The ins and outs of centrifugation

What is centrifugation? Centrifugation is the separation of organelles in order for further analysis of specific parts of the cells, for example, the nucleus. An ultra-centrifuge containing the homogenised organelle is rotated at a high speed in order for the centrifugal force to separate the sections of the organelle with heaviest sections separating first. Each time the centrifugation terminate, a pellet is collected and analysed. Throughout the different medical sciences and chemical industries centrifugation is predominately the process of putting liquids into test tubes, placing them in the ultra-centrifuge, and spinning it to apply the centrifugal force. From this technique we can isolate parts of the organelle such as the mitochondria, the nucleus and ribosomes. Each of these providing benefits for the scientific community. By studying the nucleus we can study the DNA for any genetic estrangements and correlations within particular diseases, as with the ribosomes and mitochondria, we can study the production of proteins and respiration etc.
The product that is received is dependent on the rotation speed, rotor size as well as the solvent density. Each of which can result in different organelle sectors being centrifuged.
This use of a centrifuge is valuable to scientists because the centrifuge separates supernatant containing  homogenised organelles into layers based on their mass. Larger components of the liquid are pressed toward the outside of the centrifuge with more centrifugal force, so they settle to the bottom of the test tube. Smaller components settle in layers higher up or the supernatant, with the least massive at the top. When medical staff use a centrifuge on blood, for example, the blood cells collect at the bottom while the blood plasma moves to the top due to it being of low density.
By applying  centrifugal forces in a confined and controlled space, a centrifuge can be a useful tool not only for scientists and medical practitioners, but for other industries as well. Centrifuges are used in sewer management, in the oil industry, and also in the processing of sugar and milk. They also play a part in the nuclear power industry to separate isotopes and enrich uranium.

Sources: http://en.wikipedia.org/wiki/Differential_centrifugation
http://coursesite.uhcl.edu/NAS/StephensB/SH%20CENTRIFUGATION.pdf
www.wisegeek.com%2Fwhat-is-a-centrifuge.htm&h=DAQFB6ZjY
Author: Katie-Jo Mawson

Multiple sclerosis and research

Multiple sclerosis is an autoimmune disease in which T-cells of the immune system attack the myelin sheath (cells that surround the axon of neurons) of the sufferer’s central nervous system. In this case the body cannot recognise what is self and foreign so it destroys host cells. Legions appear in the brain and can be seen from an MRI scan. Sclerosis refers to scarring, usually in the white matter of the brain and the spinal cord, which interrupts the communication of these nerve cells and thus prevent or slow many instructions for movement, sight and memory (as well as many others listed in a link below). The cause for all this is however completely unknown, all that is known is that there is a slight genetic factor involved. By this I mean that those diagnosed with MS usually have a relative somewhere in their family who also has MS, for example my father was diagnosed in 2001 and found that his cousin's daughter also has MS, which means I have a slight higher risk of MS than those without the family link. But, and there’s always a but, there are many cases of MS that seem to have no genetic link and so by no stretch is there a causal link. This is all very confusing but what it points towards are alternative factors such as environment, age, geography etc. It is likely that genes define who is most susceptible to developing the disease, but environmental factors are what define who actually develops the disease.

 So, a virus or bacterial infection may be the trigger. Back to my father again, at the age of 10 he had glandular fever (Epstein Barr virus) many of his friends suffering from MS had the same at an early age, yet somewhat frustratingly not all MS patients have had this.

 It is also thought that a lack of vitamin D can increase risk, and research into that theory will be looked at during the course of this year.

A lot of disagreement has came about from Dr Paolo Zamboni’s claims that up to 90% of MS is caused by narrowed veins and blockages that obstruct the flow of blood from the brain back to the heart, as the theory has been undermined by a few other scientists claiming that the blood flow is normal in MS patients.

There are many theories such as Zamboni’s that remain very much unclear and one could potentially hold the answers we’re looking for. 

