Toxic Effects Of Heavy Metals Research Articles

Ameliorative Effect of Vernonia amygdalina Plant Extract on Heavy Metal-Induced Liver and Kidney Dysfunction in Rats.

Heavy metal toxicity contributes to liver and kidney dysfunction and damage through oxidative stress mechanisms; however, from previous studies, extracts from the Vernonia amygdalina plant have shown to possess potent antioxidant properties. This study was aimed at uncovering the potential ameliorative effects of ethanolic extract from Vernonia amygdalina plant in heavy metal toxicity-induced liver and kidney dysfunction. For this study, 44 Sprague Dawley rats were divided into three groups. The control group received a basal diet and water only while the treatment groups received varied dosages of the heavy metals. The copper (Cu) and lead (Pb) groups had five subgroups. The Cu only and Cu recovery subgroups were administered with 16 mg/kg Cu intraperitoneally daily for 14 days, whereas the Pb only and Pb recovery subgroups were administered with 13 mg/kg Pb intraperitoneally daily for 14 days. Subsequently, the Pb only and Cu only subgroups were sacrificed. The three Pb and Cu treatment subgroups received oral graded doses (100 mg/kg, 200 mg/kg, and 300 mg/kg) of the extract for 21 days. The Cu recovery and Pb recovery subgroups were left to recover for 21 days. After histological examinations, the Pb and Cu pretreatment groups showed evidence of focal necrosis accompanied by inflammatory cell infiltrations. The serum levels of liver biomarkers AST, ALT, and GGT, as well as urea and creatinine, were significantly elevated (P=0.01) following copper and lead exposure. Upon posttreatment of the rats with the extract, the physiological levels of the biomarkers were restored and tissue architecture of the organs improved. Thus, the ethanolic extract of Vernonia amygdalina is capable of ameliorating the effects of heavy metal toxicity through potent antioxidative mechanisms.

Salinity Influence on Copper Sulphate and Lead Nitrate Combined Toxicity Against <i>Oreochromis niloticus</i>

Brackish water ecosystems characterized by fluctuating physicochemical parameters are more susceptible to the toxic effects of heavy metals acting singly or jointly. This study investigated the effect of salinity variations on the joint action toxicity of copper sulphate (CuSO4) and lead nitrate Pb(NO3)2 against fingerlings of Oreochromis niloticus. Fingerlings were exposed to binary mixtures of CuSO4 and Pb(NO3)2 (ratios 1:1 and 1:4) at varying salinities (0‰, 2‰, 12‰ and 18‰) in laboratory bioassays. The binary mixtures of the heavy metals were least toxic to the fish at 12‰ with 96 h LC50 values of 115.558 mg l-1 and 198.274 mg l-1 compared to 8.465 mg l-1 and 16.884 mg l-1 for 0‰, 46.084 mg l-1 and 69.843 mg l-1 for 2‰ and 13.196mg l-1 and 100.567 mg l-1 for 18‰ at ratios 1:1 and 1:4 respectively. Analysis using the Synergistic Ratio Model (SR) showed that both heavy metals were less toxic to the fish species when acting jointly irrespective of ratio than when acting singly at 12‰. Therefore, the need to consider the fluctuating salinity and joint interaction of heavy metals in setting ecologically safe limits for the discharge of effluents containing heavy metals into the aquatic ecosystems is important.
 Key words: Salinity, Heavy Metals, Toxicity, Oreochromis niloticus

Progress in the Research of the Toxicity Effect Mechanisms of Heavy Metals on Freshwater Organisms and Their Water Quality Criteria in China

Water quality criteria are the scientific basis for formulating water quality standards and environmental management practices. Due to the development of urbanization and industrialization, the problem of heavy metal pollution has become a serious environmental problem. Heavy metals not only have major impacts on aquatic organisms, but also seriously threaten human health. However, the current environmental criteria refer to the maximum value limitations of environmental factors in environmental media where harmful or detrimental effects are not produced on specific protected objects. This study reviewed the sources, hazard levels, toxic effect mechanisms, and the current research status of China’s water quality criteria for heavy metal pollutants. In addition, the focus and direction of future research on the toxic effects of heavy metal on aquatic organisms and the necessary criteria changes were discussed. The present study would provide an important theoretical basis for the future research of water quality criteria and risk assessment of heavy metal pollutants.

