Microbiology | Petri Dish Talk

Tag Archives: Microbiology

May 30, 2011 · 9:14 pm

Feed Your Head – Aβ, Tau & APOE

Fig 1: Pathology of AD showing plaques and tangles.

Some would say a soul is the collective memories and personality traits of an individual. So, what is left if those memories and traits are erased? You and I might be far from old and senile (well I’m not old). But you know someone near & dear to you, who will have to deal with this existential crisis in their golden years. Alzheimer’s disease currently has two culprits, Beta amyloid (Aβ) which can form plaques on the brain and Tau protein, whose over expression can cause neurons to tangle up (NFT).

These pathologies appear to be affected by the APOE gene, certain variations of which are now recognized as dead-ringers for Alzheimer’s. The mechanism however is still very much in the process of being understood. More so, when considering the role of Tau.

Fig 2: Constant expression of plaque causing Aβ with varying levels of Tau shows little difference in pathology. Plaques and tangles remain present. Thus deletion or over expression of Tau is not enough to prevent AD pathology.

Although the signs of Alzheimer’s on a cellular level remained steady while playing with the knobs of Tau expression, the authors did find a difference is the cell & organism survivability. Hypothesizing that Tau helps the neuron deal with excitotoxicity, the damage to nerve cells through stimulation.

Don’t lose hope, although it’s difficult to get a full picture, we may have enough glimpses to make a clinical difference. Eventhough, we don’t quite understand the role between APOE, lipoproteins and Alzheimer’s pathology, on a higher symbolic level APOE is a great predictor of who is at risk for AD and sometimes even when. Best move for now is probably just to get your parents genotyped and planning active mental lifestyles for them, there should be a fix by the time I’m grey.

Citations: Reducing endogenous tau ameliorates amyloid beta-induced deficits in an Alzheimer’s disease mouse model by Roberson, et al.

The Polymerase Chain Reaction, A Microcosm

Creating a new life-form is an awe-inspiring experience. Writing DNA like a mere sentence and watching creation unfold in the mechanism of life is both breathtaking and humbling. None of this would be possible without the Polymerase Chain Reaction (PCR). A simple process where all the ingredients for DNA: a teaspoon of reagents, a pinch of polymerase enzyme and a handful of the “letters” that make up our genetic code are thrown into the oven, literally, well a very accurate oven that can step temperatures rather quickly. Within hours the sentence you had written out on a computer screen, is now molecules floating around in a tiny tube ready to be put into a cell, which will read the instructions and attempt to build or act accordingly. Using this simple idea the human race has been handed over the keys to the Build a Life Workshop, however this simple process often goes without scrutiny, without improvement.

Basic Principles of PCR

Much of the drug discovery in both academia and industry is now focused on protein mechanics. How does this receptor behave? What buttons turn this enzyme on and off? Focusing on protein structure and mechanism often makes PCR a boring chore that most researchers have to grudgingly get past before they can get to the interesting part. As a result, the basic process of PCR has remained the same for decades. I literally remember when a P.I. gave me a paper from 1985 to look up what settings I should use for my reaction. All this wouldn’t be a problem, except people are often wasting weeks to months trying to get the right PCR outcomes. At the root of the problem & the solution is information. PCR is a “black box” process, in that you throw all the ingredients together turn on the machine and hope that all the right molecules will bump into each other at the right times. Traditionally, it has been a exasperating trial & error based system. Now however, information technology has given a glimpse of a solution and a way to move forward to the next chapter in the development of this life-science staple.