If you’re interested in other research into the cause of MS please visit this website: http://www.mssociety.org.uk/ms-news-and-research/ms-research/research-projects/cause#CD86

And if you’re wanting to looking into symptoms: http://www.mssociety.org.uk/what-is-ms/signs-and-symptoms?gclid=CKSa7LnP-K4CFdISfAoddRy61A

Other resorces:

http://www.bbc.co.uk/news/health-16086004

http://www.chg.duke.edu/diseases/ms.html

http://www.multiplesclerosisinformation.co.uk/#/about-ms/4534155497

http://www.klearview.co.uk/MS.html

http://www.mult-sclerosis.org/blog/

http://www.knowswhy.com/why-is-multiple-sclerosis-an-autoimmune-disease/

http://articles.latimes.com/2010/aug/02/science/la-sci-ms-treatment-20100803
Author: Grace Ronnie

Gill lamellae.

Today in Biology we were all let loose with some scalpels and a pair of scissors with the attempt of finding the gill lamellae in fish heads. The experience taught us more about the satisfaction you can get from mauling the eye out of dead fish, than what the actual purpose of the gill lamellae is.

Above: The delightful Grace holding the product of 40 minutes dissection.

The gill lamellae is an important respiratory structure in the gills of a fish, it uses the idea of a countercurrent flow, which is where a constant low diffusion gradient is necessary to transport oxygen around the respiring tissues. This system is efficient due to the use of at least 75 per cent of oxygen from the water. These structures are founded upon gill filaments which are stacked upon one another. The lamellae are important as they increase the surface area of the gills which in turn increases the rate of diffusion withing the fish itself.
The countercurrent flow system previously mentioned is a more effective method of diffusion of oxygen than the system us mammals possess; parallel flow. This is because the blood and water which flow over the lamellae do so in opposite directions. This means that blood that is well loaded with oxygen meets water, which also is well loaded with oxygen. Therefore little, but sufficient, oxygen will diffuse over the small diffusion gradient into the blood. The system also ensures that when the water contains little oxygen, diffusion will still occur. This is because there will always be a diffusion gradient favouring the diffusion of oxygen from water into the blood all the way across the gill lamellae hence then 75 per cent oxygen use.
Contrasted with the countercurrent flow, the diffusion system we posses only uses up a maximum of 50 per cent of oxygen available for diffusion due to the gradient being cancelled out. This is because of the flow of water and blood being 'parallel' to each other, creating a high diffusion gradient between the water's high saturation of oxygen, and the blood's low saturation of oxygen.
Fish contain these structures as they have a small surface area to volume ratio meaning they would simply not be able to survive without developing a specialised internal gas exchange surface.


Sources: AQA AS Biology textbook and Mrs Palmer, biology teacher.
Author: Katie-Jo Mawson

Brief on intragenic regions and research

Introns are sections of DNA that don't code for any instructions or proteins: non-coding sections. They can be found in pre-messanger RNA as well as the parts that code for proteins (exons). Pre-mRNA goes through a modification process (splicing) to produce the mRNA of only exons. The question now posed to scientists is: why do introns exist and what is their purpose? The questions are yet to be definitely answered, so it leaves plenty room for research for those of you who may be interested. The most popular belief is that they’re caused by evolution. Introns in modern genetic material could have been a gene in ancestral genetic material that proved not to be strong enough to last and was weaned out by natural selection. Or, the introns exist to leave room for new genes to be created. However, there have been recent breakthroughs in understanding them more; in a study conducted at Indiana University Bloomington and University of New Hampshire, there showed considerable proof to point toward the theory of “hot spots”, these are loci on the complete genetic material where introns seem to be likely. This contradicts prior belief as it would point towards introns being actually quite common instead of a rarity. 

References: 
http://www.sciencedaily.com/releases/2009/12/091210111148.htm

http://www.rae.org/introns.html

https://www.utoledo.edu/med/depts/bioinfo/pdf/facpdfs/fedorova10.pdf

Author: Grace Ronnie