Human Egg Candling?

A while back on my personal blog I lamented our lack of ability to look at the chromosomes of an egg before it was fertilized. I spun an elaborate fantasy about a noninvasive human egg candling procedure that would tell if a particular egg might have some kind of chromosomal aberration (like Down's Syndrome).

Well, my fantasy remains pretty outlandish, but it turns out that there is a way to look at the genetic make-up of the egg before it is fertilized. I just wanted to make sure it had the proper number and right kinds of chromosomes but it can also be used to look into more specific things. The main reason it is used is to make sure that the egg is viable before implantation. This can cut back on the number of embryos they have to implant after in vitro fertilization in the hopes of having a healthy baby and hopefully, reduce the number of women who go from not having any baby at all to having four all at once.

The way it is done is to take the polar body out of the egg and do genetic testing on it. You might remember that in the process of reducing the number of chromosomes to half that of a regular cell, the egg produces these little things called polar bodies. Normally they disintegrate after the egg is fertilized but they contain the mirror half of the chromosomes that are in the egg. If there are any chromosomal abnormalities, you'd be able to tell from the polar body.

Of course, not everybody can afford IVF in the first place, but for those that can this might be a way to ensure that a woman my age (36) has a healthy baby. Most of us will probably just have to muddle along with nature and hope for the best... at least for now.

Links:

An abstract from a study about a possible function of polar bodies.

All about meiosis: scroll all the way down to see oogenesis.

Word Of The Day

gemetogenesis: The making of gametes. Gametes are the sex cells, or eggs and sperm. Sometimes you hear this referred to as spermatogenesis or oogenesis, meaning egg or sperm production. They are not produced in exactly the same way, which makes sense if you think about it. Eggs are large and have lots of cytoplasm. For the first divisions after fertilization there is no time for growth, so you end up with lots of cells the same size as the original egg. Sperm are little and have flagella so they can swim and find the egg. They don't contribute much (just the chromosomes they carry) to the size of the fertilized egg.

Slime and Cytoplasm

(Image from this award winning young scientist's web page.)

The first time I saw real live amoeba in my undergraduate biology lab class I was so excited that I went home and told my family... who reacted with blank stares and shrugs, but really... cells that move around by what looks like a magical oozing motion are cool.

How do they do that? It seems that they have the same kinds of (or similar) proteins that our muscle cells have. These protein filaments can contract and make the cytoplasm move. It looks a lot more complicated than that to me, but that has always been the draw of these "wee beasties"... they act in what seem to be very complex ways.

You can see the same kind of thing happen without a microscope if you look at a plasmodial slime mold. Plasmodial slime molds are also protists, like the amoeba, but they fuse together and make what is essentially a really big cell that has a lot of nuclei in it. You can watch these things flow around without a microscope... and I still find it so exciting to watch that I wanted to share it with you.

In this You Tube Video you can see a slime mold start out in one lump and spread out to cover nearby objects... flowing in a complex-looking, fascinating, and slightly disgusting way.

Links:

Actin and Myosin in Nonmuscle Cells (from an online cell biology text)

You and 30 of your closest friends could culture your own slime mold for less than $1.00 each.

An Abstract from a paper about the toxicity of ethanol and some other chemicals on Plasmodial Slime Molds.

Word of The Day

Cytoplasm: The jelly-like contents of a cell.

Measurement

Since science is really only concerned with what is measurable, measurements of various kinds are very important and pop up all over the place in almost any study of anything, but the numbers are only as good as the equipment and the people using the equipment. If you need centimeters and all you have are rulers with inches on them, you're in trouble. Or you could have the fanciest gas chromatograph on the market but only somebody like me to use it. It wouldn't do you any good.

If you've ever needed a really straight line, you have experience with this. The saying goes "Measure twice. Cut once." If you want a straight line you probably need more than two measurements. You start at the edge of your material and go... say ten inches (Why are you using inches instead of centimeters, anyway?). You make four or so marks along the length at ten inches and then try to connect them, but they aren't really all lined up. Some are a little farther out than others and you end up making a "best fit" line, which, if you are really lucky, looks straight.

