Enzyme System Research Articles

Biodegradation of Pharmaceutical Pollutants Using Fungal Enzyme

Abstract: The potential of filamentous fungi and their enzymes are investigated for bioremediating pharmaceutical pollutants from wastewater thereby addressing the growing concern of emerging pollutants in water resources. Among the various microorganisms, the current abstract discusses the role of fungi in degrading antibiotics and persistent pharmaceutical compounds. These fungi allow the biodegradation via the formation of highly oxidative hydroxyl radicals. It summarizes the role of both intra (cytochrome P450) and extracellular (laccase) enzyme systems for the bioremediation of emerging clinical pollutants. It emphasizes the importance of both biosorption and biodegradation for effective pollutant removal by breaking down pharmaceuticals (e.g. antibiotics) and other hazardous compounds (e.g. endocrine-disrupting compounds, polycyclic aromatic hydrocarbons). Although the enzymes CYP450 are not directly engaged, their metabolic pathways execute mechanisms such as oxidation, the formation of reactive intermediates, and chemical modification, all of which result in the degradation of clinical pollutants. Amongst all enzyme systems in the case of laccase which oxidise a wide spectrum of substrates, converts them to free radicals. Additionally, the role of recombinant enzyme production and transgenic strains for pollutant degradation has also been elaborated. These considerations emphasise the need for ongoing research and biotechnological advancements to address the growing concern of pharmaceuticals and personal care product pollutants in water systems.

Impact of nutritional risk factors on the development of multiple sclerosis

The literature review considers the data on the assessment of the influence of alimentary factors on the development of a severe neurological disease - multiple sclerosis (MS). MS is a polyetiologic disease, the risk of development of which is influenced by both infectious (Epstein-Barr virus, herpes simplex virus, influenza virus, etc.) and noninfectious factors (genetic predisposition, smoking, geographic region of residence, etc.). MS is a progressive demyelinating disease of the central nervous system (CNS), which leads to neurodegeneration accompanied by a variety of clinical manifestations. The pathogenesis of MS is characterized by immune-mediated damage to the myelin sheaths of nerve fibers, which is manifested by inflammation, neurosynaptic damage, and destruction of white matter, axons, and blood vessels. Rapid non-evolutionary dietary and lifestyle changes, which are driven by urbanization, industrialization and globalization of the food market, are leading to an increase in most chronic non-communicable diseases, including MS. The effects induced by alimentary factors are due to changes in the microbial composition of the gastrointestinal tract (GIT), immune cell function, enzyme systems functioning, etc. The aim of the work is to study the influence of micro/macronutrients, as well as the nature of the diet on the risk of MS development, to assess the role of nutrition in the primary prevention of MS. It has been shown that a diet characterized by a high content of animal fats and trans-isomers of fatty acids (TFA), increased consumption of meat products, but low content of vegetables, fruits and whole-grain products is associated with a higher risk of MS development. Regular inclusion in the diet of sources of polyunsaturated fatty acids (PUFAs) (vegetable oils, seeds, nuts, marine fish) and vitamin D (fatty fish, caviar, butter, egg yolk) leads to lower relapse rates and less new brain lesions among MS patients. The literature review was conducted using open sources posted in electronic databases: PubMed, Medline, Scopus, Google Scholar, World Bank publications, WHO, eLibrary, Cyberleninka, Web of Science.

OPFR removal by white rot fungi: screening of removers and approach to the removal mechanism

