Extremely low frequency weak magnetic fields enhance resistance of NN tobacco plants to tobacco mosaic virus and elicit stress-related biochemical activities.

Increasing evidence has accumulated concerning the biological effects of extremely low frequency magnetic fields (ELF-MFs) in different plant models. In the present study, effects of ELF-MFs in tobacco plants reacting to tobacco mosaic virus (TMV) with a hypersensitive response (HR) were evaluated. Plants were exposed for 8 or 24 h (either before or after TMV inoculation) to a static MF, at either -17 or 13 microT, combined with a 10 Hz sinusoidal MF with different intensities (25.6 or 28.9 microT). The working variables were the area and number of hypersensitive lesions in leaves. Following ELF-MFs exposure, an increased resistance was detected, particularly after an 8-h treatment, as shown by the decrease in lesion area and number. Moreover, two enzyme activities involved in resistance mechanisms were analyzed: ornithine decarboxylase (ODC) and phenylalanine ammonia-lyase (PAL). Uninoculated leaves previously exposed to ELF-MFs in general showed a significant increase relative to controls in ODC and PAL activities, in particular for 13 microT static MF plus 28.9 microT, 10 Hz sinusoidal MF (24 h) treatment. In conclusion, ELF-MFs seem to influence the HR of tobacco to TMV, as shown by the increased resistance and changes in ODC and PAL activities, indicating the reliability of the present plant model in the study of bioelectromagnetic interactions.

Effects of homeopathic arsenic on tobacco plant resistance to tobacco mosaic virus. Theoretical suggestions about system variability, based on a large experimental data set.

CONTEXT: This research aimed at verifying the efficacy of homeopathic treatments by plant-based bioassays, which may be suitable for basic research, because they lack placebo effects and provide large datasets for statistical analyses. OBJECTIVE: To evaluate the effects of homeopathic treatments of arsenic trioxide (As2O3) on tobacco plants subjected to tobacco mosaic virus (TMV) inoculation as biotic stress. DESIGN: Blind, randomized experiment using tobacco leaf disks. MATERIALS AND METHODS: Tobacco plants (Nicotiana tabacum L. cultivar Samsun) carrying the TMV resistance gene N. TMV inoculated leaf disks were floated for 3 days in the following: Distilled water (control). H2O 5 and 45 decimal and centesimal potencies. As2O3 5 and 45 decimal and centesimal potencies. The main outcome measures is the number of hypersensitive lesions observed in a leaf disk. RESULTS: Homeopathic treatments of arsenic induce two effects on the plant: (i) increased resistance to TMV; (ii) decrease variability between experiments (system variability). CONCLUSIONS: In this experimental model two actions of homeopathic treatment were detected: decrease in system variability and enhancement of the natural tendency of the system towards an 'equilibrium point'.

Effects of homeopathic arsenic on tobacco plant resistence to tobacco mosaic virus. Theoretical suggestions about system variability, basead on a large experimental data set

This research aimed at verifying the efficacy of homeopathic treatments by plant-based bioassays, which may be suitable for basic research, because they lack placebo effects and provide large datasets for statistical analyses. (AU)

Inhibition of proteasome activity strongly affects kiwifruit pollen germination. Involvement of the ubiquitin/proteasome pathway as a major regulator.

The 26S proteasome is a multicatalytic complex that acts as primary protease of the ubiquitin-mediated proteolytic pathway in eukaryotes. We provide here the first evidence that the proteasome plays a key role in regulating pollen tube growth. Immunoblotting experiments revealed the presence of high levels of free ubiquitin and ubiquitin conjugates in rehydrated and germinating pollen of kiwifruit [Actinidia deliciosa var. deliciosa (A. Chev) C. F. Liang et A. R. Ferguson]. Proteasome activity, assayed fluorometrically, accompanied the progression of germination. Specific inhibitors of proteasome function such as benzyloxycarbonyl-leucinyl-leucinyl-leucinal (MG-132), clasto-lactacystin beta-lactone, and epoxomicin significantly decreased tube growth or altered tube morphology. High-molecular mass, ubiquitinated proteins accumulated in MG-132- and beta-lactone-treated pollen, indicating that proteasome function was effectively impaired. The inhibitors were also able to decrease in vitro proteasome activity in pollen extracts. Because MG-132 can inhibit calpains, as well as the proteasome, trans-epoxy succinyl-L-leucylamido-(4-guanidino) butane (E-64), an inhibitor of cysteine proteases, was investigated. Some reduction in tube growth rate was observed, but only at 80 microM E-64, and no abnormal tubes were produced. Furthermore, no inhibition of tube growth was observed when another inhibitor of cysteine proteases, leupeptin, or inhibitors of serine and aspartic proteases (phenylmethylsulfonyl fluoride and pepstatin) were used. Our results indicate that protein turnover during tube organization and elongation in kiwifruit pollen is important, and our results also implicate the ubiquitin/26S proteasome as the major proteolytic pathway involved.

[The use of echography and US-guided percutaneous puncture in addition to mammography for the detection of malignant breast tumors]. / L'impiego dell'ecografia e della puntura percutanea ecoguidata in aggiunta alla mammografia per l'individuazione dei tumori maligni della mammella.

At present, mammography is the most effective means to detect breast cancers, especially in the early stages. However, it lacks sensitivity and specificity in women with dense breasts. Moreover, indeterminate lesions are often seen on mammograms, which should undergo further examination before surgery. Due to recent improvement in the technique--i.e., the use of high-resolution 10-MHz transducers--US can now detect also nonpalpable breast lesions, about 1 cm phi. Fine-needle biopsy (FNB) under US guidance, which is complementary to US, allows a correct diagnosis of malignancy in a high number of cases. A total of 1821 women with indeterminate lesions at mammography underwent US, and 491 of them underwent US-guided FNB, in the Leno Hospital (Brescia, Italy), in the period 1988-90. Thirty-one breast cancers which had been missed at mammography and clinical examination were found. Three cases were carcinomas in situ, 23 invasive cancers were classified as pathological stage T1, and 15 cases had no axillary lymph node involvement. The routine use of US and FNB in addition to mammography when indeterminate lesions are seen on mammograms and in women with dense breasts may significantly reduce the number of both false-negative cases at mammography and unnecessary biopsies.