Hormesis Phenomenon Research Articles

Антибиотик ципрофлоксацин в водных и почвенных средах: реакция микроводорослей

Pharmaceuticals and antibiotics in the environment are of increasing concern due to the impact on representatives of all links in the food chain of natural ecosystems. The effect of the widespread antibiotic ciprofloxacin (Cip) on the green protococcal microalgae Scenedesmus quadricauda and Chlorella vulgaris in water and aqueous soil extracts (artificial standard soil, technosoil, soddy-podzolic soil) was studied in model experiments. Fluorescent parameters were assessed by two different methods (Fluorat 02-5M and Water-PAM devices). The phenomenon of hormesis was observed at low antibiotic concentrations of 5 and 10 mg/L. A decrease in the photosynthetic activity of algae was recorded at an increase of Cip content from 20 to 50 mg/L. A comparison was made of the median (average effective) concentration of the EC50 antibiotic, which suppresses the fluorescent characteristics of microalgae by 50% on 3 days of exposure in different media. The decrease in the toxicity of the studied dose of Cip (300 mg/L) in a number of studied objects can be represented as follows: water > technosoil > artificial standard soil > soddy-podzolic soil. It reflects the percentage of inhibition of the test function relative to the control (samples without antibiotic) by 91.5, 80.0, 62.5, and 60.0% respectively. In the soil matrix, the inhibitory effect of the antibiotic is less pronounced (by 10–30%), probably due to the protective properties of humic substances that adsorb the antibiotic or its metabolites.

Morphological, Histological and Genetic Evaluation of Gamma Radiation-Induced Mutation and Its Potential Application in Rudbeckia hirta (L.)

Many cultivars of annual ornamental horticulture have great phenotypic qualities but are less tolerant to the effects of current climate change and urbanization. A good example of this in Hungarian ornamental breeding is the Rudbeckia hirta cultivar “Őszifény”. The objective of this study was to determine whether gamma mutation breeding (using 5 Gy, 10 Gy, 30 Gy doses) can be employed to enhance genetic variability and create mutants with novel trait values. Furthermore, it is important to ascertain whether the altered genetic traits are proportionate to the observed changes in phenotype. As an original and innovative aspect of the research, this will assist in establishing appropriate dose rates for the species. Changes induced by gamma radiation have been mapped using morphological, histological, and genetic methods. The radiation dose of 5 Gy resulted in plants with the most favorable characteristics, including significant increases in branching and flower number. Additionally, the phenomenon of hormesis was observed. Beyond these, the dose of 30 Gy also had a significant effect because it resulted in plants with many flowers and bushy habits, making them suitable for use as ornamental potted plants. The 10 Gy dose resulted in a heterogeneous stand but showed the greatest genetic variation. These results may contribute to future breeding work and may pave the way for further urban application of R. hirta in the light of urbanization.

Studying the Phenomenon of Hormesis and Its Effect on Insects

Studying the Phenomenon of Hormesis and Its Effect on Insects

Morpho-physiological, biochemical, and molecular responses of lettuce (Lactuca sativa L.) seedlings to chlortetracycline stress

Antibiotic contamination in soil is an emerging environmental problem due to its potential threat to the soil ecosystem. Among antibiotics, chlortetracycline (CTC) is widely used for livestock and accumulates in agricultural soil, leading to detrimental effects on various physiological and biochemical metabolic processes in crops. However, the adverse impacts of CTC on plants and their defensive mechanisms remain poorly understood. We aimed to investigate the physiological, biochemical, and molecular responses of lettuce to CTC toxicity and to understand better the regulatory mechanism influencing the growth and development of plants. In this study, lettuce seedlings were exposed to different CTC doses (0, 0.01, 0.1, 0.5, and 1 mg L–1) and grown for 4 weeks in a hydroponic system. The results showed that an initial CTC dose (0.01 mg L–1) induced a hormesis phenomenon in the seedling's growth accompanied by upregulation of anthocyanin production, and their biosynthesis and regulation-related genes (e.g., F3H, F3′H, DFR, UFGT, ANS, and MYB) were found upregulated. While increasing CTC doses displayed stimulated phenolic acid and flavonoid contents, it had negative impacts on plant growth and leaf fresh/dry biomass. A progressive increase in the contents of H2O2 and MDA in the plants was found as the CTC dose increased, while the relative water content (RWC) level decreased. The activities of antioxidant enzymes, like superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, displayed differential responses to CTC. In addition, CTC doses, especially at 0.5 and 1 mg L–1, tended to promote the production of abscisic acid and jasmonic acid, but salicylic acid remained unaltered. Overall, this study provides a new perspective insight into the toxic effects of CTC and the resilience mechanisms interlinked in lettuce plants' survival against antibiotic contamination.

