High Molecular Diversity Research Articles

Base-Mediated Annulation of ortho-Iminophenols and ortho-Vinylphenols with MBH Carbonates of Isatins: Straightforward Access to Dihydrobenzofuran and Benzofuran Derivatives.

We have developed a convenient synthetic protocol for efficient construction of significant dihydrobenzofuran and benzofuran scaffolds by Lewis base-mediated annulation reaction ortho-iminophenols and ortho-vinylphenols with MBH carbonates of isatins under mild and metal-free conditions. The selective generation of different kinds of dihydrobenzofuran and benzofuran derivatives was successfully achieved by employing different substituted isatin-derived MBH carbonates with ortho-N-tosyliminophenols and ortho-vinylphenols. The features included broad substrate scopes, excellent functional group compatibility, high molecular diversity, and atomic economy.

Impact of environmental conditions on organic matter in astrophysical ice analogues

ABSTRACT The existence of organic matter presenting a high molecular diversity in extraterrestrial environments is well documented. To understand the origin of this organic diversity, laboratory experiments were developed and showed that irradiation and thermal alteration of simple molecules such as methanol, water, and ammonia in conditions mimicking astrophysical ice environments. Ices containing water, methanol, and ammonia (H2O: MeOH: NH3) photolyzed and monitored by infrared spectroscopy, while the organic matter formed at room temperature was analyzed in situ with infrared spectroscopy and ex situ with high-resolution mass spectrometry. Those ices irradiated at 77 K and 10−8 mbar shows a significant organic molecular diversity: residual organic compounds contain up to 78 C, 188 H, 123 N, and 37 O. Most of them contains all four CHNO atoms (76–86 per cent), followed by CHO (11–17 per cent), and CHN compounds (5–6 per cent). CHNO and CHO compounds are more aliphatic (34–53 per cent), while CHN compounds are mostly condensed aromatics (83–90 per cent). In this work, our objective is to investigate impacts of environment on this organic molecular diversity by focusing on three parameters: photon dose, pressure, and heating rate during the warming process. Analyses of the residue formed showed that the heating rate and pressure weakly alter the abundance of the final organic material, while the irradiation rate reduced its abundance at high photon doses by a factor of 8. These results give insights on the impact of icy environment conditions in the evolution of astrophysical organic matter.

Harmonized coexistence of intragenomic variations in diatom Skeletonema strains

Metabarcoding analysis has been demonstrated to be an effective technology for monitoring diversity and dynamics of phytoplankton including Skeletonema species. Although molecular diversity uncovered in metabarcoding projects has generally been interpreted as sum of interspecies diversity and intraspecies diversity, accumulating evidence suggests that it also harbors unprecedentedly high levels of intra-genomic variations (IGVs). As up to thousands of amplicon sequence variants (ASVs) identified in a typical metabarcoding project can be annotated to be Skeletonema species, we hypothesize that substantial portions of these ASVs are contributed by IGVs. Here, the nature of IGVs in Skeletonema species was quantitatively analyzed by carrying out single-strain metabarcoding analysis of 18S rDNA V4 in 49 strains belonging to seven Skeletonema species. Results showed that each Skeletonema strain harbored a high level of IGVs as expected. While many Skeletonema strains each contained one dominant ASV and a substantial number of ASVs displaying much lower relative abundance, other Skeletonema strains each contained multiple ASVs with comparable or nearly equally abundances. Thus the co-existence of multiple dominant ASVs in a single cell indicated a tug-of-war of these variants in evolution, which may eventually result in harmonized coexistence of multiple dominant ASVs. A total of nine dominant ASVs and 652 non-dominant ASVs were found in 49 strains of seven Skeletonema species, indicating rich interspecies and intraspecies variations, and complex evolution of IGVs in genus of Skeletonema. The results confirmed that the extensive degree of IGVs was the main contributor to the high molecular diversity revealed by metabarcoding analysis. This study highlights the importance of quantitative characterization of IGVs in Skeletonema species for accurate interpretation of species diversity in metabarcoding analysis.

