Positive charge forces cations such as Mg++ and Ca++ to diffuse from the tubular lumen through the paracellular space and into the interstitial fluid.

#Id: 2511

#Unit 13. Methods in Biology

Glycoproteins have traditionally been detected on protein gels by use of the periodic acid–Schiff ( PAS) stain

#Id: 2512

#Unit 13. Methods in Biology

Quantitative analysis (i.e., measurements of the relative amounts of different proteins in a sample) can be achieved by scanning densitometry .

#Id: 2513

#Unit 13. Methods in Biology

Larger fragment DNA are isolated by using agarose gel while shorter fragment are separated by 3.5% polyacrylamide gels are used to separate DNA in the range 80–1000 nt and 12% gels to resolve fragments of between 20 and 100 nt.

#Id: 2514

#Unit 13. Methods in Biology

Pulsed-Field Gel Electrophoresis are used to separate very large fragment of DNA 2 × 103 kb, Essentially, this allows the separation of whole chromosomes by electrophoresis.

#Id: 2515

#Unit 13. Methods in Biology

Pulsed-Field Gel Electrophoresis involves electrophoresis in agarose, where two electric fi elds are applied alternately at different angles for defined time periods (e.g. 60 s)

#Id: 2516

#Unit 13. Methods in Biology

 PFGE has proved particularly useful in identifying the course of outbreaks of bacterial food-borne illness (e.g. Salmonella infections).