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Background
Emerging whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops throughout the world, particularly in tropical and sub-tropical regions. Mutation, pseudorecombination and recombination are driving forces for the emergence and evolution of new crop-infecting begomoviruses. Leaf curl disease of field grown radish plants was noticed in Varanasi and Pataudi region of northern India. We have identified and characterized two distinct monopartite begomoviruses and associated beta satellite DNA causing leaf curl disease of radish (Raphanus sativus) in India.Results
We demonstrate that RaLCD is caused by a complex of two Old World begomoviruses and their associated betasatellites. Radish leaf curl virus-Varanasi is identified as a new recombinant species, Radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-[Bangladesh:2] (Accession number AF188481) while the virus causing radish leaf curl disease-Pataudi is an isolate of Croton yellow vein mosaic virus-[India] (CYVMV-IN) (Accession number AJ507777) sharing 95.8% nucleotide identity. Further, RDP analysis revealed that the RaLCV has a hybrid genome, a putative recombinant between Euphorbia leaf curl virus and Papaya leaf curl virus. Cloned DNA of either RaLCV or CYVMV induced mild leaf curl symptoms in radish plants. However, when these clones (RaLCV or CYVMV) were individually co-inoculated with their associated cloned DNA betasatellite, symptom severity and viral DNA levels were increased in radish plants and induced typical RaLCD symptoms. To further extend these studies, we carried out an investigation of the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses (Tomato leaf curl Gujarat virus and Tomato leaf curl New Delhi virus). Both of the tomato-infecting begomoviruses showed a contrasting and differential interaction with DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites.Conclusion
This is the first report and experimental demonstration of Koch's postulate for begomoviruses associated with radish leaf curl disease. Further observations also provide direct evidence of lateral movement of weed infecting begomovirus in the cultivated crops and the present study also suggests that the exchange of betasatellites with other begomoviruses would create a new disease complex posing a serious threat to crop production. 相似文献Introduction
Immediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience. The present study explores whether the evaluation of stimulus salience in the acoustic communication of emotions is specifically human or has precursors in mammals. We created different pre-experiences by habituating bats (Megaderma lyra) to stimuli based on aggression, and response, calls from high or low intensity level agonistic interactions, respectively. Then we presented a test stimulus of opposite affect intensity of the same call type. We compared the modulation of response behaviour by affect intensity between the reciprocal experiments.Results
For aggression call stimuli, the bats responded to the dishabituation stimuli independent of affect intensity, emphasising the attention-grabbing function of this call type. For response call stimuli, the bats responded to a high affect intensity test stimulus after experiencing stimuli of low affect intensity, but transferred habituation to a low affect intensity test stimulus after experiencing stimuli of high affect intensity. This transfer of habituation was not due to over-habituation as the bats responded to a frequency-shifted control stimulus. A direct comparison confirmed the asymmetric response behaviour in the reciprocal experiments.Conclusions
Thus, the present study provides not only evidence for a discrimination of affect intensity, but also for an evaluation of stimulus salience, suggesting that basic assessment mechanisms involved in the perception of emotion are an ancestral trait in mammals.Several species of eukaryotic organisms living in the high mountain areas of Armenia with naturally occurring levels of radiation have high adaptive responses to radiation. We speculate on the role of the gastrointestinal microbiota in this protection against radiation. Therefore, seventeen microorganisms with high antagonistic activities against several multi-drug-resistant pathogens were isolated from the human and animal gut microbiota, as well as from traditional Armenian fermented products. These strains were tested in vivo on Wistar rats to determine their ability to protect the eukaryotic host against radiation damages. The efficiency of the probiotics’ application and the dependence on pre- and post-radiation nutrition of rats were described. The effects of Lactobacillus rhamnosus Vahe, isolated from a healthy breastfed infant, and Lactobacillus delbrueckii IAHAHI, isolated from the fermented dairy product matsuni, on the survival of irradiated rats, and their blood leucocyte and glucose levels, were considered to be the most promising, based on this study’s results.
相似文献The effects of 50–150 gray electron-beam irradiation on the biofilm-formation ability and cell surface hydrophobicity of the commercial strain, Lactobacillus acidophilus DDS®-1, from Lacto-G (a marketed synbiotic formulation) and the putative probiotic, L. rhamnosus Vahe, were evaluated. No significant changes in cell surface hydrophobicity were found after irradiation, while increases in biofilm-formation abilities were documented for both investigated microorganisms 0.22 ± 0.03 vs. 0.149 ± 0.02 (L. rhamnosus Vahe, 150 Gy) and 0.218 ± 0.021 vs. 0.17 ± 0.012 (L. acidophilus DDS®-1, 150 Gy). Given this, the use of electron-beam irradiation (50–100 Gy) for the treatment of L. rhamnosus Vahe and L. acidophilus DDS®-1 cells may be considered in product sterilization, quality improvement, and packaging practices.
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