Friday, October 31, 2014

The Friday Five – Halloween edition

Highlighting some of the coolest science news we’ve seen lately...Halloween edition!

1. Are ghosts real? Science says there’s not a ghost of a chance!

The scariest thing about this scene:  the paucity of channels on the TV.

2. Looking for a way to merge your love of physics with trick or treating? Check out these physics-themed Halloween costume ideas.

This Halloween, go as anti-matter!
 
3. We have nothing to fear but biochemistry. The American Chemical Society has released a neat little video about the chemistry of fear.


 

4. Ever wonder what would happen if you could cross a panda and an owl? A bird with a baboon? Here is a collection of eerie animal hybrids generated with a little help from Photoshop.

The Pandowl

5. Here’s how to make some creepy Halloween decorations from the comfort of your own haunted house!



Science quote of the week:

“Back off, man! I'm a scientist!” –Peter Venkman, Ghostbusters

Contributed by:  Bill Sullivan
Follow Bill on Twitter: @wjsullivan

Tuesday, October 28, 2014

Frankenfood or Monster Myth?



Mary Shelly was wedded to Percy Shelley, one of the
great poets of the early 19th century. But she was fair
writer on her own. Note the bolts on the monster’s
neck. These were added by make-up artist Jack P.
Pierce. He said they were electrodes, not bolts, even
though Mary Shelly never actually wrote that
the good doctor used electrodes on the body.
Can you think of anything scarier for Halloween than an irresponsible scientist letting his creation loose on the world? Now imagine that his creation is something that violates our human sense of decency and reverence for the dead. Well, that’s the story behind Mary Shelly’s Frankenstein.

The movies and stories about Frankenstein’s monster usually highlight the way in which the monster was created and his ugliness and hatred, but that isn’t what the book is about. It’s a story of responsibility in science and toward others.

The Age of Enlightenment had just ended when Frankenstein was written, and the Romantic period was in full bloom. A switch from science to emotion meant that the facts and discoveries about the world now needed to be examined, not just accepted. Here was where Mary found her message – a person must be responsible for the things he/she creates – be it physical things, knowledge, or opinion.


Electrical impulses make muscles move. Adding salt to
freshly skinned frog legs is a lot like hitting the with a
mild jolt of electricity. This is like Galvani demonstrated
with the corpse of the murderer and the image Mary
Shelly evoked in her novella.
The science of the monster’s reanimation was not the focus, but Mary had good knowledge of the latest science of the day, and this is what informed her making of the monster.

Just before 1800, Luigi Galvani had published on the ability of electricity to excite the muscles of dead animals – the innate electrical force of living tissue came to be known as “galvanism.” In 1803, Galvani applied an electrical charge to the corpse of executed murderer Thomas Forster, and the body jolted and moved – a good visual for Mary.

One indication that a story is a classic is whether its themes are applicable to different eras. Frankenstein may be even more applicable to our times than it was to Mary’s. Current debates boil over the uses and limitations of science.

The issue most often compared to Frankenstein’s monster is genetically modified organisms (GMOs). Have you heard of the term, “Frankenfoods?” This is the name that opponents of GMOs and particularly GM foods use to taint the agricultural biotechnology industry.

The fears are that by tampering with nature and introducing genes into organisms, we are creating monsters that might have unexpected effects on us. It’s a good marketing campaign idea, and it has taken off.

Europe and Russia have banned all GM foods, out of fears that they may contain toxins or mutagens that would harm the consumers. One fear is that DNA from the genetically modified organisms would be transferred to the eater and combine with their own DNA. That is a scary idea.

The problem is, you take up DNA from the food you eat every day, although not whole genes as the fearmongers warn. Digestion breaks down DNA, so we take up mostly nucleotides and short stretches of nucleic acid. No recorded evidence exists of uptake of an entire gene.


Dr. Frankenstein used all natural body parts, no artificial
sweeteners, additives or preservatives, and good old-
fashioned electricity. If he was sold in the market, the
monster could be labeled as organic! No genetic
modification here.
Websites and books talk about the dangers of GM foods, but it hasn’t shown up in the scientific literature. Most of the papers that have announced negative ramifications have later been retracted. I’ll give a typical example.

