Terminal restriction fragment length polymorphism (T-RFLP) analysis is a widespread technique for rapidly fingerprinting microbial communities. Users of T-RFLP frequently overlook the resolving power of well-chosen restriction endonucleases and often fail to report how they chose their enzymes. REPK (Restriction Endonuclease Picker) assists in the rational choice of restriction endonucleases fo...

Replicating molecules of the min-ColE1 plasmid pVH51 have been examined by electron microscopy after cleavage with the restriction endonuclease EcoRI. Replication apparently starts at a unique site indistinguishable from the origin of replication used by the parental plasmid ColE1. In contrast to ColE1, the structure of the majority of the replication intermediates was consistent with a bidirec...

Visualization of site-specific labels in long linear or circular DNA allows unambiguous identification of various local DNA structures. Here we describe a novel and efficient approach to site-specific DNA labeling. The restriction enzyme SfiI binds to DNA but leaves it intact in the presence of calcium and therefore may serve as a protein label of 13 bp recognition sites. Since SfiI requires si...

This study examined minisatellite DNA variation in three groups of Auckland Island teals from three locations (Boat Bay, Nellie Spit and East Coast). To determine whether teals showed high levels of natal philopatry, we were asked to test two hypotheses: 1) birds within each group are more closely related to each than to those in other groups; and 2) birds from nearby sites, Boat Bay and Nellie...

Genomic DNAs of 14 strains from seven species of the spirochete Leptospira were resistant to cleavage by the restriction endonuclease RsaI (5'-GTAC). A modified base comigrating with m4C was detected by chromatography. Genomic DNAs from other spirochetes, Borrelia group VS461, and Serpulina strains were not resistant to RsaI digestion. Modification at 5'-GTAm4C may occur in most or all strains ...

Since the 1960s, biological macromolecules have occupied an increasingly important role in evolutionary and systematic studies. These biological macromolecules, used as sources of molecular characteristics, are proteins and various types of DNA such as a nuclear genome, nuclear ribosomal DNA, mitochondrial genome, and chloroplast genome. Electrophoresis and immunological techniques are used for...

We describe an investigative laboratory module designed to give college undergraduates strong practical and theoretical experience with recombinant DNA methods within 3 weeks. After deducing restriction enzyme maps for two different plasmids, students ligate the plasmids together in the same reaction, transform E. coli with this mixture of ligated DNA, and plate the cells on media that specific...

Restriction-modification (RM) systems comprise two opposing enzymatic activities: a restriction endonuclease, that targets specific DNA sequences and performs endonucleolytic cleavage, and a modification methyltransferase that renders these sequences resistant to cleavage. Studies on molecular genetics and biochemistry of RM systems have been carried out over the past four decades, laying found...

A restriction (R) endonuclease recognizes a specific DNA sequence and introduces a double-strand break (Fig. 1A). A cognate modification (M) enzyme methylates the same sequence and thereby protects it from cleavage. Together, these two enzymes form a restriction-modification system. The genes encoding the restriction endonuclease and the cognate modification enzyme are often tightly linked and ...

Type II restriction endonucleases protect bacteria against phage infections by cleaving recognition sites on foreign double-stranded DNA (dsDNA) with extraordinary specificity. This capability arises primarily from large conformational changes in enzyme and/or DNA upon target sequence recognition. In order to elucidate the connection between the mechanics and the chemistry of DNA recognition an...