Heavy metals-resistant bacteria (HM-RB): Potential bioremediators of heavy metals-stressed Spinacia oleracea plant

Microorganism technologies can provide a potential alternative to traditional methods of removing heavy metals to conserve agricultural soils. This study aimed to identify and characterize heavy metals-resistant bacteria (HM-RB) isolated from industry-affected soil and their desired impact as bioremediators of heavy metals-stressed spinach plants. Three of 135 isolates were selected based on a high level of resistance to heavy metals. Based on morphological and biochemical characteristics, the selected isolates were identified as Bacillus subtilis subsp. spizizenii DSM 15029T DSM (MA3), Paenibacillus jamilae DSM 13815T DSM (LA22), or Pseudomonas aeruginosa DSM 1117 DSM (SN36). Experiments were implemented to investigate the three isolated HM-RB ability on improving attributes of growth, physio-biochemistry, and components of the antioxidant defense system of spinach plant exposed to the stress of cadmium (Cd2+; 2mM), lead (Pb2+; 2mM) or 2mM Cd2++2mMPb2+. Compared to control, Cd2+ or Pb2+ stress markedly lowered plant fresh and dry weights, leaf contents of chlorophylls and carotenoids, rates of transpiration (Tr), net photosynthesis (Pn) and stomatal conductance (gs), relative water content (RWC), and membrane stability index (MSI). In contrast, contents of α.tochopherol (α.TOC), ascorbic acid (AsA), glutathione (GSH), proline, soluble sugars, Cd2+, and Pb2+, as well as activities of enzymatic and non-enzymatic antioxidants were markedly elevated. The application of HM-RB promoted the tolerance to heavy metal stress in spinach plants by improving Tr, Pn, gs, RWC, and MSI, while activities of enzymatic and non-enzymatic antioxidants were suppressed. These results reflected positively in promoting plant growth under heavy metal stress. Therefore, the application of HM-RB as potential bioremediators may be a promising strategy for promoting plant growth and productivity under heavy metal stress.

Protective effect of quercetin on rat testes against cadmium toxicity by alleviating oxidative stress and autophagy.

Cadmium (Cd), a highly toxic heavy metal, adversely affects human and animal health. Quercetin (Que) is a kind of flavonoid that can protect many tissues from the toxic effect of heavy metals. Although many studies have explored the adverse effects of cadmium on rats and other animals, the mechanism of Cd-induced testicular autophagy and the antagonistic effect of Que on cadmium remain unclear. In this study, Sprague-Dawley rats were treated with Cd, Que or Cd, and Que supplements to explore the mechanisms of Que-alleviated testis injury caused by Cd exposure. The rat body weight and relative testicular weight were measured. Morphological changes in testes and indices of oxidative stress were also examined. The expression levels of autophagy-related genes were detected as well. Results showed that Cd decreased the rat body weight and relative testicular weight and induced pathological changes in testes. Conversely, Que alleviated these changes. We also found that Cd increased the malondialdehyde content and decreased the contents of total superoxide dismutase, glutathione peroxidase, catalase, and glutathione. Moreover, the protein expression levels of P62 and LC3-II increased under Cd exposure conditions. Conversely, Que obviously alleviated these toxic activities induced by Cd. Overall, this study showed that Cd accumulated in rat testes, leading to oxidative stress and autophagy. Que can reduce cadmium toxicity by reducing oxidative stress and inhibiting autophagy. The specific mechanism of Que antagonizing Cd toxicity can provide new insights into countering cadmium toxicity.

