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In my mammalogy lecture last week, we learned about zoogeography and its effect on early and present day marsupials. First off, zoogeography is a method to describe the local and global distribution of species based on the environment. There are seven zoogeographical regions around the world. They are: Nearctic (modern day North America), Neotropical (South America), Ethiopian (Africa), Oriental (Southern Asia), Australian (Australia), and Palearctic (Eurasia). With the topic of marsupials, we discussed evolution and their historical regions. Most marsupials today are only found in Australia, with the exeption of the opossum and the colocolo, but millions of years ago they were in modern day Antartica and all over north and South America back when the continents were connected. When the continents split, the isolation and change in climates led to extinction of early marsupials in Antartica and most of North and South America. 

A new study, published in Nature Sustainability, shows satellite images displaying the leafy cover across the globe which has grown by 2.3% per decade since the 1980s. A main driver is the “fertilization effect” which is brought about by humans burning fossil fuels. When plants take up more gas, in this case, CO2, they produce more food and create new leaves. Researchers also found that planting more trees and crops is aiding in the growth. China and India have contributed to approximately a third of the greening since 2000, mainly by forests and farms. The satellite images revealed that only five percent of the vegetated areas are browning.

Candida albicans are fungal pathogens that infect humans. It grows in various forms either in a yeast form or a pseudohypae form. The change in conformation of Candida albicans is based on what cell type it originally is. The bacteria can be unicellular, or multicellular to determine the fate of shape. Candida albicans are harmless in general, but can lead to diseases when they over grow. Candida albicans are found mostly in patients with HIV, transplant recipients, and chemotherapy patients. The morphology of Candida albicans depend on the environment they are placed. Temperature, pH, salt concentration are all factors that potentially influence the appearance of Candida albicans. Through a method called transition, Candida albicans change their morphology. Unlike Eukaryotic cell, where gene regulation is the key factor of determinate cell, bacterial cells have a high plasticity to the environment they are in.

Energy metabolism in animals is typically calculated in three different ways. The first way is to quantify the difference between the energy value of all food consumed and energy value from waste. This assumes no change in the physiology of the animal and is typically only accurate across long periods of time. The second method for calculating metabolism is to quantify the total heat production of animals compared to the food that they consume. This method is considered very accurate but is very complex and difficult to calculate. The last method is the most commonly practiced method in the field. This third method measures the oxygen levels in oxidation processes and assumes no anaerobic metabolism. This method is generally considered to be very accurate and the source of energy (fat, protein, or carbohydrates) is not of importance. It also assumes that the amount of heat generated per liter of oxygen during metabolism is consistent.

The people who deny global warming often times do not propose solutions. They deny the fact that humans have an impact on global warming, so they do not propose ways for people to correct it. Often, they try to delay or even throw out the bills and laws people pass to try and lessen global warming. This is happening with the current president, President Trump, who is a global warming denier. He thinks that the solutions Obama had passed is waste of money. This will have a profound impact upon the earth. “President Donald Trump's planned climate change policies could lead to an extra half a billion tons of greenhouse gases in the atmosphere by 2025, according to a new analysis.” So, this bill for climate change would just take away from all the solutions of the other side. The solutions for the people who believe in climate change are to have a cleaner planet. Being a more sustainable society and having renewable energy is the best solution. For the people who oppose the idea that humans have a large impact on climate change, all the solutions seem like a waste of money. So, the formation of a solution depends on who is in power.

The Bcl-2 protein family consists of proteins that contain at least one evolutionarily conserved BH domain out of the four that exist (BH1, BH2, BH3, BH4).  Within this family, there exists pro-apoptotic proteins and anti-apoptotic proteins that interact to govern the fate of the cell. Anti-apoptotic proteins conserve all four BH domains, and include Bcl-2, Bcl-XL, Bcl-W, Mcl-1, and A1. Pro-apoptotic proteins can be subdivided into two groups, those with multiple BH domains such as Bax and Bak, and those with only the BH3 domain such as Bid, Bim, Bad, PUMA, and NOXA (Carter, 2016).

When the cell is not undergoing apoptosis, anti-apoptotic proteins such as Bcl-2 and Bcl-XL sequester Bax and Bak.  When the cell wishes to undergo apoptosis, the anti-apoptotic proteins are sequestered by the BH3-only pro-apoptotic proteins, releasing Bax and Bak, which allow the release of cytochrome C from the mitochondrial membrane, uncoupling the electron transport chain and inducing the activity of caspases. In healthy cells, p53 is a transcription factor for the pro-apoptotic BH3-only proteins Bik, Bid, PUMA, NOXA, as well as for Bax, the pro-apoptotic protein with BH1, BH2, and BH3 homology and the most downstream member of the Bcl-2 family in the regulation of apoptosis (Fridman, 2003). In high grade serous ovarian carcinoma, anti-apoptotic proteins including Bcl-2 and Bcl-xL are overactive and therefore responsible for keeping cancerous cells alive too long (Yokohama, 2017). Different studies have shown a negative correlation between Bcl-xL levels and drug sensitivity in regards to chemotherapy.

The paper investigates the divergence of cephalopods. The limited fossil record makes it difficult to find divergence times and patterns. The researchers used molecular clocking, a technique to track the timing of when groups in the cephalopod phylogeny split off from one another. Molecular clocking measures genetic mutations over time in different groups to show measure how they evolve differently, and this data is subsequently compared to their fossil records. The paper showed that cephalopods diverged during the Mesozoic Revolution, 160-100 millions of years ago. During this time there were not only dinosaurs above land, but there were also dramatic changes below the sea caused by competition. Many adaptations arose around this time in response to the competition. For example, cephalopods lost their shells, which made them more lightweight and improved their agility. Predator-prey arms races influenced many of the adaptations that arose among cephalopods. The researchers tracked when these adaptations came into existence in different groups in addition to the rate of diversification.   

The ebola virus is very complex. It has many different ways that it can evade the host’s immune system. For example, one way that the virus can “hide” is by using lipids from the host’s cells to make an outer membrane for itself. This lipid membrane tells the host’s immune system that the virus is self and to not attack it. If the virus can evade the immune system it can successfully replicate in the cells of the host. Ebola has been a documented virus for quite some time with the earliest observations dating back to the 1970s. It has only recently made headlines. This is because the virus kills the host so fast that anyone who comes in contact with it dies before the virus can find a new host. So the majority of ebola cases were very limited because infected people couldn't travel to spread it. In 2014 there was an outbreak which ended up killing more than 10,000 people. This was a new strain of ebola, the Zaire strain. This strain is just as deadly as previous ebola strains however it is unique in the fact that it has an extended incubation period, meaning that it kills the host at a slightly reduced rate. This now means that sick people are able to come in contact with more people than with previous cases. This strain is the cause of the current outbreak in which almost 1000 cases have been confirmed.