In 2012, a researcher named Seralini from the U. of Caen announced that an herbicide used with GM foods (glyphosate in Roundup) caused tumors. He didn’t just publish it - he had a press conference with the concurrent release of his book on the subject and videos in three different languages. It turns out that he also had a company that was preparing to market a product as a “protectant” against glyphosate. The study was subsequently retracted, but a modified version with a conclusion that “more study is needed” was re-published in a lesser journal, but without peer-review.

Other studies on the dangers of GM foods have been correlative, meaning that when you see “A”, you often see “B.” But that doesn’t mean that A causes B, or that B causes A. Remember this, correlation does not imply causation. This is also seen when assessing the rise in gluten allergy. Gluten allergy goes up at the same time more GM wheat is being used. GM wheat must cause gluten allergy. Nope. Several recent studies (like here and here) show that GM has no more endogenous allergens than wild type wheat.

The truth - we need more studies. There are real issues to be dealt with, like does introduction of a particular gene cause plant toxins to be increased – this could be bad for us. The idea is the same as in Mary Shelly book – we must be responsible for those things we make. No GMO or GM food should go to market without extensive testing.

The testing to date shows that there are no health risks associated with GM foods. Longitudinal studies from 2014, 2013, and 2012 of live stock feeds showed that animals fed GM crops over five generations showed no ill health effects and their meat was exactly like that of animals fed conventional feed. By the middle of 2013, over 600 studies showing that GM foods carried no health risks had been peer-reviewed and published.


Synthetic biology has arrived. Vanilla is a very expensive
crop to produce. But a gene has been constructed and
vanillin is now produced in yeast. They ferment sugar and
produce vanillin. This is more natural than artificial vanilla,
and contains many of the metabolites that make vanilla
taste like vanilla.
The problem with hidden agendas like Seralina's goes both ways; a 2014 editorial on the safety of GM foods was written by a Monsanto employee, the company that markets GM corn and soybeans. Society must be diligent and demand top-notch, transparent science. This was one of Shelly’s themes, Dr. Frankenstein conducted his work in private, with no comment from society about whether it should be done at all.

The next generation will have more issues to deal with, like synthetic biology (not merely taking a gene from one organism and putting it another, but constructing a gene or genes from scratch and then inserting them). We need a science literate population that can judge and reason for themselves. And that’s why we learn biology.



Contributed by Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules



Lupi R, Denery-Papini S, Rogniaux H, Lafiandra D, Rizzi C, De Carli M, Moneret-Vautrin DA, Masci S, & Larré C (2013). How much does transgenesis affect wheat allergenicity?: Assessment in two GM lines over-expressing endogenous genes. Journal of proteomics, 80, 281-91 PMID: 23403254
 
Herman RA, & Ladics GS (2011). Endogenous allergen upregulation: transgenic vs. traditionally bred crops. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 49 (10), 2667-9 PMID: 21784119

Van Eenennaam AL, & Young AE (2014). Prevalence and impacts of genetically engineered feedstuffs on livestock populations. Journal of animal science, 92 (10), 4255-78 PMID: 25184846

Snell C, Bernheim A, Bergé JB, Kuntz M, Pascal G, Paris A, & Ricroch AE (2012). Assessment of the health impact of GM plant diets in long-term and multigenerational animal feeding trials: a literature review. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 50 (3-4), 1134-48 PMID: 22155268

McCall WV, Andrade C, & Sienaert P (2014). Searching for the mechanism(s) of ECT's therapeutic effect. The journal of ECT, 30 (2), 87-9 PMID: 24755719



Friday, October 24, 2014

The Friday Five

Highlighting some of the coolest science news we’ve seen lately.

1. We recently reported on the usage of stem cells to produce insulin. A new study published in the Lancet shows that injection of stem cells into the eyes of nearly blind patients helped improve vision in several of them.

2. A paralyzed man has been able to walk again after a pioneering therapy that involved transplanting cells from his nasal cavity into his spinal cord.

Scientists did the reverse experiment and made his nose run!

3. We live in a sea of information and “scientific studies”. How can you tell the good ones from the bogus ones? Here are some good rules of thumb, even if you do not have a background in science.


 
4. Sex has been around a long time, but sex that involved one member of the species penetrating another is now thought to have appeared about 385 million years ago in Scotland among armored fish called Microbrachius dicki (of course). You can read about the study here and even watch an imagination of the fish sex below (it doesn't take long...they're Scottish after all!).