What you are lacking is precision. Your lines are all pretty close to ten inches so your accuracy isn't bad, but sometimes you marked toward at the far end of the little black measuring tick and sometimes at the close end, also the ruler might have been at a slight angle sometimes, making slight variations in the measurements. Precision is the ability to come up with the same answer over and over again when measuring the same thing over and over, and it has a lot to do with both the equipment and the training of the person using it.

Accuracy is important too. Just because you came up with ten inches on the dot, every time, doesn't mean you have ten inches. Your ruler could be wrong or you could be looking at it and seeing the number ten where it should be twelve because the six-year-old took a pen to your ruler.

Precision sounds wonderful. It's a word that makes me think of professionalism, but precision without accuracy can be disastrous. Just think of the surgeon that could make a cut within a millimeter of where he intended, but took out the wrong organ. A little more accuracy and a little less precision might make the patient a little more alive.

Links:

If you ever need to collect measurements for the EPA... here are the methods.

The National Institute of Standards and Technology's Center for Nanoscale Science and Technology.

Here's how Australia measures things.

Word of The Day:

Bias: There are several ways this word is used in statistics (and we are talking about some very simple statistics here) but in measuring things, your group of measurements would be biased if they were wrong in some way that caused them not to fall into a "normal" bell curve... for instance, if they were precise but inaccurate because of that pen mark on the ruler's number two that made the 12 look like 10.

Making Hydrogen

(the BMW hydrogen 7)

A group of scientists have figured out a seemingly easy way of getting hydrogen from water. They are using special clusters of aluminum atoms that are arranged in a way that allows them to act as catalysts.

Catalysts are very common in biology, so I know something about them. You do too, even if you don't realize it. Think about what happens when you pour hydrogen peroxide on a cut. It bubbles. Right? Why does it bubble?

Hydrogen peroxide has two hydrogen and two oxygen atoms in it (H2O2) and you have a catalyst called catalase in your body that helps free some of the oxygen, turning the peroxide into water and oxygen. A catalyst greatly decreases the energy and time required for a reaction to take place. In this case it's very dramatic. That hydrogen peroxide might turn into water and oxygen on its own... if left alone for a few decades... but add a little catalase and it happens in seconds. In your body catalysts are mostly proteins that "hold" onto the chemicals and apply pressure in just the way that encourages the chemicals to react in a specific way.

In the case of the aluminum (which is not a protein, but you knew that) it needs to be arranged in a cluster of atoms so that one of them has a tendency to accept electrons and another to donate electrons. This lets the water bind to the cluster and frees some hydrogen. Without the aluminum the reaction requires the addition of energy (heat or electricity) but with the aluminum clusters, the reaction can happen at room temperature. Now, if they can just figure out how to unbind the remaining oxygen and the extra hydrogen atom from the aluminum, they will be able to reuse the aluminum clusters over and over again.

Links:

Read all about it here.

Some facts about hydrogen as a fuel, from Stanford.

Phrase of The Day

Lewis Acid: A compound that can accept a pair of electrons. A Lewis Base can donate a pair of electrons. This is a slightly different than the definition of an acid as a chemical that has a pH less than 7.

Winter Fish Kill

(There were plenty of fish in this lake... they just didn't want to be caught.)

The only time I generally fish is on the summer backpacking trip I take with my husband every year. We go to remote places so that we won't have much company, but it's incredibly frustrating to spend two days backpacking up to some remote mountain lake only to find that there aren't any fish. We've had this happen even when oldtimers have assured us that there is indeed a fish population in a particular lake.

The first time this happened on one of our trips my husband just shrugged his shoulders and said, "I guess it was winter killed". I pictured it being so cold up there that the lake froze solid, killing the fish... not too hard to believe when you are up at dawn in July, in the mountains, wearing three layers, a stocking cap and gloves, and still a little too cold for comfort. Even so, it isn't likely that a fairly deep lake would freeze solid. So what kills fish during the winter?

When it gets cold the water on top of the lake freezes. This is handy, Ice floating like that, or it might really be likely to freeze solid. However, the ice on top of the lake restricts the ability of the lake to absorb oxygen. This isn't so bad because the fish's metabolism slows and they don't use as much oxygen as in the summer. As long as light can filter through the ice there will be some oxygen produced by the plants, but if it snows a lot then the snow will block the light. Eventually, if it doesn't melt off soon enough, the dissolved oxygen levels become so low that fish will start to die.

