Impact of 900 MHz electromagnetic field exposure on main male reproductive hormone levels: a Rattus norvegicus model

This work analyzes the effects of radiofrequency-electromagnetic field (RF-EMF) exposure on the reproductive system of male rats, assessed by measuring circulating levels of FSH, LH, inhibin B, activin B, prolactin, and testosterone. Twenty adult male Sprague–Dawley rats (180?±?10 g) were exposed to 900 MHz RF-EMF in four equal separated groups. The duration of exposure was 1, 2, and 4 h/day over a period of 30 days and sham-exposed animals were kept under the same environmental conditions as the exposed group except with no RF-EMF exposure. Before the exposure, at 15 and 30 days of exposure, determination of the abovementioned hormone levels was performed using ELISA. At the end of the experiment, FSH and LH values of the long time exposure (LTE) group were significantly higher than the sham-exposed group (p?p?p?相似文献   

Analysis of global DNA methylation changes in human keratinocytes immediately following exposure to a 900 MHz radiofrequency field

The increasing use of nonionizing radiofrequency electromagnetic fields (RF-EMFs) in a wide range of technologies necessitates studies to further understanding of biological effects from exposures to such forms of electromagnetic fields. While previous studies have described mechanisms for cellular changes occurring following exposure to low-intensity RF-EMFs, the role of molecular epigenetics has not been thoroughly investigated. Specifically unresolved is the effect of RF-EMFs on deoxyribonucleic acid (DNA) methylation, which is a powerful epigenetic process, used by cells to regulate gene expression. DNA methylation is dynamic and can be rapidly triggered in response to external stimuli such as exposure to RF-EMFs. In the present study, we performed a global analysis of DNA methylation patterns in human keratinocytes exposed to 900 MHz RF-EMFs for 1 h at a low dose rate (estimated mean specific absorption rate (SAR) < 10 mW/kg). We used a custom system to allow stable exposure of cell cultures to RF-EMFs under biologically relevant conditions (37 °C, 5% CO₂, 95% humidity). We performed whole genome bisulfite sequencing directly following RF-EMF exposure to examine the immediate changes in DNA methylation patterns and identify early differentially methylated genes in RF-EMF-exposed keratinocytes. By correlating global gene expression to whole genome bisulfite sequencing, we identified six common targets that were both differentially methylated and differentially expressed in response to RF-EMF exposure. The results highlight a potential epigenetic role in the cellular response to RF-EMFs. Particularly, the six identified targets may potentially be developed as epigenetic biomarkers for immediate responses to RF-EMF exposure. Bioelectromagnetics. 1–13, © 2023 Bioelectromagnetics Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.     

Post-continuous whole body exposure of rabbits to 650 MHz electromagnetic fields: effects on liver, spleen, and brain

This study deals with the effects of post (12 or 18 months) whole body continuous (2 years) exposure of rabbits to 650 MHz electromagnetic fields (EMF) that are characteristic of those produced by broadcasting stations, on body weight and body mass, on the morphology of liver, spleen and brain, and on apoptosis rates and glycogen distribution in the liver. Two groups of rabbits were continuously exposed for 2 years to EMF of 650 MHz followed by 12 months (group 1) or 18 months (group 2) of post-exposure; a third group (group 3) was sham exposed. It was shown that the changes in apoptosis rates were conditional during the time of exposure, but not on a specific organ and that the whole body continuous exposure gave rise to modifications whose types and intensities were related to the time of post-exposure (12 or 18 months, respectively), the type of organ, and the individual animal. A number of effects were observed only in group 1, and not in group 2, which suggests some kind of adaptive response or of long-term recovery in the rabbits following continuous exposure to 650 MHz EMF.     

DNA damage in thymocytes of mice after exposure of the whole body to combined action of cadmium ions and γ radiation

The effect of combined action of cadmium chloride at a dose of 0.5 mg/kg of body weight and γ-radiation of 1 Gy on induction of DNA damage in thymocytes and the total number of cells in the thymus of mice was studied. We found that injection of CdCl₂ 0.5 h prior to irradiation decreased the number of single-strand DNA breaks and the number of alkali-labile sites in thymocytes 48 h after irradiation as compared to the γ-radiation effect only. This effect was associated with a strong decrease in the total number of thymocytes in this organ as compared to the action of cadmium ions and γ radiation separately. This masked the general genotoxic effect of combined treatment and created an illusion of a radioprotective effect of cadmium ions. Injection of cadmium chloride into mice 24 h prior to irradiation was followed by an additive increase in the number of the single-strand DNA breaks and the number of alkali-labile sites in thymocytes as compared to the respective controls such as the separate effects of cadmium ions and irradiation. We revealed a simultaneous decrease in the part of DNA tightly bound to proteins, i.e., DNA-protein cross-links as compared to the effect of γ-radiation only. We did not observe any statistically significant changes in the total number of thymocytes as compared to the separate effects of cadmium ions and irradiation. Thus, our data show that exposure of murine thymocytes to combined action of cadmium ions and γ-radiation at the doses and with the methods of treatment used induced additive effects but not antagonistic effects or protection against radiation.     

