Synthesis of 4-thio-5-(2′′-thienyl)uridine and cytotoxicity activity against colon cancer cells <i>in vitro</i>

A novel anti-tumor agent 4-thio-5-(2′′-thienyl)uridine (6) was synthesized and the in vitro cytotoxicity activity against mice colon cancer cells (MC-38) and human colon cancer cells (HT-29) was evaluated by MTT assay. The results showed that the novel compound had antiproliferative activity toward MC-38 and HT-29 cells in a dose-dependent manner. The cell cycle analysis by flow cytometry indicated that compound 6 exerted in tumor cell proliferation inhibition by arresting HT-29 cells in the G2/M phase. In addition, cell death detected by propidium iodide staining showed that compound 6 efficiently induced cell apoptosis in a concentration-dependent manner. Moreover, the sensitivity of human fibroblast cells to compound 6 was far lower than that of tumor cells, suggesting the specific anti-tumor effect of 4-thio-5-(2′′-thienyl)uridine. Taken together, novel compound 6 effectively inhibits colon cancer cell proliferation, and hence would have potential value in clinical application as an antitumor agent

Flocculation phenomenon of a mutant flocculent Saccharomyces cerevisiae strain: Effects of metal ions, sugars, temperature, pH, protein-denaturants and enzyme treatments

The flocculation mechanism of a stable mutant flocculent yeast strainSaccharomyces cerevisiae KRM-1 was quantitatively investigated for potential industrial interest. It was found that the mutant flocculent strain was NewFlo phenotype by means of sugar inhibition test. The flocculation was completely inhibited by treatment with proteinase K, protein-denaturants and carbohydrate modifier. The absence of calcium ions significantly inhibited the flocculation, indicating that Ca2+ was specifically required for flocculation. The flocculation was stable when temperature below 70°C and pH was in the range of 3.0 - 6.0. The flocculation onset of the mutant flocculent strain was in the early stationary growth phase, which coincided with glucose depletion in the batch fermentation for the production of ethanol from kitchen refuse medium. The results are expected to help develop better strategies for the control of mutant flocculent yeast for future large-scale industrial ethanol fermentation

Enhanced fuel ethanol production from rice straw hydrolysate by an inhibitor-tolerant mutant strain of Scheffersomyces stipitis

The aim of the present study was to develop an inhibitor-tolerant strain of Scheffersomyces stipitis and establish an efficient ethanol fermentation process for cost-effective ethanol production from lignocellulosic biomass. By a strategy of three successive rounds of UV mutagenesis following adaptation, we isolated a S. stipitis mutant with improved tolerance against ethanol and inhibitors in the form of acetic acid, furfural and vanillin. The mutant strain exhibited excellent ethanol fermentation performance; both the xylose and glucose consumption rate and ethanol productivity were almost two times higher than the parental strain in batch fermentation. To overcome the issue of product inhibition and carbon catabolite repression (CCR) effect, the membrane integrated continuous fermentation system was employed. The maximum ethanol titer of 43.2 g l−1 and productivity of 2.16 g l−1 h−1 was achieved at a dilution rate of 0.05 h−1, higher than the relevant studies ever reported. These results suggested the novel process of cell recycling continuous fermentation using S. stipitis mutant has great potential for commercial ethanol production from lignocelluloses-based biomass

The Synthesis of (E)-4-Thio-5-(2-Bromovinyl)Uridine/Deoxyuridine and Its Characterization and Cytotoxicity

(E)-4-Thio-5-(2-brominevinyl)uridine/2'-deoxyuridine(8a/8b) were efficiently and in an environmental friendly way synthesized from uridine/2'-deoxyuridine (1a/1b) that were first transformed to (E)-(2-brominevinyl) uridine / 2'-deoxyuridine(5a/5b) via iodination, selective oxidation, Heck reaction steps. The resulting products (5a/5b) were then converted to the targets (8a/8b) through esterification, thio-reaction of carbonyl, hydrolysis steps. Two new compounds (8a/8b) and three new intermediates (7a 7b 10) were obtained, and their structures have been fully characterized by 1H NMR, 13C NMR, IR, UV, HR-MS, X-Ray. The study of 8a and their derivatives regarding cytotoxicity was carried out by using MTT experiment method, and the initial findings suggest (E)-4-Thio-5-(2-brominevinyl) uridine/ 2'-deoxyuridine (8a / 8b) would be potential antitumor drugs

Regulatory network of ammonium and nitrate uptake and utilization in rice

Nitrogen (N) plays a crucial role in various aspects of crop growth, development, yield, and quality. It is essential for processes ranging from protein synthesis and photosynthesis to crop adaptation and stress tolerance, thereby having a profound impact on crop production. Crops primarily absorb N in the forms of ammonium (NH4+) and nitrate (NO3-), with NH4+ being the predominant form absorbed by flooded crops such as rice. This review focuses on rice and highlights recent significant advances in the mechanisms of N uptake and utilization, including the roles of NO3- and NH4+ transporters. Key transporters such as OsAMT1.1 and OsNRT1.1B play central roles in enhancing N uptake and improving N use efficiency (NUE). Furthermore, natural allelic variations in genes such as DNR1 and OsWRKY23 underlie the differences in NUE between indica and japonica subspecies. We also discuss the potential of multi-gene pyramiding strategies, such as OsAMT1.2×OsGS1.2×OsAS1, to synergistically improve NUE through coordinated regulation of N uptake, assimilation, and remobilization. Collectively, this review systematically summarizes the functions and regulatory mechanisms of key NUE-related genes in rice, providing valuable gene resources and a theoretical foundation for the molecular breeding of N-efficient rice varieties

