Bacteriophage phiX174 cannot grow in a temperature-sensitive dnaC mutant of Escherichia coli C at the nonpermissive temperature. The inability to grow is the result of inhibition of virus DNA synthesis. Parental replicative form synthesis is not temperature sensitive. Single-stranded virus DNA continues to be synthesized for at least 45 min after shifting to the nonpermissive temperature late i...

Accurate magnification calibration for transmission electron microscopy is best achieved with the use of appropriate standards and an objective calibration technique. We have developed a reliable method for calibrating the magnification of images from frozen-hydrated specimens. Invariant features in radial density plots of a standard are compared with the corresponding features in a "defocused"...

Protein requirements for conversion of phiX174 single-stranded DNA to a double-stranded replicative form with a small gap (RF II) have been determined by resolution and reconstitution of the multienzyme system from extracts of gently lysed Escherichia coli. Assays depended on: (a) complementation of extracts of thermosensitive mutants and (b) fractionation of extracts of wild type cells to divi...

Quantitative real-time PCR has become a popular method to analyze and quantify changes in the copy number of mitochondrial DNA (mtDNA), and nuclear DNA (nDNA) is often used as an endogenous reference for mtDNA abundance. In our experience, using nDNA as a reference is problematic, due to differences in the extraction efficiency of nDNA and mtDNA and variation in the ploidy of experimental sampl...

Those of your readers who are interested in anticonvulsant-drug analyses will be familiar with the drugs ethotoin (Peganone#{174}, 3-ethyl-5-phenylhydantoin) and mephenytoin (Mesantoin#{174}, 5-ethyl-3methyl-5-phenylhydantoin). They will also be familiar with the name Nirvanol#{174}. Unfortunately, a dreadful state of confusion exists among various authorities as to whether Nirvanol is ethotoin...

After characterization of the porin OmpF and selection of molecular structures responsible for leukocyte activation by using computer-assisted epitope analysis, the analogs OmpF (153-174) (containing amino acids 153 to 174), OmpF (157-174), and OmpF (275-285) were synthesized and tested. Like the native protein, the segments were mitogenic for BALB/c splenocytes and induced B lymphocyte differe...

HIV-1 Nef modulates disease progression through interactions with over 30 host proteins. Individual chains fold into membrane-interacting N-terminal and C-terminal core (Nef(core)) domains respectively. Nef exists as small oligomers near membranes and associates into higher oligomers such as tetramers or hexadecamers in the cytoplasm. Earlier structures of the Nef(core) in apo and complexed for...

The ability for a virus to expand its host range is dependent upon a successful mode of viral entry. As such, the host range of the well-studied PhiX174 bacteriophage is dictated by the presence of a particular lipopolysaccharide (LPS) on the bacterial surface. The mutant PhiX174 strain JACS-K, unlike its ancestor, is capable of infecting both its native host Escherichia coli C and E. coli K-12...

A histidine-tagged G protein of bacteriophage phi X174 (HisG) bound strongly with lipopolysaccharide (LPS) of Escherichia coli C, one of a phi X174-sensitive Ra strain. The dissociation constant, Kd, was measured to be 0.16 +/- 0.04 microM by fluorometric titration. HisG showed slightly less affinity to LPSs of the insensitive Rc and Rd 2 strains having shorter R-core polysaccharide sequences t...