MPEK: a multitask deep learning framework based on pretrained language models for enzymatic reaction kinetic parameters prediction.

Enzymatic reaction kinetics are central in analyzing enzymatic reaction mechanisms and target-enzyme optimization, and thus in biomanufacturing and other industries. The enzyme turnover number (kcat) and Michaelis constant (Km), key kinetic parameters for measuring enzyme catalytic efficiency, are crucial for analyzing enzymatic reaction mechanisms and the directed evolution of target enzymes. Experimental determination of kcat and Km is costly in terms of time, labor, and cost. To consider the intrinsic connection between kcat and Km and further improve the prediction performance, we propose a universal pretrained multitask deep learning model, MPEK, to predict these parameters simultaneously while considering pH, temperature, and organismal information. Through testing on the same kcat and Km test datasets, MPEK demonstrated superior prediction performance over the previous models. Specifically, MPEK achieved the Pearson coefficient of 0.808 for predicting kcat, improving ca. 14.6% and 7.6% compared to the DLKcat and UniKP models, and it achieved the Pearson coefficient of 0.777 for predicting Km, improving ca. 34.9% and 53.3% compared to the Kroll_model and UniKP models. More importantly, MPEK was able to reveal enzyme promiscuity and was sensitive to slight changes in the mutant enzyme sequence. In addition, in three case studies, it was shown that MPEK has the potential for assisted enzyme mining and directed evolution. To facilitate in silico evaluation of enzyme catalytic efficiency, we have established a web server implementing this model, which can be accessed at http://mathtc.nscc-tj.cn/mpek.

Mir155hg Accelerates Hippocampal Neuron Injury in Convulsive Status Epilepticus by Inhibiting Microglial Phagocytosis.

Convulsive status epilepticus (CSE) is a common critical neurological condition that can lead to irreversible hippocampal neuron damage and cognitive dysfunction. Multiple studies have demonstrated the critical roles that long non-coding RNA Mir155hg plays in a variety of diseases. However, less is known about the function and mechanism of Mir155hg in CSE. Here we investigate and elucidate the mechanism underlying the contribution of Mir155hg to CSE-induced hippocampal neuron injury. By applying high-throughput sequencing, we examined the expression of differentially expressed genes in normal and CSE rats. Subsequent RT-qPCR enabled us to measure the level of Mir155hg in rat hippocampal tissue. Targeted knockdown of Mir155hg was achieved by the AAV9 virus. Additionally, we utilized HE and Tunel staining to evaluate neuronal injury. Immunofluorescence (IF), Golgi staining, and brain path clamping were also used to detect the synaptic plasticity of hippocampal neurons. Finally, through IF staining and Sholl analysis, we assessed the degree of microglial phagocytic function. It was found that the expression of Mir155hg was elevated in CSE rats. HE and Tunel staining results showed that Mir155hg knockdown suppressed the hippocampal neuron loss and apoptosis followed CSE. IF, Golgi staining and brain path clamp data found that Mir155hg knockdown enhanced neuronal synaptic plasticity. The results from IF staining and Sholl analysis showed that Mir155hg knockdown enhanced microglial phagocytosis. Our findings suggest that Mir155hg promotes CSE-induced hippocampal neuron injury by inhibiting microglial phagocytosis.

Effects of nitrile compounds on the structure and function of soil microbial communities as revealed by metagenomes.

