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Marie Curie directed a research laboratory for 28 years. Between 1906 and 1934, forty five women worked under her guidance. Some were, and are, well-known in their own countries as their first woman full professor such as Ellen Gleditsch or Margaret von Wrangel, but for twenty eight of them, who were often French, nothing has ever been written. The strong presence of women in Marie Curie's laboratory has often been highlighted and has been considered as an exception, and the result of deliberate choice. Of course, these women did not choose this workplace by accident. They knew its director was a woman, a laureate of one, and after 1911, two Nobel Prizes, who was leading a well-equipped laboratory with an important radioactive source. But how did Marie Curie selected her collaborators among the many applications she received? Was her choice influenced by gender? A prosopographical research based on genealogical researches and new sources explains this presence contextually and sheds light on several questions : where did these women come from, what were their social and geographic origins, did they occupy any specific cultural or technical area inside Curie's lab, what future did they have after the laboratory? Through their lives, we can question the existence, or not, of a one profile of the female researcher in scientific areas in France.

In this article, an investigation into the natural radioactivity content in natural inorganic pigments was carried out, together with the assessment of the radiological health risk for the public related to external exposure to ionizing radiations, via High-Purity Germanium (HPGe) γ-ray spectrometry measurements and the calculation of several indices like the absorbed γ-dose rate (D), the annual effective dose equivalent outdoor (AEDEout) and indoor (AEDEin), and the activity concentration index (I). From the obtained results, it was possible to reasonably exclude radiological hazard effects. In addition, Pearson’s correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA) were carried out with the aim of determining correlations between natural radioactivity content and radiological indices and with the analyzed samples. As a result, five clusters of the investigated pigments were recognized at the highest level of detail based on their chemical composition and mineralogical nature.

Enterosorption is a cost-effective and efficient approach to reducing the impact of chronic exposure to heavy metals and radionuclides. As an auxiliary method to medical treatment, it can protect population chronically exposed to the intake of heavy metals or radioactivity due to industrial activities or in the aftermath of technogenic or natural accidents. This paper assesses the current state of the art in the treatment of acute and chronic heavy metal poisoning.

In the present paper, an investigation on the natural and anthropic radioactivity and heavy metals content in a basalt aggregate for concrete from Sicily, Southern Italy, was performed as a case study. In particular, the evaluation of the specific activity of radium-226, thorium-232, potassium-40 and caesium-137 radionuclides was performed by using High-Purity Germanium (HPGe) γ-ray spectrometry, together with the estimation of several indexes developed to evaluate the radiological risk for the population related to radiation exposure, i.e., the alpha index (Iα), the radium equivalent activity (Raeq), the absorbed γ-dose rate (D) and the annual effective dose equivalent outdoor (AEDEout) and indoor (AEDEin). Moreover, measurements of the average heavy metals (arsenic, cadmium, copper, mercury, nickel, lead, antimony, thallium and zinc) concentrations in the analyzed sample were performed by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Furthermore, with the aim to investigate any possible chemical pollution, the Enrichment Factor (EF), Geo-accumulation Index (Igeo), Contamination Factor (CF) and Pollution Load Index (PLI) were assessed. Finally, the identification of the source of the aforementioned radioisotopes of natural origin was carried out by X-ray diffraction (XRD), thus identifying the major mineralogical phases present in the investigated basalt aggregate for concrete.

Abstract The theoretical limit of the color‐change sensitivity of a composite resin dosimeter film based on 6‐nitro BIPS/BaFCl : Eu2+/polystyrene under X‐ray exposure has been estimated. Each photophysical and photochemical process occurring inside the composite resin dosimeter was quantitatively determined, and the obtained values were used to estimate the theoretical limit of the color‐change sensitivity for the composite resin dosimeter. The values obtained were 70.6 % for the X‐ray absorption efficiency, 13 % for the fluorescence quantum yield, 73.5 % for the UV absorption efficiency and 37.6 % for the photochemical quantum yield. Assuming that the figure‐of‐merit is their product, its value is estimated to be 2.5 %, which contributes to the chromaticity difference and leads to a color‐change sensitivity of 100 mGy. The figure‐of‐merit of a structurally optimized composite dosimeter was estimated to be 1.9 times that of the dosimeter without structural optimization, which showed a sensitivity of 100 mGy. We predicted that the structurally optimized composite resin dosimeter film, which eliminates optical losses due to the structure, will be able to detect X‐ray exposure doses on the order of approximately 28 mGy.

