Sunday August 20, 2023

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Welcome to a new season of Lab-Fab! I hope you enjoy the show. This season is brought to you by the UK’s Royal Society, in the form of a Wolfson Visiting Fellowship, and by the University of Birmingham’s School of Mathematics, who are hosting me, ably abetted by the same Uni’s School of BioScience. I’ll be collaborating with Prof. Rosemary Dyson (Maths) and grateful to be taking up space in the lab of Dr Florian Busch (BioScience). With that said…

I have just arrived at Birmingham, UK. So far, I have seen neither office nor the bench: By “just” arrived, I mean about 48 hours. So far, everything has been domestic. I would not call it “bliss”, but our flat is light, airy, and quiet, the location is good, and most of appliances work. So bliss-ish. OK, we were locked out of the flat for an hour because of a dodgy key, but that is a story for another time. 

And when I get to office and bench? This year, I will be working on root twisting. Let’s get all the Twisted Sister jokes out of our systems now. Thank you. Roots do twist as they grow; tree trunks do too. The trunk of a tree is twisted by the action of its cambium, a ring of growing tissue that encircles the stem. A root may also have a cambium, if it is a long-lived root, and so might also twist in a similar process to that of the trunk. However despite its familiarity, twist driven by cambium is a story for another person; I’ll be studying the twist produced by the tip of the root.

Sometimes, twisting happens right down at the tip, where the body of the root is created. A cambium adds to an existing stem (or root) but the tip makes the root (or stem) in the first place. Usually a root (and I am going to stop writing ‘or a stem’) grows straight. And by ‘straight’, I mean that lines drawn parallel to the long axis of the root would stay parallel to the long axis. No, they would not be perfectly, i.e., mathematically, parallel: As the root negotiates the soil, going around a stone here or bearing right for a phosphate morsel there, those lines will bend and wiggle. But on average, the lines will run parallel to the root; they will not deviate systematically from their state of parallel-ity. 

But sometimes, the root twists. That means the lines will form helices around the root. Think of a barber’s pole. The barber’s red and blue colors twist presumably to catch the eye of a passing long-haired customer; what is in it for the root? I don’t know. I have heard it said that a twisted root is a more strongly anchored root. Sounds good but equally the twisting could represent a kind of failure. Living up to the general connotation of ‘twisted’ meaning something that is off-kilter, root twisting is often caused by mutation. Still, for me, the “why” is not the issue; instead I am interested in the “how”. 

This year, I am going to try to find out how a root twists. The standard growth operation, the process that produces straight roots, somehow shifts to produce twisting roots. I believe that if I figure out the shift, then I will gain insight into the standard growth process. Thus, I am not really interested in the twist, per se; instead, I am exploiting the twisted state to learn about growth, in general. 

They say science is like cooking; so, here is the recipe for figuring out root twisting. First, define the growth pattern at essentially the level of the cell; after all, it is the cells that grow. Next, define the cellular deployment of the key structural elements: the cellulose microfibrils. Finally, develop a theory that relates the step one and step two. Mix well and bake at 400ºF for 45 minutes. Delicious. I’ll be writing more about each step in subsequent episodes. Stay tuned!