Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at √s = 13 TeV

Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than 355 GeV and the other top quark decays into ℓνb are presented using 139 fb−1 of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at s = 13 TeV is measured to be σ = 1.267 ± 0.005 ± 0.053 pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of 4.2%. The cross-section is measured differentially as a function of variables characterising the tt¯ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to search for new physics in the context of the effective field theory framework. No significant deviation from the Standard Model is observed and limits are set on the Wilson coefficients of the dimension-six operators OtG and Otq(8), where the limits on the latter are the most stringent to date. [Figure not available: see fulltext.]

Two euAGAMOUS genes control C-function in Medicago truncatula

[EN] C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula.This work was funded by grants BIO2009-08134 and BIO2012-39849-C02-01 from the Spanish Ministry of Economy and Competitiveness and the Ramon y Cajal Program (RYC-2007-00627 to CGM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Serwatowska, J.; Roque Mesa, EM.; Gómez Mena, MC.; Constantin, GD.; Wen, J.; Mysore, KS.; Lund, OS.... (2014). Two euAGAMOUS genes control C-function in Medicago truncatula. PLoS ONE. 9(8):103770-1-103770-12. https://doi.org/10.1371/journal.pone.0103770S103770-1103770-1298Prunet, N., & Jack, T. P. (2013). Flower Development in Arabidopsis: There Is More to It Than Learning Your ABCs. Flower Development, 3-33. doi:10.1007/978-1-4614-9408-9_1Causier, B., Schwarz-Sommer, Z., & Davies, B. (2010). Floral organ identity: 20 years of ABCs. Seminars in Cell & Developmental Biology, 21(1), 73-79. doi:10.1016/j.semcdb.2009.10.005Irish, V. F. (2010). The flowering of Arabidopsis flower development. The Plant Journal, 61(6), 1014-1028. doi:10.1111/j.1365-313x.2009.04065.xHeijmans, K., Morel, P., & Vandenbussche, M. (2012). MADS-box Genes and Floral Development: the Dark Side. Journal of Experimental Botany, 63(15), 5397-5404. doi:10.1093/jxb/ers233Bowman, J. L., Smyth, D. R., & Meyerowitz, E. M. (1989). Genes directing flower development in Arabidopsis. The Plant Cell, 1(1), 37-52. doi:10.1105/tpc.1.1.37Yanofsky, M. F., Ma, H., Bowman, J. L., Drews, G. N., Feldmann, K. A., & Meyerowitz, E. M. (1990). The protein encoded by the Arabidopsis homeotic gene agamous resembles transcription factors. Nature, 346(6279), 35-39. doi:10.1038/346035a0Bradley, D., Carpenter, R., Sommer, H., Hartley, N., & Coen, E. (1993). Complementary floral homeotic phenotypes result from opposite orientations of a transposon at the plena locus of antirrhinum. Cell, 72(1), 85-95. doi:10.1016/0092-8674(93)90052-rPinyopich, A., Ditta, G. S., Savidge, B., Liljegren, S. J., Baumann, E., Wisman, E., & Yanofsky, M. F. (2003). Assessing the redundancy of MADS-box genes during carpel and ovule development. Nature, 424(6944), 85-88. doi:10.1038/nature01741Liljegren, S. J., Ditta, G. S., Eshed, Y., Savidge, B., Bowman, J. L., & Yanofsky, M. F. (2000). SHATTERPROOF MADS-box genes control seed dispersal in Arabidopsis. Nature, 404(6779), 766-770. doi:10.1038/35008089Davies, B., Motte, P., Keck, E., Saedler, H., Sommer, H., & Schwarz-Sommer, Z. (1999). PLENA and FARINELLI: redundancy and regulatory interactions between two Antirrhinum MADS-box factors controlling flower development. The EMBO Journal, 18(14), 4023-4034. doi:10.1093/emboj/18.14.4023Kramer, E. M., Jaramillo, M. A., & Di Stilio, V. S. (2004). Patterns of Gene Duplication and Functional Evolution