Do Bacteria Have Bacteria?

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Drew Smith:

Do bacteria have bacteria? Yes.

We know that bacteria range in size from 0.2 micrometers to nearly one millimeter. That’s more than a thousand-fold difference, easily enough to accommodate a small bacterium inside a larger one.

Nothing forbids bacteria from invading other bacteria, and in biology, that which is not forbidden is inevitable.

We have at least one example: Like many mealybugs, Planococcus citri has a bacterial endosymbiont, in this case the β-proteobacterium Tremblaya princeps. And this endosymbiont in turn has the γ-proteobacterium Moranella endobia living inside it. See for yourself:

Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)
Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)

I don’t know of examples of free-living bacteria hosting other bacteria within them, but that reflects either my ignorance or the likelihood that we haven’t looked hard enough for them. I’m sure they are out there.

Most (not all) scientists studying the origin of eukaryotic cells believe that they are descended from Archaea.

All scientists accept that the mitochondria which live inside eukaryotic cells are descendants of invasive alpha-proteobacteria. What’s not clear is whether archeal cells became eukaryotic in nature—that is, acquired internal membranes and transport systems—before or after acquiring mitochondria. The two scenarios can be sketched out like this:


The two hypotheses on the origin of eukaryotes:

(A) Archaezoan hypothesis.

(B) Symbiotic hypothesis.

The shapes within the eukaryotic cell denote the nucleus, the endomembrane system, and the cytoskeleton. The irregular gray shape denotes a putative wall-less archaeon that could have been the host of the alpha-proteobacterial endosymbiont, whereas the oblong red shape denotes a typical archaeon with a cell wall. A: archaea; B: bacteria; E: eukaryote; LUCA: last universal common ancestor of cellular life forms; LECA: last eukaryotic common ancestor; E-arch: putative archaezoan (primitive amitochondrial eukaryote); E-mit: primitive mitochondrial eukaryote; alpha:alpha-proteobacterium, ancestor of the mitochondrion.

The Archaezoan hypothesis has been given a bit of a boost by the discovery of Lokiarcheota. This complex Archaean has genes for phagocytosis, intracellular membrane formation and intracellular transport and signaling—hallmark activities of eukaryotic cells. The Lokiarcheotan genes are clearly related to eukaryotic genes, indicating a common origin.

Bacteria-within-bacteria is not only not a crazy idea, it probably accounts for the origin of Eucarya, and thus our own species.

We don’t know how common this arrangement is—we mostly study bacteria these days by sequencing their DNA. This is great for detecting uncultivatable species (which are 99 percent of them), but doesn’t tell us whether they are free-living or are some kind of symbiont. For that, someone would have to spend a lot of time prepping environmental samples for close examination by microscopic methods, a tedious project indeed. But one well worth doing, as it may shed more light on the history of life—which is often a history of conflict turned to cooperation. That’s a story which never gets old or stale.

This post originally appeared on Quora. Click here to view.

Why Are the Academy Awards Statuettes Called Oscars?

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Getty Images

In 2013, the Academy Awards were officially rebranded as simply The Oscars, after the famed statuette that winners receive. "We're rebranding it," Oscar show co-producer Neil Meron told The Wrap at the time. "We're not calling it 'the 85th annual Academy Awards,' which keeps it mired somewhat in a musty way. It's called 'The Oscars.'" But how did the statuette get that nickname in the first place?

The popular theory is that the nickname for the Academy Award of Merit (as the statuette is officially known) was coined by Academy Award librarian and future Director of the Academy of Motion Picture Arts and Sciences Margaret Herrick. The story goes that when Herrick first saw the statue in 1931, she said that it looked like her Uncle Oscar. According to Emanuel Levy, author of All About Oscar: The History and Politics of the Academy Awards, columnist Sidney Skolsky was there when Herrick said this and would later write that, “Employees have affectionately dubbed their famous statuette ‘Oscar.’”

