Sea slugs with disposable penises…or is it “penes”?

For a species of sea slugs (or nudibranchs) that calls the Pacific Ocean home, penises are apparently disposable. In fact, disposable penises are a natural part of sex for them. That’s according to a paper published recently in the journal Biology Letters.

Scientists first discovered this bright pinkish orange slug — called Chormodoris reticulata for the latin speakers out there — in the 1800s. Many sea slugs are simultaneous hermaphrodites, so have both both male and female parts, so to speak. Also, in terms of the female bits, they typically have two pouches to store sperm — one of which can destroy sperm. So, they can mate with two males and pick with sperm stash to dump. In the human world, we might call this the purest form of rejection, but in animal behavior terms, it’s called “female choice”.

Lots of sea slug species mate in weird ways, so it makes them an interesting group for animal behavior scientists to study. In this case, a team of Japanese researchers went scuba diving to collect Chormodoris specimen during their mating season — in 2005, 2006, 2009, and 2010. Back in the lab, they stuck the slugs in tanks to watch what happened. They either paired two slugs that had been isolated for 24 plus hours, or stuck an isolated slug in a tank with one that had recently mated. In addition, to the observation, they took photos and tissue samples of the slugs’ reproductive layout.

So, based on their study here’s how this particularly brand of kinky sea slug sex works: the slug has a really long penis that’s curled up inside it’s body, with a little bit hanging out. When two slugs are ready to get it on, the little bit hanging out elongates and develops prickly spines on the end. After either seconds or minutes of sex, the end of the penis falls off. It takes at least 24 hours for a new “penis” to uncurl from the spiral section inside the body, but then they’re ready to go at it again. A slug can do this up to three times, and this particular species is the only organism in the world that can chuck it’s penis and mate again 24 hours later. (Other slug species drop their penises after mating season is over, but they have a much longer time to replenish).

Weird sex happens all the time in the animal world, so what makes this particular instance a big deal. Sexual selection rarely happens with hermaphrodites — they have the best of both worlds, so they’re all kind of on an equal playing field. But, because it takes 24 hours for the slug to bounce back, replenished slugs have the advantage.

Smithsonian does a nice job of summing it all up, here.


Chestnuts galore: Happy 30th, TACF!

This year marks the 30th anniversary of the American Chestnut Foundation — a group of chestnut enthusiasts and academics who’ve been stalwartly trying to revive the species since it’s decline in early 20th century. It might surprise young’uns like me to hear that chestnuts once comprised a quarter of eastern forests, which if you think about it is a whole lotta trees. That all changed when a fungus commonly called chestnut blight hopped aboard nursery exports from Asia, and spread across the entire chestnut range within 40 years.

At the end of last summer, I visited TACF’s research farm in Meadowview, a wide part of the road in southwestern Virginia. It was part of a feature article that I wrote for Nature on how TACF and other chestnut restoration efforts are starting to see results. The main goal at Meadowview is to breed an American tree with the right selection of genes from Chinese chestnut to provide resistance to the blight. (Unlike their American counterparts, Chinese chestnuts can survive the blight.) It took them a little under 25 years to do this, but they’ve started to export their chestnut breeding pipeline to local TACF chapters across the US.  I took some pictures while I was there:

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The other side of the Chestnut revival story begins with researchers at SUNY in upstate New York, who have developed genetically modified American chestnuts — American chestnut trees with candidate resistance genes from other chestnut species or other plants. Last March, a test plot of gm chestnuts was planted at the New York Botanical Garden — right across the street from where the blight was first discovered at the Bronx Zoo. In August, I went up to NYC to visit a friend, and of course, I dragged her on a side trip to NYBG to see their baby chestnuts.

