The Effects of Heavy Metal Pollution on Soil Nitrogen Transformation and Rice Volatile Organic Compounds under Different Water Management Practices.

One of the most concerning global environmental issues is the pollution of agricultural soils by heavy metals (HMs), especially cadmium, which not only affects human health through Cd-containing foods but also impacts the quality of rice. The soil's nitrification and denitrification processes, coupled with the release of volatile organic compounds by plants, raise substantial concerns. In this review, we summarize the recent literature related to the deleterious effects of Cd on both soil processes related to the N cycle and rice quality, particularly aroma, in different water management practices. Under both continuous flooding (CF) and alternate wetting and drying (AWD) conditions, cadmium has been observed to reduce both the nitrification and denitrification processes. The adverse effects are more pronounced in alternate wetting and drying (AWD) as compared to continuous flooding (CF). Similarly, the alteration in rice aroma is more significant in AWD than in CF. The precise modulation of volatile organic compounds (VOCs) by Cd remains unclear based on the available literature. Nevertheless, HM accumulation is higher in AWD conditions compared to CF, leading to a detrimental impact on volatile organic compounds (VOCs). The literature concludes that AWD practices should be avoided in Cd-contaminated fields to decrease accumulation and maintain the quality of the rice. In the future, rhizospheric engineering and plant biotechnology can be used to decrease the transport of HMs from the soil to the plant's edible parts.

Response to carvacrol monoterpene in the emergence of Allium cepa L. seeds exposed to salt stress.

Abiotic stresses including sodium chloride (NaCl) are known to negatively affect plant physiology and seed germination by inducing a delay in establishing seedling emergence. The monoterpene carvacrol is the major component of several aromatic plants and seems to interfere with germination and seedling growth. In this study, we investigated whether treatment with carvacrol attenuates the effects of NaCl on the germination and development of Allium cepa, where biochemical parameters were also analyzed. The results showed that the Emergency Speed Index (ESI) was near to 2.0 in the control group. The groups NaCl, carvacrol alone, and in co-treatment with NaCl exhibited an ESI below 0.8, being significantly smaller when compared to the control. NaCl + carvacrol significantly inhibited seed emergence in relation to the NaCl group. Only the content of malondialdehyde was significantly altered by NaCl.

Designing and Exploration of the Biological Potentials of Novel Centrosymmetric Heteroleptic Copper(II) Carboxylates.

Copper(II) complexes with a general formula [Cu2(3,4-F2C6H3CH2COO)4(L)2], where L = 2-methylpyridine (1) and 3-methylpyridine (2), are reported here. The FTIR spectra of the complexes confirmed the bridging bidentate coordination mode of the carboxylate ligand. The low (475 and 449 cm-1) and strong (727 & 725 cm-1) intensity bands in the FTIR spectra, due to Cu-N stretches and pyridyl ring vibrations, confirmed coordination of the 2-/3-methyl pyridine co-ligands in complexes 1 and 2, respectively. A binuclear paddlewheel structural arrangement with a square pyramidal geometry was confirmed for copper atoms in the complexes via single-crystal X-ray analysis. The DPPH, •OH radical, and α-amylase enzyme inhibition assays showed higher activities for the complexes than for the free ligand acid. The binding constant (Kb = 1.32 × 105 for 1 and 5.33 × 105 for 2) calculated via UV-VIS absorption measurements and docking scores (-6.59 for 1 and -7.43 for 2) calculated via molecular docking showed higher SS-DNA binding potential for 2 compared to 1. Viscosity measurement also reflected higher DNA binding ability for 2 than 1. Both complexes 1 and 2 (docking scores of -7.43 and -6.95, respectively) were found to be more active inhibitors than the free ligand acid (docking score of -5.5159) against the target α-amylase protein. This in silico study has shown that the herein reported compounds follow the rules of drug-likeness and exhibit good potential for bioavailability.

Synthesis, Antioxidant, Molecular Docking and DNA Interaction Studies of Metal-Based Imine Derivatives.

