Nonthermal control of Escherichia coli growth using extremely low frequency electromagnetic (ELF-EM) waves.

BACKGROUND: Escherichia coli (E. coli) bacteria normally live in the intestines of people and animals. Most E. coli are harmless and the treatment of the infection could be achieved by using antibiotics, however the effectiveness is still debatable and needs more investigation. OBJECTIVE: Researching the inhibition resonance frequency of square amplitude modulating waves (QAMW) that can inhibit the growth activity of E. coli and its ability to make division. METHODS: A range of different extremely low frequencies of square amplitude modulated waves (QAMW) from 0.1 to 1.0 Hz from two generators with a constant carrier frequency of 10 MHz, amplitude of 10 Vpp, modulating depth ± 2 Vpp and constant field strength 200 V/m were used to treat E. coli cells at 37 °C. RESULTS: The exposure of E. coli to 0.3 Hz QAMW for 90 min was the most inhibited frequency where the bacterial growth inhibited by 42.3%. Furthermore, a significant increase in antibiotic susceptibility to protein and cell wall inhibitors was investigated. Also, results of the chromosomal DNA sequences, dielectric relaxation and TEM indicated highly significant molecular and morphological changes after the exposure. CONCLUSIONS: We concluded that the exposure of E. coli to QAMW at the inhibiting frequency interfered with the bioelectric signals generated from the bacteria during the cell division and changed the cellular activity and DNA sequences, and these changes lead to a significant inhibition of the bacterial growth. This is a new promising technique that aids to avoid the repetitive use of antibiotics against the bacterial pathogens.

Molecular characterization of the pathogenic plant fungus Rhizoctonia solani (Ceratobasidiaceae) isolated from Egypt based on protein and PCR-RAPD profiles.

Twenty-one isolates of Rhizoctonia solani were categorized into three anastomosis groups consisting of AG-4-HG-I (eight isolates), AG-2-2 (nine isolates) and AG-5 (four isolates). Their pathogenic capacities were tested on cotton cultivar Giza 86. Pre-emergence damping-off varied in response to the different isolates; however, the differences were not significant. Soluble proteins of the fungal isolates were electrophoresed using SDS-PAGE and gel electrophoreses. A dendrogram of the protein banding patterns by the UPGMA of arithmetic means placed the fungal isolates into distinct groups. There was no evidence of a relationship between protein dendrogram, anastomosis grouping or level of virulence or geographic origin. The dendrogram generated from these isolates based on PCR analysis with five RAPD-PCR primers showed high levels of genetic similarity among the isolates from the same geographical locations. There was partially relationship between the genetic similarity and AGs or level of virulence or geographic origin based on RAPD dendrogram. These results demonstrate that RAPD technique is a useful tool in determining the genetic characterization among isolates of R. solani.

Molecular mapping of the novel powdery mildew resistance gene Pm36 introgressed from Triticum turgidum var. dicoccoides in durum wheat.

Powdery mildew, caused by Blumeria graminis f.sp. tritici, is one of the most important wheat diseases in many regions of the world. Triticum turgidum var. dicoccoides (2n=4x=AABB), the progenitor of cultivated wheats, shows particular promises as a donor of useful genetic variation for several traits, including disease resistances. The wild emmer accession MG29896, resistant to powdery mildew, was backcrossed to the susceptible durum wheat cultivar Latino, and a set of backcross inbred lines (BC(5)F(5)) was produced. Genetic analysis of F(3) populations from two resistant introgression lines (5BIL-29 x Latino and 5BIL-42 x Latino) indicated that the powdery mildew resistance is controlled by a single dominant gene. Molecular markers and the bulked segregant analysis were used to characterize and map the powdery mildew resistance. Five AFLP markers (XP43M32((250)), XP46M31((410)), XP41M37((100)), XP41M39((250)), XP39M32((120))), three genomic SSR markers (Xcfd07, Xwmc75, Xgwm408) and one EST-derived SSR marker (BJ261635) were found to be linked to the resistance gene in 5BIL-29 and only the BJ261635 marker in 5BIL-42. By means of Chinese Spring nullisomic-tetrasomic, ditelosomic and deletion lines, the polymorphic markers and the resistance gene were assigned to chromosome bin 5BL6-0.29-0.76. These results indicated that the two lines had the same resistance gene and that the introgressed dicoccoides chromosome segment was longer (35.5 cM) in 5BIL-29 than that introgressed in 5BIL-42 (less than 1.5 cM). As no powdery mildew resistance gene has been reported on chromosome arm 5BL, the novel resistance gene derived from var. dicoccoides was designated Pm36. The 244 bp allele of BJ261635 in 5BIL-42 can be used for marker-assisted selection during the wheat resistance breeding process for facilitating gene pyramiding.