November 2011 Archives

Drosophila are one of the most studied species in the world, offering a great number of answers to complex questions. While a fly fundamentally different in many ways to a mammal, it has proven useful in the past to study flies first because they are easily examined and then to apply to knowledge gained in those studies to mammals. The visual system of flies-that is everything but the actual eye, which is admitted to be fundamentally very different from vertebrates,-is believed be similar between flies and mammals, especially the of the circuitry connecting the retina to the brain. So a publication was put out talking about fly eye targeting to satisfy the curious.

As it turns out, a fly eye starts the process of neuron targeting by sending axons out of retina into a layer of tissue called the lamina. Some of the axons sent into the lamina form a connection to various cells there, which work to process/detect motion. Another set of cells (although some of them have similar labels to the motion detecting cells) send their axons past the lamina to a layer of tissue called the medulla. The medulla is separated into six regions and each of the axon from the retina that has passed the lamina targets one of these specific regions. The axons placed into the medulla are responsible for color processing and work to signal different parts of the fly's brain about color. Both sets of neurons (the ones for motion and color) use hedgehog to locate their exact resting location in the cell. Of course, a handful of other proteins are used too and things become fun.

The actual article is extortionately in depth and would take a paper just as long as the journal article to write about. However, it does give a much more detailed account of the generally too simply and incomplete overview have given. Read up, if you'd like.

Busy Beavers and Huge Fish

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Doing research for a paper due this week, I stumbled across an interesting article published in 1974. The article described observations made by a group of scientists on a den of beavers which they claim ran on 27 hour circadian rhythm for months at a time. I went to do some more research on the validity of the claim and found no evidence supporting this journal article in the last thirty-five years, except from beaver lover blogs. The article suggested because of the extreme dark experienced in the dam, beavers set themselves to a social circadian rhythm. I thought the idea of other animals being zeitgebers was interesting, but so far, no other evidence has led to this conclusion. Somethings are just too mildly interesting to be true, ah?

I stumbled into another article this weekend while trying to find information on paddlefish. I thought this article was interesting too because so much effort was put into finding one of these fish and still no results were obtained. The Chinese paddlefish itself is pretty interesting because of the sensory rostrum, which is used passive electrical detection is long and thin, in contrast to the American broad and long rostrum. The species in heavily endangered so I doubt any research will be coming out soon or for that matter, ever regarding the function of the nose. The fish still looks pretty cool and if anyone digs up some stuff on this beast, please let me know.

Arc and Memory

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The gene, Activity-regulated cytoskeletal protein or Arc is known for its role in the storage of long term memories. Arc was first identified as having this role when mice with the gene knocked out displayed totally normal short term memory but had close to zero long term memory. The gene activates when promoted to do so from a handful of singling proteins which are activated by a handful of neurotransmitters, and when activated, in a single statement, Arc simply creates dendrite projections fairly quickly after being stimulated (within a hour). The expression of Arc happens in waves, the first which happens within the hour of the stimulation, the second follows a few hours later, and the third sometime after. The reason for expression in waves in not completely understood but it is believed the initial waves are preparatory activity, like most things biological, which creates feedback loops activating more genes which eventually allow for proper expression of the gene.

While Arc is not known to have any direct roles in disease, in Arc knock mice are known to be highly prone to seizures. I wrote about this article because as someone who experienced seizures for many years of my life I found it interesting. Pentobarbital is a drug I was put on for a short while which caused my seizures to get worse, this drug works deregulating singles across the entire brain. While, it is stated working on the whole brain equally, its use as a sleep aid and to treat people with traumatic injury, one could assume it works particularity heavily on the hippocampus. Arc, in order to work, need a ton of different singling molecules and so one would assume the function of the gene (with all its feedback loops) would probably be affected by Pentobarbital. This would explain why a fairly large number of patients who take Pentobarbital also experience an increased number of seizures, as it is also known a lack of expression of Arc causes seizures. Pentobarbital is no longer prescribed as a primary treatment to seizures (usually other things are tried first) but I would be interested in knowing if Arc is the reason why increased seizures are experienced.

If you would like to read the journal article it can be found here, and please don't stop taking your medicine, I am not a healthcare professional and this is not medical advise.

Genes, Coffee, and a T-Shirt

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One of the most widely consumed substances in the world is coffee. Known by most of us for its smell, great taste, and awaking affects, coffee is a regular part of people's lives. On top of the great things we consciously know coffee does, it also decreases an individuals likely hood of developing Parkinson's disease, dementia, and Alzheimer's disease. Coffee's stimulating power, caffeine, has been well investigated however, it is still not clearly understood why coffee, as opposed to other caffeinated beverages, reduces one's chances of developing certain neurologically diseases.

Recently however, CYP1A1 and CAB39L were announced as possible candidates of the effectiveness of coffee at neurological disorder prevention because both showed activity when coffee entered into cells. CYP1A1 was down-regulated as coffee entered cells, while CAB39L was up-regulated around the same time. CYP1A1 is known to metabolize polycyclic aromatic hydrocarbons, coffee is known to have these polycyclic aromatic rings (interesting that this could be beneficial in some manner, ah?). CAB391L on the other hand is known as a calcium binding protein. A direct correlation has not been established between the activity of these genes from coffee consumption and the decrease in neurological diseases.

I thought this study was neat because it addressed a particular substance that was not an isolated chemical. The article seemed to still be very thorough in its methods even with an enormous sample size and rather difficult topic to approach. The article is fairly detailed, read up if you would like to know more.

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