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It might seem bleak from an outsider’s perspective, but perhaps one day chestnuts — maybe even genetically modified chestnuts — will comprise eastern forests once again. For more background, here’s my piece. And, if you’re super curious people have written books about this saga (American Chestnut: The Life, Death, and Rebirth of a Perfect Tree does a great job portraying the colorful cast of characters involved, and then apparently Barbara Kingsolver based a character on TACF’s chief scientist in her novel Prodigal Summer.)

Image Credits: HMT.

The Salt’s Top Posts Of 2012

Credit: Stephan Kuhn/Creative Commons
Credit: Stephan Kuhn/Creative Commons

One of my stories made the 2012 top ten list for NPR’s fabulous food blog, The Salt.

The piece actually ran last Friday, so it’s fairly recent. It’s about the debate over how humans evolved lactose tolerance — quite the mystery in the scientific community. Basically, 10,000 years ago most babies could drink milk because they had the gene for lactase, but the gene turned off in adults. Milk and dairying came with ancient agriculture, and several mutations for lactose tolerance became more frequent — people were passing them down to children. But if milk gave them diarrhea, then what made them drink it, and what gave milk drinkers a survival advantage? Turns out the answer is a bit of a can of worms. For more on that, here’s the original story. It ranked #3 on the list, so not too shabby.

And now…*celebratory dancing*!

Sea cucumber gut slime may be killing the GBR

Sea Cucumbers are like the crappy vacuum cleaners (the ones that spit out half the dirt they take in) of the ocean, and I mean that in the best possible way. They trudge along the sea floor like the gigantic slugs that they are, basically eating a lovely stew of sand and rocks and leaving it up to their digestive tracts to filter out the edible stuff. These cukes then proceed to poop out the not-so-edible stuff (the hence the crappy vacuum analogy) for other organisms to use or munch on. (Yay nutrient cycles!) But, thanks to ocean chemistry getting increasingly unbalanced for a multitude of unsavory reasons, their role as ocean floor recycling bins may be dissolving coral reefs, at least according to a study published back in late December in the Journal of Geophysical Research. In the course of their digestive antics sea cukes secrete acid compounds to dissolve the carbonate-based sand, spilling a whole bunch of soluble carbonate minerals into the water. But, what the heck does that have to do with reef building…

Brief Digression on How to Build a Coral Reef: The primary component of a coral reef is calcium carbonate (CaCO3). That goes for both the coral and the surrounding sand a rubble that falls to the ocean floor and fills up the crevices and holes between rock and coral. Most organisms that live on a reef either add to or absorb CaCO3 from the surrounding environment. In a healthy reef, there’s balance between CaCO3 getting absorbed into the reef and CaCO3 getting released by orgs like sea cucumbers.

….Marine scientists use this to measure how healthy a reef is. So, when there’s not a lot of CaCO3 in the water, the reef is growing aka healthy. And vice versa – too much CaCO3 means something’s out of whack, and in this case, sea cucumbers could be contributing to reef erosion. But, it’s by no fault of their own, increased ocean acidity and warmer waters (aka thermal stress) make it harder for other organisms that live on the reef to turn soluble CaCO3 into solid CaCO3.

Brief Digression on Ocean Acidity: As with most environmental issues these days, the main culprit behind the world’s oceans getting more acidic is the ridiculous amount of excess CO2 in the atmosphere (thanks coal, oil, and gas!). All that carbon dioxide gets absorbed by the world’s oceans; combine CO2, water, and carbonate ions, and (poof!) sea water gets more acidic. Only slightly kidding. Don’t believe me, check out NOAA’s unusually informative website.

In this particular study is that they looked at a specific section of the One Tree Island Reef area of the gigantic Great Barrier Reef creatively title DK13 and collected sea cukes to study in a lab setting. Although it’s name might cause one to think otherwise, One Tree Island does in fact have more than more form of vegetation. DK13 is oddly popular among sea cucumbers, so the research team, lead by Kenneth Schneider of the Carnegie Institution, wanted to find out if they could somehow be contributing to the higher calcium carbonate levels. They collected a swath of animals (Stichopus herrmanni and Holothuria leucospilota) to study how sea cuke digestion changes sea water in the lab and found an alarming amount of CaCO3. One could argue that the reef itself is producing this excess CaCO3, but it that were the case you’d expect to see the reef getting bigger, which it’s not. The same research group previously found that the DK13 was dissolving at night, and they estimate that sea cucumbers produce about half of the carbonate released during the night.