Ginger extract mitigates ethanol-induced changes of alpha and beta – myosin heavy chain isoforms gene expression and oxidative stress in the heart of male wistar rats

The association between ethanol consumption and heart abnormalities, such as chamber dilation, myocyte damage, ventricular hypertrophy, and hypertension is well known. However, underlying molecular mediators involved in ethanol-induced heart abnormalities remain elusive. The aim of this study was to investigate the effect of chronic ethanol exposure on alpha and beta – myosin heavy chain (MHC) isoforms gene expression transition and oxidative stress in rats’ heart. It was also planned to find out whether ginger extract mitigated the abnormalities induced by ethanol in rats’ heart. Male wistar rats were divided into three groups of eight animals as follows: Control, ethanol, and ginger extract treated ethanolic (GETE) groups. After six weeks of treatment, the results revealed a significant increase in the β-MHC gene expression, 8- OHdG amount, and NADPH oxidase level. Furthermore, a significant decrease in the ratio of α-MHC/β-MHC gene expression to the amount of paraoxonase enzyme in the ethanol group compared to the control group was found. The consumption of Ginger extract along with ethanol ameliorated the changes in MHC isoforms gene expression and reduced the elevated amount of 8-OHdG and NADPH oxidase. Moreover, compared to the consumption of ethanol alone, it increased the paraoxonase level significantly.These findings indicate that ethanol-induced heart abnormalities may in part be associated with MHC isoforms changes mediated by oxidative stress, and that these effects can be alleviated by using ginger extract as an antioxidant molecule.     

Changes in reproductive organs of male rats on exposure to hypoxia (6,060 m) and cold (−5°C). effects of cold-induced cryptorchidism

Adult male rats were exposed to a combination of hypoxia (6,060 m) and cold (–5°C) for 21 days. In one group the left testis was restricted to the scrotum by a suture to the inguinal canal. After exposure, body weight was reduced and the reproductive organs (testis, epididymis and vas deferens) were reduced in weight and showed atrophic changes. There was deterioration in sperm quality. The above changes increased as the exposure was extended from 7 days to 21 days. Cold appears to aggravate the effects of hypoxia on the male reproductive organs. The damage to these organs was greater when cold-induced cryptorchidism was allowed to occur during exposure than when it was avoided. The secretory activity of the epididymis was reduced after exposure. The significance of changes in the biochemical composition of these organs is discussed.     

Does a trade‐off between current reproductive success and survival affect the honesty of male signalling in species with male parental care?

Recent theory predicted that male advertisement will reliably signal investment in paternal care in species where offspring survival requires paternal care and males allocate resources between advertisement and care. However, the predicted relationship between care and advertisement depended on the marginal gains from investment in current reproductive traits. Life history theory suggests that these fitness gains are also subject to a trade‐off between current and future reproduction. Here, we investigate whether male signalling remains a reliable indicator of parental care when males allocate resources between current advertisement, paternal care and survival to future reproduction. We find that advertisement is predicted to remain a reliable signal of male care but that advertisement may cease to reliably indicate male quality because low‐quality males are predicted to invest in current reproduction, whereas higher‐quality males are able to invest in both current reproduction and survival to future reproduction.     

Flavonoids protect against oxidative damage to LDL in vitro: use in selection of a flavonoid rich diet and relevance to LDL oxidation resistance ex vivo?

The ability of a range of dietary flavonoids to inhibit low-density lipoprotein (LDL) oxidation in vitro was tested using a number of different methods to assess oxidative damage to LDL. Overall quercetin was the most effective inhibitor of oxidative damage to LDL in vitro. On this basis, a diet enriched with onions and black tea was selected for a dietary intervention study that compared the effect on the Cu²⁺ ion-stimulated lag-time of LDL oxidation ex vivo in healthy human subjects of a high flavonoid diet compared with a low flavonoid diet. No significant difference was found in the Cu²⁺ ion-stimulated lag-time of LDL oxidation ex vivo between the high flavonoid and low flavonoid dietary treatments (48 ± 1.6 min compared to 49 ± 2.1 min).     

