Increase In Lead Concentration Research Articles

Comprehensive Assessment of Lead Bioaccumulation in Helix aspersa (Müller, 1774), Snails: A Study of Histopathological and Biochemical Impacts

Background: The snail Helixa spersa is considered a relevant bioindicator of soil pollution by metallic elements due to its resistance and accumulation capabilities. Methods: This study aims to determine the dose-response relationship between different concentrations of lead and its toxic effects on juvenile H. aspersa through a semi-static ecotoxicity test under controlled conditions. In addition, continuous monitoring of carbohydrates, lipids and proteins of the snails affected by this metal was evaluated along with a histopathological study of the hepatopancreas. Result: The two-month lead exposure in H. aspersa resulted in significant alterations in biochemical and histological parameters. Lead concentrations in the hepatopancreas and foot exhibited a dose-dependent increase, with higher levels observed in the former. Elevated lead concentrations (1000 ìg/g and 1500 ìg/g of soil) led to substantial protein increase in both organs, while even lower doses displayed considerable protein elevation in the hepatopancreas. Carbohydrate levels were significantly lower in all contaminated groups compared to controls. Increasing lead concentrations caused a reduction in lipid levels. Histological analysis revealed distinct alterations, including excretory cell hypertrophy, tubule clustering and inflammatory changes in the hepatopancreas of treated snails. Severe histological damage, including inflammatory infiltrates, cellular debris and necrosis, were observed at higher lead concentrations (1000 and 1500 ìg/g). These findings emphasize the impact of lead exposure on biochemical profiles and organ histology in H. aspersa, highlighting the potential ecological implications of heavy metal contamination.

Association between exposure to heavy metals in atmospheric particulate matter and sleep quality: A nationwide data linkage study

BackgroundRecent studies have demonstrated that long-term exposure to particulate matter (PM) is associated with poor sleep quality. However, no studies have linked PM constituents, particularly heavy metals, to sleep quality. ObjectiveThis study investigated the association between exposure to heavy metals in PM and sleep quality. MethodsWe obtained nationwide data from the Korean Community Health Survey conducted in 2018 among adults aged 19–80 years. Sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). Poor sleep quality was defined as PSQI ≥5. One-year and three-month average concentrations of heavy metals (lead, manganese, cadmium, and aluminum) in PM with diameter ≤10 μm were obtained from nationwide air quality monitoring data and linked to the survey data based on individual district-level residential addresses. Logistic regression analyses were performed after adjusting for age, gender, education level, marital status, smoking status, alcohol consumption, history of hypertension, and history of diabetes mellitus. ResultsOf 32,050 participants, 17,082 (53.3%) reported poor sleep quality. Increases in log-transformed one-year average lead (odds ratio, 1.14; 95% confidence interval, 1.08−1.20), manganese (1.31; 1.25−1.37), cadmium (1.03; 1.00−1.05), and aluminum concentrations (1.17; 1.10−1.25) were associated with poor sleep quality. Increases in log-transformed three-month average manganese (odds ratio, 1.13; 95% confidence interval, 1.09−1.17) and aluminum concentrations (1.28; 1.21−1.35) were associated with poor sleep quality. ConclusionWe showed for the first time that exposure to airborne lead, manganese, cadmium, and aluminum were associated with poor sleep quality. This study may be limited by self-reported sleep quality and district-level exposure data.

Interaction between Haematococcus pluvialis microalgae and lead nitrate: lead adsorption from water

Our study aims to investigate the response of the unicellular alga, Haematococcus pluvialis, to the toxicity of lead and propose a low-cost, highly efficient biological adsorbent for the purification of wastewater and lead-contaminated water. The first part examines the effects of lead toxicity on certain physiological indicators of this alga. In the second part, the potential of this alga in lead removal and its adsorption capacity was assessed. The alga was cultivated in a BG11 medium and treated with lead nitrate concentrations of 10, 50, and 200 mg/L during its exponential growth. The results showed that with an increase in lead concentration up to 200 mg/L, the growth rate, chlorophyll a, chlorophyll b, carotenoid and total protein content decreased, while malondialdehyde (MDA) content increased. The astaxanthin content slightly increased at the 10 mg/L but decreased at the 200 mg/L treatment. Maximum lead adsorption was observed at 98.69% under optimal conditions, including a pH of 6, an adsorbent dose of 1 g/L, a lead concentration of 25 mg/L, a temperature of 25 °C, and an exposure time of 120 min. The results of this study demonstrate that Haematococcus pluvialis has the potential for effective lead removal from aquatic environments.

