Tarantism

I once had a housemate with a terrible fear of spiders. But she is also very kind-hearted, so instead of killing them, she’d trap them under a cup…and leave them outside of my door. Girl is lucky she’s so cute or she’d find more than a cardboard cutout of David Tennant in her bedclothes. Not that I dislike spiders, no, I was more concerned about tripping over surprise spider prisons. Actually I really like spiders; flies and mosquitoes drive me nuts so anything that eats them is a homie in my book. I even like these guys:

 

Goliath Bird-Eating Tarantula. They are the size of my face, wonder what they eat…Anyway, they’re hairy, scary beasts but there’s really no reason to run even from these guys (besides abject terror). Despite their size and overall creepitude, most tarantulas don’t pose much of a threat to anything larger than their dinner. Most can’t produce symptoms worse than a wasp sting or an intense burning sensation. Painful, yeah, but not lethal (unless you’re allergic).

So now you know! Tarantulas are just big cuddle-bugs!

Except don’t cuddle them, the hairs are strong irritants.

 

Source

Stewart, Amy. 2011. “Wicked Bugs”. Algonquin Books of Chapel Hill. Chapel Hill, NC.

 

PS. Tarantism was a kind of dancing mania in 1400-1600s Italy. Folks blamed it on spider bites but it was probably just moldy bread.

Political (Single-Celled) Animals

Time to talk politics. Not Dems vs. Reps or left vs. right, up vs. down, etc. I’m talking the politics of science, specifically medicine. Although the scene is changing, there have been (and still are) strong inclinations to believe Western scientific/medical practices are the end-all-be-all and everything else is foreign bunk. However, studies and reviews are few and far between actually confirming or denying the actual bunk-itude of non-Western/”traditional” medical practices. But again, this is changing; the World Health Organization now has a list of ailments treatable with acupuncture and other various Eastern therapies are becoming more popular in conjunction with Western ones. This brings me to what I really want to talk about: bacteriophage therapy.

Bacteriophage are viruses that target bacteria, hijacking bacterial genetic machinery in order to replicate themselves. Phage may be lytic or lysogenic. Lytic phage will get to work right quick replicating before making the bacteria literally explode with baby viruses. Cute. Lysogenic phage on the other hand are patient. They hide viral DNA or RNA (viruses may have either) in the bacterial genome until the time is right. Then the bacteria explodes. Furthermore, phage are species specific, so one kind of virus will only attack one kind of bacteria. Beginning to see the possibilities? Human bacterial pathogens don’t stand a chance. And unlike antibiotics, phage will evolve alongside their prey, making them virtually immune to the resistances plaguing modern medicine. So why aren’t we all taking bacteriophage instead of antibiotics? Researched off and on since the latter 1800s, phage were even produced commercially to fight bacterial infections. But challenges were made to the efficacy of phage therapy and antibiotics quickly became much more popular so phage were largely forgotten. In the West, anyway, in Eastern Europe and the Soviet Union, bacteriophage therapy use and research persisted, displaying success in combating multi-drug resistant bacteria with phage. It’s like a miracle cure, but politics prevented phage from staging a comeback in the West. Despite the mounting evidence in support of phage therapy, the reports were all in Georgian, or Polish to a lesser extent (the leading institute in this field since the 1920’s is in Georgia, the one in Poland popped up in the 1950’s). Not terribly popular languages outside Eastern Europe even today. When some papers were eventually produced in English, the writer apparently never spoke to the scientists or even had a basic knowledge of medicine because it claimed (among other things) that the phage were useful against allergies, besides mixing up which phage were to be used on which infections. The Western scientists were not impressed. Even if the English papers were accurate, the most research came from “damn, dirty Commies” so it never really had a chance. UNTIL NOW.

Damn, dirty Commie phage, curing all our shit.

OK, not really “NOW” now, but “now” twenty-some years ago. In the ‘80s phage research experienced a revival in Great Britain at the hands of William Smith. Since then papers have been piling up in support of phage therapy and its superiority over antibiotics. However, more rigorous studies need to be conducted to further understand its efficacy, so it will be a while before you can use a virus on your E. coli infection. Still, when the headlines of multi-drug resistant bacteria loom, remember that for every superbug there’s a superflyswatter.

It just needs to go through clinical trials.

 

Source

Sulakvelidze, Alexander, Zephira Alavidze and J. Glenn Morris, Jr. 2001. “Bacteriophage Therapy”. Antimicrobial Agents Chemotherapy. 45(3): 649-659.

Photo credit Dennehy Lab, Queens College: http://dennehylab.bio.qc.cuny.edu/

Best of Buds 2

I know I promised more taste bud stuff yesterday, but I had spent the last part of work moving some VERY heavy equipment at work and I came home exhausted.

