37,268 research outputs found
Perturbation of cytokinin and ethylene-signalling pathways explain the strong rooting phenotype exhibited by Arabidopsis expressing the Schizosaccharomyces pombe mitotic inducer, cdc25
No full textBackground
Entry into mitosis is regulated by cyclin dependent kinases that in turn are phosphoregulated. In most eukaryotes, phosphoregulation is through WEE1 kinase and CDC25 phosphatase. In higher plants a homologous CDC25 gene is unconfirmed and hence the mitotic inducer Schizosaccharomyces pombe (Sp) cdc25 has been used as a tool in transgenic plants to probe cell cycle function. Expression of Spcdc25 in tobacco BY-2 cells accelerates entry into mitosis and depletes cytokinins; in whole plants it stimulates lateral root production. Here we show, for the first time, that alterations to cytokinin and ethylene signaling explain the rooting phenotype elicited by Spcdc25 expression in Arabidopsis.
Results
Expressing Spcdc25 in Arabidopsis results in increased formation of lateral and adventitious roots, a reduction of primary root width and more isodiametric cells in the root apical meristem (RAM) compared with wild type. Furthermore it stimulates root morphogenesis from hypocotyls when cultured on two way grids of increasing auxin and cytokinin concentrations. Microarray analysis of seedling roots expressing Spcdc25 reveals that expression of 167 genes is changed by > 2-fold. As well as genes related to stress responses and defence, these include 19 genes related to transcriptional regulation and signaling. Amongst these was the up-regulation of genes associated with ethylene synthesis and signaling. Seedlings expressing Spcdc25 produced 2-fold more ethylene than WT and exhibited a significant reduction in hypocotyl length both in darkness or when exposed to 10 ppm ethylene. Furthermore in Spcdc25 expressing plants, the cytokinin receptor AHK3 was down-regulated, and endogenous levels of iPA were reduced whereas endogeous IAA concentrations in the roots increased.
Conclusions
We suggest that the reduction in root width and change to a more isodiametric cell phenotype in the RAM in Spcdc25 expressing plants is a response to ethylene over-production. The increased rooting phenotype in Spcdc25 expressing plants is due to an increase in the ratio of endogenous auxin to cytokinin that is known to stimulate an increased rate of lateral root production. Overall, our data reveal important cross talk between cell division and plant growth regulators leading to developmental changes
Interactions between plant cell cycle genes and plant growth regulators. Expression of Spcdc25 and Wee1 in Arabidopsis alters the response of hypocotyl explants to auxin & cytokinin in culture
No full textExpression of Spcdc25 in Arabidopsis alters the response of hypocotyl explants to auxin & cytokinin in culture
No full textThe eukaryotic cell cycle comprises four distinct phases, mitosis (M), G1, DNA synthesis (S)-phase and G2 in which the key transitions are G1/S and G2/M. Progression of dividing cells through the cell cycle is controlled by key enzymes: cyclin-dependent kinases (CDKs), the products of cdc2-like genes. The regulation of CDK activity includes, amongst others, its activation by Cdc25 phosphatase at G2/M. This positive regulator is balanced by negative regulation by a protein kinase encoded by wee1. A plant homologue of the inactivating kinase, wee1, has already been cloned. However, a homologue of the activating phosphatase cdc25 has not been unequivocally identified in plants yet. The expression of cdc2-like genes can be influenced by many factors including plant growth regulators, mainly auxins and cytokinins. Expressing the fission yeast cdc25 (Spcdc25) in the tobacco BY2 cell line results in cells bypassing a cytokinin block, and in explants of tobacco expressing Spcdc25, shoot development is stimulated not only in a treatment that favours shoot formation (high cytokinin and low auxin) but also under root-stimulating conditions (high auxin and low cytokinin) and even without exogenous growth regulator treatment. Wild type Arabidopsis hypocotyls explants respond to increasing levels of cytokinin with rapid proliferation, greening and formation of shoots, but are unable to form shoots in the absence of auxin and cytokinin. We tested if hypocotyl explants from Arabidopsis transformed with constitutive and inducible lines Spcdc25 respond like wt to auxin (NAA) and cytokinin (Kinetin) in a system of grids in which we increase concentration of these exogenous plant growth regulators. We find that Wt and Spcdc25 hypocotiles segments are very sensible to higher liveles of ormons (1000 ngml-1 to 3000 ngml-1), calli grew with a lot of root hairs and the analysis of shots formation was impossible. Also is required a minimum level of NAA for calli induction in these strains: at 25 ngml-1 NAA/Kinetin we start to see grow of calli in Spcdc25 lines, plants in WT, not grow in not induced Spcdc25 line. Interesting results at 25, 50 ngml-1 NAA and 200ngml-1 Kinetin where in Spcdc25 there is grow of real roots, not visible in wt and not induced Spcdc25 line. At several concentrations of hormones Spcdc25 forms buds they will be show and discussed