Characterization of stress indicators in Tilia cordata Mill. as early and long-term stress markers for water availability and trace element contamination in urban environments

In the context of current climate change, municipalities tend to plant more trees in order to benefit from services they provide in urban areas, such as reducing heat islands. However, in cities, trees are subject to severe abiotic constraints, the main ones being soil contamination and the lack of water due to soil compaction and droughts. This can negatively impact the ecological services provided by trees. Our study aims to help managers in monitoring the phytosanitary status of trees in order to be able to react promptly. In a controlled condition experiment, different plant compounds were analyzed (proline, malondialdehyde-MDA, photosynthetic pigments) in the leaves of young linden trees conventionally grown for planting by the City of Paris, France. They were grown on a trace element (TE) contamination soil gradient, and under different water regimes (well-hydrated/no water stress (Ct), dehydration (Dh), rehydration (Rh)) to see if tested compounds could be early stress markers in trees. Chlorophylls (Chl) could be considered as water and TE-mediated stress markers. Indeed Chl a and b concentrations significantly decreased with dehydration (e.g. respectively −34 % and −24 %) and increasing lead concentration in leaves (respectively, correlation coefficients were −1.08; −0.64 (p < 0.001)). On the contrary, Chl concentrations increased with increasing copper concentration in optimal physiological ranges (correlation coefficients for Chla and Chb were respectively 1.3 and 1.08 (p < 0.05)). Proline and malondialdehyde seemed to be good complementary markers of water stress in the Tilia genus. Indeed, proline concentration increased during the dehydration period (early water stress marker) (mean concentration for Ct, Dh and Rh trees were respectively 3.6, 29.6 and 51.3 µmol.g−1 DW), while MDA increased during the rehydration process (marker for stress accumulation over time) (mean concentration for Ct, Dh, and Rh were respectively 461.8, 313.9 and 493.5 nmol.g−1 DW). In order to reinforce the diagnoses of urban tree managers, these stress indicators should be tested in situ.

Effect of Lead Toxicity on Wild Cannabis Species of Punjab Region

Human activities are causing environmental pollution in many ways by contaminating air, water and soil by adding different types of pollutants. Among various pollutants, heavy metals are an emerging threat in today’s world which are degrading our environment in a number of ways. Lead is the most widespread and evenly distributed poisonous element. Due to urbanization and growing human activities, lead emissions in different forms have increased, resulting in the contamination of soil and water. The lead transfers from environment to different forms of life, disrupting biological processes and causing various health issues. In this article, pot culture experiments were carried out to analyse the stress of Lead (Pb) and the capability of Cannabis sp. to tolerate the stress by studying the impact of different concentrations (0 mg/kg, 50 mg/kg, 100 mg/kg and 150 mg/kg of soil) on various biochemical aspects of the plant (Photosynthetic pigments, protein, antioxidant enzyme activity). Lead was given in the form of lead acetate. The results showed that the photosynthetic pigments-chlorophyll and carotenoid decreased with increasing lead concentration. Same effect was shown by the protein content in the leaves. On the other hand, Superoxide Dismutase (SOD), which is an antioxidant enzyme, increased with increasing concentration of lead.

Detection of Lead (Pb) and Cadmium (Cd) Concentrations and Hazards in Some Baby Food Samples

This study was conducted to detect the concentration of lead and cadmium in baby foods, (18) samples were examined, which are the most available from various local markets in the city of Baghdad (at a rate of (9) samples of baby food consisting of cereals and (9) samples of baby foods consisting of vegetables). All samples were examined using an atomic flame absorptiometry (AAS-7000), all results showed the presence of lead and cadmium and the highest concentration value of lead in baby foods consisting of cereals (1.0986) and cadmium in baby foods consisting of vegetables (0.0015) ppm. Lead exceeded 100% limitations and cadmium did not exceed that. The results reported on the risks of contamination, as the mean daily intake (g/kg/d) for lead (1.3538) and cadmium amounted to (0.010), and the target hazard quotient index was high for the index (THQ&gt;10) for lead in most of the samples examined and reached (THQ&lt;10) in some samples examined, while cadmium all samples reached an index of (THQ&lt;10). The study showed an increase in lead concentrations and perceptible risks and did not report an increase in cadmium concentrations outside the determinants, but it warns of imperceptible risks to the consumer. The study showed statistically significant differences between the levels of lead and cadmium and between the studied species and did not show statistically significant differences between the origins at the level of significance (0.05). It has been shown that these products pose a risk to children when consumed, so these products must be banned and ways must be found to reduce or prevent these pollutants with these products or find appropriate alternatives.&#x0D;

