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An artificial uterus for sharks, and in-utero cannibalism

20 Jan

Sharks give birth to live young. The eggs “hatch” within the mother’s uterus and stay there for almost a year. Scientists have successfully grown and given birth to baby sharks using an artificial uterus. It is basically a complex aquarium, with multiple chambers, filtration systems for bacteria, water exchange systems, and lots of sensors.

Though the artificial uterus is basically to prove a concept at this point, scientists are thinking that it may one day help to increase the dwindling numbers of the grey nurse shark.

More info here.

Though the idea of an artificial uterus is a bit freaky in a Brave New World kind of way, the thing that blows my mind the most about this is just a fact about sharks I learned along the way. Apparently, grey nurse sharks cannibalize their brothers and sisters while still in the womb. There are many eggs that hatch in utero. Their egg sacks run out after about two months. Hungry, the baby sharks survive the rest of the year in utero by eating their brothers and sisters. In the end, only the biggest and strongest shark remains. As if sharks weren’t scary enough.


Transparent crab shell

6 Dec

Scientists in Japan have turned a crab shell completely transparent. They used a variety of chemicals and acids to strip the shell of anything with color: fats, lipids, proteins, etc. What was left was a material called “chitin,” which is a long-chain polymer.

Besides looking really cool, this material has some exciting technological implications. Once ground down, treated with a monomer and polymerized, this clear crab shell dust can then be infused into other polymers to create a material similar to that used in flat panel displays, except that it has a much lower coefficient of thermal expansion. This means that the material can withstand greater heat without expanding to much or breaking down. In fact, it is ten times more stable at high temps than traditional materials like glass-fiber epoxies. This heat resistance allows the material to be molded into shapes, or to be made into bendable screens. This is just one more example of mama-nature showing us how it’s done.

Abstract here. Image courtesy of Royal Society of Chemistry/Kyoto University.

Sense of scale and Saturn’s storm

18 Nov

It’s difficult to comprehend the size of objects when they are very large or very small. Check out this site that gives you a sense of the size of cells, viruses, and other biological bits and bobs (you must be flash enabled).

Also, there are some very cool photos of a giant storm on Saturn here. To be honest, I’m not exactly sure what it means to be a storm on a gaseous planet where there are large-scale currents and violent swirling eddies in the different layers of gas all the time. But the pictures are very cool. It looks just like the experiment you see at science centers where you have a big flat circle full of a colored liquid, and you spin it in different directions to see the chaotic motion.

Extremophiles love volcanoes

19 Oct

You may have learned as a youngin in school that all life gets its energy from the sun, and that it is only the sun that makes life on earth possible. You know… plants use the sun to make energy in the form of sugar, animals eat plants for energy, bigger animals eat those animals for energy, but all life began with the sun. While this is true in many respects, it is not strictly true. There are animals that live where there is no sunlight at all. We call them “extremophiles” because they are animals that survive and thrive in extreme environments.

At the bottom of the ocean where there is no sunlight whatsoever, volcanoes provide the energy that is needed for an extraordinary ecosystem to exist. I’m talking about the mid-oceanic ridge in the middle of the Atlantic Ocean. It is a diverging plate boundary, meaning that it is the boundary of two continental plates that are moving away from each other. It is a volcanically active region. There are fissures in the ground, called hydrothermal vents, that release water that was heated within the earth’s crust near the volcanoes. The conditions here are extreme. The temperature of the water issuing from these vents can be anything from 140 to 860 degrees Farenheit. The high temperature of the vents and high pressure at the bottom of the ocean can cause the water coming out of the vents to be supercritical, meaning that it isn’t a liquid or a gas, but something in between with strange properties.

