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This Week in PNAS: Sep 24, 2014

In the early edition of the Proceedings of the National Academy of Sciences, an international team led by investigators at the University of Copenhagen and BGI-Shenzen present the genome sequence for the termite Macrotermes natalensis and a symbiotic Termitomyces fungus it carries. Using DNA from a termite queen collected from a South African colony in 2011, the researchers put together a high-quality, 1.3 billion-base termite genome assembly. To that, they added transcriptome sequences from queen, king, worker, and soldier termite tissues and metagenomic sequences representing the microbes found in the guts of termites from each caste. Together, this data provides a peek at the metabolic and plant degrading enzymes contributed by the termites themselves, by Termitomyces fungus, and by gut bacteria, which exhibited diminished diversity in the termite queen.

A gene expression study in PNAS implicates alterations in transcriptional regulation in a developmental and neurological condition called Cockayne syndrome, which is inherited in an autosomal recessive manner and was previously thought to stem from DNA repair problems and related genome instability. Researchers from the UK and US performed array-based gene expression profiling on dozens of cell lines derived from individuals with Cockayne syndrome. Their results revealed pronounced shifts in the expression of more than 1,200 genes, even in cell lines without any obvious DNA damage — findings that were verified in follow-up studies in tissue from individuals with the condition and in mouse models of the disease. Consequently, authors of the analysis argue that "dysregulation of gene regulatory networks rather than DNA repair defects may be the main cause of neurological symptoms in [Cockayne syndrome]."

Finally, a team from the US and China describe a microRNA called miR-1174 that's specifically found in the mosquito gut and seems to play a role in the creature's ability to digest and absorb components in a blood meal. The researchers focused in on miR-1174 following a prior study looking at miRNAs found at higher-than-usual levels in the guts of female mosquitoes after consuming blood. Their more detailed analysis of miR-1174 expression and effects of its depletion hint that the female midgut-specific miRNA targets an enzyme called serine hyroxymethyltransferase in Aedes aegypti and A. gambiae mosquitos. In its absence, the study's authors saw diminished absorption of sugar and reduced blood intake into the mosquito gut, prompting downstream problems with everything from proper egg maturation to overall survival.