Second cousins of starfish and sea urchins, sea cucumbers enjoy slurping up food with their 8 to 30 tentacle-like feet, ensaring their enemies with slime thread, and breeding both sexually and asexually. Ow ow. CREDIT: Carnegie Institution/Dr. Aya Schneider Mor.

Obviously, scientists at Carnegie aren’t just hating on defenseless sea cucumbers – lead author Schneider said, “Although sea cucumbers may play a part in reef dissolution, they are also an important part of an incredible marine environment.” For the non-chemically inclined, this might sound like bad science (especially since the press release makes it sound like sea cucumbers are making the water more acidic, which would be kind of hard given that CaCO3 is basic). The fact that the water is getting more basic is good because it might stave off ocean acidification in the long term, but at the moment, understanding how sea cucumbers could be damaging Australia’s Great Barrier Reef. As Mr. T would say, I pity da fool who messes with ocean chemistry.

For a more positive take on sea cucumbers: here’s a study from last February that aims to use these “over-sized slugs” to save the world, one fish farm at a time, in addition to transforming British gourmet cuisine. “Next on Jamie Oliver, how to prepare sea cucumber en flambe in the nude…” Cheerio!

Oh the things a curious Dane can do with a used CT scanner…

Recently, there’s been a lot of ho-ing and hum-ing about recreating stradevarious violins and discovering the medical secrets of mummies from of all things CT scans. But, WaPo finally gives us a look at one of the guys behind the curtain: the Smithsonian’s Bruno Frolich.

“Oh, the things Bruno Frohlich can scan. Ancient whale skulls. Smashed human ones. Stradivarius violins. Violas. Cellos. Guitars. Stringed instruments from Mongolia. Apollo spacesuits. Eagle feathers. Mummified birds from Egypt oddly missing their heads. Dinosaur leg bones, fossilized. Thigh bones, hip bones, arms bones, teeth. An infant’s iron casket dug up in the District. Live turtles. Dead crocodiles. Mummy after mummy from Egypt. And one from Peru. The Smithsonian Institution owns 137 million things. Over the past 15 years, Frohlich, it seems, has scanned them all. Okay, not quite. But if he had enough time, he would. ‘This is my hobby,’ Frohlich says of his job.”

What a cool dude. Click to read the excellent article by Brian Vastag.

Found: fossils of ancient hairy mammal in Tibet

A team of scientists from the U. S., China, and Finland has uncovered a fossilized woolly rhino in the western Himalayas of Tibet. This is hardly the first woolly rhino that scientists have unearthed (in fact indigenous people of Siberia have been digging them up for ages). What makes this particular specimen of the Cousin It of prehistoric mammals particularly significant is that it’s older than all the others.

Back in 2007, the team set out for the Zanda basin of the Himalayas because of the plethora of fossils it had yielded in the past. They found a complete skull and lower jaw of an ancient mammal that stood an estimated 6 feet tall and 12 to 14 feet long (so about the size of a Ford Explorer, but less fat). This animal had some pretty awesome horns – one on the tip of its schnauzer at 3 feet long, and another smaller one between the eyes. In other words, it’s pretty similar to the modern rhino….but with lotsa hair.

Artistic reconstruction. CREDIT: Julie Naylor.

