Gibberellins Enhance Cell Wall Extensibility without Acidification. Gibberellin has no effect on the osmotic parameters but has consistently been observed to cause an increase in both the mechanical extensibility of cell walls and the stress relaxation of the walls of living cells. the enzyme Expansins and Xyloglucan endotransglycosylase (XET) is involved in gibberellin-promoted wall extension. The function of XET may be to facilitate the penetration of expansins into the cell wall.

#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).

#Id: 2517

#Unit 13. Methods in Biology

DNA from Salmonella species, when digested with the restriction enzyme Xba I, gives around 15 fragments ranging from 25 kb to 680kb. This pattern of fragments, or ‘fingerprint’, is unique to that strain. If the same fingerprint is found from bacteria from other infected people, then it can be assumed that they were all infected from a common source which can be analyzed by PFGE