Pest and disease management by red light.

Light is essential for plant life. It provides a source of energy through photosynthesis and regulates plant growth and development and other cellular processes, such as by controlling the endogenous circadian clock. Light intensity, quality, duration and timing are all important determinants of plant responses, especially to biotic stress. Red light can positively influence plant defence mechanisms against different pathogens, but the molecular mechanism behind this phenomenon is not fully understood. Therefore, we reviewed the impact of red light on plant biotic stress responses against viruses, bacteria, fungi and nematodes, with a focus on the physiological effects of red light treatment and hormonal crosstalk under biotic stress in plants. We found evidence suggesting that exposing plants to red light increases levels of salicylic acid (SA) and induces SA signalling mediating the production of reactive oxygen species, with substantial differences between species and plant organs. Such changes in SA levels could be vital for plants to survive infections. Therefore, the application of red light provides a multidimensional aspect to developing innovative and environmentally friendly approaches to plant and crop disease management.

[Composition and Density of Soil Fauna in the Region with Enhanced Radioactivity Level (Komi Republic, Vodnyi)].

Studies on the influence of high levels of radiation on soil fauna were carried out in 2012 in the territory formed as a result of the activity of the enterprise for extraction and production of radium from reservoir water and waste of uranium ore from 1931 to 1956. At present the local radioactive pollution in this area is caused by the presence of heavy natural radionuclides 226Ra, 238U and products of their disintegration in soils. The oppression of soil invertebrate.fauna in pine forests and meadows with high levels of radionuclides and heavy metals is revealed. Also shown is the decrease in the number and density of different taxonomic groups of invertebrates, reduction of the diversity and spectrum of trophic groups and vital forms in the area with a high content of radionuclides in soil. Our results are in agreement with the results obtained by the similar studies showing negative influence of high-level ionizing radiation on soil fauna.

Interactive effects of elevated ozone and UV-B radiation on soil nematode diversity.

Ultraviolet-B (UV-B) radiation and elevated tropospheric ozone may cause reductions in the productivity and quality of important agricultural crops. However, research regarding their interactive effect is still scarce, especially on the belowground processes. Using the open top chambers experimental setup, we monitored the response of soil nematodes to the elevated O3 and UV-B radiation individually as well as in combination. Our results indicated that elevated O3 and UV-B radiation have impact not only on the belowground biomass of plants, but also on the community structure and functional diversity of soil nematodes. The canonical correspondence analysis suggested that soil pH, shoot biomass and microbial biomass C and N were relevant parameters that influencing soil nematode distribution. The interactive effects of elevated O3 and UV-B radiation was only observed on the abundance of bacterivores. UV-B radiation significantly increased the abundance of total nematodes and bacterivores in comparison with the control at pod-filling stage of soybean. Following elevated O3, nematode diversity index decreased and dominance index increased relative to the control at pod-filling stage of soybean. Nematode functional diversity showed response to the effects of elevated O3 and UV-B radiation at pod-bearing stage. Higher enrichment index and lower structure index in the treatment with both elevated O3 and UV-B radiation indicated a stressed soil condition and degraded soil food web. However, the ratios of nematode trophic groups suggested that the negative effects of elevated O3 on soil food web may be weakened by the UV-B radiations.

Effect of moisture on efficiency of microwaves to control plant--parasitic nematodes in soil.

Laboratory studies were conducted to evaluate effect of microwave irradiation of sandy loam soil on thermal energy absorption and control of plant-parasitic nematodes when air dry soil layers were placed on top of less moist, moist, and wet soil layers. The soil was packed in 12 cm high and 10 cm dia columns to a bulk density of 1.4 g/cm3. Moisture contents of air dry, less moist, moist, and wet soils were 0.75, 4.50, 6.00, and 10.30%, respectively, on dry mass basis. The top air dry soil was 4.0 cm thick and the bottom layer was 8.0 cm thick. Temperature measurements and thermal radiation absorption data were monitored in both soil layers and showed that the use of a top dry soil both increased depth of penetration of microwave radiation and it provided insulation for better absorption of thermal energy in the lower layer of soil. An exposure of 65 seconds resulted in soil temperatures high enough to cause significant decrease in nematode population in soil infested with Rotylenchulus reniformis nematodes. No such effect was observed in combination where dry soil layer was placed over dry soil at the bottom. These results are helpful in sterilizing soil used for greenhouses and nurseries.

