involved in the formation of the karyosome in oocytes of fruit flies. Their screen covered 3,916 genes expressed in ovaries and whose expression could be prevented using available RNAi lines. They discovered that knockdown of 106 of the genes (2.7%) resulted in abnormally shaped karyosomes and included a handful of genes previously identified to be essential for this process, such as genes involved in chromatin and nuclear envelope integrity as well as actin filaments. Curiously, they also identified 20 genes (19%) involved in mitochondria function and they found that knock down of 60% of these genes resulted in a unique shape of the karyosome where all the chromosomes appear tightly attached to the nuclear envelope. Dr. Nieken and her colleagues hypothesized that mitochondrial dysfunction was triggering programmed cell death and so they examined the effect of triggering cell dealth in otherwise normal flies. This revealed that the effects of programmed cell dealth were distinct from those caused by knockdown of the 20 mitochondrial genes identified. Finally, the study identified 15 genes with currently unknown function to be essential for karyosome formation and future work may help elucidate their role in oocytes. Related links Journal Link Ohkura Lab website DOI This article was published on 2024-06-17