Unfortunately, it seems that trout (our fish of choice) are particularly sensitive to this. The population will eventually bounce back as long as there is a stream or something to connect the lake with other fish populations.

... and we can always spend the time taking lots of pretty pictures.

Links:

EPA's information about mercury in fish.

National Fish and Wildlife Foundation

The Nature Conservancy's program to map freshwater biodiversity.

Word Of The Day:

Biodiversity: The number of different kinds of living things in a given area.

ESO's VLT

(The center of a galaxy as seen by the VLT.)

Spend just a little time wandering around in the world of science and you'll run into a lot of esoteric acronyms that stand for very long and incomprehensible words. That's one reason I was intrigued by the VLT.

ESO is the European Southern Observatory, and VLT stands for Very Large telescope. There's an acronym I can live with.

The VLT is really four separate telescopes with mirrors 8.2 meters (26 feet and almost 11 inches) across. Each of these can be used alone, and generally they are used that way a lot, but when used together in groups (along with four smaller, movable Auxiliary Telescopes) they can greatly increase the resolution of an image. When they are used this way they are called an Interferometer.

Links:

A Really Excellent You Tube Video

An Explanation of Interferometry

Word of The Day

Resolution: The ability to distinguish two separate points as to distinct points rather than one big blur. The ESO website says that the VLT could see a car's headlights as two points if the car were on the moon.

Dementia

Dementia isn't really a disease, it's a set of symptoms that can be caused by lots of different things. Can't remember where you put your keys? Well, if everything else seems to be working okay then you probably don't have dementia. Dementia is when you have two or more problems with the way your brain works and the list of symptoms is quite extensive. A person with dementia might have hallucinations, language problems, motor skill problems, or emotional and personality problems to name just a few.

Alzheimer's disease is the disease that comes into my mind when I hear the word dementia but vascular problems and stroke can cause it also, and there are several other diseases and disorders that can cause it. The scary thing about dementia is that it can't usually be cured and it gets worse over time.

What I want to know is, what can I do to prevent it from happening to me. There are some computer games and mind bending puzzles and things on the market for that and I was wondering if they were helpful or not. Here is what I've learned about Dementia prevention.

1. Since stroke and vascular problems cause some kinds of dementia, the kinds of things that prevent those problems are helpful. Quitting smoking, exercising, stress reduction, and eating healthier are good ideas.

2. For the above reasons, it makes sense that statin drugs would be a good idea for those at risk. This study seems to support that idea.

3. Ginkgo doesn't seem to help, according to this study.

4 While no one particular mind game seems to have been studied, it does seem that using your brain regularly reduces your risk for dementia.

Links:

Leisure activities and the risk of Dementia in the elderly.

The National Institute of Neurological Disorders and Stroke

A List of Symptoms

Word of The Day

Aphasia: A loss of language ability. This is usually caused by damage to the brain and can occur in some kinds of dementia. It may only be the loss of some words or it could be an inability to use them properly.

Cryobiology

My dad had a buddy when I was growing up that swore up and down that if you took a live duck and put it in the freezer and froze it solid, you could then thaw it out and it would still be alive. I never tried it, so I can't say for sure if it would work or not, but I doubt it. Some animals can take very cold temperatures but the guy insisted that the duck could be frozen rock solid.

Then there are those companies that say they will freeze you so that some day science can figure out how to thaw you out and cure your ills and then bring you back to life? I wouldn't bother. Science has to figure out a safe way to do the freezing part before it's likely to work. The problem isn't in the thawing out, it's in the freezing.

When you take a few cells and start to freeze them, two different problems come up. First, if you are freezing them slowly, ice crystals form outside the cells. Ice is frozen water (I hope you knew that already) and so when it becomes ice there is now less water outside the cells. Water, in liquid form, tends to move from where there is more of it to where there is less of it. That's the process of osmosis and since there is suddenly less water outside the cells than there was, now the water moves out of the cells and dehydrates them, damaging them.

The second problem is caused when you freeze them quickly, like dunking them suddenly into a bath of liquid nitrogen. There is plenty of water inside the cells and it becomes ice crystals. Ice expands when it freezes (An oddity of water. Not all liquids are like that.) and the crystals cause severe damage to the cells.