A special type of bacteria has evolved a way to make energy from the hydrogen sulfide dissolved in the water coming out of the vents. It’s called “chemosynthesis.” There is no light, but life found another way to exist. This bacteria provides the basis for the ecosystem surrounding hydrothermal vents. Tube worms, eye-less crustaceans, snails, shrimp, crabs, octopuses and fish all thrive in this ecosystem, specially adapted to the extreme heat and pressure involved. Tube worms attach to the vents and collect the hydrogen sulfide for the bacteria to eat within them. This ecosystem based on chemosynthesis is extremely foreign to us, and was only fairly recently discovered. It is amazing how life finds a way to exist in the most extreme environments. It does make one wonder what else is out there.

Reptile blood

10 Oct

One of my young readers asked: “Is the blood in reptiles a different color than in insects, or other animals?” Great question!

Insects don’t have blood like you and I. They have no red blood cells to carry oxygen around their bodies like mammals do. Insects absorb the oxygen they need through openings in their exoskeleton. But insects do have something called “hemolymph,” a yellow or greenish goo that is mostly made out of water. The hemolymph takes nutrients around the insect’s body and removes waste. It is also powered by a little heart and performs some immune functions for the insects, so I guess we can call it “blood.” As to color, hemolymph is usually greenish or yellowish. Mosquitos have actual blood in them after they feed, but that is because they ate it. Flies appear sort of reddish after you smash them, but that is because of the pigment in their eyes.

Reptiles have red blood like you and I. I believe most vertebrates have red blood because they use hemoglobin (made of iron) to transport oxygen. Oxygenated blood is bright red, and deoxygenated blood is darker in color. The blood you bleed is always bright red because it becomes oxygenated when it is exposed to air. There are some invertebrates that use a copper compound to transport oxygen, instead of hemoglobin, and their blood is blue-green. Crabs, lobster, shrimp, squid and snails all have blue blood.

Solving puzzles for science

6 Oct

Foldit is an online game where you solve puzzles, but what you’re really doing is folding proteins for scientific research. A protein is a series of amino acids all folded up, and how they’re folded is important. There are many different possible shapes a protein can be folded into because there are so many degrees of freedom (different ways it can be folded). But there is only one stable state for the protein to be in, and it will always end up back in that lowest energy state. The shape of the protein allows it to perform a lock and key function as it will fit with and bind with only certain molecules. Apparently, human pattern recognition and old-fashioned intuition are more effective than computers at figuring out how proteins should be folded. Honestly, the website was a little vague on the precise research goal, but proteins are an essential part of everything that happens in the body from breaking down sugars to power your muscles, to transporting nutrients through your bloodstream. Proteins play a role in the reproduction of the HIV virus inside your body, and in Alzheimer’s Disease, where leftover protein pieces for clumps and interrupt normal brain function. The potential benefits are pretty huge, so if you’re a gamer you should check it out.

Brain-manipulating viruses are not science fiction

21 Sep

It sounds more like a Star Trek episode than scientific fact, but there really are viruses that manipulate their hosts’ behavior to their own benefit. I have been morbidly fascinated by brain-manipulating viruses since I was first introduced to them on the Jungles episode of the Discovery Channel mini-series, Planet Earth. There are many different strains of brain-manipulating viruses, and each has evolved to inhabit a specific type of animal, often insects or insect larvae. Parasites also exhibit such behavior-altering abilities. Behavior-altering parasites have recently been observed in ants, and a bizarre case in rats where the parasite causes the rats to be sexually attracted to cats (because the virus can only reproduce inside a cat’s digestive system).

Gypsy moth caterpillars normally spend their time hiding from birds, and only venture forth at night. Virus-infected caterpillars, however, climb to the top of a tree (something a healthy caterpillar would not do), where they die and liquify, releasing infectious virus bits. The virus uses the caterpillar to carry it to a high place, where it is then able to spread it’s ‘seed’ the furthest possible distance, assisted by wind and rain. Scientists recently discovered the gene that allows the virus to exhibit this behavior (article here). They were able to remove and reinstate the behavior by turning the gene on and off. The gene enables the virus to make a protein that disables a certain hormone of the caterpillar’s. It is all pretty bizarre.