User:Shauna McManus/Notebook/Biology 210 at AU

Identifying the Algae and Protists of Transect #5

01/24/2015

Purpose:

The invention and perfection of microscopes has allowed scientists to discover and further their understanding of microscopic unicellular and multicellular organisms (Bentley, Walters-Conte, Zeller, 2015). These microscopic organisms, and all organisms, can be broken down into either prokaryotes or eukaryotes. Within eukaryotes, there are 2 main groups of unicellular organisms: algae and protists (Bentley, Walters-Conte, Zeller, 2015). If a sample from the Hay Infusion Culture is examined under a microscope, it can be predicted that both of these types of unicellular prokaryotes can be found living in the observed transect.

Materials and Methods:

Procedure I

The jar with the Hay Infusion Culture from the previous week was carefully brought over to the lab bench. The culture is considered an ecosystem with many different types of niches. Careful observations were made about the appearance and smell of the culture. Then, samples from 2 different niches ¬– the top film and the debris that had settled on the bottom – were taken for microscopic observation. Wet mounts were made from these samples, and then were observed under a 10x and then 40x microscope lens. Three different organisms were observed from each niche and were then identified using a dichotomous key. Pictures of the organisms were then drawn, and careful notes and measurements were taken.

Procedure II

After this was completed, prep work for the following lab was done. Four tubes, each containing 10 mLs of sterile broth, were obtained. The tubes were labeled 10-2, 10-4, 10-6, and 10-8. The four nutrient agar plates and four nutrient agar plus tetracycline plates (+tet) were obtained. One plate from each of these 2 sets of plates was labeled 10-3, 10-5, 10-7, and 10-9. The lid was placed on the Hay Infusion Culture and then it was swirled to mix the contents. Then, using a 100-microliter micropippeter, 100 µl of the culture was added to the broth tube marked 10-2. The tube was swirled. Then 100 µl from the 10-2 tube was added to the 10-4 tube. That tube was swirled, and then 100 µl from the 10-4 tube was added to the 10-6 tube. Again, the contents of that tube were swirled, and then 100 µl from the 10-6 tube were added to the 10-8 tube. Once these dilutions were complete, they were plated on the agar and agar plus tetracycline plates. 100 µL of the 10-2 dilution was pipetted onto the agar plate marked 10-3 and then 100 µl was pipetted onto the +tet plate marked 10-3. The sample was then spread on the respective plates. This procedure was then repeated four times, with the 10-4 dilution on the 10-5 agar and +tet plates, the 10-6 dilution on the 10-7 agar and +tet plates, and the 10-8 dilution on the 10-9 agar and +tet plates (Figure 1). Figure 1

Data and Observations:

After sitting for one week, the culture was very different than it had been at the start. The culture seemed to have divided into different sections. All of the dirt had settled to the bottom. There were bits of mulch and vegetation floating in the middle. A thin, scab-like layer stretched across the culture on top of the liquid (Figure 2). This layer was mainly a light brown, although it had several large patches of a fuzzy looking white material, which was possibly mold (Figure 3). Figure 2 Figure 3

There were no green shoots anywhere. The culture smelled terrible, with a bit of a rotting scent. 2 of the 3 organisms observed from the wet mount of the top of the culture were identified with the dichotomous key, while the 3rd remained a mystery. The first was clear, ovular, motile, about 60µm long, and had visible cilia and internal structures, as well as an indented oral groove (Figure 4). This was identified as the protozoan Colpidium.

Figure 4

The second was also clear, had an eggplant-esque shape, cilia, and was about 180 µm (Figure 5). This was identified as a paramecium protozoan.

Figure 5

The third one was not possible to identify with the given dichotomous key. It was clear, ovular, 110 µm long, and had cilia on both of the shorter ends (Figure 6).

Figure 6

Similarly, only 2 out of the 3 organisms from the wet mount of the bottom of the culture were identifiably with the dichotomous key. The 1st one was a very long oval, covered in cilia, 210 µm and moved in a corkscrew motion (Figure 7). It was identified as the protozoan Paramecium multimicronucleatum.

Figure 7

The 2nd one was also covered in cilia, and was ovular, but was a shorted oval shape – only about 80 µm long – and was a very dark green color, indicating that it carries out photosynthesis (Figure 8). It was identified as the protozoan Paramecium bursaria.

Figure 8

The 3rd one could not be identified with the provided dichotomous key. It was very small – only 10 µm long – was clear, spherical, and was constantly vibrating (Figure 9).

Figure 9

Conclusions and Future Directions:

