Changes in the activity and conditioned-reflex behavior of white rats during and after chronic microwave irradiation

Albino rats were exposed to chronic (1-3 months) electromagnetic radiation (2375 MHz; 1, 5, 10, 50 and 500 microW/cm2; 7 hours a day). Inhibition of the activity during the open field tests and diminution of consolidation of the defence conditioned reflexes in a shuttle chamber occurred during exposure (5 to 500 microW/cm2) while the activity increased and reflexes consolidation gradually normalized during the post-irradiation period.     

Survival of Phytophthora ramorum hyphae after exposure to temperature extremes and various humidities

We examined the effect of short-term exposure to high and low temperatures and a range of relative humidity (RH) on survival of Phytophthora ramorum hyphae. Spore-free hyphal colonies were grown on dialysis squares atop V8 medium. Colonies were transferred to water agar plates positioned at 27.5-50 C on a thermal gradient plate and incubated 2.5-480 min. For low temperature trials colonies were transferred to vials of distilled water and incubated in a water bath at -5 to -25 C for 1-24 h. In the relative humidity trials hyphal colonies were transferred to sealed humidity chambers containing various concentrations of glycerin for 1-8 h. Relative humidity was 41-93% at 20 C and 43-86% at 28 C. Survival in all trials was characterized by growth from dialysis squares into V8 medium. Temperatures of 37.5-40 C were lethal to P. ramorum hyphae within several hours, and temperatures of 42.5-50 C were lethal within minutes. Exposure to 32.5 and 35 C resulted in reduced survival over 8 h, while 30 C had no effect on three of four isolates. Hyphal colonies demonstrated considerable tolerance to cold, with all isolates surviving a 24 h exposure to -5 C. Survival diminished over time at lower temperatures, however a few colonies survived 24 h exposure to -25 C. Temperature also affected the ability of hyphal colonies to withstand reduced humidity. A RH of 41-43% was lethal in 2 h at 28 C compared to 8 h at 20 C. Three of four isolates were unaffected by an 8 h exposure to 81 and 95% RH at 20 C, and 73 and 86% RH at 28 C. Isolate differences were apparent in tolerance to freezing temperatures and reduced humidity. From these results it is apparent that the cold temperatures found in the northeastern USA are not likely to prevent the establishment of P. ramorum. There is also the potential for hyphae, and presumably spores, to survive periods of high humidity on the leaf surface in the absence of free water.     

Strawberry Tree Blight in Spain, a New Disease Caused by various Phytophthora Species

During surveys for Phytophthora ramorum in garden centres in Majorca, Spain, 31 isolates of Phytophthora were recovered from potted strawberry trees ( Arbutus unedo ) showing leaf and twig blights. Many isolates of Phytophthora syringae and Phytophthora citrophthora as well as single isolates of P. ramorum, Phytophthora tropicalis and Phytophthora nicotianae were identified on morphological features and on the sequences of the internal transcribed spacer regions from ribosomal DNA genes. Phytophthora syringae was collected most frequently in late autumn and winter, whereas P. citrophthora was dominant during late summer and autumn. In vitro pathogenicity of P. syringae and P. citrophthora was compared with that of P. ramorum by inoculating intact detached leaves of A. unedo with zoospores and twigs with mycelial plugs. In addition, in vitro sporangial production was examined on inoculated excised leaves and on agar plugs at 12, 15 and 20°C. Phytophthora citrophthora produced the largest lesions both on leaves and on twigs at all temperatures. Phytophthora ramorum formed lesions comparable in size to those of P. syringae , but it significantly produced more sporangia on excised leaves and agar plugs. In a log inoculation assay, P. syringae caused large lesions in the inner bark, whereas those of P. ramorum were moderate. Strawberry tree blight has not yet been observed in natural ecosystems in the western Mediterranean areas. Possible biological and environmental limitations hindering disease spread in the wild are discussed.     