Expression of Spcdc25 in Arabidopsis alters the response of hypocotyl explants to auxin & cytokinin in culture
No full textThe eukaryotic cell cycle comprises four distinct phases, mitosis (M), G1, DNA synthesis (S)-phase and G2 in which the key transitions are G1/S and G2/M. Progression of dividing cells through the cell cycle is controlled by key enzymes: cyclin-dependent kinases (CDKs), the products of cdc2-like genes. The regulation of CDK activity includes, amongst others, its activation by Cdc25 phosphatase at G2/M. This positive regulator is balanced by negative regulation by a protein kinase encoded by wee1. A plant homologue of the inactivating kinase, wee1, has already been cloned. However, a homologue of the activating phosphatase cdc25 has not been unequivocally identified in plants yet. The expression of cdc2-like genes can be influenced by many factors including plant growth regulators, mainly auxins and cytokinins. Expressing the fission yeast cdc25 (Spcdc25) in the tobacco BY2 cell line results in cells bypassing a cytokinin block, and in explants of tobacco expressing Spcdc25, shoot development is stimulated not only in a treatment that favours shoot formation (high cytokinin and low auxin) but also under root-stimulating conditions (high auxin and low cytokinin) and even without exogenous growth regulator treatment. Wild type Arabidopsis hypocotyls explants respond to increasing levels of cytokinin with rapid proliferation, greening and formation of shoots, but are unable to form shoots in the absence of auxin and cytokinin. We tested if hypocotyl explants from Arabidopsis transformed with constitutive and inducible lines Spcdc25 respond like wt to auxin (NAA) and cytokinin (Kinetin) in a system of grids in which we increase concentration of these exogenous plant growth regulators. We find that Wt and Spcdc25 hypocotiles segments are very sensible to higher liveles of ormons (1000 ngml-1 to 3000 ngml-1), calli grew with a lot of root hairs and the analysis of shots formation was impossible. Also is required a minimum level of NAA for calli induction in these strains: at 25 ngml-1 NAA/Kinetin we start to see grow of calli in Spcdc25 lines, plants in WT, not grow in not induced Spcdc25 line. Interesting results at 25, 50 ngml-1 NAA and 200ngml-1 Kinetin where in Spcdc25 there is grow of real roots, not visible in wt and not induced Spcdc25 line. At several concentrations of hormones Spcdc25 forms buds they will be show and discusse
Over expression of Spcdc25 and of ATWEE1 in Arabidopsis alter the sensitivity of hypocotyl explants to auxin and cytokinin in culture
No full textThe cell cycle is regulated by plant growth regulators (PGRs), mainly auxins and cytokinins. In eukaryotes, two genes regulate entry into mitosis: cdc25 and wee1, although a confirmed homologue of cdc25 in plants has not yet been identified. Expressing the fission yeast cdc25 (Spcdc25) in tobacco BY2 cells allows them to bypass a cytokinin block at G2/M. In tobacco and Arabidopsis roots, Spcdc25 expression led to an increased frequency of lateral roots. Conversely, over-expression of AtWEE1 in Arabidopsis induces a slower rate of root elongation and a reduced frequency of lateral roots. Wild type Arabidopsis hypocotyl explants respond to increasing levels of cytokinin with rapid proliferation, greening and formation of shoots, but are unable to form shoots in the absence of auxin and cytokinin. We tested if hypocotyl explants from Arabidopsis lines over-expressing ATWEE1 and Spcdc25 respond like WT to auxin (NAA) and cytokinin (Kinetin). We used a system of two-way grids in which we increased concentration of NAA and kinetin in X- and Y-axes, respectively. There were clear differences in the response between the transgenic and WT. All concentrations of auxin and cytokinin suppressed growth of calli in the AtWEE1OE line compared to WT. Moreover, in the AtWEE1OE, both organogenesis and formation of root hair structures were suppressed. At higher PGR levels neither WT nor Spcdc25 lines produced shoots but both produced roots and hairs. A minimum level of NAA was required for callus induction in both WT and Spcdc25 lines. However at low NAA/Kinetin there was growth of calli and more roots in Spcdc25 lines compared with WT. In an inducible Spcdc25 line plus inducer, roots formed at concentrations which suppressed roots in the inducible Spcdc25 line without inducer These results are discussed in the context of plant growth regulators and regulatory genes of the plant cell cycle
Using volatile organic compounds to monitor shelf-life in rocket salad
No full textRocket salad (Diplotaxis tenuifolia or Eruca sativa) is a perishable product of
increasing interest due to its high content of nutritionally relevant compounds
including glucosinolates and vitamin C. There is an increasing consumption of readyto-
eat salads which are sold to the consumer in bags, often packed under modified
atmosphere. Shelf-life and sell-by dates are commonly applied to these products and
are usually dictated by the appearance of the product rather than its nutritional value.