Lead isotope ratio analysis of lead ingots and bronze wares unearthed from Yinxu

AbstractThis study gives the element compositions and Pb isotope ratios of three lead ingots and three bronze artefacts unearthed from Yinxu, Anyang, Henan province, and two lead vessels from Zhengxiaozhuang tomb, Anhui province, China. The results of composition analysis show that three lead ingots in Yinxu may be the primary product of lead smelting. The lead wares unearthed in Zhengxiaozhuang tomb could be a kind of Mingqi‐funerary replicas. The results of Pb isotope analysis indicate that the culture exchanges between the Central Plains and the Jianghuai area in the late Shang dynasty. The decrease of bronzes with the highly radiogenic lead is consistent with the increase of Pb content in Yinxu bronzes simultaneously, which could be related to the change of lead source.

Chronic lead exposure prolongs the immature stages of brown-legged grain mite, Aleuroglyphus ovatus, in a long-term population study

An important aspect of environmental pollution, lead contamination is a widespread problem in several ecosystems. The present study aimed to evaluate the potential effects of low concentration lead stress on the development and reproduction of Aleuroglyphus ovatus. They were fed with artificial diet containing four different concentrations of lead (12.5, 25, 50, and 100 mg/kg). The results showed that there were both accelerating effect of lead (at low concentrations), as well as retarding effects (at high concentrations) on the development of the mite, and lead stress significantly prolonged the immature stages of A. ovatus and this inhibitory effect was greater with greater lead concentrations. The immature stages in the L group were shorter than those in the S group. In the S and L groups, the oviposition periods were significantly longer in the treatments with lower lead concentrations than in the control, while they were significantly shorter in those treatments of higher lead concentrations. Age-specific survival rate (lx) started to decline earlier in the S group, whereas there were no differences between the L group and CK. Age-specific fecundity rate (mx) peaked earlier in the S group than in CK, while mx peaked later in L1 and L2 than in CK. The rm value and net reproduction rate (R0) of treated A. ovatus decreased with increasing lead concentrations. Lower lead concentrations could promote population expansion while higher concentrations could inhibit population size. These results confirmed the developmental effect of lead stress on A. ovatus, highlighting that heavy metal contamination has negative effects on organisms in their natural environment.

Effects of Combined Pollution of Microplastics and Lead on Maize Seed Germination and Growth

Microplastics are a new contaminant that are causing worldwide concern. However, an understanding of their impact on agricultural seed germination remains inadequate. To investigate the effects of combined microplastic and heavy metal contamination on crop seed germination and growth, the effects of exposure to different single and combined concentrations of lead (Pb) and three microplastics[polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC)] on maize seed germination and growth were investigated using maize seeds. The results showed that:the inhibition of maize seed germination by Pb single exposure generally increased with Pb concentration. Compared with that in CK, 500, 1000, and 1500 mg·L-1 PE exposure significantly inhibited maize seed germination, but 100 and 300 mg·L-1 exposure had no significant effect (except at d 5). All PP concentration exposures significantly inhibited maize seed germination, with higher concentrations resulting in stronger inhibition. Compared to that under PP and PE exposure, PVC single exposure inhibited maize germination less, and 500, 1000, and 1500 mg·L-1 exposures produced a facilitative effect at the later stages of germination. The germination index, germination potential, and vigor index of maize seeds decreased with the increase in the single exposure concentration of lead and three types of microplastics, significantly decreased compared with that of CK under the combined exposure of Pb and PE, and did not change significantly under the combined exposure of PP and Pb or PVC and Pb. Among the three types of microplastics, PVC had the least effect on corn seed vigor. Both single exposures of 10 mg·L-1Pb and 100 mg·L-1 of the three microplastics promoted maize stalk and root growth, whereas other concentrations showed mostly inhibitory effects. When the PE concentration was 500 mg·L-1, the 10 and 20 mg·L-1Pb exposures both promoted maize seed stalk and root growth; however, the combined PP and Pb exposures did not produce significant inhibition, whereas 500 mg·L-1PVC and 10 mg·L-1Pb showed the strongest inhibition of maize stalk and root growth under combined PVC and Pb exposures. The effects of combined exposure to microplastics and Pb on the germination and growth of maize seeds were essentially antagonistic, thus slowing down the toxic effects of their respective single exposures on maize seeds.