5. Did all of that ancient fish sex get you overheated? Cool off now with some crazy (but risky!) experiments you can do with dry ice.
 



BONUS!
In our ongoing coverage of celebrities getting newly found organisms named after them, here is the latest:  a new species of tarantula from South America was named Bumba lennoni to commemorate John Lennon.

Science quote of the week:
“Captain, the most elementary and valuable statement in science, the beginning of wisdom, is, ‘I do not know’.” -- Lt.Cmdr. Data, Star Trek The Next Generation

Contributed by:  Bill Sullivan
Follow Bill on Twitter: @wjsullivan
 
Schwartz, S., Regillo, C., Lam, B., Eliott, D., Rosenfeld, P., Gregori, N., Hubschman, J., Davis, J., Heilwell, G., Spirn, M., Maguire, J., Gay, R., Bateman, J., Ostrick, R., Morris, D., Vincent, M., Anglade, E., Del Priore, L., & Lanza, R. (2014). Human embryonic stem cell-derived retinal pigment epithelium in patients with age-related macular degeneration and Stargardt's macular dystrophy: follow-up of two open-label phase 1/2 studies The Lancet DOI: 10.1016/S0140-6736(14)61376-3

Long, J., Mark-Kurik, E., Johanson, Z., Lee, M., Young, G., Min, Z., Ahlberg, P., Newman, M., Jones, R., Blaauwen, J., Choo, B., & Trinajstic, K. (2014). Copulation in antiarch placoderms and the origin of gnathostome internal fertilization Nature DOI: 10.1038/nature13825

Perez-Miles, F., Bragio Bonaldo, A., & Miglio, L. (2014). Bumba, a replacement name for Maraca Pérez-Miles, 2005 and Bumba lennoni, a new tarantula species from western Amazonia (Araneae, Theraphosidae, Theraphosinae) ZooKeys, 448, 1-8 DOI: 10.3897/zookeys.448.7920

Thursday, October 23, 2014

The Monster Mash – Diseases That May Have Spawned Monster Legends

We’ve all been there. Sick with the flu, we stagger around the house in a feverish state. With our baked minds marinating in a cauldron of cytokines, we can hardly formulate a complete sentence. Droopy-eyed and disheveled, we nearly scare ourselves to death when gazing at the reflection of our barely recognizable self. Terrified out of her diaper, your toddler may even run away from you with a frightful scream. As you’ll learn from the list below, there are several diseases that produce symptoms that mimic characteristics associated with legendary monsters.

Vampires

These blood-sucking creatures of the night are believed to have been inspired by the Romanian Prince Vlad, born in Transylvania in 1431. His father was named Dracul, and Dracula means “son of Dracul”. Dracula was a “defender of the Christian faith” who, ironically, gained notoriety by impaling his victims and dipping his bread in their blood before consuming it.
 
Prince Vlad before dinner (left) and after dinner (right).
 
However, the symptoms of porphyria (yes…it is pronounced poor-FEAR-e-uh!) are likely to have contributed to several aspects of vampire lore. While it sounds like a lost Def Leppard album, porphyria is actually a blood disorder that arises when patients cannot make and regulate heme properly (heme is a critical part of hemoglobin in the blood).

Porphyria can cause excessive nail growth and receding gums, the latter of which may make the canine teeth look more like fangs. Moreover, porphyria can cause skin to bubble and blister just minutes following exposure to sunlight. Look no further than 1985’s cult classic, Fright Night, to witness the awesome power of sunlight destroying a vampire.
 

 
Finally, to make up for the compromised hemoglobin production, the treatment for porphyria involves injecting patients with blood. Despite this parallel with vampirism, people with the disease do not “thirst for blood” or bite others.

Pluto from The Hills Have Eyes

Michael Berryman, best known for his portrayal of Pluto in the 1977 cult classic, The Hills Have Eyes, has an unforgettable appearance. While his role as a deranged desert cannibal haunted the dreams of millions, his character did not require hours in the make-up chair. Rather, his appearance is attributable to a rare genetic condition known as hypohidrotic ectodermal dysplasia. People with this syndrome have fewer sweat glands, sparse body hair, and missing or abnormal teeth. In addition, facial features of these individuals tend to be consistent with those seen in Berryman’s photo below. Other than heat intolerance due to a reduced ability to sweat, people with hypohidrotic ectodermal dysplasia are otherwise healthy.
 