Heavy metals stress, mechanism and remediation techniques in rice (Oryza sativa L.): A review

The rapid pace of urbanization and industrialization makes soil and environment polluted, which may cause a severe issue of food chain contamination. Discharge of heavy metal(oid)s from industrial and municipal wastewater streams, and groundwater contamination causes a reduction in crop yields, degradation of soils and ruin quality. Cultivated Asian rice and heavy metal(oid)s have two ways of interaction, either heavy metal(oid)s accumulation cause harmful effects on rice crop or rice plants possess their resistance mechanism to protect against the toxic effects of heavy metal(oid)s, their uptake, and translocation also detoxify the heavy metal(oids) contamination. Besides, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce/immobilize heavy metal(oid)s stress in rice. Selection/development of rice varieties resistant to heavy metals stress and bioaccumulation, crop rotation, water management and exogenous application of microbes could be a reasonable approach to alleviate heavy metal(oid)s toxicity in rice. This article review that heavy metals, such as aluminum, arsenic, cadmium, chromium, copper, mercury, and lead are the major environmental pollutants, mainly in the places having more significant anthropogenic pressure. In agricultural areas, accumulation of heavy metals is of primary concern because of their adverse effects. This review article also briefly discusses the impact of the heavy metals on human health, soil, plants, and their metabolic mechanisms induced by the biological and geological redistribution of heavy metals by soil and water pollution. Keywords: Accumulation; Dynamics; Heavy Metal(oids); Rice; Soil; Uptake http://dx.doi.org/10.19045/bspab.2020.90045

First draft genome for the sand-hopper Trinorchestia longiramus

Crustacean amphipods are important trophic links between primary producers and higher consumers. Although most amphipods occur in or around aquatic environments, the family Talitridae is the only family found in terrestrial and semi-terrestrial habitats. The sand-hopper Trinorchestia longiramus is a talitrid species often found in the sandy beaches of South Korea. In this study, we present the first draft genome assembly and annotation of this species. We generated ~380.3 Gb of sequencing data assembled in a 0.89 Gb draft genome. Annotation analysis estimated 26,080 protein-coding genes, with 89.9% genome completeness. Comparison with other amphipods showed that T. longiramus has 327 unique orthologous gene clusters, many of which are expanded gene families responsible for cellular transport of toxic substances, homeostatic processes, and ionic and osmotic stress tolerance. This first talitrid genome will be useful for further understanding the mechanisms of adaptation in terrestrial environments, the effects of heavy metal toxicity, as well as for studies of comparative genomic variation across amphipods.

Protective role of selenium in the shortening of telomere length in newborns induced by in utero heavy metal exposure

The effects of toxic heavy metals, such as arsenic (As), cadmium (Cd), and lead (Pb), on telomere length (TL) have been reported previously. Although selenium (Se) is considered as an anti-oxidant which may detoxify the effects, there are no data on whether Se could protect against the TL-shortening effects of heavy metals. Thus, the aim of this study was to evaluate the protective role of Se against heavy metal-induced TL shortening. A birth cohort study was conducted in Myanmar in 2016, including 408 mother-infant pairs. First, pregnant women in the third trimester were interviewed concerning their socioeconomic, and pregnancy and birth characteristics using a pre-validated questionnaire. Maternal spot urine samples were collected after the interview. During the follow-up period (1–3 months), blood samples were collected from the umbilical cord at birth by local health workers. Metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). TL was measured by quantitative real-time polymerase chain reaction (PCR). Relative TL was calculated as the ratio of telomere genes to single-copy genes. To evaluate the effect of Se on TL shortening, molar ratios were calculated. Linear regression analyses were performed to examine the associations between heavy metals and TL, individually and after adjustment for Se level. The effects of As, Cd, and Pb exposure on TL were smaller after adjustment for the Se level, especially for Pb (unadjusted β = −0.10; 95% CI: 0.18, −0.01; adjusted β = −0.03; 95% CI: 0.13, 0.05). On stratifying the data by Se concentration, there was no significant association between Cd or Pb exposure and TL in the high-Se group. Our study indicated a protective effect of Se against the TL shortening induced by heavy metal exposure, where the effect sizes were smaller after adjusting for the Se level, compared to individual metal exposure.

