Oxford, UK. An in vitro fertilization (IVF) test detects chromosome number anomalies (aneuploidy), a finding with longer-term implications for human reproduction studies.

Only a comparatively few oocytes (eggs) per IVF treatment cycle are able to produce a pregnancy because many eggs have chromosomal irregularities. Misidentification can increase the risk of aneuploidy, leading to miscarriage and Down syndrome.

Houghton, MI, USA. Sexual reproduction confers the significant evolutionary advantage of new genetic combinations, strengthening an organism's ability to adapt.

Sexual reproduction can sweep mutations out of the gene pool more quickly by shuffling genetic material with each generation, increasing the likelihood of new genetic combinations that help organisms adapt to their environment. However, there had been no direct empirical evidence to support the advantage of new genetic combinations.

Los Angeles, CA, USA. A large survey of human genetic variation found one genetic variant for every 17 bases, a dramatically higher rate than expected by the investigators.

The procedures used for the study have implications for tracing and understanding non-disease states, as well as the degree to which human variations of any type are common in human populations.

New York, NY, USA. Ninety percent of every mammal's genome is dark matter harboring ancient viral DNA that infected our ancestors from as far back as the age of the dinosaurs.

Scientists have uncovered clues as to how our genomes became riddled with viruses, revealing important new information.

Worcester, MA, USA. A chromosome layer folds into contiguous yarns that harbor groups of genes and regulatory elements, enabling contact for coordinated development work.

This is a new layer in the complex organization of chromosomes, the molecular basis of genetic heredity. Even though chromosomes have remain largely enigmatic since biologist Walther Flemming discovered them in 1882, recent research has begun to unravel some of their mysteries.