An article published in the open-access journal PLoS Genetics reports that male and female primates and humans have hundreds of biological differences that are evident in gene expressions in the cerebral cortex. The Uppsala University, Karolinska Institute, and University of Chicago researchers maintain that some of these differences first appeared a very long time ago. Notably, evolution has preserved these differences that indicate particular sex differences in the brain.
Although clear differences between males and females – like average body size, weight, and genitalia design – have been sustained during primate evolution, this new study has analyzed gene expression within the cerebral cortex. This part of the brain is responsible for complex functions in primates, including humans, such as memory, attentiveness, thought processes, and language.
Björn Reinius (Department of Development and Genetics, Uppsala University, Uppsala, Sweden) and colleagues conducted their study by measuring gene expression in the brains of male and female humans, macaques, and marmosets. The researchers took the products of genes (RNA) from each animal’s brain and hybridized them to microarrays that consisted of thousands of DNA clones, coding for thousands of genes. The between-sex analysis required the authors to focus on DNA sequence differences for genes presenting different expression levels.
Co-author Professor Elena Jazin (Uppsala University) specifies that, “Knowledge about gender differences is important for many reasons. For example, this information may be used in the future to calculate medical dosages, as well as for other treatments of diseases or damage to the brain.”
The authors found that, “Genes with conserved sexual gene expression dimorphism in the brain also evolve under more evolutionary constraint, compared with other genes, suggesting that they may have important roles during evolution of sex in primates. Moreover, we found higher evolutionary constrains in the coding regions of female-biased genes as compared to both male-biased and non sex-biased brain expressed genes.” They believe that the insights provided by this study may help explain some of the psychiatric diseases with differences in males and females.
Reinius adds that future studies will be required to answer questions regarding whether these differences in gene expression are functionally significant.
An Evolutionarily Conserved Sexual Signature in the Primate Brain
Reinius B, Saetre P, Leonard JA, Blekhman R, Merino-Martinez R, et al.
PLoS Genetics (2008). 4(6):e1000100.
doi:10.1371/journal.pgen1000100
Click Here to View Article
About PLoS Genetics
PLoS Genetics (http://www.plosgenetics.org) reflects the full breadth and interdisciplinary nature of genetics and genomics research by publishing outstanding original contributions in all areas of biology. All works published in PLoS Genetics are open access. Everything is immediately and freely available online throughout the world subject only to the condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses the Creative Commons Attribution License.
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world’s scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org
Written by: Peter M Crosta