Aspergillus carbonarius growth and ochratoxin A production on a synthetic grape medium in relation to environmental factors

AIMS: The effects of water activity (0.90-0.99 a(w)), temperature (15-37 degrees C), and their interaction on growth and ochratoxin A (OTA) production by eight isolates of Aspergillus carbonarius were investigated on synthetic nutrient medium (SNM) with composition similar to grapes. METHODS AND RESULTS: Growth data were modelled by an multiple linear regression and response surface models were obtained. Aspergillus carbonarius grew much faster at 30 degrees C than at the other temperature levels tested and its growth rate increased with increasing a(w), maximum growth rate being between 0.95 and 0.99 a(w). In general, isolates grew faster at 35-37 degrees C than at 20 degrees C, although no significant differences were found between these temperatures. OTA accumulation was also favoured by high a(w) levels, and although it was observed in the whole range of temperatures, maximum amounts were detected at 20 degrees C. No OTA was found at the most unfavourable growth conditions. CONCLUSIONS: Optimum a(w) level for growth seems to correspond with optimum for OTA production, meanwhile the most propitious temperature for the toxin production was below the best one for growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Prediction of A. carbonarius growth would allow estimating their presence and therefore, the OTA production, as it was found that conditions for the toxin production were more limited than those permitting growth.     

Effect of microwaves of nonthermal intensity on the number of aberrant hepatocytes in rats

It was shown on rats that the effect of permanently generated electromagnetic field (a whole-body exposure) during 45 days (7h a day, the energy flux density of 10 microW/cm2) caused a decrease in number of hepatocytes with the affected chromosomes. Some part of animals exposed to higher energy loading (PD - 50 microW/cm2, 20 days, 7 h/day) showed the increase of aberrant cells level. A single exposure at 500 microW/cm2 and a ten-fold exposure at 50 microW/cm2 (10 days, 7h a day) were shown to be ineffective.     

Photoperiodic and light spectral conditions which inhibit circulating concentrations of thyroxine in the male hamster

Adult male Syrian hamsters were exposed daily for 12 weeks to 11 h/day of cool white fluorescent light (350 +/- 50 microW/cm2) followed by an additional 3 h of near ultraviolet (339-317 nm), blue (435-500 nm), green (515-550 nm), yellow (558-636 nm) or red (653-668 nm) light at an irradiance of 0.2 microW/cm2 or to total darkness. Animals exposed to the wavelengths between 558-668 nm (yellow or red half peak bandwidths) or those receiving a total of 13 h of darkness/day had suppressed circulating levels of thyroxine (T4), a depressed free T4 index (FT4I) and a higher T3/T4 ratio compared to animals receiving a total of 14 h of white light (350 +/- 50 microW/cm2). These results suggest that specific wavelengths of light can affect the neuroendocrine-thyroid axis.     

Heat shock proteins and thermotolerance in a cultured cell line from the Mediterranean fruit fly, Ceratitis capitata.

Heat shock proteins (hsps) were identified in a cell line from the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae) exposed to elevated temperatures. Cells produced three hsps (Mr 87,000, 69,000, and 34,000) in response to a temperature shift from 26 degrees C to 37 degrees C (30-60 min) with a concomitant decrease in synthesis of most other cellular proteins. Synthesis of low Mr hsps was not evident. The heat shock response is triggered within 30 min at temperatures from 33 degrees C to 41 degrees C. At temperatures greater than 41 degrees C protein synthesis was shut down. Within 2-3 h after return to 26 degrees C, synthesis of proteins repressed at the higher temperatures resumed production while the major hsps disappear. Heat shock proteins were not produced in the presence of actinomycin D. Evaluations on the role of hsps in conferring thermotolerance to the cells showed an increase in cell viability in heat-shocked cells over non-heat-shocked cells (after 3 and 10 days) when subsequently placed at 45 degrees C for 1 h, a normally lethal temperature. Heat shock alone had little effect on subsequent cell viability or growth at 26 degrees C. These results suggest that hsps produced by these cells may aid in the maintenance of cell integrity and thus play a transitory role in thermotolerance.     

