scholarly journals Ancestral function of the phytochelatin synthase C-terminal domain in inhibition of heavy metal-mediated enzyme overactivation

2020 ◽  
Vol 71 (20) ◽  
pp. 6655-6669
Author(s):  
Mingai Li ◽  
Enrico Barbaro ◽  
Erika Bellini ◽  
Alessandro Saba ◽  
Luigi Sanità di Toppi ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Resistance ◽  
Enzyme Activation ◽  
Site Directed Mutagenesis ◽  
Metal Exposure ◽  
Marchantia Polymorpha ◽  
Terminal Domain ◽  
C Terminus ◽  
Ancestral Function

Abstract Phytochelatin synthases (PCSs) play essential roles in detoxification of a broad range of heavy metals in plants and other organisms. Until now, however, no PCS gene from liverworts, the earliest branch of land plants and possibly the first one to acquire a PCS with a C-terminal domain, has been characterized. In this study, we isolated and functionally characterized the first PCS gene from a liverwort, Marchantia polymorpha (MpPCS). MpPCS is constitutively expressed in all organs examined, with stronger expression in thallus midrib. The gene expression is repressed by Cd2+ and Zn2+. The ability of MpPCS to increase heavy metal resistance in yeast and to complement cad1-3 (the null mutant of the Arabidopsis ortholog AtPCS1) proves its function as the only PCS from M. polymorpha. Site-directed mutagenesis of the most conserved cysteines of the C-terminus of the enzyme further uncovered that two twin-cysteine motifs repress, to different extents, enzyme activation by heavy metal exposure. These results highlight an ancestral function of the PCS elusive C-terminus as a regulatory domain inhibiting enzyme overactivation by essential and non-essential heavy metals. The latter finding may be relevant for obtaining crops with decreased root to shoot mobility of cadmium, thus preventing its accumulation in the food chain.

scholarly journals Relationship between heavy metal exposure and type 2 diabetes: a large-scale retrospective cohort study using occupational health examinations

BMJ Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. e039541
Author(s):  
Jun Ho Ji ◽  
Mi Hyeon Jin ◽  
Jung-Hun Kang ◽  
Soon Il Lee ◽  
Suee Lee ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Type 2 Diabetes ◽  
Heavy Metal ◽  
Cohort Study ◽  
Retrospective Cohort ◽  
Metal Exposure ◽  
Heavy Metal Exposure ◽  
Lead And Cadmium

ObjectivesTo investigate the associations between heavy metal exposure and serum ferritin levels, physical measurements and type 2 diabetes mellitus (DM).DesignA retrospective cohort study.SettingChangwon, the location of this study, is a Korean representative industrial city. Data were obtained from medical check-ups between 2002 and 2018.ParticipantsA total of 34 814 male subjects were included. Of them, 1035 subjects with lead exposure, 200 subjects with cadmium exposure and the 33 579 remaining were assigned to cohort A, cohort B and the control cohort, respectively. Data including personal history of alcohol and smoking, age, height, weight, the follow-up duration, haemoglobin A1c (HbA1c), fasting blood sugar (FBS), ferritin levels, and lead and cadmium levels within 1 year after exposure were collected.Primary outcome measureIn subjects without diabetes, changes in FBS and HbA1c were analysed through repeated tests at intervals of 1 year or longer after the occupational exposure to heavy metals.ResultsIn Cohort A, DM was diagnosed in 33 subjects. There was a significant difference in lead concentrations between the subjects diagnosed with DM and those without DM during the follow-up period (3.94±2.92 mg/dL vs 2.81±2.03 mg/dL, p=0.002). Simple exposure to heavy metals (lead and cadmium) was not associated with DM in Cox regression models (lead exposure (HR) 1.01, 95% CI: 0.58 to 1.77, p 0.971; cadmium exposure HR 1.48, 95% CI: 0.61 to 3.55, p=0.385). Annual changes in FBS according to lead concentration at the beginning of exposure showed a positive correlation (r=0.072, p=0.032).ConclusionOur findings demonstrated that simple occupational exposure to heavy metals lead and cadmium was not associated with the incidence of DM. However, lead concentrations at the beginning of the exposure might be an indicator of DM and glucose elevations.

