January 2015 fun facts

Woah, I’m way backlogged on blog posts! Don’t worry, I have some cool stuff in the works and I’ll share soon. In the meantime check out some of the science I’ve been starting my classes off with this month.

Aging research: blood to blood – scientists can splice animals together by creating a wound in each animal and sewing them together- their natural wound healing mechanisms join their bodies and their blood (it’s called parabiosis)! If you splice an old animal to a young one the tissue in the old animal gets “rejuvenated” by the young animal’s blood.  Sounds like the premise for a horror movie.

Scientists have discovered a new antibiotic that kills pathogens without detectable resistance.

Scientists have discovered that tumor cells can actually acquire previously lost DNA (in this case mitochondrial) from “normal” cells, and that the newly acquired DNA restores missing function. Think about that. Somatic cells (or cells that were once deemed somatic but now have become tumor cells) can horizontally transfer DNA. Biology textbooks get rewritten every day.

And, of course, I can’t introduce metabolic scaling and not discuss the invariance of heartbeats.

Enjoy!

Mind controlling parasites- how sci-fi are zombies anyway?

 

Halloween weekend is drawing to a close, and as I type this (looking out a coffee shop window) I can still see the zombie makeup on the faces of those passing by. It’s understandable why the whole zombie thing can be pretty terrifying. In the movies the protagonist usually watches their once fully autonomous friends and loved ones fall prey to some microscopic parasite and become a mindless vessel, obeying the will of their neural captors, tasked with ensuring the survival of the parasite and oblivious to their own health. Good thing it’s science fiction! Right? Well, anyone studying parasitology can tell you that in some cases it’s less fiction and more science.

Whenever I teach the lab on species interaction I always spend a good bit of time on mind controlling parasites. First off- they’re just cool. Plus, there’s a lot of captivating videos out there! One of my favorite being:

(p.s. larva emerging from a caterpillar body below, viewer discretion advised!)

Great music and sound effects aside, it’s always interesting and sort of mind-blowing to see the caterpillar actively defend the larva that just busted through its skin. It really gives you a sense of just how possessed an organism can become at the whim of a parasite. Another zombie-state-inducing parasite infects snails:

And another favorite, the inspiration for the zombie-survival game The Last of Us, infects and alters the behavior of entire forests full of insects:

 

Ok, so mind controlling parasites might actually be all around us, but at least they only infect invertebrates. Right?! Well, no.

Rats have a natural (and understandable) aversion to cats. When they smell cat urine they feel fear and head in the other direction. However, rats infected with the protozoan Toxoplasma gondii, which only reproduces in the cat intestine, are actually drawn to cat urine. The parasite hijacks the sexual arousal pathway in the rat brain, and instead of feeling fear the rat feels sexual attraction to the cat odor. So, just like the snails in the video above, the rats search out their natural predators for the benefit of their parasite.

 

Ok, so mind controlling parasites can infect and manipulate the behavior of mammals as well. But, certainly humans, with their giant and complex brains, don’t have to worry about being influenced and controlled by the whims of a tiny microscopic organism. Right?! Well…

I have a habit of bringing up the universe that exists within multicellular organisms. It’s easy to think of this as a one way interaction- a large organism goes about their business and the little organisms tag along for the ride. But the survival and wellbeing of the microbiome is extremely important- so important that hosts even synthesize food for their microbiome during periods of illness to ensure that their microbial friends stay happy.

Is it possible that some of our microbial friends could be manipulating our behavior for their benefit? Some scientists have recently suggested that might be the case- we might be at the whims of a microbial puppet master. More research is needed to test these hypotheses, but I look forward to the day where taking a microbe-filled pill can change my appetite for the better and bolster my microbiome.

Outside of our bacterial microbiome, we also house a vast virome. Research published in PNAS this week has shown that humans can be infected with an algal virus, and this virus was associated with a 10% decrease in performance on visual processing exams. Additionally, mice infected with the virus took about 10% longer to navigate a maze and explored 20% less.

So, maybe we’re not so autonomous after all. Spooky! Happy Halloween!

Will the real Banana Spider please stand up?

I’ve encountered two different species of giant (subjective classification based on my previous New-York-State-only spider exposure) orb weaver spiders while living in Gainesville (and one non-orb weaver!). Both of which have been referred to as a ‘banana spider’. So, who are these spiders anyway, and which one is really the true banana spider?

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Exhibit A- picture taken at the La Chua trail.

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Exhibit B- picture taken in my front yard. (notice the flash reflection in the front eyes!)

It turns out that there are a few spiders referred to as a banana spider. However, only one of those spiders is pictured above, and it’s Exhibit B- the Golden Orb-Weaver (Nephila clavipes). Exhibit A, with its characteristic zigzag web, is commonly referred to as the Yellow Garden Spider (Argiope aurantia).