Sporocysts of Sarcocystis bertrami (syn. Sarcocystis fayeri) shed by dogs: Molecular analysis, morphometry and pattern of excretion

Sarcocystis bertrami (synonym: Sarcocystis fayeri) is a coccidian parasite that infects horses and donkeys in several countries. Dogs are known as definitive hosts of the parasite, however, the patent period is not well defined, and S. bertrami shed by dogs has never been confirmed by molecular methods. Here we investigated the shedding of S. bertrami by experimentally infected dogs and examined the excreted parasites by morphological and molecular tools. Three dogs of small breeds (one Yorkshire terrier and two miniature Pinschers) were acquired with ages of 30 and 60 days and were exclusively fed commercial dog food. Two dogs consumed equine muscle tissues containing cysts of S. bertrami. The third dog served as negative control and was simultaneously fed commercial dog food. The two animals that received equine tissues shed sporocysts and/or oocysts in their feces after prepatent periods of 13 and 23 days. The patent periods were 47 and 14 days. Sporocysts showed average dimensions of 14.19 µm (± 0.53) x 10.06 µm (± 0.44). The control dog did not shed sporocysts or oocysts of the parasite. Interestingly, patent periods had never been reported, and for one dog, the patent period (47 days) was longer than that reported for other Sarcocystidae parasites. PCRs to the gene 18S and to the internal transcribed spacer 1 (ITS1) of the rDNA were successfully performed with DNA extracted from sporocysts. ITS1 sequences were also obtained from the equine tissue cysts used to infect the dogs. Nucleotide sequences of cloned fragments of 18S from sporocysts, and ITS1 from both stages (tissue cysts and sporocysts) matched with S. bertrami (18S: 97.50–99.88 %; ITS1: 88.76–95.21 %), although high molecular diversity was observed with data from these loci. PCR to cox1 using sporocysts’ DNA failed to amplify any product. The possibility of the existence of an additional and undescribed Sarcocystis species in the excreted sporocysts, besides S. bertrami, cannot be excluded from this experiment. To our knowledge, this is the first molecular confirmation of S. bertrami in canine feces. Sporocyst dimensions and prepatent periods observed in this study were similar to those previously described for S. bertrami and S. fayeri. In conclusion, the molecular, morphological and biological data generated here fit in previous descriptions for both S. bertrami and S. fayeri.

Design and evaluation of novel inhibitors for the treatment of clear cell renal cell carcinoma

The efficacy of conventional chemotherapies in treating clear cell renal cell carcinoma (ccRCC) is often limited due to its high molecular diversity, generally low response rates to standard treatments, and prevalent drug resistance. Recent advancements in the molecular understanding of ccRCC, alongside the discovery of novel therapeutic agents targeting specific proteins, have significantly altered the treatment landscape for ccRCC. Here, we synthesized 27 new compounds that are derivatives of TG-101209 to modulate BUB1B (BUB1 mitotic checkpoint serine/threonine kinase B). BUB1B has been recently identified as a drug target for the development of effective ccRCC treatment based on global transcriptomics profiling of ccRCC tumours and gene co-expression network analysis. We characterized the molecular structures of these 27 compounds by 1H and 13C NMR and Mass spectrometry. We evaluated the effect of these 27 compounds by analysing the modulation of the BUB1B expression. Our primary objective was to design and assess the efficacy of these new compounds in reducing the viability of Caki-1 cells, a ccRCC cell line. We performed the computational docking studies by the Schrödinger Maestro software and demonstrated that three of these compounds (13a, 5i, and 5j) effectively downregulated BUB1B expression and eventually triggered necrosis and apoptosis in the Caki-1 cell line based on the structure–activity relationship (SAR) analysis. The IC50 values for compounds 13a, 5i, and 5j were calculated as 2.047 µM, 10.046 µM, and 6.985 µM, respectively, indicating their potent inhibitory effects on cell viability. Our study suggests that these compounds targeting BUB1B could offer a more effective and promising approach for ccRCC treatment compared to the conventionally used tyrosine kinase inhibitors. Our study underscores the potential of leveraging targeted therapies against specific molecular pathways in ccRCC may open new avenues for the development of effective treatment strategies against ccRCC.

