S1 Site Research Articles

The inhibitory effect of vitamin D on myocardial homocysteine levels involves activation of Nrf2-mediated methionine synthase

BackgroundHomocysteine (Hcy) is a synthetic amino acid containing sulfhydryl group, which is an intermediate product of the deep metabolic pathway of methionine and cysteine. The abnormal increase in fasting plasma total Hcy concentration caused by various factors is called hyperhomocysteine (HHcy). HHcy is closely relevant to the occurrence and progression of diverse cardiovascular and cerebrovascular diseases, such as coronary heart disease, hypertension and diabetes, etc. Vitamin D/vitamin D receptor (VDR) pathway is pointed out that prevent cardiovascular disease by reducing serum homocysteine levels. Our research is designed to explore the potential mechanism of vitamin D in the prevention and treatment of HHcy. Methods and resultsThe Hcy and 25(OH)D3 levels in mouse myocardial tissue, serum or myocardial cells were detected using ELISA kits. The expression levels of VDR, Nrf2 and methionine synthase (MTR) were observed using Western blotting, immunohistochemistry and real time polymerase chain reaction (PCR). General information of the mice, including diet, water intake and body weight, was recorded. Vitamin D up-regulated the mRNA and protein expression of Nrf2 and MTR in mouse myocardial tissue and cells. CHIP assay determined that the combination of Nrf2 binding to the S1 site of the MTR promoter in cardiomyocytes using traditional PCR and real time PCR. Dual Luciferase Assay was applied to detect the transcriptional control of Nrf2 on MTR. The up-regulation effect of Nrf2 on MTR was verified by Nrf2 knockout and overexpression in cardiomyocytes. The role of Nrf2 in vitamin D inhibition of Hcy was revealed using Nrf2-knockdown HL-1 cells and Nrf2 heterozygous mice. Western blotting, real time PCR, IHC staining and ELISA showed that Nrf2 deficiency could restrain the increase in MTR expression and the decrease in Hcy level induced by vitamin D. The transcriptional activities of Nrf2/MTR were activated by vitamin D/VDR with a decrease in Hcy. ConclusionVitamin D/VDR upregulates MTR in an Nrf2-dependent manner, thereby reducing the risk of HHcy.

A Critical Study on Acylating and Covalent Reversible Fragment Inhibitors of SARS-CoV-2 Main Protease Targeting the S1 Site with Pyridine.

SARS coronavirus main proteases (3CL proteases) have been validated as pharmacological targets for the treatment of coronavirus infections. Current inhibitors of SARS main protease, including the clinically admitted drug nirmatrelvir are peptidomimetics with the downsides of this class of drugs including limited oral bioavailability, cellular permeability, and rapid metabolic degradation. Here, we investigate covalent fragment inhibitors of SARS Mpro as potential alternatives to peptidomimetic inhibitors in use today. Starting from inhibitors acylating the enzyme's active site, a set of reactive fragments was synthesized, and the inhibitory potency was correlated with the chemical stability of the inhibitors and the kinetic stability of the covalent enzyme-inhibitor complex. We found that all tested acylating carboxylates, several of them published prominently, were hydrolyzed in assay buffer and the inhibitory acyl-enzyme complexes were rapidly degraded leading to the irreversible inactivation of these drugs. Acylating carbonates were found to be more stable than acylating carboxylates, however, were inactive in infected cells. Finally, reversibly covalent fragments were investigated as chemically stable SARS CoV-2 inhibitors. Best was a pyridine-aldehyde fragment with an IC50 of 1.8 μM at a molecular weight of 211 g/mol, showing that pyridine fragments indeed are able to block the active site of SARS-CoV-2 main protease.

Overview of the structure and function of the dopamine transporter and its protein interactions.