The persistent presence of organophosphate flame retardants (OPFRs) in wastewater (WW) effluents raises significant environmental and health concerns, highlighting the limitations of conventional treatments for their remotion. Fungi, especially white rot fungi (WRF), offer a promising alternative for OPFR removal. This study sought to identify fungal candidates (from a selection of four WRF and two Ascomycota fungi) capable of effectively removing five frequently detected OPFRs in WW: tributyl phosphate (TnBP), tributoxy ethyl phosphate (TBEP), trichloroethyl phosphate (TCEP), trichloro propyl phosphate (TCPP) and triethyl phosphate (TEP). The objective was to develop a co-culture approach for WW treatment, while also addressing the utilization of less assimilable carbon sources present in WW. Research was conducted on carbon source uptake and OPFR removal by all fungal candidates, while the top degraders were analyzed for biomass sorption contribution. Additionally, the enzymatic systems involved in OPFR degradation were identified, along with toxicity of samples after fungal contact. Acetate (1.4 g·L-1), simulating less assimilable organic matter in the carbon source uptake study, was eliminated by all tested fungi in 4 days. However, during the initial screening where the removal of four OPFRs (excluding TCPP) was tested, WRF outperformed Ascomycota fungi. Ganoderma lucidum and Trametes versicolor removed over 90% of TnBP and TBEP within 4 days, with Pleorotus ostreatus and Pycnoporus sanguineus also displaying effective removal. TCEP removal was challenging, with only G. lucidum achieving partial removal (47%). A subsequent screening with selected WRF and the addition of TCPP revealed TCPP’s greater susceptibility to degradation compared to TCEP, with T. versicolor exhibiting the highest removal efficiency (77%). This observation, plus the poor degradation of TEP by all fungal candidates suggests that polarity of an OPFR inversely correlates with its susceptibility to fungal degradation. Sorption studies confirmed the ability of top-performing fungi of each selected OPFR to predominantly degrade them. Enzymatic system tests identified the CYP450 intracellular system responsible for OPFR degradation, so reactions of hydroxylation, dealkylation and dehalogenation are possibly involved in the degradation pathway. Finally, toxicity tests revealed transformation products obtained by fungal degradation to be more toxic than the parent compounds, emphasizing the need to identify them and their toxicity contributions. Overall, this study provides valuable insights into OPFR degradation by WRF, with implications for future WW treatment using mixed consortia, emphasizing the importance of reducing generated toxicity.

Establishing a biochemical understanding of the initiation of chromosome replication in bacteria

In the mid-1950s, Arthur Kornberg elucidated the enzymatic synthesis of DNA by DNA polymerase, for which he was recognized with the 1959 Nobel Prize in Physiology or Medicine. He then identified many of the proteins that cooperate with DNA polymerase to replicate duplex DNA of small bacteriophages. However, one major unanswered problem was understanding the mechanism and control of the initiation of chromosome replication in bacteria. In a seminal paper in 1981, Fuller, Kaguni, and Kornberg reported the development of a cell-free enzyme system that could replicate DNA that was dependent on the bacterial origin of DNA replication, oriC. This advance opened the door to a flurry of discoveries and important papers that elucidated the process and control of initiation of chromosome replication in bacteria.

Parascedosporium putredinis NO1 tailors its secretome for different lignocellulosic substrates.

Parascedosporium putredinis NO1 is a plant biomass-degrading ascomycete with a propensity to target the most recalcitrant components of lignocellulose. Here we applied proteomics and activity-based protein profiling (ABPP) to investigate the ability of P. putredinis NO1 to tailor its secretome for growth on different lignocellulosic substrates. Proteomic analysis of soluble and insoluble culture fractions following the growth of P. putredinis NO1 on six lignocellulosic substrates highlights the adaptability of the response of the P. putredinis NO1 secretome to different substrates. Differences in protein abundance profiles were maintained and observed across substrates after bioinformatic filtering of the data to remove intracellular protein contamination to identify the components of the secretome more accurately. These differences across substrates extended to carbohydrate-active enzymes (CAZymes) at both class and family levels. Investigation of abundant activities in the secretomes for each substrate revealed similar variation but also a high abundance of "unknown" proteins in all conditions investigated. Fluorescence-based and chemical proteomic ABPP of secreted cellulases, xylanases, and β-glucosidases applied to secretomes from multiple growth substrates for the first time confirmed highly adaptive time- and substrate-dependent glycoside hydrolase production by this fungus. P. putredinis NO1 is a promising new candidate for the identification of enzymes suited to the degradation of recalcitrant lignocellulosic feedstocks. The investigation of proteomes from the biomass bound and culture supernatant fractions provides a more complete picture of a fungal lignocellulose-degrading response. An in-depth understanding of this varied response will enhance efforts toward the development of tailored enzyme systems for use in biorefining.IMPORTANCEThe ability of the lignocellulose-degrading fungus Parascedosporium putredinis NO1 to tailor its secreted enzymes to different sources of plant biomass was revealed here. Through a combination of proteomic, bioinformatic, and fluorescent labeling techniques, remarkable variation was demonstrated in the secreted enzyme response for this ascomycete when grown on multiple lignocellulosic substrates. The maintenance of this variation over time when exploring hydrolytic polysaccharide-active enzymes through fluorescent labeling, suggests that this variation results from an actively tailored secretome response based on substrate. Understanding the tailored secretomes of wood-degrading fungi, especially from underexplored and poorly represented families, will be important for the development of effective substrate-tailored treatments for the conversion and valorization of lignocellulose.