3D bioactive composite scaffolds for bone tissue engineering

Bone is the second most commonly transplanted tissue worldwide, with over four million operations using bone grafts or bone substitute materials annually to treat bone defects. However, significant limitations affect current treatment options and clinical demand for bone grafts continues to rise due to conditions such as trauma, cancer, infection and arthritis. Developing bioactive three-dimensional (3D) scaffolds to support bone regeneration has therefore become a key area of focus within bone tissue engineering (BTE). A variety of materials and manufacturing methods including 3D printing have been used to create novel alternatives to traditional bone grafts. However, individual groups of materials including polymers, ceramics and hydrogels have been unable to fully replicate the properties of bone when used alone. Favourable material properties can be combined and bioactivity improved when groups of materials are used together in composite 3D scaffolds. This review will therefore consider the ideal properties of bioactive composite 3D scaffolds and examine recent use of polymers, hydrogels, metals, ceramics and bio-glasses in BTE. Scaffold fabrication methodology, mechanical performance, biocompatibility, bioactivity, and potential clinical translations will be discussed

Two-Dimensional Platinum Telluride with Ordered Te Vacancy Superlattice for Efficient and Robust Hydrogen Evolution

Defect engineering to activate the basal planes of transition metal dichalcogenides (TMDs) is critical for the development of TMD-based electrocatalysts as the chemical inertness of basal planes restrict their potential applications in hydrogen evolution reaction (HER). Here, we report the synthesis and evaluation of few-layer (7x7)-PtTe2-x with an ordered, well-defined and high-density Te vacancy superlattice. Compared with pristine PtTe2, (2x2)-PtTe2-x and Pt(111), (7x7)-PtTe2-x exhibits superior HER activities in both acidic and alkaline electrolytes due to its rich structures of undercoordinated Pt sites. Furthermore, the (7x7)-PtTe2-x sample features outstanding catalytic stability even compared to the state-of-the-art Pt/C catalyst. Theoretical calculations reveal that the interactions between various undercoordinated Pt sites due to proximity effect can provide superior undercoordinated Pt sites for hydrogen adsorption and water dissociation. This work will enrich the understanding of the relationship between defect structures and electrocatalytic activities and provide a promising route to develop efficient Pt-based TMD electrocatalysts

Evolution of HD-ZIP transcription factors and their function in cabbage leafy head formation

IntroductionThe HD-ZIP protein, a unique class of transcription factors in plants, plays a crucial role in plant growth and development. Although some HD-ZIP transcription factors have been associated with leafy head formation in Chinese cabbage, their regulatory mechanisms remain poorly understood.MethodsThis study identified the HD-ZIP family using HMM and TBtools, constructed a phylogenetic tree with OrthoFinder, and analyzed gene family expansion and contraction using CAFE. Conserved features were analyzed with MAFFT, MEME, and TBtools; regulatory networks were predicted using ATRM and PlantTFDB; and gene expression was validated by qRT-PCR.Results and discussionIn this study, HD-ZIP gene sequences from 87 species were analyzed to explore the evolutionary history of this gene family. Despite significant variation in gene family expansion and contraction across species, our findings indicated that HD-ZIP family proteins were conserved in both lower (Charophyta) and higher plants, where they were potentially involved in root, stem, and leaf differentiation. In our analysis of 22 Brassica species, HD-ZIP III protein sequences and domains were conserved. However, within the pan-genome A of 18 Brassica rapa species, differences were observed in auxin-related cis-elements within the HD-ZIP III promoter regions between heading and non-heading cabbage varieties. RNA-seq analysis of wild-type A03 (heading) and mutant fg-1 (non-heading) revealed that 131 genes formed a protein interaction network or clustered in the same branch as HD-ZIP family genes. Through GO enrichment and qRT-PCR, several key candidate genes of Brassica rapa ssp. pekinensis A03 associated with leafy head formation in cabbage were identified. These findings established a foundation for understanding the molecular mechanisms by which the HD-ZIP gene family regulated head growth in Chinese cabbage

Distinct Topological Surface States on the Two Terminations of MnBi4_4Te7_7

The recent discovered intrinsic magnetic topological insulator MnBi2Te4 have been met with unusual success in hosting emergent phenomena such as the quantum anomalous Hall effect and the axion insulator states. However, the surface-bulk correspondence of the Mn-Bi-Te family, composed by the superlattice-like MnBi2Te4/(Bi2Te3)n (n = 0, 1, 2, 3 ...) layered structure, remains intriguing but elusive. Here, by using scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) techniques, we unambiguously assign the two distinct surface states of MnBi4Te7 (n = 1) to the quintuple-layer (QL) Bi2Te3 termination and the septuple-layer (SL) MnBi2Te4 termination, respectively. A comparison of the experimental observations with theoretical calculations reveals the diverging topological behaviors, especially the hybridization effect between magnetic and nonmagnetic layers, on the two terminations: a gap on the QL termination originating from the topological surface states of the QL hybridizing with the bands of the beneath SL, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry. The quasi-particle interference patterns further confirm the topological nature of the surface states for both terminations, continuing far above the Fermi energy. The QL termination carries a spin-helical Dirac state with hexagonal warping, while at the SL termination, a strongly canted helical state from the surface lies between a pair of Rashba-split states from its neighboring layer. Our work elucidates an unprecedented hybridization effect between the building blocks of the topological surface states, and also reveals the termination-dependent time-reversal symmetry breaking in a magnetic topological insulator, rendering an ideal platform to realize the half-integer quantum Hall effect and relevant quantum phenomena.Comment: 22 Pages, 4 Figure