Anyway, this will be short and sweet (sour, salty, bitter and savory). Despite what we all grew up learning about the “taste map” on our tongues, this is terrible and false. While taste buds will respond preferentially to certain flavors, they all respond at least a little to all flavors and there are no sour, salty, etc specific taste buds. Granted, there’s a little bit of mapping with where the taste buds with what preference sit on your tongue, but it varies from person to person.

Now! As to how these tastes actually get tasted, the answer…varies. But only by a little. Different channels and binding sites on the taste receptor cells respond to different molecules and ions to register flavors. Salty and sour flavors are registered when Na+ ions and H+ ions (respectively) come into contact with ion channels on the receptor cells. The resulting depolarization of the receptor cells causes it to signal the appropriate flavor. For sweet flavors, however, the sugar molecule (glucose, sucrose, artificial sugars can also work) attaches to a binding molecule on the receptor cell’s surface to cause cellular depolarization. Savory flavors involve tastants (taste molecules) binding to G-protein coupled receptors. I can talk about those cell surface receptors more later (if anyone even wants to know), but for now know they’re a kind of receptor protein. Anyway, savory flavors register when amino acids bind to the G-protein coupled receptor and cause cell depolarization. Bitter flavors, on the other hand, can be produced by a wide variety of molecules using a wide variety of binding/receptor mechanisms. Anything from alkaloids like caffeine and strychnine or metalloids like arsenic will register as bitter. Notice the inclusion of the poisons? Most animals register toxic substances as bitter, this is a survival strategy; we don’t like bitter things and thus avoid it. So if anyone gives you crap about putting sugar in your coffee, tell them you’re quieting your survival instincts. Also don’t judge, I do what I want!

 

Source

Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.

Photo credit me. Cheesecake credit, Kensie Steakhouse.

Best of Buds

No, it is not my birthday, this is my cake from a birthday long (less than two years) past. Now, I am not a lady usually tempted by fancy cheesecake concoctions. Not really a lady in the first place. But if I saw pina colada or mint choco-brownie or raspberry-mocha-berry-fudgestravaganza cheesecake on a menu I’d typically reply with a scowl and a violent crossing of arms. So it is shocking I even considered hot buttered rum cheesecake. But consider it I did. Besides devouring and digesting it. This was not some weak cheesecake with delusions grandeur of being a dessert drink, this was hot buttered rum reincarnated as a cheesecake for good deeds in its previous life. It was glorious.

My supreme enjoyment was all thanks to gustation. We all should thank our sense of taste; life would be a lot paler without the many tastes of our body fuel. Out would go birthday cake, fanciful cocktails, wine tasting and Cheezits. Spinach with bleu cheese salads, chocolate and mango juice would all be gone with the wind. We would just eat bizarre mashes of what’s good for us and enthusiastically tolerate it all. So then thank GOD AND ALL THAT IS HOLY for taste buds.

You have about 9000 taste buds and despite all the hype about them being color-coordinated taste microphones, they are a bit more complex than that. But just a bit. Taste buds are not the little nubbins all over your tongue, but the taste cells bordering the nubbins are the ones that really work the gustatory magic. The buds are composed of receptor cells and supporting cells. Receptor cells are modified epithelial (inner skin) cells that possess many folds to allow as much taste juice onto them as possible. This “tasting site” is the taste pore. Molecules and ions in the macerated food bind to the pore and results in a chain reaction: the receptor cells provoke an action potential (Remember action potentials?) in connecting nerve fibers and the brain in eventually alerted to the presence of tastiness (or not).

So what triggers this response? Well, it depends. Humans can taste sweet, salty, sour, bitter and meaty things and each have different ways to excite your senses. I will address this is detail tomorrow, but for now I will add that spicy is not a taste. It is your taste buds crying for a ceasefire.

Source

Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.

Photo credit me. Cheesecake credit, Kensie Steakhouse.

Go Toward the Light

Consider this tree.

Consider it well… 

Pretty cool, eh? We’ve all seen weird trees like this, especially those of us that had a bonsai phase. That’s a thing, right? No? I’m the only one? Well, whatever, my mini-larch forest still rocks. Anyway, back to this tree. How do you think this tree got this way? Maybe it was split by lightning, or torn in a storm, or something. But how did it grow with a bend in the branches and not just diagonally outward? This answer is auxins. A shit ton of auxins.