Instantly recognizable on screen, Berryman has appeared in dozens of subsequent roles, including multiple appearances in Star Trek episodes and films.

Werewolves

On the opposite end of the spectrum, people with excessive hair, especially when it appears on the face, have long been attractions at circus sideshows. Perhaps the most famous is Julia Pastrana, also known as “the bearded lady” or “ape woman”, who caught the attention of many onlookers during her travels with “the freak show” in the 1800s. There is a name for this condition, which often resembles the classic appearance of a werewolf:  congenital hypertrichosis lanuginosa, or CHL. Babies born with CHL are usually covered in hair right out of the womb. Today, people afflicted with CHL can elect to have that hair removed with lasers.

“Don’t worry, it’s just a little hypertrichosis flare-up!”

Demonic Possession

Schizophrenia or multiple personality disorders are often cited as likely explanations for people exhibiting unusual behaviors. But an autoimmune disease called “anti-NMDA receptor encephalitis” has been recently described that also produces striking symptoms of demonic possession. A first-hand account of this ailment was written by Susannah Cahalan called, Brain on Fire: My Month of Madness.

 
Incidentally, anti-NMDA receptor encephalitis does not induce the green projectile vomiting made famous in The Exorcist. You have to go to Taco-Bell for that.

Zombies

There are a number of conditions that give people a zombie persona, such as that window of time from waking up till you get some coffee in you. While there is no disease that allows you to persist as an undead, brain-hungry zombie, there is a famous one that can drive animals to bite others:  rabies. Rabies is caused by a virus, and, thanks to Stephen King’s Cujo, most of us are familiar with how rabies can transform a puppy into a hellhound. The virus is plentiful in the salvia of infected animals and is transmitted through a bite or scratch. Many pathogens change the behavior of their host in order to spread. The rabies virus infects the brain in such a way that its host organism becomes overly aggressive, increasing the odds that the virus will be transmitted to a new victim through a bite.

Another type of disorder can lead to an eerie change in behavior with shades of zombification. A rare mental illness called Cotard delusion, or walking corpse syndrome, occurs when the afflicted no longer believe they are alive. First described in 1880 by neurologist Jules Cotard, this “delirium of negation” can run from mild self-loathing to severe depression. In the most extreme cases, the afflicted will deny the existence of certain body parts or their entire body. Consequently, they will stop taking care of themselves, even to the point of starving to death.

 
Marilyn Manson or ‘Cotard delusion’ support group?
 
For some interesting examples of zombification in wildlife, be sure to read Mark’s recent post, “Zombies And The Loss Of Free Will”.


Contributed by:  Bill Sullivan
Follow Bill on Twitter: @wjsullivan

 
Schulenburg-Brand D, Katugampola R, Anstey AV, & Badminton MN (2014). The cutaneous porphyrias. Dermatologic clinics, 32 (3) PMID: 24891059

Deshmukh S, & Prashanth S (2012). Ectodermal dysplasia: a genetic review. International journal of clinical pediatric dentistry, 5 (3), 197-202 PMID: 25206167

Kaur S, Juneja M, Mishra D, & Jain S (2014). Anti-N-methyl-D-aspartate receptor encephalitis: A case report and review of the literature. Journal of pediatric neurosciences, 9 (2), 145-7 PMID: 25250071

Ramirez-Bermudez J, Aguilar-Venegas LC, Crail-Melendez D, Espinola-Nadurille M, Nente F, & Mendez MF (2010). Cotard syndrome in neurological and psychiatric patients. The Journal of neuropsychiatry and clinical neurosciences, 22 (4), 409-16 PMID: 21037126

Tuesday, October 21, 2014

Not Quite Dead Yet

Miracle Max had his own methods for determining if
someone was all dead or just mostly dead. They involved
a bellows and Carol Kane’s voice.  But the point is made,
for centuries, people were just guessing if others were
really dead. There were few experts, and they were
probably just comedians in make-up.
Halloween has morphed into a holiday where people see how much it takes to scare themselves. Horror movies, haunted houses, dangerous pranks; people like to be scared.

What scares you the most– spiders, public speaking, death? These three are high on every list of common fears, but it wasn’t so long ago that another fear was in first place – taphophobia. Never heard of it? I bet that its mere definition will be enough to send a chill up your spine.

