lpotter's blog

Today in class we did a simulation of the west nile virus. It was very informative. I had no idea that west nile virus was a disease that lives primarily in birds. It only kills some birds, a lot can harbor the disease and will be a permanent reservoir. The way it gets to humans is through mosquitoes. The mosquitoes bite the birds and almost always become infected, the infected mosquitoes then come and bite humans. Humans typically only come down with very mild symptoms but they can occasionally develop serious neurological issues. This usually results in death. West nile virus has only been documented in the United states since 1999, so it has been in the country for less than 20 years. It was first documented in New York and quickly spread throughout the country. The reason it was able to spread so quick is because no one realized that birds were the reservoir for the virus. This virus is also really prominent is Massachusetts. Something that I was totally unaware of. I wasn’t aware that the virus was relatively not that bad for humans to contract. I believe only 1 in 100 people suffer serious side effects from it. Regardless the disease is scary because of the way it spreads and because of the fact that it will always have a reservoir.  

This is the observed results and conclusion for my bacterial motility experiment.

Observed Results:

For the motility agar test the agar inoculated with P. mirabilis was entirely purple. This demonstrated that tetrazolium salt had been reduced by bacterial cells, in order for this to happen the bacteria must be motile showing that P. mirabilis is motile. For the motility agar inoculated with S. aureus only the area of inoculation was purple meaning only S. aureus was only able to reduce the tetrazolium salt in its immediate vicinity showing that it is non-motile. The results for the chemotaxis plates were not as expected. The plates inoculated with E. faecalis (plated by Liam Potter) showed no growth on either the control or test plate. The plates inoculated with S. marcescens (plated by Christina Fruciano) showed growth but not motility. On the control plate colonies of S. marcescens grew on both halves of the GYE agar. On the test plate S. marcescens grew on the GYE agar but not on the water agar, it did not move from the inoculated water agar to GYE agar as expected.   

Conclusion:

The organisms tested on motility agar behaved as expected. S. aureus did not reduce all of the tetrazolium salt in the agar because it is non-motile. P. mirabilis did reduce all of the tetrazolium salt in the agar because it is motile. The organisms tested on the chemotaxis plates did not behave as expected. E. faecalis did not grow on either the test plate or control plate. This may have been due to cells in the inoculum being dead or due to a plating error. The results couldn’t confirm that E. faecalis was either motile or non-motile because there was no cell growth. S. marcescens did not travel across the filter paper after being inoculated on the water agar, nor did it form any colony on the water agar. This may have been due to nutrients not being properly absorbed by the filter paper causing no chemical signal to be present for S. marcescens. Another possibility is that the inoculated cells may have died on the water agar due to lack of nutrients. Based of the observed results S. marcescens is non-motile contrary to the expected results.

This is the expected results for my bacterial motility experiment.

Expected Results:

Motile organisms were expected to move from the point at which they were originally inoculated. The first way motility was tested was with a motility agar, this agar contains tetrazolium salt and will turn purple after it is oxidized. The two organisms tested were non-motile S. aureus and motile P. mirabilis. The agar inoculated with S. aureus was expected to only be purple at site of inoculation due to the fact it is non-motile and will not reduced the tetrazolium salt it is not immediately next to. The agar inoculated with P. mirabilis was expected to be entirely purple because it is a motile organism. This result would show that all tetrazolium salt had been reduced which means P. mirabilis moved to that part of the agar. The second test was to determine if an organized displayed taxis. The expected results were that S. marcescens would exhibit chemotaxis (the ability to detect and respond to different chemicals). Chemotaxis was expected to be displayed by the motile organism, in this case S. marcescens, by traveling from the nutrient poor water agar across a piece of filter to the nutrient rich GYE agar. E. faecalis is non-motile, it was expected to stay on the water agar and not grow due to the fact that it can not move nor does it display chemotaxis.

The expected results were that gram positive endospores would survive pasteurization at 70 degrees celsius for 15 minutes. Endospores were expected to be isolated because the isolated microorganisms were coming from a soil sample. Soil is relatively low in nutrients and nutrient deprivation is what causes endospores to form. Some bacteria have the ability to produce endospores by sporulation. Because endospores are dehydrated (leaving them metabolically inactive) and covered in a thick layer consisting of peptidoglycan and proteins, they are able to withstand high temperatures. The soil samples were pasteurized at 70 degrees celsius in hopes that all vegetative cells would be killed and only protected endospores would be left. The endospores were expected to be gram positive due to their thick peptidoglycan layer, a defining characteristic of gram positive organisms.

This is my lab write for an endospore experiment.

Expected Results:

The expected results were to find gram positive endospores that survived pasteurization at 70 degrees celsius. Isolation of endospores was expected because microorganisms were being isolated from a soil sample. Soil is relatively low in nutrients and nutrient deprivation is what causes endospores to form. Some bacteria have the ability to produce endospores by sporulation. Because endospores are dehydrated (leaving them metabolically inactive) and covered in a thick layer consisting of peptidoglycan and proteins, they are able to withstand high temperatures. The soil samples were pasteurized at 70 degrees celsius in hopes that all vegetative cells would be killed and only protected endospores would be left. The endospores were expected to be gram positive due to their thick peptidoglycan layer, a defining characteristic of gram positive organisms.      