Like humans, plants have hormones. Unlike humans, they don’t give plants acne or cause them to indiscriminately make out with strangers at parties. Auxins in particular are a growth hormone involved with phototropism and geotropism. These are the tendencies of plants to grow toward sunlight and to grow in relation to gravity, respectively. Bonsai demonstrates both concepts very well. If you wrap a wire around a springy, young tree, you can bend the tree at a right angle. Light will then strike one side more than the other, plant cells can detect this difference and the auxin supply to the more illuminated side will taper off. As a result, the dark side of the tree will grow faster, causing the tree to bend until both sides receive equal amounts of light.

Geotropism works in a similar manner. Plant cells are sensitive to the pull of gravity and will grow differently depending on where the gravitational pull is strongest. However! It makes a difference if the plant cells in question are in the root or the shoot. Root cells experience positive geotropism; they grow toward gravity, while shoots experience negative geotropism and thus grow away from gravity. So if you laid a plant horizontally on the dirt, the roots, instead of growing in the direction they were pointing, would grow down into the ground. Meanwhile the shoots would grow up, up and away from the ground. Again, this is a result of different auxin concentrations; they build up in areas experiencing more gravitational pull and peter out in those that experience less.

Though without a central brain, plants have some pretty impressive chemical tricks that allow them to appropriately respond to a variety of situations. Provided those situations do not include acid, burning and a thorough stomping.

 

Source

-. 2010. GRE Subject Test: Biology 5th Ed. Kaplan, New York.

Photo credit, me.

Tree credit, Cape Flattery, WA.

Apologies

Sorry for disappearing so abruptly. I was busy Tuesday and assumed I would get a post out Wednesday before leaving town to see my friends graduate. I had high expectations. Then Reddit happened.

So here’s Old Faithful erupting at sunset to make up for my lack of faithfulness.

Majestic as shit, yo.

 

Photo credit, me.

A Dance of Genes

Hope everyone had a lovely Mother’s Day and showed their mothers and motherly guardians how much they appreciate their hard work. We had scones, worked on a puzzle and watched Guillermo del Toro’s best Mother’s day film, Mama.

Here comes Mama.

Speaking of Mama/mamas, I still owe a post or two on additional exceptions to Mendelian inheritance. These last exceptions include epistasis, mitochondrial inheritance, genomic imprinting and triplet repeat extension.

When one gene is dependent on another for expression, we call that epistasis and the best example is color expression in hair. Because I can, we’ll use Danaerys Targaryen’s magnificent silvery mane as an example.

Maybe she’s born with it, maybe it’s epistasis…Actually, yeah, she’s born with it.

While Dany’s phenotype may be white hair, her genotype for hair color could be a completely different color. She could even be homozygous dominant for black hair, BB. Again, I’m using a simplified version of hair genetics, but Dany’s fireproof and owns dragons, I think I can pretend her hair genetics work like those of mice for the time being. OK, so now she’s genetically black haired. However! She has a separate set of genes that determine whether or not that hair color is expressed; C for color, c for no color. Since Dany does not have black hair, we can safely infer her genotype is BBcc. Without the allele for color expression, Dany’s hypothetical raven waves are in lockdown.

Mitochondrial inheritance is also called maternal inheritance and refers to a set of genes that are always and entirely inherited from the mother. Why? Because I said so. Actually, because the egg is the only gamete (sex cell) to contribute organelles. Sperm have no organelles, just some egg excavation tools and DNA. Eggs, on the other hand, have organelles besides the nucleus and one organelle in particular possesses its own set of DNA: the mitochondria. These are not junk genes, either, mitochondrial DNA includes genes involving cellular respiration and metabolism. Problems with these are rare, but very serious.

The last one did not have any Game of Thrones references but bear with me! It’s Monday and I’m sleepy and y’all don’t pay me, dammit. Geez, I work and I slave…

Source

-. 2010. GRE Subject Test: Biology 5th Ed. Kaplan, New York.

Bad Case of Wrinkle Fingers

Going to take a brief break from genetics to discuss how disgusting my thumb was today. A combination of repeated lid twisting and wearing too small latex gloves this week was giving me blisters in the same spot on my thumb. Worried that too much skin would peel away too fast, I decided to smack a bandaid on that sucker. Theeen I forgot about it until today when I realized the bandaid looked gross and I wanted to put away clean dishes. Because I’m not THAT weird, I don’t have any pictures, so you’ll all have to imagine the skin of my thumb pad pure white, puffy and lacking in much sensation. Oh, also stuff was sloughing off. It was all very pretty and I had a nice freak-out until I got to my computer. Apparently this condition is called maceration and it is an extreme version of the wrinkly fingers you get from sitting in the tub too long. Basically the skin absorbs too much water that can’t/won’t evaporate away. This is a common problem with bandages; waterproof bandages will hold sweat and fluids close to the skin while the ones that aren’t totally waterproof will let in some moisture, which then can’t evaporate away. It’s not serious, but if the macerated tissue isn’t cleaned, bacteria can grow and cause infection. Thankfully, I removed my bandaid before that could happen. Shit still looks weird though.