This work presents a physical, mechanical, durability, leaching, and radiological assay of three wastes (egg and scallop shells and olive pomace ash) as road-base binders. Two different waste/Portland-cement ratios (7.5/92.5 and 80/20) were studied. Density and compressive strength decreased when different wastes were added in every proportion. Additions of 7.5% of both shells reduce the density to about 2.5% and the compressive strength to 20%, while 80% reduces the density to 20% and the compressive strength to 90%, while the addition of biomass fly ash decreases the density and compressive strength in a higher proportion than shells. The durability against acid attack is increased when the three wastes are used, and this increase is higher when the waste dosage is increased (up to 15 times more when 80% biomass ash is used). With respect to leaching, scallop and eggshells can be used as a component of hydraulic road binder, but olive pomace ash presents leaching values higher than the limits of different regulations (Se, Pb, Ni, Mo, Cu, and As). From a radiological perspective, all road-base binders present an activity concentration index lower than 1, except when olive pomace ash was used, and the binders showed higher values of 40K due to the high potassium content of fly ash.

In this article, the assessment of the radioactivity content in bovine meat from the Calabria region, Southern Italy, was performed. For this purpose, High Purity Germanium (HPGe) gamma spectrometry measurements were carried out in order to investigate any possible radioactive contamination by natural (40K) and anthropogenic (137Cs) radionuclides. Experimental mean values were found to be in the range from (78.9 ± 10.5) Bq kg−1 to (88.2 ± 12.5) Bq kg−1 for 40K and lower than the minimum detectable activity (MDA) in all cases for 137Cs, respectively. Moreover, any possible radiological health risk was also estimated, by calculating the total annual effective dose due to the ingestion of bovine meat by adult members of the population and by comparing it with the total natural radioactivity value (external + internal) for humans. Obtained values are in the range from 10.3 µSv y−1 to 11.5 µSv y−1, several orders of magnitude lower than the value of the total exposure to natural radioactivity for human beings, i.e., 2.4 mSv y−1. It is worth noting that the used approach could be used, in principle, for the evaluation of the radiological risk due to the presence of radionuclides in a large variety of food samples of particular interest, and thus it can constitute a guideline for investigations focused on the monitoring of food quality.

The pioneering works of E. Rutherford related to radioactivity and nuclear science were contributions to physics, but they also had important implications for chemistry. Thus, in his early study of the 'emanation' liberated from thorium and radium Rutherford showed that it was a new element (radon). His theory of radioactive decay sounded the death knell over the old chemical dogma of the immutability of atoms. Likewise, the discovery of the nuclear atom in 1911 led to a new understanding of the periodic system soon developed by N. Bohr, H. Moseley and others. The first artificial transmutation of an element in 1919 was later followed by proton- and deuteron-induced transformations from which Rutherford suggested the existence of mass-3 isotopes of hydrogen and helium. In addition, he was the first to suggest that the still hypothetical neutron might be used as a projectile in nuclear reactions. [ABSTRACT FROM AUTHOR]

This study was carried out to determine the presence of the main radionuclides from natural and artificial radioactivity in the soil of Kosovo, using gamma-ray spectroscopy. The mean activity concentration for Ra-226, Th-232, K-40, and Cs-137 was 22.32 ± 1.41, 22.14 ± 1.31, 358.16 ± 8.85, and 12.94 ± 0.44 Bq/kg, respectively. Radium equivalent activity ranged from 47 to 100 Bq/kg. The mean of calculated values for the gamma index (Iγ), external hazard index (Hex), absorbed dose rate (ADR), annual gonadal dose rate (AGDE), annual effective dose rate (AEDE), and excess lifetime cancer risk (ELCR) were 0.61, 0.22, 40 nGy/h, 275 µSv/year, 49 µSv/year, and 170, respectively. In conclusion, the radiological parameters arising from the soil samples of Kosovo belong to the normal range of radionuclides, compared to those compiled by UNSCEAR from worldwide reports; therefore, health hazards are insignificant.