Salix species and varieties affect the molecular composition and diversity of soil organic matter

Abstract Background and aims Most studies of the relationships between the composition of soil organic matter and plant cover have been carried out at the plant genera level. However, they have largely overlooked the potential effects that plant varieties, belonging to the same genus, can have on soil organic matter. Methods We investigated whether plant varieties belonging to different Salix species (S. dasyclados and S. viminalis) impacted the composition of organic matter using mid-infrared spectroscopy and pyrolysis GC/MS. Top-soils were taken from an 18 year-old long-term field trial where six Salix varieties were grown as short-rotation coppice under two fertilisation regimes. Results Significant differences in the molecular composition and diversity of the soil organic matter were observed in the fertilised plots. The effects were mostly visible at the species level, i.e. the organic matter in soil under S. dasyclados varieties had higher molecular diversity and lignin content than under S. viminalis, potentially due to differences in the amount and composition of their litter inputs. Smaller differences among varieties from the same species were also observed. No significant effects of Salix varieties were observed in the unfertilised plots. The relatively high degree of spatial variability of several soil properties found in these plots may have masked plant variety and/or species effects. Conclusion This study provides evidence that the identity of Salix species or varieties can affect the molecular composition and diversity of soil organic matter. The corresponding traits should be considered in breeding programmes to enhance soil organic C accumulation and persistence.

An integrative approach highlights the discrepancy in the genetic, phenotypic, and presumptive taxonomic structure of Phoxinus (Actinopterygii, Leuciscidae, Phoxininae) in Bulgaria.

The present drainage network of Bulgaria is the result of a complex Neogene and Quaternary evolution. Karst, which has developed on 23% of the territory, further complicates the hydrological pattern. Fresh waters of Bulgaria drain into the Black Sea and the Aegean Sea basins and can be roughly divided into the Danube (Middle and Lower Danube), non-Danube Black Sea, East Aegean, and West Aegean hydrological regions. Phoxinus, a small leuciscid fish, has a mosaic distribution in all four of these regions, inhabiting small mountainous and semi-mountainous streams. Based on morphology, it was identified as three species, Phoxinus phoxinus in the Danube, Phoxinus strandjae in the non-Danube, and Phoxinus strymonicus in West Aegean region. Later, molecular data revealed Phoxinus csikii and Phoxinus lumaireul in the Middle Danube and P. csikii in the Lower Danube. Phoxinus has been the focus of many studies, showing a high molecular and morphological diversity, which is not entirely consistent with previous morphology-only-based taxonomic concepts. In this study, molecular (a mitochondrial marker and a nuclear marker) and morphological data from both historical and recently sampled collections were analysed to assess the applicability of the integrative approach in Phoxinus. The results showed a significant influence of the complex paleo- and recent hydrology on the currently observed genetic structure of the considered populations and species. Furthermore, the study also demonstrated a strong influence of phenotypic plasticity on the morphological analysis of Phoxinus and the lack of a clear differentiation between P. csikii and P. strandjae. A barcoded specimen was designated as neotype to fix the species named P. strandjae in the current taxonomic concept. Finally, a significant discordance between genetically delimited clades and phenotypic groups did not allow a proper delineation of the species distributed in Bulgaria, demonstrating that more molecular markers are needed for further taxonomic study of the Phoxinus complex.

Streptococcus equi subsp. zooepidemicus: High molecular diversity of Argentinian strains isolated from mares with endometritis

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a mucosal commensal of the lower genital tract in horses and is the most isolated bacterium causing endometritis in mares. The aim of this study was to determine the molecular diversity of S. zooepidemicus obtained from endometritis in mares in Buenos Aires province, Argentina. Thirty isolates obtained from the uterus of mares in 2005 and 2017 were studied. The MLST scheme was applied to identify the Argentinian genotypes and the clonal relationships and patterns of evolutionary descent were identified using the eBURST algorithm – goeBURST. Twenty six different Sequence types (STs) were identified, being only 11 of them previously reported in horses and also, from several host species and tissues. The other 15 STs were reported in Argentinian reproductive strains of mares in our study for the first time. The genotypes obtained from uterus in Argentina were not evenly distributed when all the published S. zooepidemicus STs were analysed, thus, it was not possible to establish that the same lineage circulates in our equine population. The fact that the identified genotypes were also reported in other countries, diverse samples and host species suggest that there is not a host, and an anatomical niche adaptation. Finally, the isolation of the same genotype in the vagina/clitoris and the uterus of the same mare highlights the versatility of S. zooepidemicus and its role as an opportunistic pathogen.

