Spatial association of Mycobacterium bovis infection in cattle and badgers at the pasture interface in an endemic area in France.

Despite control and surveillance programmes, Mycobacterium bovis, the main aetiologic agent of bovine tuberculosis (bTB), is still detected on cattle farms and in wildlife populations in France, especially in badgers in the French Côte-d'Or département. The aim of our study was to find out if infected badgers were trapped significantly closer to pastures of infected farms than non-infected badgers and, if so, to determine the most efficient distance around those pastures for badger trapping, particularly for surveillance purposes. We studied two subareas (southern and northern), chosen based on natural barriers to badger movements and according to the presence of pastures belonging to infected farms (POIFs) and infected or non-infected badgers. In each subarea, we computed the shortest distances D0 and D between badgers trapped a given year n between 2015 and 2019 (n = 59 infected and n = 1535 non-infected badgers for D0; n = 53 infected and n = 1476 non-infected badgers for D) and POIFs designated as infected between the year n - 4 and n + 1 (respectively n = 373 and n = 388 POIFs). D0 was calculated without considering spoligotypes, while D was calculated considering the possible epidemiological link between infected badgers and POIFs by using bTB spoligotype information. Then, we computed the observed mean and median of the D0 and D distances and used a bootstrap analysis to test if infected badgers were found significantly closer to POIFs than non-infected badgers. We observed that infection of badgers was not independent of distance from POIF in both subareas but distances (D0 or D) were different between the northern and southern subarea. In the northern subarea, which displays a mosaic landscape (mean and median D distances were respectively 612 m and 303 m for infected badgers), infected badgers indeed were trapped closer to POIFs, considering D0 and D. In the southern subarea, predominantly forested, infected badgers were significantly closer to POIFs than non-infected badgers when considering D0 but not for D (mean and median D distances were respectively 7148 m and 4831 m for infected badgers). These results will help to determine the most efficient distance from POIFs to trap badgers to determine their infection status in countryside landscapes. They also highlight the need to better understand the epidemiological systems at play in more forested landscapes where badgers may behave differently or other susceptible sympatric wild species might play a more important role in the circulation of M. bovis, both phenomena contributing to badger infection at greater distances from POIFs.

Evaluation of the performance of the IFN-γ release assay in bovine tuberculosis free herds from five European countries.

The diagnostic methods for granting and maintenance of the official tuberculosis-free (OTF) status and for intra-Community movement of cattle are the tuberculin skin tests (single or comparative) and the interferon-γ (IFN-γ) release assay (IGRA). However, until now, IGRAs have been primarily applied in infected farms in parallel to the skin test to maximize the number of infected animals detected. Therefore, an evaluation of the performance of IGRAs in OTF herds to assess whether if their specificity is equal to or higher than that of the skin tests is needed. For this, a panel of 4365 plasma samples coming from 84 OTF herds in six European regions (five countries) was assembled and analysed using two IGRA kits, the ID Screen® Ruminant IFN-g (IDvet) and the Bovigam™ TB Kit (Bovigam). Results were evaluated using different cut-offs, and the impact of herd and animal-level factors on the probability of positivity was assessed using hierarchical Bayesian multivariable logistic regression models. The percentage of reactors ranged from 1.7 to 21.0% (IDvet: S/P ≥ 35%), and 2.1-26.3% (Bovigam: ODbovis-ODPBS ≥ 0.1 and ODbovis-ODavium ≥ 0.1) depending on the region, with Bovigam disclosing more reactors in all regions. The results suggest that specificity of IGRAs can be influenced by the production type, age and region of origin of the animals. Changes in the cut-offs could lead to specificity values above 98-99% in certain OTF populations, but no single cut-off yielding a sufficiently high specificity (equal or higher than that of skin tests) in all populations was identified. Therefore, an exploratory analysis of the baseline IFN-γ reactivity in OTF populations could help to assess the usefulness of this technique when applied for the purpose of maintaining OTF status.

Non thermal 2.45 GHz electromagnetic exposure causes rapid changes in Arabidopsis thaliana metabolism.