Observed Results:

The pre-pasteurization plate resulted in a lawn. There was no isolation. There were different colored colonies, white, grey, and beige, these colonies were not isolated there was a change in color across the lawn. The post-pasteurization plate resulted in minimal isolation. The were four separate isolated colony types, white rhizoid, white circular (this colony was used for gram stain and phase contrast microscopy), white irregular, and a milky beige irregular colony. After conducting a gram stain and viewing the slides under a light microscope, the stained cells appeared as purple bacilli. The wet mount (which used cells from the same isolated colony as the gram stain) when viewed under a phase contrast microscope resembled bacilli with a circle inside of it. The resulting cells fit the description of a sub-terminal endospore.   

Conclusion:

The observed results were consistent with expected results. Gram positive endospores were expected to be isolated after pasteurization and they were. When observed under a microscope the cells appeared to be sub-terminal endospores. From the performed experiments we can conclude that soil does contain gram positive endospores. We can also confirm that pasteurizing the soil will still result in undamaged endospores demonstrating that they are heat resistant.

Results

The original figure and replicated figure have many differences. The most apparent difference is the amount of photos making up each figure. The original figure consists of three photos while the replicated figure only consists of two photos. The replicated figure doesn’t include an interspecific interaction, additionally there is no arrows in the photo depicting an interspecific interaction. The replicated figure is also missing a photo of the dog by itself. The black outline of photos were different between the figures but consistent within. The map of campus where the observation took place was marked with a circle in the original figure and with an oval in the replicated figure, additionally the map was located on different sides of the original and replicated figures. The campus map is cropped on the replicate figure but not the original.

Discussion

The most major difference between figures (an absence of a photo in the replicate) was most likely due to the fact that the person observing the interspecific interaction was not able to observe the interspecific interaction. This would also account for an absence of arrows highlighting both species involved in the interaction. The black outline of the photos may be different because different editing softwares were used, this would also account for the orange circle being different on marking of the campus map. The campus map being cropped on the replicate but not on the original may be because the software used for making the replicate only allowed for a smaller image file.

Introduction

For the course writing in biology students were instructed to create a figure representing an interspecific interaction. The goal of the assignment was for each student to write a methods section that could be followed by a peer in the class. The peer was ultimately attempting to replicate the original figure based solely off of the methods section. The replicate figure was compared to the original and analyzed for the purposes of writing a scientific paper.

For selecting an interspecific interaction subjects were observed around the campus of the University of Massachusetts Amherst. In the North East area of campus an interspecific relationship was observed between a dog and the dogs owner. This was a clear example of an interspecific relation, this relation would be the one documented. The observation of the relationship was controlled by designating an area of observation. Another control was time of day, the relationship was observed in daylight, a necessity to capture photos of the subject.

Lassa virus is a very severe virus that kills nearly 20% of those infected with it. The most interesting thing about this virus is that it is rarely spread from human to human. It is mostly spread through a vector, which in the case of Lassa virus are rodents. This virus is also primarily spread in places where people are in close contact with rodents. In a area in which rats or mice travel from home to home. The virus doesn’t affect the rodents it just lives in them, so they are essentially a reservoir of the virus, they just keep giving and giving. This is very scary in countries where sanitation is poor and rodent control is minimal. Another problem is the virus can live in the rodents experiments and saliva. So when a rodent sneaks into a house and maybe takes a bite out a loaf of bread and people don’t notice or choose to eat it anyways because that is their only food source they can become infected with the Lassa virus. The problem why Lassa is so bad is because it just seems like a common cold or flu for a while so it goes undiagnosed relatively often. But after a certain period of time those infect start to develop a hemorrhagic fever. This means that blood vessels begin to break and host starts internally bleeding. This can cause a lot of internal problems and also causes the body to become rapidly dehydrated. Blood also comes out of the body's orifices. Something that can further transmit the disease.  

I know this isn’t exactly science related but it is related to physics and it was a test that I did. It was on calculating fall damage in fortnite. In fortnite you can building stairs, walls, floors, and pyramids. For my test I used walls to calculate fall damage. The first test I did was three walls up, I walked straight off the side, no fall damage. The first time I experience fall damage was from 3 and ⅔ wall height. The way I got ⅔ of a wall was by using my ability to edit the wall, you can break it into thirds. This first damaging fall dealt 11 damage, which isn’t too significant considering you get 100 health. When you jump from 5 walls high you start to experience significant fall damage, at this height I was dealt 49 fall damage. Jumping from 6 walls high deals 99 fall damage. A death fall would be from 6 and ⅓ walls high. I had a lot of fun figuring this out. I went into playground mode and got a lot of items that I could use to heal before I did the experiment. If anyone does this again and gets different numbers I would be curious to find out what they are.

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.