Currently, numerous ongoing studies are investigating the interaction of free radicals with biological systems, such as lipids, DNA and protein. In the present work, synthesis, characterization, antioxidant, DNA binding and molecular docking studies of Schiff base ligand and its Ni(II), Co(II), Cu(II) and Zn(II) were evaluated. The metal complexes have shown significant dose-dependent antioxidant activities higher than those of the free ligand but lesser than those of the standard antioxidant, ascorbic acid. The DNA binding constants (Kb) were found in the order Zn(pimp)2 {9.118 × 105 M-1} > H-pimp {3.487 × 105 M-1} > Co(pimp)2 {3.090 × 105 M-1} > Ni(pimp)2 {1.858 × 105 M-1} > Cu(pimp)2 {1.367 × 105 M-1}. Binding constants (Kb) values calculated from the molecular docking analysis were found to be in close agreement with the experimental results. The obtained results indicate the importance of synthesis complexes as a source of synthetic antioxidants and anticancer drugs.

Syntheses and structural characterization of divalent metal complexes (Co, Ni, Pd and Zn) of sterically hindered thiourea ligand and a theoretical insight of their interaction with SARS-CoV-2 enzyme.

Reacting two equivalents of sterically hindered 1,3-bis(2,6-diethylphenyl)thiourea ligand (L) with CoCl2, NiBr2, PdX2 (X = Cl; Br) and ZnI2 in acetonitrile afforded the corresponding bulky thiourea ligand stabilized four coordinated monomeric [L2CoCl2] (1), [L2NiBr2] (2), [L2PdX2] (3a: X = Cl; 3b: X = Br) and [L2ZnI2] (4.2CH3CN) complexes. Compound 1, 2 and 4.2CH3CN are tetrahedral whereas Pd complexes (3a and 3b) are square planar. In solution, palladium complexes are dominated by cis-isomers. Structural characterization shows inter- and intramolecular hydrogen bonding. Hirshfeld surface and fingerprint plots indicated significant intermolecular interactions in the crystal network. Molecular docking analysis revealed relatively higher SARS-CoV-2 enzyme interacting abilities of the synthesized complexes compared to the free ligand. All compounds have been characterized by elemental analyses, NMR spectroscopy and single-crystal X-ray diffraction.

Water-Soluble Carbon Monoxide-Releasing Molecules (CORMs).

Carbon monoxide-releasing molecules (CORMs) are promising candidates for producing carbon monoxide in the mammalian body for therapeutic purposes. At higher concentrations, CO has a harmful effect on the mammalian organism. However, lower doses at a controlled rate can provide cellular signaling for mandatory pharmacokinetic and pathological activities. To date, exploring the therapeutic implications of CO dose as a prodrug has attracted much attention due to its therapeutic significance. There are two different methods of CO insertion, i.e., indirect and direct exogenous insertion. Indirect exogenous insertion of CO suggests an advantage of reduced toxicity over direct exogenous insertion. For indirect exogenous insertion, researchers are facing the issue of tissue selectivity. To solve this issue, developers have considered the newly produced CORMs. Herein, metal carbonyl complexes (MCCs) are covalently linked with CO molecules to produce different CORMs such as CORM-1, CORM-2, and CORM-3, etc. All these CORMs required exogenous CO insertion to achieve the therapeutic targets at the optimized rate under peculiar conditions or/and triggering. Meanwhile, the metal residue was generated from i-CORMs, which can propagate toxicity. Herein, we explain CO administration, water-soluble CORMs, tissue accumulation, and cytotoxicity of depleted CORMs and the kinetic profile of CO release.

Primary percutaneous coronary intervention in CAD patients: A comparison of major adverse cardiovascular events of second- and third-generation drug-eluting stents.

Background: Biodegradable polymer (BP) drug-eluting stents (DES) have been introduced as a novel solution to the problems of durable polymer (DP) stents. In Pakistan, very few studies are available for the treatment intervention in post-primary percutaneous coronary intervention (PPCI) patients. Our study will compare the major adverse cardiovascular events (MACEs) and their predictors in patients with coronary artery disease (CAD) undergoing PPCI with second- or third-generation DES. Methodology: An observational, retrospective, cohort study was carried out on CAD patients undergoing PPCI with either second- (DP-XIENCE Prime/XIENCE Xpedition) or third-generation (BP-BioMatrix NeoFlex/BioMatrix Alpha) DES. MACEs were assessed after 1 year of PPCI procedure in 341 patients and screened as per inclusion/exclusion criteria (167 in the second-generation group and 174 in the third-generation group). Results: The number of male patients (86.2%) was more than female patients in our study population. MACEs were reported in 4.19% patients after 1 year duration, and the percentage of MACEs was more in the second-generation DES group (4.77%) than in the third-generation group (3.44%); however, statistical analysis has not found any significant difference (p = 0.534). The rate of myocardial infarction (1.19% vs. 0.57%) and stent thrombosis (1.8% vs. 1.15%) was more in the second-generation DES group. However, restenosis (1.19% vs. 1.15%) and cardiac death (0.59% vs. 0.57%) were almost same in both groups. A significant association was found between MACEs and diabetes mellitus (p = 0.025), hypertension (p = 0.035), smoking (p = 0.008), and a family history of CAD (p = 0.018). Conclusion: BP-BioMatrix and DP-XIENCE DES have comparable clinical outcomes. Findings of the current study will assist the policy makers and healthcare providers in the rationalization of scarce resources and evidence-based patient care. However, longer follow-up studies are required for convincing results.

