Perfect Paragraph

Ommochrome pigments are a type of pigment that is present in a large variety of arthropods. The pigment is present in both the eye and the body of the arthropod. The current hypothesis is that the color of the pigment is important to the pathway for color changing insects. Crab-spiders are unusual due to their ability to have reversible color changes. They are able to go from white to yellow and back to white again. The color change in the crab-spiders was originally attributed to the carotenoid pigment (commonly produced by plants which provides the yellow/orange coloration) but the pigments responsible for the spider’s color change was later found to be ommochromes. The color mimetism that the spiders are able to replicate is able to fool the discrimination ability of bees. Bees and other flowering visiting insects are known prey to the spiders and due to the close match between spider and flower, it is suggested that the color change is a predatory adaptation. Data and research is still being gathered and conducted between the spiders and birds to test if the color change may also be the result of a defensive mechanism.

 

Observation of a colony from the pasteurized plate, under a phase contrast microscope at 1000x, showed endospores inside rod shaped bacterium. The endospores were located primarily at the terminal end of the bacillus, and were seen as bright ovals with the darker bacterium surrounding them. This confirmed that the bacillus containing endospores survived pasteurization and was able to continue growing on the nutrient agar. Not all of the bacilli contained endospores, suggesting that the nutrients on the agar were substantial enough to inhibit sporulation. These bacilli grew in diplobacillus and streptobacillus arrangements. A Gram stain of the same colony used for microscopy showed that the endospore forming bacilli were gram positive based on the dark purple color of the bacterium. The endospores were not stained and appeared as clear ovals at the terminal ends of the bacterium. This Gram stain confirmed that the bacterium that formed the endospores were Gram positive. Also, the Gram stain showed that the thick layer of proteins and peptidoglycan surrounding the endospore had not been damaged and was able to keep the stain and water out of the endospore.

The cytoskeleton has diverse functions, owing to the diverse structure of the proteins and filaments that form it. The interactions between these proteins result in emergent properties that add yet another layer to these diverse functions. Two major proteins in the cytoskeleton are actin and tubulin, which comprise microtubules and microfilaments respectively. Actin and tubulin have different structures and functions, and interact with each other to create emergent properties. One characteristic that is extremely different in tubulin and actin is their stiffness; microtubules made of tubulin are much more stiff than microfilaments made of actin. When these two proteins are added together in high concentrations, they interact sterically, and as a result, conform to the “reptation” or “tube” model. Each filament is spatially restricted to a tube-like area, which is formed by the constraining filaments around it. In order to relax and decrease the straining forces on it, the filament reptates, (sliding curvilinearly) out of its tubular space. There are other methods by which the filaments can partially relax, such as bending fluctuations.The interactions that occur in cells between actin and tubulin are integral to cellular function. Interactions between these proteins provide controlled, structured support of the cytoskeleton. They also are also important in cytokinesis and cell motility. Another key trait of microtubule-actin interactions is their ability to reinforce each other’s strength and elasticity. When interacting with the supporting actin network around it, a microtubule can withstand much larger forces without buckling than it would be able to withstand alone. Learning the interactions of these filaments has several different potential applications. In material engineering, tweaking the ratio of softer, more flexible rods (such as actin) to stiffer rods (such as tubulin) could help one discover the ideal ratio to be used to synthesize a material that is light yet durable. Combinations of actin and tubulin also provide the possibility for increased control over large-scale mechanics. 

Looking back at my statistics 240 course, I realize that I remember a lot of key concepts but some of the details of calculation are a blur.  For example, I know all of the basic measures including mean, median, mode. I recall that significance in a set of data is a way to determine if an effect was actually observed. Also, confidence intervals are essentially a measure of how confident you can be that the obtained result could be repeated. A confidence interval of .9 indicates 90% confidence and .99 indicates 99% confidence. If you have a very large sample and a high confidence interval then you can more readily rely on the validity of the results. In addition, a given sample size must have a minimum of thirty participants for its results to be considered significant (n=30). All of these concepts can be related to the normal distribution. When conducting an experiment, you want to prove that your hypothesis actually generated a result. By using statistical analysis, you can provide a numeric confirmation that a difference was observed between an original condition and the experimental condition. Since it has been awhile since I took the course, I’m not currently confident with all of the calculations pertaining to these concepts. Luckily, these are things that I could open up my old notebook and refresh myself on.

 

Regarding the Emlen funnel tests, 40.9% were discarded for being either inactive (7.4%) or disoriented (33.5%). There is no further information about which birds had their tests discarded, which could be an interesting fact to consider because it could change sample sizes and induce bias. In order to support the discarding of such tests, the researchers could refer to the variables that may have influenced the results, such as the weather or the age of the bird. It is possible that some of the discarded results belonged to juvenile birds on their first migration, which would use vector navigation since they still lack part of the map component of navigation that is gained through experience. Since birds may rely on multiple cues for navigation, this study does not provide the whole picture of bird migration because it was performed at fixed locations. An interesting follow-up study could track the same birds with satellite tagging to determine if they reached their breeding grounds despite having a sectioned V-1.

