User:Ariel Michelle Drew/Notebook/Biology 210 at AU

1/28/15 I figured it out

Observing a Niche at AU: Wildlife Preserve 1/14/15 • This procedure is attempting to examine the various forms of organisms across the American University campus. Organisms are dependent on the environment and thus certain Niches will be more favorable for particular organisms. I must assert that if the Wildlife Preserve Niche contains quite a bit of disrupting factors, as well as favorable ones (lots of direct sunlight, and precipitation) then there will be a median amount of diversity within the the medium sized population of organisms. • This procedure required paper and pencil for observation, and a 50 mL plastic container as well as abiotic and biotic factors (listed below) of the Niche for sample collection. The sample was kept at room temperature after the Hay Infusion (requiring 11 grams of vegetative sample, 500 mLs of deer-park water, 0.1 gm dried milk—mixed together for 10 seconds) was completed. Then the jar was labeled and the top was removed. Next, the open jar was placed near a window. • Niche appears to get copious amounts of light and precipitation. Niche is thick with biotic features such as trees (one containing red berries, the other with no leaves), moss, grass, bushes, and a taller more distinctive form of grass. Niche is considerable polluted with litter, but also contains more favorable biotic factors such as rocks, benches, dirt, and mulch (distinctive from the dirt observed). It is also important to note that the Niche appears to be unprotected from wind, and contains quite a bit of foot traffic. • I predict that Niches in direct sunlight, and that contain large amounts of precipitation, and relatively few disrupting factors (such as wind and foot traffic) will have more copious and diverse forms of life. Considering the forceful wind observed as well as the large amount of litter noticed in the Niche, it could then be concluded that this Niche contains quite a bit of disrupting factors, thus inhibiting a larger organism population. I am not yet certain whether this will affect the diversity in organisms observed. Next time I may want to harvest soil samples from 5 inches below the surface as well as the surface to test if the foot traffic affects organism population and diversity.

Hay Infusion Culture Observations and Preparing and Plating Serial Dilutions 1/21/15 • The purpose of this experiment was to establish what types of microorganisms live in a particular niche (in this case the wildlife preserve niche) and possibly determine a carrying capacity (the maximum number of individuals of a species that can survive in a particular niche), and prepare the organism samples for lab next week. If our niche contains plentiful microbiotic specimens then I assert that they will be rather singular in structure. • The Hay Infusion Culture Observations procedure required a pipet to extract samples from the Hay Infusion (kept at room temperature) and a slide to put those samples on. A microscope was used to observe the organisms, while a dichotomous key is used to identify. The Preparing and Plating Serial Dilutions procedure required four tubes of 10 mLs sterile broth labeled with 10^-2, 10^-4, 10^-6, 10^-8. A micropippetor set at 100 microliters with tips was also needed. Four nutrient agar and four nutrient agar plus tetracycline plates were obtained. Plates from each of the two groups were labled 10^-3, 10^-5, 10^-7, 10^-9. 100 microliters from the Hay Infusion culture was added to the 10 mLs of broth in the tube labeled 10^-2 and mixed thoroughly, making it a 1:100 dilution. 100 microliters of broth from tube 10^-2 is added to tube 10^-4 and mixed thoroughly (making a dilution of 1:10,000). This process is repeated two more times to make the 10^-6 and 10^-8 dilutions. To plate serial dilutions on the nutrient agar plates, pipette 100 microliters from the 10^-2 tube onto the nutrient agar plate 10^-3. This procedure is repeated with the 10^-4 dilution onto the 10^-5 plates, the 10^-6 dilution onto the 10^-7 plates and the 10^-8 dilution onto the 10^-9 plates. Agar plates are then placed side up in a rack where they will incubate at room temperature for one week. • Smell: Earthy, stale, swampy. Appearance: No apparent life on top. Coated in a goopy, crusted grey-purple slime on top. Organisms in Top Sample: Colpidium (motile via cilia) (about 50-70 micrometers long) (protozoa because it is a motile, unicellular, eukaryotic organism). Paramecium Caudatum (motile via cilia) (about 200-300 micrometers long) (protozoa because it is motile, unicellular eukaryote). Volvox (motile via flagella) (about 200 micrometers in diameter) (Type of Green Algae). Organisms in Bottom Sample: Colpidium (no other organisms were noted, despite the observation of several samples from the bottom of the culture). No photosynthesizing organisms were noted. • The Volvox organism obtains energy through conversion to ATP by way of photosynthesis. The Volvox forms a colony of up to 50,000 cells. The individual Volvox cells are connected to each other by thin strands of cytoplasm, this allows the colony to swim as a coordinated unit. Each colony is formed with an exterior ball of swimming cells, and an interior ball of reproducing cells. In this colony of 50,000 cells, there is no nervous system. Swimming thus cannot be conducted by way of electrochemical nervous system signals, so most likely swimming is achieved by crowd-sourced behavior. Volvox is a form of algae, and this type of algae is attracted to light so that photosynthesis may be achieved, and thus this crowd-sourced movement will be drawn towards light. Volvox is a asexual organism, containing both somatic cells (which do not reproduce) and gonidia near the posterior, which produce new colonies through repeated division. Ancestors of Volvox transitioned from single cells to multicellular colonies at least 200 million years ago, with this transitory period lasting approximately 35 million years. • If the Hay Infusion Culture “grew” for another two months, I would expect the amount of protists and algae to have significantly increased. I would assume that amount of sunlight available would be a significant selective pressure on the community of the sample. It would also be reasonable to assume that certain portions of the Culture will receive more sunlight than others, and depending on whether organisms are motile or not, whether they can reach these better lit sections of the Culture.

Nutrient Solution Plates: Agar Positive Plates: Agar Negative 10^-2 10^-3 10^-3 10^-4 10^-5 10^-5 10^-6 10^-7 10^-7 10^-8 10^-9 10^-9

• Our samples seemed relatively lifeless, and found organisms were rather similar in structure. While our niche did not appear to support a plethora of organisms, I was correct in assuming there would be relatively little diversity among the organisms found. Perhaps this lack of life, and singularity is a result of sampling error. If I were to redo the experiment I would collect samples for the hay infusion culture that were about half a foot below the surface to ensure an untainted sample from the plethora of foot traffic and trash present. I would also study more slides of the Hay Infusion culture to test whether life varies based on where the sample is taken from (top, or bottom) (left or right) (middle). I would also like to test whether temperature has any affect on the types of organisms collected.

References Used

Bentley, Meg; Walters-Conte, Kathryn; Zeller, Nancy. 2015. A Laboratory Manual to Accompany: General Biology 210. Department of Biology, American University. American University; Washington DC. 12-24.

Wim, van Egmond. "Volvox, One of the Seven Wonders of the Micro World." Microscopy UK. December 2003. Micscape Magazine. 1/19/15.

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