Screening of heavy metal and antibiotic resistance among Proteus vulgaris isolates from hospital wastewater of Northern India

2021 ◽  
Vol 19 ◽  
Author(s):  
Manzar Alam ◽  
Mohd Imran ◽  
Syed Sayeed Ahmad
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Multiple Drug Resistance ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Antibiotics Resistance ◽  
Proteus Vulgaris ◽  
Resistance To Antibiotics ◽  
Transfer Frequency ◽  
Resistance Patterns

Background: Microbial resistance to antibiotics and heavy metals is a rising problem in the world today. All the Proteus vulgaris isolates showed their MIC in between 50-1600 µg/ml. Of 70% and 46% of the isolates showed their MIC at 800-1200 µg/ml against Zn2+ and Cu2+ while 80% of the isolates showed their MIC at 100-200 µg/ml against Ni2+, respectively. All Proteus vulgaris isolates also exhibited multiple resistance patterns (2-7 heavy metals) in different combination of metals. The Multi metal resistance Index (MHMR) ranges were found (0.04-0.5). Methods: A high level of antibiotics resistance was observed against Methicillin (100%) and least to Oflaxicin (6%), Gentamycine and Neomycin (10%). All Proteus vulgaris isolates also showed multiple drug resistance patterns (2-12 antibiotics) in different combination of antibiotics. The MAR index ranges were found (0.02-0.7). Of 98%, 84% and 80% of the total isolates showed urease, gelatinase and amylase activity. Results: The Proteus vulgaris isolates contained plasmid of size ranging from 42.5 to 57.0kb and molecular weight of plasmids ranged from 27.2 to 37.0 MD. Incidences of resistance transfer, 7 pairs of isolates were assessed for the transfer of the antibiotic/ heavy metal resistance markers. The higher (4.4x10-1 and 3.4x10-1) transfer frequency was observed among antibiotic and heavy metal while lower transfer frequency were (5.0x10-2 and 1.0x10-2) showed against antibiotic and heavy metal in both the medium from the entire site tested, respectively. Conclusion: Indicating the high threat of environmental pollution and appearance of heavy metal resistance which may support the enlargement of resistance to antibiotics among the pathogens.

scholarly journals TINGKAT BIOKONSENTRASI LOGAM BERAT DAN GAMBARAN HISTOPATOLOGI IKAN MUJAIR (Oreochromis Mossambicus) YANG HIDUP DI PERAIRAN TUKAD BADUNG KOTA DENPASAR

2015 ◽  
Vol 9 (1) ◽  
pp. 25
Author(s):  
Made Rahayu Kusumadewi ◽  
I Wayan Budiarsa Suyasa ◽  
I Ketut Berata
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Hexavalent Chromium ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Quality Standards ◽  
Oreochromis Mossambicus ◽  
Metal Exposure ◽  
Histopathological Changes ◽  
Food Ingredient

Tukad Badung River is one of the potential contamination of heavy metal sare very highin the city of Denpasar. Tilapia (Oreochromis mossambicus) isa commonspecies of fish found in the river and became the object of fishing by the public. The fish is usually consume das a food ingredient forever yangler. Fish can be used as bio-indicators of chemical contamination in the aquatic environment. Determination of heavy metal bioconcentration and analysis of liver histopathology gills organs and muscles is performed to determine the content of heavy metals Pb, Cd, and Cr+6, and the influence of heavy metal exposure to changes in organ histopathology Tilapia that live in Tukad Badung. In this observational study examined the levels of heavy metal contamination include Pb, Cd and Cr+6 in Tilapia meat with AAS method (Atomic Absorption Spectrofotometric), and observe the histopathological changes in organ preparations gills, liver, and muscle were stained with HE staining (hematoxylin eosin). Low Pb content of the fish that live in Tukad Badung 0.8385 mg/kg and high of 20.2600 mg/kg. The content of heavy metals Pb is above the quality standards specified in ISO 7378 : 2009 in the amount of 0.3 mg / kg. The content of Cr+6 low of 1.1402 mg / kg and the highest Cr+6 is 6.2214 mg / kg. The content of Cr+6 is above the quality standards established in the FAO Fish Circular 764 is equal to 1.0 mg / kg. In fish with Pb bioconcentration of 0.8385 mg / kg and Cr+6 of 1.1402 mg / kg was found that histopathological changes gill hyperplasia and fusion, the liver was found degeneration, necrosis, and fibrosis, and in muscle atrophy found. Histopathologicalchangessuch asedema and necrosis ofthe liveris foundin fishwith Pb bioconcentration of 4.5225mg/kg and Cr+6 amounted to2.5163mg/kg. Bio concentration of heavy metal contamination of lead (Pb) and hexavalent chromium (Cr+6) on Tilapia ( Oreochromis mossambicus ) who lives in Tukad Badung river waters exceed the applicable standard. Histopathological changes occur in organs gills, liver, and muscle as a result of exposure to heavy metals lead and hexavalent chromium. Advised the people not to eat Tilapia that live in Tukad Badung

scholarly journals A Review on the Resistance and Accumulation of Heavy Metals by Different Microbial Strains