Pre-treatment with mild UV irradiation suppresses reproductive toxicity induced by subsequent cadmium exposure in nematodes.

In nematodes, 10 J/m(2)/min of UV irradiation induced a mild reproductive toxicity. Pre-treatment with UV irradiation at 10 J/m(2)/min suppressed the formation of reproductive defects, and activated a noticeable reduction of percentage of population with hsp-16.2::gfp expression, an obvious elevation of superoxide dismutase activities, and decrease of oxidative damage in 50 and 100 microM Cd exposed nematodes; however, pre-treatment with UV irradiation at 20 J/m(2)/min caused a significant decrease of brood sizes or increase of generation times in Cd-exposed nematodes. Pre-treatment with mild UV irradiation did not suppress the formation of reproductive defects in 150 microM Cd-exposed nematodes. Furthermore, the adaptive response to reproductive toxicity from Cd exposure was not observed in a reactive oxygen species sensitive mev-1(kn1) mutant. Therefore, pre-treatment with mild UV irradiation triggers the resistance to reproductive toxicity from Cd exposure by at least partially inducing adaptation to oxidative stress and through a mev-1-dependent pathway.

Viability of Pseudocapillaria tomentosa Eggs Exposed to Heat, Ultraviolet Light, Chlorine, Iodine, and Desiccation.

Pseudocapillaria tomentosa is an important pathogen in zebrafish facilities. We investigated heat, ultraviolet (UV) light, chlorine, iodine, and dessciation for killing the parasite's eggs. Eggs released with feces larvate in about 5-10 days, and treatments were evaluated by exposing fresh eggs and subsequently comparing larvation to untreated eggs as an indication of survival. Collectively, untreated eggs in all trials showed high levels of survival. Eggs were exposed to elevated temperatures (40°C, 45°C and 50°C) for 1, 8, or 24 h, which resulted in substantial reduction in viability of eggs. UV radiation was effective, with no larvation at 50-300 mWs/cm2 and <2% at 20 mWs/cm2. Three chlorine products (JT Baker, Clorox®, and Bi-Mart) were tested at 25, 50, 100, 500, and 3,000 ppm (pH 7.0-7.3) with 10 min exposure. All were effective at 500 or 1,000 ppm. There was variability between three products and trials at lower concentrations, but overall chlorine was not very effective at 25-100 ppm except for Bi-Mart brand at 100 ppm. Povidone-iodine was not effective at 25 or 50 ppm for 10 min, but was effective at 200 ppm for 1 h. Desiccation was effective, and no eggs larvated after 2 h drying.

Potential of microwaves to control plant-parasitic nematodes in soil.

Microwave radiation of 2450 MHz frequency was used to irradiate sandy loam soil placed in 12 cm high and 10 cm dia columns as a function of exposure times of 30, 45, 60, and 120 s. This was done to evaluate the effect of radiation on the highest soil temperature attained and subsequent temperature patterns in relation to time. Soil columns were packed to a field bulk density of approximately 1.4 g/cm3, and treatments consisted of moist soil, dry soil, and layers of moist and dry soil of varying thicknesses. Moisture contents of moist and dry soil were 10% and 2%, respectively, on a dry mass basis. An exposure time of 45 seconds was the most efficient in yielding soil temperatures high enough to kill plant-parasitic nematodes. Irradiation of soil infested with Rotylenchulus reniform nematodes for 45 seconds resulted in a 99% extermination of the organisms in all treatments. However, radiation proved to be most effective in nematode control with 6.0 cm dry soil placed over 6.0 cm moist soil.

Copper(II) oxide nanoparticles augment antifilarial activity of Albendazole: In vitro synergistic apoptotic impact against filarial parasite Setaria cervi.