Technically, taphophobia means “fear of graves” (taphos = tomb, and phobia = fear of), but its common use is “fear of being buried alive.” Premature burial is not an urban legend, incidents have been documented in nearly every society – and not all of them were just in the movies or books.

In the 1800’s and earlier, being dead was a lot like being a duck….. you know, if it looks like a duck, walks like a duck, and quacks like a duck….. The appearance of death was often enough to make a diagnosis and start going through their pockets.

As a good example of the wisdom of the age, George Washington had these last words, "Have me decently buried, but do not let my body be put into a vault in less than three days after I am dead…….., tis well." He wanted a sufficient amount of time to pass to ensure that he was in fact dead.

The Irish wake probably originated in the leaving of the
tomb unsealed for several days, just in case the dead
person might wake. Later, stories came about concerning
the lead in pewter tankards from which the Irish would
drink. Lead poisoning could induce a state that resembled
death. Sometimes, a wake is just another reason to raise
a glass of ale.
Many cultures built time delays into their death rites to make sure someone was truly dead. Greeks washed the dead….. and some would wake up. In more difficult cases, they would cut off fingers or dunk the bodies in warm baths. The custom of the Irish wake began with the Celts watching the body for signs of life. But mistakes were made, often in times of epidemic..... or because they were drunk.

The hopes of preventing the spread of infection often lead to burying the dead before they were quite dead. I give you plague victim Eric Idle in Monty Python’s Search for the Holy Grail – “But I’m not dead yet…. I’m feeling much better.”

In an effort to see how bad the situation was, the English reformer, William Tebb, in 1905 made a study of accidental premature burial. Tebb was quite the joiner; the weirder the society, the more he wanted to join or lead it. He worked with the Vegetarian Society, the anti-vivisection movement, the national Canine Defense League, and formed National Anti-Vaccination League in 1896.

William Tebb’s book on premature burial was a best seller.
You’d think he had a product to sell given the way he
described some of the incidents. In one, Madame Blunden
was buried in a crypt under a boys school. The next day, the
students heard noises from below. They opened the tomb
and coffin just in time to see her die from lack of oxygen.
In his book, Premature burial, and how it may be prevented, with special reference to trance catalepsy, and other forms of suspended animation, Tebb professed that he had found 219 cases of near premature burial and 149 live burials. He had some stunning stories of scratches on the lids of coffins and noises from newly filled graves.

In her 1996 book, The Corpse: A History, Christine Quigley documents many instances of premature burial and near-premature burial (I LOVE the title). Skeletons were outside their coffins, sitting up in the corner of their vault after being opened years later. Others were found turned over in their caskets, with tufts of their own hair in their hands.

How might this happen? What conditions might make it look so much like you were dead that even your loved ones would let them plant you in the ground? The list is long and varied, but here are some of the more common things that can make you look dead:

Asphyxiation – anything that cuts off your supply of air can make you look dead once you fall unconscious – continuation of this condition leads to actual death. You look dead enough and won’t respond to external stimuli, so people assume you are dead. Close the coffin lid, and soon you really will be dead of asphyxia.

Catalepsy – Many things can bring on this catatonic state in which the muscles are rigid (like rigor mortis after death) and no pain is enough make you respond, one example is epilepsy. Hypnotists call their trances catalepsy (Greek for to grab and take down), but true catalepsy is much more severe and can last hours to days. Severe emotional trauma can also bring it on, so you can certainly be scared enough to look like you are dead.

Catalepsy is denoted by muscle rigidity, so it can look like
rigor mortis. But there is also waxy flexibility in some cases.
The dead-looking not dead people can be posed, and they
will hold the pose indefinitely. What little girl wouldn’t love
a cataleptic doll for Christmas!
Coma – In medicine, a coma is unconsciousness that lasts more than six hours and from which a person cannot be roused and will not respond to stimuli. Injury or inflammation of the cerebral cortex and/ or the reticular activating system in the brain stem can lead to coma. The things that can injure these structures are myriad, from traumatic injury, to drug overdose, to stroke or hyperthermia, etc.

To show how medicine has changed, there is now a battery of assessments called the Glasgow coma scale (GCS) that are carried out on coma victims to assess their state and prognosis. In centuries past, you might look at them, hold a mirror under their nose, maybe lift and drop an arm….. bury them.

