Česká Genetická Banka

NATURE: 31. 8. - 6. 9. 2012

ENCODE: The human encyclopaedia

"First they sequenced it. Now they have surveyed its hinterlands. But no one knows how much more information the human genome holds, or when to stop looking for it.

Ewan Birney would like to create a printout of all the genomic data that he and his collaborators have been collecting for the past five years as part of ENCODE, the Encyclopedia of DNA Elements. Finding a place to put it would be a challenge, however. Even if it contained 1,000 base pairs per square centimetre, the printout would stretch 16 metres high and at least 30 kilometres long."

http://www.nature.com/news/encode-the-human-encyclopaedia-1.11312

Neuronal circuitry mechanism regulating adult quiescent neural stem-cell fate decision

"Adult neurogenesis arises from neural stem cells within specialized niches1, 2, 3. Neuronal activity and experience, presumably acting on this local niche, regulate multiple stages of adult neurogenesis, from neural progenitor proliferation to new neuron maturation, synaptic integration and survival1, 3. It is unknown whether local neuronal circuitry has a direct impact on adult neural stem cells. Here we show that, in the adult mouse hippocampus, nestin-expressing radial glia-like quiescent neural stem cells4, 5, 6, 7, 8, 9 (RGLs) respond tonically to the neurotransmitter γ-aminobutyric acid (GABA) by means of γ2-subunit-containing GABAA receptors. Clonal analysis9 of individual RGLs revealed a rapid exit from quiescence and enhanced symmetrical self-renewal after conditional deletion of γ2. RGLs are in close proximity to terminals expressing 67-kDa glutamic acid decarboxylase (GAD67) of parvalbumin-expressing (PV+) interneurons and respond tonically to GABA released from these neurons. Functionally, optogenetic control of the activity of dentate PV+ interneurons, but not that of somatostatin-expressing or vasoactive intestinal polypeptide (VIP)-expressing interneurons, can dictate the RGL choice between quiescence and activation. Furthermore, PV+ interneuron activation restores RGL quiescence after social isolation, an experience that induces RGL activation and symmetrical division8. Our study identifies a niche cell–signal–receptor trio and a local circuitry mechanism that control the activation and self-renewal mode of quiescent adult neural stem cells in response to neuronal activity and experience."

http://www.nature.com/nature/journal/v489/n7414/full/nature11306.html

Bioethics: Tighten up Japan's stem-cell practices

"Japan has bioethical regulations and clinical guidelines in place for experimental stem-cell therapies and for stem-cell-based pharmaceuticals. As a forensic pathologist who has worked on a patient who died after mesenchymal stem-cell therapy in Japan, I am aware that other patients receiving this treatment have developed serious and even fatal…"

http://www.nature.com/nature/journal/v489/n7414/full/489033c.html