Steroid resistance in childhood leukemia associated with IL7 receptor pathway mutations
T-cell acute lymphoblastic leukemia (ALL) in children is often associated with resistance to key treatments, including steroids. Yunlei Li from the Erasmus Medical Center-Sophia Children’s Hospital and colleagues conducted whole genome sequencing of tissue samples from 13 patients pre- and post-steroid treatment, and found that mutations in two genes, JAK1 and KRAS, encoding components of the IL7 receptor pathways, were associated with steroid resistance and worse outcomes after treatment. In future, inhibition of components of this pathway might potentially enhance steroid sensitivity in T- cell ALL, improving patient treatment outcomes.
Jujube genome provides insight into fruit domestication
The Chinese jujube, domesticated from the wild jujube, is an important fruit tree crop. Jian Huang from Northwest A&F University and colleagues sequenced the genomes of wild and domesticated jujubes, and found that regions featuring genes involved in fruit sugar content and acid metabolism were identical between cultivated varieties, showing that once humans had identified jujubes with the right balance of sweetness and acidity, only plants with those genes were widely cultivated. Other genome regions varied: the Dongzao variety, a crisp jujube which is eaten fresh, has a recent genome insertion that the Junzao variety, eaten dried, does not have. The study provides insights into how the jujube has evolved under human cultivation and the role of domestication in shaping its genome.
‘Grey zone’ of speciation occurs in fixed range of genetic divergence
Speciation occurs when two isolated populations of a species undergo genetic divergence, accumulating distinct genetic mutations until they can no longer interbreed to produce fertile offspring. The ‘grey zone’ of speciation is the degree of genetic divergence with which two populations may or may not be considered as distinct species. Camille Roux from the Université Montpellier and the University of Lausanne and colleagues conducted a comparative analysis of the genomes of 61 paired populations of animals, and for most pairs successfully determined whether or not they were distinct species. The authors found that regardless of the species’ life history and ecology, the ‘grey zone’ of speciation spanned around 0.5% to 2% of genetic divergence; that is, the genomes of the two populations were around 0.5% to 2% different. They also identified many semi-isolated species, highlighting the intrinsic difficulty of defining species.
Image Credit: Huang et al., 2016