ABSTRACT
Isolates of Bipolaris sorokiniana were analyzed by random-amplified polymorphic DNA (RAPD) techniques to determine the amount of intraspecific genetic variability and to study host-pathogen interactions. Ten isolates originated from different regions of Brazil were examined. Plants of the wheat cultivars BR8, BH1146 (original host) and IAC-5 Maringá, classified as resistant, moderately resistant or susceptible to B. sorokiniana, respectively, were inoculated with these 10 isolates. Twenty-seven isolates were recovered from these cultivars and were analyzed by RAPD assay and compared to the RAPD of the original 10 isolates. According to the RAPD profiles there was a high level of genetic variability among the isolates. We detected 69 polymorphic fragments, ranging from 1.6 to 0.54 kb, in the original 10 isolates; 57 fragments with sizes between 1.98 and 0.38 kb from the isolates recovered from BH1146; 47 polymorphic bands, ranging from 1.96-0.54 kb, were detected in the isolates from BR8 and 32 fragments between 1.98 and 0.42 kb in isolates were recovered from IAC-5 Maringá. The number of polymorphic fragments varied, even for the same isolate, when the isolates were recovered from different cultivar hosts.
Subject(s)
Ascomycota/genetics , DNA, Fungal/analysis , Genetic Variation/genetics , Triticum/microbiology , Ascomycota/isolation & purification , Brazil , Host-Parasite Interactions/genetics , Polymorphism, Genetic , Random Amplified Polymorphic DNA TechniqueABSTRACT
This study evaluated the sensitivity of serological and direct methods for the diagnosis of Helicobacter pylori infection in 127 patients with gastric carcinoma and in 127 controls without this disease, matched for age and sex. Antral and oxyntic mucosal specimens were obtained from all patients, at operation in patients with gastric carcinoma and at endoscopy from controls. The urease test, microscopy of stained smears and culture for H. pylori were performed on all specimens. Sera from all patients were tested for antibodies to H. pylori by a highly sensitive and specific IgG-ELISA. Culture, urease test, stained smear and ELISA were significantly less sensitive in the patients with gastric carcinoma than in control subjects. However, the combination of several methods improved the diagnosis of H. pylori infection in the gastric carcinoma group. Infection was significantly more frequent in the gastric carcinoma patients than in the controls. H. pylori infection was associated with an increased risk of developing gastric carcinoma.