So, if you want to freeze some cells you need a few things. You need to figure out the optimum rate of cooling and you probably need some mixture of solutes outside the cells that isn't toxic and can help keep the osmotic balance where you want it. These problems are solvable for thin layers of tissues where the cells are mostly similar or for individual cells of the same kind (like sperm) but large organs with lots of different kinds of tissues and cells in them pose greater problems that haven't yet been solved. You can't bathe all of the cells in the optimum solution (which might be different for different parts of the organ) and you can't freeze each of those tissues at the optimum rate.

True, we might solve the problem some day, but till then you might prefer to spend your money on things you can enjoy while you are alive, or you could donate it to you grandchildren's college fund. On the off chance that you don't have any grandchildren, I have paypal.

Links:

A simple and easy to understand description with diagrams.

The Society for Cryobiology

The abstract of a scientific paper about a method for figuring out if frozen bacteria are still viable.

Word (or phrase) of The Day

Osmotic Balance: This is defined differently for different situations but basically it always means that the water is staying where you (or the living system) want(s) it. In freshwater fish there is a higher water concentration outside the fish than in it. The fish has to keep too much water from invading its tissues and so pumps it out to maintain it's osmotic balance. In saltwater fish the situation might be the other way around. Remember, osmosis is all about water.

Hiatus

Sorry about the unexpected hiatus. Regular posts will resume this coming Tuesday with a post about cryobiology.

Salmonella

(Image from this UW Madisonpage)

This last summer we had a local outbreak of salmonellosis, which is what they call the illness caused by salmonella. Local officials traced it to our water supply but not before a lot of people got sick. My family didn't ever get sick, and nobody died, but the whole town was without water for a while.

Salmonella is a rod shapped bacteria that lives in the intestines of birds and animals and sometimes ends up in food (or water, in our case). Everybody is at risk from salmonellosis, but older people, very young people, or people who have weak immune systems, are at increased risk.

People who get the disease get a fever and diareah, and they might have headaches and nasea. It can be life threatening to those who are at increased risk for the diesease.

It gets into our food from undercooked meat and poultry, and occasionally from eggs. At one time only eggs that were contaminated with feces seemed to transmit the diease but now perfectly fine looking eggs can get salmonella in them before they develop a shell and leave the chicken. All eggs that you eat should be cooked or pasturized first. You can't pasturize eggs at home, at least I haven't seen anything anywhere to indicate this is possible or safe, but you can buy pasturized eggs in the carton in some parts of the country. Otherwise, you should "coddle" your eggs before making hollandaise sauce with them. I have a link to dirrections for this below.

Links:

Egg coddling... the microwave method at the bottom of the page looks easy.

USDA fact sheet about salmonella.

A stuffed giant sallmonella bacterium. Just what you always wanted.

Word of The Day

Bacilli: The plural form of bacillus, which means rod-shaped. Salmonella are bacilli.

Statistics

Let me tell you a story about my graduate thesis. It was entitled The Partitioning of Benzo(a)Pyrene in the Pregnant Laboratory Mouse. What I was working on was how this chemical and it's metabolites move through the placenta and so I took tissue samples from the mother, fetus, and placenta of lots of mice and then compared the concentration of this chemical in all of the tissues. It was not terribly important research and was not published anywhere.

When I was writing up my results I went back to my Biostatistical Research Analysis class notes and figured out which mathematical test I needed to use to find out if there was a significant difference between the groups of samples. I found that there was and took the results to my mentor, who looked at them and told me I had it backwards.

A few weeks later I presented my research to the department and the statistician stood up afterward to tell me I had it backward... which I now did, because my mentor had me switch things around.

My point? If you're going to suspect one piece of any research, suspect the statistics. Lots of times even the big scientific honchos don't know what they are doing and one little mathematical slip someplace can make a huge difference. If the work is important to you, look at the numbers that the statistics are derived from and see if the conclusion makes any sense.

The other piece of knowledge I derived about statistics from that period in my life was this: correlation does not equal causation. For instance, you might notice a strong correlation between school attendance and owning an MP3 player. You could reach the conclusion that people buy MP3 players because they go to school. That wouldn't be right, would it? It's more likely that people of school age are more likely to be interested in both music and technology... Next time you hear about a correlation between eating cheeseburgers and howling at the moon, you can take it with a grain of salt.

Links:

FedStats: Government statistics. You can probably trust them. Really.