Leveraging Limited Experimental Data with Machine Learning: Differentiating a Methyl from an Ethyl Group in the Corey-Bakshi-Shibata Reduction.

We present a case study on how to improve an existing metal-free catalyst for a particularly difficult reaction, namely, the Corey-Bakshi-Shibata (CBS) reduction of butanone, which constitutes the classic and prototypical challenge of being able to differentiate a methyl from an ethyl group. As there are no known strategies on how to address this challenge, we leveraged the power of machine learning by constructing a realistic (for a typical laboratory) small, albeit high-quality, data set of about 100 reactions (run in triplicate) that we used to train a model in combination with a key-intermediate graph (of substrate and catalyst) to predict the differences in Gibbs activation energies ΔΔG‡ of the enantiomeric reaction paths. With the help of this model, we were able to select and subsequently screen a small selection of catalysts and increase the selectivity for the CBS reduction of butanone to 80% enantiomeric excess (ee), the highest possible value achieved to date for this substrate with a metal-free catalyst, thereby also exceeding the best available enzymatic systems (64% ee) and the selectivity with Corey's original catalyst (60% ee). This translates into a >50% improvement in relative ΔG‡ from 0.9 to 1.4 kcal mol-1. We underscore the transformative potential of machine learning in accelerating catalyst design because we rely on a manageable small data set and a key-intermediate graph representing a combination of catalyst and substrate graphs in lieu of a transition-state model. Our results highlight the synergy of synthetic chemistry and data-centric approaches and provide a blueprint for future catalyst optimization.

КОФЕЙНАЯ КИСЛОТА СТИМУЛИРУЕТ СВЕЧЕНИЕ МИЦЕЛИЯ ВЫСШИХ ГРИБОВ NEONOTHOPANUS NAMBI, ARMILLARIA BOREALIS IN VIVO

In vivo experiments have shown that the addition of caffeic acid to the luminous mycelia of the higher fungi Neonothopanus nambi and Armillaria borealis stimulates a rapid and significant (by an order of magnitude or more) increase in the intensity of their light emission. It has been suggested that the observed effect of fungal luminescence activation may be mediated by the oxidation of caffeic acid by enzymes of the ligninolytic complex of basidiomycetes (in particular, by peroxidases) with the emission of visible light quanta. Comparative in vivo experiments showed that the addition of hispidin (the precursor of luciferin in the light emission reaction of higher fungi) did not affect the intensity of bioluminescence of the mycelia. At the same time, in vitro studies found that caffeic acid significantly suppressed the NADPH-hispidin-activated emission reaction of luminescent systems isolated from the mycelia of N. nambi and A. borealis. The inhibitory effect of caffeic acid is considered and discussed in the work from the standpoint of the classical biochemistry concept on enzyme inhibition by the reaction product according to the negative feedback principle. In general, the results obtained develop and supplement the understanding of the mechanisms of light emission in higher fungi and testify in favor of the fact that the generation of visible light quanta in basidiomycetes can be carried out by different biochemical pathways involving different enzymes (or enzyme systems). Clarifying the mechanism of stimulation of in vivo bioluminescence of higher fungi by caffeic acid is a priority for further research.

