- Seminars - maillist.psb.ugent.be

PSB event reminder
by contact＠psb.vib-ugent.be 23 Jun '11

23 Jun '11

Calendar Name: seminars Scheduled for: Thursday, June 23 2011, 11:00 - 12:30 Event text: Dr Hannele Tuominen Ume� Plant Science Centre Department of Plant Physiology Ume� University Ume� SWEDEN Details: �Identification of novel regulators of lignification and programmed cell death of xylem elements� ABSTRACT Xylem maturation involves lignification and programmed cell death (PCD) that are interlinked through the action of the NAC family transcription factors. The downstream regulators and the executioners are poorly known. We have identified two metacaspase genes as candidates for such key regulators in Populus trees on the basis of specific upregulation during the xylem cell death phase of wood formation. The closest Arabidopsis homologue to these two Populus genes is METACASPASE9 (AtMC9, At5g04200). Also AtMC9 shows xylem specific expression pattern throughout the plant, suggesting involvement in xylem cell death. In order to characterise the function of AtMC9 in xylem development, a reverse genetic approach was taken in Arabidopsis. AtMC9 T-DNA knock-out lines showed rather normal progression of protoxylem differentiation and PCD in in vitro grown seedling roots by analysis of genetic crosses to various xylem reporter lines. Interestingly, AtMC9 RNAi lines revealed increased overall growth of the plants, which together with double mutant analyses in the metacaspase family suggest involvement of AtMC9 together with other type II metacaspase genes in growth control. We are currently performing proteomic analyses to identify targets of the AtMC9 action. Upstream regulators have been sought by screening an EMS mutagenised proAtMC9::GFP reporter line. We have also utilized the Zinnia elegans in vitro tracheary element (TE) differentiation system to identify novel regulators of lignification and PCD. In this system, application of silver thiosulphate (STS) blocked both lignification and PCD of TEs resulting in prolonged lifespan of the TEs, while TE secondary cellulose formation was not affected. This allowed us to identify novel genes specifically involved in lignification and/or PCD by analyzing differential gene expression patterns between cell cultures treated with or without STS. One of the identified genes was a PIRIN gene that was previously implicated in transcriptional regulation in mammals. Expression of the Zinnia PIRIN gene was strongly upregulated during lignification and/or PCD of normally developing TEs, whereas no upregulation was present in non-lignifying TEs after STS treatment. Functional analysis of the PIRIN gene family was undertaken in Arabidopsis thaliana which contains four PIRIN (PRN) homologs: AtPRN1 (At3g59220), AtPRN2 (At2g43120), AtPRN3 (At3g59260) and AtPRN4 (At1g50590). Promoter activity assay by using GUS reporter gene showed that, out of the four PIRIN genes, AtPRN2 was most specifically expressed in the vascular tissues. Pyrolysis-GC/MS analysis of the various PIRIN gene family mutants suggests involvement of AtPRN2 in control of lignification. However, in vitro and in vivo analyses demonstrated interaction of AtPRN2 with several different types of proteases, which suggests involvement of AtPRN2 primarily in regulation of hydrolytic processes during xylem cell death. We can therefore link together the two processes of lignification and PCD and provide evidence on a novel player in this interplay.

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PSB event reminder
by contact＠psb.vib-ugent.be 21 Jun '11

