Bioscience

Major Progress in Research of Information Transmission and Integration in a Model Neural Circuit

Although the response properties of most neurons are, to a large extent, determined by the presynaptic inputs that they receive, comprehensive functional characterization of the presynaptic inputs of a single neuron remains elusive. Toward this goal, a research group led by Prof. Guo Aike of the Institute of Neuroscience, introduced a dual-color calcium imaging approach that simultaneously monitors the responses of a single postsynaptic neuron together with its presynaptic axon terminal inputs in vivo. As a model system, the researchers applied a strategy to the feed-forward connections from the projection neurons (PNs) to the Kenyon cells (KCs) in the mushroom body of Drosophila and functionally mapped essentially all PN inputs for some of the KCs. They found that the output of single KCs could be well predicted by a linear summation of the PN input signals, indicating that excitatory PN inputs play a major role in generating odor-selective responses in KCs. When odors failed to activate KC output, local calcium transients restricted to individual postsynaptic sites could be observed in the KC dendrites. The response amplitudes of the local transients often correlated linearly with the presynaptic response amplitudes, allowing direct assay of the strength of single synaptic sites. Furthermore, they found a scaling relationship between the total number of PN terminals that a single KC received and the average synaptic strength of these PN-KC synapses. Their strategy provides a unique perspective on the process of information transmission and integration in a model neural circuit and may be broadly applicable for the study of the origin of neuronal response properties. This result was achieved by a research group headed by Guo Aike, member of CAS and research professor of the Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences was published on line Proceedings of National Academy of Sciences on July 1st.

Fev Regulates Hematopoietic Stem Cell Development via ERK Signaling

Hematopoiesis and cardiovascular development group led by Prof. Liu Feng, Institute of Zoology, CAS, has demonstrated that a new ETS transcription factor, Fev, plays a pivotal role during hematopoietic stem cell (HSC) development in zebrafish embryos and human cord blood. Knocking down of Fev by antisense morpholinos can attenuate HSC and T cell development in zebrafish. Fev genetic mutant zebrafish generated by TALEN displayed similar phenotypes. Function studies suggest that Fev regulates HSC development through direct regulation of ERK signaling. Transplantation experiments using zebrafish blastula confirmed that Fev acts cell-autonomously. Experiments performed with purified cord blood show that Fev is expressed and functions in primitive HSCs in humans, further supporting its conserved role in higher vertebrates. This provides some insights for new strategies to induce or expand transplantable HSCs in vitro or ex vivo for treatment of hematological diseases. Their work was published in Blood as cover story on July 18, 2013 (Blood 122 (3):367-375).