Chemistry has been a pivotal part of scientific discovery and human life for centuries. This essay argues that chemical terms, tropes, figures, appeals, and narratives serve as powerful rhetorical features of public discourse. From affinities and atoms to dark matter and radioactivity, chemical rhetoric fulfills a central organizing function in contemporary society and shapes how people deliberate and delineate their identities, relationships, and communities. The present research demarcates chemical rhetoric as a form of nonexpert communication, and explicates its association with chemistry's disciplinary history, as well as with technical chemical language's grounding in key focal concepts. More specifically, it maps out a framework for defining and theorizing chemical rhetoric through three, interconnected lenses: historical–ecological, conceptual articulation, and vernacular. The overarching goal in this essay is to create an infrastructure for investigating chemistry's longitudinal circulation and emergence as a shared public vocabulary. [ABSTRACT FROM AUTHOR]

Destructive and non-destructive analysis techniques were used to establish a radiological baseline around the Barakah Nuclear Power Plant area in Abu Dhabi, United Arab Emirates. The natural radioactivity concentrations of 238U (226Ra), 232Th and 40K were measured for shore, soil and bottom sediment samples, using gamma spectrometry with a high-purity germanium (HPGe) detector. Alpha spectrometry was used to measure the 234U/238U ratio for some selected samples using a silicon surface-barrier detector. The measured gamma activity concentrations in shore samples are much lower compared to those in soil and bottom samples. The average activity concentrations of 238U (226Ra) are 4.43 ± 1.12, 13.54 ± 4.16 and 4.73 ± 3.01 Bq/kg in shore, soil and bottom sediment samples, respectively. The corresponding values for 232Th are 1.68 ± 0.49, 8.31 ± 3.87 and 1.83 ± 1.67 Bq/kg, and those for 40K, are 106.30 ± 50.68, 349.72 ± 107.16 and 105.23 ± 130.14 Bq/kg. The 234U/238U activity ratios span a wide range from 0.59 to 2.24, indicating a system where the daughter/parent is out of secular radioactive equilibrium. The hazard parameters, radium equivalent and absorbed dose rates, showed low levels compared to the world average level reported by the UNSCEAR in 2000. The estimated activity concentrations in this study were lower than the world average values and lower than the levels reported in nearby countries.

The natural (40K) and anthropogenic (137Cs) radioactivity concentration in four different typologies of early childhood (up to two years old) foods, i.e., homogenized fruit, homogenized meat, childhood biscuits and baby pasta, produced in Italy and sold in Italian large retailers, was investigated through High Purity Germanium (HPGe) gamma spectrometry. The present study is carried out with the aim to: (i) evaluate the background levels of the investigated radionuclides in the analyzed early childhood foods, (ii) identify whether the twenty analyzed samples were appropriate for infant consumption and (iii) contribute to construct a database on the radioactivity of early childhood foods sold in Italy.

Radioactivity was measured in a micellar gel dosimeter, a polymer gel dosimeter, and water was irradiated by carbon ion beams at various beam energy conditions. Monte Carlo simulation was also performed to estimate the radioactivity. Short-lived positron-emitting nuclides were observed immediately after irradiation, but they decayed rapidly into the background. At 24 h post-irradiation, the dominant measured radioactivity was of 7Be. The simulation also showed minor activity of 24Na and 3H; however, they were not experimentally observed. The measured radioactivity was independent of the type of gel dosimeter under all irradiation conditions, suggesting that the radioactivity was induced by the interaction of carbon ions with water (the main component of the gel dosimeters). The ratio between the simulated and measured radioactivity was within 0.9–1.5. The activity concentration of 7Be was found to be less than 1/10 of the value derived using the exemption concept proposed by the International Atomic Energy Agency. This result should be applicable to irradiated gel dosimeters containing mainly water and 0–4 wt.% C and 0–1.7 wt.% N.

