Diversity and Activity of Soil N2O-Reducing Bacteria Shaped by Urbanization.

Nitrous oxide (N2O) is a potent greenhouse gas with various production pathways. N2O reductase (N2OR) is the primary N2O sink, but the distribution of its gene clades, typically nosZI and atypically nosZII, along urbanization gradients remains poorly understood. Here we sampled soils from forests, parks, and farmland across eight provinces in eastern China, using high-throughput sequencing to distinguish between two N2O-reducing bacteria clades. A deterministic process mainly determined assemblies of the nosZI communities. Homogeneous selection drove nosZI deterministic processes, and both homogeneous and heterogeneous selection influenced nosZII. This suggests nosZII is more sensitive to environmental changes than nosZI, with significant changes in community structure over time or space. Ecosystems with stronger anthropogenic disturbance, such as urban areas, provide diverse ecological niches for N2O-reducing bacteria (especially nosZII) to adapt to environmental fluctuations. Structural equation modeling (SEM) and correlation analyses revealed that pH significantly influences the community composition of both N2O-reducing bacteria clades. This study underscores urbanization's impact on N2O-reducing bacteria in urban soils, highlighting the importance of nosZII and survival strategies. It offers novel insights into the role of atypical denitrifiers among N2O-reducing bacteria, underscoring their potential ecological importance in mitigating N2O emissions from urban soils.

Synthesis of α-Boryl Ketones via Hydration or Oxidation of B(MIDA)-Decorated Alkynes.

α-Boryl ketones are traditionally challenging targets in organic synthesis. Reported herein is a mild and metal-free synthesis of α-boryl ketones via the hydration or oxidation of N-methyliminodiacetyl boronate (B(MIDA))-decorated alkynes. A new hydration system comprised of AcCl and H2O in HFIP allows the hydration of arylethynyl B(MIDA)s at room temperature with decent functional group tolerance. An oxidative carbon deletion process of propargylic B(MIDA)s is also developed for the synthesis of aliphatic α-boryl ketones. An intriguing ß-boron effect was observed to account for the unique site- and chemoselectivities. The application of the products in the synthesis of borylated heterocycles was demonstrated.

Characterization of microbial community, ecological functions and antibiotic resistance in estuarine plastisphere.

The plastisphere is a new ecological niche. Compared to the surrounding water, microbial community composition associated with the plastisphere is known to differ with functional consequences. Here, this study characterized the bacterial and fungal communities associated with four types of plastisphere (polyethylene, polystyrene, polypropylene and polyvinyl chloride) in an estuarine habitat; assessed ecological functions including carbon, nitrogen, phosphorus and sulfur cycling, and determined the presence of antibiotic resistance genes (ARGs) and human pathogens. Stochastic processes dominated the community assembly of microorganisms on the plastisphere. Several functional genera related to nutrient cycling were enriched in the plastisphere. Compared to surrounding water and other plastisphere, the abundances of carbon, nitrogen and phosphorus cycling genes (cdaR, nosZ and chpy etc.) and ARGs (aadA2-1, cfa and catB8 etc.) were significantly increased in polyvinyl chloride plastisphere. In contrast, the polystyrene plastisphere was the preferred substrate for several pathogens being enriched with for example, Giardia lamblia 18S rRNA, Klebsiella pneumoniae phoE and Legionella spp. 23S rRNA. Overall, this study showed that different plastisphere had different effects on ecological functions and health risk in estuaries and emphasizes the importance of controlling plastic pollution in estuaries. Data from this study support global policy drivers that seek to reduce plastic pollution and offer insights into ecological functions in a new ecological niche of the Anthropocene.

Uncovering the diversity and contents of gene cassettes in class 1 integrons from the endophytes of raw vegetables.

Rapid spread of antibiotic resistance genes (ARGs) in pathogens is threatening human health. Integrons allow bacteria to integrate and express foreign genes, facilitating horizontal transfer of ARGs in environments. Consumption of raw vegetables represents a pathway for human exposure to environmental ARGs. However, few studies have focused on integron-associated ARGs in the endophytes of raw vegetables. Here, based on the approach of qPCR and clone library, we quantified the abundance of integrase genes and analyzed the diversity and contents of resistance gene cassettes in class 1 integrons from the endophytes of six common raw vegetables. The results revealed that integrase genes for class 1 integron were most prevalent compared with class 2 and class 3 integron integrase genes (1-2 order magnitude, P < 0.05). The cucumber endophytes harbored a higher absolute abundance of integrase genes than other vegetables, while the highest bacterial abundance was detected in cabbage and cucumber endophytes. Thirty-two unique resistance gene cassettes were detected, the majority of which were associated with the genes encoding resistance to beta-lactam and aminoglycoside. Antibiotic resistance gene cassettes accounted for 52.5 % of the functionally annotated gene cassettes, and blaTEM-157 and aadA2 were the most frequently detected resistance cassettes. Additionally, carrot endophytes harbored the highest proportion of antibiotic resistance gene cassettes in the class 1 integrons. Collectively, these results provide an in-depth view of acquired resistance genes by integrons in the raw vegetable endophytes and highlight the potential health risk of the transmission of ARGs via the food chain.

Design, synthesis, and evaluation of 9-(pyrimidin-2-yl)-9H-carbazole derivatives disrupting mitochondrial homeostasis in human lung adenocarcinoma.