Investigation of the Effects of Mutating Iron-Coordinating Residues in Rieske Dioxygenases

Rieske dioxygenases are multi-component enzyme systems, naturally found in many soil bacteria, that have been widely applied in the production of fine chemicals, owing to the unique and valuable oxidative dearomatization reactions they catalyze. The range of practical applications for these enzymes in this context has historically been limited, however, due to their limited substrate scope and strict selectivity. In an attempt to overcome these limitations, our research group has employed the tools of enzyme engineering to expand the substrate scope or improve the reactivity of these enzyme systems in specific contexts. Traditionally, enzyme engineering campaigns targeting metalloenzymes have avoided mutations to metal-coordinating residues, based on the assumption that these residues are essential for enzyme activity. Inspired by the success of other recent enzyme engineering reports, our research group investigated the potential to alter or improve the reactivity of Rieske dioxygenases by altering or eliminating iron coordination in the active site of these enzymes. Herein, we report the modification of all three iron-coordinating residues in the active site of toluene dioxygenase both to alternate residues capable of coordinating iron, and to a residue that would eliminate iron coordination. The enzyme variants produced in this way were tested for their activity in the cis-dihydroxylation of a small library of potential aromatic substrates. The results of these studies demonstrated that all three iron-coordinating residues, in their natural state, are essential for enzyme activity in toluene dioxygenase, as the introduction of any mutations at these sites resulted in a complete loss of cis-dihydroxylation activity.

Гідроген сульфід: біологічні та патохімічні ефекти

Hydrogen sulfide (H2S) belongs to the family of «gasotransmitters» can by synthesized by enzymatic systems and also formed non-enzymatically. At physiological concentrations, it regulates a range of biological functions in various organs and tissues. H2 S is involved in biochemical changes that play an important role in the pathogenesis of diseases such as cancer, COVID-19, diabetes mellitus, and neurodegenerative pathologies. In carcinogenesis, H2S influences cancer cell proliferation, inhibits cancer cell apoptosis, regulates the cell cycle, intracellular signaling pathways, stimulates angiogenesis, and autophagy of cancer cells. In lung inflammation caused by COVID-19, H2S disrupts disulfide bonds in mucus, reducing its viscosity, blocks NF-κB pathway activation, preventing the onset of a «cytokine storm», promotes Nrf2 activation, increasing the expression of antioxidant molecules and enzymes, activates potassium channels, and blocks Na+/K+-ATPase, promoting electrolyte absorption. In the pancreas, H 2 S regulates insulin secretion and plays a significant role in insulin sensitivity regulation in insulin-responsive tissues. It inhibits glucose uptake and glycogen accumulation, which is crucial in diabetes mellitus. In adipose tissue, H 2 S promotes adipogenesis, inhibits lipolysis, and regulates the secretion of adiponectin and MCP-1 in type 2 diabetes. In neural tissue, H2S acts as a neuromodulator, increases GABA expression, induces Ca2+ concentration increase, participates in long-term potentiation, neurotransmitter modulation, affects NADPH levels, and exerts epigenetic effects. Understanding the role of H2 S may be crucial in developing effective therapy strategies for various diseases.

Antioxidative effect of wheat-grain moxibustion on cyclophosphamide-induced liver injury in mice based on Nrf2-Keap1 signaling pathway