The cross bridge cycle is responsible for the contraction of muscles. A muslce is made up of myosin and actin. Actin is the thin filament and myosin is the thick filament. The muscle recieves a stimulus from a nerve cell that results in the release of calcium from an internal storage within the muscle. The increase of calcium concentration within the microfibules is what allows the cross bridge cycle to take place. The cross bridges cannot form without calcium because calcium is what allows the active sites to become exposed and without exposed acctive sites, the bridges cannot form. Calcium binds to troponin and as a result troponin changes it's shape. This shape change alters the positioning of the tropomyosin which exposes the active sites. The cross birdges then form. In the presence of calcium, the myosin binds to the actin. The next step is the powerstroke which is when the myosin head pivots, pulling the actin to the center of the sarcomere. ADP is released in this step. In the next step, ATP binds which triggers detachment. The cross bridge detaches as a result of atp hydrolysis. During the last step, ATP hydrolysis the myosin head is coked. The use of energy from ATP to ADP is used to rebind. This is one full cylce of the cross bridge cycle. 

There are two factors that are necessary in cross bridge formation; elevated calcium concentrations and ATP. Elevated concentration of calcium concentration is a requirement because cross bridges cannot form without calcium changing the shape of troponin. An adequate supply of ATP is also necessary because this process requires energy. 

In the crossing of the mutant strands, there were fewer colonies observed than was expected on the control plate (one-hundred and fifty). This might have been due to a dilution error. For the MV plates, there were approximately ninety colonies observed. The reason for this proportion colonies may be due to not plating the same number of cells on the control plate as there should have been. Theoretically, there should have had a 20% survival rate if the optimal exposure was achieved. For the MV plate, the survival rate was 3.3%. This is significantly lower than expected and might be due to errors as mentioned above. There were no mutant phenotypically red colonies observed. This was expected, as you need about 10,000 surviving yeast cells for each mating type (3) to observe surviving mutant colonies that express a red color. The survival rate for our control plate was 6%. This was also much lower than the 20% expected survival rate, for reasons similar to the first plate. 

Yesterday there was a lot of buzzed in the internet of how five patients had gone through a stem cell transplants and showed no signs of HIV. Does this mean that the virus is not in their body anymore? Can there be a cure after all? According, to the scientific journal “Annals of Internal Medicine”, this is a great start of research that wants to determine associated factors with stem cells transplant that could help the elimination of HVI. This study was based on the peculiar case of Timothy Brown, known as the Berlin patient. He was diagnosed in 1995 with HIV, he had a stem cell transplant to treat his leukemia. His donor had a CCR5- delta 32 mutation, that makes the blood cells to be immune to HVI. And so, Brown became resistant to the virus and is considered to be the only person in the world that has been cured from HIV. In order to discover this type of transplant and other factors, the people that were in charge of conducting the study, asked six volunteers with HIV that also had gone through stem cells transplant to be part of the research. After the analysis, monitoring and antiretroviral treatment, it was observed that five of them had undetectable levels of HIV in the blood and tissues. Also, one of the participants antibodies that was present to protect the virus had disappeared completely after six years after the transplant. This could only mean one thing, HIV was not present in his blood. Despite the promising results, we cannot talk about a cure yet. However, this discovery represents a great advance in new strategies to fight against and eradicate this virus.

One of the most important aspects of the science community is the ability to replicate processes and get the same results. In order to be able to achieve this goal, clear and concise writing is required. In Fall 2018 the Writing in Biology Class at the University of Massachusetts Amherst, conducted a project to observe differences between two figures. Figure 1 was to be created by me and Figure 2 was to be created by another student following my methods section to try to create a perfect replicate of the Figure I already created. The following section focuses on the subject of the figure, including why it was selected, and the factors that were attempted to be controlled in the writing of the methods section

Mammals, often characterized by the presence pf hair and mammary glands, can be divided into three sub groups; Holotherians, Metatherians, and Eutherians. Holotherians encapsulate the monotremes which are the egg laying mammals characterized by a single opening for both fecal removal and urogenital products. Examples of monotremes are platypuses and echidnas.  Metatherians are the marsupials like kangaroos, wombats, opossums, etc. They are characterized by a pouch where the fetuses attach to the mother’s nipples and finish developing into adolescence. Metatherians also have an inwardly turned angular process on their lower jaws which result in limited replacement of their juvenile teeth. Lastly, Eutherians are the remaining placental organisms. While marsupials are placentals too, Eutherians have a longer gestation period and thus produce able bodied young who are at a much more advanced stage in development. Eutherians are also characterized by their tribosphenic molars, molars where the protocone is on the lingual side of the mouth (tongue) and the anterior paracone along with the posterior metacone are on buccal side of the jaw (cheek). In conclusion, while mammals are united by their hairs and mammary glands, they can be further divided using distinct characteristics that allow us the create the three groups Holotherians, Metatherians, and Eutherians.