Mass treatment of lymphatic filariasis with Albendazole (ABZ), a therapeutic benzimidazole, is fraught with serious limitations such as possible drug resistance and poor macrofilaricidal activity. Therefore, we need to develop new ABZ-based formulations to improve its antifilarial effectiveness. CuO nanoparticles were used as an adjuvant with ABZ to form ABZ-CuO nanocomposite, which was characterized by UV-vis spectroscopy, FT-IR, AFM and SEM. Antifilarial activity of nanocomposite was evaluated using relative motility assay and dye exclusion test in dark and under UV light. ROS generation, antioxidant levels, lipid peroxidation and DNA fragmentation in nanocomposite treated parasites were estimated. Biophysical techniques were employed to ascertain the mode of binding of nanocomposite to parasitic DNA. Nanocomposite increases parasite mortality as compared to ABZ in dark, and its antifilarial effect was increased further under UV light. Elevated ROS production and decline of parasitic-GST and GSH levels were observed in nanocomposite treated worms in dark, and these effects were pronounced further under UV light. Nanocomposite leads to higher DNA fragmentation as compared to ABZ alone. Further, we found that nanocomposite binds parasitic DNA in an intercalative manner where it generates ROS to induce DNA damage. Thus, oxidative stress production due to ROS generation and consequent DNA fragmentation leads to apoptosis in worms. This is the first report supporting CuO nanoparticles as a potential adjuvant with ABZ against filariasis along with enhanced antifilarial activity of nanocomposite under UV light. These findings, thus, indicate that development of ABZ-loaded nanoparticle compounds may serve as promising leads for filariasis treatment.

Chromosome rearrangements in Caenorhabditis elegans.

A method for selecting unlinked duplications of a part of the X chromosome of C. elegans is described. Five such duplications have been identified. One of them, Dp (X;V)1, is translocated to linkage group V, where it suppresses crossing over along the left half of linkage group V. Dp(X;V)1 homozygotes grow slowly and are sterile. The other four duplications are associated with chromosome fragments, as observed cytologically by fluorescence microscopy, and tend to be lost. Their frequency of loss is higher in strains homozygous for a mutation that promotes nondisjunction of X chromosomes. The recombination frequencies between two of these duplications and the X have been measured: the frequencies are at least 50 times less than for X-X recombination in the same region. The duplications may prove useful as balancers of recessive lethal mutations.

Crossover suppressors and balanced recessive lethals in Caenorhabditis elegans.

Two dominant suppressors of crossing over have been identified following X-ray treatment of the small nematode C. elegans. They suppress crossing over in linkage group II (LGII) about 100-fold and 50-fold and are both tightly linked to LGII markers. One, called C1, segregates independently of all other linkage groups and is homozygous fertile. The other is a translocation involving LGII and X. The translocation also suppresses crossing over along the right half of X and is homozygous lethal. C1 has been used as a balancer of LGII recessive lethal and sterile mutations induced by EMS. The frequencies of occurrence of lethals and steriles were approximately equal. Fourteen mutations were assigned to complementation groups and mapped. They tended to map in the same region where LGII visibles are clustered.

Effect of ultraviolet- and X-irradiation on embryogenesis of the free-living nematode, Rhabditidae tokai: hatchability, morphogenesis and life span.

Ultraviolet light (UV)- and X-irradiation reduced hatchability in a strain of free-living nematodes, Rhabditidae tokai. Sensitivities of eggs to UV and X-ray varied greatly depending on the lapse of time after oviposition. It was found that the eggs at 5 h after oviposition were most sensitive as compared with the eggs at other developmental stages. X-irradiation of the eggs resulted in significant life shortening of the worms after hatching, whereas UV-irradiation had no such life-shortening effect. Microscopic observations showed that the frequency of morphological anomalies in populations of unhatched embryos also varied depending on the stage at which UV- and X-irradiation was applied. These results suggest that X-irradiation but not UV-irradiation have a serious after-effect on worms hatched from treated eggs.

Age-related changes in the excision repair capacity of Turbatrix aceti.