Co-occurrence of functionally diverse bacterial community as biofilm on the root surface of Eichhornia crassipes (Mart.) Solms-Laub

The current study investigates the functional diversity of bacterial community existing as a biofilm on the root surface of water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.) grown in Yamuna river, Delhi, India. Forty-nine bacterial isolates recorded a diverse pattern of susceptibility/resistance to 23 antibiotics tested. Most of the bacterial isolates were susceptible to Ofloxacin, Ciprofloxacin, Ceftriaxone, Gentamicin, and Cefepime and resistant to Ceftazidime, Nitrofurantoin, Ampicillin, and Nalidixic acid. Isolate RB33-V recorded resistant against 11 antibiotics tested, and RB42-V was found susceptible to most of the antibiotics tested. Among the seven heavy metals tested, the highest of 39 bacteria showed resistance to zinc, and least of 9 bacteria recorded resistance against cadmium. Isolate RB20-III was susceptible to all heavy metals tested, and RB23-III was found resistance for six heavy metals tested. A higher correlation was observed with zinc and multiple antibiotic resistance, and Ceftazidime resistance was most frequently associated with all the heavy metals tested. These bacteria grow optimally under neutral-alkali conditions and susceptible to acidic conditions, and they can withstand a broad range of temperatures and salt concentrations. They are very poor in phosphate solubilization. Further, the bacteria recorded varied results for beneficial traits, hemolytic, and DNase activity. The results of bacterial characterization indicated that this bacterial community is of multi-origin in nature and are assisting the host-plant in withstanding the adverse and fluctuating conditions of the Yamuna river by reducing the toxic effect of heavy metals, antibiotics and other xenobiotics.

CARDIOVASCULAR TOXICITY IN COPPER PRODUCTION WORKERS EXPOSED TO HEAVY METALS

Introduction. Cardiovascular diseases (CVD) are a leading cause of morbidity and mortality. The role of occupational hazards in the CVD prevalence remains to be clarified. Material and methods. Here we report the results of the study of risk factors and CVD prevalence in 590 workers at the largest copper production plants in the Sverdlovsk region, exposed to heavy metals in the workplace. The workers` health information was obtained during a regular medical examination in 2018. The lead concentration increase to 1.3-1.8 occupational exposure limits was registered in the working areas of the concentrating mill (for bunkerman) and copper smelting workshops (transporter, smelter, converter, non-ferrous metal spreader, repairman, electrician). Results. We studied the exposure indices (Pb level in blood), the response markers (reticulocyte count, erythrocytes basophilic stippling, coproporphyrin, and aminolevulinic acid in the urine), and their correlation to a working tenure. Based on this analysis, we attributed CVD risk factors and cardiovascular diseases to the occupation, in order to potentially modify some of those risk factors and ultimately inform the risk management. Hypertension occurred in 57% of the examined workers, which is higher than in the general population. We calculated relative risk, confidence intervals and attributable fraction. We developed a predictive mathematical model (stepwise logistic regression) to predict high-stage hypertension and identified the risk factors associated with its development. Conclusions. Correlation analysis revealed direct correlations between stages 2 and 3 hypertension and a working tenure over 20 years. We think it’s reasonable to consider the documented CVDs as related to the toxic effects of heavy metals (lead and cadmium).

Bioremediation approach using charophytes-preliminary laboratory and field studies of mine drainage water from the Mansfeld Region, Germany.

Mine drainage water from the Schlenze stream, Mansfeld Region, Central Germany, which have shown an increase in heavy metal concentrations of Cd2+, Cu2+, Pb2+, and Zn2+, was used to investigate the bioremediation potential of charophytes. The removal of heavy metals by Chara subspinosa from the water was tested in single- and multi-metal additions. The uptake capacity of C. subspinosa decreased during the course of the experiment and was higher in single-metal addition than in multi-metal addition of Pb2+, Zn2+, and Cd2+. Accumulation of heavy metals in the carbonate encrustation of charophytes was far lower than those to which they were exposed. Cu, Cd, Pb, and Zn co-precipitated more in the encrustation of C. subspinosa exposed to single-metal approach than to multi-metal approach. The carbonate composition of charophytes was influenced by the water chemistry. Content of Na in the carbonate encrustation correlated with the Na+ concentration of the respective water. The toxic effect of heavy metals on photosynthesis was species-specific. Electron transport rates (ETRmax) were higher in Chara tomentosa than in C. subspinosa. Charophytes withstand the heavy metal concentrations when diluted with river water from the Altarm cut-off lake and can therefore be used for the bioremediation of diluted mine drainage waters by co-precipitating Cd, Cu, and Zn.