The proliferation of nitrile mixtures has significantly exacerbated environmental pollution. This study employed metagenomic analysis to investigate the short-term effects of nitrile mixtures on soil microbial communities and their metabolic functions. It also examined the responses of indigenous microorganisms and their functional metabolic genes across various land use types to different nitrile stressors. The nitrile compound treatments in this study resulted in an increase in the abundance of Proteobacteria, Actinobacteria, and Firmicutes, while simultaneously reducing overall microbial diversity. The key genes involved in the denitrification process, namely, nirK, nosZ, and hao, were down-regulated, and NO3--N, NO2--N, and NH4+-N concentrations decreased by 7.7%-12.3%, 11.1%-21.3%, and 11.3%-30.9%, respectively. Notably, pond sludge samples exhibited a significant increase in the abundance of nitrogen fixation-related genes nifH, vnfK, vnfH, and vnfG following exposure to nitrile compounds. Furthermore, the fumarase gene fumD, which is responsible for catalyzing fumaric acid into malic acid in the tricarboxylic acid cycle, showed a substantial increase of 7.2-10.6-fold upon nitrile addition. Enzyme genes associated with the catechol pathway, including benB-xylY, dmpB, dmpC, dmpH, and mhpD, displayed increased abundance, whereas genes related to the benzoyl-coenzyme A pathway, such as bcrA, dch, had, oah, and gcdA, were notably reduced. In summary, complex nitrile compounds were found to significantly reduce the species diversity of soil microorganisms. Nitrile-tolerant microorganisms demonstrated the ability to degrade and adapt to nitrile pollutants by enhancing functional enzymes involved in the catechol pathway and fenugreek conversion pathway. This study offers insights into the specific responses of microorganisms to compound nitrile contamination, as well as valuable information for screening nitrile-degrading microorganisms and identifying nitrile metabolic enzymes.

Identification of a (+)-cubenene synthase from filamentous fungi Acremonium chrysogenum.

Sesquiterpene synthases convert farnesyl diphosphate into various sesquiterpenes, which find wide applications in the food, cosmetics and pharmaceutical industries. Although numerous putative sesquiterpene synthases have been identified in fungal genomes, many lack biochemical characterization. In this study, we identified a putative terpene synthase AcTPS3 from Acremonium chrysogenum. Through sequence analysis and in vitro enzyme assay, AcTPS3 was identified as a sesquiterpene synthase. To obtain sufficient product for NMR testing, a metabolic engineered Saccharomyces cerevisiae was constructed to overproduce the product of AcTPS3. The major product of AcTPS3 was identified as (+)-cubenene (55.46%) by GC-MS and NMR. Thus, AcTPS3 was confirmed as (+)-cubenene synthase, which is the first report of (+)-cubenene synthase. The optimized S. cerevisiae strain achieved a biosynthesis titer of 597.3 mg/L, the highest reported for (+)-cubenene synthesis.

Highly Flexible K-Intercalated MnO2 /Carbon Membrane for High-Performance Aqueous Zinc-Ion Battery Cathode.

The layered MnO2 is intensively investigated as one of the most promising cathode materials for aqueous zinc-ion batteries (AZIBs), but its commercialization is severely impeded by the challenging issues of the inferior intrinsic electronic conductivity and undesirable structural stability during the charge-discharge cycles. Herein, the lab-prepared flexible carbon membrane with highly electrical conductivity is first used as the matrix to generate ultrathin δ-MnO2 with an enlarged interlayer spacing induced by the K+ -intercalation to potentially alleviate the structural damage caused by H+ /Zn2+ co-intercalation, resulting in a high reversible capacity of 190 mAh g-1 at 3 A g-1 over 1000 cycles. The in situ/ex-situ characterizations and electrochemical analysis confirm that the enlarged interlayer spacing can provide free space for the reversible deintercalation/intercalation of H+ /Zn2+ in the structure of δ-MnO2 , and H+ /Zn2+ co-intercalation mechanism contributes to the enhanced charge storage in the layered K+ -intercalated δ-MnO2 . This work provides a plausible way to construct a flexible carbon membrane-based cathode for high-performance AZIBs.

Comparison of pulsed-field gel electrophoresis and a novel amplified intergenic locus polymorphism method for molecular typing of Campylobacter jejuni.

Campylobacter is regarded as the leading cause of zoonotic diseases and Campylobacter jejuni (C. jejuni) is one of the predominant pathogenic species. To track C. jejuni infections, various genotyping methods have been used. In this study, amplified intergenic locus polymorphism (AILP) was used to type C. jejuni for the first time. To confirm its feasibility, pulsed-field gel electrophoresis (PFGE) was performed as a control, and the results obtained by the AILP and PFGE methods were compared. Fifty-one isolates were resolved into 34 and 29 different genotypes with Simpson's indices of 0.976 and 0.967 using the AILP and PFGE methods, respectively. The adjusted Rand coefficient of the two approaches was as high as 0.845. In summary, the data showed that the two genotyping methods were similar for discriminating isolates and were both appropriate methods to distinguish whether two isolates were indistinguishable, but the AILP was faster and less costly than PFGE. Therefore, the AILP is a reliable, rapid, and highly discriminative method to genotype C. jejuni collected from poultry meat, which is helpful to effectively monitor C. jejuni.

