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APS-DBIO

@ApsDbio

Apr 22, 2021 • 10 tweets • 11 min read • Read on X

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@BioSciRy

It's a beautiful Thursday! Time for a #DBIOtweetorial on bacterial cell division by @BioSciRy and @PetraLevin at the request of the awesome folks at #engageDBIO!

On a first glance, bacterial cell division may seem simple. In reality, it is the culmination of precisely orchestrated interplay between cytoplasmic and extracellular processes. #EngageDBIO #DBIOTweetorial

To divide, bacteria must: grow, replicate and segregate their chromosome, add new cell wall perpendicular to the old cell wall, and separate. That’s a lot of work! #EngageDBIO #DBIOTweetorial

One protein, FtsZ (in magenta below), is the star of bacterial cell division. FtsZ is a tubulin homologue that polymerizes in the presence of GTP to form a platform for the rest of the division machinery. Image courtesy of Jessie Bullock. #EngageDBIO #DBIOTweetorial

Once the cell grows to the proper size and chromosome replication is complete, FtsZ polymerizes into short polymers around the inner circumference of the cell. These polymers treadmill, just like tubulin! #EngageDBIO #DBIOTweetorial

@fleshball

FtsZ treadmilling ensures new cell wall is added evenly at the division site. This figure from Dr. @fleshball and colleagues shows old cell wall in blue and new cross wall labeled first in green and finally red. #EngageDBIO #DBIOTweetorial doi.org/10.1126/scienc…

A cell has reached the right size for division when each relevant division protein is present in the correct *number* at the septum to proceed. Interestingly, this depends on the number of each protein present, not their cellular concentration. #EngageDBIO #DBIOTweetorial

Rather than being directed to the future division site by a mark of some kind, in many bacteria FtsZ is kept *away* from the cell poles and the chromosome by numerous factors that corral the division protein to midcell. #EngageDBIO #DBIOTweetorial

Some aspects of cell division remain unclear. For example, the mechanisms ensuring that the gram-negative outer membrane, which is external to the newly made cross wall, divides along with the rest of cell envelope are not entirely clear. #EngageDBIO #DBIOTweetorial

@JoeLutkenhaus

Accordingly, bacterial cell division is an active field. Some of the folks to follow here on twitter are: @JoeLutkenhaus @goleylab @jiexiao_lab @CWoldringh @_Alex_Bisson_ @junlab_ucsd @ProfLizHarry @GillesvanWezel @seamus_holden @ajlabny @nartimsoole #EngageDBIO #DBIOTweetorial

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More from @ApsDbio

APS-DBIO

@ApsDbio

Oct 7, 2021

@v_madhu

Hello and welcome to this week’s #DBIOTweetorial by Prof. Madhusudhan Venkadesan @v_madhu. Let’s go!

Feet and fins are quite different in their anatomy. But both have to be stiff enough to withstand the forces of propulsion. Are there deeper connections between them?

Paper: dx.doi.org/10.1038/nature…
Video:

All land vertebrates, or tetrapods, evolved from aquatic ancestors over 370 million years ago. So we and all land vertebrates are fish, in a manner of speaking!

Limbs evolved from fins, but the earliest tetrapod probably used a fin to move on land.

Ref: jstor.org/stable/j.ctt16…

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APS-DBIO

@ApsDbio

Aug 5, 2021

@wbialek

Hello, it's a gorgeous Thursday! Time for a #DBIOTweetorial. A special edition this week — an inaugural *Editweetorial* by your host today, Prof. Bill Bialek @wbialek. #DBIOEditweetorial

Biological systems are complicated. If we try to make “realistic” models we are led into a forest of parameters. If we are going to have a theoretical physicist’s understanding of life, we have to find principles that cut through this complexity.

Maybe a #DBIOEditweetorial provides just enough space to summarize different strategies in the search for principles. Links are to papers that illustrate these ideas, and of course are just a sampling. Please respond with your own favorites.

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APS-DBIO

@ApsDbio

Jun 17, 2021

@goleylab

Have you seen images of bacteria and wondered, “How do they form such strange shapes?” or “Why do they all look so different?” Join us for today's #DBIOTweetorial as we dive into how and why bacteria adopt the shapes they do! #EngageDBIO @goleylab @jordanmbarrows

As Kevin Young eloquently put it, “To be brutally honest, few people care that bacteria have different shapes. Which is a shame, because the bacteria seem to care very much.” Check out how diverse bacterial shapes can be! tinyurl.com/6d93vce4 tinyurl.com/uvbtwvs3

Bacterial shape is largely determined by the peptidoglycan (PG) cell wall, a large macromolecule that surrounds cells and provides structure and support. PG is necessary to maintain cell shape - cells burst when treated with drugs that target PG!
tinyurl.com/m4dys6hb

Read 12 tweets

APS-DBIO

@ApsDbio

Jun 10, 2021

@NatashaMhatre

Are the screaming BroodX cicadas driving you nuts? Wonder how such tiny insects even make such a racket? You’ve come to the right place! I study how insects make and hear sound. By the end of this I hope I can show what biophysical marvels they are! #DBIOTweetorial @NatashaMhatre

@drussellpsu

So what is sound? It’s a disturbance in a medium, generated by a moving object. In this cool gif, by @drussellpsu, you can you see a grey bar moving back and forth within a pipe. The air in the pipe is pushed around, and the disturbance within it (sound) travels through the air.

So anything that moves makes a sound?

Yup, pretty much! The world is full of it: the wind shakes leaves, they rustle; tires vibrate because of friction, and they rumble.

But how ‘loud’ the sound is depends on quite a few things!

frontiersin.org/articles/10.33…

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APS-DBIO

@ApsDbio

Jun 3, 2021

@gibbological

It's #DBIOtweetorial time, with your host @gibbological from @isbsci. Today, you'll get some facts about the ~10^13 microbes that call your gut home. By the end, I hope that you'll see yourself as much more than a mere human. You are an ecosystem! #EngageDBIO #microbiome 💩🦠🧑‍🔬

In the womb, we are sterile (obgyn.onlinelibrary.wiley.com/doi/abs/10.111…). At birth, our mothers (and surrounding environment) act as our 'sour-dough starter culture,' inoculating us with hundreds-to-thousands of species. The exact composition of this 'microbiome' is as unique to us as our genome.

Topologically speaking, humans are doughnuts. The entire outside of this doughnut is *covered* in microbes (mostly bacteria). Most of our microbes live in the colon. There are about 3*10^13 human cells and 4*10^13 bacterial cells in the body (doi.org/10.1371/journa…).

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APS-DBIO

@ApsDbio

May 27, 2021

@BhamlaLab

It's #DBIOtweetorial time! Your host is Saad Bhamla @BhamlaLab. Today we'll learn about 10 ultrafast movements in organisms - from single cells to multicellular beasts. We hope to get you thinking engg+bio+physics of extreme movements.
#EngageDBIO #UltrafastOrganisms.

Contrary to common perception, cheetahs and falcons are not the fastest animals. Mantis shrimps for example can use a saddle-shaped spring to hammer at ~100,000 m/s^2. This is so blazing fast, it cavitates surrounding fluid. nature.com/articles/42881…

Trap jaw ants use their spring-loaded jaws to jump at faster acceleration of 10^6 m/s^2 in 0.06 ms. Faster than the blink of an eye or a bullet from a gun !! How to build robots at this scale and speed remains an open challenge. pnas.org/content/103/34…