Blunt-end ligation of a "filled-in" HindIII, Sal I, Ava I or Bcl I restriction site with a DNA fragment having A, G, C, or T as the terminal 3' nucleotide regenerates the corresponding restriction site. A combination of this property with the action of BAL 31 nuclease which progressively removes base-pairs from the ends of linear DNA, can generate deletions extending to desired pre-selected nuc...

DNA generated by the polymerase chain reaction (PCR) (1) containing terminal restriction endonuclease recognition sites to permit cloning usually relies on the use of unphosphorylated primers incorporating a restriction endonuclease recognition site of choice plus 3 —4 extra 5' bases flanking that site. Various sites (Notl, Xhol and Xbal (2), for example) incorporated into the termini of PCR pr...

b ackground: due to the lack of a suitable and economic test for the analysis of the polymorphism at codon 167, we developed a new pcr-rflp technique, based on a modified forward primer (ut- hc167 mf-primer), to identify simultaneously the snps at codons 167 and 200 of isotype 1 β-tubu- lin gene of haemonchus contortus . m ethods: there already are several safe and easy methods for identificati...

The restriction endonuclease from E. coli B is both an endonuclease and a DNA methylase. Both activities either require or are stimulated by Mg(+2), adenosine triphosphate, and S-adenosyl-L-methionine. The particular activity which the enzyme exhibits depends upon the nature of the SB sites, the genetic sites that identify substrate DNA. Enzymatic treatment of DNA that has an unmodified, wild-t...

A novel, site-specific, DNA backbone S-modification (phosphorothioation) has been discovered, but its in vivo function(s) have remained obscure. Here, we report that the enteropathogenic Salmonella enterica serovar Cerro 87, which possesses S-modified DNA, restricts DNA isolated from Escherichia coli, while protecting its own DNA by site-specific phosphorothioation. A cloned 15-kb gene cluster ...