Mycorrhizal status of Guarianthe skinneri (Orchidaceae) in urban trees in Tapachula, Chiapas, Mexico

Objective: To isolate and classify morphologically and molecularly mycorrhizal fungi associated with adult plants of Guarianthe skinneri (Bateman) Dressler & W.E. Higgins (Orchidaceae), distributed in different phorophytes, exotic and native trees, in the City of Tapachula, Chiapas, Mexico. Design/Methodology/Approach: We sampled roots from adult plants growing in two native phorophytes, Byrsonima crassifolia (L.) KUNTH and Tabebuia rosea (BERTOL.) BERTERO EX A. DC. and two exotic phorophytes, Terminalia catappa L. and Ficus benjamina L. located in the city's road. By the isolation of mycorrhizal strains, we had diagnosed them by morpho-physiological attributes, and molecularly (Sanger sequencing of the ITS1-4 region). Results: Forty-three fungal strains of two anamorphic mycorrhizal genus Epulorhiza and Ceratorhiza were obtained: 50% of the isolates came from plants growing in the exotic tree T. catappa with undigested pelotons and the highest molecular diversity (three contigs of the genus Tulasnella). Ficus benjamina had one molecular species shared with the native B. crassifolia. Roots growing in the native T. rosea tree, even though few isolates could be purified. Study Limitations/Implications: Even if the research was exploratory, it was possible to highlight the diverse mycorrhizal partners that urban phorophytes of G. skinneri harbor, showing their potential in the ex situ conservation of this species. Findings/Conclusions: The large number of the anamorph Epulorhiza isolates obtained from all phorophytes, reinforces previous observations suggesting that candelaria is preferentially associated with species of the Family Tulasnellaceae.

Discovery and SAR Study of Boronic Acid-Based Selective PDE3B Inhibitors from a Novel DNA-Encoded Library.

Human genetic evidence shows that PDE3B is associated with metabolic and dyslipidemia phenotypes. A number of PDE3 family selective inhibitors have been approved by the FDA for various indications; however, given the undesirable proarrhythmic effects in the heart, selectivity for PDE3B inhibition over closely related family members (such as PDE3A; 48% identity) is a critical consideration for development of PDE3B therapeutics. Selectivity for PDE3B over PDE3A may be achieved in a variety of ways, including properties intrinsic to the compound or tissue-selective targeting. The high (>95%) active site homology between PDE3A and B represents a massive obstacle for obtaining selectivity at the active site; however, utilization of libraries with high molecular diversity in high throughput screens may uncover selective chemical matter. Herein, we employed a DNA-encoded library screen to identify PDE3B-selective inhibitors and identified potent and selective boronic acid compounds bound at the active site.

The high molecular diversity in Noctiluca scintillans is dominated by intra-genomic variations revealed by single cell high-throughput sequencing of 18S rDNA V4

The application of high-throughput sequencing (HTS) technologies has revolutionized research on phytoplankton biodiversity by generating an unprecedented amount of molecular data in marine ecosystem surveys. However, high-level of molecular diversity uncovered in HTS-based metabarcoding analyses may lead to overinterpretation of phytoplankton diversity due to excessive intra-genomic variations (IGVs). The aims in this study are to explore the nature of phytoplankton molecular diversity and to test the hypothesis. We carried out single-cell metabarcoding analysis of 18S rDNA V4 sequences obtained in single Noctiluca scintillans cells isolated from various sites in coastal waters of China. Results showed that each single N. scintillans cell harbored a high level of IGVs with about 100 amplicon sequence variants (ASVs). The large numbers of non-dominant ASVs identified in N. scintillans cells, which might correspond to the larger numbers of ASVs annotated as N. scintillans and showed similar temporal dynamics in metabarcoding analyses, could inflate the inter-species diversity or intra-species genetic diversity. In addition, there were large numbers of additional ASVs that were not annotated as N. scintillans. These non-N. scintillans ASVs might represent diverse preys for N. scintillans, consistent with previous reports that N. scintillans may act as chance predator of a broad-spectrum preys. This single-cell study has unambiguously demonstrated that the existence of high levels of IGVs in N. scintillans and most likely many other phytoplankton species, demonstrating that the majority of the molecular diversity revealed in metabarcoding analysis, which were generally interpreted as the sum of inter-species diversity and intra-species diversity, actually included high levels of IGVs and should be interpreted with caution.

