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The visual system of most deep sea organisms is able to detect short-wave blue wavelengths. Loosejaw dragonfish are able to detect longer wavelengths of light and emit these wavelengths as the color red through bioluminescence. Because red light does not penetrate deep into the ocean, the red visual system allows organisms with the adaptation to communicate with each other specifically, and in addition, it allows predators to catch unsuspecting prey by surprise using bioluminescence. This paper focuses on uncovering the evolutionary history of this phenotype in the family of Stomiidae. The authors sought to understand the timing of the evolution, the number of times the trait evolved, and whether it arose due to positive selection. The findings for the evolution of the red visual system were more complex than expected. The red visual system was found to have evolved once as a single evolutionary event within loosejaws. They found that at approximately 15.4 Ma, far red visual systems evolved and at 11.2 Ma the primitive blue visual system re-appeared in the most recent common ancestor of dragonfish. The authors also investigate the phylogenetic relationships between Stomiidae and found that the relationship between this family and loosejaws is paraphyletic. The significance of this study in the context of spectral tuning in deep sea organisms is that it provides a phylogenetic approach to analyzing the evolution of the red visual system.

The visual system of most deep sea organisms is able to detect short-wave blue wavelengths. Loosejaw dragonfish are able to detect longer wavelengths of light and emit these wavelengths as the color red through bioluminescence. The authors sought to understand the timing of the evolution, the number of times the trait evolved, and whether it arose due to positive selection. The findings for the evolution of the red visual system were more complex than expected. The red visual system was found to have evolved once as a single evolutionary event within loosejaws. They found that at approximately 15.4 Ma, far red visual systems evolved and at 11.2 Ma the primitive blue visual system re-appeared in the most recent common ancestor of dragonfish. The authors also investigate the phylogenetic relationships between Stomiidae and found that the relationship between this family and loosejaws is paraphyletic. The significance of this study in the context of spectral tuning in deep sea organisms is that it provides a phylogenetic approach to analyzing the evolution of the red visual system.

Metastatic pancreatic adenocarcinoma is driven by cancer stem cells, formation and upregulation of the premetastatic/metastatic niche, EMT, and the largely hypoxic state of the tumor microenvironment (TME). These characteristics of metastasis feed into each other continuously to further the development and distribution of the cancer. Cancer stem cells serve as the central driver of metastasis due to their inherent plasticities and contribute to chemoresistance, functioning of the premetastatic niche, and induction of EMT (Sancho et al. 2016). In the premetastatic niche, extracellular signaling contributes to a TME that facilitates the development of the cancer. EMT allows cancer cells to detach from a tumor site and relocalize, as well as change their phenotype to a less differentiated state. When tumor growth reaches a critical point, cancerous cells deprive their environments of oxygen, leading to hypoxia and potential metabolic shifts such as the Warburg effect or oxidative phosphorylation (Sancho et al. 2016).

I thought that the authors did an excellent overall job of not only proposing a controversial hypothesis, but also backing up the hypothesis with real life data and calculations. I especially liked how they combined both factual data from living organisms and educated hypothetical data to construct and support their theory. The authors also provided detailed tables with their data along with figures to help illustrate some of the points that they were alluding to. Also, because some of the data that they came up with was hypothetical or estimated I thought it was a logical idea to underestimate their calculations. The one issue that I had with the paper was that the methods section was inserted at the end of the discussion. I would have liked to know the methods before reading their statistical results.

    Oxytocin is a hormone that is known as the “love hormone”. Oxytocin is released when acts of love and bonding occurs such as hugging. Oxytocin is secreted in high levels during breastfeeding and in relationships. Doctors started to prescribe oxytocin to children with autism, schizophrenia and social anxiety disorders. Oxytocin can change the intensity of the reaction but it would not be able to turn it on or off. Evidence has shown that women with high maternal care and strong relationships has shown high levels of oxytocin. Also there is a high level of oxytocin in women in depressive states and distressed relationships.

To further back up this claim the authors performed a parameter study to assess the sensitivity of their prediction. Mass was not the only important factor in determining their hypothesis. They also looked into limb orientation, and muscle fiber lengths. Since these data points cannot be determined for sure the authors used conservative assumptions leading to an underestimated value of required muscle mass. They used T as the minimum extensor muscle mass per leg and determined that if T  is 5-25% body mass per leg than the biped could not run fast due to the lack of necessary muscle force. Hutchinson and Garcia’s model predicted that the T value for Tyrannosaurus was between 10-21% per leg which is not adequate enough for it to be considered a fast runner.

Hutchinson and Garcia used data from extant animals to help support their claim. They looked at the muscle anatomy of different animal’s hips, knees, ankles, and toes in order to come up with a sufficient comparison to Tyrannosaurus. Also due to fossilized footprints they had data present for small tyrannosaurs. Other animals that were used in comparison include: alligators, chickens, and the extinct Colelophysis. In comparing the muscle percent of the alligator and the chicken they found that the chicken has a larger percent of muscle mass per body mass than alligators which allow them to run faster. This is due to scaling principles predicting that animals of larger body mass have a more restricted locomotor performance. In order for the Tyrannosaurus to be a fast runner it would need enough muscle mass to support its body the authors argue. The authors calculated that the dinosaur would need about 43% of its body mass to be muscles in each leg alone in order to be a fast runner.

The threshold in a membrane potential is reached when there is a significant depolarization which opens the voltage gated Na+ channels a the axon hillock. The diffusion of sodium causes the membrane to have a positive membrane potential. The Nernst potential is then reached at +50 mV, causing the Na channels to inactivate and the K+ voltage gated channels to open as they are triggered by a delayed depolarization. K+ ions will exit until the potential overshoots the resting potential before returning to roughly the K+ Nernst potential.

In the reading by John R. Hutchinson and Mariano Garcia, the two authors propose a controversial concept that large theropod dinosaurs such as Tyrannosaurus were not actually fast runners. They use a method for gauging running through a model system that works for estimating the speed of living species such as alligator and chickens.The authors point out that this concept of Tyrannosaurus being a slow runner is not a new idea. There were earlier assessments based off of biomechanics that suggested the dinosaur was limited in locomotive performance. These early ideas were not widely accepted due to the uncertainty of the dinosaur’s anatomy, physiology, and overall behavior. However other previous studies estimate that Tyrannosaurus was able to run in the range of 11-20 m/s.