The aim of this experiment was to use wild type and mutant strains of Chromobacterium violaceum to explore N-acyl-homoserine lactone (AHL) based quorum sensing in Gram negative bacteria. AHLs are signal molecules produced by Gram negative rods. They regulate antibiotic synthesis, expression of virulence genes, biofilm formation, and several other cellular activities. Two genes are responsible for AHL mediated gene regulation. One encodes a transcriptional regulatory protein (R gene), and the other encodes the enzyme AHL synthase (I gene). The presence and proper functioning of these two genes is essential for the target genes to be transcribed. AHL synthase produces AHL molecules, which are classified by their side chain length and molecular structure. AHL synthases differ between each genus of bacteria, and produce AHL molecules that are slightly different from each other. Most regulator proteins that bind AHL molecules are specific for a certain AHL structure, but some can bind more than one type of AHL. This can create the phenomenon of cross-communication between different species of bacteria. This experiment was done to explore quorum sensing in Gram negative bacteria and determine if different species of bacteria could communicate with C. violaceum.
A-site: the ribosomal site most frequently occupied by aminoacyl-tRNA. The aminoacyl-tRNA in the A-site functions as the acceptor for the growing protein during peptide bond formation.P-site: the ribosomal site most frequently occupied by peptidyl-tRNA, i.e. the tRNA carrying the growing peptide chain. The P-site is also referred to as the puromycin-sensitive site. Puromycin is an antibiotic which shows similarities with a part of aminoacyl-tRNA. When puromycin is present in the A-site, the peptide can be linked to puromycin via a peptide bond. Thus, peptidyl-tRNA in the P-site is located in the puromycin-sensitive site. E-site: the ribosomal site harboring deacylated tRNA on transit out from the ribosome.
The aim of this experiment was to explore the wide variety of organisms found in biofilms that form on toothbrushes. My lab partner’s used toothbrush was the source of these bacteria, and was sacrificed for the purposes of this experiment. The toothbrush head was cut off and placed into sterile saline to create a fluid suspension. An inoculum from the toothbrush-saline suspension was streaked onto TSA, SBA, MacConkey agar (MAC), Mitis-Salivarius agar, and CDC anaerobe blood agar plates. After incubating the plates, it was expected that each one would contain several different colonies that would allow the bacteria growing on the toothbrush to be directly observed.
The results of this experiment were in accordance with my expected results. On the slide culture of P. aeruginosa, a thick, slimy, green goo had grown and covered the entire slide and surrounding glass dish. When I attempted to remove the glass slide from the dish, long thick strands of biofilm formed between the slide and the glass dish. It was like when you take a bite of cheese pizza and the cheese forms a long, gooey strand between your mouth and the slice. When I put the P. aeruginosa slide under the microscope at 400x, I could see long, thin, greenish grey strands of biofilm going in all different directions. It was clear from this slide that P. aeruginosa formed a biofilm that contained lots of EPS. At 1000x the strands were not as defined, but rod shaped bacteria with thin EPS and biofilm filaments in the extracellular space were clearly visible. This showed that P. aeruginosa is an excellent biofilm former, and can form biofilms in an artificial environment in the lab.
The aim of this experiment was to observe biofilms microscopically by growing them on a slide using a process called slide culture. Using a technique called flow through Gram stain, the biofilms on the slides were kept wet to maintain their complex arrangement. Keeping biofilms wet is essential to preserving their structure, and allows them to be seen under a microscope. The inoculum for these slide cultures was obtained from two different sources. The first slide culture sample was taken from a pure culture of Pseudomonas aeruginosa. This Gram negative, rod shaped bacteria is an excellent at forming biofilms, which contribute to its virulence in humans and animals. It was expected that P. aeruginosa would produce a thick, slimy, dense biofilm on the slide culture. It was also expected that extracellular polymer substance (EPS) would be able to be seen under the microscope.