During the Diversification of the AGAMOUS Subfamily of MADS Box Genes in Angiosperms. Genetics, 166(2), 1011-1023. doi:10.1534/genetics.166.2.1011Becker, A. (2003). The major clades of MADS-box genes and their role in the development and evolution of flowering plants. Molecular Phylogenetics and Evolution, 29(3), 464-489. doi:10.1016/s1055-7903(03)00207-0Irish, V. F. (2003). The evolution of floral homeotic gene function. BioEssays, 25(7), 637-646. doi:10.1002/bies.10292Zahn, L. M., Leebens-Mack, J. H., Arrington, J. M., Hu, Y., Landherr, L. L., dePamphilis, C. W., … Ma, H. (2006). Conservation and divergence in the AGAMOUS subfamily of MADS-box genes: evidence of independent sub- and neofunctionalization events. Evolution Development, 8(1), 30-45. doi:10.1111/j.1525-142x.2006.05073.xFerrandiz, C. (2000). Negative Regulation of the SHATTERPROOF Genes by FRUITFULL During Arabidopsis Fruit Development. Science, 289(5478), 436-438. doi:10.1126/science.289.5478.436Ma, H., Yanofsky, M. F., & Meyerowitz, E. M. (1991). AGL1-AGL6, an Arabidopsis gene family with similarity to floral homeotic and transcription factor genes. Genes & Development, 5(3), 484-495. doi:10.1101/gad.5.3.484Savidge, B., Rounsley, S. D., & Yanofsky, M. F. (1995). Temporal relationship between the transcription of two Arabidopsis MADS box genes and the floral organ identity genes. The Plant Cell, 7(6), 721-733. doi:10.1105/tpc.7.6.721Colombo, M., Brambilla, V., Marcheselli, R., Caporali, E., Kater, M. M., & Colombo, L. (2010). A new role for the SHATTERPROOF genes during Arabidopsis gynoecium development. Developmental Biology, 337(2), 294-302. doi:10.1016/j.ydbio.2009.10.043Fourquin, C., & Ferrándiz, C. (2012). Functional analyses of AGAMOUS family members in Nicotiana benthamiana clarify the evolution of early and late roles of C-function genes in eudicots. The Plant Journal, 71(6), 990-1001. doi:10.1111/j.1365-313x.2012.05046.xKapoor, M., Tsuda, S., Tanaka, Y., Mayama, T., Okuyama, Y., Tsuchimoto, S., & Takatsuji, H. (2002). Role of petuniapMADS3in determination of floral organ and meristem identity, as revealed by its loss of function. The Plant Journal, 32(1), 115-127. doi:10.1046/j.1365-313x.2002.01402.xPan, I. L., McQuinn, R., Giovannoni, J. J., & Irish, V. F. (2010). Functional diversification of AGAMOUS lineage genes in regulating tomato flower and fruit development. Journal of Experimental Botany, 61(6), 1795-1806. doi:10.1093/jxb/erq046Pnueli, L., Hareven, D., Rounsley, S. D., Yanofsky, M. F., & Lifschitz, E. (1994). Isolation of the tomato AGAMOUS gene TAG1 and analysis of its homeotic role in transgenic plants. The Plant Cell, 6(2), 163-173. doi:10.1105/tpc.6.2.163Dreni, L., & Kater, M. M. (2013). MADSreloaded: evolution of theAGAMOUSsubfamily genes. New Phytologist, 201(3), 717-732. doi:10.1111/nph.12555Brunner, A. M. (2000). Plant Molecular Biology, 44(5), 619-634. doi:10.1023/a:1026550205851Perl-Treves, R., Kahana, A., Rosenman, N., Xiang, Y., & Silberstein, L. (1998). Expression of Multiple AGAMOUS-Like Genes in Male and Female Flowers of Cucumber (Cucumis sativus L.). Plant and Cell Physiology, 39(7), 701-710. doi:10.1093/oxfordjournals.pcp.a029424Yu, D., Kotilainen, M., Pöllänen, E., Mehto, M., Elomaa, P., Helariutta, Y., … Teeri, T. H. (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (Asteraceae). The Plant Journal, 17(1), 51-62. doi:10.1046/j.1365-313x.1999.00351.xDong, Z., Zhao, Z., Liu, C., Luo, J., Yang, J., Huang, W., … Luo, D. (2005). Floral Patterning in Lotus japonicus. Plant Physiology, 137(4), 1272-1282. doi:10.1104/pp.104.054288Hofer, J. M., & Noel Ellis, T. (2014). Developmental specialisations in the legume