Archive for the 'symbiosis' Category

Published by Diana on 20 Jan 2010

Dinoflagellates

A Tale of Two Flagella is written by Olivia Judson, one of the best science writers there is.

Dinoflagellates are single-celled organisms that make coral reefs possible; they have a symbiotic–mutually beneficial–relationship with corals that make corals grow faster. Corals with certain kinds of dinoflagellates can cope with warmer water better than corals without them.

But other dinoflagellates are bad news. Ciguatera, a nasty form of poison found in some fish, and parlytic shellfish poisoning, a nasty form of poison found in some shellfish, both are caused by dinoflagellates. Red tides (in which massive numbers of dinoflagellates accumulate rapidly in one area) kill many animals, including dolphins, turtles, and other endangered species.

Dinoflagellates are weird; they can photosynthesize, despite being mobile cells; they have taken over the chloroplasts (the sun-utilizing bodies within the cell) of other organisms. And their DNA is unusual too.

Read the article for more details!

Published by Diana on 05 May 2009

Thinking About Bees

It’s been a cool spring where I live in the Pacific Northwest. The cherry trees are late this year, and the tulips are so late that the Skagit Valley Tulip Festival, scheduled for April 1st to April 30th, has been extended two weeks, well into May. The tulips weren’t really blooming this year until this week, I’m told by friends who went up last weekend.

The Northwest apricot trees are starting to bloom as well, and the growers are starting to move the bee hives into the field to pollinate the trees. Without bees, there would be very little fruit on the fruit trees here in the Northwest. We need bees to pollinate the apricots and peaches and (of course) the Washington apples for which we are famous. We need bees to pollinate the grapes that are made into Oregon’s wonderful pinot noir wines.

African Honeybees, Photo by Jay Torborg

African Honeybees (Photo by Jay Torborg)

In fact, bees (and a few other insects) pollinate pretty much all of our fruits, vegetables, and nuts. (Grains are mostly pollinated by wind.) This link lists the plants that are pollinated by bees: Crop Plants Pollinated by Bees.

Pollination occurs when a bee picks up pollen (from the stamens of the flower) when visiting a flower for its nectar. Then, when the bee flies to the next flower, some of the pollen falls off onto the stigma (or stigmas) of the flower. The pollen is comparable to sperm–it is the male gametes of the flower–and the stigma is a tube that leads directly to the “egg” of the female flower. (Some flowers are both male and female; some are male; some are female. It depends on the kind of plant it is. Plant sex is complicated.)

When the pollen grain lands on the stigma, it sends down a tube to the egg, then sends the DNA down to the tube, and the egg is fertilized.

Once the egg is fertilized, the egg produces a seed and the fruit around the seed. Imagine an apple. The whole apple is there just to persuade an animal to eat the seeds inside the apple. There is all that sweet fruit surrounding the seeds. So the animal eats the apple, and swallows the seeds, and they travel through the digestive tract, and are eventually eliminated, along with a nice bit of fertilizer. (From a plant’s point of view, an animal is just a really good way to get your seeds spread around.)

But without bees, there’d be no fruit.

So when bees are threatened, it’s a really big deal. A few years back, beekeepers discovered that their bees were dying in large numbers. It was called Colony Collapse Disorder and of course scientists started studying it.

Unfortunately, we don’t really know a lot about Colony Collapse Disorder yet, but there are a lot of theories about what to do about making sure we have pollinators. The New York Times had a great column about it a while back: Treatment for Bee Plague.

And researchers at Washington State University say it might not be that bad: Bee experts say Colony Collapse Disorder might not be as bad as first thought. (I have to say that traces of seventy different pesticides sounds pretty awful to me, though.)

What can you do? Plant food for your local bees. Don’t use pesticides.

(Honeybees are actually not native to this country. They were brought here by the first colonists, because they were considered essential. There are native bees that pollinate our native fruits and vegetables, but they need to be encouraged. In the meantime, beekeeping–maintaining hives of honeybees–is a huge business here in the United States. Half a million hives are brought into California every spring just to pollinate the almond trees so that we can all have almonds.)

There are other great websites for more information on bees and how you can help them in your garden! This website will tell you good plants to plant at home for bees: Bee Gardens.

This is a good place to learn more about Colony Collapse Disorder: Plan Bee Central.