Science Tidbits for June 29, 2012

How cool are worms? Really cool. Worms are freaking neat. Annelids (the phylum including earthworms, leeches and polychaetes) are just flat out odd sometimes, and odd makes for teachable concepts.

Zombie worms are polycheates that live in the deep ocean, and have a very odd way of eating.

They don’t, not exactly.

They don’t have mouths. They don’t have stomachs, intestines or anuses either, and yet, they eat the bones of dead whales, and are called bone eating worms or osedax, which means bone eating in Latin.

They use a branching anchor with rootlike structures, covered in microvilli, to secrete acid, which breaks down the calcium structure, liberating fats, which are absorbed and then digested by bacteria living in the tissues of the worm. And zombie worms aren’t even the most grossly named of these critters. Behold the bone eating snot flower worm!

So they don’t eat, but do break down bone and absorb food from their surroundings.

It sounds a bit like a fungus, actually. And this can be a great chance for you to talk about how what a normal defining characteristic of a kingdom (ingesting food for Animalia, photosynthesis for Plantae) are sometimes abandoned, but the organism never hops to another kingdom. A ghost orchid that doesn’t photosynthesize is still a plant, existing as a parasite on fungi underground, only poking up to flower on rare occasion. Students often want to think of non-photosynthesizing plants as fungi, and might want to do the same with bone eating worms, but they still have all the other features of their kingdoms. The osedax still doesn’t have cell walls or mycorrhizae like a fungus. It still has closer genetic ties to other polychaetes and annelids than to anything else. The ghost orchid still has cellulose cell walls instead of chitin. It may not have chloroplasts, but it still is a plant. Great chance to have a lesson on phylogenetic trees.

Another topic you can bring up is the use it or lose it concept. Osedax don’t use a digestive tract and don’t need one. The genes for a digestive tract are turned off and over the millions of years since they evolved, the genes probably have become mutated into a non-functional state. It was once assumed that once you go down this tract, you can’t go back, but scientists have found that geckos have gained and lost their adhesive toe pads several times, and some lineages of scorpions have gone from surface to cave dwelling and back, and lost their eyesight and regained it. The longer you don’t use something and it remains unexpressed, the harder it is to reactivate, but it isn’t impossible.

I would really love to see a study of the early development of these worms, especially to see if their larval forms have digestive tracts.

One other cool detail… Osedax have both male and female sexes, but the males live in a larva like state inside the female.

Worms = cool

A new gene in the influenza virus has been discovered. Let me pick up my teeth. Influenza just went from a genome of 10-11 genes to 11-12.

The gene is hidden in the code of another gene, and it appears to limit the severity of the immune response. If the mouse model is correct, when this gene works, the flu symptoms are less severe. If it is mutated, the flu is more severe and is more likely to kill otherwise healthy people.

The gene wasn’t discovered until now because it is found after the main gene on segment three starts. It basically is a second open reading frame (this is the link to the original paper in the journal Science), and is activated by a ribosomal frame shift. (Does this sound like it may be for an undergraduate genetics course? Oh yeah. But don’t be afraid of handing it to a gifted high school student.)

Basically, the gene is transcribed as normal, making the viral mRNA. The mRNA is then translated, and when the ribosome reaches the start of the internal gene, it slips, missing a nucleotide and the rest of the protein is produced according to the internal gene. This is similar to eukaryotic alternative splicing, and is a very cool way to get two genes coded into the space of one.

This produces a protein that represses the genes of the cell, and probably inhibits the cell from putting up the little red flags that tell the immune system that it has been infected. Less immune response, less chance for a cytokine storm, the nightmare scenario for flu.

Misc science goodness:
Neutron star racing across space 
Graphene may make for an efficient way to make salt water into fresh
Nice way to explain the different parts of the electromagnetic spectrum (xrays to visible light to radio waves) and their significance to astronomy
Why does coal become rare in the fossil record around 300 million years ago? Fungus that could break down lignin evolved about that time.
A rare freshwater mussel is facing extinction.
Animals from the Ediacaran period preserved by volcanic ash.

Teach on.


Science Tidbits for June 21 and 22, 2012

Good Morning, Tokyo. I promised tidbits by morning, and it is still morning on the other side of the planet.

Whenever I teach about the cell cycle, I discuss cancer, and when I discuss cancer and the cell cycle, I talk about how some anticancer drugs work in relation to the cell cycle. While my own dissertation work focuses on using cell cycle dependent drugs and making them more effective by tricking the cell into dividing with a second drug, all before it has repaired damage caused by first, I’m always looking for recent work that hits on this topic. This press release talks about using just such a “one two punch” to attack cancer cells. The full paper can be found here, but access is subscription limited. I suppose I’ll be hitting up the University library.

I love talking about flu as an example of… well, lots of things. Mutation rates, genes, viruses, zoonotic pathogens, genetic recombination, etc. One of the things I talk about is how close we are to an H5N1 pandemic. Right now, the H5N1 strains that are being monitored don’t pass from human to human very efficiently, which is one thing that keeps it from running rampant through the population. All it takes is a few small mutations and the virus can pick up the ability to pass from human to human, and it is only a matter of time before just such a mutant strain evolves. Hopefully, by that point in time, we will have universal influenza vaccines ready, or at least have methods approved for rapid vaccine production via cell culture. The chicken egg method is just too slow.

Do you know that the color you call blue is seen in precisely the same way as another person? A wavelength of 460 nm is a specific shade of blue. Do you see the same exact shade as another person? Does your brain interpret in precisely the same way?