family. Current Opinion in Plant Biology, 17, 153-158. doi:10.1016/j.pbi.2013.11.014Fourquin, C., del Cerro, C., Victoria, F. C., Vialette-Guiraud, A., de Oliveira, A. C., & Ferrándiz, C. (2013). A Change in SHATTERPROOF Protein Lies at the Origin of a Fruit Morphological Novelty and a New Strategy for Seed Dispersal in Medicago Genus. Plant Physiology, 162(2), 907-917. doi:10.1104/pp.113.217570Hewitt EJ (1966) Sand and Water Culture Methods Used in the Study of Plant Nutrition. Farnham Royal, UK: Commonwealth Agricultural Bureau.Cheng, X., Wang, M., Lee, H.-K., Tadege, M., Ratet, P., Udvardi, M., … Wen, J. (2013). An efficient reverse genetics platform in the model legumeMedicago truncatula. New Phytologist, 201(3), 1065-1076. doi:10.1111/nph.12575D’ Erfurth, I., Cosson, V., Eschstruth, A., Lucas, H., Kondorosi, A., & Ratet, P. (2003). Efficient transposition of theTnt1tobacco retrotransposon in the model legumeMedicago truncatula. The Plant Journal, 34(1), 95-106. doi:10.1046/j.1365-313x.2003.01701.xTadege, M., Ratet, P., & Mysore, K. S. (2005). Insertional mutagenesis: a Swiss Army knife for functional genomics of Medicago truncatula. Trends in Plant Science, 10(5), 229-235. doi:10.1016/j.tplants.2005.03.009Tadege, M., Wen, J., He, J., Tu, H., Kwak, Y., Eschstruth, A., … Mysore, K. S. (2008). Large-scale insertional mutagenesis using the Tnt1 retrotransposon in the model legume Medicago truncatula. The Plant Journal, 54(2), 335-347. doi:10.1111/j.1365-313x.2008.03418.xCheng, X., Wen, J., Tadege, M., Ratet, P., & Mysore, K. S. (2010). Reverse Genetics in Medicago truncatula Using Tnt1 Insertion Mutants. Plant Reverse Genetics, 179-190. doi:10.1007/978-1-60761-682-5_13Benlloch, R., d’ Erfurth, I., Ferrandiz, C., Cosson, V., Beltrán, J. P., Cañas, L. A., … Ratet, P. (2006). Isolation of mtpim Proves Tnt1 a Useful Reverse Genetics Tool in Medicago truncatula and Uncovers New Aspects of AP1-Like Functions in Legumes. Plant Physiology, 142(3), 972-983. doi:10.1104/pp.106.083543Larkin, M. A., Blackshields, G., Brown, N. P., Chenna, R., McGettigan, P. A., McWilliam, H., … Higgins, D. G. (2007). Clustal W and Clustal X version 2.0. Bioinformatics, 23(21), 2947-2948. doi:10.1093/bioinformatics/btm404Altschul, S. (1997). Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Research, 25(17), 3389-3402. doi:10.1093/nar/25.17.3389Tamura, K., Dudley, J., Nei, M., & Kumar, S. (2007). MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) Software Version 4.0. Molecular Biology and Evolution, 24(8), 1596-1599. doi:10.1093/molbev/msm092Dellaporta, S. L., Wood, J., & Hicks, J. B. (1983). A plant DNA minipreparation: Version II. Plant Molecular Biology Reporter, 1(4), 19-21. doi:10.1007/bf02712670Schmittgen, T. D., & Livak, K. J. (2008). Analyzing real-time PCR data by the comparative CT method. Nature Protocols, 3(6), 1101-1108. doi:10.1038/nprot.2008.73Constantin, G. D., Krath, B. N., MacFarlane, S. A., Nicolaisen, M., Elisabeth Johansen, I., & Lund, O. S. (2004). Virus-induced gene silencing as a tool for functional genomics in a legume species. The Plant Journal, 40(4), 622-631. doi:10.1111/j.1365-313x.2004.02233.xWesley, S. V., Helliwell, C. A., Smith, N. A., Wang, M., Rouse, D. T., Liu, Q., … Waterhouse, P. M. (2001). Construct design for efficient, effective and high-throughput gene silencing in plants. The Plant Journal, 27(6), 581-590. doi:10.1046/j.1365-313x.2001.01105.xGuerineau F, Mullineaux P (1993) Plant transformation and expression vectors. In: Croy R, editor. Plant Molecular Biology. Oxford, UK: Bios Scientific Publishers, Academic Press. pp. 121–147.Clough, S. J., & Bent, A. F. (1998). Floral dip: a simplified