The dopamine transporter (DAT) plays an integral role in dopamine neurotransmission through the clearance of dopamine from the extracellular space. Dysregulation of DAT is central to the pathophysiology of numerous neuropsychiatric disorders and as such is an attractive therapeutic target. DAT belongs to the solute carrier family 6 (SLC6) class of Na+/Cl- dependent transporters that move various cargo into neurons against their concentration gradient. This review focuses on DAT (SCL6A3 protein) while extending the narrative to the closely related transporters for serotonin and norepinephrine where needed for comparison or functional relevance. Cloning and site-directed mutagenesis experiments provided early structural knowledge of DAT but our contemporary understanding was achieved through a combination of crystallization of the related bacterial transporter LeuT, homology modeling, and subsequently the crystallization of drosophila DAT. These seminal findings enabled a better understanding of the conformational states involved in the transport of substrate, subsequently aiding state-specific drug design. Post-translational modifications to DAT such as phosphorylation, palmitoylation, ubiquitination also influence the plasma membrane localization and kinetics. Substrates and drugs can interact with multiple sites within DAT including the primary S1 and S2 sites involved in dopamine binding and novel allosteric sites. Major research has centered around the question what determines the substrate and inhibitor selectivity of DAT in comparison to serotonin and norepinephrine transporters. DAT has been implicated in many neurological disorders and may play a role in the pathology of HIV and Parkinson's disease via direct physical interaction with HIV-1 Tat and α-synuclein proteins respectively.

3D-QSAR, in vitro assay and MD simulations studies on the design, bioactivities and different inhibitory modes of the novel DPP-IV inhibitory peptides

3D-QSAR, in vitro assay and molecular dynamic simulations were adopted to investigate the DPP-IV inhibitory peptides and its molecular mechanism. A CoMFA model (Q2=0.837, R2=0.991) and a CoMSIA model (Q2=0.726, R2=0.990) of DPP-IV inhibitory peptides were established. Six novel peptides were designed by the 3D-QSAR models. In vitro assay demonstrated that the activities of the six novel peptides were higher than that of most DPP-IV inhibitory peptides. Interestingly, different mechanisms of the competitive and non-competitive inhibitory peptides were suggested by molecular docking and molecular dynamics simulations. Trp-of WPV bound to the S1 site destroyed the structure of DPP-IV and blocked the side opening to the active site for the non-competitive peptide. This prevented the substrates from entering the active pocket and reduced the activity of DPP-IV. Residues Ser630, Glu205 and Glu206 were the key residues for competitive inhibitors to inhibit DPP-IV. The binding sites and modes of competitive inhibitory peptides were the same as the substrates.

Based on the Results of PEDV Phylogenetic Analysis of the Most Recent Isolates in China, the Occurrence of Further Mutations in the Antigenic Site S1° and COE of the S Protein Which Is the Target Protein of the Vaccine

The continuous challenge of existing vaccine systems by porcine epidemic diarrhea virus (PEDV) variant strains in recent years, it caused significant economic losses in the global swine industry. A PEDV virulent strain CH/HLJBQL/2022 was successfully isolated in China in this study. A genome-wide based phylogenetic analysis suggests that CH/HLJBQL/2022 belongs to the GII subtype, and 96.3%–99.6% homology existed in the whole genomes of other strains. For the first time, simultaneous mutations of four amino acids were found in the highly conserved membrane (M) and nucleocapsid (N) proteins, as well as five amino acid mutations that differed from the vast majority of strains in the spike (S) protein. Mutations in the M and S proteins were found to produce coils with different angles by building 2D and 3D structural models. Epitope analysis indicated that the isolates produced specific changes and that the transmembrane function of the M protein had not been affected. In addition, typing markers exist during strain evolution, but isolates are using the fusion of specific amino acids from multiple variant strains to add additional features, as also demonstrated by protein alignments and 3D models of numerous subtype strains. These results suggest that aa mutations in the M and S proteins may have changed the structure and antigenic epitope of the isolates and PEDV is evolving again on the basis of variants that have been found to counteract the immune network of the new vaccine.

An Investigation on Soil Amplification through Site Factors Used in Seismic Design Codes

This article aims to investigate the site amplification through site coefficients given in the seismic codes. A set of 84 ground motion records in a base rock form and targeted to have different frequency contents was formed. The surface forms of these records altered by 100 different soil conditions were determined. Using this set of 8400 ground motion records, site amplification phenomenon is examined. After a PGA of 0.3 g, ground motions have similar behaviour in terms of short period amplification. Numerical figures as average and with a safety level of 84% for the SS and S1 site coefficients were given and compared with the code which are observed to be unconservative for stiff soils and too conservative for soft soils. Linking SS with a V S value of 600 m/s and S1 with a V S value of 120 m/s seems to be useful to understand some amplification behaviours. The variability of ZB and ZC site classes for short period site coefficient and ZE and ZD site classes for midperiod site coefficient seems to be greater when compared to others.

