How the human brain and human cognitive abilities evolved in less than six million years has long puzzled scientists. A new study conducted by scientists in China and Germany, and published December 6 in the online, open-access journal PLoS Biology, now provides a possible explanation by showing that activity levels of genes in the human brain during development changed substantially compared to chimpanzees and macaques. What’s more, these changes might be caused by a handful of key regulatory microRNAs.
The authors studied gene activity in human, chimpanzee and macaque brains across their lifetimes. Starting from newborns, they investigated two brain regions; the cerebellum, which is responsible for motor activity, and the prefrontal cortex, which has roles in more complex behavior such as social interactions or abstract thinking. They first studied the simple gene activity differences between species that are seen at all ages. Although many genes show such simple differences, there was no disparity in numbers of these differences between the human and the chimpanzee evolutionary lineages. Moreover, most of these differences were observed in [click to continue…]
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Researchers at Heidelberg University used a combination of expression profiling of miRNAs and subsequent functional inhibitory screening in primary hippocampal neurons to identify miRNAs in the synaptodendritic compartment that function during synaptic development. MicroRNA microarrays identified ten mature miRNAs that were enriched and four mature miRNAs that were strongly depleted in synaptosomes compared with whole forebrain. Northern blot analysis on selected miRNAs confirmed the microarray results. Subsequent functional screening identified miR-138 as a negative regulator of dendritic spine size and revealed that mRNA encoding acyl-protein thioesterase 1 (APT1) is a miR-138 target in neurons.
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