method forAgrobacterium-mediated transformation ofArabidopsis thaliana. The Plant Journal, 16(6), 735-743. doi:10.1046/j.1365-313x.1998.00343.xBenlloch, R., Roque, E., Ferrándiz, C., Cosson, V., Caballero, T., Penmetsa, R. V., … Madueño, F. (2009). Analysis of B function in legumes: PISTILLATA proteins do not require the PI motif for floral organ development inMedicago truncatula. The Plant Journal, 60(1), 102-111. doi:10.1111/j.1365-313x.2009.03939.xRoque, E., Serwatowska, J., Cruz Rochina, M., Wen, J., Mysore, K. S., Yenush, L., … Cañas, L. A. (2012). Functional specialization of duplicated AP3-like genes inMedicago truncatula. The Plant Journal, 73(4), 663-675. doi:10.1111/tpj.12068Flanagan, C. A., Hu, Y., & Ma, H. (1996). Specific expression of the AGL1 MADS-box gene suggests regulatory functions in Arabidopsis gynoecium and ovule development. The Plant Journal, 10(2), 343-353. doi:10.1046/j.1365-313x.1996.10020343.xSieburth, L. E., & Meyerowitz, E. M. (1997). Molecular dissection of the AGAMOUS control region shows that cis elements for spatial regulation are located intragenically. The Plant Cell, 9(3), 355-365. doi:10.1105/tpc.9.3.355Busch, M. A. (1999). Activation of a Floral Homeotic Gene in Arabidopsis. Science, 285(5427), 585-587. doi:10.1126/science.285.5427.585Moyroud, E., Minguet, E. G., Ott, F., Yant, L., Posé, D., Monniaux, M., … Parcy, F. (2011). Prediction of Regulatory Interactions from Genome Sequences Using a Biophysical Model for the Arabidopsis LEAFY Transcription Factor. The Plant Cell, 23(4), 1293-1306. doi:10.1105/tpc.111.083329Grønlund, M., Constantin, G., Piednoir, E., Kovacev, J., Johansen, I. E., & Lund, O. S. (2008). Virus-induced gene silencing in Medicago truncatula and Lathyrus odorata. Virus Research, 135(2), 345-349. doi:10.1016/j.virusres.2008.04.005Mandel, M. A., Bowman, J. L., Kempin, S. A., Ma, H., Meyerowitz, E. M., & Yanofsky, M. F. (1992). Manipulation of flower structure in transgenic tobacco. Cell, 71(1), 133-143. doi:10.1016/0092-8674(92)90272-eMizukami, Y., & Ma, H. (1992). Ectopic expression of the floral homeotic gene AGAMOUS in transgenic Arabidopsis plants alters floral organ identity. Cell, 71(1), 119-131. doi:10.1016/0092-8674(92)90271-dCannon, S. B., Sterck, L., Rombauts, S., Sato, S., Cheung, F., Gouzy, J., … Young, N. D. (2006). Legume genome evolution viewed through the Medicago truncatula and Lotus japonicus genomes. Proceedings of the National Academy of Sciences, 103(40), 14959-14964. doi:10.1073/pnas.0603228103Young, N. D., & Bharti, A. K. (2012). Genome-Enabled Insights into Legume Biology. Annual Review of Plant Biology, 63(1), 283-305. doi:10.1146/annurev-arplant-042110-103754Jager, M. (2003). MADS-Box Genes in Ginkgo biloba and the Evolution of the AGAMOUS Family. Molecular Biology and Evolution, 20(5), 842-854. doi:10.1093/molbev/msg089Johansen, B., Pedersen, L. B., Skipper, M., & Frederiksen, S. (2002). MADS-box gene evolution—structure and transcription patterns. Molecular Phylogenetics and Evolution, 23(3), 458-480. doi:10.1016/s1055-7903(02)00032-5Rutledge, R., Regan, S., Nicolas, O., Fobert, P., Côté, C., Bosnich, W., … Stewart, D. (1998). Characterization of an AGAMOUS homologue from the conifer black spruce ( Picea mariana ) that produces floral homeotic conversions when expressed in Arabidopsis. The Plant Journal, 15(5), 625-634. doi:10.1046/j.1365-313x.1998.00250.xParcy, F., Nilsson, O., Busch, M. A., Lee, I., & Weigel, D. (1998). A genetic framework for floral patterning. Nature, 395(6702), 561-566. doi:10.1038/26903Causier, B., Bradley, D., Cook, H., & Davies, B. (2009). Conserved intragenic elements were critical for the evolution