Structural heterogeneity of single-atom catalysts and true active site generation via ligand exchange during electrochemical H2O2 production

Although often overlooked, single-atom catalysts inevitably contain heterogeneous active sites and their structures can further change under reaction conditions. Here, we conduct rigorous in situ X-ray absorption spectroscopy with 1–10 wt% Pt on S-doped zeolite-templated carbon (SZTC) to elucidate their remarkable electrocatalytic H2O2 synthesis properties. SZTC with a curved polyaromatic framework and abundant sulfur functional groups can stabilize isolated Pt sites with up to 10 wt% Pt loading. Although all catalysts contain apparently identical Pt–S4 sites in their as-synthesized form, the Pt-specific activity increases rapidly with increasing Pt loading. It appears that Pt first forms inert Pt–S4 in SZTC and then forms labile Pt–S4 with increasing Pt loading. Upon contact with aqueous electrolytes, only the labile sites are converted to true active sites, Pt–S2(H2O)2, via ligand exchange with H2O. The results provide invaluable insights for understanding the heterogeneity and dynamic structural changes of single-atom catalysts.

Structural bases for blockade and activation of BK channels by Ba2+ ions.

Calcium ions increase the open probability of the large conductance potassium (BK) channels by binding to high affinity sites within the large cytosolic Ca2+ sensing structure called the gating ring. This Ca2+ sensing structure is formed by eight Regulator of K+ Conductance (RCK) domains, two from each subunit of the channel, termed RCK1 and RCK2. Other divalent species, like Ba2+ ions, are also able to activate BK channels by interacting with the Ca2+ sensor. Unlike Ca2+ that activate BK channel through all RCK domains, Ba2+ does it selectively through the RCK2 domain. In addition to activation, Ba2+ can also block K+ permeation by binding to the selectivity filter of BK channels. Here we present and discuss Cryo-EM structures of BK channels with Ba2+. Structurally, blockade arises from one Ba2+ occupying the traditional K+ site S3 in the selectivity filter of the channel. In addition, electronic densities attributed to K+ ions are detected at K+ sites S2 and S4. In the gating ring, eight Ba2+ ions are bound to the corresponding high affinity Ca2+ binding sites. Thereby, the lack of functional significance of the RCK1 on the activation by Ba2+ should arise because the architectures of the gating rings in our structures represent intermediate transitions between the close and the open configurations. Finally, these Ba2+ structures reveal an intricate series of concerted changes of the RCK 1 and RCK2 from the same subunit, suggesting coordinated intra-subunit dynamics.

Mechanism of K+ transport along the intersubunit tunnel of kdpFABC.

Prokaryotes such as E. coli employ a unique channel-pump protein complex called kdpFABC to import K+ into the cell in low external K+ environments. KdpA is an ion channel subunit and kdpB is a P-type ATPase. Current research indicates that transport of K+ ions occur by diffusion of K+ ions from the kdpA ion-binding site to the kdpB ion-binding site through a ∼40 Å long tunnel that passes through the channel-pump interface. However, there is no clear consensus on whether K+ ions or water molecules populate the tunnel in the cryo-EM studies. Through molecular dynamics simulations, we find that K+ ions and water molecules co-exist in the tunnel. Furthermore, we notice that not more than two K+ ions can coexist in the tunnel after the S3 site of the selectivity filter and before the channel-pump interface. We employ well-tempered metadynamics simulations to calculate the free energy of ion transport along the intramembrane tunnel, and preliminary data show that a large barrier prevents spontaneous diffusion of a K+ ion from the channel to the pump subunit in the E1-ATP state. Further investigations are ongoing.

Determination of pollution status of Nilüfer river by water and bottom sediment analysis

Abstract This study aims to evaluate the Nilüfer river in terms of water quality standards. Bottom sediment and water samples were taken from six different locations. The analysis of the physicochemical parameters of water compared with FAO for irrigation water quality standards. In addition, the SAR (sodium adsorption ratio), % Na, MAR (magnesium adsorption ratio), RSC (residual sodium carbonate), KR (Kelley's ratio) and % PI (permeability index) parameters were evaluated in water samples. The bottom sediment pollution situation was evaluated in terms of pollution index such as TEC (threshold effect concentration) and PEC (probable effect concentration). According to the results of the study, the irrigation water classes of the samples were determined as C2S1 and C3S1. Especially, sample sites S4, S5 and S6 were not suitable for irrigation in terms of RSC, KR. The bottom sediment exceeded the TEC and PEC limit values in terms of Zn, Cu, Cr and Ni contents. This may cause adverse effects on the majority of sediment-dwelling organisms.The use of alternative water sources should be preferred. The river can be used for irrigation with precaution but extensive treatment is required before use for irrigation purposes to prevent adverse public health effects.