Apparently the Golden Orb-Weaver was recently moved out of the Orb-Weaver family and placed in the Nephilidae family because their webs weren’t sophisticated enough. Bummer!

Regardless of species name and web sophistication, if there’s one thing I’ve learned while living in Florida, it’s watch where you walk…

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Banana spider waiting to catch a low flying plane

 

Awesome camouflage

Staying in the lab is tough when you live in the sunshine state. I mean, at SUNY Geneseo it was easier- the lab served as a warm refuge against those Western NY winds and clouds. So every once and again I’ll find a break in the Floridian sunshowers and bring my work outside. However, as any biologist can tell you, work is impossible outside because you always get distracted by some cool critter crawling by your laptop. Case in point: last time I tried this I noticed a little pile of moss moving across the table…

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… so of course I flipped it over…

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…and found legs! (Woah, I need to find out what this is.) Further investigation revealed impressive mandibles and a set of sticky spines:

lacewing2

It looked very similar to an antlion, which is the larval form of a certain family of lacewing. Antlions are awesome in their own right, they form little trenches in the sand and eat ants that fall into their trap. I teach an intro bio lab on the spatial distribution of organisms, and I always take the students outside to hunt for antlions (they are typically (spoiler) clumped together in sandy spots under the eaves of buildings). And I always show this video:

Anyway, it turns out that critter I found was also a larval lacewing! Certain species have sticky spines on their back that trap debris and help the larva blend in with their environment. This isn’t a new tactic- scientists have found a 110 million year old larval lacewing trapped in amber that has fern trichomes stuck on its back. How cool is that?! (Another spoiler: very)

And such is the curse of the biologist- go outside to write and in minutes you are a few Wikipedia pages deep classifying insects.

My writing process

Alright y’all (can I say y’all now? I’ve lived in Florida for almost 4 years…), I’ve been tagged in a writing process blog hop thing by master blogger extraordinaire Dr. Amanda Niehaus. Bio below…

Amanda Niehaus (PhD) is a writer and scientist based in Brisbane, Australia. Her work spans the academic, nonfiction and fiction worlds – and she’s doing her best to integrate the 3. Amanda has been published in Peppermint Magazine, on pillows at the 2013 Brisbane Writers’ Festival, and you can find her online at Easy Peasy Organic (http://www.easypeasyorganic.com), Minimal Worries (http://www.minimalworries.com) and Staying Alive (http://www.easypeasyscience.com) as well as on Twitter as @EasyPeasyOrganc.

I met Amanda at the Evolution and Cancer conference in San Fransisco this last summer. Before knowing about her blogging expertise I let the beans spill that I was thinking about starting a blog (I had a lot of fun putting together a video about some research, I enjoy teaching and sharing the things we learn about our world through science, etc etc) and she told me to run with it. So here we are! Thanks Amanda.

Before I get to the meat of the post on writing, let me just say this: I don’t consider myself a writer. Which is silly, because I just wrote that (typed that?), doesn’t that make me a writer? I don’t know. I don’t consider myself a swimmer, but I like going to the beach and jumping in the ocean. It’s good exercise and it’s enjoyable. Just like this blog, and this post. Although, today I spent all day writing up some results from my research and now I’m writing about writing, so maybe it’s time I reevaluate myself. Thanks again, Amanda.

1) What am I working on?

Right now I’m taking a quick break from writing my first first-author paper to write this post. It’s really exciting and nerve-racking, and it’s embarrassing how slow the words come off my fingers. But it’s getting easier every day.

My research is on the evolution that takes place within multicellular organisms as they age. How mutations can accumulate in the little pools of stem cells that are constantly dividing to maintain your body. I think it’s a wonderful story and I can’t wait to share it with others.
2) How does my work differ from others of its genre?

Well, my science work is novel research. As for my blog, I don’t know. I honestly didn’t purposefully read any blogs before starting this one. I still don’t. I should start reading blogs! I don’t even know what my genre is.
3) Why do I write what I do?

I’m the type of person who goes to look something up on Wikipedia and, an hour later, finds 16 tabs open because I clicked every link along the way. I guess I just think a lot of things are cool and I want to learn about them. And I like telling people about these things. I like to tell stories.

This blog is my outlet to tell those stories (if they won’t fit on twitter and I’m not teaching for a while so I can’t bug my students.)

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Where I’m writing from right now. Front porch and a homebrew, Gainesville, FL.

4) How does your writing process work?

So far this blog has been a perfect storm of  daydreaming and procrastination. I’ll typically learn about something, like the Voyager mission, or think about something, like the concept of a species, or want to share something, like pictures of spiders or eclipses, and if the feeling is perfect (just got to a coffee shop, but can’t bring myself to do actual work yet) I’ll start typing.