During shelf-life, postharvest deterioration leads to a loss of nutritionally relevant
compounds such as vitamin C. This is accelerated by suboptimal conditions during
storage and transport such as breaches of the cold-chain. Volatile organic compounds
(VOCs) are easy and quick to sample use of thermal desorption gas chromatography
time of flight mass spectroscopy (TD-GC-TOF-MS) enables remote sampling and a very
sensitive analysis of VOC profiles. We have used TD-GC-TOF-MS to sample VOCs from
rocket salad bags sourced from a local supermarket to assess changes during the
shelf-life of the product. Using statistical analyses that treat the whole VOC profile as a
single variable we show that it is possible to differentiate between day of purchase,
use by date and time points beyond sale. We conclude that this methodology is
therefore of use for assessing rocket salad quality through the supply chain
Association between inherited thrombophilia and venous thromboembolism in patients with non‐O blood type: a meta‐analysis
No full textINTROduCTION Hereditary conditions, including non‐O blood group or thrombophilic alterations such as factor V Leiden (FVL) and G20210A prothrombin mutation (G20210A PTM), are usually considered risk factors for venous thromboembolism (VTE). ObjECTIvEs This meta‐analysis was carried out to find out if simultaneous occurrence of FVL or PTM and the non‐O blood group may increase the risk of developing VTE. PATIENTs ANd mEThOds MEDLINE and EMBASE databases were explored until March 2021. Eleven publications, comprising 82 465 patients, and 6 studies, including 70 004 patients, were analyzed to evaluate the association between FVL/non‐O group and PTM/non‐O group, respectively. Pooled odds ratios (OR) and 95% CIs were obtained by a random‐effects model. REsuLTs Nearly 6% of the enrolled patients manifested both FVL and the non‐O group, whereas only 1.4% had PTM and the non‐O group. The VTE risk was considerably amplified in FVL and the non‐O group (OR, 5.94; 95% CI, 5.33–6.61; P <0.01), more than if just 1 of these 2 risk factors was present. The equivalent population attributable risk (PAR) of VTE was around 21%. The patients with PTM and the non‐O group manifested a significantly augmented risk of VTE (OR, 4.01; 95% CI, 3.00–5.36; P = 0.01), although PAR was considerably lower (3.7%). CONCLusIONs The co‐occurrence of FVL and the non‐O group enhances the risk of VTE that could have clinical influence and drive therapeutic corrections. The coexistence of PTM and the non‐O blood group seems to play a less important role in the incidence of VTE
Biochemical and molecular changes in peach fruit exposed to cold stress conditions
No full text: Storage or transportation temperature is very important for preserving the quality of fruit. However, low temperature in sensitive fruit such as peach can induce loss of quality. Fruit exposed to a specific range of temperatures and for a longer period can show chilling injury (CI) symptoms. The susceptibility to CI at low temperature varies among cultivars and genetic backgrounds. Along with agronomic management, appropriate postharvest management can limit quality losses. The importance of correct temperature management during postharvest handling has been widely demonstrated. Nowadays, due to long-distance markets and complex logistics that require multiple actors, the management of storage/transportation conditions is crucial for the quality of products reaching the consumer.Peach fruit