Numerous studies report different types of responses following exposure of plants to high frequency electromagnetic fields (HF-EMF). While this phenomenon is related to tissue heating in animals, the situation is much less straightforward in plants where metabolic changes seem to occur without tissue temperature increase. We have set up an exposure system allowing reliable measurements of tissue heating (using a reflectometric probe and thermal imaging) after a long exposure (30 min) to an electromagnetic field of 2.45 GHz transmitted through a horn antenna (about 100 V m-1 at the plant level). We did not observe any heating of the tissues, but we detected rapid increases (60 min) in the accumulation of transcripts of stress-related genes (TCH1 and ZAT12 transcription factor) or involved in ROS metabolism (RBOHF and APX1). At the same time, the amounts of hydrogen peroxide and dehydroascorbic acid increased while glutathione (reduced and oxidized forms), ascorbic acid, and lipid peroxidation remained stable. Therefore, our results unambiguously show that molecular and biochemical responses occur rapidly (within 60min) in plants after exposure to an electromagnetic field, in absence of tissue heating.

High-frequency, high-intensity electromagnetic field effects on Saccharomyces cerevisiae conversion yields and growth rates in a reverberant environment.

Studies of the effects of electromagnetic waves on Saccharomyces cerevisiae emphasize the need to develop instrumented experimental systems ensuring a characterization of the exposition level to enable unambiguous assessment of their potential effects on living organisms. A bioreactor constituted with two separate compartments has been designed. The main element (75% of total volume) supporting all measurement and control systems (temperature, pH, agitation, and aeration) is placed outside the exposure room whereas the secondary element is exposed to irradiation. Measurements of the medium dielectric properties allow the determination of the electromagnetic field at any point inside the irradiated part of the reactor and are consistent with numerical simulations. In these conditions, the growth rate of Saccharomyces cerevisiae and the ethanol yield in aerobic conditions are not significantly modified when submitted to an electromagnetic field of 900 and 2400 MHz with an average exposition of 6.11 V.m-1 and 3.44 V.m-1 respectively.

Low-amplitude, high-frequency electromagnetic field exposure causes delayed and reduced growth in Rosa hybrida.

It is now accepted that plants perceive high-frequency electromagnetic field (HF-EMF). We wondered if the HF-EMF signal is integrated further in planta as a chain of reactions leading to a modification of plant growth. We exposed whole small ligneous plants (rose bush) whose growth could be studied for several weeks. We performed exposures at two different development stages (rooted cuttings bearing an axillary bud and 5-leaf stage plants), using two high frequency (900MHz) field amplitudes (5 and 200Vm(-1)). We achieved a tight control on the experimental conditions using a state-of-the-art stimulation device (Mode Stirred Reverberation Chamber) and specialized culture-chambers. After the exposure, we followed the shoot growth for over a one-month period. We observed no growth modification whatsoever exposure was performed on the 5-leaf stage plants. When the exposure was performed on the rooted cuttings, no growth modification was observed on Axis I (produced from the elongation of the axillary bud). Likewise, no significant modification was noted on Axis II produced at the base of Axis I, that came from pre-formed secondary axillary buds. In contrast, Axis II produced at the top of Axis I, that came from post-formed secondary buds consistently displayed a delayed and significant reduced growth (45%). The measurements of plant energy uptake from HF-EMF in this exposure condition (SAR of 7.2 10(-4)Wkg(-1)) indicated that this biological response is likely not due to thermal effect. These results suggest that exposure to electromagnetic field only affected development of post-formed organs.

Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca2+ leak after one session of high-intensity interval exercise.

High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca(2+) release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca(2+) leak at rest, and depressed force production due to impaired SR Ca(2+) release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca(2+)-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group.

Rift valley fever in humans and animals in Mayotte, an endemic situation?