Dosage impact of submerged plants extracts on Microcystis aeruginosa growth: From hormesis to inhibition

Allelopathy has been demonstrated to be an environmentally friendly way to control harmful algal blooms. Allelochemicals of submerged plants have attracted extensive research due to their bioavailability. The dose-response of submerged plant extracts on algae growth is worth further study to improve the efficiency of bioremediation. In this study, the ultrasonic-enzymatic assistance method was utilized to extract allelochemicals from Ceratophyllum, Myriophyllum spicatum, and Vallisneria. The effects of low-dosage and high-dosage extracts on the growth of Microcystis aeruginosa were compared based on cell biomass and morphology, photosynthetic parameters, reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels. The results showed that the three submerged plant extracts exhibited hormetic effects at low dosages and inhibitory effects at high dosages on algal growth. Within 48 h of cultivation, the enzymatic activities of Microcystis aeruginosa fluctuated, suggesting that the extracts of the three submerged plants induced different oxidative reactions. After 120 h of cultivation with high-dosage extracts, the physiological and biochemical reactions of Microcystis aeruginosa significantly decreased, indicating the effectiveness of the allelopathy of Ceratophyllum, Myriophyllum spicatum, and Vallisneria extracts in controlling algal blooms. The phenomenon of hormesis and inhibition effect confirmed a significant dose-response relationship between the allelochemicals of submerged plant extracts and Microcystis aeruginosa, which could be attributed to the composition and content of allelochemicals. These findings highlight the importance of the relative concentration of the biological algaecide and will benefit other researchers in determining the safe dosage of plant allelochemicals when used in water.

Herbicide-induced hormesis and its effect on crop development

The beneficial effect of growth stimulation caused by low doses of a toxic product such as an herbicide, is due to the phenomenon known as hormesis. Plants affected by this phenomenon show changes in their metabolism and, as a result, are able to increase nutrient absorption and biomass accumulation. Various herbicides have been developed as growth regulators, proving the hormesis hypothesis. The most notable example is the product 2,4-D, originally developed as auxin. This phenomenon can bring benefits for crops, such as increased yield. However, for the technique to be applied in practice, information is still needed to support its potential application in agriculture. The aim of this review was to define the state of the art and measure the effect of the hormesis phenomenon of herbicides in agriculture. To carry out a bibliographical review using the following databases: SciELO, Scopus, Web of Science, Redalyc, EBSCO, and DOAJ. The quality of the studies was assessed using eligibility, inclusion and exclusion criteria, employing the following indexing terms: dichlorophenoxyacetic acid, herbicide subdose, herbicide toxicity, and growth regulator. Based on a summary of the studies identified via electronic or manual searches relating to the phenomenon of hormesis, it was found that the literature on the subject remains ambiguous, with no consensus regarding the real effects of the phenomenon on crop performance. This article further argues that the magnitude of the hormetic effect on crops depends on several factors, such as the subdose, the age of the plant, and other conditions.