of the floral C-function. The Plant Journal, 58(1), 41-52. doi:10.1111/j.1365-313x.2008.03759.xAiroldi, C. A., & Davies, B. (2012). Gene Duplication and the Evolution of Plant MADS-box Transcription Factors. Journal of Genetics and Genomics, 39(4), 157-165. doi:10.1016/j.jgg.2012.02.008Giménez, E., Pineda, B., Capel, J., Antón, M. T., Atarés, A., Pérez-Martín, F., … Lozano, R. (2010). Functional Analysis of the Arlequin Mutant Corroborates the Essential Role of the ARLEQUIN/TAGL1 Gene during Reproductive Development of Tomato. PLoS ONE, 5(12), e14427. doi:10.1371/journal.pone.0014427Kater, M. M., Colombo, L., Franken, J., Busscher, M., Masiero, S., Van Lookeren Campagne, M. M., & Angenent, G. C. (1998). Multiple AGAMOUS Homologs from Cucumber and Petunia Differ in Their Ability to Induce Reproductive Organ Fate. The Plant Cell, 10(2), 171-182. doi:10.1105/tpc.10.2.171Tsuchimoto, S., van der Krol, A. R., & Chua, N. H. (1993). Ectopic expression of pMADS3 in transgenic petunia phenocopies the petunia blind mutant. The Plant Cell, 5(8), 843-853. doi:10.1105/tpc.5.8.843Airoldi, C. A., Bergonzi, S., & Davies, B. (2010). Single amino acid change alters the ability to specify male or female organ identity. Proceedings of the National Academy of Sciences, 107(44), 18898-18902. doi:10.1073/pnas.1009050107Causier, B., Castillo, R., Zhou, J., Ingram, R., Xue, Y., Schwarz-Sommer, Z., & Davies, B. (2005). Evolution in Action: Following Function in Duplicated Floral Homeotic Genes. Current Biology, 15(16), 1508-1512. doi:10.1016/j.cub.2005.07.063Birchler, J. A., & Veitia, R. A. (2007). The Gene Balance Hypothesis: From Classical Genetics to Modern Genomics. The Plant Cell, 19(2), 395-402. doi:10.1105/tpc.106.049338Birchler, J. A., & Veitia, R. A. (2009). The gene balance hypothesis: implications for gene regulation, quantitative traits and evolution. New Phytologist, 186(1), 54-62. doi:10.1111/j.1469-8137.2009.03087.xEdger, P. P., & Pires, J. C. (2009). Gene and genome duplications: the impact of dosage-sensitivity on the fate of nuclear genes. Chromosome Research, 17(5), 699-717. doi:10.1007/s10577-009-9055-9Freeling, M. (2006). Gene-balanced duplications, like tetraploidy, provide predictable drive to increase morphological complexity. Genome Research, 16(7), 805-814. doi:10.1101/gr.368140

Direct constraint on the Higgs–charm coupling from a search for Higgs boson decays into charm quarks with the ATLAS detector

A search for the Higgs boson decaying into a pair of charm quarks is presented. The analysis uses proton–proton collisions to target the production of a Higgs boson in association with a leptonically decaying W or Z boson. The dataset delivered by the LHC at a centre-of-mass energy of and recorded by the ATLAS detector corresponds to an integrated luminosity of 139 fb−1. Flavour-tagging algorithms are used to identify jets originating from the hadronisation of charm quarks. The analysis method is validated with the simultaneous measurement of WW, WZ and ZZ production, with observed (expected) significances of 2.6 (2.2) standard deviations above the background-only prediction for the (W/Z)Z(→cc¯) process and 3.8 (4.6) standard deviations for the (W/Z)W(→cq) process. The (W/Z)H(→cc¯) search yields an observed (expected) upper limit of 26 (31) times the predicted Standard Model cross-section times branching fraction for a Higgs boson with a mass of , corresponding to an observed (expected) constraint on the charm Yukawa coupling modifier |κc|<8.5 (12.4), at the 95% confidence level. A combination with the ATLAS (W/Z)H,H→bb¯ analysis is performed, allowing the ratio κc/κb to be constrained to less than 4.5 at the 95% confidence level, smaller than the ratio of the b- and c-quark masses, and therefore determines the Higgs-charm coupling to be weaker than the Higgs-bottom coupling at the 95% confidence level

Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 TeV with the ATLAS detector

This paper presents the measurement of the electroweak production of two jets in association with a $Z\gamma$ pair with the $Z$ boson decaying into two neutrinos. It also presents the search for invisible or partially invisible decays of a Higgs boson with a mass of 125 GeV produced through vector-boson fusion with a photon in the final state. These results use data from LHC proton-proton collisions at $\sqrt{s}$ = 13 TeV collected with the ATLAS detector corresponding to an integrated luminosity of 139 fb$^{-1}$. The event signature, shared by all benchmark processes considered for measurements and searches, is characterized by a significant amount of unbalanced transverse momentum and a photon in the final state, in addition to a pair of forward jets. For electroweak production of $Z\gamma$ in association with two jets, the background-only hypothesis is rejected with an observed (expected) significance of 5.2 (5.1) standard deviations. The measured fiducial cross-section for this process is 1.31$\pm$0.29 fb. Observed (expected) upper limit of 0.37 (0.34) at 95% confidence level is set on the branching ratio of a 125 GeV Higgs boson to invisible particles, assuming the Standard Model production cross-section. The signature is also interpreted in the context of decays of a Higgs boson to a photon and a dark photon. An observed (expected) 95% CL upper limit on the branching ratio for this decay is set at 0.018 (0.017), assuming the 125 GeV Standard Model Higgs boson production cross-section

Nuorten päihteiden käyttö ja vanhempien saama tuki

Nuorten päihteiden käyttö on lisääntynyt viime vuosina. Nuoret eivät yleensä ole päihteistä riippuvaisia, mutta satunnainenkin kokeilu ja käyttö ovat haitallisia. Päihteiden käyttö voi olla yksittäinen ongelma, mutta myös osa suurempaa ongelmakokonaisuutta. Tämän vuoksi nuoren tilannetta tulee tarkastella kokonaisvaltaisesti. Päihteiden käyttöä ei aina huomata, ja sen ilmeneminen voi olla sokki läheisille. Päihteiden käyttö on ongelma käyttäjälle, mutta voi sairastuttaa myös läheiset. Läheiset, usein nuorten vanhemmat, tarvitsevat myös tukea ja neuvoa tilanteessa. Vanhempien oma asenne ja päihdekäyttäytyminen sekä nuoren asioista perillä oleminen ovat tärkeitä ehkäiseviä tekijöitä nuoren päihteiden käytölle. Myös nuoren oma asenne päihteisiin sekä sosiaaliset suhteet ja onnistumisen kokemukset ovat päihteiltä suojaavia tekijöitä. Tämä opinnäytetyö on tehty kokoamalla kattavasti teoriatietoa päihteistä, niiden käytöstä ja haitoista. Etelä-Karjalan sosiaali- ja terveyspiirin (Eksoten) internet-sivuilta selvitettiin, mistä ja miten voi hakea apua ja neuvoja läheisen päihteiden käytön ongelmiin. Lisäksi tehtiin kysely päihdenuorten vanhemmille. Kyselyllä selvitettiin päihdenuorten vanhempien omaa kokemusta saamastaan tuesta sosiaali- ja terveysalan ammattilaisilta. Tulokset analysoitiin empiirisesti. Tulosten mukaan osa vanhemmista on tyyty-väisiä saamaansa tukeen, osa taas kokee, ettei ole saanut tarpeeksi tukea ja tietoa. Päihdepalvelujen parempi ja määrällisesti laajempi saatavuus on kyse-lyyn vastanneiden vanhempien toiveissa. Tästä voidaan päätellä, että päih-denuorten vanhemmat otetaan huomioon ja tukea on tarjolla, mutta kaikkia tuki ei tavoita. Jatkotutkimuksessa voisi selvittää millaiseksi päihdenuoret kokevat saamansa hoidon. Lisäksi voisi selvittää miten sosiaali- ja terveysalan ammattilaiset