Influence of chronic exposure to low doses of γ-radiation and <Superscript>90</Superscript>Sr on the level of DNA breaks and cell sensitivity to hydrogen peroxide in the mouse spleen

Using comet assay, a statistically significant increase (p < 0.05) in the level of DNA breaks in spleen cells was revealed in male CBA/lac mice exposed to γ-radiation (1.7 mGy/day) or ⁹⁰Sr (150–250 Bq/day) for 210 days. The level of DNA breaks also increased under combined exposure to both γ-radiation and ⁹⁰Sr (p < 0.05), but to a lesser degree than under exposure to each of these factors alone. Upon additional in vitro treatment of spleen cells with hydrogen peroxide, the relative increase in the level of DNA breaks was smaller in cells of irradiated mice than in the control. The ratio of the level of DNA breaks after hydrogen peroxide treatment to that before this treatment in control mice was 4.2 ± 0.9, compared to 1.4 ± 0.6 in γ-irradiated mice, 1.9 ± 0.8 in ⁹⁰Sr-irradiated mice, and 2.3 ± 0.8 in mice exposed to both γ- and ⁹⁰Sr-irradiation.     

Can oxidative DNA damage be used as a biomarker of cancer risk in humans? Problems, resolutions and preliminary results from nutritional supplementation studies

Damage to DNA by oxygen radicals and other reactive oxygen/nitrogen/chlorine species occurs in vivo despite the presence of multiple antioxidant defence and repair systems. Such damage is thought to make a significant contribution to the age-related development of cancer. Modulation of oxidative DNA damage by diet thus constitutes a "biomarker" putatively predictive of the effect of diet on cancer incidence, provided that DNA damage can be accurately quantitated by validated methods. Current issues addressed in this article include the problems of artifactual DNA oxidation during isolation and analysis, the relative merits of different analytical methods, the advantages and disadvantages of relying on measurement of 8-hydroxydeoxyguanosine (8OHdG, 8-oxodG) as an index of oxidative DNA damage, and the limited data that are so far available on how diet can affect "steady-state" levels of oxidative DNA damage in humans. It appears that such damage can be modulated by vegetable intake, although the effects of vegetables may be mediated by components different from the "classical" antioxidants vitamin C, alpha-tocopherol and beta-carotene.     

α-lipoic acid ameliorates inflammation state and oxidative stress by reducing the content of bioactive lipid derivatives in the left ventricle of rats fed a high-fat diet

Lipid mediators derived from arachidonic acid (AA) are implicated with the occurrence of inflammation and oxidative stress. The current knowledge of AA metabolism focuses on searching for the therapeutic strategy to subvert affected AA metabolism. The aim of our study was to evaluate the potential protective effect of chronic α-lipoic acid (α-LA) supplementation on myocardial inflammation state and oxidative stress in obesity-related cardiovascular dysfunction. The experiment was carried out on male Wistar rats receiving a standard or a high-fat diets with intragastric α-LA administration for 8 weeks. Plasma and myocardial AA concentrations were determined using the gas-liquid chromatography (GLC). The Western blot technique was used to examine the expression of proteins from the inflammatory pathway. The content of selected cytokines, inflammatory mediators, and oxidative stress indicators was detected by the ELISA, colorimetric, and multiplex assay kits. Our results revealed that α-LA caused a notable reduction in AA content, mainly in the phospholipid fraction with a simultaneous diminishment in the synthesis of pro-inflammatory mediators, i.e., prostaglandin E2, leukotrienes B4 and C4 by decreasing the expression of COX-2 and 5-LOX. α-LA also augmented the level of antioxidative SOD2 and GSH and decreased the level of lipid peroxidation products, which improved oxidative system impairment in the left ventricle tissue. The data clearly showed that α-lipoic acid has a significant role in inflammation and oxidative stress development ameliorating the risk of cardiac obesity induced by high-fat feeding.     

Protective effects of the volatile oil of Nigella sativa seeds on β-cell damage in streptozotocin-induced diabetic rats: a light and electron microscopic study

The aim of this study was to evaluate the possible protective effects of the volatile oil of Nigella sativa (NS) seeds on insulin immunoreactivity and ultrastructural changes of pancreatic β-cells in STZ-induced diabetic rats. STZ was injected intraperitoneally at a single dose of 50 mg/kg to induce diabetes. The rats in NS treated groups were given NS (0.2 ml/kg) once a day orally for 4 weeks starting 3 days prior to STZ injection. To date, no ultrastructural changes of pancreatic β-cells in STZ induced diabetic rats by NS treatment have been reported. Islet cell degeneration and weak insulin immunohistochemical staining was observed in rats with STZ-induced diabetes. Increased intensity of staining for insulin, and preservation of β-cell numbers were apparent in the NS-treated diabetic rats. The protective effect of NS on STZ-diabetic rats was evident by a moderate increase in the lowered secretory vesicles with granules and also slight destruction with loss of cristae within the mitochondria of β-cell when compared to control rats. These findings suggest that NS treatment exerts a therapeutic protective effect in diabetes by decreasing morphological changes and preserving pancreatic β-cell integrity. Consequently, NS may be clinically useful for protecting β-cells against oxidative stress.     