We have no good way of knowing if my color blue is the same as yours, since every person has different eyes and different brains. Your brain, when you look around you, is receiving information from the surrounding world from your eyes, transferred along the occular nerves, and is decoding it. As it does this, it produces a simulation from that information. You can’t see some things that are there. You can’t see pigments that reflect in the ultraviolet range, but they are present, and many insects can see them. Illusions and mirages are excellent examples of errors in your interpretation of the world and how it is in reality.

This is especially true if you have certain genes for colorblindness. The “normal” person has three different types of cone cells in their eyes. They have trichromatic vision. These cones detect different ranges of color, and for each type of colorblindness, you lose one of those ranges. Your simulation is reduced pretty significantly for each malfunctioning cone cell type.

It turns out that there aren’t only people that have one fewer cone cell type, but some people have one extra type of cone cell, and are called tetrochromatic.

This is one of those little details that you can toss in to a lecture about vision or sex linked genes (some types of colorblindness are sex linked, and tetrochromatic vision definitely appears to be). I find that these kind of teaching tidbits can be a useful way of keeping students that are at the top of the curve right there, involved. They may already know a decent portion of the material, but if you toss in a few bits of trivia that they haven’t seen before, they pay attention for the new things that they didn’t already know about.

More fun Pollinator Week stuff from Bug Girl. Ignore the Burt’s Bees commercial part of the video, and enjoy the information about how bees are the true masters of interpretive dance, and how they are involved in pollination. Oh, did I mention that it is one of Isabella Rossellini’s wonderful videos about nature? Because it is.

Are you teaching a class about reproduction? Are you teaching a minimally mature class? Then fill them in on the oddities of animal penises (via Discovery News). The duck one is actually kind of useful if you are talking about prezygotic barriers to reproduction as a means of speciation. Ducks have penises and vaginas that can be species specific, which can prevent one species from being able to mate with another.

Ever have a student ask why you get brain freeze when you eat or drink something cold? Here is a nice video explanation.
Oh, and if you haven’t heard that Europe is working on increasing the involvement of girls in STEM (Science Technology Engineering Math) education, then you have missed out on one of the worst PR bungles ever. Why is it bad (other than being painful to watch)?

Sexist imagery decreases the performance of female students on tests in STEM subjects. Nicole (NoisyAstronomer) points out the problems in the campaign and also gives some good examples of what women doing science look like. (If you are on Google+, follow her for great astronomy news and information) Kylie Sturgess at Token Skeptic also has some great examples of women in science and a good takedown of the ad as well (Kylie’s podcast is pretty great, too).

Their examples are what get people interested in science. Normal people doing interesting things. And the great thing about this is that when you show minority groups involved in science, it increases their involvement, and doesn’t discourage people in majority groups. Their functional privilege makes such differences invisible to them. Well, except for the ones that need their privilege reinforced, and require that all discussions be about them.

Have a nice weekend. I’ll be calling people to push poll on evolution.

When does life begin? A scientific perspective

When does life begin?

I was driving back from a Louisville Area Skeptic‘s meetup and saw a billboard saying that a fetus has a heartbeat at 21 days.

Was that correct? More importantly, did it mean anything useful?

It’s not quite correct. Heart cells develop about 20 days after conception, and the fetal “heartbeat” is first detectable at about 22 – 23 days after conception, so 21 days is a bit early. Since pregnancy weeks (gestational age) are counted from the beginning of your last period (or 14 days before conception), we need to add two weeks to the above time-line if we are to use that framework. Let’s stick with time from conception.

Is it an actual heart?

No. It is a small amalgamation of cardiac muscle tissue. Cardiac cells beat rhythmically on their own, and in concert if they are in contact with each other. In the first week after heart cells develop (around 4 weeks post conception), they are a bulge, a tube-like formation. Between six and seven weeks after conception, the heart can pump a blood-like fluid through tubes like blood vessels.

Is that really useful in determining when life begins? Thats the wrong question altogether. The right question is “What is life?”

Life requires certain features. First of which is the capacity to reproduce, and not necessarily sexually. Your body has to replace old or damaged cells, heal wounds, grow. Second, life has to be able to carry information that can be passed on to the next generation of cells. This hereditary information is carried by cells in their DNA. Third, life has to be able to use energy to drive a metabolism. This means making proteins, burning sugars and fats or storing the same, reproducing, etc and to keep those reactions going. Finally, life must be able to respond and interact with its environment in some manner. Bacteria swim towards food, light or away from things that would kill the bacteria. Fungi grow towards food. Plants grow towards a source of light. Even quasi-alive viruses can interact with their environment as they come into contact with the appropriate molecules for their receptors to interact with. Flowing from these four functions of life is the process of evolution by natural selection.

Any one of our cells is alive, but without the whole body, they cannot meaningfully reproduce. Not into a whole new organism, not into a whole new human. You need to combine an egg cell and a sperm cell to form a fertilized egg in order to begin the process of cell division that produces a new human.

Does this mean that life begins at conception? Again, not quite. Sperm cells are alive. Egg cells are alive. Sperm cells and egg cells have all the features of life. Sperm and egg cells combined to form a fertilized egg that can divide.

Egg cells and sperm cells are alive.

Life doesn’t begin at conception, not at least, life as defined by science. Life continues.

When people ask when life begins, they are asking a metaphysical question. When does the soul enter the body?

We can’t use an instrument to detect the presence of a soul, let alone determine the moment of ensoulment. The soul is not a concept that can meaningfully be examined by science, no matter how strongly you believe in it. Until someone develops a device or test that can reliably detect a soul, science can’t consider this as a valid question.

Don’t ask a scientist if you are asking for an answer that helps you win a political or religious argument. The answer you get won’t always be the one you want.