A statistics textbook online.

A little shorter and easier explanation.

Word Of The Day

Margin of Error: Since the president elect used this phrase in his weekly address, I though it would be a good one to define. This represents how precise a number is. If the margin of error is small, that means the scientist is pretty sure she has it close. If it is large, there is a lot more "wiggle" in the number. This number is often used with the words, "plus or minus," in front of it. For instance, "the average grade of the class was 70%, plus or minus 20%." That's a huge margin of error. The actual average could be anywhere from an A to an F. You wouldn't want to have much faith in that number.

Umami

(image from healthline.com)

I will cover cryobiology, a subject that came up in the comments last week, on Tuesday, but today I want to talk about something I came across a few weeks ago while listening to The Splendid Table on NPR (a cooking show).

The host talked about some mysterious taste called umami that I didn't remember ever having heard of before. Remember high school biology? The teacher had a giant tongue up on the overhead projector and pointed to various places on it. "This is where we taste sweet. Sour is hear, bitter is here, and salty is here. These are all the tastes."

Was I the only one thinking, "yeah right!"? I was properly indoctrinated though and I have found myself in front of groups of students with my handy dandy giant tongue, saying the same things. But, aha! There is another one. Those brilliant high school students knew it all along. (You suppose there might be other tastes hiding out on there that they haven't discovered?)

Umami means yummy(I don't speak Japanese and the experts said delicious but it sounds like yummy to me) in Japanese because the man who tracked this taste down to a chemical called glutamate was Japanese. If glutamate is sounding familiar to you, think MSG. Some people have a hard time with MSG and this taste seems to be triggered by all kinds of meats and cheeses, so what the food world really needs is a replacement for MSG that's more like the chemicals in meat that cause the taste.

That leads us to the receptor for the umami taste, which looks like (or would if you could see it) a very tiny venus fly trap. I only know that because the scientists named it the Venus Fly Trap Domain (there seems to be a venus fly trap domain involved with other kinds of receptors too). It seems to take two chemicals to cause this trap to snap shut. So far as I have been able to tell, nobody has put this taste on the map of the tongue yet and so I am unable to add it to my giant tongue transparency...

several reasonably reliable sources (including this one) tell me the map of the tongue is a myth anyway and you can taste most flavors all over the tongue. This seems strange to me since the professors in grad school had me teach a lab about this (and later I taught the same lab myself) to hundreds of students and it all seemed to work out fine... maybe college kids report what they think they are supposed to? I'm not going to repeat the experiment right now, but maybe I will later.

Links:

This paper is talking about Venus Fly Trap domains and allosteric control of agonistic affinity.

This Wired article is a lot easier to understand.

This article from Chemistry World shows us how chemicals work together to make the umami taste stronger.

Word of The Day

Agonist: A chemical that binds to a receptor and causes it to act in some way.

Jellyfish Revisited

(Picture from this South Carolina Department of Natural Resources page.)

Janna (of The Jannaverse) asked these questions in the comments section of the jellyfish post last week and I'm going to try and answer them.

(I found lots of these answers at the above link.)

So each bud becomes a separate jellyfish?
No. It turns out that some buds can make more polyps and polyps can either live alone or in a colony that looks like big stem with lots of weird flower things on it. The buds for medusa look different that the buds for new, asexually produced, polyps.

How many buds are there on each polyp?
This varies widely.

After all the buds are broken off, does the polyp then die?
No. Some polyps can live for a very, very long time. The jellyfish normally don't live that long-A few months or so.

Do the polyps gather the same kind of food that the mini-medusa will eat later on?
What DO they eat?

Yes. Generally the polyps and the little medusa eat zooplankton. The grown jellyfish eat different things. Some species eat zooplankton their whole lives. Other's move on to bigger things like crustaceans. There are fish and other animals that prey on jellyfish too. Some kinds are eaten by people. Not this person yet, but some people.

Links:

The Zoo Aquarium in Berlin talks about what it takes to breed jellyfish here.

Video of feeding polyps. It's a little blurry.

Word of The Day

Zooplankton: microscopic animals that eat phytoplankton which are microscopic plants.