To observe the protective effect of wheat-grain moxibustion on cyclophosphamide (CTX)-induced liver injury in mice, and explore its mechanism based on the nuclear factor E2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) signaling pathway. Twenty-four male CD-1 (ICR) mice were randomly divided into a blank group, a model group, and a moxibustion group, with 8 mice in each group. The mice in the model group and the moxibustion group were intraperitoneally injected with CTX (80 mg/kg) to induce liver injury. The mice in the moxibustion group were treated with wheat-grain moxibustion at "Guanyuan" (CV 4) and bilateral "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), with each acupoint being treated by 3 cones, approximately 30 seconds per cone, once daily for 7 days. After intervention, the general condition of the mice was observed; the liver mass was measured and the liver index was calculated; HE staining was used to observe the morphology of the liver, and the liver tissue pathological score was assessed; ELISA was used to detect the serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamate dehydrogenase (GLDH) and the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) in the liver; Western blot and real-time fluorescence quantitative PCR were used to detect the protein and mRNA expression of Nrf2, Keap1, and quinione acceptor oxidoreductase 1 (NQO1) in the liver. Compared with the blank group, the mice in the model group showed sluggishness, unsteady gait, and decreased body weight; liver index was increased (P<0.01); liver cells were loosely arranged, with a small number of cell swollen and exhibiting balloon-like changes; liver tissue pathological score was increased (P<0.05); the serum levels of AST, ALT, GLDH, and level of MDA in the liver were increased (P<0.05), and the levels of SOD and GSH-Px in the liver were decreased (P<0.05); protein and mRNA expression of Nrf2 and NQO1 in the liver was decreased (P<0.01), protein and mRNA expression of Keap1 in the liver was increased (P<0.01). Compared with the model group, the mice in the moxibustion group showed improvement in general condition; liver index was decreased (P<0.01); liver cell structure was relatively intact and clear, and liver tissue pathological score was decreased (P<0.05); the serum levels of AST, ALT, GLDH, and level of MDA in the liver were decreased (P<0.05), and the levels of SOD and GSH-Px in the liver were increased (P<0.05, P<0.01); protein and mRNA expression of Nrf2 and NQO1 in the liver was increased (P<0.05), protein and mRNA expression of Keap1 in the liver was decreased (P<0.05). The wheat-grain moxibustion may alleviate CTX-induced liver injury by activating the Nrf2-Keap1 signaling pathway and enhancing the expression of antioxidative enzyme system in the body.

A multilevel investigation to reveal the regulatory mechanism of lignin accumulation in juice sac granulation of pomelo

Granulation of juice sacs is a physiological disorder, which affects pomelo fruit quality. Here, the transcriptome and ubiquitinome of the granulated juice sacs were analyzed in Guanxi pomelo. We found that lignin accumulation in the granulated juice sacs was regulated at transcription and protein modification levels. In transcriptome data, we found that the genes in lignin biosynthesis pathway and antioxidant enzyme system of the granulated juice sacs were significantly upregulated. However, in ubiquitinome data, we found that ubiquitinated antioxidant enzymes increased in abundance but the enzyme activities decreased after the modification, which gave rise to reactive oxygen species (ROS) contents in granulated juice sacs. This finding suggests that ubiquitination level of the antioxidant enzymes is negatively correlated with the enzyme activities. Increased H2O2 is considered to be a signaling molecule to activate the key gene expressions in lignin biosynthesis pathway, which leads to the lignification in granulated juice sacs of pomelo. This regulatory mechanism in juice sac granulation of pomelo was further confirmed through the verification experiment using tissue culture by adding H2O2 or dimethylthiourea (DMTU). Our findings suggest that scavenging H2O2 and other ROS are important for reducing lignin accumulation, alleviating juice sac granulation and improving pomelo fruit quality.

Degradation of petroleum hydrocarbon contaminants by Rhodococcus erythropolis KB1 synergistic with alfalfa (Medicago sativa L.).

Petroleum hydrocarbons are a stubborn pollutant that is difficult to degrade globally, and plant-microbial degradation is the main way to solve this type of pollutant. In this study, the physiological and ecological responses of alfalfa to petroleum hydrocarbons in different concentrations of petroleum hydrocarbon-contaminated soil with KB1 (Rhodococcus erythropolis) were analyzed and determined by laboratory potting techniques. The growth of alfalfa (CK) and alfalfa with KB1 (JZ) in different concentrations of petroleum hydrocarbons contaminated soil was compared and analyzed. The results of the CK group showed that petroleum hydrocarbons could significantly affect the activity of alfalfa antioxidant enzyme system, inhibit the development of alfalfa roots and the normal growth of plants, especially in the high-concentration group. KB1 strain had the ability to produce IAA, form biofilm, fix nitrogen, produce betaine and ACC deaminase, and the addition of KB1 could improve the growth traits of alfalfa in the soil contaminated with different concentrations of petroleum hydrocarbons, the content of soluble sugars in roots, and the stress resistance and antioxidant enzyme activities of alfalfa. In addition, the degradation kinetics of the strain showed that the degradation rate of petroleum could reach 75.2% after soaking with KB1. Furthermore, KB1 can efficiently degrade petroleum hydrocarbons in advance and significantly alleviate the damage of high concentration of petroleum hydrocarbons to plant roots. The results showed that KB1 strains and alfalfa plants could effectively enhance the degradation of petroleum hydrocarbons, which provided new ideas for improving bioremediation strategies.