Originally, scientists thought that woolly rhinos appeared at the beginning of the Pliestocene era slash the last Ice Age slash about 2.6 million years ago. But, the Zanda fossils (termed Coelodonta thibetana sp.) are close to 3.7 million years old, which puts them in the Pliocene before the last Ice Age got started. Since they lived in the harsh environment of Tibetan mountains, these primitive woolly rhinos were preadapted with their shaggy dos to the cold and didn’t freeze their butts off when the world turned into an ice cube (slight exaggeration, I realize).

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Floozy beetles prevent harms of inbreeding

Male Flour Beetle: “Woman! Why are you hooking up with Jeff from the hardware store?… And Bob the Doctor?…and Ted the investment banker?”

Female Flour Beetle: “Sorry, Jerry, but you’re sperm’s just not genetically compatible.”

In the September 23rd issue of Science, researchers across the pond at the University of East Anglia found that inbred populations have a natural increase in female promiscuity to thank for preventing the harmful effects in offspring that come with getting it on with one’s cousin.  Females actually take on more mates to screen out sperm from males that aren’t a good fit genetically.

For awhile, scientists have been wrestling with the evolutionary enigma of why some girls are so darn trampy. Although fairly rare in humans (to my knowledge?!), polyandry – where multiple males fertilize a female’s eggs – is commonplace for a wide variety of organisms from chimps to sea urchins. However, in a lot of these situations, things don’t turn out so great for the female. Hence, the enigma.

Using red flour beetles as their model species, the Brits set up inbred and non-inbred mating groups. They found that females who hooked up with just one partner only produced about half as many surviving offspring as those who mated with five males. The Brits double checked for male infertility, but found nothing. So, the only other explanation was that those guys just didn’t have the most “genetically compatible” sperm aka they were too closely related. The scientists then took it a step further and manipulated non-inbred populations to start inbreeding. Sure enough, after about 15 generations, the females started getting frisky and changed their mating patterns. They’re still working on how exactly the females weed out the bad sperm, but…

Moral of the story: Genetic diversity is super important, and a species will go to to great lengths to preserve it.  And, don’t hook up with your cousin, even if you’re a beetle.

All in the title: Marilyn References

Some Like It Hot: The Influence and

Implications of Climate Change on Coffee

Berry Borer (Hypothenemus hampei) and

Coffee Production in East Africa

I love it when journal articles make completely random popculture references. This gem of a title is from the most recent issue of PLoS ONE. So in this scenario, are Tony Curtis and Jack Lemon coffee berry borers? And is Marilyn Monroe climate change?

There’s a spanish version of the abstract, and for some reason, I keep picturing Tony Curtis in drag reading it to me.

Glow-in-the-dark kittehs fight AIDS

CREDIT: Mayo Clinic

A group of physicians, virologists, and veterinarians at the Mayo Clinic and colaborators in Japan have taken what might seem like an unorthodox approach to fighting aids: genetically modified, glow-in-the-dark cats (!). Published in the most recent issue of Nature Methods, the study produced cats with intrinsic immunity to Feline AIDS, an epidemic among domestic cats, in hopes of using similar methods to fight the AIDS epidemic in humans.

They’re using what’s called a “genome based immunization strategy,” which is kind of like vaccinating your genome. Both humans and cats lack important proteins called restriction factors to fight HIV and FIV. So, the mayo team found a way to insert a gene from rhesus monkeys that produces immunodifficiency virus fighting restriction factors into a cat’s genome. Before the eggs were even fertilized, they shot them up with a gene eloquently named TRIMCyp. They tacked a jellyfish gene on, so that they would be able to see if the monkey gene was expressed. More specifically, they used the gene that codes for green fluorescent protein, which makes jellyfish glow underwater. (Part of me thinks that last bit was partially just for the awesomeness of making fluorescent cats, but I realize that scientists have been making stuff glow ever since they figured out what green fluorescent protein does.) The end result: cats that had the resistance gene, glow green under blue light.

LiveScience has an awesome photo gallery of adorable highlighter-colored cats.

The next step for the researchers will be to expose the kitties to FIV, and see if it works.