Effect oh millimeter waves on the immune system in mice with experimental tumors

The effect of low-level millimeter fractionated radiation on the production of tumor necrosis factor, intreleukin-2, interleukine-3, and nitric oxide and on the activity of natural killer cells and proliferation of T and B lymphocytes in mice was studied. Cell activity was measured in four groups of male Balb/c mice (control, exposed, tumor-bearing unexposed, and exposed tumor-bearing animals) within 30 days of tumoral growth and microwave exposure (42.2 GHz, 10 Hz amplitude modulation, 0.5 microW/cm2, 1.5 h daily). A significant increase in the production of tumor necrosis factor and nitric oxide and in the activity of natural killer cells was observed at the early stage of tumor development; this effect was considered as adaptive response. In healthy mice, millimeter radiation produced both stimulating and immunodepressive effects. The changes were nonmonotonous; as the exposure duration was increased, the stimulating effect became weaker and on day 30 it was not observed. Irradiation of tumor-bearing mice did not induce any significant changes in the activity of cells compared to unirradiated tumor-bearing animals. Moreover, exposure to millimeter waves impaired some characteristics of cell immunity in tumor-bearing mice. It was concluded that low-intensity millimeter waves do not increase the resistance against tumor as it was shown earlier in our experiments with centimeter waves.     

Clonal expansion of the Belgian Phytophthora ramorum populations based on new microsatellite markers

Co-existence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, which begs the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a 7-year survey. Our main objectives were genetic characterization of this population to test for sexual reproduction, determination of population structure, evolution and spread, and evaluation of the effectiveness and impact of control measures. Novel, polymorphic simple sequence repeat (SSR) markers were developed after screening 149 candidate loci. Eighty isolates of P. ramorum, broadly representing the Belgian population, were analyzed using four previously described and three newly identified polymorphic microsatellite loci as well as amplified fragment length polymorphisms. SSR analysis was most informative and was used to screen the entire Belgian population. Thirty multilocus genotypes were identified, but 68% of the isolates belonged to the main genotype EU1MG1. Although accumulated mutation events were detected, the overall level of genetic diversity within the Belgian isolates of P. ramorum appears to be limited, indicating a relatively recent clonal expansion. Based on our SSR analysis there is no evidence of sexual recombination in the Belgian population of P. ramorum . Metalaxyl use decreased the genetic diversity of P. ramorum until 2005, when the majority of the isolates had become resistant. Most genotypes were site-specific and despite systematic removal of symptomatic and neighbouring plants, some genotypes were detected over a period of several years at a single site, sometimes discontinuously, indicating (latent) survival of the pathogen at those sites.     

Effect of centimeter microwaves and the combined magnetic field on the tumor necrosis factor production in cells of mice with experimental tumors

The effect of fractionated exposure to low-intensity microwaves (8.15-18 GHz, 1 microW/cm2, 1.5 h daily for 7 days) and combined weak magnetic field (constant 65 1 microT; alternating--100 nT, 3-10 Hz) on the production of tumor necrosis factor in macrophages of mice with experimental solid tumors produced by transplantation of Ehrlich ascites carcinoma was studied. It was found that exposure of mice to both microwaves and magnetic field enhanced the adaptive response of the organism to the onset of tumor growth: the production of tumor necrosis factor in peritoneal macrophages of tumor-bearing mice was higher than in unexposed mice.     

The phenomenon of adaptive immunity in exposure to nonionizing microwave radiation]

In experiments with albino rats exposed to microwaves (500 microW/cm2), a model of adaptive immunity was developed by transferring lymphoid cells of exposed animals. The effect of microwave radiation was shown to cause autoimmune disorders that were displayed against the background of the structural and functional disturbances of the hematoencephalic barrier.     

If you can’t stand the heat,stay out of the city: Thermal reaction norms of chitinolytic fungi in an urban heat island

Elevated soil and air temperatures in urban heat islands have been exerting evolutionary pressure on organisms for decades in some cities. We measured thermal reaction norms (18–26 °C) for growth rate of four species of common chitinolytic fungi from an oak forest in an urban heat island and a corresponding rural area. Urban isolates of Chrysosporium pannorum and Trichoderma koningii grew faster than rural isolates at 26 °C, but grew slower than rural isolates at 18 °C. Urban isolates of Torulomyces lagena and Penicillium bilaii grew as fast or faster than rural isolates at all temperatures. These differences in thermal reaction norms between urban and rural isolates suggest that urbanization has caused both thermal specialization and counter-gradient variation in the fungal community.     

