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June 07 Life in Lab Is More Than Doing Experiment "I began to realize that what makes science so distinctive, particularly in an American laboratroy, is not just the experiments themselves, but also the social context, the sense of equality between student and teacher, and the open, ongoing, and brutally frank exchange of ideas and criticism." (Eric R Kandel, In search of memeory, p 106, Norton, 2007) When I read this statement, I totally agree with it, that is important to make us enjoy the life in the lab. Life in a lab is more than just doing experiments. April 03 Optogenetics It is a dream for neuroscientists to control the activity of a specific neuron in a living animal. Now the dream is closer with the emerging filed – optogenetics, which combines the powerful optics and genetics to visualize and stimulate nervous system.
Here are a few pioneers of this field:
March 14 Journal of Visualized Experiments I really like this idea of this journal, Journal of Visualized Experiments. I am glad to know this journal was founded by one of my friend, congratulations to him! And thanks to him, my name was associated with the experiment -- "Mouse Adrenal Chromaffin Cell Isolation". November 25 Systems Biology and Molecular Biology Systems biology is a new but prosperous area, and molecular biology is a relatively mature and sophisticated disipline. Are they really different? How do they contribute to our understanding of biology?
Nearly 3 years ago, Charles Stevens expressed his opinion by illustrating how these two approaches answer two questions: Why our brain have different areas specific for different functions, such as visual area, motion area and somatosensory area? And why are these areas arranged in the way they are, like V1 is always next to V2 and never next to V3 (V1, V2 and V3 are different areas devoted to vision)? Molecuar biology answered these questions by finding the genes that govern the development of those areas, while systems biology explained that it is optimal for the brain to be a computing machine only when it evolved to different areas and arranged in that way. Chuck thought this is not a good example since the answers provided by these two approaches are not unified. But I think it is not because the example, but because these two approaches answered different part of the questions. To me, systems biology is really answering "why", while molecular biology is answering "how", but these two approaches are complimentary and both are important for us to understand biology.
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Organize My Knowledge and my mind. August 22 Geniuses Probably Do Exist I always doubt if there are any real geniuses exist in the world because I have never seen one. But Terence Tao, who was one of the four mathematicians awarded the Fields Medal this year, probably was a real genius if this description were true: "Tao's genius at mathematics began early in life. He started to learn calculus when he was 7, at which age he began high school; by 9 he was already very good at university-level calculus. By 11, he was thriving in international mathematics competitions. Tao, now 31, was 20 when he earned his Ph.D. from Princeton University, and he joined UCLA's faculty that year. UCLA promoted him to full professor at age 24."
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August 05 An Evidence of Neural Circuits Contributing to Behavior Diacetyl is an attractive odorant to the worm C. elegans. Is this attraction behavior due to the odorant receptor or the olfactory neurons? Diacetyl is detected by the receptor ODR-10, which is expressed in the AWA neurons; while the repulsive odorant 2-nonanone is detected by receptor in the AWB neruons. When ODR-10 is transgenically expressed in the AWB neurons, the animal shows repulsive behavior to diacetyl, providing an evidence that neurons contribute to animal's behavior. Ref: Cell. 1997 Oct 17;91(2):161-9. July 23 Modulate Neural Activity in vivo In order to understand how the neural circuits contribute to behavior, we need to elucidate the role of specific type of neurons within that system. Just like we mutate the protein to understand its role, we can also modulate the activity of specific neuron to study its function. Genetic strategies have given great promise to this goal (1). Four years ago, Callaway's group developed an in vitro method that can rapidly and reversibly inactivate neuron activity (2). In this issue of Neuron, the same group furthered their method to in vivo study (3). They use adeno-associated viral vectors to express Drosophila allatostatin receptor (AlstR) in specific neurons (this specificiy is achieved by cell-type specific promoters). This receptor, when binded with its ligand, allatostatin (AL), will open G-protein-mediated inwardly rectifying K+ (GIRK) channels and the increased K+ conductance causes neuronal inactivation. The neural activity can be recovered by washing away the allatostatin. This might be a very useful method to study neural circuits.
Ref: July 19 Is Munc13 a Switch for Neurotransmission? Structure of DNA has revolutionized biology because of its universality. How about the structure of protein? Many proteins have similar domains, but do they have similar functions? Many C2 domains have the Ca-dependent phospholipid binding property. However, here Rizo and his colleagure show that Munc13-1 C2A domain involves in protein interaction and this interaction might function as a switch for neurotransmission. It is relatively easy to know the amino acid sequence of a protein, but it is hard to predict its structure from its sequence, what's more, even we know the structure, the similar structures seem not to have similar function. Protein fulfill its function by interacting with other molecules, so the key question to understand protein function is to understand how it interacts with its targets; and the key to understand interactions is: domain? sequence? or complex environment? The regulated exocytosis might provide an excellent micro-environment to study how different proteins interact and collaborate to fulfill a function.
Ref: July 09 Update My Website Finally, I updated my website, rearranged most part, but not totally finished yet. July 06 Wisker Trimming and Cortex Spine Growth A central belief in neuroscience is that our behavior is the result of neural activity. If this is true, then a change of behavior will result in a change of neural activity, which can be a change either of the circuit structure or of the synaptic transmission. Here Holtmaat et al. demonstrated that wisker trimming (sensory experience change) enhances the spine formation and loss in the cortex (neural circuit structure change). This is the first step that relates functional circuitry to behavior, we still don't know the exact circuit structure and how this stucture contributes to specific behavior.
Circuits Model: whisker-to-barrel pathway. Background of cortical barrel.
Method: long-term in vivo two-photon imaging
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