Regulation of three subtypes of SOD gene in Aleuroglyphus ovatus (Acari:Acaridae) under lead stress.

Superoxide dismutase (SOD) is an important enzyme that acts as the first line of protection in the mite antioxidant defense system, involved in eliminating reactive oxygen species (ROS) under harsh environmental conditions. Nevertheless, the SOD gene family was yet to be reported in stored grain pest mite (Aleuroglyphus ovatus). In this study, A. ovatus was used to evaluate the response of SOD gene during lead stress. A. ovatus were separately exposed to different concentration lead (12.5, 25, 50, and 100 mg/kg), which induce the dynamic trend of SOD enzyme activity initially increased and then reduced with an increase in lead concentration, whereas they were still substantially higher than the control group. Moreover, after lead stress, it was found that all of the three SOD genes showed enhanced relative messenger RNA expression at high concentrations and decreased relative expression at low concentrations, which indicated that lead stress induces the expression of AoSODs. The present work implies that AoSODs play an important role in resisting oxidative damage caused by lead stress.

Ameliorative potential of the quercetin on lead-induced testicular damage: morphohistometric and biochemical analysis

BackgroundQuercetin, a naturally occurring flavonoid known for its potent antioxidant properties, has been investigated for its potential in counteracting the harmful effects of lead (Pb) toxicity, which induces apoptosis and oxidative damage in various human tissues. This study aims to assess the reparative effects of quercetin on lead-induced testicular damage.MethodsFour groups, each comprising ten adult male albino rats, were randomly assigned as follows: Quercetin group, Pb group, Pb + Quercetin group, and control group. All treatments were administered orally via gavage daily for a duration of 30 days. Evaluation of sex hormone levels (serum testosterone, FSH, and LH), cytokines and inflammatory mediators (IL-1β, TNF-α, MCP-1), lead concentration, oxidative and antioxidant stress markers (superoxide anion [O2−], MDA, SOD, CAT, GSH), and sperm characteristics were carried out.ResultsThe results demonstrated a significant decline in sex hormones and antioxidants, accompanied by an increase in lead concentrations, cytokines, inflammatory mediators, and oxidative stress indicators (O2−, MDA), while SOD, CAT, and GSH levels were reduced. The Pb-intoxicated group exhibited a substantial increase in dead and abnormal sperm, along with significant reductions in sperm concentration and motility. Morphometrically, a marked decrease was observed in spermatogonia, primary spermatocytes, spermatids, and sertoli cells per seminiferous tubule, as well as epithelial height. Furthermore, coadministration of quercetin exhibited notable benefits. It significantly elevated testosterone levels (P < 0.001), testicular SOD, CAT, and GSH activities, while decreasing MDA levels (P < 0.001). Quercetin also mitigated the deleterious effects of lead toxicity on sperm parameters and restored morphometric variations, including epithelial height.ConclusionsQuercetin supplementation alongside lead exposure showed a potential for ameliorating degenerative changes caused by lead toxicity in the testicles. This cotreatment effectively reduced oxidative stress, cytokine levels, inflammatory mediators, and restored biochemical alterations, thereby improving morphometric parameters.

Achromotrichia due to hypocupremia in a dog

A five-year-old, intact, female, brown Labrador retriever was presented for loss of hair color (achromotrichia). Clinical and blood examinations revealed no significant abnormalities, except for a considerably reduced serum copper measurement. This has been described in dogs and cattle as achromotrichiosis due to hypocupremia. Interference of intestinal copper absorption due to an increased lead concentration in the drinking water was assumed to be the cause. The dog’s haircoat became brown again after serving tap water as drinking water and adding a copper supplement.