Understanding Coenzyme Q.

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid sidechain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) and in several other cellular processes. In fact, CoQ appears to be central to the redox balance of the cell. Remarkably, its structure and properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox active molecule in the ETC and other enzymatic systems, its role as a pro-oxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

SlCarE054 in Spodoptera litura (Lepidoptera: Noctuidae) showed direct metabolic activity to β-cypermethrin with stereoselectivity.

Carboxylesterases (CarEs) is an important detoxification enzyme system in phase Ⅰ participating in insecticides resistance. In our previous study, SlCarE054, a CarEs gene from lepidoptera class, was screened out to be upregulated in a pyrethroids and organophosphates resistant population. Its overexpression was verified in two field-collected populations of Spodoptera litura (Lepidoptera: Noctuidae) resistant to pyrethroids and organophosphates by qRT-PCR. Spatiotemporal expression results showed that SlCarE054 was highly expressed in the pupae stage and the digestive tissue midgut. To further explore its role in pyrethroids and organophosphates resistance, its metabolism activity to insecticides was determined by UPLC. Its recombinant protein showed significant metabolism activity to cyhalothrin and fenvalerate, but not to phoxim or chlorpyrifos. The metabolic activity of SlCarE054 to β-cypermethrin showed stereoselectivity, with higher metabolic activity to θ-cypermethrin than the enantiomer α-cypermethrin. The metabolite of β-cypermethrin was identified as 3-phenoxybenzaldehyde. Further modelling and docking analysis indicated that β-cypermethrin, cyhalothrin and fenvalerate could bind with the catalytic triad of the 3D structure of SlCarE054. The interaction of β-cypermethrin with SlCarE054 also showed the lowest binding energy. Our work provides evidence that SlCarE054 play roles in β-cypermethrin resistance in S. litura.

Chromosome-scale genome assembly clarifies the mechanism of flooding tolerance and evolutionary history of Myricaria laxiflora

Myricaria laxiflora, belonging to the Tamaricaceae family, is a valuable plant resource naturally occurring along the riverbanks of the Yangtze River Basin. In this study, we constructed a chromosome-level M. laxiflora genome which was 1.34 Gb in size, with 12 chromosomes and a contig N50 of 11.69 Mb. In total, 23,719 protein-coding genes were discovered across the M. laxiflora genome. Phylogenetic investigation indicated that Tamaricaceae and Polygonaceae diverged between 65 and 81 million years ago (Mya). M. laxiflora underwent one whole genome duplication (WGD) between 19.74 and 24.60 Mya, and experienced a long terminal repeat (LTR) insertion around 0.15 Mya. These genomic changes may be related to environmental upheavals (such as the uplift of the Qinghai-Tibet Plateau) experienced by M. laxiflora during its evolution, and also may have provided a foundation for its evolution and adaptation. To analyze the flooding adaption mechanism of M. laxiflora, we compared morphological, physiological, and transcriptomic changes under control and submerged conditions. Overall, M. laxiflora was found to adopt a "quiescence" strategy when completely submerged. Specifically, in response to submersion, photosynthesis weakens, growth stagnates, glycolysis is activated, and the antioxidant enzyme system is enhanced. The “ethylene response pathway” was ascertained as a likely regulator of this process, and a MlERF-VII gene (Mla11G026380) may be the key gene regulating this process. Our findings shed light on the underlying mechanisms behind the flooding resistance displayed by M. laxiflora, while also establishing a basis for the conservation of its genetic resources.