Does fire affect the temporal pattern of trophic resource supply to pollinators and seed-dispersing frugivores in a Brazilian savanna community?

In tropical savannas, such as the campo cerrado in Brazil, fire plays an important role, affecting plant species’ life history. Since fire has the potential to modify the structure of savanna communities as a whole, it is expected that it may influence the resource supply for mutualists by altering the pattern of investment in sexual reproduction. We used an experimental approach to test if fire alters trophic resource availability to pollinators (nectar, pollen, and oil) and seed-dispersing frugivores (fleshy fruits) by altering the seasonality of reproductive phenophases in a savanna community. We sampled all individuals of 60 species that were common to both control and experimental fire treatments. Each month we recorded the number of reproductive individuals to test whether fire affected the temporal resource offered by the plant assemblage as a whole, and by each specific plant group supporting distinct groups of pollinators and seed-dispersing frugivores. We noticed that fire advanced the nectar, pollen, and fleshy fruit offered by the whole assemblage. Additionally, fire affected the temporal pattern of nectar and pollen available to various pollinator groups, and of fleshy fruits available to all seed-dispersing frugivores. In general, fire seems to have a neutral or even a positive effect on resource availability to mutualists. Nevertheless, there were differences in the availability of the resource utilized by each guild of mutualists.     

DNA methylation mediates the impact of exposure to prenatal maternal stress on BMI and central adiposity in children at age 13? years: Project Ice Storm

Prenatal maternal stress (PNMS) in animals and humans predicts obesity and metabolic dysfunction in the offspring. Epigenetic modification of gene function is considered one possible mechanism by which PNMS results in poor outcomes in offspring. Our goal was to determine the role of maternal objective exposure and subjective distress on child BMI and central adiposity at 13½ years of age, and to test the hypothesis that DNA methylation mediates the effect of PNMS on growth. Mothers were pregnant during the January 1998 Quebec ice storm. We assessed their objective exposure and subjective distress in June 1998. At age 13½ their children were weighed and measured (n = 66); a subsample provided blood samples for epigenetic studies (n = 31). Objective and subjective PNMS correlated with central adiposity (waist-to-height ratio); only objective PNMS predicted body mass index (BMI). Bootstrapping analyses showed that the methylation level of genes from established Type-1 and -2 diabetes mellitus pathways showed significant mediation of the effect of objective PNMS on both central adiposity and BMI. However, the negative mediating effects indicate that, although greater objective PNMS predicts greater BMI and adiposity, this effect is dampened by the effects of objective PNMS on DNA methylation, suggesting a protective role of the selected genes from Type-1 and -2 diabetes mellitus pathways. We provide data supporting that DNA methylation is a potential mechanism involved in the long-term adaptation and programming of the genome in response to early adverse environmental factors.     

Growth variations in OF1 mice following chronic exposure of parental and filial generations to a 15 μT, 50 Hz magnetic field

The growth of a first filial generation (F1) of OF1 mice was studied following chronic exposure of their mothers and themselves to a magnetic field of 15?μT (rms) and 50?Hz. The parental generation (F0) remained for 98 days in this field, after that time they were mated, went through pregnancy, birth, lactation, and the weaning of their offspring in this field. The latter remained exposed to this field until reaching adulthood (220 days). Control animals were treated in the same way but were exposed only to the Earth's magnetic field. The growth data for the offspring were analyzed using a generalization of Koop's equation. Using this model, four phases were identified: lactation growth acceleration, post-weaning growth acceleration, growth stabilization, and a stationary phase. Exposure to the artificial magnetic field was associated with a marked increase in maximum growth rate in the exposed animals during the post-weaning growth acceleration phase, and with a reduction in mass gain in the F1 mice (especially in males) during the third of these phases. In addition, the growth stabilization phase was more extended in exposed females and shorter in exposed males than in the control animals. Furthermore, statistically significant differences were seen between the mean body masses of exposed and control F1 males from 49-123 days. Exposure to the artificial magnetic field might have been associated with the stimulated growth rate seen over the noticeably shortened second and third growth phases (leaving these animals lighter by the stationary phase compared to controls) and a possible acceleration of aging. Both processes could be responsible for the stationary phase being reached at an earlier age, especially in males.     