Eroticism as a hormetic stimulus in health and ageing

Eroticism in later life is, on the whole, a taboo subject, and the stigma attached to expressions of sexual intent by older people is widespread in most cultures. However, sexuality and eroticism have an important role to play in maintaining healthy ageing. Sexuality is an essential aspect of our biology and its effects have repercussions in systems and organs other than the sexual. In this paper I review the importance of developing a sexual-erotic element in later life, an element that is intimately coupled with the phenomenon of hormesis. In hormesis, there is biological benefit following exposure to a mild stimulus or challenge, whereas exposure to a higher dose of the same stimulus becomes detrimental. Innovative sexual stimulation can be seen as a hormetic opportunity to initiate beneficial effects on the entire ageing human organism. The intention is to show that, health benefits may be obtained not only through physical (exercise), nutritional, mental or pharmacological challenges, but also through sexual stimulation of the appropriate magnitude and quality. By enhancing erotic stimulation it may be possible to experience many other benefits spanning several domains such as the endocrine, immune, circulatory and neurological. In addition, within an increasingly information-rich world, sexuality may play a part in improving adaptation to various cognitive external stimuli originating from our technological ecosystem.

H2S-Generating Cytosolic L-Cysteine Desulfhydrase and Mitochondrial D-Cysteine Desulfhydrase from Sweet Pepper (Capsicum annuum L.) Are Regulated During Fruit Ripening and by Nitric Oxide.

Aims: Pepper fruit is a horticultural product worldwide consumed that has great nutritional and economic relevance. Besides the phenotypical changes that undergo pepper fruit during ripening, there are many associated modifications at transcriptomic, proteomic, biochemical, and metabolic levels. Nitric oxide (NO) and hydrogen sulfide (H2S) are recognized signal molecules that can exert regulatory functions in diverse plant processes. This study aims at analyzing the interrelationship between NO and H2S during fruit ripening. Results: Our data indicate that the H2S-generating cytosolic L-cysteine desulfhydrase (LCD) and the mitochondrial D-cysteine desulfhydrase (DCD) activities are downregulated during ripening but this effect was reverted after NO treatment of fruits. Innovation and Conclusion: Using as a model the non-climacteric pepper fruits at different ripening stages and under an NO-enriched atmosphere, the activity of the H2S-generating LCD and DCD was analyzed. LCD and DCD activities were downregulated during ripening, but this effect was reverted after NO treatment of fruits. The analysis of LCD activity by non-denaturing polyacrylamide gel electrophoresis (PAGE) allowed identifying three isozymes designated CaLCD I to CaLCD III, which were differentially modulated by NO and strictly dependent on pyridoxal 5'-phosphate (PLP). In vitro analyses of green fruit samples in the presence of different compounds including NO donors, peroxynitrite (ONOO-), and reducing agents such as reduced glutathione (GSH) and L-cysteine (L-Cys) triggered an almost 100% inhibition of CaLCD II and CaLCD III. This redox adaptation process of both enzymes could be cataloged as a hormesis phenomenon. The protein tyrosine (Tyr) nitration (an NO-promoted post-translational modification) of the recombinant LCD was corroborated by immunoblot and by mass spectrometry (MS) analyses. Among the 11 Tyr residues present in this enzyme, MS of the recombinant LCD enabled us to identify that Tyr82 and Tyr254 were nitrated by ONOO-, this occurring near the active center on the enzyme, where His237 and Lys260 together with the cofactor PLP are involved. These data support the relationship between NO and H2S during pepper fruit ripening, since LCD and DCD are regulated by NO during this physiological event, and this could also be extrapolated to other plant species.

Biostimulant and Elicitor Responses to Cricket Frass (Acheta domesticus) in Tomato (Solanum lycopersicum L.) under Protected Conditions.

Agriculture in the current century is seeking sustainable tools in order to generate plant production systems with minimal negative environmental impact. In recent years it has been shown that the use of insect frass is an option to be used for this purpose. The present work studied the effect of low doses (0.1, 0.5, and 1.0% w/w) of cricket frass (Acheta domesticus) in the substrate during the cultivation of tomatos under greenhouse conditions. Plant performance and antioxidant enzymatic activities were measured in the study as explicative variables related to plant stress responses in order to determine possible biostimulant or elicitor effects of cricket frass treatments during tomato cultivation under greenhouse conditions. The main findings of this study indicated that tomato plants responded in a dose dependent manner to cricket frass treatments, recalling the hormesis phenomenon. On the one hand, a 0.1% (w/w) cricket frass treatment showed typical biostimulant features, while on the other hand, 0.5 and 1.0% treatments displayed elicitor effects in tomato plants under evaluated conditions in the present study. These results support the possibility that low doses of cricket frass might be used in tomato cultivation (and perhaps in other crops) for biostimulant/elicitor input into sustainable production systems.

