asalamon's blog

In cancer studies, the changes of gene expression is what is concerning to scientists.  As a result, RNA is necessary to study changes in gene expression.  RNA is an extremly unstable molecule and it needs to be to ensure regulations of gene expression.  In order to study RNA effienctly, reverese transcription is used via reverse transcripase to create cDNA from the RNA template.  When the RNA is being studied, the introns have already been spliced out allowing for a precise understanding of the exact DNA sequence causing the regulation without introns interferring with it.  PCR can then be used to replicate the cDNA and allow for several copies of DNA to be used.  In PCR, there a phase where the reaction platues.  Therefore, there needs to be flourences and a window to see the levels of all the DNA to determine which sequences are amplyfying fastest.  Before the platue, the levels can be compared to see what gene is expressed most in the cancer cells.

PCR, polymerase chain reation, is used to create replications of DNA in the lab.  Temperatures of a bath are raised and cooled to ge the double strands to separate, primers to be inserted and tac polymerase will extend the stand.  The process is left with short stands of target sequences which have been replicated as they were defined by primers.  This started as a labor intensive process which required hours of manual labor and a large quanitites of enzymes until a bath was invented which allowed for the thermoregulation of the temperature.  

Due to the increased use of capsaicinoid and tolerance of capsicums in the human diet, other health benefits emerged as a consequence.  In Tsuchiya’s study of the effects of capsaicinoids on membrane fluidity, bacterial growth and platelet aggregation were the two subjects (2001).  The lipid form of capsaicinoids were able to interact with the membrane in bacterial cells, inhibiting their growth (Tsuchiya, 2001). This effect on bacteria could result in capsaicinoids being essential in maintaining a healthy gut biome for an individual who was raised in an environment with a high spicy food tolerance.  Gastrointestinal disease has been reported to be decreased with capsaicin consumption (Deng et. al., 2016). In platelets of humans, rabbits, and rats, capsaicinoids were shown to decrease their aggregation (Truchiya, 2001). Capsaicin has already been proven in other studies to decrease cardiovascular disease (Deng et. al., 2016).  The effects of membrane fluidity could be one of the physiological changes within the body which decreased cardiovascular disease. In China, a study was conducted to determine if chili intake and capsaicin had any effect on the obesity of the population (Shi, Riley, Taylor, & Page, 2017). Although this was one of the first conclusive studies done involving obesity, there was conclusive evidence that chili intake had an inverse effect on obesity and might provide a low cost solution to obesity problems in China (Shi, Riley, Taylor, & Page, 2017).  Through the decrease of obesity, there is a multitude of other health complications that can be relieved. One of the flaws with the studies on the health benefits of capsaicinoid consumption is the lack of physiological understanding within the body of how it alters the health of the individual. Until these pathways are fully understood, there will be a slew of health benefits that are not maximized.   

In the study, the limited sample size decreases the accuracy of the study.  Based on the information given, Ulmus americana are the most susceptible to leaf miner infection and have the greatest chance of the leaf miner surviving within the leaf.   From the phylogeny of Ulmus, it is expected that Ulmus americana would have the greatest deviation from the other two species.  While the Ulmus parvifolia and Ulmus carpinifolia had a varying leaf miner presence, they had a relatively similar crude death rate indicating a similarity between the trees which could be explained by their phylogenetic relationship.

Ulmus or elm species and leaf miners.  Leaf miners are relatively harmless to trees but they can have an esthetic effect on trees if they are part of the landscape.  We selected three elm tree where vary along the phylogenetic tree of Elms, the Japanese, smooth and American, with the American being the outlier.  From there two trees from each species had 25 leaves collected from it and the number of leaf mines were counted as well as the number of aborted leaf mines, meaning the leaf miner died.  For our results, we looked at the total number of leaf mines as well as the proportion of those were aborted, the average leaf mine per leaf of each species and the crude death rate per a 1,000 population.  These results showed the highest rate of infestation in the American.  There were similarities in the data of Smooth and Japanese Elm.  Our sample size was very small to have a meaningful statistical analysis done therefore any results of the lab cannot fully support any theory but there are indications that phylogeny can affect the infestation of leaf miners in Elm species as well the their probability of aborting.  For future studies, we would like to expand the sample size of leaves collected as well see if the mortality of leaf miners is seasonal. 

For all these health benefits to be seen, capsaicin has to be regular component of the individuals diet.  Capsaicin tolerance, similar to lactose tolerance, is a trait which evolved over time and some bodies are better adapted than others.  In a study performed with participants suffering from irritable bowel syndrome, the participants with IBS experienced hypersensitivity to capsaicin resulting in an irritated rectum and diarrhea (Gonlachanvit, Mahayosnond, & Kullavanijaya, 2009).  For those whose body is not adapted to handle spicy foods, it is not an advantage for them to consume spicy foods. In Billing and Sherman’s study, there was not as much stress for spices, like capsicum, in diets with cooler average temperatures (1998).  For the individuals who experience IBS which is further irritated by spicy foods, there is an assortment of factors which could have led to this. First, the individual’s ancestors evolved in an environment, like Norway, which led to less pressure for the tolerance of spicy food.  As a result, the mismatch between the environment of evolutionary adaptiveness and novel environment would result in the deleterious results (Nesse, 2008). Since food preference is also affected by environmental and cultural factors, if the individual was not exposed to spicy foods throughout their life, the sudden introduction might be a shock to the individual due to mismatch. 