 

Source

Chandler, Nathan. 2013.  “Skin Maceration Explained”. Discovery Health. May 11, 2013 < http://health.howstuffworks.com/wellness/men/sweating-odor/skin-maceration.htm&gt;

A Song of Genes and More Genes

Contemplated continuing the saga of molecular genetics yesterday, but then I discovered Hyperbole and a Half and sort of broke. Mostly fixed now (but still occasionally and quietly giggling to myself) so I’ll continue in the vein of Reasons Why Mendel is Wrong Even Though We Love Him. Starting with codominance.

Codominance occurs when an individual is heterozygous for a certain trait and the two different alleles are fully expressed. The easiest example is the A, B and O alleles for blood type. They code for different identity proteins in the blood, so you can have blood type AA, AB, BB, BO, AO, BO or OO. Alleles A and B are codominant, so your body equally produces both proteins if your phenotype is AB. Since O is recessive (and not codominant), genotypes AO and BO display A and B blood types, respectively. Genotype OO results in blood type O. Confusing enough? Better not be, I haven’t even gotten to incomplete dominance!

Incomplete dominance is when a heterozygous genotype results in incomplete expression of the dominant allele in the individual’s genotype. Basically, the dominant allele works and gets expressed, but it would need a second dominant allele to actually get the job done. Instead, the dominant allele produces whatever proteins it can while the recessive allele dinks around and makes nothing. Or at least nothing that works. Teamwork, people. A good example is Daenerys Targaryen.

KHALEESI ❤

Let’s look at her phenotype for flammability; Dany is completely fireproof (I call her Dany, it’s OK, we’re homies). Her genotype is homozygous dominant, FF. Although it is uncommon for a dominant allele to be rare, the fireproof allele (F) is very rare. So Dany’s baby gets a dominant allele from her and a recessive allele from Daddy Drogo. This recessive allele codes for a defective protein so that Daddy is highly flammable (considering his people cremate their deceased, this makes funeral preparations easier). But Baby Rhaego is genotypically heterozygous, so he has (or SPOILERS! would have had) Drogo’s defective proteins bumbling around with Dany’s highly effective proteins. So he is only partially fireproof because the one dominant allele cannot produce enough protein by itself to make him fully fireproof.

There are more exceptions to Mendelian genetics, but I’ll let all y’all absorb this stuff for now.

Mendel, there are too many exceptions. Daenerys is tired of your shit.

Source

-. 2010. GRE Subject Test: Biology 5th Ed. Kaplan, New York.

Clash of Genes

Since I named him the other day, I may as well explain Gregor Mendel’s laws of genetics. Gregor Mendel was an Augustinian friar in the mid-nineteenth century who spent WAY too much time with his pea plants. Except maybe not too much time, because by observing their traits and “mating” certain plants, he laid the foundation for modern genetics with his study of genetic inheritance. His laws include the Law of Dominance (which I explained Monday), the Law of Segregation and the Law of Independent Assortment.

The Law of Segregation is not racist, don’t you folks worry, it just describes the separation of alleles during meiosis (remember the Hand Jive?). When developing sperm and eggs divide, the final product only has one copy of one allele for one trait. Using the creepy-ass Lannister Twins as an example, Jaime’s bb (blonde blonde) gene is segregated during meiosis, with one b allele in each new sperm cell. Jaime’s niece/nephew-children do not get two blonde alleles from him, they get one from him and one from Mother/Aunt Cersei. This is especially important to understand in cases of the segregation of a heterozygous genotype, when the alleles are different.

Now, the Law of Independent Assortment sounds suspiciously similar to the Law of Segregation. The laws themselves are very different, but many a biology student has been tripped up remembering the name of each law. The Law of Independent Assortment refers to the manner in which different genes for different traits sort independently of one another during meiosis. Meaning the genes are not linked together and inheritance of one trait does not guarantee the inheritance of the other. So Cersei’s sass-brows will not necessarily be inherited with her hair color.

 

However! Since Mendel, we have discovered there are many linked genes, some autosomally linked (linked gene on a non-sex chromosome) or sex-linked (linked gene on a sex chromosome, usually the X because it holds more). For instance, sass-brows or no, any blonde kiddos of Cersei will also have her blue eyes since the two genes are autosomally linked.

Although that is not all for genetics, that is all for me today. I am tired from avoiding homeless men, cyclists and petitioners. Time for that mini wine.

 

Source

-. 2010. GRE Subject Test: Biology 5th Ed. Kaplan, New York.