Posts Tagged ‘Animals’

Exploring the blurry line between colony and individual

// August 3rd, 2011 // 1 Comment » // The Realm of Bizzare

I found this great post on the Portuguese man-o-war, known as the bluebottle in Australia, over at Deep Sea News the other day. It’s eating a fish!

The post also said:

Remember this species is colonial and made of four different polyps or zooids, working in unison and dividing labor. The bladder is a single polyp called a pneumatophore. The long tentacles are dactylzooids used for fishing. The dactylzooids bring the fish up to another set of zooids, gastrozooids, responsible for digestion. Last, there is set of zooids, gonozooids, in charge of reproduction.

So it looks like a jellyfish, but it ain’t. It’s a colony of four specialists working together, each with their own nervous system but incapable of living by themselves.

Bluebottle on Woolongong Beach, NSW. Image by Fiona Wilkinson

As I was doing a bit of research about bluebottles and how they sting even when dead and dried up, I came across an interesting question. How do they reproduce? If the gonozooids are responsible for getting jiggy with it, don’t they just make more gonozooids? Where do the rest of the polyps come from?

Well, no one really is a hundred percent sure. I guess that’s fair enough, studying a swarm (a navy) of man-o-wars during mating season doesn’t sound too good. But here’s what they think.

A gonozooid from one man-o-war will make sperm which combines with an egg from another man-o-war gonozooid. Hey presto, you’ve got fertilisation and one embryo – which will become the bladder polyp at the top. That embryo divides several times, then reproduces asexually to make more zooids, which bud out of it. The budding polyps will become either tentacle, digestion or reproduction individuals.

That’s where I got confused. Does this mean that each of the zooids actually come from a single polyp? Are they just differentiated forms of the original polyp, specialised for their particular role? How is this different to a human embryo producing heart cells?

One explanation uses phylogenetics – comparing organisms to see how similar and different they are. Each zooid is similar to solitary Cnidaria (the phylum that includes jellyfish, coral and bluebottles), so can be considered an individual in its own right and a bluebottle as a colony.

But if we define an individual as something with similarity to other individuals, then all the cells of a multicellular organism would be individuals. Are individual humans really colonies of individual human cells? Really, the microbes on and in you outnumber your human cells 10 to one, so you’re more like a walking microbial factory anyway.

White poplars, a kind of aspen, form clonal colonies. Image by Jacob Halun

I think we have a very human-centric model for defining individuals, which is not surprising really. But most species on the planet don’t reproduce like we do, the boundaries between individual and colony are much less clear.

Take aspen trees, which can grow by seeds (sexually) or by underground runners which sprout a tree-clone (asexually.) Over time the runners can decay separating the trees. How can we tell if the trees are individuals or clones, and if we can’t, how do we study adaptation and natural selection?

Tasmania has these Huon pines that are the oldest genetically identical stand of trees which has lasted 10,000 years. Each tree lives about 2,000 years, but the original tree renews itself through genetic clones. Tassie also has the oldest genetically identical plants, clones of King’s lomatia estimated to be at least 43,000 years old.

Strawberries do it too, as do fungus. A single specimen of Armillaria solidepes was found in Oregon the size of 1,220 football pitches and estimated at 2,400 years old. It’s one of the largest organisms in the world.

Where does the individual end and a colony begin? Looking at all the bizarre stuff out there, I can’t help but wonder if we’re the weird ones.

ResearchBlogging.org

Clarke, E. (2010). The Problem of Biological Individuality Biological Theory, 5 (4), 312-325 DOI: 10.1162/BIOT_a_00068

Read it at the homepage of Ellen Clarke

Biodiversity weekend at Questacon

// September 10th, 2010 // 2 Comments » // Science Communication

This here is Charles Darwin studying some stick insects. This vision greeted me in the entrance hall of Questacon, Australia’s national science and technology center. The insects were crawling all over this guy’s face. He’s one of the very talented Excited Particles who are, as their name suggests, particularly excited about science. Sometimes fire. But then, who isn’t excited by fire? They also do highly entertaining science shows.

This weekend, Questacon are holding an event for the International Year of Biodiversity. There’s critters from the zoo, aquarium and reptile sanctuary, and specialists on native Australian plants. If you’re in Canberra (or Sydney, it’s not that far) check out the program. If not, don’t die of FOMO.