Biomimetic Patch with Wicking-Breathable and Multi-mechanism Adhesion for Bioelectrical Signal Monitoring.

Wearable bioelectrical monitoring devices can provide long-term human health information such as electrocardiogram and other physiological signals. It is a crucial part of the remote medical system. These can provide prediction for the diagnosis and treatment of cardiovascular disease and access to timely treatment. However, the patch comfort of the wearable monitoring devices in long-term contact with the skin have been a technical bottleneck of the hardware. In this study, the biomimetic patch with wicking-breathable and multi-mechanism adhesion performance to achieve adaptability and comfortability to human skin has been reported. The patch was designed based on a conical through-hole and hexagonal microgroove to directionally transport sweat from skin to air which gives the patch the breathable performance. The breathable and drainage capability of the biomimetic patch was experimentally verified by analyzing the conical through-hole and hexagonal microgroove with the structural mechanism of wicking. Multi-mechanism adhesion of the Ag/Ni microneedle array and PDMS-t adhesion material ensures the stability of patch signal acquisition. This study provides a new way for enhancing the breathability and adaptability of the patch to realize accurate bioelectrical signal monitoring under sweat conditions on human skin.

Synthesis, Characterization, Biological Activity and Molecular Docking Studies of Novel Organotin(IV) Carboxylates.

Four new carboxylates complexes with general formula R2SnL2 and R3SnL, where R = n-butyl (1, 3), methyl (2, 4) and L = 4-Chlorophenoxyacetate, were synthesized in significant yields. FT-IR analysis revealed a chelating (1 and 2) and a bridging bidentate (3 and 4) coordination modes for the carboxylate ligand in solid state which was further confirmed by the single crystal X-ray analysis of complex 4. The NMR data (1H, 13C and 119Sn) revealed a higher coordination number around the tin center in R2SnL2 (1 and 2) compared to R3SnL (3 and 4). A close matching was observed between the experimental and calculated structures (obtained at B3LYP/6-31G* + LANL2DZ basis set). Quantum chemical analysis indicates that the carboxylate moiety has the major contribution in the formation of filled and unfilled orbitals as well as in ligand to ligand intramolecular charge transfer during the electronic transitions. The cytotoxicity data of the screened compounds evaluated against lung cancer cell line (A549) and normal lung fibroblast cell line (MRC-5) revealed that 1, 3 and 4 have shown dose dependent cytotoxic effects while HL and 2 have shown steady and low cytotoxic activities. The antibacterial activity of complexes 1-4 is higher than that of HL. Molecular docking study showed an intercalation binding mode for complex 3 with DNA (docking score = -3.6005) involving four polar interactions. Complex 3 docking with tubulin (PDB ID 1SA0) with colchicine as a target protein resulted in three polar interactions (docking score -5.2957). Further, the docking analysis of the HL and 1-4 has shown an adequate interactions with the coronavirus SARS-CoV-2 spike protein, nucleocapsid protein and human angiotensin converting enzyme (ACE2).

Enhanced photocatalytic potential of TiO2 nanoparticles in coupled CdTiO2 and ZnCdTiO2 nanocomposites.