Combined strategy for 17-α-ethynilestradiol removal, CO2 fixation, and carotenoid accumulation using Thermosynechococcus sp. CL-1 cultivation

An isolated cyanobacterium, Thermosynechococcus sp. CL-1 (TCL-1), is a potential CO2 fixation, estrogen removal, and pigments production agent even under extreme conditions. In this study, TCL-1 was cultivated under various 17-α-ethinylestradiol/EE2 contents and growth conditions (light intensities and dissolved inorganic nitrogen/DIN). Under low EE2 concentration (1 mg/L), TCL-1 presented hormesis phenomenon with promotion of biomass productivity (68.2 ± 0.6 mg/L/h) and β-carotene productivity (0.47 ± 0.12 mg/L/h) compared to control cultivation without EE2. Strong endurance of TCL-1 was indicated by insignificant biomass growth reduction, even under 10 mg/L EE2. Moreover, compared to the variety of DIN levels, light intensity presented a greater influence on growth, CO2 fixation, and carotenoid accumulation of TCL-1. Total EE2 removal by TCL-1 reached the range of 66.4–82.3 % and the process was initiated by adsorption on cells’ surfaces prior to accumulation.

МЕХАНИЗМЫ ПРОТИВООПУХОЛЕВОГО ДЕЙСТВИЯ МАЛЫХ ДОЗ РАДИАЦИИ, СВЯЗАННЫЕ С АКТИВАЦИЕЙ ЗАЩИТНЫХ СИСТЕМ КЛЕТКИ

Background: The effects of ionizing radiation (IR) involve a highly orchestrated series of events in cells, including DNA damage and repair, cell death, and changes in the level of proliferation associated with the stage of the cell cycle. A large number of existing studies in literature have examined the activity of genes and their regulators in mammalian cells in response to high doses of ionizing radiation. Although there are many studies, the research in effect of low doses of ionizing radiation remains limited. Though much progress has been made in understanding the basic principles of effects of low doses radiation on individual components of biological systems, less is known about how low doses affect target molecules and regulate the cellular networks (e.g., activation of the immune system, genes and their regulators in the phenomenon of hormesis, the formation of an adaptive response). These observations determined the purpose of the work: to investigate the activity of genes and non-coding RNAs (long non-coding RNAs and microRNAs) in various organs of mice with transplanted Lewis carcinoma after low doses radiation. Material and methods: 24 female mice C57Bl/6 were transplanted subcutaneously with Lewis carcinoma cells (105 cells in 0.2 ml of Hanks’ solution). Total 4-fold X-ray irradiation with an interval of 4 days at a dose of 0.075 Gy (0.85 Gy/min) was performed on the RUST M1 from 6 days after transplantation; the tumor size was measured daily. The mice were divided into the following groups: biocontrol, biocontrol+irradiation, tumor and tumor+irradiation. On the 19th day from the beginning of the experiment, the mice were euthanized. The expression profiles of mRNA genes, long non-coding RNAs and microRNAs controlling the response to radiation were determined in the bone marrow, thymus, spleen and tumor of mice. Results: Fractionated low doses irradiation of mice with transplanted Lewis carcinoma caused a growth decrease of implanted tumour cells compared to the similar group without irradiation. At the same time, there was an activation of oncosuppressors, and a decrease in the activity of oncogenes in the thymus and spleen of mice with tumor and irradiation. In the tumor group, without irradiation, the number of activated oncogenes prevailed over the number of inactivated ones. Conclusion: Thus, the low doses radiation exposure led to the activation of antitumor immunity in mice, which emerged in slowing tumor growth in animals and was represented in the induction of oncosuppressors and inhibition of oncogenes expression.

Assessing OBT formation and enrichment: ROS signaling is involved in the radiation hormesis induced by tritium exposure in algae.