Astronomy

(this is an illustration of the Milky Way from astronomypictures.net)

First, I want to thank Bob from Black holes and Astrostuff for alerting me to the fact that 2009 is the International Year of Astronomy. Check out the link to find out all about astronomical stuff going on all over the world this year. Also, visit Bob. He has some Hannah Montana 3-D glasses to give away if you happen to live in Ontario and stop by for his Year of Astronomy event.

Now, I heard the alarming news today that our galaxy might have only two arms. That got me thinking about how I know what the galaxy looks like and that led me to discover (Please forgive me here. I'm just a sign maker with a biology degree.) that all those pictures of the galaxy that I've seen are paintings. I mean, how are they going to take a photograph from outside the galaxy? They aren't. So how did the artists know what to paint? Astronomers told them.

Not only might the galaxy have only two arms, it's probably also a lot bigger and moving a lot faster than we thought. Here's the press release about the talk that astronomer Mark Reid gave at the meeting of the American Astronomical Society.

Links:

The Harvard-Smithsonian Center for Astrophysics

All About Mark Reid

The abstract for an article about cosmic masers

Word Of The Day
(in this case, phrase)

Cosmic Maser: I had a hard time with this one. I started with the word Maser, which turns out to stand for Microwave Amplification by Stimulated Emission of Radiation. What that means is that it's a microwave version of a laser, which, as far as I can tell, means that when you shoot microwaves at some molecules (gas molecules in this case) you make more microwaves. Cosmic, means that it happens out in the cosmos. The findings of the study I mention above were made using a radio telescope.

A Big Fat Problem

(image from myrecipies.com)

When it comes to cooking, we have a lot of fats to choose from and we all know that olive oil is the healthiest one that's easily available. However, I don't know about your family but mine isn't going to put up with whole grain pita bread dipped in olive oil for very long. What they want are flaky, tender, homemade biscuits and that's what I'm going to give them... at least sometimes.

The problem? What fat should I use to make these as healthy as possible? I learned to make them with shortening. I can make them with margarine or butter, or even lard. I cannot make a good biscuit with olive oil.

For those of you who don't cook, here's how you make biscuits. First you mix some white flour, baking powder, and a little salt together. Then you cut in some fat (you mush it into the flour with a fork or pastry blender forming little flakes of fat and flour). Then you mix in a little cold milk, roll them out and cut them into round shapes and bake them till golden. This isn't health food but I'm not trying to kill my family either. The flakiness is caused by the fat flakes melting in the oven as the biscuits bake, so you can't use oil.

And so, I set out on a mission, an internet odyssey, to find out which fat would be better for my family: butter, margarine, shortening, or lard.

A fat that is saturated has lots of hydrogen atoms bonded to it and tends to be solid at room temperature. These are usually animal fats. We threw out the polyunsaturated and monounsaturated fat when we threw out the oils. They are better for you but they are liquid at room temperature and won't suit our purpose. Trans fats started out as unsaturated fats but had hydrogen atoms added to them to make them more solid at room temperature.

So we have saturated fats: butter and lard, or trans fats: margarine and shortening... So which is worse?

This doctor says Trans fats are worse because they lower your HDL (good stuff) and increase your LDL (bad stuff). He says that saturated fats only increase your LDL.

However, the same guy, when asked which is better, butter or margarine said to pick margarine.

Okay, I don't have any margarine in the house but I do have some shortening. It occured to me to check the ingredients: selected meat fats (lard, tallow, and hydrogenated lard), partially hydrogenated soybean oil with mono-and diglycerides added; BHA, propyl gallate and citric acid added to protect flavor.

Ooops! Lard didn't have enough hydrogen on it already? Here we have a product that is made up of both trans and saturated fats. Shortening is off the list! This is a little heartbreaking because it's so easy to use.

This is the internet. One source is not enough. Let's consult somebody else: butter or margarine?

This newspaper article doesn't really answer the question, but points out that butter has cholesterol in it and more fat than margarine.

The American Heart Association says Margarine: but I get the feeling they don't approve of flaky biscuits.

So I think the answer is that I shouldn't serve biscuits every night of the week and when I do, I should make them with margarine. If I use tub margarine they won't be quite as flaky as biscuits made with shortening but they'll be healthier. If I want top notch biscuits that won't raise Hubby's cholesterol quite so much, I ought to opt for a shortening made from vegetable oils rather than the kind I have on hand. I think...

Links:

The National Association of Margarine Manufacturers wouldn't be biased, would they?