The absorption and accumulation of lead in dracaena sanderiana plant

Heavy metals are the most dangerous substances in the environment, have caused deleterious effect not only to the environment but also to the public’s health. Different studies have demonstrated that plants have a high removal capacity for lead ions from pollution sources. However, these plant species were rather limited. Thus, the project aimed to find out plant species that represent its lead removal ability to reduce environmental pollution. The experiment was carried out factorially as a randomized complete design in hydroponic systems with four treatments (0, 100, 200, and 300mg/l of Pb) and three replications. The results indicated that the growth of the Dracaena sanderiana plant is well in Pb concentration of 100mg/l, with less growth while the increasing lead concentration of 200 mg/l and 300 mg/l. The amount of lead in the water of three treatments 100mg/l, 200mg/l, and 300mg/l after 30 days of the experiment decreased by 91.5%, 86.8%, and 86.4%, respectively. It was found that Dracaena sanderiana exhibited high lead treatment efficiency in the water. Moreover, results showed that the accumulation of lead in the roots of Dracaena sanderiana is quite large with treatments of 100mg/l, 200mg/l, and 300mg/l lead concentrations were 5073.8mg/kg, 5134.0mg/kg, 7054.0mg/kg, respectively. In contrast, the ability to lead accumulation in plant leaves and stems is lower.

Effect of Pb on microstructure and mechanical properties of Tin Babbitt alloy

This paper mainly studies the microstructure and properties of babbitt alloys, and analyzed the influence of lead on the microstructure and properties of the alloys by adding alloying element Pb, The results show as follows:with the increase of Pb content, the hardness of ZSnSb11Cu6 alloy first increases and then decreases. The maximum at 0.75% is 26.96HB. The tensile strength and elongation showed a trend of rising, then falling and then rising, and the mechanical properties were relatively high at 0.35%.The addition of Pb changes the morphology of Cu6Sn5 phase. With the increase of lead content, the β phase decreases and then grows, and the needle-like η phase dendrite grows.

A cross-sectional study of the association between heavy metals and pan-cancers associated with sex hormones in NHANES 1999–2018

Given the complexity of tumorigenesis, numerous studies have also shown that excessive exposure to heavy metals increases the risk of cancers and disrupts the secretion of sex hormones. However, the specific effects of heavy metals on cancers remain to be proven. To confirm the association between heavy metals and pan-cancer sex hormone levels among adults, 94,337 individuals from the National Health and Nutrition Examination Survey were assessed. We examined the associations between pan-cancers associated with sex hormones (ovarian, testicular, breast, and prostate cancers) and heavy metals in blood/urine. The methods (the WQS (weighted quantile sums) and SVYGLM (survey generalized linear model) regressions) were used to evaluate the association between sex hormone-related cancers and each metal category by incorporating covariates. To evaluate the overall effect of heavy metals and detect the dose-response relationship between the prevalence of pan-cancers associated with sex hormones and heavy metals, RCS (restricted cubic splines) were applied. Environmental exposure to heavy metals may be associated with pan-cancers associated with sex hormones in adults in the USA. Prostate cancer was inversely associated with blood cadmium while positively associated with blood lead, urinary tin, and thallium. Breast cancer was inversely associated with blood lead. Ovarian cancer was positively associated with blood cadmium. We also found a non-linear dose-response relationship between pan-cancers associated with sex hormones and heavy metals, which was non-parametric, using RCS models. The OR for breast cancer decreased along with the increase in lead concentration under approximately 20µg/dl, while the OR for prostate cancer increased between urine thallium levels of approximately 0.17-1.1ng/ml. Pan-cancers associated with sex hormones are associated with exposure to heavy metals. Considering the design of the NHANES study, further studies need to be conducted on other nationally representative surveys.