After the extraction, the product yield was 0.622 g which was a 59.35% yield from the mass of the nutmeg that used. The extraction is the first step to isolating the trimyristin from nutmeg and the product from the extraction was recrystallized to purify it. The percent yield after the first recrystallization was 25.08%. The melting point for this product was between 54 and 56 °C. The literature gives a melting point range of 56-57 °C for trimyristin. The range matches closely and the crude product upper limit is the same as the given lower limit for trimyristin. The first recrystallization product can therefore be confirmed to be trimyristin and the slightly lower level in melting point suggests it is not yet a pure sample. After the recrystallization, a melting point between 55-56 °C is achieved for the product. Some of the material was used for the hydrolysis, but what was used to recrystallize gave a 72.91% yield. The melting point range decreased by 1 °C and moved closer to the literature range for trimyristin. As the second recrystallization was of the crude trimyristin product of the first recrystallization, not changes should have occurred, and the product can be identified as trimyristin. The 0.062 g taken from the first recrystallized product was used in the hydrolysis and acid addition part of the experiment and gave a product that after drying weighed 0.049 g which gave a 79.03% yield in product. The dried sample also had the melting point taken and was recorded at 54 °C. The literature gives a melting point value of 54.4 °C for myristic acid, so the product of hydrolysis and acid addition can be identified as such.
The findings of this study will be very beneficial for multiple reasons. The data we collect will give us insight into the behavior and lives of the small cellar spiders that live in basements and homes right alongside humans. Not much is known about the effects of LEDS on spiders and specifically on creating a web in the presence of LEDs. Today and going forward, LED lights are the new light bulb, they are more efficient, cheaper, easier to install and use, etc.. This means that the LED light will began to have a much larger presence in the outdoors as street lamps, lights in the park, etc.. With LEDs becoming more and more prominent and mixed into our surroundings, this study will show some of the effects LED lights can have on spiders creating their webs, eating, sleeping, and just their overall behavior. This study, in part with others, can then be used to decide where to put LEDs up, how intense to have them, and the schedule for the LEDs. This study could also bring insight into the most effective ways to repel spiders from living and coming into houses and other places.
Biome 2 doesn’t have a direct match to an earth biome however it does follow a similar seasonal pattern to a tropical rainforest. Rainforests have little seasonal variation and therefore have pretty consistent precipitation and temperature patterns throughout the year. Because the data on biome 2 shows little seasonal variation it can be expected that this biome is located near the equator. The closer to the equator you get, the less of an effect the axis has on climate, so there is little variation. I would predict this biome to be equatorial because of the lack of seasonal variation. I would not consider it to be a tropical rainforest however because it has much less average precipitation and a much lower average temperature. The lack of precipitation would not allow for the abundance of species found in a rainforest. You might expect to see similar plants, as in ones that are not acclimated to seasonal change. They would not lose their leaves in the winter. You would expect to see a lot of vegetation year round because their is still substantial rainfall and there is never a period of freezing temperatures that would prevent the growth of many plants.
Biome 1 is most similar to a temperate deciduous forest based on both temperature and precipitation. Temperate deciduous forests vary seasonally in terms of both temperature and precipitation. The winters are typically cold and dry and the summers are warmer and typically see more rainfall. The peak of both precipitation and temperature occurs some point in time over the summer. The graph for biome 1 shows seasonal variation, with the winters having below freezing temperatures and the summers ranging in temperatures between 20-30 degrees celsius. The biome on this new planet has slightly warmer summers than this earth biome but follows a similar pattern. This biome also has more rainfall on average than earth but again, has a similar seasonal pattern. You would expect this biome to be located around 30-50 degrees latitude. On earth, this type of biome is found mostly in the northern hemisphere because the southern hemisphere lacks the landmass needed, however, since we don’t know of any land differences between the northern and southern hemisphere of this planet, it can be expected in both hemispheres. You would also expect to find plants with deciduous leaves, so they loose their leaves in the sub freezing winters. Because there is such variety seasonally, the plants would likely be well adapted to seasonal change. On earth, you find maple, birch and many other types of trees so you might find similar trees in this new biome. There is more rainfall as well so it might be expected to contain larger trees.
To determine the relationship between spider weight and spider web thickness, 3 different species of spiders of different sizes will be collected from various sites around campus. We will collect 2 spiders in each species. The spiders will be weighed on analytical scales and will be sorted based on weight. They will then be placed in separate containers and will be allowed to spin out spider silk.The spiders will be left in their containers to make a web for 5 days. We will feed them 1 fruit fly each day. We will remove the web with tweezers and place onto a microscope slide. The silk will be fixed onto microscope slides using distilled water as a buffer. The silk will be observed under a microscope at 40x magnification and be characterized based on size, using a stage micrometer, and web type. The webs will be sorted based on type, and then subgroups will be made based on size. The data will be analyzed based on the spider species and then the web size will be compared to spider weight to determine if any correlation exists.