Filtering and replacing from multiple coloumn : I have a file where i have to replace  pvalue greater than 0.05 (pval > 0.05) with NA , in other words retain the pval < 0.05 and replace pval > 0.05 with NA . 

For example : 
Rv_FC    Rv_Pval  Gc_FC  Gc_Pval ......
2          0.001   3      0.99
3          0.99    1      0.0002
3          0.0001  2      0.89
Output :

Rv_FC    Rv_Pval  Gc_FC  Gc_Pval ......
2          0.001   3      NA 
3          NA      1      0.0002
3          0.0001  2       NA

Only pval coloumns should be considered and if the value of them > 0.05 , it should be replced with NA.

Advantage : pval coloumns are in 3rd, 5th , 7th ... coloumns.. 