While the first documented use of “Oscar” as the nickname for the statuette was made by Skolsky—in a 1934 New York Daily News article—there doesn’t seem to be any evidence that Skolsky was actually responsible for the above quote. Skolsky, in his 1975 memoir Don’t Get Me Wrong, I Love Hollywood, claimed he first used the nickname referencing a classic vaudeville joke line, “Will you have a cigar, Oscar?” in an attempt to mock the Academy Awards:

"It was my first Academy Awards night when I gave the gold statuette a name. I wasn’t trying to make it legitimate. The snobbery of that particular Academy Award annoyed me. I wanted to make the gold statuette human. ... It was twelve thirty when I finally arrived at the Western Union office on Wilcox to write and file my story. I had listened to Academy, industry, and acceptance talk since seven thirty ... There I was with my notes, a typewriter, blank paper, and that Chandler feeling.

You know how people can rub you the wrong way. The word was a crowd of people. I’d show them, acting so high and mighty about their prize. I’d give it a name. A name that would erase their phony dignity. I needed the magic name fast. But fast! I remembered the vaudeville shows I’d seen. The comedians having fun with the orchestra leader in the pit would say, “Will you have a cigar, Oscar?” The orchestra leader reached for it; the comedians backed away, making a comical remark. The audience laughed at Oscar. I started hitting the keys ...

“THE ACADEMY awards met with the approval of Hollywood, there being practically no dissension … The Academy went out of its way to make the results honest and announced that balloting would continue until 8:00 o’clock of the banquet evening … Then many players arrive late and demanded the right to vote … So voting continued until 10 o’clock or for two hours after the ballot boxes were supposed to be closed … It was King Vidor who said: “This year the election is on the level” … Which caused every one to comment about the other years … Although Katharine Hepburn wasn’t present to receive her Oscar, her constant companion and the gal she resides with in Hollywood, Laura Harding, was there to hear Hepburn get a round of applause for a change…”

During the next year of columns, whenever referring to the Academy Award, I used the word 'Oscar.' In a few years, Oscar was the accepted name. It proved to be the magic name."

"Mouse's Return," a September 11, 1939 article in TIME magazine, seems to back up Skolsky’s above claim, stating:

"This week Sidney Skolsky joined the growing stable of writers that Publisher George Backer is assembling for his New York Post. Hollywood thought Publisher Backer had picked the right horse, for Skolsky is one of the ablest columnists in the business (he originated the term “Oscar” for Academy Awards) and by far the most popular …"

Though Skolsky has actual evidence to back his claim, his assertion that he coined the nickname is still slightly in doubt. Many claim that during Walt Disney’s Academy Award acceptance speech for Three Little Pigs in 1934—the same year Skolsky first covered the Awards—Disney referred to the statuette his little "Oscar," which was supposedly an already well-established nickname for it within the industry. The term Oscar was commonly used as a mocking nickname for the Academy Award (as Skolsky claims he used it), but in this theory, Walt Disney was supposedly the first in the industry to publicly use the name in a positive light.

Perhaps Herrick really did think the statuette resembled her uncle. Or maybe Skolsky really did come up with the moniker (whether he did or not, he certainly helped popularize it). In the end, nobody really knows why the Academy Award statuette is called an Oscar.

The idea for the design of the Academy Award statuette was thought up by MGM director Cedric Gibbons. His idea was to have a knight gripping a sword while standing on a film reel. Sculptor George Stanley was then hired to create the actual statuette based on this design idea. The first Academy Awards ceremony was held on May 16, 1929 in the Blossom Room of Hollywood's Roosevelt Hotel. The nickname Oscar wasn’t officially adopted for the statuette by the Academy until 1939.

Incidentally, the Academy states that the five spokes on the film reel the knight is standing on signify the original five branches of the Academy: writers, directors, actors, producers, and technicians.

Daven Hiskey runs the wildly popular interesting fact website Today I Found Out. To subscribe to his “Daily Knowledge” newsletter, click here.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article originally appeared in 2013.

Why Do Bats Hang Upside Down?