Tritium is the main component of radioactive wastewater from nuclear power plants and can be migrated into organisms to form organically bound tritium (OBT), which may pose a potential risk to aquatic ecosystem. Hence, it is essential to monitor OBT conversion in the presence of tritium exposure. In this study, the effects of pretreatment methods such as digestion on the recovery of tritium were discussed. It was found that microwave digestion pretreatment could improve the recovery of tritium by up to 90 % and allow OBT measurement with a small sample size equivalent to about 60mg (dry weight). In addition, the efficiency of OBT transformation was different among biological samples, and the radiation hormesis phenomenon was induced by tritium exposure (3.7× 106 Bq/L) in microalgae Chlorella vulgaris（C. vulgaris）. The tritium exposure may induce radiation hormesis through the reactive oxygen species (ROS) signaling pathway, thus improving the photosynthetic capacity and metabolism level of C. vulgaris. Furthermore, enhancement of photorespiration metabolism and the antioxidation system may be important means for C. vulgaris to balance damage by tritium radiation. This study provides insights for further investigating OBT behavior, and will contribute to understanding the equilibrium damage mechanism of algae exposed to tritium.

The Level of Individual Biochemical Constants of the Brain of in the Krushinsky-Molodkina Inbred Rat Strain against the Background of Radon Inhalation During Epilepsy

Introduction: The elucidation of the mechanism of action of radon on antioxidant processes needs further research, however, based on the results of the experiment, it can be concluded that studies on experimental animals have shown that, while inhaling Tskhaltubo water, the phenomenon of hormesis develops.
 Methods: we placed 10 experimental animals (KM rats) in Radon contained mineral water spa`s sauna. Inhalation of radon-water was administered through the nose, for 10 minutes, once a day, in conditions of high humidity (about 90%) for 10 days.
 Results: Hormesis regulates oxidative processes in the brain due to the activation of antioxidants expressed in a decrease in existing epileptic seizures and is expressed in the activation of Na / K-ATPase and specific glutaminergic neurons of the "attack center" of the hypothalamus but also with the activation of the entire adaptive-compensatory system.
 Conclusion: Inhalation of radon contained water can be considered as a method of treatment with an anticonvulsant effect confirmed by experimental studies.

Sub-lethal doses of imidacloprid alter food selection in the invasive garden ant Lasius neglectus

Despite several restrictions to their use, neonicotinoid insecticides are still widely employed worldwide. Residual sub-lethal amounts of these chemicals can have detrimental effects on the behavior of non-target insects. Toxic effects on economically important species such as bees have been widely documented, but less is known about their toxic action on other social insects, such as ants. In this study, we assessed the effect of different sub-lethal doses of the neonicotinoid imidacloprid on the ability of colonies of the invasive ant Lasius neglectus to select the most profitable resource. We used Y-shaped mazes having an imidacloprid-polluted or an unpolluted sucrose solution on the two branches. Two sucrose (0.1 M, 0.5 M) and two imidacloprid (1 μg/ml, 10 μg/ml) concentrations were used. In parallel, we evaluated the marking activity of foragers who fed on the same solutions. We found that the 0.1 M sugar solution polluted with 1 μg/ml imidacloprid was significantly more frequently selected in binary choices experiments than the unpolluted resource. Moreover, the ingestion of the same combination of sugar and imidacloprid significantly increased the marking rate of foragers. The higher concentration of the pollutant had lower effects, probably because of the hormesis phenomenon. Results suggest that the lower sub-lethal dose of imidacloprid can lead ants to select again the polluted resource. This “active” selection of the pollutant may magnify the negative effects on the colonies. Due to their ecological role, any impairment of ant survival or behavior may have detrimental cascade effects on the whole ecosystem.

Effects of Salicylic Acid on Heavy Metal Resistance in Eukaryotic Algae and Its Mechanisms.

