19,693 research outputs found
DAF-16 target identification in C. elegans: past, present and future
No full textIn C. elegans , mutations in the conserved insulin/IGF-1 signaling (IIS) pathway lead to a robust extension in lifespan, improved late life health, and protection from age-related disease. These effects are mediated by the FoxO transcription factor DAF-16 which lies downstream of the IIS kinase cascade. Identifying and functionally testing DAF-16 target genes has been a focal point of ageing research for the last 10 years. Here, I review the recent advances in identifying and understanding IIS/DAF-16 targets. These studies continue to reveal the intricate nature of the IIS/DAF-16 gene regulation network and are helping us to understand the mechanisms that control lifespan. Ageing and age related disease is an area of intense public interest, and the biochemical charac- terization of the genes involved will be critical for identifying drugs to improve the health of our ageing population
Long-term starvation and ageing induce AGE-1/PI 3-kinase-dependent translocation of DAF-16/FOXO to the cytoplasm
No full textBackground
The provision of stress resistance diverts resources from development and reproduction and must therefore be tightly regulated. In Caenorhabditis elegans, the switch to increased stress resistance to promote survival through periods of starvation is regulated by the DAF-16/FOXO transcription factor. Reduction-of-function mutations in AGE-1, the C. elegans Class IA phosphoinositide 3-kinase (PI3K), increase lifespan and stress resistance in a daf-16 dependent manner. Class IA PI3Ks downregulate FOXOs by inducing their translocation to the cytoplasm. However, the circumstances under which AGE-1 is normally activated are unclear. To address this question we used C. elegans first stage larvae (L1s), which when starved enter a developmentally-arrested diapause stage until food is encountered.
Results
We find that in L1s both starvation and daf-16 are necessary to confer resistance to oxidative stress in the form of hydrogen peroxide. Accordingly, DAF-16 is localised to cell nuclei after short-term starvation. However, after long-term starvation, DAF-16 unexpectedly translocates to the cytoplasm. This translocation requires functional age-1. H2O2 treatment can replicate the translocation and induce generation of the AGE-1 product PIP3. Because feeding reduces to zero in ageing adult C. elegans, these animals may also undergo long-term starvation. Consistent with our observation in L1s, DAF-16 also translocates to the cytoplasm in old adult worms in an age-1-dependent manner.
Conclusion
DAF-16 is activated in the starved L1 diapause. The translocation of DAF-16 to the cytoplasm after long-term starvation may be a feedback mechanism that prevents excessive expenditure on stress resistance. H2O2 is a candidate second messenger in this feedback mechanism. The lack of this response in age-1(hx546) mutants suggests a novel mechanism by which this mutation increases longevity
Kompetenzen in DaF/DaZ
No full textCompetence orientation opens up always new perspectives for teaching German as an Foreign and as a second language (DaF/DaZ) . The current tendencies of competence orientation presented here are include: - Specialist language skills in the fields of theology and medicine, - the expertise of teachers in relation to learning styles, Grammar and Intercultural Competence as well as - two contrasting analyses of the speech act of the written complaint and oral criticism. Without exception, the authors are enthusiastic and inspiring Teachers who are at the same time committed and open to new challenges, going the extra mile in research. The result of this close interaction of theory and practice are research results with direct application orientation. This is the claim of the series "DaF/DaZ in research and teaching". Christina Maria Ersch has studied German and Scandinavian Studies in Göttingen and German as a foreign language in Mainz, where she works as an academic employee. She has been teaching for several years DaF, is a certified telc examiner and teaches professional training courses on neurodidactics and action-oriented learning. Her research interests include the general didactics with focus on practical competence orientation and the intercultural communication. Die Kompetenzorientierung eröffnet gerade für das Fach Deutsch als Fremd- und Zweitsprache (DaF/DaZ) immer wieder neue Perspektiven für die Lehre. Die hier vorgestellten aktuellen Tendenzen der Kompetenzorientierung umfassen: • fachspezifische Sprachkompetenzen für die Bereiche Theologie und Medizin, • die Fachkompetenzen von Lehrkräften in Bezug auf Lernstile, Grammatik und Interkulturelle Kompetenz sowie • zwei kontrastive Analysen des Sprechaktes der schriftlichen Beschwerde und der mündlichen Kritikäußerung. Die Autorinnen sind ohne Ausnahme begeisterte und begeisternde Lehrkräfte und Dozentinnen, die gleichzeitig engagiert und offen neue Wege in der Forschung gehen. Das Ergebnis dieser engen Verzahnung von Theorie und Praxis sind Forschungsergebnisse mit direkter Anwendungsorientierung. Das ist der Anspruch der Reihe DaF/DaZ in Forschung und Lehre. Christina Maria Ersch hat Germanistik und Skandinavistik in Göttingen und Deutsch als Fremdsprache in Mainz studiert, wo sie als wissenschaftliche Mitarbeiterin tätig ist. Sie unterrichtet seit mehreren Jahren DaF, ist zertifizierte telc-Prüferin und leitet Weiterbildungskurse zu Neurodidaktik und Handlungsorientiertem Lernen. Ihre Forschungsinteressen liegen u. a. in der allgemeinen Didaktik mit Fokus auf praktischer Kompetenzorientierung und der interkulturellen Kommunikation
DAF-2B protein is secreted in starved L1 larvae.
