Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi or parasites and can spread between individuals. 1  Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi or parasites.2  Microorganisms that cause disease are collectively called pathogens. Many diseases become difficult to control if the infectious agents evolve resistance to commonly used drugs: 2  For example, bacteria can accumulate mutations in their DNA or acquire new genes that allow them to survive contact with antibiotic drugs that would normally kill them.
Southern blot. A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization.
However, the entire process is commonly referred to as northern blotting. The northern blot technique was developed in 1977 by James Alwine, David Kemp, and George Stark at Stanford University.Northern blotting takes its name from its similarity to the first blotting technique, the Southern blot, named for biologist Edwin Southern.ith northern blotting it is possible to observe cellular control over structure and function by determining the particular gene expression rates during differentiation and morphogenesis, as well as in abnormal or diseased conditions.