Copper and zinc distribution and toxicity in ‘Jade’ / ‘Genovesa’ young peach tree

The frequent application of fungicides containing copper (Cu) and zinc (Zn) in orchards can lead to accumulation of these metals in soil at toxic levels. The aim of this study was to evaluate Cu and Zn distribution and toxicity in young peach trees grown in Cu and Zn supplemented soil. For this purpose, a pot experiment was carried out in a greenhouse using a Typic Hapludalf soil under natural conditions. The two-factor experiment investigated the combination of Cu (0, 30 and 60 mg kg−1) and Zn (0, 15, 30, 60, 120, and 180 mg kg−1) rates in four replicates per treatment. ‛Jade’ young peach trees [Prunus persica (L.) Batsch] grafted on ‛Genovesa’ (P. salicina) propagated by herbaceous cuttings were then cultivated for 78 days with one plant per pot. Height increase, dry matter production, Cu and Zn concentration in plant organs, photosynthetic pigments and antioxidant activity were evaluated. Soil available Cu and Zn content increased with the rate. Consequently, plants presented Zn, and mainly Cu, accumulation mechanisms in root system, reduced transport of both elements to leaves, where toxic effects of heavy metals was observed. However, combining high content of soil available Cu and Zn, especially at higher doses, resulted in decreased production of dry matter production. Biochemical parameters were also affected. The SOD activity was smaller in peach leaves grown in the soil supplemented with Cu, while the chlorophyll a and b content decreased according to the increase of Zn rate, compromising the antioxidant response and the photosynthetic activity. Thus, increasing soil available Cu and Zn contents in sandy soil with low organic matter soils may maximize toxic effects to young peach trees.

INDICATION OF WATER POLLUTION WITH HEAVY METALS BY MEANS OF CYANOBACTERIA SYNECHOCYTIS SP

The sensitivity of cyanobacteria to heavy metal salts under different cultivation conditions has been investigated. It is shown that the decrease in temperature and the lack of illumination of the environment increase the toxic effect of heavy metals. Data on morphological changes of cyanobacteria caused by toxic effects of heavy metals are presented. It is noted that cyanobacteria can be used as an experimental model to study the toxicity of heavy metals in the testing of water and soil pollution.

The Effect of Heavy Metal Toxicity on Pollen Viability and Pollen Tupe Growth in Red Chief and Granny Smith Apple Cultivars

Bitkilerde, tozlaşma ve döllenme, çevresel faktörlerden etkilenen önemli bir olaydır. Polen çimlenmesi ve polen tüpü büyümesi boyunca bitkilerin hassasiyeti artmakta ve çevresel kirliliğe karşı bitkilerin generatif organları vejetatif kısımlarından daha duyarlıdır. Bu nedenle de metal toksisitesi ve gübreleme gibi uygun olmayan koşullardaki tozlaşma ve dolayısıyla meyve tutumu olumsuz etkilenmektedir. Bu çalışmada, farklı ağır metal dozlarının (Cd, Co, Pb, Hg ve Zn) Red Chief ve Granny Smith elma çeşitlerindeki polen çimlenmesi ve tüp büyümesi üzerine etkisi araştırılmıştır. Çeşitlerin polen canlılığı oranları TTC (2-3-5-trifeniltetrazoliumklorid) canlılık testi ile belirlenmiş ve ortalama canlılık oranları Red Chief çeşidinde % 84.4 Granny Smith çeşidinde ise %75.4 olarak belirlenmiştir. Bununla birlikte, çeşitler hem ağır metaller hem de doz uygulamasından önemli ölçüde etkilenmiştir. Çeşitlerin polen çimlenmesi ve tüp uzunluğu metal dozunun artışına bağlı olarak düşüş göstermiştir. Elma çeşitlerinde polen çimlenmesi ve tüp uzunluğu üzerine en yüksek engelleyici etkiyi civa (Hg) düşük etkiyi ise kobalt (Co) göstermiştir.

