Researchers from China and the US present a Cell study highlighting the genomic information that can be obtained for individual human eggs. The team collected oocytes from eight healthy Asian women and injected them with sperm, before using micromanipulation to isolate female pronuclei and polar bodies from the fertilized oocytes. For 180 cells obtained in this fashion, the team did single cell sequencing with the help of a multiple annealing and looping-based amplification cycle (MALBAC) amplification method. With the resulting sequences, the researchers reported that they could not only pick up aneuploidy events and SNP profiles, but also recombination patterns across the egg genome. As such, the study's authors argue that their method may be prove useful for pre-implantation screening during in vitro fertilization.
A Drosophila microRNA called miR-9a appears to interact with the transcription factor "Senseless" to diminish some of the phenotypic effects of the genomic diversity in the fruit fly, a Northwestern University-led team determined. The researchers did a series of multigenerational selection experiments involving fruit flies from different genetic backgrounds in an effort to better understand how miRNAs mediate the interplay between genomic diversity and gene activity in the fruit fly's so-called proneural network. In that system, the team found that lower-than-usual miR-9a allowed a wider set of variants to alter fly phenotypes by acting on the gene coding for Senseless.
Chromatin architecture and protein degradation machinery can work together to influence gene regulation by transcription factors in mammalian cells, according to another Cell study. A Harvard University-led team developed an assay using presence of proteasome-sensitive ubiquitin on DNA to help map the genome-wide distribution of DNA interacting proteins on track for destruction by the cell's proteolysis machinery. With this approach and follow-up experiments, the researchers detected a relationship between the proteolytic degradation of certain transcriptional repressors and the activity of transcription factors found at certain promoter and enhancer sequences. In particular, their results hint that proteolysis of the nuclear co-repressor NCoR1 unleashes genes controlled by the transcription factor CREB, while the presence of stable NCoR1 led to lower-than-usual expression of CREB-regulated genes.