Influence of light intensity on plasma melatonin and locomotor activity rhythms in tench

Melatonin production by the pineal organ is influenced by light intensity, as has been described in most vertebrate species, in which melatonin is considered a synchronizer of circadian rhythms. In tench, strict nocturnal activity rhythms have been described, although the role of melatonin has not been clarified. In this study we investigated daily activity and melatonin rhythms under 12:12 light-dark (LD) conditions with two different light intensities (58.6 and 1091 microW/cm2), and the effect of I h broad spectrum white light pulses of different intensities (3.3, 5.3, 10.5, 1091.4 microW/cm2) applied at middarkness (MD) on nocturnal circulating melatonin. The results showed that plasma melatonin in tench under LD 12:12 and high light conditions displayed rhythmic variation, where values at MD (255.8 +/- 65.9 pg/ml) were higher than at midlight (ML) (70.7 +/- 31.9 pg/ml). Such a difference between MD and ML values was reduced in animals exposed to LD 12: 12 and low light intensity. The application of 1 h light pulses at MD lowered plasma melatonin to 111.6 +/- 3.2 pg/ml (in the 3.3-10.5 microW/cm2 range) and to 61.8 +/- 18.3 pg/ml (with the 1091.4 microW/cm2 light pulse) and totally suppressed nocturnal locomotor activity. These results show that melatonin rhythms persisted in tench exposed to low light intensity although the amplitude of the rhythm is affected. In addition, it was observed that light pulses applied at MD affected plasma melatonin content and locomotor activity. Such a low threshold suggests that the melatonin system is capable of transducing light even under dim conditions, which may be used by this nocturnal fish to synchronize to weak night light signals (e.g., moonlight cycles).     

Biological control of Phytophthora ramorumon rhododendron

Phytophthora ramorum was found in Poland in 2000 as the causal agent of rhododendron blight. Besides eradication of diseased plants and rhododendron growing around, chemical and biological control of the pathogen is necessary. In this study in vitro activity of grapefruit extract and chitosan in the inhibition of P. ramorum growth and sporulation and their efficacy in the control of leaf and stem rot development was evaluated. Amendment of V8 juice agar and soil leachate with grapefruit extract resulted in the inhibition of colony growth and sporulation of P. ramorum. Zoosporangia were more susceptible to the extract than pathogen hyphae and chlamydospores. Chitosan only slightly inhibited the colony growth and zoosporngia production. Spraying of rhododendron inoculated with P. ramorum with grapefruit extract at conc. 165 microg/cm3 inhibited 2-3 times the spread of necrosis on stems and leaves. Pre- and postinoculation spraying of rhododendrons with chitosan at conc. of 1000 microg/cm3 suppressed the disease spread about 40%.     

Myelokaryocyte mitotic activity during microwave irradiation (2375 MHz)

Changes in mitotic activity of myelocaryocytes exposed to super-high frequency field (2375 MHz) of 10, 50 and 500 microW/cm2 for a month show the influence of this factor on the DNA synthesis, premitotic processes and cell reproduction biorhythms depending on the radiation intensity.     

Proteolytic anaerobic bacteria from lake sediments of Antarctica

Amongst twenty five proteolytic bacteria isolated from lake sediment samples of Antarctica, six isolates were selected based on SDS PAGE protein profile and zone of hydrolysis on casein agar at 10 degrees C. Most of the cultures were rod shaped and motile with two showing terminal bulging spores. Isolates grew between 5 degrees C to 37 degrees C and protease was induced in the late log, stationary or death phase. Isolate SPA-3 grew maximally at 10 degrees C and SPA-6 at 37 degrees C while others preferred 20 degrees C-30 degrees C for growth. The growth and protease production on casein, skimmed milk, bovine serum albumin and gelatin varied with the isolates. Acetate was the dominant volatile fatty acid (24-66% of total VFA) produced during hydrolysis of protein substrate.     

Seasonal changes in tumor necrosis factor production in hibernating animals in normal conditions and under the effects of electromagnetic and ionizing radiation

Production of tumor necrosis factor (TNF) has been investigated in peritoneal macrophages and splenic T cells of Arctic Yakutian ground squirrel (Citellus Undulatus Pallas) upon in vitro action of electromagnetic and ionizing radiation during annual cycle. The significant activation of TNF production in the cells of awaken ground squirrels in winter and increasing level of the lymphokine production at spring-summer period has been indicated. The level of TNF production in splenic T cells was not changed during whole year. The electromagnetic radiation (EMR) of low intensity (8.15-18 GHz, 1 microW/cm2) induced an augmentation of both secretory and proliferative activity in TNF-producing cells. Ionizing radiation suppressed T cell proliferation, but the doses 2 and 5 Gy resulted in a significant stimulation of TNF production in T cells and macrophages.     

