Seed-coat protective neolignans are produced by the dirigent protein AtDP1 and the laccase AtLAC5 in Arabidopsis

種子を保護するネオリグナンの生合成機構を解明 --新たな薬効成分の創出に期待--. 京都大学プレスリリース. 2020-12-03.Lignans/neolignans are generally synthesized from coniferyl alcohol (CA) in the cinnamate/monolignol pathway by oxidation to generate the corresponding radicals with subsequent stereoselective dimerization aided by dirigent proteins (DIRs). Genes encoding oxidases and DIRs for neolignan biosynthesis have not been identified previously. In Arabidopsis thaliana, the DIR AtDP1/AtDIR12 plays an essential role in the 8-O-4′ coupling in neolignan biosynthesis by unequivocal structural determination of the compound missing in the atdp1 mutant as a sinapoylcholine (SC)-conjugated neolignan, erythro-3-{4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-hydroxymethylethoxy]-3, 5-dimethoxyphenyl}acryloylcholine. Phylogenetic analyses showed that AtDP1/AtDIR12 belongs to the DIR-a subfamily composed of DIRs for 8-8′ coupling of monolignol radicals. AtDP1/AtDIR12 is specifically expressed in outer integument 1 cells in developing seeds. As a putative oxidase for neolignan biosynthesis, we focused on AtLAC5, a laccase gene coexpressed with AtDP1/AtDIR12. In lac5 mutants, the abundance of feruloylcholine (FC)-conjugated neolignans decreased to a level comparable to those in the atdp1 mutant. In addition, SC/FC-conjugated neolignans were missing in the seeds of mutants defective in SCT/SCPL19, an enzyme that synthesizes SC. These results strongly suggest that AtDP1/AtDIR12 and AtLAC5 are involved in neolignan biosynthesis via SC/FC. A tetrazolium penetration assay showed that seed coat permeability increased in atdp1 mutants, suggesting a protective role of neolignans in A. thaliana seeds

Ligand-binding properties and subcellular localization of maize cytokinin receptors

The ligand-binding properties of the maize (Zea mays L.) cytokinin receptors ZmHK1, ZmHK2, and ZmHK3a have been characterized using cytokinin binding assays with living cells or membrane fractions. According to affinity measurements, ZmHK1 preferred N6-(Δ2-isopentenyl)adenine (iP) and had nearly equal affinities to trans-zeatin (tZ) and cis-zeatin (cZ). ZmHK2 preferred tZ and iP to cZ, while ZmHK3a preferred iP. Only ZmHK2 had a high affinity to dihydrozeatin (DZ). Analysis of subcellular fractions from leaves and roots of maize seedlings revealed specific binding of tZ in the microsome fraction but not in chloroplasts or mitochondria. In competitive binding assays with microsomes, tZ and iP were potent competitors of [3H]tZ while cZ demonstrated significantly lower affinity; adenine was almost ineffective. The binding specificities of microsomes from leaf and root cells for cytokinins were consistent with the expression pattern of the ZmHKs and our results on individual receptor properties. Aqueous two-phase partitioning and sucrose density-gradient centrifugation followed by immunological detection with monoclonal antibody showed that ZmHK1 was associated with the endoplasmic reticulum (ER). This was corroborated by observations of the subcellular localization of ZmHK1 fusions with green fluorescent protein in maize protoplasts. All these data strongly suggest that at least a part of cytokinin perception occurs in the ER

Predicting complete loss to follow-up after a health-education program: number of absences and face-to-face contact with a researcher

<p>Abstract</p> <p>Background</p> <p>Research on health-education programs requires longitudinal data. Loss to follow-up can lead to imprecision and bias, and <it>complete </it>loss to follow-up is particularly damaging. If that loss is predictable, then efforts to prevent it can be focused on those program participants who are at the highest risk. We identified predictors of complete loss to follow-up in a longitudinal cohort study.</p> <p>Methods</p> <p>Data were collected over 1 year in a study of adults with chronic illnesses who were in a program to learn self-management skills. Following baseline measurements, the program had one group-discussion session each week for six weeks. Follow-up questionnaires were sent 3, 6, and 12 months after the baseline measurement. A person was classified as completely lost to follow-up if none of those three follow-up questionnaires had been returned by two months after the last one was sent.</p> <p>We tested two hypotheses: that complete loss to follow-up was directly associated with the number of absences from the program sessions, and that it was less common among people who had had face-to-face contact with one of the researchers. We also tested predictors of data loss identified previously and examined associations with specific diagnoses.</p> <p>Using the unpaired t-test, the U test, Fisher's exact test, and logistic regression, we identified good predictors of complete loss to follow-up.</p> <p>Results</p> <p>The prevalence of complete loss to follow-up was 12.2% (50/409). Complete loss to follow-up was directly related to the number of absences (odds ratio; 95% confidence interval: 1.78; 1.49-2.12), and it was inversely related to age (0.97; 0.95-0.99). Complete loss to follow-up was less common among people who had met one of the researchers (0.51; 0.28-0.95) and among those with connective tissue disease (0.29; 0.09-0.98). For the multivariate logistic model the area under the ROC curve was 0.77.</p> <p>Conclusions</p> <p>Complete loss to follow-up after this health-education program can be predicted to some extent from data that are easy to collect (age, number of absences, and diagnosis). Also, face-to-face contact with a researcher deserves further study as a way of increasing participation in follow-up, and health-education programs should include it.</p

Development of a Shortened Version of the Nurse Managers’ Empowering Behavioral Scale for Staff Nurses

The original version of the Nurse Managers’ Empowering Behavioral Scale for Staff Nurses (NMEB-SN) was both unique and comprehensive. However, it was considered lengthy. Hence, the intention of this particular study was to develop a shortened version of the NMEB-SN comprising 15 items across five subscales. Responses from 1268 staff nurses working at 10 Japanese hospitals were included in the analysis to confirm the validity and reliability of the scale. The results ensured internal consistency, construct and criterion-related validity, and test–retest reliability. The NMEB-SN short version is applicable in the context of practical and efficient nursing management to attract more nurses to the workplace