In the genome’s “dark matter,” a narrow ray of insight.

A small discovery penetrates the mysterious “dark matter” in the 95% of the human genome that doesn’t code for proteins.  It reveals a counterpart of the protein coding machinery that operates in the “non-dark” 5%.  The 95%’s machinery seems to use some of the same gears and pulleys as does the 5%’s better-understood machinery.  This is a minuscule narrowing of an embarrassingly vast darkness.   Continue reading

Human brain cells alive in mouse brains.

[This Truth from Error post first appeared in Scientific American, May 9, 2013.  Link:  http://bit.ly/ZM3CTT]

Into brains of newborn mice, researchers implanted human “progenitor cells.”  These mature into a type of brain cell called astrocytes (see below).  They grew into human astrocytes, crowding out mouse astrocytes.  The mouse brains became chimeras of human and mouse, with the workhorse mouse brain cells – neurons – nurtured by billions of human astrocytes.  Continue reading

An antibiotic that resistant microbes can’t defeat.

The dreaded methicillin-resistant bacteria that increasingly imperil hospital patients, do not defeat it.   Nor can tuberculosis bacteria.

This antibiotic is not new.  It is in fact natural, and probably a few thousand years old.  Nor is it rare:  it’s found in human sweat.  What is new is that researchers have revealed the structure of this undefeated weapon, and also how it kills a bacterium in one ten-thousandth of a second.  Continue reading

Astonishing consequence of 100 trillion microbes inhabiting healthy guts.

Maybe it’s not surprising that digestion and nutrient metabolism is affected by a human’s 100 trillion gut microbes.

But that physical development of a mammal’s body is altered by changes in gut microbes, this is astonishing.

Just discovered:  at puberty, gut microbe populations shift in male and female animals.  Before puberty, they’re similar.  Gut microbe shifts appear to drive male/female differences in post-puberty sex hormone production.  Continue reading

Eyes’ intricate mechanics: another ray of light

Vision, being familiar, can seem ordinary.  Animals of all sorts do it.  How remarkable can something universal be?

But shake off sleepy familiarity and amazement re-awakes.  What, exactly, happens in a retina cell when it absorbs a photon of light?  How, from a fertilized egg, do 100 million retina cells acquire a structure that sends electrical flickers to the brain?  Continue reading

That “junk” DNA: Life gets even more complicated.

Discovery of DNA’s helix structure in 1953 stoked enthusiasm that life’s secret would be soon revealed. The secret would be a chemical one, for complementarity of DNA’s four bases (in the helix ladder’s rungs) suggested a “code” in the molecule. Perhaps it’s like the Morse code, Francis Crick suggested to Sydney Brenner, where two “letters” – dot and dash – translate all written language. Might DNA’s four bases – A, G, C, T — translate all molecules active in life?

It turned out to be more complicated. Continue reading

Another mystery of heredity dispelled.

Nearly 60 years have passed since the Crick-Watson discovery of DNA’s helix structure.  “It has not escaped our notice,” they declared in the short Nature article announcing the breakthrough, that the structure implied an elegant mechanism of heredity. DNA replicates itself – that’s the mechanism – but with such complexity that many of its deeds remain concealed despite decades of research.

A couple of them are a little clearer, today.  Continue reading