Escherichia coli exonuclease III enhances long PCR amplification of damaged DNA templates

Recent development of the long PCR technology has provided an invaluable tool in many areas of molecular biology. However, long PCR amplification fails whenever the DNA template is imperfectly preserved. We report that Escherichia coli exonuclease III, a major repair enzyme in bacteria, strikingly improves the long PCR amplification of damaged DNA templates. Escherichia coli exonuclease III permitted or improved long PCR amplification with DNA samples submitted to different in vitro treatments known to induce DNA strand breaks and/or apurinic/apyrimidinic (AP) sites, including high temperature (99°C), depurination at low pH and near-UV radiation. Exonuclease III also permitted or improved amplification with DNA samples that had been isolated several years ago by the phenol/chloroform method. Amelioration of long PCR amplification was achieved for PCR products ranging in size from 5 to 15.4 kb and with DNA target sequences located either within mitochondrial DNA or the nuclear genome. Exonuclease III increased the amplification of damaged templates using either rTth DNA polymerase alone or rTth plus Vent DNA polymerases or Taq plus Pwo DNA polymerases. However, exonuclease III could not improve PCR amplification from extensively damaged DNA samples. In conclusion, supplementation of long PCR mixes with E.coli exonuclease III may represent a major technical advance whenever DNA samples have been partly damaged during isolation or subsequent storage.     

Onychomycosis in Tehran,Iran: Prevailing fungi and treatment with itraconazole

A total of 187 Patients with suspected onychomycosis were examined for causative fungal agents between 1996 and 1997. Laboratory examination confirmed onychomycosis in 115 patients, of which 97 cases were presented with positive microscopic and cultural examinations, and they were selected for itraconazole pulse therapy. From an etiological point of view, 48.4% of the nail infections, mainly toenail infections, were caused by dermatophytes, 43.3% were infected with Candida spp, specially infected fingernails, and 8.2% by non-dermatophytic molds. Trichophyton mentagrophytes var. interdigital and T. violaceum were the most prevalent species. Candida albicans and C. parapsilosis were the predominant species of the Genus Candida. Scopolariopsis brevicaulis was the most common non-dermatophyte molds observed. Female affected more frequently than male and in both sexes, those who were 30–49 years old, more infected. Toenails were affected more frequently than fingernails. In this study, itraconazole pulse therapy (400 mg daily) gave during the first week of per month for 3 months. The study included 51 patients with toenail onychomychosis (group 1) and 46 patients with fingernail infections (group 2). Patients were followed up for 9 months after the last treatment. Clinical response rates were 83% in the group 1, 95% in the group 2 at month 12; the corresponding mycological cure rates were 71 and 87%, respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Agglutinin of Common Nettle (Urtica dioica L.) Plant Effects on Gene Expression Related to Apoptosis of Human Acute Myeloid Leukemia Cell Line

Biochemical Genetics - Treatment of acute myeloid leukemia (AML) requires new drugs as result of a rise in new cases and high disease relapse. Plant lectins with the ability to bind carbohydrates...     

DNA binding, DNA cleavage, and cytotoxicity studies of two new copper (II) complexes

The DNA binding behavior of [Cu(phen)(phen-dione)Cl]Cl (1) and [Cu(bpy)(phen-dione)Cl]Cl (2) was studied with a series of techniques including UV-vis absorption, circular dichroism spectroscopy, and viscometric methods. Cytotoxicity effect and DNA unwinding properties were also investigated. The results indicate that the Cu(II) complexes interact with calf-thymus DNA by both partially intercalative and hydrogen binding. These findings have been further substantiated by the determination of intrinsic binding constants spectrophotometrically, 12.5?×?10(5) and 5?×?10(5) for 1 and 2, respectively. Our findings suggest that the type of ligands and structure of complexes have marked effect on the binding affinity of complexes involving CT-DNA. Circular dichroism results show that complex 1 causes considerable increase in base stacking of DNA, whereas 2 decreases the base stacking, which is related to more extended aromatic area of 1,10-phenanthroline in 1 rather than bipyridine in 2. Slow decrease in DNA viscosity indicates partially intercalative binding in addition to hydrogen binding on the surface of DNA. The second binding mode was also confirmed by additional tests: interaction in denaturation condition and acidic pH. Also, these new complexes induced cleavage in pUC18 plasmid DNA as indicated in gel electrophoresis and showed excellent antitumor activity against K562 (human chronic myeloid leukemia) cells.