Chapter 17
Genomic libraries
LUIZ F. ONUCHIC AND GREGORY G. GERMINO
lntroduction
Library construction and screening are essential techniques that permit the
isolation and manipulation of a DNA sequence of interest. A library of
clones, whether derived from genomic DNA or mRNA, is a set of molecules
that, ideally, faithfully represents the entire population of molecules that are
in the source material from which the librarywas made. DNA fragments and
DNA copies of mRNA (complementary DNA, also called cDNA), however,
cannot propagate without assistance. Therefore, these molecules are cloned
into biological vectors which provide the necessary cellular machinery required for DNA replication and clonal amplification. The principal types of
vectors that are used are plasmid, cosmid (hybrid plasmid cloning vector
containing the Iambda cos site), Iambda bacteriophage, bacteriophage (Pl)
and yeast artificial chromosomes (YACs). The limiting factors involved in
library construction are basically related to the biological characteristics of
these vectors.
This chapter will review the main features of genomic libraries, as weil as
the basic principles essential to the efficient use of libraries: library complexity, redundancy, chimerism and unclonable elements. It will also review
some of the uses of genomic libraries, emphasizing how the anticipated use
of the library affects the design of its construction and the selection of an
appropriate host and vector. Basicfeatures of the methods used to construct
genomic libraries, such as partial digestion, first and second strand synthesis, size selection, and packaging, will also be discussed in this chapter. The
features and methods of cDNA libraries will be described in Chap. 18.
Luiz F. Onuchic, Johns Hopkins University, School ofMedicine, Division ofNephrology,
720 Rutland Avenue, Ross 970, Balitmore, Maryland, USA, Correspondence to Gregory G.
Germino, Johns Hopkins University, School of Medicine, Division of Nephrology, 720
Rutland Avenue, Ross 970, BalitmoreMarylandUSA (phone +01-410-614-1650;fax +01410-955-0485; e-mail ggermino@welchlink.welch.jhu.edu)
Genomic libraries
LUIZ F. ONUCHIC AND GREGORY G. GERMINO
lntroduction
Library construction and screening are essential techniques that permit the
isolation and manipulation of a DNA sequence of interest. A library of
clones, whether derived from genomic DNA or mRNA, is a set of molecules
that, ideally, faithfully represents the entire population of molecules that are
in the source material from which the librarywas made. DNA fragments and
DNA copies of mRNA (complementary DNA, also called cDNA), however,
cannot propagate without assistance. Therefore, these molecules are cloned
into biological vectors which provide the necessary cellular machinery required for DNA replication and clonal amplification. The principal types of
vectors that are used are plasmid, cosmid (hybrid plasmid cloning vector
containing the Iambda cos site), Iambda bacteriophage, bacteriophage (Pl)
and yeast artificial chromosomes (YACs). The limiting factors involved in
library construction are basically related to the biological characteristics of
these vectors.
This chapter will review the main features of genomic libraries, as weil as
the basic principles essential to the efficient use of libraries: library complexity, redundancy, chimerism and unclonable elements. It will also review
some of the uses of genomic libraries, emphasizing how the anticipated use
of the library affects the design of its construction and the selection of an
appropriate host and vector. Basicfeatures of the methods used to construct
genomic libraries, such as partial digestion, first and second strand synthesis, size selection, and packaging, will also be discussed in this chapter. The
features and methods of cDNA libraries will be described in Chap. 18.
Luiz F. Onuchic, Johns Hopkins University, School ofMedicine, Division ofNephrology,
720 Rutland Avenue, Ross 970, Balitmore, Maryland, USA, Correspondence to Gregory G.
Germino, Johns Hopkins University, School of Medicine, Division of Nephrology, 720
Rutland Avenue, Ross 970, BalitmoreMarylandUSA (phone +01-410-614-1650;fax +01410-955-0485; e-mail ggermino@welchlink.welch.jhu.edu)