Heavy metal pollution and water eutrophication are still the main issues to be solved in the environmental field. To find a biological control method for Cd2+-contaminated water or combined eutrophication and Cd2+ pollution water, the effects of salicylic acid on heavy metal Cd2+ resistance in eukaryotic algae Scenedesmus obliquus and Chlorella pyrenoidosa and its mechanisms were studied. The results showed that the inhibition rates of 3.0 mg/L Cd2+ stress group at 96 h were 67.0% on S. obliquus and 61.4% on C. pyrenoidosa and their uptake of Cd2+ was 0.31 mg/g and 0.35 mg/g, respectively. When adding the different concentrations of salicylic acid while stressed by 3.0 mg/L Cd2+, the hormesis phenomenon of low dose stimulation and high dose inhibition could be seen, and the inhibition rates of 30 mg/L~90 mg/L salicylic acid addition groups were significantly lower than those of the Cd2+ stress group alone, which were statistically significant (p < 0.05) and the absorption of Cd2+ was dramatically improved. Except for the 120 mg/L salicylic acid addition group, the chlorophyll fluorescence parameters (Fv/Fm and YII), glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) activities of all the other concentration groups were significantly higher than those of the Cd2+ stress group alone, p < 0.05.; the algal cell morphology in low concentration groups (30 mg/L and 60 mg/L) was also less damaged than those in the Cd2+ stress group alone. These indicate that the low concentrations of salicylic acid can counteract or protect the algal cells from Cd2+ attack, the mechanisms, on the one hand, might be related to the chelation of heavy metals by salicylic acid, resulting in the decrease of the toxicity of Cd2+; on the other hand, low concentrations of salicylic acid can stimulate the growth of these two algae, improve their photosynthetic efficiency and antioxidant capacity, as well as maintain the relative integrity of algal morphological structure.

Thiamethoxam in soybean seed treatment: Plant bioactivation and hormesis, besides whitefly control?

Amid concerns on the myriad of existing chemical stressors in agroecosystems, pesticides and particularly neonicotinoid insecticides are in the forefront. Despite that, these neurotoxic compounds remain the dominant group of insecticides in worldwide use with the added versatility of use in seed coatings. Such use sparks environmental concerns counterbalanced by their reported insecticidal efficacy and potential plant bioactivation. Nonetheless, this alleged double benefit and interconnection expected with neonicotinoids has been little explored particularly when the whole plant phenology is considered. Regardless of the expected efficacy against targeted insect pest species, like whiteflies, neonicotinoids may spark dual effect on plants – negative at higher concentrations, positive at low concentrations, which is consistent with the hormesis phenomenon that may be expressed as a plant bioactivation. This effect may also cascade to the targeted insect species, what deserves attention. Therefore, soybean seeds treated with increasing concentrations of the neonicotinoid thiamethoxam were followed throughout their development in greenhouse, recording the plant response and yield, besides their effect in whiteflies (Bemisia tabaci MEAM1). Thiamethoxam application was correlated to leaf contents of thiamethoxam and its metabolite clothianidin. Plant hormesis was found for leaf area and root growth, but not for other plant morphological or physiological parameters, nor plant yield. The insecticide concentration-dependency compromised whitefly population growth without evidence of cascading any plant-mediated hormesis to the insects. Thus, although plant hormesis was recognized with thiamethoxam in treated soybean seeds in relevant parameters, no evidence of plant bioactivation was observed to justify its use with such a secondary objective, nor did this hormesis impair whitefly control.

Стимулювання системи протеїназа-інгібітор протеїназ у результаті імерсійної гіпотермії

The effect of immersion hypothermia (IН) on proteolysis activity in adult male rats, which was performed at 0 °C for 5 min in the “forced swimming” test, studied; the body temperature decreased to 27.5 ± 0.5°C. In blood serum and non-nuclear fractions of homogenates of cerebral cortex, hypothalamus, cerebellum, brainstem, lungs, heart, liver and kidneys tissues were determined the total proteinase activity (TPA), non-trypsin-like proteinases (NTPs), such as chymase, prostate-specific antigen, partially tonin, kallikrein rK9, as well as trypsin-inhibitory activity of α-1-proteinase inhibitor (α-1-PI), α-2-macroglobulin (α-2-MG) by highly sensitive (10-9–10-10 g) enzymatic methods. It is noted that IH led to the TPA increase in all studied tissues (4-84 times), which corresponds to the psycho-emotional effects and the phenomenon of hormesis. After 24 h, TPA decreased, remaining above the control level, and in the kidneys increased further (90 times). NTLP activity as a result of IH increased in blood serum and cerebellum, decreased in the hypothalamus, and after 24 h increased further in serum (7 times), cerebellum, and heart. The activity of α-1-PI also increased in the brainstem, lungs, heart and kidneys, and decreased after 24 h in serum below the control level, and in the brainstem remained high, protecting against proteolytic attack. The activity of α-2-MG increased in the hypothalamus, heart, and cerebral cortex, maximum in the brainstem (2-5 times), and after 24 h - more significantly (24 times), but there were no changes in the cerebellum, where its initial level is the biggest. Thus, the development of IG as a result of swimming in cold water for 5 min at 0oC has a stimulating effect on the body and leads to a significant activation of the reactions of limited proteolysis.

