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This Week in Science: Jul 9, 2010

In this week's issue of Science, research led by investigators at the Department of Energy's Joint Genome Institute examines the organismal complexity of the multicellular green alga Volvox carteri. Simon Prochnik et al. sequenced the Volvox genome to 11.1-fold coverage using a whole-genome shotgun approach; when compared to Chlamydomonas reinhardtii, its unicellular relative, the team found that "the two species have similar protein-coding potentials and few species-specific protein-coding gene predictions." The authors suggest that "increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity."

In an accompanying news piece, Elizabeth Pennisi writes that "comparison between the genomes of the 2000-cell Volvox carteri and a single-celled green alga, Chlamydomonas reinhardtii, has revealed surprisingly few differences in their gene makeup." Additional research teams have shown similar results. Nicole King at the University of California, Berkeley, and her colleagues demonstrated that the genomes of a single-celled choanoflagellate and several animals were similar. King et al. concluded that "that part of the tree of life arose not so much from new genes but from a shuffling and recombining of existing genes and parts of genes," Pennisi writes.

A paper published online in advance this week, detailing the work of Stanford University researchers and their colleagues, shows that the lincRNA HOTAIR acts as a modular scaffold "for at least two distinct histone modification complexes." Specifically, the team writes, HOTAIR tethers PRC2 and the LSD1/CoREST/REST complex, allowing for the "RNA-mediated assembly of PRC2 and LSD1 to chromatin for coupled histone H3 lysine 27 methylation and lysine 4 demethylation."

In another research article published online in advance, Christopher Gregg and his colleagues at Harvard University and Illumina report their "high-resolution analysis of parent-of-origin allelic expression in the mouse brain." By characterizing genome-wide imprinting in the mouse embryonic and adult brains, the team found "a preferential maternal contribution to gene expression in the developing brain and a major paternal contribution in the adult brain." In a related report, Gregg et al. write that "parent-of-origin effects thus provide new avenues for investigation of sexual dimorphism in brain function and disease."

The Scan

Cell Atlas of Human Lung Development Gives View of Developing Airway

Researchers have generated a cell atlas of human lung development, which they report in Cell.

Study Finds Costs of Genome Sequencing May Limit Utility in Routine Care

Researchers report in the European Journal of Human Genetics that genome sequencing for rare disease diagnoses currently has similar benefits as less expensive exome analysis.

Study Suggests Nursing Mother's Diet Can Impact Offspring's Gut Microbiome

A new Cell Host and Microbe paper finds that mice whose mothers were fed a low-fiber diet during nursing experience lasting microbiota dysbiosis and increased obesity.

Study Links Genetic Risk for ADHD With Alzheimer's Disease

A higher polygenic risk score for attention-deficit/hyperactivity disorder is also linked to cognitive decline and Alzheimer's disease, a new study in Molecular Psychiatry finds.