Heavy metals and trace elements contamination risks in peri-urban agricultural soils in Nairobi city catchment, Kenya

IntroductionWith urbanization and industrialization in the developing world, urban and peri-urban agriculture is increasingly contributing to urban food systems, employment, and income generation opportunities. However, urbanization and industrialization may release harmful pollutants, including heavy metals and trace elements into agricultural soils, posing ecological, environmental and public health concerns. This paper assessed the potential risks of soil contamination with heavy metals and trace elements in peri-urban farmlands in Nairobi city catchment in Kenya. MethodsA total of 60 soil samples were collected from ten vegetable farming zones (S1-S10) and processed following standard protocols. The concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn were analyzed in the samples using inductively coupled plasma-mass spectrometry (ICP-MS). Results and discussionResults revealed that the soil samples have elevated concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn, with some elements including As (1.7%), Cd (13.3%), Mn (80%), Pb (1.7%) and Zn (11.7%) exceeding the permissible thresholds for agricultural soils. The spatial distribution of the elements exhibited three similar distribution patterns with slight variations between the hotspot sites of the different elements: (i) Co and Mn, (ii) Cu and Cr and (iii) As, Cd, Fe, Hg, Pb and Zn, while Ni and V exhibited singular spatial distributions compared to other elements. Elements such as As, Cd, Co, Fe, Hg, Mn, Pb and Zn appeared to be of anthropogenic enrichment, while Cr, Cu, Ni and V appeared to originate mainly from lithogenic and natural sources. The elements As, Cd, Hg and Pb exhibited high ecological risks, with Cd contributing about 46-66% of the overall ecological risk. The sampling sites S1, S5, S7, S9 and S10 depicted the highest ecological risks of 145, 103, 146, 121 and 146, respectively. The findings call for proper zoning of suitable agricultural areas and sound waste management protocols in urban and peri-urban landscapes. Further, remediation of contaminated soils and farmers’ sensitization are recommended for ecological and public health risk alleviation.

Heavy metal contamination in soil and groundwater around industrial areas of Kollam District, Kerala, India.

The present study was intended for assessing the contamination level of various heavy metals in surface soil and groundwater around the automobile workshops situated at different locations in the Kollam District of Kerala state, India. The procured soil and groundwater samples were analyzed for cadmium, zinc, iron, lead, nickel, chromium, copper, manganese, and arsenic using atomic absorption spectrophotometer by following standard procedures. The contamination level of these metals was assessed using the pollution indices like enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). The results revealed that the concentrations of all analyzed metals in the surface soils of the automobile workshops were higher than the control. On the contrary, the concentration of no heavy metal in the groundwater was either equal to or higher than the limit prescribed by WHO. However, the concentration levels of Fe, Pb, Cu, and Zn were either equal to or higher than the control values. Based on the Igeo, CF, and EF, it was found that the contamination intensity of the heavy metals in soil decreased in the following order: Fe > Pb > Cd > As > Cr > Zn > Cu > Ni > Mn. From the results of PLI, it was interpreted that the sampling sites S2, S4, and S5 were highly polluted. Non-contamination of underground water from the age-old workshops is the uniqueness of the present study against the other studies, which were completed in alluvial formations with inverse results. In the studied region, the groundwater is stored in the hard rock formations and its hydraulics remains different from alluvial aquifers.

Receptor binding motif surrounding sites in the spike 1 protein of infectious bronchitis virus have high susceptibility to mutation related to selective pressure.

To date, various genotypes of infectious bronchitis virus (IBV) have co-circulated and in Korea, GI-15 and GI-19 lineages were prevailing. The spike protein, particularly S1 subunit, is responsible for receptor binding, contains hypervariable regions and is also responsible for the emerging of novel variants. This study aims to investigate the putative major amino acid substitutions for the variants in GI-19. The S1 sequence data of IBV isolated from 1986 to 2021 in Korea (n = 188) were analyzed. Sequence alignments were carried out using Multiple alignment using Fast Fourier Transform of Geneious prime. The phylogenetic tree was generated using MEGA-11 (ver. 11.0.10) and Bayesian analysis was performed by BEAST v1.10.4. Selective pressure was analyzed via online server Datamonkey. Highlights and visualization of putative critical amino acid were conducted by using PyMol software (version 2.3). Most (93.5%) belonged to the GI-19 lineage in Korea, and the GI-19 lineage was further divided into seven subgroups: KM91-like (Clade A and B), K40/09-like, QX-like (I-IV). Positive selection was identified at nine and six residues in S1 for KM91-like and QX-like IBVs, respectively. In addition, several positive selection sites of S1-NTD were indicated to have mutations at common locations even when new clades were generated. They were all located on the lateral surface of the quaternary structure of the S1 subunits in close proximity to the receptor-binding motif (RBM), putative RBM motif and neutralizing antigenic sites in S1. Our results suggest RBM surrounding sites in the S1 subunit of IBV are highly susceptible to mutation by selective pressure during evolution.