No full text(A) Schematic illustrating the location of mScarlet insertion into the daf-2 genomic locus. (B) Representative image showing localization of DAF-2B::mScarlet protein in coelomocytes marked with unc-122p::GFP in starved L1 larvae. Yellow arrow indicates DAF-2B::mScarlet in coelomocyte. Images were taken at 63x magnification.</p
DAF-16 FOXO localizes to vesicles in intestinal cells.
No full textRepresentative confocal and differential interference contrast (DIC) images of intestinal cells of wild-type (A-C, G-I, M-O and S-U) and tbc-2(tm2241) (D-F, J-L, P-R and V-X) animals expressing DAF-16::GFP daf-16(hq23) (A-F), muIs71 GFP::DAF-16a (G-L), lpIs12 DAF-16a::RFP (M-R) and lpIs14 DAF-16f::GFP (S-X). Endogenously tagged DAF-16::GFP daf-16(hq23) is present on vesicles in both wild-type and tbc-2(tm2241) intestinal cells (A and D arrowheads). Arrows mark bright autofluorescent lysosome-related organelles that bleed through the GFP channel in these lower expressing strains. Vesicular localization of GFP::DAF-16a (G and J), DAF-16a::RFP (M and P) and DAF-16f::GFP (S and V) was only seen in tbc-2(tm2241) animals and not visible in wild-type backgrounds. Scale bars (A, G, M, S), 10μm. (TIF)</p
Kompetenzen in DaF/DaZ
No full textCompetence orientation opens up always new perspectives for teaching German as an Foreign and as a second language (DaF/DaZ) . The current tendencies of competence orientation presented here are include: - Specialist language skills in the fields of theology and medicine, - the expertise of teachers in relation to learning styles, Grammar and Intercultural Competence as well as - two contrasting analyses of the speech act of the written complaint and oral criticism. Without exception, the authors are enthusiastic and inspiring Teachers who are at the same time committed and open to new challenges, going the extra mile in research. The result of this close interaction of theory and practice are research results with direct application orientation. This is the claim of the series "DaF/DaZ in research and teaching". Christina Maria Ersch has studied German and Scandinavian Studies in Göttingen and German as a foreign language in Mainz, where she works as an academic employee. She has been teaching for several years DaF, is a certified telc examiner and teaches professional training courses on neurodidactics and action-oriented learning. Her research interests include the general didactics with focus on practical competence orientation and the intercultural communication. Die Kompetenzorientierung eröffnet gerade für das Fach Deutsch als Fremd- und Zweitsprache (DaF/DaZ) immer wieder neue Perspektiven für die Lehre. Die hier vorgestellten aktuellen Tendenzen der Kompetenzorientierung umfassen: • fachspezifische Sprachkompetenzen für die Bereiche Theologie und Medizin, • die Fachkompetenzen von Lehrkräften in Bezug auf Lernstile, Grammatik und Interkulturelle Kompetenz sowie • zwei kontrastive Analysen des Sprechaktes der schriftlichen Beschwerde und der mündlichen Kritikäußerung. Die Autorinnen sind ohne Ausnahme begeisterte und begeisternde Lehrkräfte und Dozentinnen, die gleichzeitig engagiert und offen neue Wege in der Forschung gehen. Das Ergebnis dieser engen Verzahnung von Theorie und Praxis sind Forschungsergebnisse mit direkter Anwendungsorientierung. Das ist der Anspruch der Reihe DaF/DaZ in Forschung und Lehre. Christina Maria Ersch hat Germanistik und Skandinavistik in Göttingen und Deutsch als Fremdsprache in Mainz studiert, wo sie als wissenschaftliche Mitarbeiterin tätig ist. Sie unterrichtet seit mehreren Jahren DaF, ist zertifizierte telc-Prüferin und leitet Weiterbildungskurse zu Neurodidaktik und Handlungsorientiertem Lernen. Ihre Forschungsinteressen liegen u. a. in der allgemeinen Didaktik mit Fokus auf praktischer Kompetenzorientierung und der interkulturellen Kommunikation
DAF-16 isoforms act in ASER during taste avoidance learning.