Exploring the molecular mechanisms of melatonin-induced tolerance to salt-alkali stress in Populus cathayana × canadansis 'Xinlin 1′

Melatonin is widely recognized as involved in a wide range of plant growth and development functions. Research has primarily focused on herbaceous plants, with few findings on the function of melatonin in supporting tree growth. In this study, it was demonstrated that melatonin, as an endogenous hormone, considerably contributed towards the increased tolerance of poplar to salt-alkali stress. Transcriptome and metabolome analysis revealed that melatonin may enhance the cellular protection and antioxidant mechanisms of poplar and improve salt-alkali tolerance by regulating genes and metabolites involved in photosynthesis, antioxidant enzyme systems, plant hormone signal transduction pathways, and in the flavonoid as well as the melatonin biosynthesis pathway. The results of this study not only aid our increased understanding of the potential roles of melatonin in salt-alkali stress but also shed light on the potential mechanisms of the economically important woody model plant, poplar, involved in resisting abiotic stress.

Ti3C2Tx MXene nanosheet-based drug delivery/cascaded enzyme system for combination cancer therapy and anti-inflammation

Photothermal therapy (PTT)-based combination therapy is an effective approach to cancer treatment. However, there is a possibility of tumor development due to the inflammation caused by PTT. In addition, hyperthermia can cause damage to normal tissues. This work reported a drug delivery/cascade enzyme system based on Ti3C2Tx MXene nanosheets. Ultra-small, degradable mesoporous silica nanoparticles (DS-MSN) were prepared to load phloretin (Phl), which has anti-inflammatory, antioxidant, and anticancer properties. Subsequently, glucose oxidase (GOx) was adsorbed on the surface of DS-MSN. The nanoparticles were then modified on Ti3C2Tx MXene nanosheets and finally treated with polyethylene glycol (PEG) to obtain the multifunctional system named Ti3C2Tx-Phl@DS-MSN-GOx-PEG (TPDMGP). The high near-infrared photothermal conversion efficiency of Ti3C2Tx made it suitable for PTT. GOx and Ti3C2Tx formed a cascade enzyme system inside cancer cells: Ti3C2Tx exhibited catalase (CAT)-like activity that decomposed intracellular hydrogen peroxide (H2O2) into O2, which was provided to GOx for enhanced starvation therapy. GOx in the presence of O2 produces H2O2, for the oxygen production of Ti3C2Tx. Meanwhile, DS-MSN could be degraded in the reducing environment inside cancer cells as it contains disulfide bonds in its backbone, thus releasing Phl for chemotherapy. Such a combination therapy strategy could achieve a satisfactory therapeutic outcome by low-temperature PTT while evading normal tissue damage by high temperature. The anti-inflammatory effects of both Ti3C2Tx and Phl enabled TPDMGP to eliminate the inflammation caused by PTT via the scavenging of reactive oxygen species (ROS). The multifunctional system is expected to generate new paradigms for cancer PTT.

Utilizing transcriptomics and proteomics to unravel key genes and proteins of Oryza sativa seedlings mediated by selenium in response to cadmium stress