HELQ suppresses migration and proliferation of non-small cell lung cancer cells by repairing DNA damage and inducing necrosis.

HELQ plays a key role in DNA damage response and cell-cycle checkpoint regulation. It has been implicated in ovarian and pituitary tumors and may play a role in germ cell maintenance. This study investigated the role of HELQ in lung cancer. The expression of HELQ in patients with non-small-cell lung cancer (NSCLC) was downregulated compared with normal human lungs. Clinical prognostic analysis of Kaplan-Meier plots revealed that patients with NSCLC with low HELQ levels had a reduced overall survival. Further, we found that HELQ depletion enhanced lung cancer cell malignancy. Furthermore, overexpression of HELQ in lung cancer cells reduced cell migration in vitro, while DNA damage repair was inhibited. Both in vitro and in vivo studies have shown that HELQ induces cell death. Mechanistically, we found that cells overexpressing HELQ showed a tendency to induce necrosis. After analyzing the database of HELQ interactors. we found that RIPK3 may interact with it and proved this conclusion by immunoprecipitation. Our findings identified the tumor suppressive role of HELQ in malignant human lung cancer and unraveled a potential therapeutic strategy for cancer treatment through HELQ activation. Moreover, HELQ may also be a predictive biomarker for the clinical predisposition, progression, and prognosis of lung cancer.

Phenotypic drug susceptibility characterization and clinical outcomes of tuberculosis strains with A-probe mutation by GeneXpert MTB/RIF.

BACKGROUND: GeneXpert MTB/RIF (Xpert) assay was applied widely to detect Mycobacterium tuberculosis (MTB) and rifampicin resistance. METHODS: Retrospectively investigated the association among treatment histories, phenotypic drug susceptibility testing (pDST) results, and clinical outcomes of patients infected with probe A absent mutation isolate confirmed by Xpert. RESULTS: 63 patients with only probe A absent mutation and 40 with additional pDST results were analyzed. 24 (60.0%) patients had molecular-phenotypic discordant rifampicin (RIF) susceptibility testing results, including 12 (12/13, 92.3%) new tuberculosis (TB) patients and 12 (12/27, 44.4%) retreated ones. 28 (28/39, 71.8%) retreated patients received first-line treatment regime within two years with failed outcomes. New patients had better treatment outcomes than retreated ones (successful: 83.3% VS. 53.8%; P value = 0.02). The clinical results of RIF-susceptible TB confirmed by pDST were not better than RIF-resistant TB (successful: 62.5% VS. 50.0%; P value = 0.43). INH-resistant TB and INH-susceptible TB had similar treatment outcomes too (successful: 61.5% VS. 50.0%; P value = 0.48). 11 (11/12, 91.7%) new patients treated with the short treatment regimen (STR) had successful outcomes. CONCLUSIONS: More than half of mono probe A absent isolates had RIF molecular-phenotypic discordance results, especially in new patients. Probe A mutations were significantly associated with unsuccessful clinical outcomes, whether the pDST results were RIF susceptible or not. STR was the best choice for new patients. TRIAL REGISTRATION: retrospectively registered in Wuhan Jinyintan Hospital (No. 2021-KY-16).

Rapid Genotyping of Campylobacter coli Strains from Poultry Meat by PFGE, Sau-PCR, and fla-DGGE.

The genotyping of Campylobacter coli was done using three methods, pulsed-field gel electrophoresis (PFGE), Sau-polymerase chain reaction (Sau-PCR), and denaturing gradient gel electrophoresis assay of flagellin gene (fla-DGGE) and the characteristics of these assays were compared. The results showed that a total of 53 strains of C. coli were isolated from chicken and duck samples in three markets. All isolates were clustered into 31, 33, and 15 different patterns with Simpson's index of diversity (SID) values of 0.972, 0.974, and 0.919, respectively. Sau-PCR assay was simpler, more rapid, and had higher discriminatory power than PFGE assay. Fla-DGGE assay could detect and illustrate the number of contamination types of C. jejuni and C. coli without cultivation, which saved more time and cost than Sau-PCR and PFGE assays. Therefore, Sau-PCR and fla-DGGE assays are both rapid, economical, and easy to perform, which have the potential to be promising and accessible for primary laboratories in genotyping C. coli strains.