Role of arsenic, lead and cadmium on telomere length and the risk of carcinogenesis: a mechanistic insight

Integrity of telomeres, the protective structures that cap the ends of eukaryotic chromosomes are crucial for the maintenance of chromosomal integrity and cell survival. Loss in telomere length homeostasis is a hallmark of various disease manifestations including cancer. Environmental or occupational exposure to heavy metal contaminants is known to disrupt this homeostasis. This study aims to substantiate the effects of heavy metal toxicity, particularly three heavy metal toxicants: arsenic, lead and cadmium on telomere length and to comprehend the mechanistic insights in depth. The mechanisms involved in telomere length alterations in response to heavy metal toxicity are still not clearly understood. Recent studies indicate epigenetic de-regulations in response to heavy metal toxicity and interestingly, telomere length is also regulated by epigenetic modifications. Environmental exposure induced epigenetic alterations might be one of the mechanism involved in telomere dysfunction. Telomeres are a prognostic marker in carcinogenesis, and hence further in-depth studies are indeed important in this field for future therapeutic purposes.

Increased oxidative stress in cadmium toxicity

Sustainable and cost-effective methods are required to increase the food production and decrease the toxic effects of heavy metals. Most of the agriculture land is contaminated with cadmium (Cd). The present study was designed to minimize the toxic effect of Cd stress (0, 10 and 20 mg kg1−) on tolerant and sensitive varieties of wheat (Punjab-2011; Sammar) and rice (Kisan Basmati; Chenab) under Zn-lysine (Zn-lys) application as foliar spray (0, 12.5 and 25 mM) and seed priming (0, 3 and 6 ppm). Remarkable decrease was observed in plant growth, physiology and biochemistry as well as increase in Cd uptake, roots to shoots and grains of both crops. Cd significantly reduced the root and shoot lengths, root and shoot dry weights, transpiration rate, photosynthetic rate, stomatal conductance and water use efficiency as well as chlorophyll contents associated with enhanced electrolyte leakage (EL), malondialdehyde (MDA) and H2O2 and Cd uptake in different plant parts including grains of both crop varieties. The foliar application of Zn-lys (0, 12.5 and 25 mM) ameliorated the toxic effect of Cd on growth and physiology associated with decrease in EL, MDA and H2O2 and improved the activities of SOD, POD, CAT and APX enzymes with decreasing Cd uptake in tolerant varieties of wheat and rice as compared to seed priming. Furthermore, it has been investigated that the foliar application of Zn-lys is effective to improve quality of wheat and rice tolerant varieties (Punjab-2011 and Chenab) under Cd contamination soils.

Alleviative effects of dietary Indian lotus leaves on heavy metals-induced hepato-renal toxicity, oxidative stress, and histopathological alterations in Nile tilapia, Oreochromis niloticus (L.)

Heavy metals (HM) are widespread contaminants of water affecting aquatic organisms and aquatic ecosystems. Indian lotus, Nelumbo nucifera (Gaertn.), is a beneficial medicinal plant that exhibits several pharmacological properties. It is hypothesized that incorporation of Indian lotus leaf (ILL) powder may be able to alleviate toxic effects exerted by a mixture of lead (Pb), cadmium (Cd), mercury (Hg), and zinc (Zn) in Nile tilapia, Oreochromis niloticus (L.). A total of two hundred and forty fish were randomly allocated into eight groups in triplicate, in a bifactorial design (4 ILL levels × 2 HM exposures). The fish in the first four groups were fed on a basal diet (39.9% crude protein) that was enriched with 0.0, 0.1, 0.2, and 0.4% ILL (in G1–G4, respectively), with no HM exposure. In the remaining four groups, fish were fed with the same diets and, in addition, were exposed to 1/20 of the 96 h-LC50 of Pb, Cd, Hg, and Zn mixture (in G5–G8, respectively), for 45 days. The HM exposure significantly elevated the levels of serum alanine and aspartate aminotransferases, creatinine, urea, malondialdehyde, and activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). The expression level of hepatic metallothionein (MT) was up-regulated as well as high residual levels of HM in fish musculature were recorded in the HM-exposed fish. Two-way ANOVA revealed that all the studied variables were significantly affected by the ILL supplementation, HM exposure, and their interaction. Moreover, levels of MDA, CAT, SOD, and MT showed significant positive correlations with HM concentrations. Moreover, necrosis and degeneration of hepatopancreatic cells with congestion, hyperplasia, and fusion of gills lamellae were observed in HM-exposed fish. Interestingly, ILL supplementation, especially in the fish fed with 0.2 and 0.4% ILL, was observed to reduce the HM concentration in the fish body, resulting in the reduction of its toxic effects on the biochemical and antioxidant activities. These results demonstrated that dietary ILL supplementation could protect Nile tilapia against the toxic effects of HM, and therefore, may serve as a beneficial feed additive for application in the aquaculture industry.