No full text(A) The genomic structures of DAF-16 isoforms and mutation sites of deletion mutants are shown. (B, C) Salt chemotaxis after high-salt conditioning in the absence of food. Each dot in red represents a chemotaxis index obtained from each trial. Each daf-16 isoform cDNA was expressed in daf-16(mgDf50) mutant animals by its own promoter or the ASER-specific gcy-5 promoter (B; N = 7 or 8). DAF-16a isoform was expressed by the H20, odr-4, ges-1, myo-3, and dpy-7 promoter, which drove expression in most or all neurons, amphid and phasmid sensory neurons except ASE and AFD, intestine, muscle, and hypodermis, respectively (C; N = 8 or 9). (D, E) Salt chemotaxis of daf-16 mutants carrying deletions in isoform-specific exon after high- (D) or low-salt (E) conditioning without food (N = 9). (A, B, D, E) Error bars indicate SEM. Dunnett’s test following one-way ANOVA, *p < 0.05, **p < 0.01, and ***p < 0.001. (F) Schematic of auxin-dependent expression of DAF-16 in ASER using degron-tagged DAF-16 and auxin interactive protein (TIR1). Auxin (IAA) induces ubiquitin (Ub)-dependent degradation of degron-tagged DAF-16. Animals are grown to the adult without auxin and then auxin was added for two hours before conditioning and during conditioning. (G) Salt chemotaxis of animals carrying transgenes after high-salt conditioning in the absence of food (N = 7). A green or purple dot represents a chemotaxis index obtained from each trial when treated with either the solvent, 0.25% ethanol or 1 mM auxin, respectively. Two lines of transgenic animals were tested. Error bars indicate SEM. Bonferroni multiple test following two-way ANOVA, ***p < 0.001.</p
DAF-7/TGF-β protein function is disrupted in <i>daf-28</i> mutant animals.
No full textA. Fluorescent and transmitted light micrographs of late L1 larvae of the indicated genotypes, carrying SMAD::GFP (cuIs5) transgene. Bright fluorescence in the pharynx indicates DAF-7 activity. Animals were picked under transmitted light to provide an unbiased sample. Left panels correspond to boxed areas showing fluorescent pharynxes. B. Box-and-whisker plot of GFP intensity in animals of indicated genotypes (n = 1351, 770, and 118 animals, respectively; L1/L2 animals) carrying the SMAD::GFP transgene. Boxes show interquartile range, whiskers are 1-99th percentile. The outliers are shown as individual data points outside the whisker range. C. Development of sa191 animals with bright vs. dim SMAD::GFP fluorescence. Decreased reporter activity correlates with stronger activation of dauer signaling (χ2 = 38.81, df = 2). Animals were separated into dim and bright populations by eye using fluorescent stereo microscope. D. Over-expression of DAF-7 cDNA in the ASI neuron (ASI::DAF-7) (χ2 = 81.71, df = 2) or expression of mCherry::DAF-7 fusion protein (χ2 = 427.3, df = 2) rescues sa191 dauer phenotype at 20°C. Since this is a non-integrated transgene, non-transgenic siblings (N-Tg sib.) were used as internal controls. 4xDel strain lacks four pro-growth IGF-like proteins, including DAF-28, INS-4 and INS-6. E. mCherry::DAF-7 fusion protein expressed from its cognate promoter rescues daf-7(e1372) loss-of-function mutation at 20°C. Non-transgenic siblings (N-Tg sib.) in the first generation only are also rescued. Data in B were analyzed by ANOVA followed by Bonferroni’s multiple comparison test, α = 0.05, ****PPP<0.0001.</p
DAF-16 FOXO endosome localization is regulated by IIS and nutrient availability.
