Search

The molecular mechanisms of exon definition and back-splicing are fundamental unanswered questions in pre-mRNA splicing. Here we report cryo-electron microscopy structures of the yeast spliceosomal E complex assembled on introns, providing a view of the earliest event in the splicing cycle that commits pre-mRNAs to splicing. The E complex architecture suggests that the same spliceosome can assemble across an exon, and that it either remodels to span an intron for canonical linear splicing (typically on short exons) or catalyses back-splicing to generate circular RNA (on long exons). The model is supported by our experiments, which show that an E complex assembled on the middle exon of yeast EFM5 or HMRA1 can be chased into circular RNA when the exon is sufficiently long. This simple model unifies intron definition, exon definition, and back-splicing through the same spliceosome in all eukaryotes and should inspire experiments in many other systems to understand the mechanism and regulation of these processes.

Objective To compare the disinfection effects of 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant applied to the threaded plastic hose at the fixed end of the saliva suction pipe of the oral comprehensive treatment table after diagnosis and treatment of patients in stomatology to provide a basis for clinical cleaning and disinfection. Methods The fixed ends of saliva suction pipes of 12 comprehensive treatment tables in the dental pulp department and maxillofacial surgery were selected as the research objects. The absorption was randomly divided into two groups and a control group: experimental group 1 with 500 mg/L chlorine disinfectants and experiment 2 group with 3% hydrogen peroxide disinfectant rinse disinfection and the control group with 0.9% sterile saline flushing pipe once a week for four weeks. Before and after washing and disinfection, samples from the inner wall of the threaded plastic hose interface were collected for bacterial culture and colony count, and colony counts within and between groups were compared before and after disinfection. Statistical analysis was conducted using SPSS 24.0 software. Results The baseline number of bacterial colonies in the first three groups was balanced, with no statistically significant difference (χ2 = 0.538, P = 0.764). The number of bacterial colonies after washing and disinfection was lower than that before washing and disinfection. The difference between 500 mg/L chlorine-containing disinfectant and 3% hydrogen peroxide disinfectant before and after disinfection was highly significant (Z = -4.801, P

Congo red (CR), a stable benzidine diazo dye due to its azo bonds, resists natural photodegradation and poses a significant ecological threat. Herein, organic photocatalyst material PM7:ITC-2Cl@C was integrated with natural biochar to establish a high-performance photocatalyst coupling with adsorption. PM7:ITC-2Cl@C demonstrated complete degradation of 100 mg L−1 CR in 10 min under indoor weak light, sustaining a degradation efficiency above 99% within 20 cycles. The removal efficiency of TOC content in a simulated aquatic environment containing 100 mg L−1 of CR was over 81%. PM7:ITC-2Cl@C possesses broad photon utilization (450–760 nm) and sequential measurements confirm its remarkable electron–hole separation, and the catalyst surface with functional groups containing oxygen and hydrogen also aids radical generation. Additionally, the strong adsorption of biochar fosters an environment for effective interaction with active oxygen species, ensuring constant pollutant contacting. Moreover, radical quench measurements indicated h+, ˙OH, and ˙O2− as key reactive oxygen species. The potential degradation pathways of CR were explored via LC-MS and DFT analysis, while toxicity analysis revealed low toxicity in the intermediates, suggesting the promising prospects of this system. This approach demonstrates high-performance PM7:ITC-2Cl@C to significantly enhance the catalytic oxidative degradation process of dying wastewater. [ABSTRACT FROM AUTHOR]

With the advancement of radar technology toward multifunctionality and cognitive capabilities, traditional radar countermeasures are no longer sufficient to meet the demands of countering the advanced multifunctional radar (MFR) systems. Rapid and accurate generation of the optimal jamming strategy is one of the key technologies for efficiently completing radar countermeasures. To enhance the efficiency and accuracy of jamming policy generation, an efficient jamming policy generation method based on multi-timescale ensemble Q-learning (MTEQL) is proposed in this paper. First, the task of generating jamming strategies is framed as a Markov decision process (MDP) by constructing a countermeasure scenario between the jammer and radar, while analyzing the principle radar operation mode transitions. Then, multiple structure-dependent Markov environments are created based on the real-world adversarial interactions between jammers and radars. Q-learning algorithms are executed concurrently in these environments, and their results are merged through an adaptive weighting mechanism that utilizes the Jensen–Shannon divergence (JSD). Ultimately, a low-complexity and near-optimal jamming policy is derived. Simulation results indicate that the proposed method has superior jamming policy generation performance compared with the Q-learning algorithm, in terms of the short jamming decision-making time and low average strategy error rate. [ABSTRACT FROM AUTHOR]

Simple Summary: Transposable elements (TEs) are mobile genetic elements that play vital role in defining and contributing to the size, shape and structure of both prokaryotic and eukaryotic genomes in nature. The piggyBac (PB), a superfamily of DNA transposons, has been isolated over the years from various organisms including insects, fungi and plants. These piggyBac transposon systems have high efficiency with a wide usage in the study of gene therapies, mutagenesis and transgenesis. Currently, there is limited information available on DNA transposons in small (compact) genomes of animals. Therefore, this study aims to annotate the PB transposons in small genomes of animals, revealing their evolution profiles in both vertebrate and invertebrate genomes. TEs, including DNA transposons, are major contributors of genome expansions, and have played a very significant role in shaping the evolution of animal genomes, due to their capacity to jump from one genomic position to the other. In this study, we investigated the evolution landscapes of PB transposons, including their distribution, diversity, activity and structure organization in 79 species of small (compact) genomes of animals comprising both vertebrate and invertebrates. Overall, 212 PB transposon types were detected from almost half (37) of the total number of the small genome species (79) investigated. The detected PB transposon types, which were unevenly distributed in various genera and phyla, have been classified into seven distinct clades or families with good bootstrap support (>80%). The PB transposon types that were identified have a length ranging from 1.23 kb to 9.51 kb. They encode transposases of approximately ≥500 amino acids in length, and possess terminal inverted repeats (TIRs) ranging from 4 bp to 24 bp. Though some of the transposon types have long TIRs (528 bp), they still maintain the consistent and reliable 4 bp target site duplication (TSD) of TTAA. However, PiggyBac-2_Cvir transposon originating from the Crassostrea virginica species exhibits a unique TSD of TATG. The TIRs of the transposons in all the seven families display high divergence, with a highly conserved 5′ end motif. The core transposase domains (DDD) were better conserved among the seven different families compared to the other protein domains, which were less prevalent in the vertebrate genome. The divergent evolution dynamics analysis also indicated that the majority of the PB transposon types identified in this study are either relatively young or old, with some being active. Additionally, numerous invasions of PB transposons were found in the genomes of both vertebrate and invertebrate animals. The data reveals that the PB superfamily is widely distributed in these species. PB transposons exhibit high diversity and activity in the small genomes of animals, and might play a crucial role in shaping the evolution of these small genomes of animals. [ABSTRACT FROM AUTHOR]