Intelligent Protein Design and Molecular Characterization Techniques: A Comprehensive Review.

In recent years, the widespread application of artificial intelligence algorithms in protein structure, function prediction, and de novo protein design has significantly accelerated the process of intelligent protein design and led to many noteworthy achievements. This advancement in protein intelligent design holds great potential to accelerate the development of new drugs, enhance the efficiency of biocatalysts, and even create entirely new biomaterials. Protein characterization is the key to the performance of intelligent protein design. However, there is no consensus on the most suitable characterization method for intelligent protein design tasks. This review describes the methods, characteristics, and representative applications of traditional descriptors, sequence-based and structure-based protein characterization. It discusses their advantages, disadvantages, and scope of application. It is hoped that this could help researchers to better understand the limitations and application scenarios of these methods, and provide valuable references for choosing appropriate protein characterization techniques for related research in the field, so as to better carry out protein research.

Identification of the sesquiterpene synthase AcTPS1 and high production of (-)-germacrene D in metabolically engineered Saccharomyces cerevisiae.

BACKGROUND: The sesquiterpene germacrene D is a highly promising product due to its wide variety of insecticidal activities and ability to serve as a precursor for many other sesquiterpenes. Biosynthesis of high value compounds through genome mining for synthases and metabolic engineering of microbial factories, especially Saccharomyces cerevisiae, has been proven to be an effective strategy. However, there have been no studies on the de novo synthesis of germacrene D from carbon sources in microbes. Hence, the construction of the S. cerevisiae cell factory to achieve high production of germacrene D is highly desirable. RESULTS: We identified five putative sesquiterpene synthases (AcTPS1 to AcTPS5) from Acremonium chrysogenum and the major product of AcTPS1 characterized by in vivo, in vitro reaction and NMR detection was revealed to be (-)-germacrene D. After systematically comparing twenty-one germacrene D synthases, AcTPS1 was found to generate the highest amount of (-)-germacrene D and was integrated into the terpene precursor-enhancing yeast strain, achieving 376.2 mg/L of (-)-germacrene D. Iterative engineering was performed to improve the production of (-)-germacrene D, including increasing the copy numbers of AcTPS1, tHMG1 and ERG20, and downregulating or knocking out other inhibitory factors (such as erg9, rox1, dpp1). Finally, the optimal strain LSc81 achieved 1.94 g/L (-)-germacrene D in shake-flask fermentation and 7.9 g/L (-)-germacrene D in a 5-L bioreactor, which is the highest reported (-)-germacrene D titer achieved to date. CONCLUSION: We successfully achieved high production of (-)-germacrene D in S. cerevisiae through terpene synthase mining and metabolic engineering, providing an impressive example of microbial overproduction of high-value compounds.

Surface Reconstruction of Co4N Coupled with CeO2 toward Enhanced Alkaline Oxygen Evolution Reaction.

Constructing the active interface in a heterojunction electrocatalyst is critical for the electron transfer and intermediate adsorption (O*, OH*, and HOO*) in alkaline oxygen evolution reaction (OER) but still remains challenging. Herein, a CeO2/Co4N heterostructure is rationally synthesized through the direct calcination of Ce[Co(CN)6], followed by thermal nitridation. The in situ electrochemically generated CoOOH on the surface of Co4N serves as the active site for the OER, and the coupled CeO2 with oxygen vacancy can optimize the energy barrier of intermediate reactions of the OER, which simultaneously boosts the OER performance. Besides, electrochemical measurement results demonstrate that oxygen vacancies in CeO2 and optimized absorption free energy originating from the electron transfer between CeO2 and CoOOH contribute to enhanced OER kinetics. This work provides new insight into regulating the interface heterostructure to rationally design efficient OER electrocatalysts under alkaline conditions.

Computational design of a polymorph for 2D III-V orthorhombic monolayers by first principles calculations: excellent anisotropic, electronic and optical properties.