The GCS has traditionally been used in the hospital environment, but new evidence shows that a prehospital GCS (assessment at scene or in route) can be just as accurate and may benefit treatment choice in pediatric traumatic brain injury patients. The study compared prehospital and emergency department GCS scores and showed that they were similar. They also compared outcomes with prehospital scores and showed a positive correlation. If assessment and treatment can be begun earlier, outcomes should improve.

Apoplexy – this not a very accurate term any longer, and has meant different things at different times. It can refer to bleeding within an organ or bleeding during a stroke. A stroke is very likely to leave survivors that look like they are dead, and are unresponsive. Nevertheless, there are stroke victims who regain consciousness.

Due to the above conditions, many people in the 1700’s and 1800’s made a hunk of change by promoting safety coffins and vaults. These might be as simple as attaching a rope to the hand of the deceased, and running this rope to the surface where it was attached to a bell.

In other coffins the alterations were more elaborate. There might be glass plates to view the face of the dead or a periscope to keep an eye on the corpse. Some thirty designs were patented just in Germany in the second half of the 19th century, including some that contained vibration sensors, and later… a telephone line.

Waiting mortuaries were built in the 1800’s, mostly in
Germany. Since the best sign of death was the beginning
of the rotting process, these mortuaries were basically
holding cells for bodies while nature took its course. If they
didn’t start to smell, they had to look for fangs or a way to
arouse them.
To be successful, those folks above ground must have been very alert. A coffin has only about 20-40 minutes of air, so a person could go from dead to live to dead without the change being noted. To counteract this small window of time, Germany also built waiting mortuaries, where dead bodies could be held for longer periods of time. It came to be accepted that the only reliable sign death was putrefaction --- waiting mortuaries did not smell like flowers or fresh baked bread.

Modern EEG and EKG have reduced the chance of premature burial or cremation, but mistakes do get made. In 2007, a Venezuelan man awoke during his own autopsy, and Quigley also writes of several modern instances of near-premature burial. Furthermore, the need for quick burial during epidemics has been replaced by the need for timely organ harvests – maybe they aren’t done with that kidney yet!



Contributed by Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules



Christopher Dibble (2010). The Dead Ringer: Medicine, Poe, and the fear of premature burial. Historia Medicinae

Nesiama JA, Pirallo RG, Lerner EB, Hennes H. (2012). Does a prehospital glasgow coma scale score predict pediatric outcomes? Pediatr Emerg Care. DOI: 10.1097/PEC.0b013e31826cac31


Friday, October 17, 2014

The Friday Five

Highlighting some of the coolest science news we’ve seen lately.

1. People living with type I diabetes may have something to celebrate as scientists have successfully used human embryonic stem cells to generate beta cells. These insulin-producing cells could one day be transplanted into humans.


2. How do you ward off the obnoxious guy who won’t leave you alone in a bar? Female squid of the species Doryteuthis opalescens can steer males away by turning on fake testes. Interestingly, when the females turn on the testes, they also get a pay raise at work.

Since human females can’t turn on testes like a squid, a fake moustache might be sufficient to keep unwanted men away.
3. Blinded by the light? Neuroscientists have successfully erased specific memories in mice…using light. But they are not using this knowledge for evil, they used it to demonstrate how different parts of the brain - the hippocampus and cortex - work together to retrieve memories.

Bono remembers everything about the ‘90s because he adequately shielded his eyes from the light.
4. Still “cleaning” your ears with Q-tip swabs? Learn more about your ear wax and why you should not interfere with it.

5. Check out these amazing photos of flowers that look like other things.

A kiss from a rose...
Science quote of the week:

“Science moves with the spirit of an adventure characterized both by youthful arrogance and by the belief that the truth, once found, would be simple as well as pretty.” – James D. Watson

Contributed by:  Bill Sullivan
Follow Bill on Twitter: @wjsullivan

Tanaka, K., Pevzner, A., Hamidi, A., Nakazawa, Y., Graham, J., & Wiltgen, B. (2014). Cortical Representations Are Reinstated by the Hippocampus during Memory Retrieval Neuron DOI: 10.1016/j.neuron.2014.09.037

