Loss of an ABC transporter in Arabidopsis thaliana confers hypersensitivity to the anti-cancer drug bleomycin

The SMC5/6 complex recruits the PAF1 complex to facilitate DNA double-strand break repair in Arabidopsis

DNA double-strand breaks (DSBs) are one of the most toxic forms of DNA damage, which threatens genome stability. Homologous recombination is an error-free DSB repair pathway, in which the evolutionarily conserved SMC5/6 complex (SMC5/6) plays essential roles. The PAF1 complex (PAF1C) is well known to regulate transcription. Here we show that SMC5/6 recruits PAF1C to facilitate DSB repair in plants. In a genetic screen for DNA damage response mutants (DDRMs), we found that the Arabidopsis ddrm4 mutant is hypersensitive to DSB-inducing agents and is defective in homologous recombination. DDRM4 encodes PAF1, a core subunit of PAF1C. Further biochemical and genetic studies reveal that SMC5/6 recruits PAF1C to DSB sites, where PAF1C further recruits the E2 ubiquitin-conjugating enzymes UBC1/2, which interact with the E3 ubiquitin ligases HUB1/2 to mediate the monoubiquitination of histone H2B at DSBs. These results implicate SMC5/6-PAF1C-UBC1/2-HUB1/2 as a new axis for DSB repair through homologous recombination, revealing a new mechanism of SMC5/6 and uncovering a novel function of PAF1C.

Study on the Metabonomics Mechanism of Mongolian Medical Andai Therapy on Healthy People

Andai therapy is a traditional therapy combining body, mind, and language with Mongolian characteristics. In the form of singing and dancing, it is widely popular among people of all ages in Mongolian areas of Inner Mongolia. According to Mongolian medicine, Heyi is one of the three elements of human body, and it can maintain life activities, promote blood circulation, and improve the functions of the sensory and mental consciousness. Andai therapy stimulates the whole body nerves and Heyi through music and dance, improves Heyi and blood operation, strengthens physique, improves immunity, effectively promotes physical and mental health, and plays a role in preventing and treating diseases. Objective. In this study, gas chromatography-mass spectrometry (GC-MS) was used to explore the mechanism of Andai therapy, so as to provide a new research direction for taking targeted prevention and treatment measures for diseases. Methods. Using gas chromatography-mass spectrometry (GC-MS) on all its cases baseline plasma to the targeted metabonomics testing, the differential metabolites of the experimental group (receiving Andai therapy) and control group (without receiving Andai therapy), analysis-related metabolite function, and screening of metabolites and related pathways through adjusting mechanism to explore the related factors are compared, to study the mechanism of the influence of Mongolian medical Andai therapy on the metabolism of different healthy people. Results. The differences in metabolic numbers between the experimental group and the control group are 114, such as cyclohexylamine chlorinated acid, 2,4-2 aminobutyric acid bitter almond alcohol, l-methyl inosine, 2-picolinate, and 2-hydroxy-2-glutaric acid metabolite content of the control group that are significantly higher than the experimental group, experimental group’s other substance content is significantly higher than that of the control group, and two groups’ metabolite content was obviously different. The number of differential metabolites between the female experimental group and the female control group was 119, and the number of differential metabolites between the male experimental group and the male control group was 48.

Comparative Transcriptome Analysis Reveals New Insight of Alfalfa (Medicago sativa L.) Cultivars in Response to Abrupt Freezing Stress

Freezing stress is a major limiting environmental factor that affects the productivity and distribution of alfalfa (Medicago sativa L.). There is growing evidence that enhancing freezing tolerance through resistance-related genes is one of the most efficient methods for solving this problem, whereas little is known about the complex regulatory mechanism of freezing stress. Herein, we performed transcriptome profiling of the leaves from two genotypes of alfalfa, freezing tolerance "Gannong NO.3" and freezing-sensitive "WL326GZ" exposure to -10°C to investigate which resistance-related genes could improve the freezing tolerance. Our results showed that a total of 121,366 genes were identified, and there were 7,245 differentially expressed genes (DEGs) between the control and treated leaves. In particular, the DEGs in "Gannong NO.3" were mainly enriched in the metabolic pathways and biosynthesis of secondary metabolites, and most of the DEGs in "WL326GZ" were enriched in the metabolic pathways, the biosynthesis of secondary metabolites, and plant-pathogen interactions. Moreover, the weighted gene co-expression network analysis (WGCNA) showed that ATP-binding cassette (ABC) C subfamily genes were strongly impacted by freezing stress, indicating that ABCC8 and ABCC3 are critical to develop the freezing tolerance. Moreover, our data revealed that numerous Ca2+ signal transduction and CBF/DREB1 pathway-related genes were severely impacted by the freezing resistance, which is believed to alleviate the damage caused by freezing stress. Altogether, these findings contribute the comprehensive information to understand the molecular mechanism of alfalfa adaptation to freezing stress and further provide functional candidate genes that can adapt to abiotic stress.