As well as spicy food tolerance being due to mismatch, it could also be due to the co-evolution with pathogens.  In nature, capsaicin is naturally occuring and could be utilized by humans to fight off pathogens.  Because pathogens evolve at a faster rate than humans, their infections are harder to fight off (Nesse, 2008).  With humans utilizing cultural and behavioral adaptations of spice use in combination with genetic tolerance for spicy foods, humans have better chances of fighting off a pathogen.  In addition, the use of multiple spices in food preparation ensures the maximum lethality of pathogens, reducing their chances of being a recurrent pathogen.     

Due to the increased use of capsaicinoid and tolerance of capsicums in the human diet, other health benefits emerged as a consequence.  In Tsuchiya’s study of the effects of capsaicinoids on membrane fluidity, bacterial growth and platelet aggregation were the two subjects (2001).  The lipid form of capsaicinoids were able to interact with the membrane in bacterial cells, inhibiting their growth (Tsuchiya, 2001). This effect on bacteria could result in capsaicinoids being essential in maintaining a healthy gut biome for an individual who was raised in an environment with a high spicy food tolerance.  Gastrointestinal disease has been reported to be decreased with capsaicin consumption (Deng et. al., 2016). In platelets of humans, rabbits, and rats, capsaicinoids were shown to decrease their aggregation (Truchiya, 2001). Capsaicin has already been proven in other studies to decrease cardiovascular disease (Deng et. al., 2016).  The effects of membrane fluidity could be one of the physiological changes within the body which decreased cardiovascular disease. In China, a study was conducted to determine if chili intake and capsaicin had any effect on the obesity of the population (Shi, Riley, Taylor, & Page, 2017). Although this was one of the first conclusive studies done involving obesity, there was conclusive evidence that chili intake had an inverse effect on obesity and might provide a low cost solution to obesity problems in China (Shi, Riley, Taylor, & Page, 2017).  Through the decrease of obesity, there is a multitude of other health complications that can be relieved. One of the flaws with the studies on the health benefits of capsaicinoid consumption is the lack of physiological understanding within the body of how it alters the health of the individual. Until these pathways are fully understood, there will be a slew of health benefits that are not maximized.   

Within mammals, humans are one of the few species which cater to their taste preferences using spices.  One of the spices used in cooking contains the active ingredient capsaicin which causes a burning or spicy sensation when eating.   Of the mammals, humans and tree shrews are two of the few species who have been documented to consume plants containing capsicumoids as part of their diet (“Tree shrews can tolerate hot peppers,” 2018).  Chili peppers are one of the most common cooking plants containing capsaicin, a type of capsaicinoid (Tsuchiya, 2001).  Other mammals avoid the Capsicum plant species due to the spicy burning sensation caused by their consumption.  Within tree shrews, they have a mutation on the reception TRPV1 which decreased the effects of capsaicin on the receptor (Han, Li, Yin, Xu, Ombati, Luo, & Lai, 2018).  From this mutation, tree shrews were able to expand their diet due to their tolerance of capsicumoids in a similar pattern of convergent evolution. With humans, the burning sensation is variable depending on food preference of the individual but humans are the only species known to actively seek out the consumption of very spicy foods (Han et. al., 2018).  TRPV1 receptors are apparent throughout mammals in their avoidance of spicy foods but only humans and tree shrews have evolved to utilize capsaicinoids in their diet. Of other vertebrates species, birds are one of the only other species to have no response to eating Capsicum plants (Han et. al., 2018).  Birds are often used by plants to spread their seeds and it is likely that mammals do not do this job as well leading to the plant’s possible evolution to prevent their consumption by mammals.

Both between and within populations, human taste preference varies between every individual.  Within humans, an assemblage of factors affect food preference like genetics, environmental conditions, and culture (Robino, Concas, Catamo, & Gasparini, 2019).  Due to advancements in molecular genetics, the understanding of food preference as it relates to sensory perceptions is being uncovered. Not only does genes coding for the taste and olfactory receptors have an effect on food preference but novel genes also have an influence as well (Robino, Concas, Catamo, & Gasparini, 2019).  The connection of novel genes to direct genes shows the complexity of food perception in the body. Through heritability studies, there is conclusive evidence that food preference is heritable but there is another variable that also has an effect on food preference (Robino, Concas, Catamo, & Gasparini, 2019). If there is any advantage to specific foods being consumed, then these food preferences would be selected for and passed down to the next generation.  At the genetic level, DNA polymorphisms are responsible for taste and smell variations between individuals. For example, the TAS2R38 receptor detects bitter taste and just a single nucleotide mutation can lead to a variable taste perception (Robino, Concas, Catamo, & Gasparini, 2019). Within the body, there is a complex system of gene expression interacting with cultural and environmental influences which determine an individual’s food preferences.