The radiological quality of drinking water is directly associated with the health of the population. Indeed, it is well known that the presence of radionuclides in drinking water constitutes a health risk for humans because the consumption of such water increases the likelihood of incurring cancer. For this reason, all the studies aimed at developing new methodologies for the qualitative and quantitative analysis of the radioisotopic composition of drinking water are absolutely desired by the international scientific community, as well as by the institutes that deal with the protection of public health. In this paper, a new methodological approach was developed for the evaluation of the 238U content in drinking water. A sample coming from Paola, Calabria region, southern Italy, was taken as a case study. The assessment was performed by using High Purity Germanium (HPGe) gamma-ray spectrometry, with the aim of quantifying the specific activity of the 234mPa radioisotope after a preconcentration procedure, and thus to assess the activity concentration of 238U, in the hypothesis of the secular radioactive equilibrium between it and its daughter. The obtained results were validated through the comparison with the 238U (µg/L) concentration as measured with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).

When Dmitri Mendeleev laid out his ordered grid of the then-known elements in 1869, he could not have predicted the overwhelming and all-encompassing effect that his idea would have on scientific theory for the next 150 years. Nevertheless, he knew, presciently and from the start that he had conceived and laid claim to a powerful predictive tool that would bring some kind of order to a seemingly random set of fundamental substances. It is not within the scope of this paper to detail how the thought currents of his day were converging, little by little, on the realization that the universe was an intrinsically ordered one, nor is it our purpose to award to Mendeleev the title of sole “discoverer” of the periodic system. We wish merely to point out that he now occupies a well-deserved place within the system under the title of “mendelevium,” element 101, and that, by this attribution, he belongs to a special “family,” the actinides. How this family was uncovered, grew, and developed is the topic of this essay.

A new radiological risk containment procedure, developed to manage the radiological risk in potentially contaminated areas, is presented here. This new methodological approach, systematically employed in sampling and site inspection activities in unknown areas from an environmental point of view, allowed the discovery of eight 226Ra orphan sources buried under the road surface, in a good state of conservation, in an industrial area of the Calabrian territory, southern Italy, and they are reported here as a case study. For workers performing sampling activities in areas for which information regarding the possible presence of contaminated material is missing, an in situ radiometric check is usually carried out as a potential radiological risk prevention, by measuring the levels of environmental radioactivity. Other than this, the procedure described in this article includes, as novelty, a series of progressive operations never carried out before all together for outdoor activities: the assessment of the presence (if any) of hot spots by recording radiometric anomalies, outdoor gamma spectrometry measurements in order to identify the radionuclides generating those anomalies, the sources unearthing activities, the management of the material found and the application of a risk containment protocol.

Abstract There is considerable interest in the chemical composition of smokeless tobacco products (STPs), owing to health concerns associated with their use. Previous studies have documented levels of 210Po, 210Pb and uranium in STP samples. Here, the levels of 13 α-particle and 15 β-radiation emitting radionuclides have been measured in a broad and representative range of contemporary STPs commercially available in the United States and Sweden. For each radionuclide, the level of radioactivity and calculated mass per gram of STP are reported. The results indicate that, among 34 Swedish snus and 44 US STPs, a more complex radionuclide content exists than previously reported for these products. Of the 28 radionuclides examined, 13 were detected and quantified in one or more STPs. The most frequently identified radionuclides in these STPs were 40K, 14C, 210Po and 226Ra. Over half the STPs also contained 228Th, and an additional 8 radionuclides were identified in a small number of STPs. The presence of 14C, 3H and 230Th are reported in tobacco for the first time. The activity of β-emitters was much greater than those of α-emitters, and the β-emitter 40K was present in the STPs with both the greatest radioactivity and mass concentrations. Since the three radionuclides included in the FDA’s HPHC list were either not detected (235U), identified in only three of 78 samples (238U), and/or had activity levels over fifty times lower than that of 40K (210Po, 238U), there may be a rationale for reconsidering the radionuclides currently included in the FDA HPHC list, particularly with respect to 40K. Using a model of the physical and biological compartments which must be considered to estimate the exposure of STP users to radionuclides, we conclude that exposure from α-emitters may be minimal to STP users, but 40K in particular may expose the oral cavities of STP users to β-radiation. Although a more comprehensive picture of the radioisotope content of STPs has emerged from this study, epidemiological evidence suggests that the levels of radionuclides measured in this study appear unlikely to present significant risks to STP users.