PbO-TeO2-MgO-Na2O-B2O3 glasses: Optical properties and gamma ray shielding behaviour studies using the Monte Carlo simulation

Melt quenching is used to make the PbO-TeO2-MgO-Na2O-B2O3 glasses. As lead concentration rises, so does density rise from 3.283 to 3.923 g/cm3. The indirect band gap values decrease from 3.262 to 3.111 eV as lead oxide increases. The refractive index (n), optical dielectric constant, and dielectric constant (ε) increase from 2.329 to 2.368, 4.428 – 4.606, and 5.428 – 5.606 with the increase in lead content. The metallization value of all the samples is less than unity which confirms the non-metallic nature of all samples. The partial replacement of B2O3 by PbO compounds affects also the shielding characteristics. The Monte Carlo simulation for the gamma-ray shielding parameters depicts that the linear attenuation coefficient (LAC) of the fabricated samples increases gradually with rising the B2O3 substitution ratio. For example, at 244 keV, the linear attenuation coefficient enhances by 51% with increasing PbO content. The increase in LAC was associated with a significant decrease in the half-value thickness, thickness equivalent, and transmission factor while the radiation protection efficiency of the fabricated samples was enhanced. Therefore, fabricated glasses are considered a better choice to be used in the radiation zones.

Микроэлементозы как предикторы иммунологических нарушений у детей с гипофункцией щитовидной железы, проживающих в районах с различным уровнем техногенного загрязнения

Aim: to assess relationship between the humoral immunity status and the amounts of chemical elements (CE) in schoolchildren with hypothyroidism living in the regions with different levels and characteristics of technogenic environmental pollution. Patients and Methods: this study included 340 children 4–7 years old. The children underwent medical examination in the kindergartens located in a rural area of Rostov Region; industrial district of Rostov-on-Don (hereinafter referred to as Rostov); Shakhty, a city located in the coal mining area of the region; and in a dacha village in Rostov suburbs located distantly from the industrial facilities. In the rural area 105 children (group 1) were examined, in Rostov City — 125 children (group 2), in Shakhty — 90 (group 3). Group 4 (control) included 20 healthy children living in a dacha village of Rostov suburbs. The authors analyzed the Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (Rospotrebnadzor) data characterizing the technogenic environmental pollution in the areas of residence of the studied children. Clinical laboratory tests were performed in all children. Results: such components of mineral fertilizers and pesticides as chlorides, nitrates, and phosphorus compounds prevailed among the technogenic contaminants in the rural regions. An intense xenogeneic burden was identified in the Rostov areas where kindergartens were located, while the highest xenogeneic burden was found in Shakhty. In groups 1, 2 and 3, free Т4 (fТ4) and free Т3 (fТ3) concentrations were lower than those in other groups. Moreover, the children of the first three groups had the highest thyrotropin (TSH) levels. In groups 1,2 and 3, serum IgM, IgG and total IgE levels were increased, and IgA level was decreased, while the most significant deviations from the normal values were found in the group 3 children who lived in the area with the highest adverse environmental impact. A positive statistically significant correlation was found between IgM and TSH levels (r=0,59, р=0,03) and between IgA и fТ4 levels (r=0.47, р=0.04). In addition, a negative statistically significant correlation was found between IgG и fТ4 levels (r=-0.49, р=0.04). In the group 1, 2 and 3 children, lead levels in the urine were higher than in the comparison group, and particularly high lead levels were detected in the group 3 children who lived in the area with the worst adverse environmental impact. In the same group, a positive statistically significant correlation was found between lead and TSH levels (r=0.62, р=0.02), between IgA and zinc (r=0.51, р=0.03), as well as between selenium and fТ4 (r=0.45, р=0.04). Also, a negative statistically significant correlation was determined between lead and fТ4 (r=-0.54, р=0.03) and between lead and IgA levels (r=-0.41, р=0.045). The ratio of selenium and lead in the group 3 children was significantly lower than in groups 1, 2 and 4. Conclusion: indicators demonstrating the intensity of humoral immunity were found in children with hypothyroidism, and the mostly pronounced pathological changes were reported in children living in the area with the highest technogenic environmental pollution. Reduced selenium and zinc levels along with increased lead concentrations in the morning sample of urine which correlated with decreased fТ4 and fТ3 levels in blood were found in children from the areas with adverse environmental conditions. KEYWORDS: thyroid, humoral immunity, chemical elements, microelementosis, iodine, iodine deficiency, xenogeneic burden. FOR CITATION: Popova V.A., Puzikova O.Z., Kozhin A.A. et al. Microelementoses as predictors of immunological disorders in children with hypothyroidism living in the regions with different levels of technogenic pollution. Russian Medical Inquiry. 2023;7(2):81–88 (in Russ.). DOI: 10.32364/2587-6821-2023-7-2-81-88.

