In this week's Nature Genetics, a multi-institute team publishes a nearly complete reference genome of the cultivated octoploid strawberry, which resulted from the hybridization of two wild octoploid species that descended from the merger of four diploid progenitor species into a single nucleus more than one million years ago. The researchers uncovered evidence of the plant's North American origin, as well as the existence of a dominant subgenome that largely controls metabolomic and disease-resistance traits. "We anticipate that this new reference genome, combined with insights into subgenome dominance, will greatly accelerate molecular breeding efforts in the cultivated garden strawberry," the authors write. GenomeWeb has more on this, here.
And in Nature Ecology & Evolution, researchers from the US and Korea present a high-quality genome assembly and linkage map for the Antarctic blackfin icefish Chaenocephalus aceratus — a so-called white blooded vertebrate that lacks functional red blood cells and functional hemoglobin genes. The researchers identified genes involved in protection from ice damage — including genes encoding antifreeze glycoprotein and zona pellucida proteins — that are highly expanded in the icefish genome. They also found an expansion of genes that encode enzymes that help to control cellular redox state, likely as evolutionary adaptations to the relatively high concentration of oxygen dissolved in cold Antarctic waters. Meanwhile, some crucial regulators of circadian homeostasis are found to be absent from the icefish genome, suggesting compromised control of biological rhythms in the polar light environment, they write.
Meanwhile, in Nature Cell Biology, a group from Peking University reports a microRNA-inducible CRISPR-Cas9 platform that can both measure miRNA activity at the cellular level and control the expression of endogenous genes or mutate specific DNA bases on a cell type-specific basis. They use the system to study the heterogeneity of miRNA activity and uncover a previously undefined layer of heterogeneity associated with miR-21a activity in mouse embryonic stem cells. "These results highlight the utility of an miRNA-induced CRISPR–Cas9 system as miRNA sensors and cell-type-specific genome regulation tools," the investigators write.