DeMartini DG, Ghoshal A, Pandolfi E, Weaver AT, Baum M, & Morse DE (2013). Dynamic biophotonics: female squid exhibit sexually dimorphic tunable leucophores and iridocytes. The Journal of experimental biology, 216 (Pt 19), 3733-41 PMID: 24006348

Pagliuca, F., Millman, J., Gürtler, M., Segel, M., Van Dervort, A., Ryu, J., Peterson, Q., Greiner, D., & Melton, D. (2014). Generation of Functional Human Pancreatic β Cells In Vitro Cell, 159 (2), 428-439 DOI: 10.1016/j.cell.2014.09.040

Thursday, October 16, 2014

Blood. It’s What’s For Dinner.

Halloween will soon be upon us, and our streets will once again be filled with ghosts, zombies, Lady Gagas, and other terrifying creatures of the night. And you can “count” on seeing a few vampires as well, lurking through the shadows in search of blood.

Okay, so maybe not all vampires are scary. If you have trouble sleeping Halloween night, check out this movie and “howl” with laughter.
The practice of feeding on blood, known as hematophagy, is actually a lot more common than you might realize. A wide variety of creatures suck blood, including bats, ticks, leeches, vampire finches, politicians, and so on. Similar to milk, blood is an easily accessable liquid meal containing many proteins and lipids – it does a body good. Many people who are not undead also consume blood, either directly or cooked in foods like sausages, pancakes, and soups. As seen on an episode of the hit reality TV show, Survivor (Africa), the Maasai of Tanzania get their blood straight out of the tap. They cut the neck of cattle just enough to collect blood to make a milk-blood cocktail, and then allow the wound to heal for another drink in the future.  


But not all creatures can easily digest blood. Plasmodium, the single-celled parasite that causes malaria, had to evolve some clever strategies to deal with the toxic byproducts that accumulate during the breakdown of hemoglobin, the oxygen-carrying molecule that comprises approximately 96% of the red blood cells’ dry content by weight in mammals.


(a) The malaria parasite is injected into the host’s bloodstream by another bloodsucker, the mosquito. (b) Sporozoites migrate to the liver and develop into merozoites that invade red blood cells (c). (d) Gametocytes then develop in red blood cells that can be taken up by another mosquito, which will bite a new host to continue the cycle. Life cycle image from: http://www.nature.com/nature/journal/v462/n7271/full/462298a.html   

While in the red blood cell, the parasite replicates like mad. That feverish replication requires a lot of raw materials, like amino acids to build new parasite proteins. Fortunately for the parasite, those red blood cells are rich in hemoglobin, which can be broken down into amino acids the parasite can use. However, as any malarial parasite (or Dr. Dan Goldberg) will tell you, the digestion of hemoglobin is not trivial. As the parasite’s enzymes break it down, the free heme molecules that are released as by-products within the parasite’s food vacuole are highly toxic. If these heme molecules are not disposed of properly, the parasites would die in their own waste.

Bloodsucking humans have an enzyme called heme oxygenase, which can degrade toxic heme; so unlike the malaria parasite, vampires do not need to worry about heme toxicity. But they do have trouble keeping their teeth clean!

So how does Plasmodium solve this problem? If heme were lemons, hemozoin would be the lemonade. The parasite neutralizes the toxic heme subunits by sticking them together into an inert crystal structure called hemozoin. Hemozoin crystals are non-toxic and provide decorative conversation pieces to dress up the parasite’s food vacuole. Probably looks a lot like Shirley MacLaine’s house.

Hemozoin crystals formed within the food vacuole of the malarial parasite.

Incidentally, the process of building hemozoin turns out to be an Achilles’ heel for malaria, as a number of antimalarial drugs work by interfering with hemozoin formation. Unfortunately, the malarial parasite is remarkably adaptive and has evolved multiple ways to become resistant to several drugs in this family.

Contributed by:  Bill Sullivan
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Goldberg, D. (2013). Complex nature of malaria parasite hemoglobin degradation Proceedings of the National Academy of Sciences, 110 (14), 5283-5284 DOI: 10.1073/pnas.1303299110

Gorka AP, de Dios A, & Roepe PD (2013). Quinoline drug-heme interactions and implications for antimalarial cytostatic versus cytocidal activities. Journal of medicinal chemistry, 56 (13), 5231-46 PMID: 23586757