Snopes weighs in.

The American Butter Institute just says, "things are better with butter".

Food groups, oils and butter, and cancer of the oral cavity and pharynx (From the British Journal of Cancer)

Word of The Day

Trans-isomer: this is when you have a couple of carbon atoms that are double-bonded to each other and the hydrocarbons that are bonded to those carbons are arranged on opposite sides. Because of the shape of the bonds, trans-isomers have a straighter or flatter shape than cis-isomers that have those hydrocarbons on the same side. This is a case where the stereochemistry of molecules can make a big difference in the way they behave, even if they have all the same kinds of elements in them.

Microwave Ovens

My dad remembers his first television. You might remember your first personal computer (Mine was a Comodore 64. It was cool.). But the thing that made me sure that all those science fiction books were coming true was our first microwave oven. No waiting hours for baked potatoes! For a while I tried to cook everything in the microwave. Dad bought me a cookbook and we had dinner ready in fifteen minutes flat almost every night for a while... um, I don't do that anymore.

But how did it work? Nobody could tell me. Not really. Why did some things cook faster? Why did frozen burritos have really hot spots and still frozen spots after their allotted two minutes? The answer lies in both the wave and the water: that is the microwave and water molecules.

First, lets look at a water molecule.

Okay, it's not really a water molecule. It's a drawing I made of a water molecule. H2O means that it has two hydrogen and one oxygen atom and they are sharing electrons. But they don't share them evenly. The oxygen atom hangs onto them more and this causes it to have a slight negative charge and the hydrogens to have a slight positive charge.

That charge is important in how the microwave affects it. The microwaves in a microwave oven oscillate back and forth with an electric and magnetic field that is at just the right wavelength to cause those water molecules to spin. Since heat is the energy of molecular movement and this spinning causes a great deal of movement, the water heats up fast.

The hot water in the food heats the rest of the food, so food with less water in it takes longer to get hot. What about the hot spots in the frozen food? Ice doesn't act like water. Those microwaves have a hard time affecting frozen water so the microwaves grab onto the spots that have started to thaw out already and those are the places that get hot first.

Links

Here is a great page with answers to all kinds of questions about microwave ovens.

A You Tube video of a bar of soap in the microwave

The abstract of a journal article talking about how microwaves can be used to treat injuries.

Word of The Day

Oscillate: To move back and forth around a midpoint.

The Common Cold

(image from epidemic.org)

You probably already knew that that common cold is caused by a virus. Viruses aren't like bacteria in that they can't be killed by antibiotics. You knew that. What you might not know is that the alcohol in had sanitizers doesn't kill viruses either. Physical contact is a common method of contracting a cold and hand washing seems to be the best protective measure.

This week's Science Friday on NPR covered, among other topics, colds and flu viruses. Here are a couple of other tidbits of information I picked up about the cold virus.

One reason we get more colds in the winter is that the virus survives better at colder tempuratures.

One reason there isn't a "cure" for the common cold is that even if you manage to kill the viruses in your body, you won't get rid of the symptoms. The symptoms of a cold seem to stem from your body's inflamatory response to the virus and once that's underway you just have to ride out the process. You're stuck feeling rotten or taking medication for the symptoms for about two weeks.

Links

These folks found that when a child has a cold, T-cells seem to move from the blood to the airways.

Now you can own your own giant stuffed Rhinovirus

Word Of The Day

Capsomere: the proteins that make up the capsid which is the outside covering of a virus. This is what your immune system uses to recognize and respond to the virus and the capsid also lets us make vaccines to help your body respond to viruses it hasn't encountered. There are just too many different kinds of cold virus to make a good vaccine for it.

Primary Literature

(This is the cover of the current issue of Science magazine)

When you are in grade school you might get away with writing a research paper entirely from information you found in an encyclopedia. As you move on to high school and some college classes, you have to use magazine articles and books for you research paper. However, if you go into the sciences, there will come a day when the professor says to you, "I want you to use the Primary Literature for this paper".

When I put together a post for this blog, I try to find at least one article from a scientific journal somewhere on the web that I can link to about that subject. These are hard to read. They have names like, Type I IL-4Rs Selectively Activate IRS-2 to Induce Target Gene Expression in Macrophages, where you typically can only fully understand a few of the words in the title.