Photodegradation of organic pollutants is the most suitable and cheaper technique to counter decontamination issues. Among the metal-based nanoparticles, TiO2 is considered to be the most effective heterogeneous photocatalyst for the photodegradation of organic pollutants. However, the large band gap and the high electron-hole pair recombination rate limit its practical applications. Herein, an approach was introduced to minimize the mentioned limitations by preparing CdTiO2 and ZnCdTiO2 nanocomposites by co-precipitation method. The as-synthesized TiO2, CdTiO2, and ZnCdTiO2 were characterized by scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and UV-visible spectrophotometry. Morphological analysis revealed that TiO2 are mostly agglomerated with different shapes and sizes and the nanocomposites are mostly in dispersed form. The components of the nanocomposites are strongly intercalated in the ternary nanocomposite as confirmed from TEM analysis. XRD analysis confirmed the anatase TiO2 while the UV-visible analysis showed the shifting toward higher wavelength. The band gap energy of TiO2 (2.65) decreased to 2.6 and 2.56 eV for CdTiO2 and ZnCdTiO2, respectively. BET analysis has shown a 47.2 m2/g surface area for the ternary ZnCdTiO2 nanocomposite. The photodegradation results revealed that TiO2, CdTiO2, and ZnCdTiO2 degraded about 74%, 86%, and 97.61% methylene blue dye, respectively, within 2 h. Maximum photodegradation is achieved in the basic medium and the ternary ZnCdTiO2 nanocomposite degraded 98% dye at pH 10.

A novel TanCAR targeting IL13Rα2 and EphA2 for enhanced glioblastoma therapy.

Chimeric antigen receptor T cell (CAR-T) therapy has been shown to be an effective strategy for combatting non-solid tumors; however, CAR-T therapy is still a challenge for solid tumors, such as glioblastoma. To improve CAR-T therapy for glioblastoma, a new TanCAR, comprising the tandem arrangement of IL13 (4MS) and EphA2 scFv, was generated and validated in vitro and in vivo. In vitro, the novel TanCAR-redirected T cells killed glioblastoma tumor cells by recognizing either IL-13 receptor α2 (IL13Rα2) or EphA2 alone or together upon simultaneous encounter of both targets, but did not kill normal cells bearing only the IL13Rα1/IL4Rα receptor. As further proof of principle, the novel TanCAR was tested in a subcutaneous glioma xenograft mouse model. The results indicated that the novel TanCAR-redirected T cells produced greater glioma tumor regression than single CAR-T cells. Thus, the novel TanCAR-redirected T cells kill gliomas more efficiently and selectively than a single IL13 CAR or EphA2 scFv CAR, with the potential for preventing antigen escape and reduced off-target cytotoxicity.

Synthesis, characterization, antioxidant, antileishmanial, anticancer, DNA and theoretical SARS-CoV-2 interaction studies of copper(II) carboxylate complexes.

Copper(II) carboxylate complexes [Cu2(OOCR)4L2] (1) and [Cu2(OOCR`)4OCO(R`)CuL2]n (2), where L = 2-methyl pyridine, R = 2-chlorophenyl acetate and R` = 2-fluorophenyl acetate were synthesized and characterized by FT-IR spectroscopy and single crystal X-ray analysis. Complex 1 exhibits the typical paddlewheel array of a dinuclear copper(II) complex with carboxylate ligands. In complex 2, this scaffold is further extended into a polymeric arrangement based on alternate paddlewheel and square planar moieties with distinct coordination spheres. The complexes showed better 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities and have been found to be more potent antileishmanial agents than their corresponding free ligand acid species. UV-Vis absorption titrations revealed good DNA binding abilities {Kb = 9.8 × 104 M-1 (1) and 9.9 × 104 M-1 (2)} implying partial intercalation of the complexes into DNA base pairs along with groove binding. The complexes displayed in vitro cytotoxic activity against malignant glioma U-87 (MG U87) cell lines. Computational docking studies further support complex-DNA binding by intercalation. Molecular docking investigations revealed probable interactions of the complexes with spike protein, the nucleocapsid protein of SARS-CoV-2 and with the angiotensin converting enzyme of human cells.

Synergetic adhesion in highly adaptable bio-inspired adhesive.

Biologically inspired adhesives microstructure requires enough flexibility to make a conformal attachment to the surface as well as high rigidity to maintain the mechanical stability of structure against buckling. To tackle these conflicting factors for the synthetic adhesives is a challenge towards large-scale production and utilizing in practical applications. Addressing this problem, we have fabricated a honeycomb structure with a soft elastic film, partially covering the cavity of the honeycomb pattern. Honeycomb structure provides enough support to maintain the structural stability of the microstructure and soft PDMS film over the pattern provides sufficient flexibility to form a strong attachment with the target surface. Meanwhile, the resemblance of the designed structure to the octopi's sucker generates a negative pressure resulting in suction forces. To justify this suction effect, we compared our results with other controlled honeycomb microstructures (1) without any elastic film (2) with elastic film covering the whole cavity of the honeycomb pattern. Experimental results and theoretical prediction demonstrate the synergistic role of van der Waals and suction forces in the proposed partial-film honeycomb microstructure. The synergistic role of adhesive forces makes this structure a stronger, durable, and surface adaptable adhesive. We also investigated the critical role of the viscous forces for our proposed microstructure in water and silicon oil wetting conditions which signify the contribution of capillary forces.

