Human Genome Project

I am relooking at some notes and slides I prepared for this topic. Its an interesting topic not only because of the science behind it but also the ethical, social and legal implications (that makes the acronym "ELSI") which blur the lines between right and wrong. Here are two very good resources

The first is the NOVA programs. The videos capture authentic situations that individuals face with regards to genetic diseases and also feature the scientists, science behind the project. Its more information packed in multimedia than I can summarize in a set of lecture notes. More information meaning the drama of the video that will contribute to affective learning and hence motivate students to learn more about the subject.



The 2nd is this free,... yes free, online book you can download. Its easy to read and the examples giving illustrate clearly the perplexing "ELSI" issues about genetic testing, abortions, genetic determinism... that will surface once genetic tests become more accessible..



Think ELSI and genetic testing are still far off... well read this groundbreaking and probably as "Brave New World" as it can get article in the New York Times on how you can pay just under USD$1000 for the company 23andMe to scan your genome for 580,000 SNPs (Single Nucleotide Polymorphisms). You actually can order the kit.. not sure how it works but I guess you can do it at home for yourself and children. There are at least 3 companies who will do that for around that price.


Just spit..




This NYT journalist got her own genome scanned by just spitting saliva into a little test tube . Here's a snippet of the article titled "My Genome, Myself: Seeking Clues in DNA"

"I don't like brussels sprouts. Who knew it was genetic? But I have the snippet of DNA that gives me the ability to taste a compound that makes many vegetables taste bitter. I differ from people who are blind to bitter taste -- who actually like brussels sprouts -- by a single spelling change in our four-letter genetic alphabet: somewhere on human chromosome 7, I have a G where they have a C."

But that's just information.... trivia about your genes. It gets more serious when people actually use that information to determine the genetics of their progeny. This couple actually had their daughter "genetically determined" so that she wouldn't inherit forms of genes that would make her highly susceptible to a certain form of colon cancer. This testing is termed preimplantation genetic diagnosis, or P.G.D., which means you need to cull embryos to get the right one. An eight-cell embryo has gone through fertilization.

For this couple, 4 were culled leaving 10 good ones that didn't have those forms of genes that cause cancer, 2 more were culled when a Down's syndrome test was done. Think that is unethical? Well there are people who actually remove their large intestines or breasts as a prophylactic measure against such cancers once they find they harbour just the forms of genes that make them susceptible. They may have siblings who have died because of that disease. Watch the 3rd video called One Wrong Letter in the set of videos on Nova and you will know why it becomes so grey.

(thanks to Kevin Lam who pointed out the genome scan link).

Bacterial Biofilms

This recent article in PLoS Biology gives a very readable review of bacterial biofilms and the kinds of problems they pose in medical settings. A familiar example of a bacterial biofilm is plaque on our teeth. Bacteria, when they reach a certain critical density on a surface, begin to aggregate and secrete a slimy polymeric matrix which aids further establishment and eventually builds up to a complex structure with channels and pores through which fluid can flow, carrying in nutrients and carrying away waste materials.

A few interesting points to think about:

• The means by which the bacteria detect the critical population density needed to form biofilms is called quorum sensing. How does it work?
  
• Previously it was thought that the slimy matrix protected bacteria by preventing them from being engulfed or attacked by other cells or substances, but the matrix has to be permeable to most substances because waste and nutrients must reach the bacteria. So how do they defend themselves?
  
• Biofilms usually form on surfaces over which there is regular fluid flow. Why would the biofilm growth form be advantageous?
  
• Bacteria living in biofilms reproduce at a slower rate than free living ones. How might this be understood by analogy to life-history trait selection in r- and K-selective environments?
  

GM foods are ubiquitous

Almost all the varieties of rice grown in Southeast Asia are genetically modified. A conspiracy by governments and biotech firms to reap big bucks while penalising ignorant consumers and poor farmers? No. They have been 'modified' by "accidentally as the result of mutations, chromosomal recombinations, translocations of pieces of DNA and even deletions of sections of DNA. This rice is consumed everywhere without the requirement of any laboratory tests," as this article rightly points out. Are GM foods the enemy, as some organic food advocates say that they are, or is this moralising about GM foods costing lives which could be saved by improved crop yields?