Technetium-99m labeled radiopharmaceutical is commonly used in nuclear medicines as a diagnostic agent, by mixing the sterile kit with Tc-99m. Manufacturing of kits requires an aseptic facility which need to be well designed and maintained according to cGMP, since mostly kits can not be terminally sterilized. Radiopharmaceuticals as pharmaceuticals containing radionuclide is assumed to have an autosterilization property, but correlation between radioactivity and capability of killing microorganisms has to be studied so far. The aim of this study is to investigate the effect of radioactivity on the autosterilization process of radiopharmaceuticals. The study was carried out by adding Tc-99m of various radioactivity into non-sterile tetrofosmin kits, then the samples were tested for sterility. Sterile tetrofosmin kit and non-sterile kit with no Tc-99m added will be used as a negative control and positive control respectively. The sterility was tested using standard direct inoculation method, by inoculating samples in culture media for both bacteria and fungi and observing qualitatively within 14 days. The results showed that the samples with radioactivity of 1, 3 and 5 mCi changed the clarity of the media to turbid, conformed with the performance of positive controls but samples with radioactivity of 10 mCi and 20 mCi did not change the clarity of the media, conformed with the performance of negative control, indicating neither growth of bacteria nor fungi. It is concluded that Tc-99m behaves as an autosterilizing agent at certain radioactivity. Therefore the preparation of Tc-99m radiopharmaceutical can be considered as terminal sterilization rather than aseptic preparation.

[18F]T807 is a potent tau protein imaging agent. In order to fulfill the demand from preclinical and clinical studies, we developed an automated one-pot two-step synthesis of this potent tau imaging agent and studied its stability, and dosimetry in mice and monkeys. We also conducted a preliminary study of this imaging agent in humans. Using this one-pot two-step method, the radiochemical yield (RCY) of [18F]T807 was 20.5 ± 6.1% (n = 15) at the end of bombardment (EOB) in a synthesis time of 70±5 min. The chemical and radiochemical purities were >90% and the specific activities were 151 ± 52 GBq/μmol. The quality of [18F]T807 synthesized by this method met the U.S. Pharmacopoeia (USP) criteria. The stability test showed that the [18F]T807 injection was stable at room temperature for up to 4 h after the end of synthesis (EOS). The estimated effective dose of the [18F]T807 injection extrapolated from monkeys was 19 μSv/MBq (n = 2), while the estimated effective doses of the [18F]T807 injection extrapolated from fasted and non-fasted mice were 123 ± 27 (n = 3) and 94 ± 19 (n = 4) μSv/MBq, respectively. This one-pot two-step automated method produced the [18F]T807 injection with high reproducibility and high quality. PET imaging and radiation dosimetry evaluation in mice and Formosan rock monkeys suggested that the [18F]T807 injection synthesized by this method is suitable for use in human PET imaging studies. Thus, this method could fulfill the demand for the [18F]T807 injection in both preclinical and clinical studies of tauopathies, especially for nearby study sites without cyclotrons. [ABSTRACT FROM AUTHOR]

