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…).
Bacteria are super smol (~10^2-3X smaller than our cells), so a gut microbiome is only a few hundred grams.
However, these ecosystems burn hot. In mice, gut microbes make up ~1% of their body mass, but can account for ~8% of their energy expenditure (doi.org/10.1093/functi…).
Commensal (benign/beneficial) gut bacteria help shape the host environment. For example, strict anaerobes in the gut help maintain low oxygen levels in order to block competitors that grow aerobically (doi.org/10.1073/pnas.1…). Some of these aerobes are potential pathogens ☠️
We produce a thick mucus layer in our gut (doi.org/10.1073/pnas.1…), which maintains a détente between our gut tissue and our commensals, preventing them from touching directly. The sugars within this mucus can also 'tame' pathogenic microbes (doi.org/10.1038/s41564…).
The gut is a prolific anaerobic bioreactor, which processes food & host metabolites into a plethora of bioactive small molecules that are absorbed into the bloodstream. Up to 30% of the metabolites in various tissues/organs come from our gut microbes (doi.org/10.1038/s41586…).
One of the most exciting aspects of the microbiome is how it influences the nervous system. Bacteria in the gut can regulate neurotransmitter production (doi.org/10.1016/j.cell…) and directly produce certain human neurotransmitters.
Indeed, work done in fruit flies has shown that the microbiome can influence cravings for specific foods (doi.org/10.1038/s41467…)! And many other studies have indicated that microbes can hack host behaviors 🤯
One off-the-wall fact about commensal microbes is that some can physically alter the blood type of red blood cells (doi.org/10.1038/s41564…). Decomposing cadavers can show different blood types in different body sites due to this activity.
Finally, I should say that not all animals need a microbiome (doi.org/10.1093/femsle…). Some would die without one (e.g. cows), while others could care less (e.g. caterpillars). Humans seem to be somewhere in between. We're only beginning to understand how these chimeras work!
Ok, that's a wrap! I hope I've convinced you that this #microbiome 💩 is cool 😎
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?
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.
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.
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/6d93vce4tinyurl.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
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
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!
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…
It's #DBIOtweetorial time! Your host, Wallace Marshall. Welcome to 10 Crazy Things Cells Do. We hope to get you thinking about the complexity of cells + challenges in learning physical principles that underly cell behavior. Let's get started! #EngageDBIO#XtremeCellBiology.
Cells can be really big. Many cells are small, but some are gigantic. Each little "plant" in this picture is a single algal cell, Acetabularia, more than 10 cm long. What determines the size of cells? bmcbiol.biomedcentral.com/articles/10.11…
Cells can walk. You think of cells creeping along on a glass slide, but cells can move in more complex ways. @BEuplotes studies cells that can walk using 14 tiny feet. biorxiv.org/content/10.110…