Using first principles calculations, we have designed a new polymorph for two-dimensional (2D) III-V group materials with an orthorhombic phase, including BN, BP, BAs, AlN, AlP, and GaN, and investigated their structural, electronic, and optical properties. The phonon dispersion calculations have shown that BN, BP, AlN, and GaN possess excellent dynamic stabilities. The 2D BN is a direct semiconductor, and its bandgap predicted by PBE and HSE calculations is 0.76 and 1.73 eV, respectively. The calculated mobilities of the BN, AlN, and GaN monolayers have shown their high conductivities, and the monolayered AlN and GaN possess strong anisotropic carrier transport characters. The 2D AlN and AlP and GaN monolayers are found to be indirect semiconductors with bandgaps in the range of 0.66-1.65 eV. The 2D BN and BP monolayers exhibit extremely high and anisotropic absorbance, and their absorption energy range covers the whole solar spectrum, rendering them potential candidates for applications in solar cells. More importantly, their optical properties are shown to have highly anisotropic optical absorbance, making them promising candidates for manufacturing anisotropic optoelectronic devices. Our computational study not only provides a new class of 2D materials to enrich the material genome database, but also paves the way for practical applications of 2D III-V materials for electronic and optoelectronic devices.

Synergistic Tuning of the Electronic Structure of Mo2C by P and Ni Codoping for Optimizing Electrocatalytic Hydrogen Evolution.

Developing earth-abundant and highly efficient nonprecious metal catalysts for hydrogen evolution reaction (HER) is critical for the storage and conversion of renewable energy sources. Molybdenum carbide (Mo2C) has been extensively investigated as one of the most promising nonprecious electrocatalysts for boosting HER because of its low cost, high electrical conductivity, good chemical structure, and similar electronic structure to that of Pt. However, Mo2C always exhibits the negative hydrogen-binding energy, which can largely prevent adsorbed H desorption during the HER process. Herein, we report P- and Ni-dual-doped Mo2C in porous nitrogen-doped carbon (P/Ni-Mo2C) as an electrocatalyst for the HER, exhibiting excellent activity and durability with a low overpotential of 165 mV at 10 mA cm-2 in alkaline electrolyte. Density functional theory (DFT) calculations proved that P and Ni acted as the anion and cation, respectively, to synergistically tune the electronic properties of Mo2C to decrease the negative hydrogen-binding energy, endowing the catalyst with excellent catalytic performance for the HER.

Synovial and pulmonary dysfunctions are induced by crosstalk of Smad and Erk pathways in an arthritis model.

In the current experiment, the effects of transforming growth factor (TGF)-ß1/Smad and ERK pathway crosstalk on synovial and pulmonary systems during rheumatoid arthritis have been investigated. For this purpose, rats were divided into normal control (NC) and model control (MC) groups. In the MC group, 0.1 ml Freund's complete adjuvant was injected intradermally into the right hind paw, and the resulting inflammation represented a rheumatoid arthritis model. Joint swelling and changes in lung functions were observed in arthritic rats. Synovial and lung were observed by light and electron microscopies. Enzyme-linked immunosorbent assays were used to detect TGF-ß1, interleukin (IL)-1ß, IL-4, IL-10, interferon-γ (IFN-γ), connective tissue growth factor (CTGF), and fibroblast growth factor (FGF). PCR, immunohistochemistry, and immunoblotting were used to detect changes in Smad and ERK pathways of synovial and lung tissues. Compared with the NC group, toe swelling was elevated in the MC group. Pulmonary functions FEV1, FEF50, FEF75, MMF, and PEF were decreased (P< 0.01). Serum cytokines IL-1ß, IL-4, TGF-ß1, and CTGF were increased, while IFN-γ, IL-10, Th1/Th2 cell ratio, and FGF were decreased (P< 0.01 or P< 0.05). Expression of TGF-ß1 and Smad2/3/4 mRNAs and TGF-ß1, TßRI, TßRII, Smad2/3, p-Smad2/3, and Smad4 proteins in the synovial membrane and lung tissue were increased, and expression of Smad7 mRNA and protein was decreased (P<0.01) or P<0.05). Expression of ERK2 mRNA and p-ERK1/2 protein was increased in the synovial membrane and lung tissue, and expression of ERK1/2 mRNAs and ERK1/2 and p-ERK1/2 proteins was increased in lung tissue (P< 0.01 or P< 0.05). Correlation analysis showed that FEV1 was negatively correlated with TGF-ß1 mRNA and protein in arthritic rats, FEF25 was negatively correlated with Smad4 protein, and FEF50 was negatively correlated with the TßRII protein, and FEF75, TGF-ß1 and Smad3 mRNAs. There was a negative correlation between Smad2/3 protein and a negative correlation between PEF and TGF-ß1 protein (P< 0.05). FEF50 and MMF were positively correlated with Smad7 mRNA (P< 0.05). FEV1 was negatively correlated with ERK2 mRNA, and FEF25 was negatively correlated with p-ERK1/2 protein. FEF75 and MMF were negatively correlated with ERK1/2 and p-ERK1/2, respectively (P< 0.05). ERK1 mRNA was positively correlated with Smad3 mRNA and TßRII protein, ERK2 mRNA was positively correlated with p-Smad2/3, and ERK1/2 protein was positively correlated with Smad2 mRNA, Smad4 protein, p-ERK1/2 protein, Smad4 mRNA, and p-Smad2/3 protein (P< 0.05). p-ERK1/2 protein was negatively correlated with Smad7 protein (P< 0.05). It is concluded that arthritic rats have synovial and systemic pulmonary damage. Smad and ERK pathway crosstalk leads to systemic lesions. Smad and ERK pathways are gradually activated by phosphorylation under the induction of the TGF-ß1 promoter, and then participate in transcriptional activities, leading to the increase in synovial inflammation of arthritis, pulmonary lesions, and decreases in lung functions.

