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This Week in PNAS: Aug 23, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the University of British Columbia and elsewhere explore the chromosome instability consequences of gene overexpression in the budding yeast Saccharomyces cerevisiae. The team's initial screen turned up 245 genes that appeared to cause dosage chromosome stability, including two genes subsequently linked to chromosome instability when expressed at higher-than-usual levels in human cells. Moving to synthetic dosage lethal yeast screens, the group went on to search for genetic vulnerabilities in cases chromosome instability associated with overexpression — a strategy expected to help in identifying candidate pathways that may be targeted in some tumor cells with chromosomal instability.

Genome sequences for the indica rice lines Zhenshan 97 and Minghui 63 suggest the two varieties have significant structural differences and sequence divergence. As they report in a PNAS study, researchers from China, the US, and the Philippines did map-based sequencing on the major Oryza sativa subspecies indica varieties Zhenshan 97 and Minghui 63, generating sequences that spanned roughly 90 percent or more of each genome. Along with divergence between the new indica genomes, the study's authors identified distinct transcriptome patterns in three tissues from a hybrid cross between the two parental lines, noting that "the expressed genes in the hybrid were much more diverse due to their divergence between the parental genomes."

A Stanford University-led team takes a look at pre- and post-synaptic interactions in the mouse brain. After considering transcriptional patterns in bulk hippocampus samples from five stages of mouse development, the researchers isolated individual neurons and inter-neuron cells based on their electrophysiological patterns. Together, the messenger RNA sequences provided a peek at the cell adhesion- and signaling-related genes at play at synapses in different brain cell types and circumstances. "Our approach provides a framework for a presumed cell adhesion and signaling code in neurons, enables correlating electrophysiological with molecular properties of neurons, and suggests avenues toward understanding synaptic specificity," they write.