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The DNA methyltransferase DNMT1 is essential for cell viability in various mouse models, but gene targeting in human tumor cells results in a viable line. This dilemma has now been resolved using a new human DNMT1 knockout line, although new questions arise as to the full extent of DNMT1 function in maintaining genome integrity.
Deeply hidden in the bone marrow are rare hematopoietic stem cells that produce all types of blood cells in the circulatory system. A new study shows that the latexin gene affects the size of this population of cells.
Members of the Hedgehog family of secreted proteins are central to animal development, with different levels of Hedgehog signaling activity specifying distinct cellular identities. A new study shows that a microRNA is involved in this process by modulating a component of the Hedgehog signal transduction pathway.
Two new studies show that the Fanconi anemia complementation group N results from biallelic mutations in PALB2, which encodes a recently identified interaction partner of the breast cancer susceptibility protein BRCA2. A third study shows that monoallelic PALB2 mutations are associated with breast cancer susceptibility, providing yet more links between Fanconi anemia, homologous recombination repair and cancer predisposition.
A new study identifies 'quantitative trait transcripts' for nicotine resistance in large populations of wild strains of Drosophila melanogaster by comparing global gene expression patterns, survival time and metabolite levels in the presence or absence of nicotine. The results provide proof-of-concept for a correlation-based statistical approach that can be used in personalized medicine.
A new study examines the agn43 epigenetic switch of Escherichia coli, providing an alternative to feedback regulation as a model for gene expression regulation. Through a combination of synthetic network construction and computational modeling, the authors show that the generated bistable gene expression involves transitions between several rarely occupied states between 'on' and 'off'.
Telomere dysfunction suppresses cancer through the p53 tumor suppressor pathway but also contributes to aging. A new study suggests that these effects of dysfunctional telomeres may be separable, such that aging—but not cancer suppression—depends on the p21 cell cycle inhibitor.
Noonan syndrome is a disease caused by aberrant signaling through the Ras GTPase, yet the underlying causal mutations remain unknown in many affected individuals. Two papers now identify gain-of-function mutations in the Ras nucleotide exchange factor SOS1 as a new player in this common developmental disorder.
Replication initiation factors are essential for cell proliferation and thus are not expected to be disrupted in cancers. Challenging this notion, a new study in mice shows that a hypomorphic mutation in the gene encoding the replication initiation factor Mcm4 leads to genetic instability and predisposes to mammary adenocarcinomas.
Three new studies provide a genome-wide snapshot of genetic variation in Plasmodium falciparum, the most pathogenic of the parasites causing human malaria. These studies pave the way for mapping of genes underlying important parasite traits such as drug resistance and pathogenesis as well as for evolutionary analysis of selection in a parasite genome.
The ability to digest lactose into adulthood is a recently evolved trait that has risen to high frequency in some human populations, coincident with the introduction of cattle domestication. A new study shows that variants responsible for this trait arose independently in Europeans and Africans, providing a striking example of convergent evolution.