2022 ◽  
Author(s):  
Madhuri Girdhar ◽  
Zeba Tabassum ◽  
Kopal Singh ◽  
Anand Mohan
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Volcanic Eruptions ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Contaminated Sites ◽  
Bacillus Species ◽  
Polluted Sites ◽  
Pollution Accumulation ◽  
Microbial Strains

Heavy metals accumulated the earth crust and causes extreme pollution. Accumulation of rich concentrations of heavy metals in environments can cause various human diseases which risks health and high ecological issues. Mercury, arsenic, lead, silver, cadmium, chromium, etc. are some heavy metals harmful to organisms at even very low concentration. Heavy metal pollution is increasing day by day due to industrialization, urbanization, mining, volcanic eruptions, weathering of rocks, etc. Different microbial strains have developed very efficient and unique mechanisms for tolerating heavy metals in polluted sites with eco-friendly techniques. Heavy metals are group of metals with density more than 5 g/cm3. Microorganisms are generally present in contaminated sites of heavy metals and they develop new strategies which are metabolism dependent or independent to tackle with the adverse effects of heavy metals. Bacteria, Algae, Fungi, Cyanobacteria uses in bioremediation technique and acts a biosorbent. Removal of heavy metal from contaminated sites using microbial strains is cheaper alternative. Mostly species involved in bioremediation include Enterobacter and Pseudomonas species and some of bacillus species too in bacteria. Aspergillus and Penicillin species used in heavy metal resistance in fungi. Various species of the brown algae and Cyanobacteria shows resistance in algae.

scholarly journals Heavy Metal Sorption by Sludge-Derived Biochar with Focus on Pb2+ Sorption Capacity at μg/L Concentrations

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1559
Author(s):  
Ida Sylwan ◽  
Hanna Runtti ◽  
Lena Johansson Westholm ◽  
Henrik Romar ◽  
Eva Thorin
Keyword(s):  
Experimental Data ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Sorption Capacity ◽  
Municipal Wastewater ◽  
Metal Removal ◽  
Metal Exposure ◽  
Isotherm Models ◽  
Metal Sorption ◽  
Heavy Metal Sorption

Municipal wastewater management causes metal exposure to humans and the environment. Targeted metal removal is suggested to reduce metal loads during sludge reuse and release of effluent to receiving waters. Biochar is considered a low-cost sorbent with high sorption capacity for heavy metals. In this study, heavy metal sorption to sludge-derived biochar (SDBC) was investigated through batch experiments and modeling and compared to that of wood-derived biochar (WDBC) and activated carbon (AC). The aim was to investigate the sorption efficiency at metal concentrations comparable to those in municipal wastewater (<1 mg/L), for which experimental data are lacking and isotherm models have not been verified in previous works. Pb2+ removal of up to 83% was demonstrated at concentrations comparable to those in municipal wastewater, at pH 2. SDBC showed superior Pb2+ sorption capacity (maximum ~2 mg/g at pH 2) compared to WDBC and AC (<0 and (3.5 ± 0.4) × 10−3 mg/g, respectively); however, at the lowest concentration investigated (0.005 mg/L), SDBC released Pb2+. The potential risk of release of other heavy metals (i.e., Ni, Cd, Cu, and Zn) needs to be further examined. The sorption capacity of SDBC over a metal concentration span of 0.005–150 mg Pb2+/L could be predicted with the Redlich–Peterson model. It was shown that experimental data at concentrations comparable to those in municipal wastewater are necessary to accurately model and predict the sorption capacity of SDBC at these concentrations.

scholarly journals Maternal Heavy Metal Exposure, Thyroid Hormones, and Birth Outcomes: A Prospective Cohort Study

2019 ◽  
Vol 104 (11) ◽  
pp. 5043-5052 ◽  
Author(s):  
Xiaojie Sun ◽  
Wenyu Liu ◽  
Bin Zhang ◽  
Xiantao Shen ◽  
Chen Hu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Thyroid Hormones ◽  
Birth Outcomes ◽  
Metal Exposure ◽  
Birth Size ◽  
Heavy Metal Exposure ◽  
Mediation Analyses ◽  
Maternal Thyroid