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iStock.com/CraigRJD

Stefan Pociask:

The age-old question of upside down bats. Yes, it is awfully weird that there is an animal—a mammal even—that hangs upside down. Sure, some monkeys do it when they're just monkeying around. And a few other tree climbers, like margays, hang upside down if they are reaching for something or—again, like the margay cat—may actually even hunt that way ... But bats are the only animals that actually spend most of their time hanging upside down: feeding this way, raising their young this way, and, yes, sleeping or roosting this way.

There is actually a very good and sensible reason why they do this: They have to hang upside down so that they can fly.

First off, we have to acknowledge that bats are not birds, nor are they insects. These are the other two animals that have true powered flight (as opposed to gliding). The difference between bat flight and bird or insect flight is weight—specifically, the ratio of weight to lift-capacity of the wings. If you walk up to a bird or insect, most species will be able to fly right up into the air from a motionless position, and do it quickly.

Bats, on the other hand (or, other wing), can’t do that. They have a lot of difficulty taking off from the ground (not that they can’t do it ... it’s just more difficult). Insects and birds often actually jump into the air to give them a start in the right direction, then their powerful wings take them up, up, and away.

Birds have hollow bones; bats don’t. Insects are made of lightweight chitin or soft, light tissue; bats aren’t. And bats don’t have what you could call "powerful" wings. These amazing creatures are mammals, after all. The only flying mammals. Nature found a way to evolve such an unlikely thing as a flying mammal, so some compromises had to be made. Bats, once airborne, manage perfectly well in the air, and can literally fly circles around most birds in flight. The problem is in first getting off the ground.

To compensate for the extra weight that mammals must have, to compensate for the problem of getting off the ground, evolution found another way for bats to transition from being motionless to immediately being able to fly when necessary. Evolution said, “How about if we drop them from above? That way they are immediately in the air, and all they need to do is start flapping."

It was a great idea, as it turns out. Except bat feet aren’t any good for perching on a branch. They are mammals, not birds, so their musculature, their bones, and their tendons are set up in a completely different way. When a bird squats down on a branch, their tendons actually lock their toes into an even tighter grip on the perch. It happens automatically. That’s part of being a bird, and is universal. That’s why they don’t fall off in their sleep.

Bats, as mammals, are set up differently. Therefore, to compensate for that fact, nature said, “How about if we have them hang upside down? That way, their tendons will actually pull their toes closed, just like a bird does from the opposite direction.” So that’s what evolved. Bats hang from the bottom of something, and all they have to do is "let go" and they are instantly flying. In fact, with this gravity-assist method, they can achieve instant flight even faster than birds, who have to work against gravity.

Side note: In case you were wondering how bats poop and pee while upside down ... First off, pooping is no big deal. Bat poop looks like tiny grains of rice; if they are hanging, it just falls to the floor of the bat cave as guano. Pee, however ... well, they have that covered too. They just “hold it” until they are flying.

So there you go. Bats sleep hanging upside down because they are mammals and can’t take off into the air like birds can (at least not without difficulty). But, if they're hanging, all they do is let go.

Makes total sense, right?

Now, having said all that about upside down bats, I must mention the following: Not all of the 1240-plus species of bats do hang upside down. There are exceptions—about six of them, within two different families. One is in South America (Thyropteridae) and the other is in Madagascar (Myzopodidae). The Myzopodidae, which includes just one species, is exceedingly rare.

So it turns out that these bats roost inside the tubes of young, unfurled banana leaves and other similar large leaves. When they attach themselves to the inside of this rolled leaf, they do it head-up. The problem with living inside of rolled-up leaves is that within a few days, these leaves will continue growing, and eventually open up. Whenever that happens, the whole group of bats has to pick up and move to another home. Over and over again. All six of these species of rare bats have a suction cup on each wrist and ankle, and they use these to attach to the smooth surface of the inside of the leaf tube. Evolution: the more you learn, the more amazing it becomes.

This post originally appeared on Quora. Click here to view.

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