Monitoring of frying process in canola oil blend using fourier transform infrared and chemometrics techniques.

The production of trans-fats and chemical changes during the process of frying are serious public health concerns and must be monitored efficiently. For this purpose, the canola oil was formulated with different ratio of extra virgin olive oil and palm olein using D-optimal mixture design, and the best formulation (67:22:11) based on free fatty acid (FFA) content, peroxide value (PV), and iodine value (IV) as responses was selected for multiple frying process. The data on FFA, PV, and IV along with Fourier transform-infrared (FT-IR) spectra were taken after each frying up to ten frying. The spectral data were preprocessed with standard normal variate followed by principal component analysis which is clearly showing the differentiation for various frying. Similarly, partial least square regression was applied to predict the FFA (0.37%-1.63%), PV (4.47-13.85 meqO2/kg), and IV (111.51-51.39 I2/100 g) which demonstrated high coefficient of determination (R2) 0.84, 0.83, and 0.81, respectively. It can be summarized that FT-IR can be used as a novel tool for fast and noninvasive quality determination of frying oils.

Biallelic TMEM251 variants in patients with severe skeletal dysplasia and extreme short stature.

Skeletal dysplasias are a heterogeneous group of disorders ranging from mild to lethal skeletal defects. We investigated two unrelated families with individuals presenting with a severe skeletal disorder. In family NMD02, affected individuals had a dysostosis multiplex-like skeletal dysplasia and severe short stature (<-8.5 SD). They manifested increasingly coarse facial features, protruding abdomens, and progressive skeletal changes, reminiscent of mucopolysaccharidosis. The patients gradually lost mobility and the two oldest affected individuals died in their twenties. The affected child in family ID01 had coarse facial features and severe skeletal dysplasia with clinical features similar to mucopolysaccharidosis. She had short stature, craniosynostosis, kyphoscoliosis, and hip-joint subluxation. She died at the age of 5 years. Whole-exome sequencing identified two homozygous variants c.133C>T; p.(Arg45Trp) and c.215dupA; p.(Tyr72Ter), respectively, in the two families, affecting an evolutionary conserved gene TMEM251 (NM_001098621.1). Immunofluorescence and confocal studies using human osteosarcoma cells indicated that TMEM251 is localized to the Golgi complex. However, p.Arg45Trp mutant TMEM251 protein was targeted less efficiently and the localization was punctate. Tmem251 knockdown by small interfering RNA induced dedifferentiation of rat primary chondrocytes. Our work implicates TMEM251 in the pathogenesis of a novel disorder and suggests its potential function in chondrocyte differentiation.

Microscopic and molecular evidence in support of rodent as a reservoir for dissemination of Leishmaniasis.

Leishmaniasis is a worldwide public health problem and vector-borne disease. It is caused by a diverse group of protozoan parasites that belong to the genus Leishmania and transmitted to humans through a bite of an infected female sand fly. Leishmaniasis has attained epidemic proportion in Khyber Pakhtunkhwa and raises serious concern over its management. The present research work was conducted in cutaneous leishmaniasis (CL) prevalent village named Surgul of district Kohat, Khyber Pakhtunkhwa with a focus to investigate whether rodent can act as a source for dissemination of leishmanial species or not. In this context, rodent samples were analyzed via morphological and molecular approaches to unveil prevalence of CL. It was reported that 12.5% of samples were positive for signs of leishmaniasis through microscopy and 18.75% through polymerase chain reaction (PCR). Supporting the findings further, the color character of rodents was also taken into consideration, which shows that light dark colored rodents were more infected (13.3%) compared to brown colored rodents (11.43%). Based on our findings, we speculate that small rodents are a possible reservoir of various leishmanial parasites and play a significant role in zoonosis and maintenance of their species.

RIN2 and BBS7 variants as cause of a coincidental syndrome.

