Handbook of SAS® DATA Step Programming

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Mitochondrial signalling is critical for acclimation and adaptation to flooding in Arabidopsis thaliana

Mitochondria have critical functions in the acclimation to abiotic and biotic stresses. Adverse environmental conditions lead to increased demands in energy supply and metabolic intermediates, which are provided by mitochondrial ATP production and the tricarboxylic acid (TCA) cycle. Mitochondria also play a role as stress sensors to adjust nuclear gene expression via retrograde signalling with the transcription factor (TF) ANAC017 and the kinase CDKE1 key components to integrate various signals into this pathway. To determine the importance of mitochondria as sensors of stress and their contribution in the tolerance to adverse growth conditions, a comparative phenotypical, physiological and transcriptomic characterisation of Arabidopsis mitochondrial signalling mutants (cdke1/rao1andanac017/rao2) and a set of contrasting accessions was performed after applying the complex compound stress of submergence. Our results showed that impaired mitochondrial retrograde signalling leads to increased sensitivity to the stress treatments. The multi-factorial approach identified a network of 702 co-expressed genes, including several WRKY TFs, overlapping in the transcriptional responses in the mitochondrial signalling mutants and stress-sensitive accessions. Functional characterisation of two WRKY TFs (WRKY40andWRKY45), using both knockout and overexpressing lines, confirmed their role in conferring tolerance to submergence. Together, the results revealed that acclimation to submergence is dependent on mitochondrial retrograde signalling, and underlying transcriptional re-programming is used as an adaptation mechanism

Serum bilirubin is negatively associated with white blood cell count

OBJECTIVE: Bilirubin is considered an important antioxidant, anti-inflammatory factor and immunomodulator. The current investigation aimed to explore the association between bilirubin and white blood cell (WBC) count in a large Chinese cohort. METHODS: A total of 61091 participants (29259 males, 31832 females) were recruited from a Chinese tertiary hospital. Data were sorted by sex, and the association between bilirubin and WBC count was analyzed after dividing bilirubin levels into quartiles. RESULTS: Most parameters (including age, body mass index, systolic blood pressure, diastolic blood pressure, alanine aminotransferase, total bilirubin, blood urea nitrogen, creatinine, uric acid, triglycerides and WBC count) were significantly higher in men than in women. Bilirubin displayed significant negative relationships with most other measured variables. Linear logistic regression analysis further indicated their negative relationships. Females showed a significantly higher frequency of leucopenia than males. Significant associations of leucopenia with high bilirubin quartiles were shown in binary logistic regression models for both sexes, with a much closer association in men than in women. For instance, for men with bilirubin levels in quartile 4, the adjusted likelihood of leucopenia was 1.600-times higher than that of men with values in quartile 1. For women with bilirubin levels in quartile 4, the adjusted likelihood of leucopenia was 1.135-times higher than that of women with values in quartile 1. CONCLUSION: Bilirubin is negatively related to WBC count. Significant associations exist between leucopenia and high bilirubin quartiles, and these associations are more obvious in men than in women

ANAC017 coordinates organellar functions and stress responses by reprogramming retrograde signaling

Mitochondria adjust their activities in response to external and internal stimuli to optimize growth via the mitochondrial retrograde response (MRR) signaling pathway. The Arabidopsis (Arabidopsis thaliana) NAC domain transcription factor ANAC017 has previously been identified as a regulator of the MRR. We show here that overexpression of ANAC017 in Arabidopsis leads to growth retardation, altered leaf development with decreased cell size and viability, and early leaf senescence. RNA-seq analyses revealed increased ANAC017 expression leads to higher expression of genes related to mitochondrial stress, cell death/autophagy, and leaf senescence under non-limiting growth conditions, as well as extensive repression of chloroplast function. Gene regulatory network analysis indicated that a complex hierarchy of transcription factors exists downstream of ANAC017. These involve a set of up-regulated ANAC and WRKY transcription factors associated with organellar signaling and senescence. The network also includes a number of ethylene- and gibberellic acid-related transcription factors with established function in stress responses and growth regulation, which down-regulate their target genes. A number of BASIC LEUCINE-ZIPPER MOTIF transcription factors involved in the endoplasmic reticulum unfolded protein response or balancing of energy homeostasis via the SNF1-RELATED PROTEIN KINASE1 were also down-regulated by ANAC017 overexpression. Our results show that the endoplasmic reticulum membrane-tethering of the constitutively expressed ANAC017, and its controlled release, are crucial to fine-tune a fast reactive but potentially harmful signaling cascade. Thus, ANAC017 is a master regulator of cellular responses with mitochondria acting as central sensors

GWAS on multiple traits identifies mitochondrial ACONITASE3 as important for acclimation to submergence stress

Mitochondrial ACONITASE3 is important for the acclimation to submergence stress by integrating carbon and nitrogen metabolism and impacting stress signaling pathways. Flooding causes severe crop losses in many parts of the world. Genetic variation in flooding tolerance exists in many species; however, there are few examples for the identification of tolerance genes and their underlying function. We conducted a genome-wide association study (GWAS) in 387 Arabidopsis (Arabidopsis thaliana) accessions. Plants were subjected to prolonged submergence followed by desubmergence, and seven traits (score, water content, Fv/Fm, and concentrations of nitrate, chlorophyll, protein, and starch) were quantified to characterize their acclimation responses. These traits showed substantial variation across the range of accessions. A total of 35 highly significant single-nucleotide polymorphisms (SNPs) were identified across the 20 GWA datasets, pointing to 22 candidate genes, with functions in TCA cycle, DNA modification, and cell division. Detailed functional characterization of one candidate gene, ACONITASE3 (ACO3), was performed. Chromatin immunoprecipitation followed by sequencing showed that a single nucleotide polymorphism in the ACO3 promoter co-located with the binding site of the master regulator of retrograde signaling ANAC017, while subcellular localization of an ACO3-YFP fusion protein confirmed a mitochondrial localization during submergence. Analysis of mutant and overexpression lines determined changes in trait parameters that correlated with altered submergence tolerance and were consistent with the GWAS results. Subsequent RNA-seq experiments suggested that impairing ACO3 function increases the sensitivity to submergence by altering ethylene signaling, whereas ACO3 overexpression leads to tolerance by metabolic priming. These results indicate that ACO3 impacts submergence tolerance through integration of carbon and nitrogen metabolism via the mitochondrial TCA cycle and impacts stress signaling during acclimation to stress.Peer reviewe