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Optogenetics is a neuroscience method that lets you fire neurons with the flick of a light switch. Neurons are not typically persuaded to fire when light is shined on them, but the expression of light-gated ion channels such as channelrhodopsins (ChRs) makes them light-responsive. When light shines on excitatory channelrhodopsin-expressing neurons, the channelrhodopsins respond by opening and allowing an influx of ions into the neuron which generates an action potential (Figure 1). This light-induced excitation can take place in a tissue culture dish but can also happen in real-time inside a mouse’s brain. 

But the brain is a tricky organ to access, which often forces scientists to use invasive measures to perform in vivo optogenetic experiments. Intracranial injections of AAV are commonly used to deliver channelrhodopsins to the brain. This delivery route concentrates lots of channelrhodopsins in one region of the brain, which is needed since current channelrhodopsins tools have low conductance, but also confines channelrhodopsin activation to a small volume of brain tissue (~1 mm³). Current channelrhodopsins also need high-intensity light for activation which requires implantation of fiber-optic cables into the brain.

This post was contributed by guest blogger, Robert Orr, who recently received a Ph.D. in Biology and Biotechnology from Worcester Polytechnic Institute.

What is RNAi?

The loss-of-function (LOF) experiment functions as the building block of our understanding of complex biological processes. Many tools exist to perturb biological function in a direct or unbiased way at the DNA, RNA, or protein level. The “correct” choice of tool requires careful balancing of the inherent advantages and limitations of any technique in the context of the biological question. For example, while gene knockouts have long been considered the “gold-standard” for LOF studies, the high gene copy number found in plants makes traditional knockouts unattractive from a practical perspective. Therefore, techniques that function downstream of DNA, such as RNA interference, can reversibly exert their effect independent of gene copy number.

Here we are seven months past a worldwide shift to work-from-home and just now realizing that we can’t bide our time and wait for it to be over to work on career skills development. Back in March, we posted these 25 great tips for scientists working at home, and you will still find this useful. Now that we’ve been doing this for almost 6 months, you may be looking for more ways to make sure you are moving forward. Here are a few out-of-the-box ideas that might jump start your learning.

Every few months we highlight a subset of the new plasmids and viral preps in the repository through our hot plasmids articles. These articles provide brief summaries of recent plasmid deposits and we hope they'll make it easier for you to find and use the plasmids you need. If you'd ever like to write about a recent plasmid deposit please sign up here. 

Here's what you'll find in this post:

• Tools for labeling excitatory inhibitory synaptic proteins
• Fluorescent protein system for C. elegans
• Fluorescent timers for studying cell cycle length
• The CRISPR corner
• New from the viral service

This post was contributed by guest blogger, Kaustubh Kishor Jadhav, a Research Assistant at MGMs Institute of Biosciences and Technology.

If you are reading this article then you probably suspect mycoplasma contamination in your cell culture or you are about to begin a new cell culture project. If mycoplasmas are present in your lab, don’t be surprised. They are present in most of the cell culture facilities, tissue culture labs and every cell culturist has to deal with this problem. It is estimated that mycoplasma is responsible for up to 60% of the cell culture contamination (Uphoff, 2002).

Mycoplasmas are considered to be one of the simplest and smallest bacteria. The absence of a rigid cell wall makes them resistant to antibiotics and antibacterial drugs like penicillin and streptomycin. Mycoplasma can pass through filtration methods because of its ability to change shape and the absence of a rigid cell wall. Here, I will cover some of the best ways to tackle mycoplasma contamination before they enter your cell culture and what to do if you encounter mycoplasma contamination.