BBS7 and RIN2 variants cause Bardet Biedl syndrome and RIN2 syndrome respectively. We investigated a consanguineous family in which five individuals manifested different phenotypes. Whole-exome sequencing analyses of the individual with multiple phenotypes revealed homozygosity for novel pathogenic variants in his DNA sample; a frameshift variant in RIN2 (c.1938delT) and a splice-site variant in BBS7 (c.1677-1G > A). Other affected individuals were homozygous for a variant in only one of either gene and consequently manifested phenotypes respective to one disorder. Our work shows that exome sequencing of the most severely affected individual can help in the identification of pathogenic variants in more than one involved genes in a particular family.

Functional quality of optimized peach-based beverage developed by application of ultrasonic processing.

The influence of thermal treatment (at 90°C for 10 min) and sonication (at 20 kHz and 130 W for 30, 60, and 90 min on room temperature) on the physicochemical properties, bioactive compounds, antioxidant activity, and organic acids of fresh formulated functional peach beverage was investigated. The results indicated that conventional pasteurization and sonication treatment did not show any significant changes in pH value and Brix amount of juice, and however, a rise in cloud value was observed under all processing conditions. The thermal treatment caused the decrement in total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (assessed by diphenyl dipicryl hydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)), and organic acids of juice, whereas sonication treatment for 90 min increased maximum the activity of bioactive compounds (TPC: 600.61 µg/100 ml; TFC: 177 µg CE/100 ml), antioxidants (DPPH: 51.87%; FRAP: 506.13 µmol Trolox/L; ABTS: 1,507.375 µmol Trolox/L), and organic acids (malic acid: 998; citric acid: 128; oxalic acid: 145; shikimic acid: 63 µg/100 ml) as compared to other treatment conditions and control. Multivariate data analysis was done by principal component analysis as it identifies patterns in data by comparing data sets which is further expressed based on their similarities and discriminations, respectively.

The Intercalation of CORM-2 with Pharmaceutical Clay Montmorillonite (MMT) Aids for Therapeutic Carbon Monoxide Release.

The pharmaceutical clay montmorillonite (MMT) is, for the first time, explored as a carbon monoxide-releasing material (CORMat). MMT consists of silicate double layered structure; its exfoliation feature intercalate the CORM-2 [RuCl(µ-Cl)(CO)3]2 inside the layers to suppress the toxicity of organometallic segment. The infrared spectroscopy (IR) confirmed the existence of ruthenium coordinated carbonyl ligand in MMT layers. The energy-dispersive X-ray spectroscopy (EDX) analysis showed that ruthenium element in this material was about 5%. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed that the layer-structure of MMT has been maintained after loading the ruthenium carbonyl segment. Moreover, the layers have been stretched out, which was confirmed by X-ray diffraction (XRD) analysis. Thermogravimetric (TG) curves with huge weight loss around 100-200 °C were attributed to the CO hot-release of ruthenium carbonyl as well as the loss of the adsorbed solvent molecules and the water molecules between the layers. The CO-liberating properties have been assessed through myoglobin assay. The horse myoglobin test showed that the material could be hydrolyzed to slowly release carbon monoxide in physiological environments. The half-life of CO release was much longer than that of CORM-3, and it has an excellent environmental tolerance and slow release effect.

The negative impact of cadmium on nitrogen transformation processes in a paddy soil is greater under non-flooding than flooding conditions.

Nitrification and denitrification are two important processes in the nitrogen (N) cycle. Under heavy-metal pollution with water management of paddy soils, these two processes are not well understood. This study aimed to examine the effect of cadmium (Cd) on N transformation under flooding and non-flooding conditions. A paddy soil was incubated under two water regimes (flooding and non-flooding) and four Cd levels (0, 2, 5 and 10 mg kg-1). The availability of Cd was higher in the non-flooding than flooding conditions. Cadmium contamination significantly (p ≤ 0.05) decreased the copy number of archaeal and bacterial amoA genes, bacterial nirS, nirK and nosZ genes under both conditions with the decrease being greater under non-flooding. High level of Cd (10 mg kg-1) was more toxic in non-flooding than flooding conditions to the nitrifiers and denitrifiers, which in turn decreased N transformation through microbially-mediated processes. Its contamination decreased N2O emission initially under both water regimes but the effect was greater under the non-flooding condition. However, the non-significant stimulatory effect of Cd on N2O emission was observed during the late phase. The microbial community structure was changed with time and water regimes. Irrespective of water regime, the dominated fungal phyla were Ascomycota and Basidiomycota while the dominated bacteria phyla were Actinobacteria, Proteobacteria, Firmicutes and Acidobacteria. In summary, water regimes and Cd bioavailability changed soil N transformations via microbial mediated processes.