Modern Biology
Muscle Disease Gene Identified in Fish
Bird Flu Mutation Risk
Platelets Help Tackle Bacteria
Untangling The Model Muddle
Cloning - The Good, The Bad and The Ugly
Unpacking the Human Genome Project
Does a Hot Mint Still Taste Cold?
Do Bald Men get all the Girls?
Why Plants Make Caffeine
Turning your Brain into Blood - How Stem Cells Work
The Microchimera Mixture
Forgetful Flies - A tale of two halves (of the brain)
The Smelly World of Mice and Men!
How animals develop from an embryo
Ricin : The Secret Assassin
Why drink Wine ?
Genetically Modified (GM) Plants
Big Fish, Little Sea
Something in the Air
What's On The Menu ?
What is the purpose of sexual reproduction?
Therapeutic Cloning, and Stem Cell Research
What is Living in my Mouth?
Genes for Bigger Brains
  Why Plants Make Caffeine
It's Monday again, and somehow I have managed to convince myself over the weekend that waking at 11 is justice, and the natural human way. But here it is, Monday 10:30 am, and I've been up for 5 hours already....

I think it's time for a coffee break. I rush around, juggling my workload until I can finally manage to fit in 15 minutes for a quick mug-full of that sacred, sacred Joe. But if I were a plant like Cocoa, Kola, Guarana, or Coffee, I wouldn't have had to make the time - I would already have the caffeine built in. Do these plants realize just how lucky they are? That is, of course, assuming that plants use their caffeine to get a buzz on.

In truth, scientists have only begun to guess why some plants produce caffeine. Caffeine is classified as a secondary compound which means it is not essential for the plant's survival. In fact there are many species of caffeinated plants with decaffeinated relatives (poor things), but, as a non-essential component, it can be harder to pinpoint exactly what the caffeine is doing there.

Chemically, caffeine is a methylxanthine. Many methylxanthines are used as pesticides both by humans and plants. It's possible, though not confirmed, that caffeine is used to poison herbivores and plant pests to discourage them from attacking that plant type again; that is, if they survive after metabolising the caffeine. But because caffeine is toxic to plant cells it's stored in specialised cell compartments called vacuoles which are rather like a medicine chest and keep the caffeine safely locked away from the rest of the cell contents until it's needed. Unfortunately this means that the plant doesn't get to enjoy the buzz from its own caffeine (assuming plants can experience a 'buzz'), but that's a necessary trade-off of having a toxic substance lying around.

So it seems that caffeinated plants are lucky to have this compound as part of their natural defences, but it doesn't deter all attackers. For instance, caffeine doesn't poison humans in the doses that we typically ingest (even a Monday morning dose), but it does cause addiction. It works by stopping the enzyme phosphodiesterase from breaking down a signalling substance called cyclic AMP (cAMP for short) and its close relatives. One of the actions of the stress hormone adrenaline is to increase the levels of cAMP in cells, so by preventing cells from breaking down cAMP, caffeine potentiates the action of adrenaline, and gives us a buzz. In even higher doses, and with prolonged use, it can trigger anxiety, muscle tremors, palpitations and fast heart rates, and profound withdrawal effects including headaches, inability to think clearly, and bad moods whenever you mistakenly switch to decaff !

Caffeine-containing plants may be safe from certain insects, vertebrates, bacteria and fungi, but they are preyed on by humans who love the rush it gives them. Not so lucky then, I guess? But there is a hypothesis that plants synthesise psychoactive compounds to target and manipulate humans in particular. In other words, if humans desire the plants, then they will cultivate them. The plants may get processed and eaten up by humans, but because they have been better cared for, they will be able to produce more offspring first. If this hypothesis is true, I think caffeine-producing plants should win whatever the highest international award is for human psychology.
Bigfoot: The Nitrogen Problem
A Traveller's Guide to Bed Bugs
A spider web's strength lies in more than its silk
Thai police bust Bangkok rare wildlife 'butchers'
Castaway lizards provide insight into elusive evolutionary process
Bouquet bargains trade off for life
18 endangered dolphins spotted off Borneo: WWF
Tiny primate 'talks' in ultrasound
Steroids control gas exchange in plants
Fossil cricket reveals Jurassic love song
Rhino dies after anti-poaching treatment in S.Africa
Lions adapt to winter at Canada safari park
Invasive alien predator causes rapid declines of European ladybirds
Not the black sheep of domestic animals
Coaxing a Shy Microbe to Stand Out in a Crowd
How the zebra got its stripes
Fruit flies drawn to the sweet smell of youth
FLORA AND FAUNA Genetic Rosetta Stone unveiled in Nature
Ultraviolet protection molecule in plants yields its secrets
Indian village relocated to protect tigers
Explosive evolution need not follow mass extinctions
Plants use circadian rhythms to prepare for battle with insects
Armenia culls wolves after cold snap attacks
The Developing Genome?
Tempur-Pedic Mattress Comparison
Chromosome analyses of prickly pear cacti reveal southern glacial refugia
Poachers slaughter hundreds of elephants in Cameroon
'Founder effect' observed for first time
A Blue Future For Global Warming
Hitchhikers guide to Science
The Art of The Barbecue
Lost your bottle?
A Crossword a Day keeps the Doctor at Bay
Bio-plastics: Turning Wheat And Potatoes into Plastics
Why Don't Woodpeckers Get Brain Damage?
Protein Origami: Pop-up Books & Nature's Polymers
The Science of Parasites
Synthetic Biology: Making Life from Scratch
Flies are creatures of habit
What is Love?
How do plants develop?
What IQ Tests Can't Tell You
What is the Weirdest Experiment Ever?
Humble Honey Bee Helping National Security
Southern Right Whales
The Ocean's Cleaners
Barnacles "mussel" in
Food Date Coding Decoded
Photorhabdus luminescens: The Angel's Glow
Evolution Through the Looking Glass
I'm a Civet: Get me out of here!
No Smoke Detectors in the Sea