Synthesis, structure and properties of PbO–PbF2–B2O3–SiO2 glasses

The structure, thermal and some physical properties of lead fluoroborate glasses containing 30 mol% SiO2 have been investigated by differential thermal analysis, X-ray diffraction and Fourier-transform infrared spectroscopy. The glasses were prepared by the conventional melt-quenching method. Fourier-transform infrared spectroscopy results showed that the network of these glasses consists mainly of BO3, BO4, SiO4, and PbO4 structural units. The thermal stability of the glass samples determined by differential thermal analysis was found to be about 80°C. Dilatometric measurements showed that the glass transition temperature and dilatometric softening temperature decrease with increasing lead content, whereas the coefficient of thermal expansion increases. The density and molar volume increased with the increase in lead content. The conductivity of the investigated glasses mainly depends on the mobility of F– and Pb2+ ions. The variation in volume resistance upon changing the composition has been correlated with the structural changes in the glass network. The results obtained in this study indicate that the investigated glasses can be potential candidates for advanced technologies as solder and sealing materials.

Regulation of three subtypes of SOD gene in Aleuroglyphus ovatus (Acari: Acaridae) under lead stress

Superoxide dismutase (SOD) is an important enzyme that acts as the first line of protection in the mite antioxidant defense system and involves in eliminating reactive oxygen species (ROS) under harsh environmental conditions. Lead pollution is becoming increasingly serious and poses a serious hazard to the health and survival and reproduction of organisms. Nevertheless, the SOD gene family was yet to be reported in stored grain pest mite (Aleuroglyphus ovatus). In the present study, A. ovatus was reared on artificial diets treated with different concentrations of lead (12.5, 25, 50 and 100 mg/kg); the treatment fed on artificial diet without lead was marked as the control group (CK). Then three different subtypes of SOD were cloned, including AoSOD1 (Cu-ZnSOD), AoSOD2 and AoSOD3 (MnSOD). Enzyme activity of the egg stage was the lowest, and that of the protonymph stage was the highest. The enzyme activity of A. ovatus increased initially before dropping with increasing lead concentration, nevertheless, it was still substantially higher than that in CK. The analysis of SOD enzyme activity specified that it was higher at 25 mg/kg lead in each mite stage compared to other concentration groups. All three genes were up-regulated and thereafter reduced in the embryonic stage, according to an examination of mRNA expression levels; tritonymphs, in particular, attained the highest level. The expression level of the SOD genes also changed with lead concentration. It increased after an initial decline trend with increasing lead concentration, and then peaked in the 100 mg/kg lead group, which were 3.1 times (AoSOD1), 4.1 times (AoSOD2), and 2.3 times (AoSOD3) the control group, respectively. In this study, three AoSOD genes had developmental stage-specific mRNA expressions, and the expression of SOD enzyme activity was encouraged by the higher lead concentration, and the mRNA expression level of the AoSODs genes was not synchronized with the enzyme activity.

Effects of lead pollution on bacterial communities in biofilm attached to submerged plants.

Submerged plants and biofilms have significant advantages in hydro-ecology rehabilitation, but their tolerance and physiological responses to heavy metal stress have thus far been under-investigated. This study investigated the influence of lead on physiological and biochemical responses, as well as variation in bacterial communities and functional characteristics of submerged plant biofilms. The results showed that chlorophyll a content of two submerged plants decreased with increased lead concentration. The concentration of malondialdehyde of both submerged plants was higher under high lead concentrations than under low lead concentrations, and the concentrations of malondialdehyde and hydrogen peroxide in Vallisneria natans were more stable. The antioxidant enzyme systems of the two plants played protective roles against lead stress. High lead concentration can inhibit the bacterial community and lead to decreased diversity. The most abundant bacterial phyla were Proteobacteria (40.9%), Cyanobacteria (21.5%), and Bacteroidetes (14.3%). Proteobacteria abundance decreased with increased lead concentration, while Cyanobacteria abundance increased. The lead concentration in plants (19.7%, P < 0.01) and the lead concentration in aquatic environment (17.7%, P < 0.01) were significantly correlated with variation in bacterial communities. High lead concentration inhibits the activity of these bacteria related to the conversion of nitrogen and sulfur.