BackgroundCadmium (Cd) pollution has declined crop yields and quality. Selenium (Se) is a beneficial mineral element that protects plants from oxidative damage, thereby improving crop tolerance to heavy metals. The molecular mechanism of Se-induced Cd tolerance in rice (Oryza sativa) is not yet understood. This study aimed to elucidate the beneficial mechanism of Se (1 mg/kg) in alleviating Cd toxicity in rice seedlings.ResultsExogenous selenium addition significantly improved the toxic effect of cadmium stress on rice seedlings, increasing plant height and fresh weight by 20.53% and 34.48%, respectively, and increasing chlorophyll and carotenoid content by 16.68% and 15.26%, respectively. Moreover, the MDA, ·OH, and protein carbonyl levels induced by cadmium stress were reduced by 47.65%, 67.57%, and 56.43%, respectively. Cell wall metabolism, energy cycling, and enzymatic and non-enzymatic antioxidant systems in rice seedlings were significantly enhanced. Transcriptome analysis showed that the expressions of key functional genes psbQ, psbO, psaG, psaD, atpG, and PetH were significantly up-regulated under low-concentration Se treatment, which enhanced the energy metabolism process of photosystem I and photosystem II in rice seedlings. At the same time, the up-regulation of LHCA, LHCB family, and C4H1, PRX, and atp6 functional genes improved the ability of photon capture and heavy metal ion binding in plants. Combined with proteome analysis, the expression of functional proteins OsGSTF1, OsGSTU11, OsG6PDH4, OsDHAB1, CP29, and CabE was significantly up-regulated under Se, which enhanced photosynthesis and anti-oxidative stress mechanism in rice seedlings. At the same time, it regulates the plant hormone signal transduction pathway. It up-regulates the expression response process of IAA, ABA, and JAZ to activate the synergistic effect between each cell rapidly and jointly maintain the homeostasis balance.ConclusionOur results revealed the regulation process of Se-mediated critical metabolic pathways, functional genes, and proteins in rice under cadmium stress. They provided insights into the expression rules and dynamic response process of the Se-mediated plant resistance mechanism. This study provided the theoretical basis and technical support for crop safety in cropland ecosystems and cadmium-contaminated areas.

An Innovative Layer-by-Layer Edible Coating to Regulate Oxidative Stress and Ascorbate–Glutathione Cycle in Fresh-Cut Melon

Fresh-cut fruits, renowned for their convenience and nutritional value, are susceptible to rapid deterioration, compromising their quality and shelf life. In this study, a sustainable and environmentally friendly edible coating was developed based on sodium alginate (SA; 1% w/v), cedar mucilage (CM; 4% w/v), and calcium chloride (2% w/v), applied using a layer-by-layer technique to preserve the quality and prolong the shelf life of fresh-cut melon. Fruits were cut into cubes coated or uncoated by dipping and subsequently packaged in a polyethylene terephthalate container and stored for 15 days at 4 °C. Physicochemical traits and qualitative features such as polyphenol, flavonoid, carotenoid, ascorbic acid content, as well as antioxidant activity, were assessed. Furthermore, the enzymatic antioxidant system and the ascorbate–glutathione cycle were investigated. The coating reduced weight loss and enhanced polyphenol, flavonoid, and ascorbic acid content and antioxidant activity during cold storage. Edible coating (SA + CM) represents a valid tool to extend the postharvest life, improve the storability, and enhance the physicochemical and qualitative traits of fresh-cut melon. Further research is required to optimize coating formulations and application techniques to maximize their effectiveness and commercial viability in the food industry.

3D Bioprinting of Sugar Beet Pectin through Horseradish Peroxidase-Catalyzed Cross-Linking.

Horseradish peroxidase (HRP)-mediated hydrogelation, caused by the cross-linking of phenolic groups in polymers in the presence of hydrogen peroxide (H2O2), is an effective route for bioink solidification in 3D bioprinting. Sugar beet pectin (SBP) naturally has cross-linkable phenols through the enzymatic reaction. Therefore, chemical modifications are not required, unlike the various polymers that have been used in the enzymatic cross-linking system. In this study, we report the application of SBP in extrusion-based bioprinting including HRP-mediated bioink solidification. In this system, H2O2 necessary for the solidification of inks is supplied in the gas phase. Cell-laden liver lobule-like constructs could be fabricated using bioinks consisting of 10 U/mL HRP, 4.0 and 6.0 w/v% SBP, and 6.0 × 106 cells/mL human hepatoblastoma (HepG2) cells exposed to air containing 16 ppm of H2O2 concurrently during printing and 10 min postprinting. The HepG2 cells enclosed in the printed constructs maintained their viability, metabolic activity, and hepatic functions from day 1 to day 7 of the culture, which indicates the cytocompatibility of this system. Taken together, this result demonstrates the potential of SBP and HRP cross-linking systems for 3D bioprinting, which can be applied in tissue engineering applications.