Retrospective studies and surveillance on humans and animals revealed that Rift Valley Fever virus (RVFV) has been circulating on Mayotte for at least several years. A study was conducted in 2011 to estimate the seroprevalence of RVF in humans and in animals and to identify associated risk factors. Using a multistage cluster sampling method, 1420 individuals were enrolled in the human study, including 337 children aged 5 to 14 years. For the animal study, 198 seronegative ruminants from 33 randomly selected sentinel ruminant herds were followed up for more than one year. In both studies, information on environment and risk factors was collected through a standardized questionnaire. The overall weighted seroprevalence of RVFV antibodies in the general population aged ≥5 years was 3.5% (95% CI 2.6-4.8). The overall seroprevalence of RVFV antibodies in the ruminant population was 25.3% (95% CI 19.8-32.2). Age (≥15), gender (men), place of birth on the Comoros, living in Mayotte since less than 5 years, low educational level, farming and living close to a water source were significantly associated with RVFV seropositivity in humans. Major risk factors for RFV infection in animals were the proximity of the farm to a water point, previous two-month rainfall and absence of abortions disposal. Although resulting in few clinical cases in humans and in animals, RVFV has been circulating actively on the island of Mayotte, in a context of regular import of the virus from nearby countries through illegal animal movements, the presence of susceptible animals and a favorable environment for mosquito vectors to maintain virus transmission locally. Humans and animals share the same ways of RVFV transmission, with mosquitoes playing an important role. The studies emphasize the need for a one health approach in which humans and animals within their ecosystems are included.

Prevalence of Rift Valley Fever among ruminants, Mayotte.

Rift Valley fever threatens human and animal health. After a human case was confirmed in Comoros in 2007, 4 serosurveys among ruminants in Mayotte suggested that Rift Valley fever virus had been circulating at low levels since 2004, although no clinical cases occurred in animals. Entomologic and ecologic studies will help determine outbreak potential.

Human keratinocytes in culture exhibit no response when exposed to short duration, low amplitude, high frequency (900 MHz) electromagnetic fields in a reverberation chamber.

We exposed normal human epidermal keratinocytes to short duration, high frequency, and low amplitude electromagnetic fields, similar to that used by mobile phone technologies. We paid particular attention to the control of the characteristics of the electromagnetic environment generated within a mode stirred reverberation chamber (statistical homogeneity and isotropy of the field and SAR distribution). Two non-thermal exposure conditions were tested on the epidermal cells: 10-min exposure with a field amplitude of 8 V/m, and 30 min with 41 V/m. Corresponding specific absorption rates ranged from 2.6 to 73 mW/kg (continuous wave, 900 MHz carrier frequency). We collected RNA from cells subjected to these conditions and used it for a large-scale microarray screening of over 47000 human genes. Under these conditions, exposure of keratinocytes to the electromagnetic field had little effect; only 20 genes displayed significant modulation. The expression ratios were very small (close to 1.5-fold change), and none of them were shared by the two tested conditions. Furthermore, those assayed using polymerase chain reaction did not display significant expression modulation (overall mean of the exposed samples: 1.20 ± 0.18). In conclusion, the data presented here show that cultured keratinocytes are not significantly affected by EMF exposure.

Changes in 13C/12C of oil palm leaves to understand carbon use during their passage from heterotrophy to autotrophy.

The carbon isotope composition of leaf bulk organic matter was determined on the tropical tree Elaeis guineensis Jacq. (oil palm) in North Sumatra (Indonesia) to get a better understanding of the changes in carbon metabolism during the passage from heterotrophy to autotrophy of the leaves. Leaf soluble sugar (sucrose, glucose and fructose) contents, stomatal conductance and dark respiration, as well as leaf chlorophyll and nitrogen contents, were also investigated. Different growing stages were sampled from leaf rank -6 to rank 57. The mean values for the delta(13)C of bulk organic matter were -29.01 +/- 0.9 per thousand for the leaflets during the autotrophic stage, -27.87 +/- 1.08 per thousand for the petioles and -28.17 +/- 1.09 per thousand for the rachises, which are in the range of expected values for a C(3) plant. The differences in delta(13)C among leaf ranks clearly revealed the changes in the origin of the carbon source used for leaf growth. Leaves were (13)C-enriched at ranks below zero (around -27 per thousand). During this period, the 'spear' leaves were completely heterotrophic and reserves from storage organs were mobilised for the growth of these young emerging leaves. (13)C-depletion was then observed when the leaf was expanding at rank 1, and there was a continuous decrease during the progressive passage from heterotrophy until reaching full autotrophy. Thereafter, the delta(13)C remained more or less constant at around -29.5 per thousand. Changes in sugar content and in delta(13)C related to leaf ranks showed an interesting similarity of the passage from heterotrophy to autotrophy of oil palm leaves to the budburst of some temperate trees or seed germination reported in the literature.