koke-vat voivansa vaikuttaa nuorten päihdekäyttäytymiseen ja miten sosiaali- ja ter-veysalan ammattilaiset voisivat ottaa päihdenuorten vanhemmat paremmin huomioon. Kirjallisen nuorten päihdeasioita käsittelevän oppaan tekeminen ja jakaminen vanhemmille voisi olla hyödyllinen.Intoxicant use and abuse in young people has increased in recent years. Young people are generally not dependent on intoxicants, but occasional experimentation and use are harmful. Intoxicant use can be a single problem or part of a larger set of problems. Because of this, the situation of the young people should be considered from a broad perspective. Intoxicant use is not always noticed and its appearance may be a shock to those close to the user. Intoxicant use is a problem in the user, but can cause problems for families and friends, as well. Closely related, commonly parents, also need support and counsel in these situations. Parent's own attitudes and customs to use intoxicants, and knowing well issues about young people are important preventive factors for young people's intoxicant use. Also young people's attitude to intoxicant use and social affairs and experience of success are protective factors for intoxicant use. This thesis has been done by collecting comprehensive information on theory of intoxicant consumption and drawbacks of them. With the help of South Karelia District of Social and Health Service's websites, information about where and how to get help and advice for those close to young people with problems was found. In addition to this has been done an inquiry to parents of young people who use intoxicants. By the inquiry, the parents own experiences of having support from professionals in social and health care were examined. The results were analyzed empirically. According to the results, a proportion of parents are satisfied for support they have got, whereas part of parents find that they have not had enough support and information. The parents hope for better and wider availability of services for intoxicant users. Parents of young intoxicant abusers were taken into ac-count, and support services are available, but they do not reach all who need them. For further study, the opinions of the young people, and also of the health professionals about care of intoxicant abusers would be of interest

NEW EMBO MEMBERS’ REVIEW: DNA replication and cell cycle in plants: learning from geminiviruses

Plant cell growth and development depend on continuous cell proliferation which is restricted to small regions of the plant called meristems. Infection by geminiviruses, small DNA viruses whose replicative cycle relies on host cell factors, is excluded from those proliferating areas. Since most of the replicative factors are present, almost exclusively, in proliferating cells, geminivirus infection is believed to induce a cellular state permissive for viral DNA replication, e.g. S-phase or, at least, some specific S-phase functions. The molecular basis for this effect seems to be the interference that certain geminivirus proteins exert on the retinoblastoma-related (RBR) pathway, which analogously to that of animal cells, regulates plant cell cycle activation and G(1)–S transition. In some cases, geminiviruses induce cell proliferation and abnormal growth. Mechanisms other than sequestering plant RBR probably contribute to the multiple effects of geminivirus proteins on cellular gene expression, cell growth control and cellular DNA replication. Current efforts to understand the coupling of geminivirus DNA replication to cell cycle and growth control as well as the directions in which future research is aiming are reviewed