exposed to low temperatures activate a suite of physiological, metabolomic, and molecular changes that attempt to counteract the negative effects of chilling stress. In this review an overview of the factors involved, and plant responses is presented and critically discussed. Physiological disorders associated with CI generally only appear after the storage/transportation, hence early detection methods are needed to monitor quality and detect internal changes which will lead to CI development. CI detection tools are assessed: they need to be easy to use, and preferably non-destructive to avoid loss of products
6-[1-(2,6-Difluorophenyl)ethyl]pyrimidinones Antagonize Cell Proliferation and Induce Cell Differentiation by Inhibiting (a Non Telomeric) Endogenous Reverse Transcriptase
No full textTwo 2,6-difluoro-DABO derivatives (MC 1047, 1, and MC 1220, 2, respectively) were tested against endogenous, nontelomeric reverse transcriptase (endo-RT) in human differentiating cell systems to investigate their antiproliferative and cytodifferentiating activity. The two compounds significantly reduced cell proliferation and facilitated the morphological differentiation of cells. These results propose F-2-DABOs as useful tools in preventive and/or curative therapy to counteract the loss of differentiation in dedifferentiating pathologies and as antiproliferative drugs in tumor therapy
1ST MEASUREMENT OF GAMMA(D(S)(+)-]MU+NU)/GAMMA(D(S)(+)-]PHI-PI+)
No full textComplete Author List:
ACOSTA D, ATHANAS M, MASEK G, PAAR H, BEAN A, GRONBERG J, KUTSCHKE R, MENARY S, MORRISON RJ, NAKANISHI S, NELSON HN, NELSON TK, RICHMAN JD, RYD A, TAJIMA H, SCHMIDT D, SPERKA D, WITHERELL MS, PROCARIO M, YANG S, BALEST R, CHO K, DAOUDI M, FORD WT, JOHNSON DR, LINGEL K, LOHNER M, RANKIN P, SMITH JG, ALEXANDER JP, BEBEK C, BERKELMAN K, BESSON D, BROWDER TE, CASSEL DG, CHO HA, COFFMAN DM, DRELL PS, EHRLICH R, GALIK RS, GARCIASCIVERES M, GEISER B, GITTELMAN B, GRAY SW, HARTILL DL, HELTSLEY BK, JONES CD, JONES SL, KANDASWAMY J, KATAYAMA N, KIM PC, KREINICK DL, LUDWIG GS, MASUI J, MEVISSEN J, MISTRY NB, NG CR, NORDBERG E, OGG M, PATTERSON JR, PETERSON D, RILEY D, SALMAN S, SAPPER M, WORDEN H, WURTHWEIN F, AVERY P, FREYBERGER A, RODRIGUEZ J, STEPHENS R, YELTON J, CINABRO D, HENDERSON S, KINOSHITA K, LIU T, SAULNIER M, SHEN F, WILSON R, YAMAMOTO H, ONG B, SELEN M, SADOFF AJ, AMMAR R, BALL S, BARINGER P, COPPAGE D, COPTY N, DAVIS R, HANCOCK N, KELLY M, KWAK N, LAM H, KUBOTA Y, LATTERY M, NELSON JK, PATTON S, PERTICONE D, POLING R, SAVINOV V, SCHRENK S, WANG R, ALAM MS, KIM IJ, NEMATI B, ONEILL JJ, SEVERINI H, SUN CR, ZOELLER MM, CRAWFORD G, DAUBENMIER CM, FULTON R, FUJINO D, GAN KK, HONSCHEID K, KAGAN H, KASS R, LEE J, MALCHOW R, MORROW F, SKOVPEN Y, SUNG M, WHITE C, WHITMORE J, WILSON P, BUTLER F, FU X, KALBFLEISCH G, LAMBRECHT M, ROSS WR, SKUBIC P, SNOW J, WANG PL, WOOD M, BORTOLETTO D, BROWN DN, FAST J, MCILWAIN RL, MIAO T, MILLER DH, MODESITT M, SCHAFFNER SF, SHIBATA EI, SHIPSEY IPJ, WANG PN, BATTLE M, ERNST J, KROHA H, ROBERTS S, SPARKS K, THORNDIKE EH, WANG CH, DOMINICK J, SANGHERA S, SHELKOV V, SKWARNICKI T, STROYNOWSKI R, VOLOBOUEV I, ZADOROZHNY P, ARTUSO M, HE D, GOLDBERG M, HORWITZ N, KENNETT R, MONETI GC, MUHEIM F, MUKHIN Y, PLAYFER S, ROZEN Y, STONE S, THULASIDAS M, VASSEUR G, ZHU G, BARTELT J, CSORNA SE, EGYED Z, JAIN V, SHELDON P, AKERIB DS, BARISH B, CHADHA M, CHAN S, COWEN DF, EIGEN G, MILLER JS, OGRADY C, URHEIM J, WEINSTEIN A
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