Sunday, June 12, 2011

Optimization of PCR

Optimization of PCR is a tedious and hectic job sometime you get results very early and some time it takes too long time. I was facing the same problem when I encountered with this method. When I read this I found it a simple, fast and reliable method for the optimization of PCR. It is called the Taguchi methods. It is a statistical method developed by Genichi Taguchi to improve the quality of manufactured goods, but now it is also used in engineering, biotechnology, marketing and advertising.

With the use of Taguchi methods, the range of optimal conditions for any given PCR assay may be obtained in very little number of reactions required to optimize several different variables in a classical block titration method.

For example if 4 different variables (like dNTPs, Mg++, primer, enzyme or you can put some other variables) are tested at 3 different concentrations each, the titration would need 3X3X3X3 = 81 reactions.

However, using Taguchi methods, only 9 reactions are required.

In this method, the number of reactions (E) is calculated from   E = 2k + 1; where k being the number of variables to be tested.

Now if we increase the number of variables, for example if there are 8 variables, than we need 6561 reactions in block titration method, but only 17 reactions are needed with the use of the Taguchi method. 


Table 1
Table 2




A
B
C
Primer
7.5
15
30
MgCl2
0.5
1.5
3
dNTPs
50
100
200
Enzyme
0.5
2
5


For more details please see the following article.



Cobb, B.D., Clarkson, J.M. 1994. A simple procedure for optimizing the polymerase chain reaction using modified Taguchi methods Nucl Acids Res., 22(18): 3801-38


Friday, March 18, 2011

Orkut vs Facebook


Some days back I noticed there are either no updates or very few updates from my friends on Orkut. I also noticed that they prefer Facebook over Orkut, so I also joined Facebook. But I still thinking about the same question why people prefer Facebook over Orkut, but I did not find any reasonable answer of the question.

I used Google Trends to find the latest trend, I was totally surprised by the results that the whole world is preferring Facebook over Orkut. 


 

                                                                                 Orkut  
                                                                                 Facebook                                                                          

The same trend is seen in India also



                                                                                Orkut  
                                                                                Facebook
It means the Orkut is loosing its popularity from all over the world

Google should be worry about this and should take some immediate action to solve this issue.