Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

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· Categories: Biology
What I’ve Learned:

Yersinia pestis: A plague on pretty much ALL the houses, really.
“Yersinia pestis: A plague on pretty much ALL the houses, really.”

Science has helped us to cure a few infectious diseases over the years, like smallpox and polio — and measles, if you live far enough away from Jenny McCarthy. But many dangerous diseases remain, and threaten us all in one way or another. Influenza, for instance. Tuberculosis. Adam Sandler movies.

Also on that list is a name you may not recognize, but which has terrorized the earth for thousands — and humans for hundreds — of years: Yersinia pestis.

That may sound like the name of a Bond villain’s girlfriend, or that animated Disney lady with a grudge against spotted dogs. But it’s actually worse. Much worse.

Yersinia pestis is a species of bacteria, and the disease it causes has been called many things through the centuries. The Plague of Justinian in the 6th century AD. The Black Death in late Middle Ages Europe. Then the Great Plague of Seville, the Great Plague of London, the Russian Plague of 1770-72 and the worldwide Third Pandemic, among many others. At any time, the name changes based on where in the body Yersinia pestis makes its home: pneumonic plague in the lungs, septicemic plague in the blood and bubonic plague in lymph nodes.

Today, we just call it “plague”. Maybe we got lazy with the naming in modern times. I blame Twitter.

No one knew exactly what caused all of these outbreaks until 1894, when Pasteur Institute scientist Alexandre Yersin discovered the culprit bacterium during a plague epidemic in Hong Kong. The species was later named after him; that’s where the Yersinia comes from.

(If the pestis part comes from being a “pest”, that seems like a colossal understatement by whomever is naming these things. A housefly is a pest. Rob Schneider is a pest [who apparently lives too close to Jenny McCarthy]. Yersinia pestis has killed tens of millions of people and once wiped out a third of the European population.

It seems like that rates at least a “Yersinia bothersomeis“. I’m just saying.)

As a bothersome-at-least pathogen, Yersinia pestis has been the subject of much study by modern scientists. Genomes of two of the three known subspecies have been fully sequences, and the genes making these bacteria more virulent than closely-related Yersinia species are well understood. The cycles of infection have been studied, as well — from the fleas harboring bacteria that spread the disease among animals via bites, to rodents like rats and prairie dogs that serve as “reservoir hosts” maintaining bacterial populations, to humans — where Yersinia pestis really gets nasty.

In people, the bacteria survive by following the “best defense is a good offense” strategy. Rather than hiding from our immune system cells, Yersinia pestis meets them head-on. It invades white blood cells, and suppresses the body’s ability to mount an immune response. The bacteria can also kill certain immune cells by injecting proteins directly inside that form pores in the outer membrane, so the insides leak out. Even at a subcellular level, Yersinia pestis plagues are horror movie-level gruesome.

As a final insult, the bacteria often set up shop right in lymph nodes, centers of immune system function. You’d think it was enough to spread all over your body and possibly kill you, but no — Yersinia pestis also wants to rub it in your face.

Luckily, modern science also has a fairly good handle on how to treat the plague. Caught early enough, Yersinia pestis infections respond to antibiotics, and research is ongoing using specific bacterial proteins to make a preventative vaccine.

Still, we’re unlikely to wipe Yersinia pestis completely off the map any time soon. Cases are still reported occasionally today, and recent DNA sequencing performed on material from a 20 million year old fossil flea turned up Miocene Era Yersinia pestis sequence. It seems the world has suffered this “pest” for many, many years and probably will for many, many more to come.

Just like Adam Sandler movies. Sigh.

Image sources: IFLScience (Yersinia pestis micrograph), Wired (Sandler, shocked), Mickey News (Cruella, looking cruel), ETrueHollywoodNonsense (a grinning clueless pesky baboon — and also, an orangutan, I think)

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· Categories: Biology
What I’ve Learned:

Mycoplasma: Small things, which probably also come with small packages.
“Mycoplasma: Small things, which probably also come with small packages.”

