The ability of Legionella pneumophila to act as a recipient of IncP and IncQ plasmids in matings with Escherichia coli varies widely from strain to strain. We found that the low efficiency of mating of the Philadelphia-1 strain is due to a type II restriction-modification system, and we isolated and characterized a Philadelphia-1 mutant that lacks the restriction enzyme activity.

In this paper, we describe a 3.8-kb molecular construct that we have used to disrupt yeast genes. The construct consists of a functional yeast URA3 gene flanked by 1.1-kb direct repeats of a bacterial sequence. It is straightforward to insert the 3.8-kb segment into a cloned target gene of interest and then introduce the resulting disruption into the yeast genome by integrative transformation. ...

Plasmids 1.6, 2.8, or greater than 40 megadaltons in size were found in one urethral and nine throat strains of meningococci. Throat meningococci are known to be heterogeneous in their aminopeptidase profiles. Their unexpected content of plasmids is further evidence of their difference from classic systemic strains. Although the 2.8 megadalton plasmid has some resemblance to the well known 2.6 ...

DNA helicases play essential roles in many cellular processes. The currently available techniques to generate substrates for helicase assays are fairly complicated and need some expertise not available in all laboratories. Here, a PCR-based method to generate a substrate for a helicase assay is described, and its application for several archaeal, bacterial and viral enzymes is demonstrated.

Certain type II restriction modification gene systems can kill host cells when these gene systems are eliminated from the host cells. Such ability to cause postsegregational killing of host cells is the feature of bacterial addiction modules, each of which consists of toxin and antitoxin genes. With these addiction modules, the differential stability of toxin and antitoxin molecules in cells pl...

Type II restriction endonucleases (REases) are deoxyribonucleases that cleave DNA sequences with remarkable specificity. Type II REases are highly divergent in sequence as well as in topology, i.e. the connectivity of secondary structure elements. A widely held assumption is that a structural core of five beta-strands flanked by two alpha-helices is common to these enzymes. We introduce a syste...

Pocillopora damicornis (Linnaeus, 1758; Scleractinia, Pocilloporidae) has recently been found to comprise at least five distinct genetic lineages in Eastern Australia, some of which likely represent cryptic species. Due to similar and plastic gross morphology of these lineages, field identification is often difficult. Here we present a quick, cost effective genetic assay as well as three novel ...

Herein we show that two isothermal amplification strategies, rolling circle amplification and junction probe strategy, can be used in tandem in the same tube under isothermal conditions to detect HPV16 in clinical cervical swabs. It was discovered that the prior treatment of the clinical sample with a cocktail of restriction endonucleases (REAses) to digest the genomic DNA facilitated the isoth...

Single-stranded regions (gaps) in nucleosomal DNA interfere with action of the RSC chromatin-remodeling complex, monitored by exposure of restriction endonuclease cutting sites. Single-strand breaks (nicks) in the DNA, by contrast, have no effect. Gaps on one side of the cutting site are inhibitory, but gaps on the other side are not. A gap >100 bp from the cutting site is as effective as a gap...

We have synthesized a series of oligonucleotides containing the EcoRI (GAATTC) or EcoRV (GATATC) recognition site within which or adjacent to which thymidine was substituted by uridine or derivatives of uridine. The effects of these substitutions on the rate of the EcoRI and EcoRV catalyzed cleavage reaction were investigated. Our results show that most of the substitutions within the site are ...