Effects of trace elements contaminations on the larval development of Paracentrotus lividus using an innovative experimental approach.

Several experiments were performed using larvae of Paracentrotus lividus (Lamarck, 1816) in order to determine the consequences of different chronic contamination with mixtures of (i) fifteen trace elements from concentrations measured in the world ocean seawater, and (ii) seven trace elements from contamination resulting from mining. To predict the impact of increased marine pollution, higher concentrations were also used. These bioassays were conducted using spawners collected from Calvi (reference site, Corsica), and Albo (mining area, Corsica). The effects of trace elements have been studied on the entire larval development. The results show wider arms and delayed development as the number and concentration of trace elements increases. Therefore, the synergy between the different trace elements is of paramount importance with regard to the impact on organisms. Probably due to a hormesis phenomenon, larvae contaminated with seven trace elements at average concentrations developed more quickly. This work also highlighted the importance of the origin of spawners in ecotoxicological studies. To our knowledge, this is the first study to investigate the effects of such a broad combination of trace elements for chronic contamination on the entire larval stage of Paracentrotus lividus.

Quinolone antibiotics enhance denitrifying anaerobic methane oxidation in Wetland sediments: Counterintuitive results

Denitrifying anaerobic methane oxidation (DAMO) plays an important role in the element cycle of wetlands. In recent years, the content of antibiotics in wetlands has gradually increased due to human activities. However, the impact of antibiotics on the ecological function of DAMO remains unclear. Here we studied the influence of three high-content quinolone antibiotics (QNs) on DAMO in the sediments of the Baiyangdian Wetland. The results show that QNs can significantly promote the potential DAMO rates. Moreover, the enhancement of potential DAMO rates is positively correlated with the dosage of QNs. This promotion effect of QNs on nitrate-DAMO can be attributed to the hormesis phenomenon or their inhibition of substrate competitors. As antibacterial agents, QNs inhibit nitrite-DAMO conducted by bacteria, but greatly promote nitrate-DAMO conducted by archaea. These results suggest that the short-term effect of QNs on DAMO in wetlands is promotion rather than inhibition.

Mathematical modeling and dynamical analysis of anti-tumor drug dose-response.

Cancer is a serious threat to human health and life. Using anti-tumor drugs is one of the important ways for treating cancer. A large number of experiments have shown that the hormesis appeared in the dose-response relationship of various anti-tumor drugs. Modeling this phenomenon will contribute to finding the appropriate dose. However, few studies have used dynamical models to quantitatively explore the hormesis phenomenon in anti-tumor drug dose-response. In this study, we present a mathematical model and dynamical analysis to quantify hormesis of anti-tumor drugs and reveal the critical threshold of antibody dose. Firstly, a dynamical model is established to describe the interactions among tumor cells, natural killer cells and M2-polarized macrophages. Model parameters are fitted through the published experimental data. Secondly, the positivity of solution and bounded invariant set are given. The stability of equilibrium points is proved. Thirdly, through bifurcation analysis and numerical simulations, the hormesis phenomenon of low dose antibody promoting tumor growth and high dose antibody inhibiting tumor growth is revealed. Furthermore, we fit out the quantitative relationship of the dose-response of antibodies. Finally, the critical threshold point of antibody dose changing from promoting tumor growth to inhibiting tumor growth is obtained. These results can provide suggestions for the selection of appropriate drug dosage in the clinical treatment of cancer.