Prevalence and molecular characterization of grapevine virus E, F and I populations in Greek vineyards

In this study, RT-PCR assays were developed and applied to investigate the prevalence of grapevine virus E (GVE), grapevine virus F (GVF) and grapevine virus I (GVI) in Greek vineyards. Grapevine samples from different viticultural areas of Greece were tested and the presence of all three vitiviruses was revealed. These viruses were mainly detected in grafted indigenous grapevine cultivars, with GVF being the most prevalent (24.7%, 200/809) in contrast to GVI (2.2%, 12/554) and GVE (1.6%, 12/752). To further study their intraspecies genetic variability and the phylogenetic relationships of their populations, sequence similarity analyses of the replicase and the coat protein gene segments of each virus, as well as from a fragment of the movement protein gene of GVI, were performed. Results revealed genetic variability in all three virus populations and high molecular diversity between Greek isolates of GVE and GVF, in contrast to Greek GVI isolates, which showed high homogeneity. Overall, our study advanced the current knowledge on grapevine-infecting vitiviruses and highlighted that special attention should be given to the widely spread GVF and its impact on grapevine should be further investigated.

Soluble organic matter Molecular atlas of Ryugu reveals cold hydrothermalism on C-type asteroid parent body

The sample from the near-Earth carbonaceous asteroid (162173) Ryugu is analyzed in the context of carbonaceous meteorites soluble organic matter. The analysis of soluble molecules of samples collected by the Hayabusa2 spacecraft shines light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity of Ryugu samples are analyzed using mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy. Here we show a continuum in the molecular size and polarity, and no organomagnesium molecules are detected, reflecting a low temperature and water-rich environment on the parent body approving earlier mineralogical and chemical data. High abundance of sulfidic and nitrogen rich compounds as well as high abundance of ammonium ions confirm the water processing. Polycyclic aromatic hydrocarbons are also detected in a structural continuum of carbon saturations and oxidations, implying multiple origins of the observed organic complexity, thus involving generic processes such as earlier carbonization and serpentinization with successive low temperature aqueous alteration.

Analysis of some flavonoids for inhibitory mechanism against cancer target phosphatidylinositol 3-kinase (PI3K) using computational tool.

Cancer has been one of the leading causes of mortality worldwide over the past few years. Some progress has been made in the development of more effective cancer therapeutics, resulting in improved survival rates. However, the desired outcome in the form of successful treatment is yet to be achieved. There is high demand for the development of innovative, inexpensive, and effective anticancer treatments using natural resources. Natural compounds have been increasingly discovered and used for cancer therapy owing to their high molecular diversity, novel biofunctionality, and minimal side effects. These compounds can be utilized as chemopreventive agents because they can efficiently inhibit cell growth, control cell cycle progression, and block several tumor-promoting signaling pathways. PI3K is an important upstream protein of the PI3K-Akt-mTOR pathway and a well-established cancer therapeutic target. This study aimed to explore the small molecules, natural flavonoids, viz. quercetin, luteolin, kaempferol, genistein, wogonin, daidzein, and flavopiridol for PI3Kγ kinase activity inhibition. In this study, the binding pose, interacting residues, molecular interactions, binding energies, and dissociation constants were investigated. Our results showed that these flavonoids bound well with PI3Kγ with adequate binding strength scores and binding energy ranging from (-8.19 to -8.97Kcal/mol). Among the explored ligands, flavopiridol showed the highest binding energy of -8.97Kcal/mol, dock score (-44.40), and dissociation constant term, of 6.58 against PI3Kγ. Based on the above results, the stability of the most promising ligand, flavopiridol, against PI3Kγ was evaluated by molecular dynamics simulations for 200ns, confirming the stable flavopiridol and PI3Kγ complex. Our study suggests that among the selected flavonoids specifically flavopiridol may act as potential inhibitors of PI3Kγ and could be a therapeutic alternative to inhibit the PI3Kγ pathway, providing new insights into rational drug discovery research for cancer therapy.