Multivariate studies and heavy metal pollution in soil from gold mining area

Mining generates large volumes of waste, which if not regulated can release toxic metals, causing widespread environmental contamination. This study focused on heavy metal contamination in topsoil within a mining area at Nangodi in the Northern Region of Ghana. A total of 24 soil samples were collected from the study area and control samples were analyzed for Hg, Pb, Cd, As, Cr, and Fe using atomic absorption spectroscopy. Results of Pollution Index estimations and Geo-accumulation index (Igeo) classified the soil samples as moderately contaminated to heavily contaminated. Soil samples were severely enriched with As and moderately enriched with b, and Hg. Multivariate analyses such as factor analysis and cluster analysis were employed to examine the relationship between the metals and also differentiate the influence of the natural background content of metals from that due to human activities. Factor analysis identified three polluted soil factor associations. Cadmium, Fe, As, and Pb associated with factor 1, were due to anthropogenic activities. The high intercorrelation revealed by As and Pb shows similarity in their sources. Factor two dominated by Hg is considered an anthropogenic component. Factor 3 correlated with Cr and can be considered a natural component. Correlation analysis and cluster analysis supported each other. Results from the bi-plots showed that sites S1, S8, S11, and S18, have similar metal composition as the control site. Heavy metal contents in soils sampled from Zones A and B have been influenced by the mining activities as seen from the associations of these sites in the bi-plots. The results are useful for metal source identification, and can contribute to monitoring and regulatory programs.

Enhancing photocatalytic overall water-splitting performance on dual-active-sites of the Co-P@MoS2 catalysts: a DFT study.

The rational construction of photocatalysts possesses tremendous potential to solve the energy crisis and environmental pollution; however, designing a catalyst for solar-driven overall water-splitting remains a great challenge. Herein, we propose a new MoS2-based photocatalyst (Co-P@MoS2), which skillfully uses the cobalt (Co) atom to stimulate in-plane S atoms and employs the phosphorus (P) atom to stabilize the basal plane by forming the Co-P bands. Using density functional theory (DFT), it was found that oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) can occur at the P site and S2 site of the Co-P@MoS2, respectively, and the dual-active sites successfully makes a delicate balance between the adsorption and dissociation of hydrogen. Furthermore, the improved overall water-splitting performance of Co-P@MoS2 was verified by analyzing the results of the electron structure and the dynamics of photogenerated carries. It was found that the imbalance of electron transfer caused by the introduction of the Co atom was the main contributor to the catalytic activity of Co-P@MoS2. Our study broadens the idea of developing photocatalysts for the overall water-splitting.

APPLICATION OF MULTIPLE LINEAR REGRESSION MODELS TO DETERMINE MICROBIAL WATER QUALITY CHANGES ACROSS HIGHLY DISTURBED LOWER HIMALAYAN STREAM AND THE GROUNDWATER SOURCES IN THE PROXIMITY, JAMMU (INDIA)

The study investigated the microbial quality of Behlol stream- a Lower Himalayan stream and groundwater sources in its proximity areas in terms of MPN index/100 ml for total and faecal coliforms and application of statistical tools like correlation and linear regression to deduce beneficial parametric associations for easy interpretation of the data. MPN/100 ml index analysis revealed severe microbial contamination at the surface water sampling site S2 and the nearby groundwater sites G2 and G3 indicating the impact of surface water pollution on the groundwater sources. The authors observed that the rate of groundwater contamination decreased with the increase in distance from the surface water sites suggesting that the groundwater pollution is mainly contributed by the release of combined industrial and sewage wastes into the Behlol stream. The study also identified bacterial genera like Escherichia, Enterobacter, Klebsiella, Citrobacter, Proteus, Salmonella, and Shigella, belonging to the family Enterobacteriaceae via colony cultural characteristics and biochemical tests. A significant relationship obtained from an orderly linear correlation and regression in this study provides a better alternative for a systematic study over the conventional techniques; reducing the quantum of analysis and can therefore be treated as a rapid method for water quality monitoring