It’s getting close to the end of the year, so make the most of the biodiversity while it’s still hot. Next year’s offerings are the International Year of Forests (snore) and the International Year of Chemistry (yippee!!!) In fact, they have also have a weird year that started in August and is running till August 2011 called the Year of Youth, which gets young people involved in making important decisions about the world. Sounds good, I think.

Man I’m excited about the Year of Chemistry. More excited than a particle, I’d wager. We should make us some old school explosions! I’ll start hoarding the gunpowder now.

Hallucinogenic drugs, animal studies and explosm

// May 18th, 2010 // 3 Comments » // Drugs, Just for Fun

So I have had a really busy week in the lovely sunshine coast, and haven’t had a chance to track down the quality science content you know and love. Instead, I have comics of drugs.

WAIT!!! THIS IS SCIENCE! Because sometimes scientists give hallucinogenic drugs to animals to see what happens to them, and to find out how the drug works. Studying hallucinogens can give insights into how the mind works and manages itself.

There are a few famous cases of animal drug studies. The first is the spider web experiment, where spiders were given LSD, caffeine, cannabis or mescaline and the resulting webs were photographed. Another one is the elephant on acid, which happened in the 60’s (or 70’s) when LSD was new and being tried on EVERYTHING. They tried giving it to an elephant at about 400 times the human dose to see if it would go into musth, if it did it would prove LSD induced a kind of psychosis. The elephant didn’t go into musth, it actually died. And they were in a zoo and everything, not cool.

So here are the drug comics. Enjoy!

Cyanide and Happiness, a daily webcomic
Cyanide & Happiness @ Explosm.net

Cyanide and Happiness, a daily webcomic
Cyanide & Happiness @ Explosm.net

Cyanide and Happiness, a daily webcomic
Cyanide & Happiness @ Explosm.net

Oh Cyanide and Happiness, how I love thee!

Catching cancer part one – HPV infection versus the face of Tasmanian Devils

// January 1st, 2010 // 2 Comments » // How Things Work, The Realm of Bizzare

This post and the next have been bubbling in the pipeline for some months now, and were finally prodded to the open by this post by Carl Zimmer about the facial tumour disease wiping out Tasmanian Devils.

So what’s the deal with the face-cancer first up? (Sidenote: You’d be surprised how many people have found my post about Cordyceps by searching face fungus. I hope you googlers don’t have face fungus, that makes me sad.) Anyhoo, Tassie Devils are the world’s largest carnivorous marsupials and are only found in Tasmania, this makes them very special little critters. They are also violent and bitey mofos, and they’re pretty ugly to boot. Here’s one.

Okay, that one’s actually cute. Try this one.

Like big teethy rats.

Tasmania ain’t a big place, so if a male meets a sexy female devil and she’s not a sister, she’s probably a cousin. That means there’s not much genetic diversity between individuals. Enter the cancer. The cancer infects the face, and Tasmanian Devils have a nasty habit of biting each other on the face, which passes on the cancer. It’s an infectious tumour! This is very VERY rare, the only other one I know is Stickers Sarcoma which infects dogs, we people don’t catch tumours from each other. Cancer researchers need to be super-sterile in teh lab to protect the cancer cells, not themselves.

In the Tassie’s case, their DNA is so much the same, I bet if you asked them if they wanted icecream they’d both say yes the cancer cells feel at home in a new host, and their inbred immune system doesn’t notice them. Cancer cells do, after all, survive the immune system by looking like a normal cell.

It’s all bad news for the Tasmanian Devils. Cancer is a hard disease to cure for the same reason it evades the immune system – it looks like a normal cell. Killing it often involves collateral damage, and it’s a shaky balance to kill the cancerous cells faster than the rest of the body. Treatments are tailored and expensive – and it’s damn hard to give radiotherapy or chemotherapy to a wild animal. On the other hand, all these devils have the same cancer cells, if we COULD find a way to target them specifically we would cure them all. It might be an easier cancer to treat than the human varieties.

An intriguing question – is this a new lifeform? The cancer cells are genetically different to the Tasmanian Devil cells, they have the ability to evolve, grow, move between hosts. Are they a single-celled parasite, an infectious microbe in their own right? Where do we draw line between a mutated cell and a new species?

