just for fun: Nikon's small world photomicrography competition

I was perusing on the good ol' internet when I stumbled upon this really neat competition that Nikon has every year.

Quick introduction (taken from the website http://www.nikonsmallworld.com/):

"Small World is regarded as the leading forum for showcasing the beauty and complexity of life as seen through the light microscope. For over 30 years, Nikon has rewarded the world's best photomicrographers who make critically important scientific contributions to life sciences, bio-research and materials science."

Rules: http://www.nikonsmallworld.com/rules 

  

There are some really cool pictures. 

The winning picture (shown below) for 2011 was from Anna Franz. 

Ink injection into yolk sac artery of 72 hour-old chick embryo to visualize the beating heart and the vasculature (reflected light technique)

 

Technique: What is RNA interference?

The central dogma consists of
DNA --> mRNA (via transcription) --> protein (via translation)

RNA interference/RNAi is the silencing of RNA for controlling gene expression. This occurs naturally. Scientists have been able to use RNAi as a tool for studying gene expression, drug target screening, and for development of therapeutic drugs. 

1. Double stranded RNA is cleaved into small interfering RNA/siRNA by the RNAseIII enzyme called Dicer.
2. The siRNA are incorporated into silencing complexes that will target messenger RNA/mRNA for cleavage.
3. The mRNA that is coding for a specific protein is degraded, and there won't be any protein expression.

Information was obtained from: http://www.vet.uga.edu/id/tripp/RNAi.php

http://www.vet.uga.edu/id/tripp/RNAi.php

This video was obtained from youtube. The original link for this video is: http://www.nature.com/nrg/multimedia/rnai/animation/index.html

http://www.nature.com/news/2009/090624/images/_tmp_articling-import-20090624083219872961_4591047a-i1.0.jpg

Richard Jorgensen is a molecular geneticist, who is an early pioneer in the study of RNAi. In the 1980s, he was asked to create purple petunias by a biotechnology company. He introduced the gene that coded for the color purple into the plant, and unexpectedly the petunias did not turn purple. A defense mechanism called RNAi was set off, and it deactivated all pigment genes in the plant.

This information was obtained from: http://www.oprah.com/health/RNAi-Based-Treatments-and-Possible-Cures-for-HIV-and-Cancer

Here is a link to the video from Nova: http://www.pbs.org/wgbh/nova/body/rnai.html

A few years after, another group of scientists also noticed this gene silencing effect in C. elegans. Andrew Fire and Craig Mello, were awarded the 2006 Nobel Prize in physiology or medicine for the discovery that RNAi is triggered by double stranded RNA (paraphrased from http://www.nigms.nih.gov/News/Extras/RNAi/factsheet.htm).

Technique: Parabiosis

This past week in my developmental biology class, I learned about this really cool method called "parabiosis" that scientists use to study physiology.

Parabiosis is a method that joins two animals together physically and vascularly (they are exchanging blood). This model is analogous to making Siamese twins. It allows for scientists to learn a lot about physiology.  
Berntson, Gary G., and John T. Cacioppo. Handbook of Neuroscience for the Behavioral Sciences. Hoboken, NJ: Wiley, 2009. Print.

Parabiosis was used most famously to study leptin. 
Coleman, D.L. A historical perspective on leptin. (2010). Nature Medicine, 16, 1097-1099. 
historical perspective on leptin

Using the parabiosis model, Dr. Douglas Coleman was able to predict the presence of leptin and its receptor, 25 years before they were cloned. Here is a summary of his experiment. This was taken from the article (figure 2) mentioned above.

Leptin is a lipostatic signal that is produced by the ob gene, and its receptor is produced by the db gene.

• In part A, a db/db animal is paired with a lean animal. The db/db animal is producing leptin, but not its receptor. From this we can conclude that the db/db animal is producing something (leptin) that is promoting a decreased in food intake and blood sugar. 

• In part B, a db/db animal is paired with an ob/ob animal. The ob/ob animal has leptin receptors, but is not producing leptin. From this we can conclude that leptin from the db/db animal is promoting a decreased in food intake, insulinemia, and blood sugar. 

Remember that the animals are joined by their circulatory system.

• In part C, an ob/ob animal is paired with a lean animal. The ob/ob animal has a decrease in food intake and blood sugar, while there isn't a change in the lean animal. The lean animal is able to make leptin.

• In part D, two lean animals are paired together. There isn't a noticeable change in their physiology.

Dr. Coleman and Dr. Friedman (the guy who cloned the ob and db genes 25 years after Dr. Coleman's studies) won a Lasker award for their research about leptin and its receptor. 
http://www.jci.org/articles/view/45094

Dr. Douglas Coleman  (http://www.maineahead.com/vantage-point%E2%80%93doug-coleman/)

Dr. Jeffrey Friedman (http://www.nature.com/nm/journal/v10/n2/images/nm0204-116-I1.jpg)