The problem, for lots of people, is that scientist speak a foreign language. Still, it's worthwhile to decipher these things if you want to be on the cutting edge of science. Primary means first and reading a scientific article is getting the information first hand from the person or people who did the study. If you really understand it and have all the equipment and time, you ought to be able to go out and repeat the experiment after reading about it. Then you would know for sure if it all worked the way the author said it did.

There is a shortcut. You can just read the abstract which is always at the top and is a sort of synopsis of the paper. The abstract should tell you in a general kind of way what the experiment was about and what it indicated. If that's as far as you get, you're still way ahead of the general population that gets its science news from television and newspapers.

It's important to keep in mind that just because a study was published, doesn't mean it was a good study. On future Sundays I plan to go into what makes up "Good" science, but for now it's safest to remember that a single paper may or may not mean anything but if ten papers (from ten different studies) came to the same conclusion, it's probably significant.


Links

When Peer Review Produces Unsound Science

This man thinks scientist should learn to talk to regular people.

This is a very long and interesting page about science and the internet.

Word of the Day

Empirical: Observable. Scientists don't study things that you can't measure in some way. For instance, you won't find a scientific study about what the prettiest color is but you might find one that told you what color most people preferred. You can measure people's preferences. You can't measure something like how pretty a color is.

Organs on Ice

Organs generally have to be shipped someplace after the donor no longer needs them and they are kept very cold because cold temperatures slow down the natural process of decay, but ice in the tissues is bad. Living cells are severely disrupted by ice crystals, which is why we can't really freeze people, then thaw them out later and expect them to survive.

So, if you want to keep them cold but not frozen, you want some kind of antifreeze that won't kill or harm the tissues. It turns out that sugars dissolved in water can do that, but the antifreeze capability of a sugar depends on a lot of factors. It depends on the number of water molecules bound to it, the shape and make-up of the sugar, and what kind and how much other sugar is dissolved in the water.

Chemists have come up with a (new and probably better) way to figure all that out. They call it the hydration index and here is a link to an article about it.

Hydration Index: A Better Parameter for Explaining Small Molecule Hydration in Inhibition of Ice Recrystallization

Word of the Day

Steriochemistry: The study of the way atoms are arranged within molecules. It turns out that the arrangement in space of the atoms is very important. The same numbers of atoms of each element can be rearranged in ways that make the molecules act very differently.

Jellyfish Do It Different

(Photo from this National Geographic article)

I love jellyfish. It probably has something to do with living inland and only having seen the ocean two or three times in my life, but it's also because there is something just plain fascinating about them. They just look so darned improbable and they have a fascinating life cycle.

The jellyfish that we commonly see in pictures are at the medusa stage. They are round and filled with water and have long trailing tentacles that can sting prey. These come in male and female and make eggs and sperm respectively. When the eggs are fertilized they become a cilliated larvae that settles to the ocean floor and forms a polyp.

Polyps look kind of like strange, alien flowers with finger-like petals. They are usually very small, less than an inch tall and those "petals" gather food for the polyps. Each polyp can break off little peices of itself that are called buds and the buds make tiny little medusa that grow up to look like the original parents. In this way, each fertilized egg can result in a great many genetically identical adults that can then wash up on beaches and sting people.

Links

Here is an article on National Geographic Kids. It includes what to do if you get stung.

Here is a scientific article that shows how jellyfish blooms and algae blooms can interact.

These guys won the Nobel Prize by making glowing jellyfish protiens usefull to other scientists.

Word Of The Day

Nematocysts: The stinging cells of the jellyfish.

About Science All Week

What is Science All Week?

It's a daily blog about science, written by a former science teacher for anybody interested in better understanding the world of science. It covers a wide variety of topics on a weekly schedule. If you are interested in having your page linked here or if you have a science topic/question you'd like to see addressed here, please write to Marilyn at
marilynzelha(at) yahoo(dot)com.

Schedule

Monday: Microbiology
Tuesday: Physics
Wednesday: Health and Medicine
Thursday: Astronomy
Friday: Environmental Science
Saturday: Chemistry
Sunday: Science Methods and/or History

About The Author

Marilyn has a Master's degree in biology and has taught classes ranging from seventh grade science to college level anatomy and physiology. Chemistry is not her best subject, but she's better at it than she is at ironing.

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