 

And thus, just like 99% of all the species that have existed on Earth, my writing process blog post lineage comes to an end. I’m glad that Amanda had a fitness greater than 1 on her post, so she has lineages which can still carry on her story. All of the folks I asked to continue my post lineage couldn’t. Do you want to write a blog post about your writing process? Feel free to continue off of this one!

 

The Ultimate Sunset

April 15, 2014 03:49am

April 15, 2014 03:49am

I took the telescope out during April’s lunar eclipse…

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April 15, 2014 02:23am

… and had a really amazing time. At first it was just the mosquitoes, the clouds, a cool drink, and myself, but after a while people started pouring out of their apartments to see the show.

April 15, 2014 01:18am  Staying homed in with the laser finder, waiting for the clouds to leave.

April 15, 2014 01:18am
Staying homed in with the laser finder, waiting for the clouds to leave.

So of course I invited them all over to watch through the telescope. By the end about 10 strangers were standing around watching the bloodmoon and discussing human history, space, science, etc.

April 15, 2014 12:54am

April 15, 2014 12:54am

Imagine what it would be like not knowing anything about the true nature of eclipses and, one seemingly random and unpredicted night, the full moon started disappearing- and then turned blood red. What a sign!

Luckily, we live in a time where humans have walked on the moon, so we do know a bit about it. So, why does the moon turn red?

Well, what color is the sky? (class shouts blue!) If the sky was blue, then how come images of the Earth from space aren’t of a blue ball? Or we don’t normally see a blue moon and blue stars? The sky appears blue because our atmosphere scatters blue wavelengths of light more than other wavelengths of light. When the sun is low in the sky, like during a sunset, the light reaching your eyes has passed through much more atmosphere than when the sun is high in the sky, causing most of the blue light to be scattered out already (for people who are experiencing noon elsewhere). So all that’s left in the light when it reaches your eyes during a sunset are the yellows and reds.

During a lunar eclipse the moon is behind the Earth, with the sun on the other side. The light reaching the moon has passed through the edges of the Earth’s atmosphere, causing a projection of what we see in a sunset to fall on the face of the moon. It’s the ultimate sunset!

 

Open question: Alright, after reading some Wikipedia articles on diffuse sky radiation and the like… I have a question. If our atmosphere scatters blue light, and images of the Earth from space are possible because sunlight is being reflected off of the Earth’s surface and into a camera, how come the Earth doesn’t appear reddish? You know, since the sunlight has passed through the atmosphere twice (down to Earth and back up to space?)

 

p.s. here’s a paper from 1868 “On the blue colour of the sky, and the polarization of light

Spider Sunday!

I was studying outside and got distracted by a few visitors today. First up is Leucuage venusta: the Orchard Orbweaver.

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I took this picture of a different orchard orbweaver earlier in the year:

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Wikipedia seems to be a bit confused about how many species belong to the Araneidae orbweaver family (but what’s in a species, anyway?). Regardless of who belongs to the family, these spiders get their namesake from producing large spiraling webs to entrap their prey. Unlike my next visiter, Anasaitis canosa: the twin-flagged jumping spider.

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Jumping spiders, members of the family Salticidae, don’t sit and wait for their prey but actively hunt. They use their silk as a tether before pouncing on their meal- allowing them to return to the previous position if they miss.

Spiders are so cool.

 

What’s in a species?

Take two biologists, sit them down, give them a few beers each, and then ask them to define the word “species”. Chances are you’re in for a colorful discussion. “Species” is one of those concepts that made perfect sense in high school, got fuzzy in college, and is something biology graduate students like to debate on the weekends.

Person A: It’s easy, right? If two organisms can create viable offspring, they are part of the same species.

Person B: Well, what about hybrids? You know, like when a horse and a donkey (clearly different species) mate and produce viable mules.

Person A: Well, mules are (usually) sterile, so that doesn’t count.

Person B: Ok, how about the viable and fertile offspring produced when Canids mate, like dogs and wolves or coyotes and wolves?

Person A: But those are recently diverged groups, I’d argue that they were actually subspecies of the same species (since they can produce viable fertile offspring, they’d be a subspecies by definition).

Person B: Alright Linnaeus, now you’re rewriting taxonomy. So you’re saying that as long as two organisms can produce fertile offspring, they’re members of the same species?

Person A: Right, but we can still define them into separate sub-species.

Person B: What about when organisms from two different genera produce viable offspring, like Fatshedera lizei ? 

Person A: Are the offspring fertile?

Person B: Well their are some reports that…

Person A: That’s a plant anyway, the rules are different for plants.

Person B: Wait, what are the rules for “species” in asexual organisms, especially when genetic code can be passed on by horizontal gene transfer? And what about cancer as a speciation event? You know, the idea that a tumor has a separate genome from its host so it should be thought of as a different species.

Person A: No way, man. Cancers are formed from and completely dependent on their host. It’s just an extension of a single organism.