No full text(A) Bar graphs of the percent wild-type (black) and tbc-2(tm2241) (red) animals with DAF-16a::GFP (zIs356) vesicles in fed animals, animals starved between 4 and 5 hours and starved animals that have been refed for 1 to 2 hours. (B) Diagram of IIS-mediate regulation of DAF-16/FOXO. (C) Grouped bar graphs quantifying the percentage of wild-type and daf-2(e1370) L4 larvae (cumulative data from 3 independent strains) with 0, 1–10, 11–50 or >50 DAF-16a::GFP (zIs356) positive vesicles at 15°C or shifted overnight to 25°C. (D) Bar graphs of percent wild-type and daf-18(e1375) (cumulative data from 3 independent strains) and daf-18(ok480) (cumulative data from 5 independent strains) with DAF-16a::GFP (zIs356) vesicles. (E) Bar graphs of percent wild-type and akt-2(ok393) (cumulative data from 2 independent strains) with DAF-16a::GFP (zIs356) vesicles. (F) Bar graphs of percent wild-type animals treated with control empty vector RNAi and akt-1(RNAi) with DAF-16a::GFP (zIs356) vesicles. (G) Bar graphs of percent wild-type, sgk-1(ok538) and sgk-1(ft15) with DAF-16a::GFP (zIs356) vesicles. (H) Bar graphs of the percent wild-type (black) and tbc-2(tm2241) (red) animals fed control empty vector RNAi, par-5(RNAi) and ftt-2(RNAi) with DAF-16a::GFP (zIs356) vesicles. (I) Bar graph of the precent tbc-2(tm2241) animals with GFP::DAF-16a (muIs71) or DAF-16aAM::GFP (muIs113)-positive vesicles. Raw data is available in S1 Data. Representative images of GFP::DAF-16a (muIs71) (top) and DAF-16aAM::GFP (muIs113) (bottom) are shown. GFP::DAF-16a vesicles (arrows) and the nuclei (n). Fisher’s exact test (graphpad.com) was used to determine the statistical difference between conditions. n, total number of animals. ns, not significant, * P.05, ** P.01, *** P.001, **** P.0001.</p
DAF-16 FOXO localizes to vesicles in intestinal cells.
No full text(A-H) Representative confocal and differential interference contrast (DIC) images of an intestinal cell of wild-type (A, C, E, G) and tbc-2(tm2241) (B, D, F, H) animals expressing DAF-16a::GFP (zIs356). DAF-16a::GFP (green) is present on vesicles in both wild-type and tbc-2(tm2241) intestinal cells (A and B) that are positive for autofluorescence (blue) present in the the endolysosomal system (E and F). Corresponding DIC (C and D) and merged (G and H) images are shown. A representative vesicle is shown (arrow head) and the two nuclei of the binucleate cell are marked (n). Note that DAF-16a::GFP is excluded from the large nucleoli (A). (I-J) Grouped bar graphs quantifying the percentage of wild-type (I) and tbc-2(tm2241) (J) animals with 0, 1–10, 11–50 or >50 DAF-16a::GFP (zIs356) positive vesicles at the different larval stages (L1-4) or 1 and 3 day old adults (A1 and A3). Raw data is available in S1 Data. (K) A Tukey boxplot of the nuclear intensity in artificial units (a.u.) of DAF-16a::GFP in tbc-2(tm2241) intestinal cells with and without DAF-16a::GFP positive vesicles. Raw data is available in S1 Data. n, total number of animals *** P.001 in an unpaired t test (Prism 8). Scale bar (A), 10μm.</p
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