Nature Genetics pp1122 - 1125

Females do not show greater rates of migration than males' migration at the continental and global scales, according to a study published in the October issue of Nature Genetics. This is contrary to previous studies which have found higher rates of migration amongst females than males, which has largely been attributed to the phenomenon of patrilocality, where women move into mate's residences after marriage.

Michael Hammer and colleagues compared the rates of migration amongst females and males by testing sequence variation on both the maternally (mitochondrial) and paternally (Y chromosome) inherited sequences. The authors found similar rates of variation on both the mitochondrial sequences and Y chromosome. If, as has been previously suggested, there is a skew towards a larger female population size, then this finding suggests females may also have lower migration rates. The survey included 389 individuals from 10 populations spanning Africa, Europe, Asia, and Oceania.

Nature Genetics pp 1061 - 1064

Scientists in Switzerland report in the October issue of Nature Genetics that they have identified a gene that may have facilitated some of the increased cognitive capacities of the human brain. Fabien Burki and Henrik Kaessmann show that a version of the enzyme glutamate dehydrogenase - which is well adapted to function in the brain - was duplicated less than 23 million years ago in the common ancestor to humans and the great apes (chimpanzee, bonobo, gorilla and orangutan).

The original version of the enzyme, GLUD1, is expressed in many tissues, but the duplicated version, GLUD2, is found only in the brain, retina and testis. In the brain, glutamate dehydrogenase is important for recycling the neurotransmitter glutamate, which is involved in signaling between neurons. Since the duplication, GLUD2 has diverged from GLUD1 in such a way that enables its activity in the brain, and Burki and Kaessmann show that these changes were selected for during evolution.

As the birth and evolution of GLUD2 coincided with a period of increased functional complexity of the great ape brain, the authors suggest that it contributed to the increased neurotransmission and enhanced brain function in apes, and ultimately, in humans.

Nature Genetics pp 1090 - 1098

In the October issue of Nature Genetics, Aviv Regev and colleagues report a new tool for understanding the molecular basis of cancer, and present a global map of the genes which are differentially regulated in a wide variety of human cancers.

The authors scan the DNA sequences from 22 tumor types, and identify functionally coexpressed genes (termed modules) that are shared amongst tumors from different human malignancies, as well as those unique to a given type. They show that particular tumors can be well characterized by a relatively small number of these unique modules.

The authors have provided a publicly available search engine based on the model presented, which will allow researchers worldwide to generate an automated module map. The model uses biological knowledge directly, including microarrays of gene expression from tumor samples, as well as clinical annotations.