Writing in Biology - Section 1

Plants require light energy and water to produce energy-rich compounds which can later be used to fuel sugar making mechanisms. In order to first capture light energy, a plant will use chlorophylls a and b in a chloroplast. These kinds of chlorophylls absorb red and blue light, therefore reflect green light waves and appear green to us. The electrons are captured in photosystem 2 and transferred to photosystem 1 and eventually to the NADP reductase where they are used to add a Hydrogen to it and make NADPH. Water is broken down in photosystem 2, removing the hydrogen and producing free hydrogen and a diatomic oxygen molecule. The hydrogen goes into the thylakoid lumen of a chloroplast to create a high gradient that is then used to drive ATP synthase to make ADP into ATP. 

In any given ecological community where multiple species use the same resource, there is bound to be competition. Competition between two species will always hinder both populations as long as both are present because the maximum capacity of the environment can only hold so many individuals. Studying these sorts of interactions allows scientists to understand how two species interact and how stable their interaction is. In order to quantify the competition of two species, scientists use the Lotka-Volterra equation. This equation takes into account the populations of both species, the effect of one on the other, and the total carrying capacity to produce a value indicating how the target population will grow. A graph can be plotted using the zero growth isoclines for each species; the number of individuals that could be sustained given only 1 species is present. Interpreting the graph will grant the best understanding of how these populations are interacting. If the species populations seem to converge at 1 point in the graph then there is said to be a stable equilibrium. An unstable equilibrium happens when there are 'risk' zones and if the number of individuals falls within these zones it is likely one population will push the other to extinction.

There are four primary methods used in biology to produce transgenic organisms: transgene engineering, knock-in engineering using embryonic stem (ES) cells, knock-in engineering using CRISPR, and viral gene delivery. Here, I will go over the first two of these methods. Transgene engineering was the first time foreign genetic material was incorporated into an animal’s genome. Palmiter and Brinster added the gene for human growth hormone (HGH) to zygotic cells during the stage at which the genomes of each parent cell are fusing in order to get random incorporation of the gene. In order to get expression of this gene they also packaged a promoter with the transgene which would ensure its expression in transformed mice. The next step in genetic engineering came with knock-in engineering in ES cells developed by Capecchi, Martin, and Smithies. This method involves using a new kind of transgene that lacks a promoter but has gained a neomycin resistance gene and homologous arms. A promoter is unnecessary as the arms of homology will target the transgene to a specific place in the genome after a promoter that is already active. The transgenes are then added to cultured ES cells. The cells that take up the transgene and undergo a double-stranded (DS) break that matches the transgene’s arms of homology get transformed. Then, the antibiotic neomycin is added to the cultured cells to select for the cells that were transformed. These transformed cells are injected into a blastocyst where they can be expressed.

Located on an island in the south Aegean sea, an ancient civilization known as the Minoans ruled for over 600 years. Archaeologists know of this great civilization in part due to Sir Arthur Evans, a very rich man who was determined to discover who these people were. At some point in his life, Evans came across some seal stones which depicted bulls and mythological creatures with origins supposedly on the island of Crete. Not much else was known at the time, and because of that Evans became inspired to pursue his curiosity. Excavations went underway, lead by specialists Evans hired, and quickly they began to uncover the secrets of Crete. Being the eccentric person Evans was, he took it upon himself to reconstruct many of the damaged sites he was exhuming based on his interpretations. On Crete, there were great palaces and villas, many adorned with paintings referred to as frescos depicting life in ancient Minoan society such as the sport of bull-leaping and elite women. Explorations uncovered large ceramic jars at the palace of Knossos estimated to collectively house 62,000 gallons of liquids. Evidence of the types of foods grown here suggests these liquids were olive oil and wine collected as taxes from nearby estates. 

In the human body, DNA is stored as chromatin when not being actively transcribed. Chromatin refers to the wrapping of DNA around histone proteins to control tangling, proper spatial storage of DNA, and regulation of gene expression. In order for these histones to open, exposing the DNA to RNA polymerase, transcription factors, and other necessary transcriptional hardware, acetyl-CoA is required. This acetyl CoA is derived from the metabolism of acetate by the enzyme ACSS2. Mews et al. have discovered that, through the consumption of alcohol, a rapid increase in levels of blood acetate occur resulting in rapid acetylation of histones in the brain¹. The findings of this study show that alcohol consumption directly results in changes in gene expression in the brain, including those in neuron cells.