High frequency (900 MHz) low amplitude (5 V m-1) electromagnetic field: a genuine environmental stimulus that affects transcription, translation, calcium and energy charge in tomato.

Using an especially-designed facility, the Mode Stirred Reverberation Chamber, we exposed tomato plants (Lycopersicon esculentum Mill. VFN8) to low level (900 MHz, 5 V m(-1)) electromagnetic fields for a short period (10 min) and measured changes in abundance of three specific mRNA soon after exposure. Within minutes of electromagnetic stimulation, stress-related mRNA (calmodulin, calcium-dependent protein kinase and proteinase inhibitor) accumulated in a rapid, large and 3-phase manner typical of an environmental stress response. Accumulation of these transcripts into the polysomal RNA also took place (indicating that the encoded proteins were translated) but was delayed (indicating that newly-synthesized mRNA was not immediately recruited into polysomes). Transcript accumulation was maximal at normal Ca(2+) levels and was depressed at higher Ca(2+), especially for those encoding calcium-binding proteins. Removal of Ca(2+) (by addition of chelating agents or Ca(2+) channel blocker) led to total suppression of mRNA accumulation. Finally, 30 min after the electromagnetic treatment, ATP concentration and adenylate energy charge were transiently decreased, while transcript accumulation was totally prevented by application of the uncoupling reagent, CCCP. These responses occur very soon after exposure, strongly suggesting that they are the direct consequence of application of radio-frequency fields and their similarities to wound responses strongly suggests that this radiation is perceived by plants as an injurious stimulus.

A possible role for extra-cellular ATP in plant responses to high frequency, low amplitude electromagnetic field.

In parallel to evoking the accumulation of stress-related transcripts, exposure to low level 900 MHz EMF affected the levels of ATP, the main energy molecule of the cell. Its concentration dropped rapidly (27% after 30 min) in response to EMF exposure, along with a 18% decrease in the adenylate energy charge (AEC), a good marker of cell energy status. One could interpret this decrease in ATP and AEC in a classical way, i.e., as the result of an increase in cellular energy usage, but recent work brings exciting new insights in pointing out a signalling function for ATP, especially in the stress physiology context where it could trigger both reactive oxygen species and calcium movement (this latter being involved in plant responses to EMF exposure). In this addendum, we discuss our results within this new perspective for ATP function.

Intercellular communication in plants: evidence for two rapidly transmitted systemic signals generated in response to electromagnetic field stimulation in tomato.

Exposing all of a wild-type tomato plant to electromagnetic radiation evoked rapid and substantial accumulation of basic leucine-zipper transcription factor (bZIP) mRNA in the terminal leaf (#4) with kinetics very similar to that seen in response to wounding, while in the abscisic acid (ABA) mutant (Sitiens), the response was more rapid, but transient. Submitting just the oldest leaf (#1) of a wild-type plant to irradiation evoked bZIP mRNA accumulation both locally in the exposed leaf and systemically in the unexposed (distant) leaf #4, although systemic accumulation was delayed somewhat. Accumulation of Pin2 mRNA was less than bZIP in both the exposed and distant leaves in wild type, but there was no delay in the systemic response. In Sitiens, bZIP mRNA accumulation was far less than in wild type in both local and distant leaves, while Pin2 mRNA accumulation was stronger in the exposed leaf, but totally prevented in the systemic leaf. In the jasmonic acid (JA) mutant (JL-5) and in wild-type plants treated with the ABA biosynthesis inhibitor, naproxen, responses were similar to those in the ABA mutant, while treatment of the exposed leaf with calcium antagonists totally abolished both local and systemic increases in bZIP transcript accumulation.

Plants Respond to GSM-Like Radiation.

In this article, we propose that an organism's general architecture is of primary importance for its ability to perceive electromagnetic radiation. Animals develop mainly as volumes for internal assimilation and appendages to increase their mobility, while plants develop as surfaces to optimize interaction with the environment. As a consequence, the proportion of cells directly interacting with EMF radiation at the organism/environment interface is much higher in plants than it is in animals, making them especially suited to study EMF effects on life.