Characterization of Alternaria alternata isolates from different citrus species grown in Tunisian Cap Bon peninsula

AbstractThe prospection of citrus trees affected by Alternaria alternata in Tunisian Cap Bon peninsula for 2 years, 2018 and 2019, showed a variation in the percentage of isolation frequency depending on the region, age of citrus trees and citrus species and varieties. Thirty isolates of A. alternata from citrus species were characterized and studied for their variability. The isolates were subjected to morphological identification using macroscopic and microscopic features and molecular characterization through PCR amplification of their internal transcribed spacer regions. A high morphological and molecular diversity within A. alternata isolates was detected. The molecular sequencing results precisely confirmed that these fungal isolates belong to A. alternata strains. Pathogenicity test showed that A. alternata T1 and T9 isolates were capable of causing disease symptoms only on young leaves of clementine plant (MA3 variety). These findings are useful in the development of sustainable strategies to manage Alternaria in citrus‐growing areas in Tunisia.

Drought stress memory in orchard grass and the role of marker-based parental selection for physiological and antioxidant responses

Drought stress memory occurring in some plants plays a crucial role in their adaptation to unfavorable conditions. However, in open-pollinated plants, this phenomenon is assumed to be affected by population plasticity resulting from kind and level of diversity and inbreeding depression. Physiological perspectives of drought stress memory in four synthetic poly-crossed populations (groups) of orchard grass (Dactylis glomerata) constructed from parental genotypes with contrasting levels (narrow and wide) of molecular and morphological genetic variation were assessed. Populations of two generations (Syn1 and Syn2) were developed and were subjected to three moisture treatments, including normal irrigation (C), primary mild stress-secondary intense stress (D1D2), and secondary intense stress (D2). Pre-exposure to drought significantly improved the mean values of leaf water, chlorophyll, proline, and ascorbate peroxidase compared to intense stress, leading to more effective memory responses. Superiority of groups with high levels of molecular diversity for most traits, suggesting that the molecular genetic distance among parents is an effective predictor of progeny performance. The results indicated that the fitness of progenies of the four polycross groups declines significantly from Syn1 to Syn2, however the magnitude of observed inbreeding depends on the level of diversity and moisture conditions. We propose a hypothesis that underscores the interplay between genetic diversity among parents and drought stress memory providing valuable insights for developing new synthetic varieties in open-pollinated grasses. Specifically, we posit that higher molecular diversity among parental genotypes enhances the potential for robust drought stress memory, thereby contributing to improved progeny fitness under unfavorable conditions.

Photoredox‐Catalyzed Trifunctionalization of 5‐Heteroaryl‐Substituted 1‐Hexenes or 5‐hexenenitriles via Remote Heteroaryl or Cyano Group Migration

AbstractA photoredox‐catalyzed trifunctionalization of 5‐heteroaryl‐substituted 1‐hexenes via remote heteroaryl migration and a photoredox‐catalyzed trifunctionalization of 5‐hexenenitriles via cyano migration are reported. This protocol provides access to a broad scope of CFnR‐containing ketones with high molecular complexity and functional group diversity. The reaction features mild conditions and high chemo‐ and regioselectivities. The success of gram‐scale reactions and the versatility of products in derivative synthesis illustrated the potential value of this transformation in synthetic chemistry.

Acinetobacter baumannii Carbapenemase Producers in Morocco: Genetic Diversity.

Carbapenem resistance in Acinetobacter baumannii(A. baumannii) is a public health problem worldwide. Although carbapenem resistance is emerging in Morocco, few studies have shown the epidemiological profile of carbapenemase genes in Moroccan healthcare facilities. The aim of this study was to characterize the molecular profile of the carbapenemase enzyme in Acinetobacter baumannii from clinical isolates. Clinical strains isolated in the laboratory from various samples were subjected to several phenotypic tests. Antibiotic susceptibility and identification were tested using Phoenix 100 (Becton Dickinson Co., Sparks, MD, USA) and Api 20 (bioMérieux,Marcy-l'Etoile,France). Simple phenotypic assays were used to detect carbapenemase oxacillinase (OXA) and metallo-β-lactamase (MBL) production, including the modified Hodge test (MHT) and ethylenediaminetetraacetic acid (EDTA) test. The detection of carbapenemase genes was performed by multiplex and simple polymerase chain reaction (PCR). A total of 140 strainsor 100% of isolatescontained OXA-51 and ISbA1 sequences, 89% contained OXA-23 and OXA-58 sequences, and 1% contained OXA-24 sequence. The MBL genes were predominated by Verona integron-encodedmetallo-β-lactamase (VIM) (56%), followed by Seoul imipenemase (SIM) (39%), German imipenemase (GIM) (37%), São Paulo metallo-β-lactamase (SPM) (13%), imipenemase (IMP) (11%), and New Delhi metallo-β-lactamase (NDM) (4%). Guyana extended-spectrum β-lactamase (GES) was not found in any isolation. Our study shows a high frequency of carbapenem resistance in Acinetobacter baumannii, as it reports a high molecular diversity of carbapenemase-encoding genes, mainly dominated by the carbapenemase ISaba1/OXA-23, which represents an emerging threat in our hospital.