Previously, we have reported that spherical particles (SPs) are formed by the thermal remodeling of rigid helical virions of native tobacco mosaic virus (TMV) at 94°C. SPs have remarkable features: stability, unique adsorption properties and immunostimulation potential. Here we performed a comparative study of the amino acid composition of the SPs and virions surface to characterize their properties and take an important step to understanding the structure of SPs. The results of tritium planigraphy showed that thermal transformation of TMV leads to a significant increase in tritium label incorporation into the following sites of SPs protein: 41–71 а.a. and 93–122 a.a. At the same time, there was a decrease in tritium label incorporation into the N- and C- terminal region (1–15 a.a., 142–158 a.a). The use of complementary physico-chemical methods allowed us to carry out a detailed structural analysis of the surface and to determine the most likely surface areas of SPs. The obtained data make it possible to consider viral protein thermal rearrangements, and to open new opportunities for biologically active complex design using information about SPs surface amino acid composition and methods of non-specific adsorption and bioconjugation. [ABSTRACT FROM AUTHOR]

Background: Although a 3-arm DOTA construct, which has three carboxylic acids, h has been applied for conjugation to many peptides, we investigated if a 4-arm DOTA construct conjugated to peptides improves chemical properties for melanoma imaging of the melanocortin 1 receptor compared to 3-arm DOTA-conjugated peptides. Methods: Specific activities, radiolabeling efficiencies, and partition coefficients were evaluated using 111In-labeled 3-arm and 4-arm DOTA-α-melanocyte-stimulating hormone (MSH). For assessment of MC1-R affinity and accumulation in tumor cells in vitro, B16-F1 melanoma and/or 4T1 breast cancer cells were incubated with 111In-labeled 3-arm and 4-arm DOTA-α-MSH with and without α-MSH as a substrate. The stability was evaluated using mouse liver homogenates and plasma. Biological distribution and whole-body single photon emission computed tomography imaging of 111In-labeled 3-arm and 4-arm DOTA-α-MSH were obtained using B16-F1 melanoma-bearing mice. Results: Specific activities and radiolabeling efficiencies of both radiotracers were about 1.2 MBq/nM and 90–95%, respectively. The partition coefficients were −0.28 ± 0.03 for 111In-labeled 3-arm DOTA-α-MSH and −0.13 ± 0.04 for 111In-labeled 4-arm DOTA-α-MSH. Although accumulation was significantly inhibited by α-MSH in B16-F1 cells, the inhibition rate of 111In-labeled 4-arm DOTA-α-MSH was lower than that of 111In-labeled 3-arm DOTA-α-MSH. 111In-labeled 4-arm DOTA-α-MSH was taken up early into B16-F1 cells and showed higher accumulation than 111In-labeled 3-arm DOTA-α-MSH after 10 min of incubation. Although these stabilities were relatively high, the stability of 111In-labeled 4-arm DOTA-α-MSH was higher than that of 111In-labeled 3-arm DOTA-α-MSH. Regarding biological distribution, 111In-labeled 4-arm DOTA-α-MSH showed significantly lower average renal accumulation (1.38-fold) and significantly higher average melanoma accumulation (1.32-fold) than 111In-labeled 3-arm DOTA-α-MSH at all acquisition times. 111In-labeled 4-arm DOTA-α-MSH showed significantly higher melanoma-to-kidney, melanoma-to-blood, and melanoma-to-muscle ratios than 111In-labeled 3-arm DOTA-α-MSH. Conclusions: The 4-arm DOTA construct has better chemical properties for peptide radiotracers than the 3-arm DOTA construct. [ABSTRACT FROM AUTHOR]

Imaging was conducted using an electron tracking-Compton camera (ETCC), which measures γ-rays with energies in the range of 200–900 keV from 95mTc. 95mTc was produced by the 95Mo(p, n)95mTc reaction on a 95Mo-enriched target. A method for recycling 95Mo-enriched molybdenum trioxide was employed, and the recycled yield of 95Mo was 70%-90%. Images were obtained with the gate of three energies. The results showed that the spatial resolution increases with increasing γ-ray energy, and suggested that the ETCC with high-energy γ-ray emitters such as 95mTc is useful for the medical imaging of deep tissue and organs in the human body. [ABSTRACT FROM AUTHOR]