(1) Mews, P., Egervari, G., Nativio, R., Sidoli, S., Donahue, G., Lombroso, S. I., … Berger, S. L. (2019). Alcohol metabolism contributes to brain histone acetylation. Nature. doi: 10.1038/s41586-019-1700-7

Today I wanted to explore how to slow down the growth of he Drophilia flies. They grow and reproduce very rapidly, in even 24 hours you can see an entire reproductive cycle between male and female, of course unlike humans, where it takes a female 9 months to conceive. The Juvenile Hormone Inhibitor slows down the growth and development of the Drosophila flies, in both males and females. This indicates that the JH Inhibitor is correlated to the growth and development of Drosophila flies, although more testing would need to be done in order for this to be fully conclusive. I am also not a professional, nor a qualified scientistm but the Juvenile Hormone is necessary in the instar stages, so by adding an inhibitor, we delay this growth, which explains why the fly count decreases once the inhibitor increases, as well as the size of the fruit fly. More precisely, Juvenile Hormone supports the instar stages, which is the stage between the eggs and the pupa stage. Once the eggs hatch, there will be a decrease in the quantity of larvae that wil later on develop into pupae. This also effects their length. This shows how the Juvenile Hormone was able to delay and disrupt the developmental stages of fruit flies. 

In dogs, coat colors are controlled by many variations in gene expressions and alleles. In a simplified analysis of these changes, three main genes produce obvious and predictable traits in dog phenotypes for coat colors and patterns. The TYPR1, MC1R, MSH, and ASIP genes all have complex involvment in the pathways to produce color and pattern of color in dogs. The MC1R allele codes for a receptor protein on the membrane of melanocyte cells, which are cells that are responsible for the expression of the color genes in dogs, and therefore control the color pigments produced in the hair follicles. When this allele is precent in the genome in the wildtype, the receptor protein interacts with all the molecules it is meant to and successfully passes the message from the extracellular matrix. Once received the signal causes the transcription of the TYPR1 gene which produces the pigments required to make black colors. If TYPR1 is the only mutated gene and is homozygous recessive (AARRbb) then the color will be brown. ASIP genes code for a molecule that also get received by the MCIR receptor. If ASIP is the only signaling molecule present, the pigment becomes red by a different mechanism. MSH is the other molecule (in the simplified model) that is recepted by MC1R, and if this molecule is present it is dominant in reception to ASIP, and the transcription for black/brown color does occur. If MC1R is mutated (rr) then there is no transcription of the pigment genes and the hair will lack color and appear yellow or white. However, MC1R is only vital for HAIR pigmentation, therefore other parts of the dog will be colored black if the B gene is present even if the R gene is not present, giving the possibility for a yellow dog with black nose. A brown dog cannot have a black nose because the hair color determined that the black gene was already missing in the dog, and the receptor is wildtype. 

Changing the phenology of flowering times in cranberries not only affects cultivators but it also affects species that closely interact with the cranberries. Lycaena epixanthe, bog copper butterflies, are affected by earlier flowering times of cranberries. Adult bog copper butterflies consume flower nectar while the developing caterpillars consume shoots and leaves. Two major issues occur when the phenology of the cranberry changes. First, the phenology of the bog copper butterfly may not match up with its food source the cranberry. Second, if the cranberry flowers earlier and cultivators spray herbicide earlier, then the bog copper butterflies may come after the cultivators have sprayed rather than before. Cultivators may find it easier to yield a crop that is not consumed by the bog copper butterfly caterpillars, however, they still need the butterfly as a pollinator for the crop. This process has been studied with bees as pollinators (Bartomeus et al.). Understanding this process is important as it may clarify the process of earlier flowering times and pollination for both agricultural purposes as well as in the wild.

The flu shot is often neglected, according to the centers for disease control, only 37% of Americans recieved their flu shot in the 2016-2017 season.  The flu shot changes every  year to keep up with the varying proteins on the virus. The vaccine is important for the recipient's protection against the flu, as well as everyone surrounding them. Certain individuals are vulnerable to disease, they are the elderly, infants, those recieving chemo-therapy, and individuals with an autoimmune disease. Individuals who are immunocompromised cannot get vaccines; vaccines should be administed several weeks before the individual becomes immunocompromised (if that is possible, such as several weeks before chemo-therapy). These immunocompromised individuals can be protected through herd immunity; when the majority of a population is vaccinated, the virus has a hard time infecting individuals.  Therefore, everyone should keep up with their flu vaccines to prevent contraction of the virus for themselves, as well as immunocompromised individuals who cannot recieve the vaccine and rely on others for protection.

The effects of temperature on insect activity have been researched across taxa ranging from Diptera (Bowler & Terblanche, 2008) through Coleoptera and Lepidoptera (Briere et al., 1999) to Hymenoptera (Abou-Shaara, 2014). Throughout these orders, insects demonstrate the ability to detect temperature, which can help them perform tasks from determining foraging window timing (Vicens & Bosch, 2000) to finding the warmest location in a stack of wheat (Flinn & Hagstrum, 1998). Understanding the factors that influence insect behaviour is critical to advances in sustainable agriculture practices and conservation management. In this study, we analysed the effect of environmental temperature on the foraging behaviour of the large milkweed bug (Oncopeltus fasciatus). In order to better preserve the Apocynaceae and Asclepiadaceae plant families (here collectively termed "milkweed") that are integral to the survival of many species including the monarch butterfly (Danaus plexippus) (Flockhart et al., 2014) it is important to understand the foraging behaviour of the milkweed plant’s primary predators.