Vectors genomic library construction

Yeast (Saeeharomyees eerevisiae) has a genome size of 1.21 X 10 bp. If a genomic library of yeast DNA was constructed in a bacteriophage A vector capable of carrying 16-kbp inserts, how many indi-... 

Table 24.2 Comparison of vectors used for the construction of genomic libraries...

Yeast Genomic Libraries Can Be Constructed with Shuttle Vectors and Screened by Functional Complementation... 

Shuttle vectors that replicate in both yeast and E. coli can be used to construct a yeast genomic library. Specific genes can be isolated by their ability to complement the corresponding mutant genes in yeast cells (see Figure 9-20). 

Figure 1.2-1. Examples of vectors used for construction of genomic libraries (maximum capacity 24kb). Standard X vectors (XEMBL3, XGEMll, X.DASH, A,EMBL3, and A.SK6) and diphasmid vectors (XSK17 and XSK40) are shown. Sizes are in kilobases and are not shown in the scale. Not all restriction sites are shown. Heavy thick lines represent stuffer fragments open boxes mark plasmid and M13 sequences /acZO is the lac operator sequence. T3, T7, SP6-promoters for T3, T7, and SP6 RNA polymerases.

Figure 1.2-2. Examples of vectors used for construction of genomic libraries (capacity more than 45kb). Sizes are in kilobases and are not shown to scale. Not all restriction sites are shown. For more details, see the text.

In some cases, it is more convenient to work with a genomic library in plasmid than in lambda phage form. The construction of representative genomic library directly in a plasmid vector has several drawbacks and difficulties. However, these problems can be easily solved with the help of phasmid and diphasmid vectors. In this case, a genomic library is constructed in lambda phage (e.g., SK40), and then the whole library is converted to plasmid form. 

There are many different modifications to construct libraries however, the three ways to construct genomic libraries are the most commonly used and will be exemplified below using genomic lambda-based vectors (Figure 1.2-3, [12-14]). 

Figure 1.2-4. Construction of genomic library in YAC vectors. See text for more details.

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