Resveratrol protects the mitochondria from vitrification injury in mouse 2-cell embryos.

Mitochondria play a key role in embryo development by providing energy. However, vitrification often causes mitochondrion damage of embryo, which further impairs embryo development. Therefore, the efficiency of embryo development after vitrification could be improved by protecting mitochondrial function from vitrification injury. The purpose of this study was to investigate the effects of resveratrol on mitochondrial damage after vitrification. The results showed that vitrification induced the abnormal mitochondrial distribution and damage mitochondrial function of mouse 2-cell embryos. However, co-culturing with resveratrol for 2 h could repair the abnormal mitochondrial distribution and mitochondrial dysfunction of embryos after vitrification. More than anything, the subsequent development ability of vitrified-thawed 2-cell embryos was significantly higher than that with no resveratrol treatment. In conclusion, resveratrol could protect the mitochondrial from injury caused by vitrification.

Structural and Functional Characterization of Conotoxins from Conus achatinus Targeting NMDAR.

Conotoxin-Ac1 and its variant conotoxin-Ac1-O6P, were isolated from the venom duct of Conus achatinus, a fish-hunting cone snail species collected in the Sea of Hainan, China. Conotoxin-Ac1 is linear peptide that contain 15 amino acids. In the present study, we synthesized and structurally and functionally characterized conotoxin-Ac1 as well as 19 variants. Electrophysiological results showed that conotoxin-Ac1 inhibited N-methyl-D-aspartate receptor subunit 2B (NR2B) with an IC50 of 8.22 ± 0.022 µM. Further structure-activity studies of conotoxin-Ac demonstrated that polar amino acid residues were important for modulating its active, and the replacement of N1, O9, E10, and S12 by Ala resulted in a significant decrease in potency to NR2B. °Furthermore, conotoxin-Ac1 and conotoxin-Ac1-O6P were tested in hot-plate and tail-flick assays to measure the potential analgesic activity to an acute thermal stimulus in a dose-dependent manner. Subsequently, the analgesic activity of conotoxin-Ac1 mutants was analyzed by the hot-plate method. The results show that N1, Y2, Y3, E10, N11, S12, and T15 play an important role in the analgesic activity of conotoxin-Ac1. N1 and S12 have significant effects on conotoxin-Ac1 in inhibiting NR2B and analgesic activity. In conclusion, we have discovered that conotoxin-Ac1 is an inhibitor of NMDAR and displays antinociceptive activity.

Research Progress in the Biosynthetic Mechanisms of Marine Polyether Toxins.