Possible role of HMA4a TILLING mutants of Brassica rapa in cadmium phytoremediation programs

Cadmium (Cd) is a dangerous transition element that causes environmental and health problems due to its high mobility in the soil-plant system. In plants, Cd causes serious alterations in physiological processes, affecting different vital functions such as photosynthesis. Species such as Brassica juncea and Brassica rapa have been selected as suitable plants for phytoremediation purposes due to their ability to tolerate the toxic effect of heavy metals. In order to improve this strategy, techniques of plant mutagenesis such as TILLING (Targeting Induced Local Lessions in Genomes) have been employed. In the present work we studied the role of the HMA4 gene in the tolerance to Cd toxicity (100 μM CdCl2) using a TILLING mutant of B. rapa (BraA.hma4a-3). These mutant plants presented a lower biomass reduction and a higher Cd concentration in leaves. An increase in the GSH/GSSG ratio, in the content of photosynthetic pigments and a reduction of oxidative stress was observed, as well as a better photosynthetic index, confirming that BraA.hma4a-3 plants showed a higher tolerance to Cd. In conclusion, according to the results obtained in this work, BraA.hma4a-3 plants could be used for phytoremediation purposes of Cd contaminated soils.

Probing the binding effects of zinc and cadmium with garlic phytocystatin: Implication of the abiotic stress on garlic phytocystatin.

Abiotic stress induced by heavy metals retards the growth and development of plants. Therefore, it is essential to have an insight into the potential toxic effects of heavy metals. The present article investigates the effect of zinc and cadmium on the structure and function of garlic phytocystatin (GPhyCys). The cysteine proteinase inhibitory assay showed a reduction in the inhibitory activity upon binding with zinc and cadmium. UV-vis absorption spectroscopy revealed the complex formation of zinc and cadmium with garlic phytocystatin. Fluorescence quenching experiment confirmed the quenching of fluorophores upon binding of zinc and cadmium. Synchronous and 3-dimensional fluorescence spectroscopy suggest the alteration in the microenvironment around aromatic residues of garlic phytocystatin upon binding with the above metals. Circular dichroism showed a reduction in the alpha-helical content of native garlic phytocystatin. Scanning electron micrographs showed the morphological changes in the native garlic phytocystatin upon addition of zinc and cadmium. The observations confirmed the alteration in structure and conformation of garlic phytocystatin upon interaction with zinc and cadmium. It can be safely concluded that the high concentration of zinc and cadmium can alter the functioning of cysteine proteinase present in garlic and affects the growth and development of plants.

Efficiency of heavy metals-tolerant plant growth promoting bacteria for alleviating heavy metals toxicity on sorghum

A green-house experiment was conducted to investigate the efficiency of three heavy metal-tolerant plant growth promoting bacterial strains (HMT-PGPB) (Alcaligenes faecalis MG257493.1, Bacillus cereus MG257494.1 and Alcaligenes faecalis MG966440.1 to alleviate the heavy metal’s toxic effects on sorghum plant (Sorghum bicolor, L.) in addition to their ability to enhance plant growth. The oxidative enzymes, photosynthetic pigments, growth characteristics, heavy metals uptake and heavy metals translocation factor (TF) were estimated in sorghum cultivated in soil contaminated with heavy metals under green-house conditions. Results showed that the application of these HTM-PGPB strains as biofertilizer of sorghum help plant to ignore the toxic effects of heavy metals and enhance growth characteristics.