Characterization of copper-containing porphyrins in an insoluble fraction of a bio-crude obtained from hydrothermal liquefaction of wild microalgae

Among the various alternatives to fossil energies, microalga-based fuels are promising solutions. Thanks to their ability to grow under harsh conditions and trap industrial exhaust gases, these microalgae can help reduce global warming effects. One efficient way to process this feedstock is to use hydrothermal liquefaction (HTL) which leads to an intermediate bio-crude and a residual solid. This bio-crude can be further refined to produce usable biofuel by eliminating problematic heteroatoms such as nitrogen, oxygen, and metals. The residual solid, which can represent 50 % in mass is, however not useable nowadays. To valorize this insoluble fraction, the present work is focused on its molecular characterization and, in particular, on its metal content. Metals are particularly problematic for downstream processes when they are in an organic form such as porphyrins as they destroy catalysts. Identification and speciation of these metal organic species is thus needed. However, these analyses are challenging because of the high molecular diversity of these samples. Here, complementarity between electron paramagnetic resonance spectroscopy (EPR) and FTICR-MS, which is a state-of-the-art mass spectrometer, was used for the speciation of copper elements in the residual solid. A signal characteristic of a copper surrounded by four symmetric nitrogen atoms was observed in EPR, suggesting porphyrinic structures. The dynamic range of FTICR-MS broadband analyses was not sufficient to access the isotopic fine structure of the copper porphyrins. Continuous accumulation of selected ions analyses (CASI) was thus, performed to boost the dynamic range of the mass spectrometer in a narrower mass range allowed to confirm for the first time the presence of copper porphyrins in a residual solid of bio-crude. Different families of copper porphyrins were observed, and putative structures were proposed.

Molecular size-dependent compositions and lead (II) binding behaviors of two origins of organic fertilizers-derived dissolved organic matter

The application of organic fertilizers caused large amounts of dissolved organic matter (DOM) entering the soil environment and influencing the behaviors and fates of heavy metals. Here, we investigated the molecular weight-dependent (high molecular weight [HMW], 1 kDa-0.7 µm; low molecular weight [LMW], <1 kDa) compositions and lead (Pb) binding behaviors of DOM derived from sheep manure-based (SMOF) and shrimp peptide-based organic fertilizers (SPOF) using chromophoric and fluorescent spectroscopy, Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and two-dimensional correlation spectroscopy (2D-COS). Results showed that SMOF released more DOM with higher aromaticity and hydrophobicity, containing more fluvic-like components, carboxylic-rich alicyclic molecules (CRAMs) and lignin phenolic compounds compared to SPOF-DOM with more microbially-transformed heteroatom-containing compounds (CHON, CHONS and CHOS). Furthermore, there was more aromatic compounds with ample carboxyl and hydroxyl groups in HMW-DOM but abundant protein-like components and heteroatom-containing compounds (CHONS and CHOS) in LMW-DOM. SMOF-DOM exhibited more obvious MW-dependent heterogeneity in molecular components compared to SPOF-DOM with higher molecular diversity. Moreover, 2D-COS indicated phenol and carboxyl groups in SMOF-DOM and polysaccharides in SPOF-DOM exhibited superior binding affinities for Pb. Pb binding to HMW-DOM derived from SMOF first occurred in the phenolic groups in fulvic-like substances, while polysaccharides in LMW-DOM first participated in the binding of Pb. In contrast, irrespective of MWs, polysaccharides and humic-like substances with aromatic (CC) groups in SPOF-DOM displayed a faster response to Pb. Furthermore, the polysaccharides which preferentially participated in the binding of Pb to SPOF-DOM and SMOF-derived LMW-DOM may pose a higher risk of Pb in the environment. These results were helpful to understand the effects of sources and size-dependent compositions of DOM on the associated risks of heavy metals in the environments.