Since more than 85% of lung cancer cases are non-small cell lung cancer (NSCLC), finding novel agents with anti-tumor activities is meaningful for NSCLC patients. Mitochondria is essential for cellular energy metabolism in cancer, and regulating mitochondrial bioenergetics is emerging as a practical approach for cancer treatment and prevention. The carbazole scaffold is an active structure showing anti-cancer biological activity, and the structural diversity has been expanded through the improvement and optimization of synthesizing methods. To find novel carbazole derivatives with great anti-tumor potential and explore structures variety, we designed and synthesized a series of 9-(pyrimidin-2-yl)-9H-carbazole derivatives based on the previously reported Cp∗Rh(III)/H+ tandem catalytic system. With thoroughly bioactivity exploration, we found benzo[d] [1,3]dioxol-5-yl(9-(pyrimidin-2-yl)-9H-carbazol-1-yl)methanone (compound 5n) showed notable activity in disrupting the mitochondrial homeostasis, induced cell cycle arrest and apoptosis in human adenocarcinoma cells, and finally showed anti-tumor activity in an NSCLC-xenograft mice model.

MYC modulators in cancer: a patent review.

INTRODUCTION: The important role of MYC in tumorigenesis makes it particularly important to design MYC modulators. Over the past decade, researchers have raised a number of strategies for designing MYC modulators, some of which are already in clinical trials. This paper aims to review the patents of MYC modulators. AREAS COVERED: The important biological relevance of c-MYC and the regulation pathways related to c-MYC are briefly introduced. Base on that, the MYC modulators reported in published patents and references primarily for cancer treatment are outlined, highlighting the structures and biological activities. EXPERT OPINION: There has been a growing awareness of finding and designing MYC modulators as novel anticancer drugs over recent years. Patents involving the discovery, synthesis, and application of MYC modulators are particularly important for further development in this field. Although finding direct MYC inhibitors or binders is challenging, MYC cannot be simply defined as an undruggable target. There is still substantial evidence proving the concept that MYC modulators can benefit to the treatment of both human hematological malignancies and solid tumors. More efforts should be taken to improve the activity and specificity of MYC modulators.

Developing Novel G-Quadruplex Ligands: from Interaction with Nucleic Acids to Interfering with Nucleic Acid⁻Protein Interaction.

G-quadruplex is a special secondary structure of nucleic acids in guanine-rich sequences of genome. G-quadruplexes have been proved to be involved in the regulation of replication, DNA damage repair, and transcription and translation of oncogenes or other cancer-related genes. Therefore, targeting G-quadruplexes has become a novel promising anti-tumor strategy. Different kinds of small molecules targeting the G-quadruplexes have been designed, synthesized, and identified as potential anti-tumor agents, including molecules directly bind to the G-quadruplex and molecules interfering with the binding between the G-quadruplex structures and related binding proteins. This review will explore the feasibility of G-quadruplex ligands acting as anti-tumor drugs, from basis to application. Meanwhile, since helicase is the most well-defined G-quadruplex-related protein, the most extensive research on the relationship between helicase and G-quadruplexes, and its meaning in drug design, is emphasized.

Design, Synthesis, and Evaluation of Novel p-(Methylthio)styryl Substituted Quindoline Derivatives as Neuroblastoma RAS (NRAS) Repressors via Specific Stabilizing the RNA G-Quadruplex.

The human proto-oncogene neuroblastoma RAS ( NRAS) contains a guanine-rich sequence in the 5'-untranslated regions (5'-UTR) of the mRNA that could form an RNA G-quadruplex structure. This structure acts as a repressor for NRAS translation and could be a potential target for anticancer drugs. Our previous studies found an effective scaffold, the quindoline scaffold, for binding and stabilizing the DNA G-quadruplex structures. Here, on the basis of the previous studies and reported RNA-specific probes, a series of novel p-(methylthio)styryl substituted quindoline (MSQ) derivatives were designed, synthesized, and evaluated as NRAS RNA G-quadruplex ligands. Panels of experiments turned out that the introduction of p-(methylthio)styryl side chain could enhance the specific binding to the NRAS RNA G-quadruplex. One of the hits, 4a-10, showed strong stabilizing activity on the G-quadruplex and subsequently repressed NRAS's translation and inhibited tumor cells proliferation. Our finding provided a novel strategy to discover novel NRAS repressors by specifically binding to the RNA G-quadruplex in the 5'-UTR of mRNA.

Discovery of Novel 11-Triazole Substituted Benzofuro[3,2-b]quinolone Derivatives as c-myc G-Quadruplex Specific Stabilizers via Click Chemistry.

The specificity of nucleic acids' binders is crucial for developing this kind of drug, especially for novel G-quadruplexes' binders. Quindoline derivatives have been developed as G-quadruplex stabilizers with good interactive activities. In order to improve the selectivity and binding affinity of quindoline derivatives as c-myc G-quadruplex binding ligands, novel triazole containing benzofuroquinoline derivatives (T-BFQs) were designed and synthesized by using the 1,3-dipolar cycloaddition of a series of alkyne and azide building blocks. The selectivity toward c-myc G-quadruplex DNA of these novel T-BFQs was significantly improved, together with an obvious increase on binding affinity. Further cellular and in vivo experiments indicated that the T-BFQs showed inhibitory activity on tumor cells' proliferation, presumably through the down-regulation of transcription of c-myc gene. Our findings broadened the modification strategies of specific G-quadruplex stabilizers.