The optimum and tolerance pH range is correlated to colonial morphology in isolates of the entomopathogenic fungus Beauveria bassiana – a potential biopesticide

Beauveria bassiana is an insect pathogenic fungus used as a biopesticide in crop pest management. It exists saprophytically in the soil. The pH of the soil and the insect cuticle and its haemocoel may influence fungal survival and infection potential. Therefore the tolerance and optimum pH ranges were studied in 29 isolates of B. bassiana. Germination and growth bioassays in liquid culture medium adjusted to pH values in the range 3–14 at unit intervals were studied. A pH of 3 was found to be toxic to all isolates – conidia germinated at this pH but growth was totally inhibited. All isolates tolerated a pH of 5–13. Some isolates showed tolerance to a pH of 4 and/or 14 as well. Sixteen isolates showed a wide range of pH optimum of 5–13 while others had a narrower optimal range. The relation of the pH tolerance and optimum range of an isolate to its phenotypic characters (colonial morphology and growth-rate) was studied. All isolates with a chalky type colonial morphology had an intermediate growth rate and showed a wide optimum range of pH 5–13 or 5–14. All isolates with dusty type colonial morphology were found to have a high growth rate and a wide pH tolerance range of 4–14. Both chalky and dusty colonial morphology are due to a growth pattern characterized by iterated conidiation with a very brief hyphal stage. The correlation observed between these traits based on external phenotype would facilitate prediction of the pH tolerance characters of an isolate of B. bassiana.     

Vhc1, a novel transporter belonging to the family of electroneutral cation–Cl− cotransporters,participates in the regulation of cation content and morphology of Saccharomyces cerevisiae vacuoles

Cation–Cl^? cotransporters (CCCs) are integral membrane proteins which catalyze the coordinated symport of Cl^? with Na⁺ and/or K⁺ ions in plant and mammalian cells. Here we describe the first Saccharomyces cerevisiae CCC protein, encoded by the YBR235w open reading frame. Subcellular localization studies showed that this yeast CCC is targeted to the vacuolar membrane. Deletion of the YBR235w gene in a salt-sensitive strain (lacking the plasma-membrane cation exporters) resulted in an increased sensitivity to high KCl, altered vacuolar morphology control and decreased survival upon hyperosmotic shock. In addition, deletion of the YBR235w gene in a mutant strain deficient in K⁺ uptake produced a significant growth advantage over the parental strain under K⁺-limiting conditions, and a hypersensitivity to the exogenous K⁺/H⁺ exchanger nigericin. These results strongly suggest that we have identified a novel yeast vacuolar ion transporter mediating a K⁺–Cl^? cotransport and playing a role in vacuolar osmoregulation. Considering its identified function, we propose to refer to the yeast YBR235w gene as VHC1 (vacuolar protein homologous to CCC family 1).     

Thermoregulatory responses to variations of photoperiod and ambient temperature in the male lesser mouse lemur: a primitive or an advanced adaptive character?

The lesser mouse lemur, a small Malagasy primate, is exposed to strong seasonal variations in ambient temperature and food availability in its natural habitat. To face these environmental constraints, this nocturnal primate exhibits biological seasonal rhythms that are photoperiodically driven. To determine the role of daylength on thermoregulatory responses to changes in ambient temperature, evaporative water loss (EWL), body temperature (T _b) and oxygen consumption, measured as resting metabolic rate (RMR), were measured in response to ambient temperatures ranging from 5 °C to 35 °C, in eight males exposed to either short (10L:14D) or long (14L:10D) daylengths in controlled captive conditions. In both photoperiods, EWL, T _b and RMR were significantly modified by ambient temperatures. Exposure to ambient temperatures below 25 °C was associated with a decrease in T _b and an increase in RMR, whereas EWL remained constant. Heat exposure caused an increase in T _b and heat loss through evaporative pathways. Thermoregulatory responses to changes in ambient temperature significantly differed according to daylength. Daily variations in T _b and EWL were characterized by high values during the night. During the diurnal rest, lower values were found and a phase of heterothermia occurred in the early morning followed by a spontaneous rewarming. The amplitude of T _b decrease with or without the occurrence of torpor (T _b < 33 °C) was dependent on both ambient temperature and photoperiod. This would support the hypothesis of advanced thermoregulatory processes in mouse lemurs in response to selective environmental pressure, the major external cue being photoperiodic variations. Accepted: 4 August 1998