This study aims to determine the knowledge levels of pre-service science teachers about radioactivity. A knowledge test was administered to 56 pre-service science teachers participated in the General Chemistry I course in the fall semester of 2014-15 academic year. Papers derived from the pre-service science teachers were read and evaluated, and the responses were classified as “accurate", "misconception", "wrong" and "empty" categories for open-ended questions and the responses to the multiple-choice questions were classified as "right" and "wrong". The pre-service science teachers’ correct response rates were between 9 % (definition of “nuclear radiation” concept, question 15) and 86 % (radioactivity uses, question 14) in open-ended questions whereas in multiple choice questions the ratio of correct answers ranged from 5 % (concept definition and nuclear reactions, questions 21, 23 and 33) to 98 % (sample of concept, question 20). Students hold misconceptions on the radioactivity, warning picture, nuclear power plant (questions 1, 13, and 16); isotopes (question 4); natural and artificial nucleus reaction (question 6); age of the rocks (question 8); atomic bomb (question 10); hydrogen bomb (question 11) and core irradiation (question 15).

Atmospheric methane is rapidly lost when it enters humid subterranean critical and vadose zones (e.g., air in soils and caves). Because methane is a source of carbon and energy, it can be consumed by methanotrophic methane-oxidizing bacteria. As an additional subterranean sink, it has been hypothesized that methane is oxidized by natural radioactivity-induced radiolysis that produces energetic ions and radicals, which then trigger abiotic oxidation and consumption of methane within a few hours. Using controlled laboratory experiments, we tested whether radiolysis could rapidly oxidize methane in sealed air with different relative humidities while being exposed to elevated levels of radiation (more than 535 kBq m-3) from radon isotopes 222Rn and 220Rn (i.e., thoron). We found no evidence that radiolysis contributed to methane oxidation. In contrast, we observed the rapid loss of methane when moist soil was added to the same apparatus in the absence of elevated radon abundance. Together, our findings are consistent with the view that methane oxidizing bacteria are responsible for the widespread observations of methane depletion in subterranean environments. Further studies are needed on the ability of microbes to consume trace amounts of methane in poorly ventilated caves, even though the trophic and energetic benefits become marginal at very low partial pressures of methane. [ABSTRACT FROM AUTHOR]

PIKfyve, an evolutionarily conserved kinase synthesizing PtdIns5P and PtdIns(3,5)P2, is crucial for mammalian cell proliferation and viability. Accordingly, PIKfyve inhibitors are now in clinical trials as anti-cancer drugs. Among those, apilimod is the most promising, yet its potency to inhibit PIKfyve and affect endomembrane homeostasis is only partially characterized. We demonstrate here for the first time that apilimod powerfully inhibited in vitro synthesis of PtdIns5P along with that of PtdIns(3,5)P2. HPLC-based resolution of intracellular phosphoinositides (PIs) revealed that apilimod triggered a marked reduction of both lipids in the context of intact cells. Notably, there was also a profound rise in PtdIns3P resulting from arrested PtdIns3P consumption for PtdIns(3,5)P2 synthesis. As typical for PIKfyve inhibition and the concomitant PtdIns(3,5)P2 reduction, apilimod induced the appearance of dilated endomembrane structures in the form of large translucent cytoplasmic vacuoles. Remarkably, bafilomycin A1 (BafA1) fully reversed the aberrant cell phenotype back to normal and completely precluded the appearance of cytoplasmic vacuoles when added prior to apilimod. Inspection of the PI profiles ruled out restoration of the reduced PtdIns(3,5)P2 pool as a molecular mechanism underlying BafA1 rescue. Rather, we found that BafA1 markedly attenuated the PtdIns3P elevation under PIKfyve inhibition. This was accompanied by profoundly decreased endosomal recruitment of fusogenic EEA1. Together, our data demonstrate that apilimod inhibits not only PtdIns(3,5)P2 but also PtdIns5P synthesis and that the cytoplasmic vacuolization triggered by the inhibitor is precluded or reversed by BafA1 through a mechanism associated, in part, with reduction in both PtdIns3P levels and EEA1 membrane recruitment. [ABSTRACT FROM AUTHOR]