In every group, there’s one little guy trying to compensate for his small stature by acting tough and being a royal pain in the ass. In the bacterial world, that’s Mycoplasma.

Mycoplasma is a genus — that is, a group of species — of one-celled microscopic critters, just like all other bacteria. But there are a few important differences. For one thing: size. Even by bacterial standards, mycoplasmas are runty; in fact, they hold the record as the smallest living cells known to science.

It’s true. Most people think it’s Verne Troyer. But no. Mycoplasma.

Besides making them cocky and insufferable, mycoplasmas’ small size creates problems for researchers who study them. These bacteria can’t be seen, even under most microscopes, and wriggle through filters that trap their beefier bacterial cousins.

Another difference is the cell wall — a tough layer outside the cell that provides structure and support. Most bacteria (and fungi and algae and plants) have them; mycoplasma species don’t. That’s highly unusual for a single-celled creature. They’re oozing around barely decent, in nothing but their skimpy cell membranes. Mycoplasmas are the creepy exhibitionist neighbors of the bacterial neighborhood, who never put on pants and refuse to close the blinds.

Sadly, the mycoplasmas’ lack of shame causes more problems than the occasional unwanted peepshow. Many antibiotics — including penicillin — attack bacterial cell walls. Mycosplasmas laugh and shake their scantily-clad bacterial butts at these drugs. So if you catch a mycoplasma infection — they cause atypical pneumonia and pelvic inflammatory disease, among others — you won’t get rid of them with the usual antibiotic suspects. The little bastards actually are tougher than they look.

But mycoplasma species aren’t just compensating for puny size. Besides the cell wall, they have genomes smaller than most any other organism — so small, scientists were able to synthesize the whole thing from scratch and effectively create a “synthetic” bacterial cell using the DNA.

Also, they can’t make any of their own amino acids, and leech cholesterol from whatever they’ve infected to shore up their cell membranes. So in a sense, mycoplasmas are incomplete — dependent on hosts to survive, feeble and literally devolving. Scientists think the cell wall and genetic material were lost from Mycoplasma species after they split off from other bacteria.

Seriously, no wonder they’re a pain in the ass. I wouldn’t be surprised if mycoplasmas all had hair plugs and gold chains and drove teeny little BMWs.

Mycoplasmas are so screwy, they’re a big problem for biologists — even the biologists not trying to study them. Maybe especially the ones not trying to study them.

The issue is, mycoplasma contaminations are very hard to detect and require special tests. Much biological research depends on cell lines and tissue cultures — living cells extracted from humans or animals that can be grown in the lab and tested in various ways. But if mycoplasma is lurking unseen inside those cells, then any test results could be compromised. And it’s estimated that a third or more of the world’s cultures may be contaminated.

All that runty bacterial goop screws up the real science, and no one knows exactly what the results are until the cells are cleaned up and experiments repeated. This costs time, money and — worst of all — graduate student sanity. Those poor lackeys don’t have much to begin with, and mycoplasma infections can shred their last remaining wits. I’ve seen it. It’s tragic.

So beware of the Mycosplasma species. They’re tiny, overcompensating, and seemingly everywhere. They’ll make you sick, drive you crazy and get less evolved every day. In short, mycoplasmas are like an unseen horde of Rob Schneiders, storming into your favorite cells. The horror. Oh, the HORROR.

Actual Science:
MicrobeWiki / Kenyon CollegeMycoplasma
The ScientistOut, damned mycoplasma!
NatureResearchers start up cell with synthetic genome
Journal of the American Medical Association (JAMA)Newly discovered protein helps mycoplasma evade immune response
MIT Technology ReviewHuman genome contaminated with mycoplasma DNA

Image sources: Animal Architecture (synthetic mycoplasma), US Magazine (Verne Troyer), AutoWeb (small penis), Suitably Bored and SodaHead (Schneider horde)

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