Category: Biology

Gene Transfer from Algea to Sea Slug

The sea slug. "Elysia pusilla" by Katharina Händeler, Yvonne P. Grzymbowski, Patrick J. Krug & Heike Wägele - Händeler K., Grzymbowski Y. P., Krug P. J. & Wägele H. (2009) "Functional chloroplasts in metazoan cells - a unique evolutionary strategy in animal life". Frontiers in Zoology 6: 28. doi:10.1186/1742-9994-6-28 Figure 1F.. Licensed under CC BY 2.0 via Wikimedia Commons.
The sea slug. “Elysia pusilla” by Katharina Händeler, Yvonne P. Grzymbowski, Patrick J. Krug & Heike Wägele – Händeler K., Grzymbowski Y. P., Krug P. J. & Wägele H. (2009) “Functional chloroplasts in metazoan cells – a unique evolutionary strategy in animal life”. Frontiers in Zoology 6: 28. doi:10.1186/1742-9994-6-28 Figure 1F.. Licensed under CC BY 2.0 via Wikimedia Commons.

One of my students wanted to figure out how to make animals photosynthesize. Well, this article indicates that sea slugs have figured out how eat and digest the algae but keep the algal chloroplasts alive in their guts so the sea slug can use the fats and carbohydrates the chloroplasts produce (the stealing of the algal organelles is called kleptoplasty). To maintain the chloroplasts, the slugs have actually had to incorporate some of the algae DNA into their own chromosomes–this is called horizontal gene transfer and it’s what scientists try to do with gene therapies.

More details here.

Magnification ?.
Filamentous algae like the ones eaten by the sea slugs.

Sumac Berry Juice

Sumac berries.
A bunch of sumac berries on the branch.

Ripe, bright-purple sumac berries are quite astringent. Steep a ripe bunch in a quart or two of hot water for a few hours (or cold water for a day) and the result is a tart tea. Add a third of a cup of sugar to make a delicious juice. (Note: Poison sumac is not found in Missouri, but it has been identified in adjacent, eastern states, so be careful.)

Dandelion Season

Preparing the flowers for frying.
Preparing the flowers for frying.

The last two weeks have been peak dandelion season here in eastern Missouri, so I’ve been experimenting with the culinary uses of the flowers.

Dipped in batter and fried, the flower heads did not taste like much. Probably too much seasoning and too much batter. It was good advice to cut off as much of the green outer covering (the sepals) because they are bitter. However, if you cut too close to the base of the petals they fall out all over the place, which is good if you want to collect just the petals.

Dandelion flower fritter.
Dandelion flower fritter.

Collecting the petals only is great if you’re trying to make dandelion wine (I’m adapting the second recipe from here), except that I’m only using petals (2 quarts). I keep the same amount of sugar (3 lbs), oranges (4), water (1 gallon), and yeast (winemaker’s). This is the appropriate timing for this project since we just covered the differences between aerobic respiration and fermentation.

Two quarts (about 4 liters) of dandelion flowers for making a gallon of wine.
Two quarts (about 4 liters) of dandelion flowers for making a gallon of wine.

The Eggs have Arrived

After waiting an eternity (about two weeks) the Middle School business’ eggs have arrived.

Eight eggs in their packing.
Eight eggs in their packing.

We set up the incubator downstairs in the pre-school/Kindergarden classroom so Mrs. D’s kids will have the chance of monitoring them. The little kids will be responsible for turning the eggs, while the middle schoolers have set up a data logger and a couple temperature probes to keep track of the temperature in the incubator.

The incubator was provided by Ms. Mertz. It’s put together out of plywood with a 75 W incandescent light bulb as the heat source. Unfortunately there is a significant thermal gradient and although we salvaged a couple of computer fans for the purpose we did not get around to installing them –and more importantly testing them– in the incubator before the eggs arrived.

We’ll see how it goes.

Radiolab: The Extinction of the Dinosaurs

RadioLab has an excellent podcast featuring Jay Melosh, a geophysicist who specializes in impact craters, and who advocates the hypothesis that the entire extinction event that killed off the dinosaurs at the boundary between the Cretaceous and Tertiary (the K-T boundary) took place over a period of two hours. The asteroid impact vaporized the crust of the Earth where it hit (near the Yucatan peninsula) and blasted this rock gas into space. There it cooled down to create little glass particles that reentered the atmosphere. On reentry the glass burned up, but there was so much of it that it raised the temperature of the atmosphere by several hundred degrees Celsius. Anything near the surface (mostly the dinosaurs) was cooked, but anything living just beneath the surface could have survived.

DNA Models and Games

The DNA strand in this board game splits as players end up on different paths based on their choices in the game.
The DNA strand in this board game splits as players end up on different paths based on their choices in the game.

Ms. Mertz’s class is studying DNA–replication, translation, transcription, etc.–and she gave them the option of making a model or creating a game to test each others knowledge. There were some interesting projects:

A DNA strand modeled with the bases represented by colored marshmallows. Toothpicks connect the marshmallows along the backbone of the helices, while Twizzlers are used to show the bonding across the two DNA strands.
A DNA strand modeled with the bases represented by colored marshmallows. Toothpicks connect the marshmallows along the backbone of the helices, while Twizzlers are used to show the bonding across the two DNA strands.
The quiz questions in this board game are visible to all the players, which allows for more in-depth discussion of the answers.
The quiz questions in this board game are visible to all the players, which allows for more in-depth discussion of the answers.
Helicase (the cotton ball) splits the DNA double helix.
Helicase (the cotton ball) splits the DNA double helix.
Ms. Mertz helps a student with their research project on cloning.
Ms. Mertz helps a student with their research project on cloning.
The study of DNA and heredity offer great opportunities to study probability. In this case, a player has to traverse 80 squares by rolls of a single dice, and then answer a question from a card. If they get the wrong answer they do not advance, but if they pull a Go to Jail card they have to go back to Jail. If there are 20 cards and two of them send you back to Jail, what's the probability of anyone finishing the game?
The study of DNA and heredity offer great opportunities to study probability. In this case, a player has to traverse 80 squares by rolls of a single dice, and then answer a question from a card. If they get the wrong answer they do not advance, but if they pull a Go to Jail card they have to go back to Jail. If there are 20 cards and two of them send you back to Jail, what’s the probability of anyone finishing the game?

Blueberries in the Snow

Dr. Sansone and a parent volunteer, transplant blueberry bushes into the partly frozen ground.
Dr. Sansone and a parent volunteer, transplant blueberry bushes into the partly frozen ground.

Last weekend was not the optimum time for transplanting berry bushes. The top five centimeters of the soil was still frozen, and the air temperature was below zero Celsius with a cold breeze on top of it. However, we needed to get fourteen blueberry bushes moved, and, with a lot of help from some parents and a couple students, we were able to get the bushes and enough soil laid out to give them a good chance of success when the soil warms up.

Raspberry mounds protected by straw await warmer weather.
Raspberry mounds protected by straw await warmer weather.