Ribose, ribosomes, ribonucleic acid (RNA): none of them have anything to do with ribs. #HematologyTweetstory 20 is about the curious origin of those names, as the world grapples with a dangerous self-replicating #RNA virus. (RNA Image: @ScienceMagazine )/1 
Our story begins thousands of years ago, in the ancient Middle East & North Africa. There was a particular tree - the acacia (Acacia seyal & Acacia senegal) - that exuded a sap that, when hardened, was highly treasured as a binder & gum. (Dripping branch image: Ashwin Baindur.)/2
Since much of the gum from the acacia tree found its way to Europe from Arab-controlled ports, it became known as “gum Arabic” (or “gum sudani”) in Europe. It is still commercially valuable today, but before the modern era it was hugely important, especially in medicines./3
Shakespeare even wrote about this gum in Act V of Othello:
“...one whose subdued eyes,
Albeit unused to the melting mood,
Drops tears as fast as the Arabian trees
Their medicinable gum.”
Weeping tree image is from the 1491 Hortus Sanitatis, which W.S. would have known. /4
“...one whose subdued eyes,
Albeit unused to the melting mood,
Drops tears as fast as the Arabian trees
Their medicinable gum.”
Weeping tree image is from the 1491 Hortus Sanitatis, which W.S. would have known. /4
In the 19th century, chemists learned that gum Arabic is made up primarily of 2 sugars. One component was galactose, so-called since it was also found in milk (γάλακτος = milk sugar in Greek). The other became known as "arabinose", after gum Arabic. (-ose means a saccharide)./5
In 1891, Prof. Emil Fischer and his newly-minted PhD student Oscar Piloty in Würzburg @Uni_WUE synthesized a new 5-carbon monosaccharide they called “ribose”, since it was so similar to arabinose, differing (epimeric) only at the 2' carbon. They had no use for it./6
In 1909, Phoebus Levene (1869-1940) and Walter Jacobs (1883-1967) at @RockefellerUniv found that a form of ribose - D-ribose, rather than the L-ribose Fischer/Piloty had made - was an important constituent of cellular nucleic acids./7
Although this discovery was made in the US & neither Jacobs (American by birth) nor Levene (Lithuanian; immigrated from Russia as a young man) had connections to Germany, their articles were written in German & published in German journals...back then, the language of science. /8
It seems worth noting that until the 1920s, Germany was far ahead of the rest of the world in chemistry, physics and biology. But then they went insane politically (as Einstein warned in this 1922 letter) & subsumed science to ideology. Perhaps there is a lesson somewhere?/9
When first studied in the early 1900s, the chemical and biological differences between nucleic acids (RNA vs DNA) were not clear. They were named after the materials from which they were isolated; RNA was initially known as "yeast nucleic acid"; DNA was "thymus nucleic acid"./10
At the time, "yeast nucleic acid" (RNA) was thought to occur only in plants, "thymus nucleic acid" (DNA) only in animals. In 1933, while studying sea urchin eggs, Jean Brachet suggested: DNA is found in cell nucleus, RNA is present in the cytoplasm. /11
Of course it turned out to be more complex than that, but to a first approximation, Brachet was correct. The field of RNA biology has been particularly fertile; I won’t indulge in scientific hagiography, but >30 people have won RNA-related @NobelPrize: RNA pol., splicing, etc./12
And some people like ribosomal RNA fingerprinting pioneer Carl Woese @Illinois_Alma (depicted) probably should have won one, but didn’t. Woese's discovery of Archaea is nicely described in @DavidQuammen's terrific book "The Tangled Tree", which I can highly recommend./13
Ribosomes were 1st observed in the 1950s by George Palade (Romanian-American; shared 1974 Nobel) using electron microscopy. Richard Roberts named them in 1958; "ribosome" was much better than another proposed option, "ribonucleoprotein particles of the microsome fraction"./14
In November 2019 ribose was even found on a meteorite, giving a boost to the #panspermia hypothesis of the origin of life as well as the idea that life may exist outside of Earth. Very cool, @NASAAstrobio./15
In the mid-20th century, arabinosyl nucleoside analogues were used as chemotherapeutics and antivirals. Thus we have “cytosine arabinoside”, or “Ara-C” - still an essential drug in the treatment of acute myeloid leukemia #AML. The “Ara-“ recalls gum Arabic & the acacia tree./16
For symmetry, I wish I could say that the anti-viral #remdesivir, used for treatment of #COVID19 (awaiting more data), was an arabinoside. But the active metabolite GS-441524 (depicted) is an unrelated adenosine analogue that interferes with viral RNA-dependent RNA polymerase./17
I can remember years ago telling an Arabic-speaking patient from UAE whom I was treating that the medicine he received for #AML had the word “Arab” in it, and ultimately had origins in the Maghreb – he was thrilled. (And more importantly, cured.) We’ll end on that high note!/18
