Bacterial Conjugation

This short video BACTERIAL CONJUGATION represents the illustration of conjugation - one of three mechanizms that bacteria use to transfer DNA material. From animation we can see that in order to perform conjugation, the donor gene, in this case - antibiotic resistant gene, forms pillus through which the material is transfered to the recepient gene. Now both of them are drug resistant. This is direct contact from gene to gene.
Besides the conjugation, in our microbiology class we have also learned two others types of gene transfer that are TRANSFORMATION in which DNA is trasported across the cell membrane, and TRANSDUCTION in which DNA is carried into a new cell by a bacteriophage.
http://www.hhmi.org/biointeractive/media/conjugation-lg.mov

Cultured Human Embryonic Stem Cells

Cultured Human Embryonic Stem cells.

In this 1 minute and 17 seconds video, a professor was presenting an interesting subject of culturing human embryonic stem cells: embryonic stem cells can develop any type of cells. Human embyonic stem cells were allowed to grow in a cultivated dish, and these cells were able to develop and renew themselves and can differentiate. The interesting development of these cells was that some cells start to spontaneously develope muscles that can beat. These beating muscles are called cardiosites and they are just like the muscles of a human heart. There are different cardiosites and each beat with its own rate. However, these cardiosites are not organized like a human heart. They are made up multiple tiny cells grown in a dish. Although the answer to how do these cells know what to do and when to make cardiosites is still known, it gives rise to new hypothesis that perhaps the cells can further teach us about the normal development of human and a potential treatment for diseases that result from missing cell types.

How this subject is related to this course is that the subject is about cells being regenerate and cultivated. In this class, we’ll be working with bacterial organisms as well as other microbes and we will be growing new colonies in a dish probably the same way as the human embryonic stem cells was grown in. We will learn to hypothesize and test our hypothesis and come up with answers to questions like in the video. Since it’s a Microbiology course, we will be studying lots of different cell types and learn why do cells evolve and develop certain characteristics, and how these developments benefits and/or harm the colonies.

http://www.hhmi.org/biointeractive/media/human_es-lg.mov

Posted by Vy Hoang

Bacterial Growth

Dr Brett Finlay shows how bacteria can grows rapidly when there is plenty of nutreints. He explains how E-Coli can't grow without unlimited nutreints. Bacteria growth needs unlimited energy that the world doesn't have. Example: In our intestine E-Coli only grows 1 in every 24 hours, because it's fighting for the nutreints from its neighbors. How this clip relates to our Microbiology class is what we do in are labs. We do different techniques Like Streak plates, Pour Plates, Sterile Transfer Techniques to see how many colonies grow and what conditions they grow under. Also in lectures we talk about the different conditions that bacteria grow like temperature, Lag phase,log phase, stationary phase, and death phase.http://www.hhmi.org/biointeractive/video/index.html

Damage of DNA leads to mutation

Chemical changes in DNA can cause a mutation. DNA is constanly under attack from reactive chemicals and natural background radiation. Free radicals are the products of natural metabolistm in the human cells can sometimes react with DNA and cause chemical changes. In addition, radiation such as ultraviolet light from the sun could be the reason of harmful chemical changes in the DNA of skin. Fortunatly, DNA has the ability to repair itself. Most mutations can be corrected by biochemical repair work before they have any effect. However, in a few cases mutations can accumulate. One of the chemical changes in DNA is disease-cancer. Later on in class we are going to learn about mutation in DNA and its effects.

HIV's origins in Africa

I watched a video clip HIV'S origins in Africa where Dr. Beatrice Hahn discusses how HIV originated in Africa cross-species transmission from chimpanzees to humans. Dr. Beatrice spends her carrier to uncover the origins of the AIDS virus in Central Africa. Her team discovered that the viruss occured in Cameroon and was carried to Kinshase. The greatest diversity was identified in Kongo and over the Kongo River was carried to East Africa. In East Africa AIDS virus was first discovered as a syndrom. From there it was spread around the world.

Later on in this class we are going to study more about the AIDS pathogen and its virulence factors.

Penecillin acting on bacteria

http://www.hhmi.org/biointeractive/video/index.html

HIV's origins in Africa

http://www.hhmi.org/biointeractive/video/index.html

E. coli's Infection Strategy

http://www.hhmi.org/biointeractive/disease/animations.html#ecoli

South Africa: Tuberculosis

Yesterday, I watched a short video about a high rate of TB and HIV/AIDS infected population in South Africa. Tuberculosis (TB) disease keeps spreading more and more throughout our world. Currently, 30% of those who are diagnosed with HIV are also infected with TB. To add to that, 70% of those who are found to have TB, also have HIV disease. As a result, there is a big intersection between the two. Unlike HIV, TB spreads through air; for example, you can get it from someone who is infected when they cough or sneeze and you happen to be around. In South Africa there have always been two different medical centers for patients with HIV and those with TB. However, Edendale Hospital is trying to develop a program that will treat HIV infected patients as well as TB patients since a large amount of people in South Africa are infected with both. Recently, in the BIOL440 class, we saw a movie clip of TB situation in Russian prisons. Also, we learned about Mycobacterium which causes TB, and we are going to cover more topics about it in the BIOL 440 course.

