1-4.5.1 Examples of Phagemid:

1-4.5.1.A pEMBL

One of the first hybrid phagmid vectors was pEMBL constructed in 1983. They are characterized by the presence of –

1)  The bla gene as selectable marker for ampicillin resistance.

2)  A short segment coding for the alpha-peptide of beta-galactosidase (lacZ) and containing a MCS.

3)  The intragenic (IG) region of phage F1.

 

These vectors have been used successfully for DNA sequencing with the dideoxy method, and can be used for other purposes for which M13 derivatives are used. However, the pEMBL plasmids have the advantage of being smaller than M13 vectors, and the purification of DNA is simpler. In addition, long inserts have a higher stability in pEMBL plasmids than M13 vectors.

Fig: 1-4.5.1.A: pEMBL vector

1-4.6 Artificial Chromosomes:

Artificial chromosomes are DNA molecules assembled in vitro from defined constituents that can function like natural chromosomes.

Types of artificial chromosomes:

i)  BACs: Bacterial artificial chromosomes

ii)  YACs: Yeast artificial chromosomes

iii)  MACs: Mammalian artificial chromosomes

iv) HACs: Human artificial chromosomes

v)  PACs: P1-derived artificial chromosomes

Some of the artificial chromosomes are discussed below-