Marine polyether toxins, mainly produced by marine dinoflagellates, are novel, complex, and diverse natural products with extensive toxicological and pharmacological effects. Owing to their harmful effects during outbreaks of marine red tides, as well as their potential value for the development of new drugs, marine polyether toxins have been extensively studied, in terms of toxicology, pharmacology, detection, and analysis, structural identification, as well as their biosynthetic mechanisms. Although the biosynthetic mechanisms of marine polyether toxins are still unclear, certain progress has been made. In this review, research progress and current knowledge on the biosynthetic mechanisms of polyether toxins are summarized, including the mechanisms of carbon skeleton deletion, pendant alkylation, and polyether ring formation, along with providing a summary of mined biosynthesis-related genes. Finally, future research directions and applications of marine polyether toxins are discussed.

High-Throughput Identification and Analysis of Novel Conotoxins from Three Vermivorous Cone Snails by Transcriptome Sequencing.

The venom of each Conus species consists of a diverse array of neurophysiologically active peptides, which are mostly unique to the examined species. In this study, we performed high-throughput transcriptome sequencing to extract and analyze putative conotoxin transcripts from the venom ducts of 3 vermivorous cone snails (C. caracteristicus, C. generalis, and C. quercinus), which are resident in offshore waters of the South China Sea. In total, 118, 61, and 48 putative conotoxins (across 22 superfamilies) were identified from the 3 Conus species, respectively; most of them are novel, and some possess new cysteine patterns. Interestingly, a series of 45 unassigned conotoxins presented with a new framework of C-C-C-C-C-C, and their mature regions were sufficiently distinct from any other known conotoxins, most likely representing a new superfamily. O- and M-superfamily conotoxins were the most abundant in transcript number and transcription level, suggesting their critical roles in the venom functions of these vermivorous cone snails. In addition, we identified numerous functional proteins with potential involvement in the biosynthesis, modification, and delivery process of conotoxins, which may shed light on the fundamental mechanisms for the generation of these important conotoxins within the venom duct of cone snails.

Beta transmutations in apatites with ferric iron as an electron acceptor - implication for nuclear waste form development.

Apatite-structured materials have been considered for the immobilization of a number of fission products from reprocessing nuclear fuel because of their chemical durability as well as compositional and structural flexibility. It is hypothesized that the effect of beta decay on the stability can be mitigated by introducing an appropriate electron acceptor at the neighboring sites in the structure. The decay series 137Cs → 137Ba and 90Sr → 90Y → 90Zr were investigated using a spin-polarized DFT approach to test the hypothesis. Apatites with compositions of Ca10(PO4)6F2 and Ca4Y6(SiO4)6F2 were selected as model systems for the incorporation of radionuclides Cs and Sr, respectively. Ferric iron was introduced in the structure as an electron acceptor. Electron density of states, crystal and defect structures, and energies before and after beta decay were calculated. The calculated electron density of states suggests that the extra electron is localized at the ferric iron, which changes its oxidation state and becomes ferrous iron. The crystal and defect structures were analyzed based on the volume, lattice parameters, radial distribution functions, metal cation to coordinating oxygen distances, and the metaprism twist angle of the apatite crystal structure. The results show that there are minor changes in the crystal and defect structures of CsFeCa8(PO4)6F2 with Cs+ and Fe3+ substitutions undergoing the Cs → Ba transmutation, and of Ca3SrY4Fe2(SiO4)6F2 with Sr2+ and Fe3+ substitutions undergoing the Sr → Y → Zr transmutations. The last decay change, from Y3+ → Zr4+, causes relatively larger changes in the local defect structure around Zr involving the coordination environment but the change is not significant to the crystal structure. The results on calculated cohesive energy suggest that the transmutations Cs+ → Ba2+ and Sr2+ → Y3+ → Zr4+ in both apatite compositions are energetically favorable, which is consistent with the minor structure distortions. Increased stability with favorable energetics and structural distortion by incorporating ferric ion is significant with respect without variable valence ions. The results confirm the structural and compositional adaptability of apatites upon beta transmutations. The study suggests that apatite-structured materials could be promising nuclear waste forms to mitigate the beta decay induced instability, by incorporating variable valence cations such as ferric iron in the structure. The study demonstrates a methodology which evaluates the structural stability of waste forms incorporating fission products undergoing beta decay.