AbstractContextMaternal thyroid hormones during pregnancy play a critical role in fetal development. However, whether maternal heavy metal exposure affects their thyroid hormones and the effects on fetal growth are still unclear.ObjectiveTo explore the effect of heavy metal exposure on maternal thyroid hormones and the potential mediation role of thyroid hormones on birth outcomes.MethodsConcentrations of heavy metals in urine samples and thyroid hormones in blood samples of 675 pregnant women were measured during early pregnancy in a cohort study conducted in China. Multivariable linear regressions were applied to explore the associations of maternal urinary heavy metal levels with both maternal thyroid hormones and birth outcomes. Mediation analyses were performed to assess the mediation role of thyroid hormones in these associations.ResultsMaternal urinary vanadium (V) exhibited an inverse association with free T3 (FT3) and FT3/free T4 (FT4) ratio levels. Urinary arsenic (As) and lead (Pb) had inverse relationships with FT3. We also observed the positive associations of maternal FT3 and FT3/FT4 ratio with birthweight. The mediation analyses suggested that 5.33% to 30.57% of the associations among V, As, and Pb levels and birth size might be mediated by maternal FT3 or FT3/FT4 ratio.ConclusionsWe have shown that maternal exposures to V, As, and Pb at early pregnancy were associated with decreased maternal FT3 or FT3/FT4 ratio, which might contribute to reduced birthweight. Mediation analyses indicated that maternal thyroid hormone was a possible mediator of the association between urinary heavy metals and birth size.

scholarly journals Derivation of Predicted No Effect Concentrations (PNECs) for Heavy Metals in Freshwater Organisms in Korea Using Species Sensitivity Distributions (SSDs)

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 697
Author(s):  
Jinhee Park ◽  
Sang Don Kim
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Gumbel Distribution ◽  
Cumulative Distribution ◽  
Metal Exposure ◽  
Suitable Model ◽  
Toxicity Data ◽  
Species Sensitivity ◽  
Distribution Models ◽  
Freshwater Organisms

Natural and artificial heavy metal exposure to the environment requires finding thresholds to protect aquatic ecosystems from the toxicity of heavy metals. The threshold is commonly called a predicted no effect concentration (PNEC) and is thought to protect most organisms in an ecosystem from a chemical. PNEC is derived by applying a large assessment factor (AF) to the toxicity value of the most sensitive organism to a chemical or by developing a species sensitivity distribution (SSD), which is a cumulative distribution function with many toxicity data for a chemical of diverse organisms. This study developed SSDs and derived PNECs using toxicity data of organisms living in Korea for four heavy metals: copper (Cd), cadmium (Cu), lead (Pb), and zinc (Zn). Five distribution models were considered with log-transformed toxicity data, and their fitness and uncertainty were investigated. As a result, the normal distribution and Gumbel distribution fit the data well. In contrast, the Weibull distribution poorly accounted for the data at the lower tails for all of the heavy metals. The hazardous concentration for 5% of species (HC5) derived from the most suitable model for each heavy metal was calculated to be the preferred PNEC by AF 2 or AF 3. PNECs, obtained through a suitable SSD model with resident species and reasonable AF, will help protect freshwater organisms in Korea from heavy metals.

scholarly journals Isolation and Molecular Identification of Virulence, Antimicrobial and Heavy Metal Resistance Genes in Livestock-Associated Methicillin-Resistant Staphylococcus aureus

Pathogens ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 79 ◽  
Author(s):  
Chumisa C. Dweba ◽  
Oliver T. Zishiri ◽  
Mohamed E. El Zowalaty
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Staphylococcus Aureus ◽  
South African ◽  
Resistance Genes ◽  
Heavy Metal Resistance ◽  
Livestock Production ◽  
Metal Resistance ◽  
Diffusion Method ◽  
Methicillin Resistant