http://www.hhmi.org/biointeractive/video/index.html

http://www.hhmi.org/biointeractive/media/size_analogies-lg.mov

Enzymes That Are Not Proteins: The Discovery of Ribozymes

Researching for this assignment something caught my eye that seemed very familiar. We have been studying enzymes and proteins, so this topic of "Enzymes That Are Not Proteins: The Discovery of Ribozymes" seemed like a natural fit not to mention fascinating. DNA and RNA are very similar in chemistry, but DNA has a double helix (chain) and is not flexible, where as the RNA is a single chain giving it more flexibility and the allowing it to take on different formations or interact with itself creating more variety as a biocatalyst. DNA does not have the ability to replicate itself without the aide of a catalyst and lacks an oxygen molecule, where as, RNA has an extra oxygen molecule and in some cases can replicate itself through self catalyzing because it has its own nuclei. This is where the interesting theory of the chicken and the egg, who came first? Did a self replicating RNA molecule take place? In this short video, HHMI President Dr. Thomas Cech discussed the discovery of RNA's catalytic properties and how they found this information totally by accident. We sometimes wonder who comes up with these names for different molecules well the name for Ribozymes actually came from a naming contest he held. This video clip although 19 minutes long is absolutely worth watching. As I continue to explore enzymes and proteins in class this information helps to clarify their purposes and functions for real life application.

http://www.hhmi.org/biointeractive/video/index.html
Enzymes That Are Not Proteins: The Discovery of Ribozymes

South Africa: Tuberculosis

http://www.hhmi.org/biointeractive/video/index.html

Size analogies of bacteria & viruses

Size Analogies of Bacteria and Viruses


I saw the short video about the size analogies of the bacteria and the viruses. The lecturer is comparing the size of the cell to the human, so the bacteria would be the size of the football, large viruses would be about the size of the "AA" battery, and the small viruses would be about the size of the aspirin tablet. But in the reality you won’t see with naked eyes because the very, very tiny small bacteria and viruses.

Cheek Cells and Bacteria

I saw an interesting clip about cheek cells and bacteria that is always present in our mouth. Dr. Brett Finlay did an experiment and it showed high amount of bacteria that he found in his mouth. He took a toothpick and scraped it inside of his cheek and put it on a slice. Then, he gram stained it. When he looked through the microscope, he saw two things on the slide. Those two things were his bacteria and another thing that he saw was his mynophlora. Mynophlora is picked up when you are born, and you live with it until you die. It exists in people's mouth all the time. Its everywhere and it is completely normal. Why I chose this short time clip is because I did some cheek cell experiment in Microbiology lab in the beginning of the semester. Also, we learn a lot about microbes and bacteria in class. So, this clip was a good reminder of the things I learned in class.
http://www.hhmi.org/biointeractive/media/cheek_cells-lg.wmv

Gene Transfer In Bacteria

We saw a movie clip of TB situation in Russian prisons on last thursday. The movie briefly mentioned the problems involving MDR-TB (multi-drug resistance tuberculosis) strains and the causes for their origin. The origin of these strains are mostly man-made: antibiotics used in animal feed (sub-therapeutic concentration of clinical antibiotics are often used as growth enhancers in farms), improper use of antibiotics in clinical settings, etc. A good example of evolution of a MDR strain is Staph aureus. In 1940's, one could easily eliminate S. aureus with penicillin. It's not the case anymore.

There are two major ways by which bacteria gain antibiotic resistance - lateral gene transfer via bacterial phages (viruses that infect bacteria) and plasmids (extra chromosomal DNAs found in cytoplasm that are replicate independently of chromosomal DNA, expressed only when needed).

The plasmids often carry antibiotic resistance genes that can be readily passed onto neighboring bacterial cells. They are also a very useful tool in biotechnology - cloning of any genes of interest is made possible by plasmids. Expression of human insulin in E. coli carrying genetically engineered plasmid is a good example of that. Many enzymes that are available to biologists today are cloned into plasmids.

My graduate research involved expression and purification of Listeria monocytogenes membrane proteins in E. coli. The genes that encode these membrane proteins were clones into a plasmid then expressed in E. coli. The following pictures show genes (gbuA, gbuB, and gbuC) and proteins that were expressed and isolated from E. coli:

1% agarose gel: lane 1) DNA ladder; lane 2) gbuA; lane 3) gbuB; 4) gbuC

SDS-PAGE protein gel: lane 1) marker proteins; the rest are all pure GbuA

SDS-PAGE protein gel: lane 1) marker proteins; lane 5) pure GbuB

SDS-PAGE protein gel: lane 1) marker proteins; lane 5)-8) pure GbuC

While conferring antibiotic resistance to bacteria in a lab setting can be beneficial in the context of research, uncontrolled proliferation of antibiotic resistance in deadly pathogens can be quite devastating. It is my hope that Bio440 will give you a greater understaning and appreciation of the role that we play in maintaining (or otherwise) the delicate balance of mother nature and take more responsibility for how we deal with the environment. -Min

cystic fibrosis

Information about cystic fibrosis

Help for Patients and Caregivers : Cystic Fibrosis from Central Kentucky Mobility