Probing ion binding in the selectivity filter of the Cav1.1 channel with molecular dynamics

Cav1.1 is the voltage-gated calcium channel essential for the contraction of skeletal muscles upon membrane potential changes. Structural determination of the Cav1.1 channel opens the avenue toward understanding of the structure-function relationship of voltage-gated calcium channels. Here, we show that there exist two Ca2+-binding sites, termed S1 and S2, within the selectivity filter of Cav1.1 through extensive molecular dynamics simulations on various initial ion arrangement configurations. The formation of both binding sites is associated with the four Glu residues (Glu292/614/1014/1323) that constitute the so-called EEEE locus. At the S1 site near the extracellular side, the Ca2+ ion is coordinated with the negatively charged carboxylic groups of these Glu residues and of the Asp615 residue either in a direct way or via an intermediate water molecule. At the S2 site, Ca2+ binding shows two distinct states: an upper state involving two out of the four Glu residues in the EEEE locus and a lower state involving only one Glu residue. In addition, there exist two recruitment sites for Ca2+ above the entrance of the filter. These findings promote the understanding of mechanism for ion permeation and selectivity in calcium channels.

Regulation of Ion Permeation of the KcsA Channel by Applied Midinfrared Field.

Ion transport molecules are involved in many physiological and pathological processes and are considered potential targets for cancer treatment. In the large family of ion transport molecules, potassium (K) ion channels, as surface-expressed proteins, show the highest variability and most frequent expression changes in many tumor types. The key to exploring the permeation of K+ through potassium channels lies in the conserved sequence TVGYG, which is common in the selectivity filter (SF) region of all potassium channels. We found that the K+ flux significantly increased with the help of a specific frequency terahertz electromagnetic wave (51.87 THz) in the KcsA channel using a molecular dynamics combined model through the combined simulation of the constant electric field method and ion imbalance method. This frequency has the strongest absorption peak in the infrared spectrum of -C=O groups in the SF region. With the applied electric field of 51.87 THz, the Y78 residue at the S1 site of the SF has a smaller vibration amplitude and a more stable structure, which enables the K+ to bind closely with the carbonyl oxygen atoms in the SF and realize ion conduction in a more efficient direct Coulomb knock-on.

A biochemical and lipidomic approach to perceive Halimione portulacoides (L.) response to mercury: An environmental perspective

The impact of hazardous materials, such as Hg, on life is far from being understood and due to the high number of polluted sites it has generated great concern. A biochemical and lipidomic approach was used to assess the effects of Hg on the saltmarsh halophyte Halimione portulacoides. Plants were collected at two sites of a Hg contaminated saltmarsh. Hg accumulation and distribution in the plant, biochemical parameters (antioxidant and metabolic) and lipid profiles were determined and compared between plant organs and sites (s1 and s2). Hg did not induce antioxidant enzyme activity. Lipid profiles changed under Hg exposure, especially in leaves, decreasing the unsaturation level, the membrane fluidity and stability, and evidencing that membrane lipid remodeling influences plant tolerance to Hg. This knowledge can help select the most appropriate methodologies for the restoration of Hg polluted hotspots, curtailing a serious environmental problem threatening saltmarshes.

Utjecaj urbanih oblika na varijacije urbanih toplinskih otoka u mediteranskim gradovima

The Urban Heat Island (UHI) effect has increased with the increase in urbanisation and climate change, especially in cities with arid climates. This study aims to understand the influence of urban forms on creating UHIs by assessing seven sites in a case study in Mostaganem city, which is located on the Mediterranean coast in northern Algeria. A weather station and an infrared thermometer were used to collect the thermal data from the selected sites (S1 to S7). Site S1 was modelled and simulated using ENVI-met software to evaluate the UHI effect on the open area bounded by the surrounding buildings. The simulation data was then validated by the real time data collected from the actual site. Thereafter, seven common urban form configurations were identified and modelled around the same site (S1), and simulated for their individual impacts, one by one. The simulation results were compared in terms of air temperature, wind speed, and ground surface temperature, not to mention that the influence of the different urban forms contributed to the UHI effect in the bounded area. Semi-enclosed configurations of the urban forms that were protected from direct solar radiation recorded the lowest air and ground temperatures, while the difference between temperatures on the site rose to 2 °C in the hottest hours of the day.