Will it infect us too?

Not sure about you (each to their own), but I don’t make a habit of biting people’s faces. Plus we are a pretty spread-out species with plenty of laws and morals against inbreeding. So I think we’re safe.

But we do have something that causes cancer, and it is VERY infectious. It’s a virus called HPV, and you’ve probably already been infected by it. You probably wouldn’t even know it. That’s the topic for tomorrow. Check out part two.

Cheap date, grim reaper and swiss cheese – the world’s coolest gene names

// December 3rd, 2009 // 2 Comments » // Jibber Jabber, Just for Fun, Sex and Reproduction

0507-hello_my_name_is1

I studied biochemistry at University, and I remember spending hours copying pathways, reading and rereading textbooks, then summarising, checking, drawing, testing, making mnemonics, in short EVERYTHING I could do to help me memorise things. There is a lot to remember in biochemistry, and a lot of words which don’t mean much that have to go in the right place. JAK activates JEK activates MEK which activates an enzyme which travels to the nucleus and binds to blah which attaches to blah region of the DNA and has the effect of increasing glucose absorption. Or something. Frankly I can’t remember anymore, and I’m damn glad I don’t have to try.

Meaningless acronyms are an annoying part of science, and of any job really. At work I talk about getting a tvc cadded, matching the key to the clapper and ingesting it – to anyone who hasn’t done TV advertising this is complete jibberish. Biochemistry is really no different – if you don’t know much about it, it’s because no one has explained it to you properly using normal words.

This post is not about normal words. Screw normal words! This is about the awesome, the spectacular, the creative and the downright weird.

These are some of the coolest names I have come across for proteins and genes, and a lot of them are found in the fruit fly Drosophila. Drosophila is the white lab rat of developmental science, it’s always the guinea pig because it reproduces REALLY fast, and creates multiple offspring in a single frenzy. Some other species (including humans) also get a mention in this list.

Tinman – Drosophila with a mutation to tinman develop with no heart.
Maggie – a mutation causes arrested development, in the Simpsons Maggie never ages.
Cheap Date – mutation causes Drosophila to be extra sensitive to alcohol. Another gene called Lush does the same thing.
Cleopatra – Cleopatra was killed by an asp, and interaction of mutant Cleopatra protein with the Asp protein is lethal.
Ken and Barbie – mutants (both male and female) lack external genitals.
Swiss Cheese – mutants have holes in their brain.
Grim Reaper – two separate genes, together they cause cell death.

For those biblically minded of us, there is Lot – mutants have more salt than usual, or Sarah – mutants are almost sterile, or Methuselah – mutants live extra long. Prefer Greek Myths? How about Ariadne, who showed Theseus how to get through the Minotaurs Labyrinth – in Drosophila, Ariadne mutants stop the axons of nerve cells finding their targets. Love Shakespeare (who doesn’t?), take Hamlet – which affects development of cells descended from IIB cells – “to be or not to be.”

Sometimes the names help us remember how things link together, take these names from Arabidopsis thaliana, a small flowering plant that’s like the Drosophila of plant genetics. Superman mutants have extra stamens in their flowers, while the Clark Kent is a milder version of the mutation, and Kryptonite suppresses the function of Superman.

Zebrafish have some neat ones too – including one-eyed pinhead, cyclops and squint – all important in the development of an embryo.

How about in humans? Well yesterday I talked about a spiky little protein called Sonic Hedgehog, which was originally found in, you guessed it, Drosophila, but which plays an important role in embryo development in humans. There’s not a huge number of genes with cool names in humans, and there’s a good reason for that. Imagine you had a child who was very sick and you met with the doctor, who looked at you seriously and said “I’m sorry, it’s genetic. Your son has a mutation in the Sonic Hedgehog gene.” There are a couple of others, like Tigger which is a segment of DNA which hops around into different locations

Those are my faves, but there’s plenty more out there. These are samples from My Favourite Gene Names and Gene Names by Organism, and I know there’s others that didn’t make the list. FlyNome has a searchable database of heaps of Drosophila genes and the story behind them. It’s almost worth getting into Drosophila research just for the cool names, plus imagine if you found a new gene and got to name it yourself… oh the possibilities…






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