Morphology of three polycentric rumen fungi and description of a procedure for the induction of zoosporogenesis and release of zoospores in cultures

Three polycentric rumen fungi, LL, LC2 and Ruminomyces elegans (C2), isolated from the rumen of cattle were grown in six culture media. LL and LC2 were morphologically similar. Their characteristics resembled those of Orpinomyces and Neocallimastix joyonii, and they grew well and produced sporangia after 3-4 d growth in all the media. R. elegans differed morphologically from LL and LC2, but although it also grew well in all media, abundant sporangia occurred only after 2-3 d growth in media containing cellulose. Undifferentiated sporangia were produced by all three isolates; differentiation of the sporangia did not occur in the spent growth media. However, if thalli possessing recently-formed sporangia were transferred to, or flooded with, fresh liquid medium or rumen fluid, zoosporogenesis and liberation of zoospores occurred within 17-20 min for isolates LL and LC2 and 30 min for R. elegans. Procedures for inducing zoosporogenesis by polycentric anaerobic fungi are described.     

TEMPERATURE-GROWTH RESPONSES OF ALGAL ISOLATES FROM ANTARCTIC OASES1

Thirty-five taxa (128 clonal cultures) of Antarctic algae isolated from various habitats were assayed for growth over a range of 2–34°C. Isolates, all unialgal and two axenic, varied markedly in their temperature-growth responses. Only four taxa belonging to either the Chlamydomonadaceae or Ulotrichaceae were obligately cold-adapted and incapable of growth at ≥20°C. All isolates grew at temperatures ranging from 7.5 to 18°C, and a few were incapable of growth at ≤5°C. Over one-third of the isolates grew at 30°C, but none grew at 34°C. Percentages of cold-adapted clones correlated well with the more stable low temperature habitats. Four chlamydomonad isolates displayed optimum temperatures for growth near their maximum temperatures for growth, both temperatures being well above those of the native habitats. This temperature-growth response suggests a closer relationship to algae from more moderate thermal regions than one might have supposed. However, the ability to grow at low temperatures and the inability to grow at 34°C suggest that these Antarctic algae are cold temperature adapted. Growth capability at low in situ temperatures is considered more useful ecologically than physiologically-defined categories for algae based on their maximum temperature for growth.     

Influence of culture media and environmental factors on mycelial growth and pycnidial production of Sphaeropsis pyriputrescens

Sphaeropsis pyriputrescens, the causal agent of Sphaeropsis rot of pears and apples, is a recently described species. In this study the effects of culture media, temperature, water potential, pH and light on mycelial growth and pycnidial production of S. pyriputrescens were evaluated. Apple juice agar and pear juice agar were most suitable for mycelial growth of all six isolates tested. Cornmeal agar was not suitable for either mycelial growth or pycnidial production. The fungus grew from -3 to 25 C, with optimum growth at 20 C and no growth at 30 C. The fungus grew at water potential as low as -5.6 MPa on potassium chloride-amended potato-dextrose agar (PDA). Hyphal extension was not observed at -7.3 MPa after 10 d incubation, but growth resumed when the inoculum plugs were placed on PDA. The fungus grew at pH 3.3-6.3 and optimum growth was at pH 3.3-4.2. No mycelial growth was observed at pH above 7.2 after 10 d incubation, but growth resumed when the inoculum plugs were transferred onto PDA. Regardless of medium tested, few pycnidia formed at 20 C in the dark. Pycnidial production was enhanced significantly by fluorescent light, but continuous light appeared to reduce pycnidial production, depending on the medium. Oatmeal agar (OMA) was most suitable for production of pycnidia and conidia. Pycnidia that formed on 3 wk old OMA cultures at 20 C under 12 h light/12 h dark produced abundant conidia, and the technique is recommended for inoculum production.