Person B: Not necessarily! The Tasmanian Devil facial tumors are spread between hosts by contact. Why shouldn’t we consider those cells a unique pathogen, no different than a virus spread between hosts? And how should we classify that ‘organism’?

Person A: Are viruses even considered alive?

Person A+B: …I think I need another drink.

Yes, I’ve had similar conversations over the years as a biology graduate student. I was reminded of the species debate after reading about the “out of Africa” concept and human speciation, and whether or not we interbred with members of other hominid groups (and, what that means for the definition of our species).

Sleep with one eye open…

Who knew that the song Enter Sandman was actually about an interesting biological phenomenon? Turns out many aquatic and terrestrial mammals and birds actually sleep with one eye open! The corresponding hemisphere of the brain maintains wakefulness, while the other sleeps.

For instance, Mallards (pictured above) exhibit unihemispheric sleep as a way to keep an eye out for predators. Some aquatic mammals, such as cetaceans and manatees, keep one half of their brain awake to control surfacing for air while the other half sleeps.

The phenomenon of unihemispheric sleep has called into question the definition of sleep, its function, and whether it is even essential. Cool!

I stumbled upon the rabbit hole of unihemispheric sleep after watching this eerie video of sperm whales sleeping:

It appears that sperm whales undergo complete (bihemispheric?) sleep for 12 minute snaps, sleeping for just about 7% of their day, giving that whale the title of sleeping for the smallest percentage of their day out of any mammal (giraffes come in 2nd place with 8%).

This is why I love biology. Lets assume sleep is a biological necessity. Millions of years of evolution and adaptation has pulled this necessity in as many directions. From sleeping with half your brain at a time, or with the whole brain 7% to 80% of the day to everything in between. Biology is a healthy mix of ubiquitous phenomena and specialized solutions. Sometimes the hardest part is not clicking that one more wikipedia article all day.

1.1 Billion

That’s the number of heartbeats in every animal’s lifetime*. Don’t believe me?

Let’s consider an extreme comparison. A mouse can live for 3 years, and has a heartbeat of about 670 beats per minute. There are 525600 minutes in a year (365 days/year * 24 hours/day * 60 minutes/hour). So, that’s 3 years/lifetime *525600 minutes per year * 670 beats/minute ≈ 1.1 billion beats/lifetime. What about an elephant? They can live up to 70 years and have a heartbeat of about 30 beats/minute. 70 years/lifetime * 525600 minutes/year * 30 beats/minute ≈ 1.1 billion beats/lifetime. Woah… what?!

Ok, ok… you probably noticed that those “equals” signs are actually squiggly “approximately” signs, and if you did the math (you should!) you would see that they are both a little off from exactly 1.1 billion. But still, they are damn close. What gives? Why would the number of heartbeats be an invariant property of the animal kingdom? Let’s dive a little deeper.

The answer lies in allometric scaling, or how different properties of life scale with the body mass of organisms. It turns out that the power (energy per time, metabolism) required to support a given unit of mass of an organism scales with the mass of that organism to the (-1/4) power- meaning that smaller organisms use energy at a faster rate per unit mass than larger organisms. Other rates, such as breathing rate and heartbeat rate, also scale with bodymass^(-1/4). Lifespan, on the other hand, has been shown to scale with bodymass^(1/4). If you want to find how the lifetime total beats scale, you can multiply those two together (beats/time * time = beats). Bodymass^(-1/4) * Bodymass^(1/4) = Bodymass^0, which is always 1, meaning that the total beats is invariant of bodymass! More on allometry and metabolism in later posts. And maybe I’ll learn how to show equations in wordpress someday.

This paper (which probably takes into account more than the 2 points I used above) cites the total number of heartbeats in an animals lifetime as 1.5 billion.

Now, given this number, can we backtrack and use the relationship to see how long humans are predicted to live? Given a certain heart-rate, how long would it take us to use up our 1.5 billion?

lifetime

R code:
curve(1.5e9/(x*525600), xlim=c(40,100), lwd=5,
ylab=”Lifetime (years)”, xlab=”beats/minute”);
abline(v=60, col=”red”);abline(v=70, col=”red”)

If an animal beats its heart between 60 and 70 times a minute, it would use up its 1.5 billion beats in around 40-45 years. Is this a ballpark estimate of a human’s lifetime in the wild? (Aside: if you take the 1.1 billion heart beats derived from mice and elephants and assume a heart-rate of 70 beats per minute for humans you get 29.9 years!)

Now, don’t worry. Humans have found amazing ways to increase their lifespan, and it’s not like everyone has a set number of heart beats to get through before it’s all over. This is just an interesting result of looking at metabolism and ecology – and what’s even more interesting is looking at the animals that stray from the predictions.

*That’s about the predicted number of heartbeats in an average organism’s lifetime