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Mitosis stages of the Lily

Oliver — Sun, 06 Dec 2009 15:33:52 +0000

Interphase. The nucleus is visible.

Prophase. Chromosomes are starting to form.

Metaphase. The chromosomes align at the equator of the cell.

Anaphase. The two sister chromatids are separated.

Possibly metaphase or anaphase seen head-on. The chromosomes are possibly pointing towards the viewer.

Telophase. The spindle fibers are still visible between the two nuclei. The cytoplasm has not yet divided.

Background Information: Mitosis is cell division in eukaryotes. During mitosis the chromosomes are visible. Interphase is not considered part of cell division. The following stages are Prophase, Metaphase, Anaphase and Telophase.

Image Information: Higher resolutions are, unfortunately not available. A magnification of 400x was used to obtain these images. The cells were treated with a dye that has a high affinity for DNA.

Making a Hay Infusion

Oliver — Fri, 12 Dec 2008 22:20:18 +0000

It is possible to enrich microorganisms such as ciliates by making a hay infusion.

Materials: A hand full of hay, a large beaker, pond water, some milk

Method:

Take a hand full of dried grass or hay (free from pesticides or herbicides) and cut the grass into smaller pieces
Place the cut grass into the beaker and about 0.5-1 liter of water.
Add 1-2 drops of milk. The water will turn slightly turbid. The milk is food for the bacteria and they will start to reproduce. The ciliates feed on the bacteria and will also reproduce.
Let the beaker stand open for several days, protected from direct sunlight as this may result in overheating and the heat will reduce the oxygen concentration. Do make sure that the beaker receives sufficient light, though. Photosynthetic algae present in the pond water will produce oxygen.
Keep adding 1-2 drops of milk when the turbidity disappears. Bubble some air through the water at regular intervals (using an air-pump from an aquarium) or agitate the water a bit to enrich it with oxygen.
Replace the evaporated water.
Take some sample from the surface of the water (where there is oxygen) for microscopic investigation. If the water is agitated, then the microorganisms are (of course) not able to collect beneath the water surface.

Troubleshooting:

Problem: The water starts to smell.
Solution: This is normal. Bacteria are starting to decompose the hay and the added food. If bubbles start to appear though, then this is an indication that methane is formed anaerobically. This should not be and indicates that there is not enough oxygen in the water.

Problem: There are many bacteria but too few protozoa in the water.
Solution: Probably there was overfeeding. Add less milk and less hay. The bacteria multiplied too quickly and the protozoa could not keep up.

Problem: Nothing much seems to happen after a few days
Solution: Did you use chlorinated tap-water? Was the hay treated chemically?

Safety issue: You are cultivating unknown microorganisms. Potentially harmful bacteria could also be in the sample. It is therefore important to observe the rules of hygenics. Use this method at your own risk.

Growing Paramecia

Oliver — Fri, 12 Dec 2008 22:19:30 +0000

Paramecia are fresh-water ciliates that make excellent microscopic specimens. They are relatively large and therefore easily observable, even under low magnification. Pond water usually does not contain sufficiently high concentrations of them. For educational purposes it is necessary to enrich them.

Materials: Fresh pond water, wheat grains, glass beakers

Method 1:

Pour some pond water containing ciliates into the beakers and place 1-2 wheat grains into the water.
Wait for 2-3 days. The wheat grains will start to decompose and will seem to form a slimy layer around it. There should be thousands of ciliates in this slime. We have established a small food chain. Bacteria will break down the wheat grain. Paramecia will feed on the bacteria and reproduce.

Troubleshooting:

Problem: No paramecia have formed.
Solution: There were probably none in the original water sample. Paramecia and other ciliates can be found on the ground of ponds, in the slimy surface of rocks, etc. Include some of this material as well.
Solution: Did you use a complete wheat grain (with seed coat)? If you use rice or other polished cereals, then there are not enough nutrients available. The seed coat contains DNA and proteins (phosphates and nitrogen compounds) which are used by the bacteria.