Skip to main content
Premium Trial:

Request an Annual Quote

This Week in PNAS: Aug 20, 2013

In a study slated to appear in the early, online edition of the Proceedings of the National Academy of Sciences, a Taiwan-led team introduces JR-Assembler, a genome assembler named for the jumping extension and read remapping that it uses to do de novo assembly of large genomes. In addition to describing their assembler strategy and assessing its assembly statistics when dealing with sequences from various species, the researchers used simulated data to look at the computer memory use and processing time of the assembler, which relies on so-called extension-based graphs rather than de Bruijn graphs.

Inherited compound mutations affecting the helicase gene RTEL1 can lead to a premature telomere-shortening condition called Hoyeraal-Hreidarsson syndrome, or HHS, according to a study by researchers in the US, Israel, and France. The group started by doing whole-exome sequencing of two members of a family affected by HHS, a condition known for causing developmental and bone marrow problems, immunodeficiency, and more. When they analyzed these protein-coding sequencing, the researchers homed in on compound heterozygous mutations in RTEL1 that were ultimately detected in four HHS-affected siblings from that family. Their cell line experiments supported the notion that RTEL1 contributes to telomere protection and elongation, with wild type versions of the gene bolstering telomere lengths in cells from individuals with HHS.

Indiana University's Michael Lynch and colleagues describe findings from a population-based genome sequencing study of Daphnia pulex, a tiny crustacean species sometimes called the water flea. By sequencing 11 individuals from a sometimes-sexual D. pulex genotype and another 11 individuals from an exclusively asexual D. pulex genotype, the team determined that obligated asexuality arose relatively recently in D. pulex — apparently after mixing with members of a closely related species called D. pulicaria. The study's authors also saw signs that the asexual individuals were more apt to have loss of heterozygosity in their genomes than they were to have a slew of new mutations.