Staphylococcus aureus is one of the most important pathogens of humans and animals. Livestock production contributes a significant proportion to the South African Gross Domestic Product. Consequently, the aim of this study was to determine for the first time the prevalence, virulence, antibiotic and heavy metal resistance in livestock-associated S. aureus isolated from South African livestock production systems. Microbial phenotypic methods were used to detect the presence of antibiotic and heavy metal resistance. Furthermore, molecular DNA based methods were used to genetically determine virulence as well as antibiotic and heavy metal resistance determinants. Polymerase chain reaction (PCR) confirmed 217 out of 403 (53.8%) isolates to be S. aureus. Kirby-Bauer disc diffusion method was conducted to evaluate antibiotic resistance and 90.8% of S. aureus isolates were found to be resistant to at least three antibiotics, and therefore, classified as multidrug resistant. Of the antibiotics tested, 98% of the isolates demonstrated resistance towards penicillin G. High resistance was shown against different heavy metals, with 90% (196/217), 88% (192/217), 86% (188/217) and 84% (183/217) of the isolates resistant to 1500 µg/mL concentration of Cadmium (Cd), Zinc (Zn), Lead (Pb) and Copper (Cu) respectively. A total of 10 antimicrobial resistance and virulence genetic determinants were screened for all livestock associated S. aureus isolates. Methicillin-resistant S. aureus (MRSA) isolates were identified, by the presence of mecC, in 27% of the isolates with a significant relationship (p < 0.001)) with the host animal. This is the first report of mecC positive LA-MRSA in South Africa and the African continent. The gene for tetracycline resistance (tetK) was the most frequently detected of the screened genes with an overall prevalence of 35% and the highest prevalence percentage was observed for goats (56.76%) followed by avian species (chicken, duck and wild birds) (42.5%). Virulence-associated genes were observed across all animal host species. The study reports the presence of luks/pv, a gene encoding the PVL toxin previously described to be a marker for community acquired-MRSA, suggesting the crossing of species between human and livestock. The high prevalence of S. aureus from the livestock indicates a major food security and healthcare threat. This threat is further compounded by the virulence of the pathogen, which causes numerous clinical manifestations. The phenomenon of co-selection is observed in this study as isolates exhibited resistance to both antibiotics and heavy metals. Further, all the screened antibiotic and heavy metal resistance genes did not correspond with the phenotypic resistance.

Heavy Metal Content in Feedstuffs and Feeds in Hubei Province, China

2020 ◽  
Vol 83 (5) ◽  
pp. 762-766
Author(s):  
CAN TAO ◽  
XIAOTIAN WEI ◽  
BEIYU ZHANG ◽  
MAN ZHAO ◽  
SHUAI WANG ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Heavy Metal Contamination ◽  
Absorption Spectrometry ◽  
Hubei Province ◽  
Incidence Rates ◽  
Metal Exposure ◽  
Atomic Fluorescence Spectrometry ◽  
Republic Of China ◽  
Feed Management

ABSTRACT Heavy metal pollution threatens the health and life of animals and humans through the food chain. This study was performed to survey the heavy metal contamination in feedstuffs and feeds in Hubei Province, People's Republic of China, from 2012 to 2016. Samples were analyzed for cadmium (306 samples), mercury (117 samples), chromium (149 samples), and arsenic (4,358 samples) using atomic absorption spectrometry or atomic fluorescence spectrometry. The incidence rates of cadmium, mercury, chromium, and arsenic contamination of feedstuffs and feeds were high, and feeds were most often contaminated with chromium, followed by arsenic, cadmium, and mercury. The concentrations of heavy metals in samples positive for cadmium, mercury, chromium, and arsenic ranged from 0.001 to 1.200, 0.002 to 6.540, 0.060 to 8737.000, and 0.070 to 33.000 mg/kg, respectively. The mineral and additive samples had higher concentrations of heavy metals. The present study findings highlight the importance of monitoring heavy metals in feedstuffs and feeds and implementing feed management and bioremediation strategies to reduce heavy metal exposure. HIGHLIGHTS

scholarly journals Microbial bioremediation of heavy metals

2021 ◽  
Vol 75 (2) ◽  
pp. 103-115
Author(s):  
Ana Volaric ◽  
Zorica Svircev ◽  
Dragana Tamindzija ◽  
Dragan Radnovic
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Heavy Metal Resistance ◽  
Pilot Scale ◽  
Resistance Mechanisms ◽  
Metal Resistance ◽  
Novel Technologies ◽  
Living Organisms ◽  
Microbial Bioremediation ◽  
Physical And Chemical

Heavy metal pollution is one of the most serious environmental problems, due to metal ions persistence, bioavailability, and toxicity. There are many conventional physical and chemical techniques traditionally used for environmental clean-up. Due to several drawbacks regarding these methods, the use of living organisms, or bioremediation, is becoming more prevalent. Biotechnological application of microorganisms is already successfully implemented and is in constant development, with many microbial strains successfully removing heavy metals. This paper provides an overview of the main heavy metal characteristics and describes the interactions with microorganisms. Key heavy metal resistance mechanisms in microorganisms are described, as well as the main principles and types of heavy metal bioremediation methods, with details on successful pilot scale bioreactor studies. Special attention should be given to indigenous bacteria isolated from the polluted environments since such species are already adapted to contamination and possess resistance mechanisms. Utilization of bacterial biofilms or consortia could be advantageous due to higher resistance and a combination of several metabolic pathways, and thus, the possibility to remove several heavy metals simultaneously. Novel technologies covered in this review, such as nanotechnology, genetic engineering, and metagenomics, are being introduced to the field of bioremediation in order to improve the process. To conclude, bioremediation is a potentially powerful solution for cleaning the environment.

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