Excision repair capacity was measured in the free-living nematode Turbatrix aceti, a model aging system. Excision repair was assessed by both repair synthesis activity and the actual removal of pyrimidine dimers from the genome. The young organisms removed lesions more rapidly and completely than the old for all fluences tested. Repair synthesis began and peaked earlier for young nematodes than old. The data consistently indicated a decline in DNA excision repair capacity with age in the nematode.

The effects of gamma radiation on the development of Heligmosomoides polygyrus bakeri in mice.

The development of a Heligmosomoides polygyrus bakeri (H. polygyrus) primary infection in its definitive host was severely effected by a wide range of gamma radiation doses (10-400 Gy). Male worms were more susceptible to gamma radiation than female worms. A dose of 400 Gy prevented the development of L3 larvae to mature female worms and 200 Gy abrogated the maturation of males. At 300 Gy, a dose known to stimulate high levels of protective immunity, male worms were unable to moult to the L4 stage and females failed to develop into morphologically normal adults. An experiment to select for a radiation resistant parasite line provided data on the cumulative effects of gamma rays on successive parasite generations. Parasite fitness data demonstrated that worm development, at the level of embryogenesis, was far more sensitive to radiation damage than either post embryonic development or adult worm fecundity. The parasite line died out on the 14th generation of selection after receiving an accumulated dose of 420 Gy. It is concluded that gamma radiation profoundly alters the developmental biology of H. polygyrus in a dose-dependent manner, with maximal sensitivity exhibited during embryogenesis.

Effect of dose-rate on the frequency of X-linked lethal mutation in the nematode Panagrellus redivivus.

A total X-ray dose of 50 Gy was applied to the nematode Panagrellus redivivus using dose-rates ranging from 0.23 Gy/min to 10.49 Gy/min, and the frequency of lethal X-chromosomes was determined. This frequency ranged from approximately 1.6% at the lower dose-rate to 4.3% at the highest dose-rate, indicating a dose-rate dependency of mutation frequency in the spermatogonia and oogonia of this organism.

Estimation of mutation rates induced by large doses of gamma, proton and neutron irradiation of the X-chromosome of the nematode Panagrellus redivivus.

The radiation-resistant free-living nematode Panagrellus redivivus was used to study mutation rates in oocytes, following gamma, proton and neutron irradiation in the dose range 45-225 grays. gamma-Radiation produced approximately 0.001 lethal X-chromosomes per gray over the range tested. Proton or neutron irradiation produced approximately 0.003 lethal X-chromosomes per gray at lower doses, with the mutation rate dropping to 0.001 lethal X-chromosome per gray at the higher doses. These results suggest a dose-dependent mutation-repair system. Cell lethality was also examined. gamma-Radiation produced the greatest amount of cell lethality at all doses, while neutron irradiation had no cell lethal effect at any of the doses examined.

Morphological variations in nematode parasites after a radioactive fall out: preliminary results.

Preliminary results from a survey of abomasal parasites of wild ruminant Rupicapra rupicapra are reported. The study was carried out after the fall out of radioactive contamination from the nuclear accident at Chernobyl (May 1986) and showed the high prevalence of teratologic forms in representatives of Ostertaginae (3.1% of the entire population of male worms).

Effect of ultraviolet radiation on the hatchability and survival of eggs and larvae of sheep nematode.

The hatchability of sheep gastrointestinal nematode eggs exposed to ultraviolet (UV) radiation and the activity of the hatched larvae were examined. Hatchability decreased with increasing exposure to radiation. The difference in hatchability of eggs irradiated for 15,30 and 60 minutes were highly significant (p < 0.01 dalpha = 3.07, 3.24 and 3.75) compared with the hatchability of the nonirradiated eggs. The life span of irradiated larvae was shortened, only 20% of those expose to UV radiation 60 minutes survive for 2 days as against 100% survival rate in the non-irradiated larvae. Batches of nematode larvae (L1) were irradiated with ultraviolet (UV) light for varying time interval to determine the influence of radiation on the transmission potential of the irradiated larvae. There was a decrease in the survival rate of the hatched free-swimming larvae that corresponded with the increasing radiation exposure time.