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Showing posts with label margaret atwood. Show all posts
Showing posts with label margaret atwood. Show all posts

Thursday, December 19, 2013

Henry Dawson as the Margaret Atwood of medicine : heterogeneous survival

Margaret Atwood made famous the old quip that  Americans want to leave the wilderness a success, while Canadians are merely grateful to leave it a survivor.

Henry Dawson, a Canadian doctor, encountered this for real when he went to New York to work among American medical scientists who expected him to focus on virulence in bacteria.

These are incredibly tiny , often immobile, beings who yet are successful in attacking their human hosts and frequently even kill them , despite the army of human medical opponents ranged against them.

In the alpha male world of medicine circa 1940 , virulence = success.

But Dawson was more interested in how these tiny beings persisted in surviving with, on and in us  , despite our bodies' best efforts to detect and kill them.

Because virulence is very much a two edged sword for bacteria : it may kill the host and then where do the successful bacteria live ? 

Or it might provoke a counterattack on the virulent bacteria that kills all of them but ignores their non-virulent kin.

Dawson seems to have been agnostic on the whole division between virulent and avirulent : merely seeing endless varieties of sub-strains among his chosen area of focus : oral commensal strep bacteria.

His team (as well as others) gave the different appearing sub strain bacteria colonies letter descriptions : R , S , L , M.

His team members later went on to study others that have been given names instead, such as vegetative/biofilm, dormants and persisters.

R were rough in colony appearance and didn't seem virulent in many species - unlike the smooth looking  S colonies, while the mucoid M were very virulent in some species.

R had normal bacterial walls, but S and M also had extra jelly-like capsules that made them harder to eat by our white blood cells, if they got in our blood system.

To over-simplify , R forms, because they lack a thick jelly cover , do much better at clinging to our throats and surviving long term by being low key and avoiding entering our blood streams.

L forms ,named after the Lister Foundation in London where they were first discovered, are wall-less. 

The strong but flexible wall of a bacteria (a wall beyond the sack like skin that all cells must have to be a cell ) is usually considered the secret to the bacteria world's successful survival as Life's oldest and most widespread form.

So a bacteria without a wall is a real curiosity - it seems to survive in places of calm where the water around it doesn't suddenly get very salty or very un-salty (to describe vital things osmotic as simple as possible ).

Its lack of bacterial wall even fools the human immune system into considering it not a harmful microbe but rather a part of us.

That film of bacteria we can easily feel on our unbrushed teeth is a biofilm .

When it lands on our previously slightly damaged heart valves, it becomes bigger and harder (literally heart valve calculus) often called a vegetative form and in both cases, provides a safe home for various types of bacteria and their sub strains.

We could call them B or V type bacteria.

Dawson started studying them when he started his pioneering use of penicillin to cure vegetative type endocarditis.

Some sub strains, his team members were the very first to discover in 1942, are naturally slow growing and survive antibiotics because they normally only hit bacteria that are actively growing.

These P types are called now called persisters and they make both teeth bacteria type endocarditis and TB truly awful diseases to fully conquer.

Others deep inside the biofilms don't grow at all normally and are called dormant (D type).

They will happily grow when the normal bacteria population closer to the surface of the biofilm have all been killed by antibiotics , leaving more food for the dormants to eat.

Wow : R,S,M.L,V,P,D forms --- where will it all end ?

Who knows?

The point Dawson was trying to make was that bacteria weren't really invaders, seeking only to enter Man to kill him, but extremely tiny creatures to whom a human adult body was literally the same size to them that the Earth is to us.

They saw us merely as home - just as we regard the Earth .

Yes a sometimes comfortable and sometimes hostile home - just as Earth often is to us - and seemingly they survived life's ups and downs by being 'careless' in their eugenic practises, as least as seen by eugenically-minded humans in the 1930s.

There were, in fact, no perfect pure bacteria clones ---- nothing an Aryan superman would recognize as perfection --- instead they shockingly seemed to tolerate all kinds of cripples and defectives in their population.

Because as the environment varied, what was a defect one day (slow growing or no growing, no capsule, no wall) was a means of survival the next day as the formerly virulent fell like ten pins all around them.

Dawson didn't dismiss the 4Fs of the bacteria world as "useless mouths and life unworthy of life" anymore than he later didn't dismiss the 4Fs of the human world either.

Dawson's close examination of how messily but effectively Reality really works proved much more accurate than all the armchair theories of the purist scientists, like Hitler or Einstein....

Monday, April 2, 2012

SMARTEST creature in the world, pound for pound: BACTERIA hands down !

Michael Marshall
No contest !

This morning, I got to wondering about the ratio of the mass of a being's genome to the mass of its body.

You know how Modernist Man is always oozing on and on about the great size of humans and dinosaurs and blue whales, compared to that of the bacteria, as proof of our greater complexity and hence, presumably, of our intelligence.

I was convinced I won't find any information on this ratio genome mass to body mass, because it won't flatter us humans at all.

I was right -- nobody seems to have asked the question.

If someone has - please feel free to correct me in spades.

(And by the by - somebody please sequence the genome of the giant blue whale and compare that mass to its body mass.)

The average bacteria weighs about 1 pico gram and its genome weighs about one thousand of a pico gram, for a ratio of about one thousand to one.

By way of contrast I should say the human genome, purely in terms of number (and hence mass) of basepairs, is about only 1000 times the size of the larger bacteria genomes.

 In addition, the genes of a bacteria make up a far greater total of  its genome than seems to be the case in that of humans, so we actually mightn't have many more genes than the bacteria does.

But the jury is still out - scientists find it hard to believe all the non-protein coding DNA inside of us humans is totally useless baggage.

Now when we weigh the human genome it weights about six pico grams and let us assume that the average human weighs about 60 kilograms (60,000 grams) (132 lbs), just for the ease of the math.

A one thousand to one ratio of genome to body mass should mean that a human genome should weigh 60 grams, not 6 pico grams.

In plain English, the human ratio ratio of genome mass to body mass is one to a trillion.

That is a ratio one billion times worse than that of the bacteria.

We humans, compared to bacteria, have big bodies but with comparatively small 'genome' brains.

Yes the organ we humans call a brain is very big, in ratio to our body weight, but the giant sulfur bacteria might considering it just another vacuole, only this time holding memories instead of sulfur.

To them, perhaps, the 'real' brain is the genome, because it allows a being to do more different things, rather than just doing a few things extraordinarily well as in the case of the human brain.

Good point - we have a K-selected genome - much more successful than the bacteria's in stable times.

Their genome, by contrast, is an r-selected genome - much more flexible than ours when times get tough and survival not success, is the key.

Think of it as the Margaret Atwood Law of Nature ( you might wanna look up her classic book called Survival to see what I mean ....)