All of the organisms that were identifiable with the dichotomous key were protozoa; we were not able to identify any algae. This does not necessarily mean that there were not any algae species living in the culture. Next time it may be better to make a wet-mount slide from the middle section of the culture, or to keep examining the wet mounts from the niches at the top and bottom of the culture to potentially identify any algae. The protozoa that were identified meet all the needs of life. For example, when looking at the Colpidium, the oral groove allows the organisms to eat, and therefore to obtain energy from, other organisms, meeting the first requirement of life (Freeman, Allison, Quillin, 2014). The organism is unicellular, and so the observable organism in itself meets the second requirement of being made up of membrane cells (Freeman, Allison, Quillin, 2014). The Colpidium was able to survive in the culture, even though it was not its normal or original environment. This demonstrates that the organism was able to process information about its environment and adjust to maintain a stable internal environment, and thus still survive in the culture, which meets the third need of life (Freeman, Allison, Quillin, 2014). The fourth requirement is replication. Although replication of the Colpidium was not directly observed, Colpidium has been observed to reproduce asexually through cysts (Cutler, Crump, 1924) thus meeting the fourth requirement. The last requirement of a living organism is that it is the product of evolution. Again, this is not something that was directly observable in the lab, but it is something that has been demonstrated over time (Cutler, Crump, 1924). Therefore, Colpidium meets all five needs of life. It is possible that if the culture had been left for a longer period of time than one week, such as, for example, two months, there would be differences. For example, Colpidium is often a source of food for various paramecium species (Cutler, Crump, 1924, so it is possible that there would be a lot less Colpidium organisms, because they would have been eaten, and a lot more paramecium species because they would have had a source of energy. This is also true of other species or organisms as well. Next week the agar and +tet plates will have hopefully grown bacteria cultures. We will be able to analyze these bacteria to identify different species present in transect #5.

References:

Cutler, D. W., Crump, L. M. 1924. The Rate of Reproduction in Artificial Culture of Colpidium colpoda. National Institutes of Health: Bethesda, MD.

Bentley, M., Walters-Conte, K., Zeller, N. 2015. A Laboratory Manual to Accompany General Biology II. American University Department of Biology: Washington, DC. 19-21.

Freeman, S., Allison, L., & Quillin, K. 2014. Biological science (5th ed.). Pearson: Glenview, IL. 2.

-SM

Observing a Transect

01/22/2015

Purpose

Life on Earth is incredibly diverse. While no one knows for certain how many different species exist, scientists predict that there are anywhere from 10 to 100 million different species (Freeman, Allison, Quillin, 2008). This incredible diversity can be represented on a small scale, in a contained ecosystem. An ecosystem, or transect, is a community that contains both biotic and abiotic components (Bentley, Walters-Conte, Zeller, 2015). One small 20 by 20 transect on the American University campus can be observed, and experimented on, in order to demonstrate the incredible diversity of life. If this is done, then it will be possible to observe the interrelation and complexity of species in several different niches within the same transect.

Materials and Methods

A triangular piece of land with 20-meter long sides was marked off. This land establishes the experimental transect (transect #5). The general characteristics of the transect were carefully observed and marked down in order to form a topographical map. Both biotic and abiotic components of the transect were carefully recorded. After thoroughly observing the transect, a sample of the soil and vegetation that was representative of the transect was collected in a 50 mL conical tube. This sample was then used to make a Hay Infusion Culture. This was done by removing 12 grams of the soil sample and adding it to a plastic jar. 500 mLs of deerpark water was then added to the jar, followed by 0.1 gm dried milk. With the lid placed on the jar, the solution was gently mixed. The top was then removed, and the jar was left to sit for one week.

Data and Observations

Transect #5 is situated in the “manicured grass” of the American University Eric Friedheim Quadrangle. The grass which dominates most of the transect is cut short, and clearly maintained. There are small patches of dirt and snow visible throughout the transect, and fallen leaves and acorns are scattered across the grass. There is also 2 pieces of visible trash on the grass, a straw and a fork. Along one side of the transect there is a slightly elevated, and clearly landscaped, mulch area. This mulch, which also has patches of dirt and snow, contains both deliberately planted (landscaped) and wild-growing plants. The landscaped plants include bushes with sharp thorns, which possibly resemble beach roses. There is also a different unidentified landscaped plant. There are several varieties of wild-growing plants, or weeds, as well, including dandelions, crabgrass/wild grass, and clover.

As the transect is an ecosystem, both biotic (living) and abiotic (nonliving) components present.

Biotic: Bushes with thorns (beach rose bushes?) Grass Berries Weeds (clover, dandelion, crabgrass) Worm Other landscaped plants

Abitoic: Snow Dirt Mulch Rocks Trash (straw, plastic fork)

After making detailed observations, an aerial-view topographical map of the transect was drawn. The red line represents the border of the transect.

Conclusions and Future Directions

A quick overview of the transect would probably lead to the conclusion that it is mainly grass, with some landscaped plants. However, by more closely observing the transect, it was possible to see a bit more of the diversity. It revealed that there were actually two separate kinds of landscaped plants, as well as some naturally growing weeds that were almost hidden by the beach rose bushes. It also revealed that there was mulch and partially melted snow mixed in with the dirt and grass. There were also pieces of trash hidden among the grass. This demonstrated how an ecosystem does in fact have both biotic and abiotic components. The complexity of the kinds of organisms within the transect was revealed through the closer observation. However, not all species of organisms were visible to the naked eye. In fact, about 1 teaspoon of soil can contain billions of microbes including unicellular eukaryotes and bacteria (Freeman, Allison, Quillin, 2008). By setting up the Hay Infusion Culture and letting it sit it will be possible to observe microscopic protists, algae, bacteria, and more, in the coming weeks.

References

Bentley, M., Walters-Conte, K., Zeller, N. 2015. A Laboratory Manual to Accompany General Biology II. American University Department of Biology: Washington, DC. 16. Freeman, S., Allison, L., & Quillin, K. 2014. Biological science (5th ed.). Pearson: Glenview, IL. 531, 1174-1175.

-SM

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