21 Jun '11

Calendar Name: seminars Scheduled for: Thursday, June 23 2011, 11:00 - 12:30 Event text: Dr Hannele Tuominen Ume� Plant Science Centre Department of Plant Physiology Ume� University Ume� SWEDEN Details: �Identification of novel regulators of lignification and programmed cell death of xylem elements� ABSTRACT Xylem maturation involves lignification and programmed cell death (PCD) that are interlinked through the action of the NAC family transcription factors. The downstream regulators and the executioners are poorly known. We have identified two metacaspase genes as candidates for such key regulators in Populus trees on the basis of specific upregulation during the xylem cell death phase of wood formation. The closest Arabidopsis homologue to these two Populus genes is METACASPASE9 (AtMC9, At5g04200). Also AtMC9 shows xylem specific expression pattern throughout the plant, suggesting involvement in xylem cell death. In order to characterise the function of AtMC9 in xylem development, a reverse genetic approach was taken in Arabidopsis. AtMC9 T-DNA knock-out lines showed rather normal progression of protoxylem differentiation and PCD in in vitro grown seedling roots by analysis of genetic crosses to various xylem reporter lines. Interestingly, AtMC9 RNAi lines revealed increased overall growth of the plants, which together with double mutant analyses in the metacaspase family suggest involvement of AtMC9 together with other type II metacaspase genes in growth control. We are currently performing proteomic analyses to identify targets of the AtMC9 action. Upstream regulators have been sought by screening an EMS mutagenised proAtMC9::GFP reporter line. We have also utilized the Zinnia elegans in vitro tracheary element (TE) differentiation system to identify novel regulators of lignification and PCD. In this system, application of silver thiosulphate (STS) blocked both lignification and PCD of TEs resulting in prolonged lifespan of the TEs, while TE secondary cellulose formation was not affected. This allowed us to identify novel genes specifically involved in lignification and/or PCD by analyzing differential gene expression patterns between cell cultures treated with or without STS. One of the identified genes was a PIRIN gene that was previously implicated in transcriptional regulation in mammals. Expression of the Zinnia PIRIN gene was strongly upregulated during lignification and/or PCD of normally developing TEs, whereas no upregulation was present in non-lignifying TEs after STS treatment. Functional analysis of the PIRIN gene family was undertaken in Arabidopsis thaliana which contains four PIRIN (PRN) homologs: AtPRN1 (At3g59220), AtPRN2 (At2g43120), AtPRN3 (At3g59260) and AtPRN4 (At1g50590). Promoter activity assay by using GUS reporter gene showed that, out of the four PIRIN genes, AtPRN2 was most specifically expressed in the vascular tissues. Pyrolysis-GC/MS analysis of the various PIRIN gene family mutants suggests involvement of AtPRN2 in control of lignification. However, in vitro and in vivo analyses demonstrated interaction of AtPRN2 with several different types of proteases, which suggests involvement of AtPRN2 primarily in regulation of hydrolytic processes during xylem cell death. We can therefore link together the two processes of lignification and PCD and provide evidence on a novel player in this interplay.

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PSB event reminder
by contact＠psb.vib-ugent.be 07 Jun '11

07 Jun '11

Calendar Name: seminars Scheduled for: Tuesday, June 7 2011, 11:00 - 12:30 Event text: Prof Fran�ois Chaumont Institut des Sciences de la Vie Universit� catholique de Louvain Louvain-la-Neuve Belgium Details: �Plasma membrane aquaporins: a highly regulated plumbing system� ABSTRACT Aquaporins are channels facilitating the movement of water and/or uncharged solutes across membranes in all kingdoms of life. Plant aquaporins constitute a large and highly divergent protein family, and members of several subfamilies are found in the plasma membrane. Recently, we characterized proteins from a new subfamily (XIP or X Intrinsic proteins) found in Solanaceae but absent from Arabidopsis and monocots and showed that they facilitate the transport of many uncharged substrates. Besides this new aquaporin subfamily, the most studied plant plasma membrane aquaporins are the PIPs (Plasma membrane Intrinsic Proteins) that control cellular water movement in many different physiological processes. Using molecular and biophysical approaches, we showed that the expression and activity of the PIPs are regulated in Zea mays roots and leaves according to the developmental stages, day/night cycle and in response to short-term osmotic stress. Beyond the initial regulatory step of controlling gene and protein expression, different mechanisms have been reported to regulate the traffic and gating of PIPs. Maize aquaporins belonging to PIP1 and PIP2 groups formed hetero-oligomers to regulate the traffic of ZmPIP1 from the endoplasmic reticulum to the plasma membrane. In addition, a conserved cysteine residue located in an extra-cytosolic loop is involved in a disulfide bridge formation between two monomers forming a dimer. The delivery of ZmPIP2s to the plasma membrane involves also interaction with the syntaxin SYP121. Altogether the data point toward a complex and highly integrated regulation of PIP trafficking and activity in the maintenance of cellular water homeostasis.

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PSB event reminder
by contact＠psb.vib-ugent.be 05 Jun '11

05 Jun '11

Calendar Name: seminars Scheduled for: Tuesday, June 7 2011, 11:00 - 12:30 Event text: Prof Fran�ois Chaumont Institut des Sciences de la Vie Universit� catholique de Louvain Louvain-la-Neuve Belgium Details: �Plasma membrane aquaporins: a highly regulated plumbing system� ABSTRACT Aquaporins are channels facilitating the movement of water and/or uncharged solutes across membranes in all kingdoms of life. Plant aquaporins constitute a large and highly divergent protein family, and members of several subfamilies are found in the plasma membrane. Recently, we characterized proteins from a new subfamily (XIP or X Intrinsic proteins) found in Solanaceae but absent from Arabidopsis and monocots and showed that they facilitate the transport of many uncharged substrates. Besides this new aquaporin subfamily, the most studied plant plasma membrane aquaporins are the PIPs (Plasma membrane Intrinsic Proteins) that control cellular water movement in many different physiological processes. Using molecular and biophysical approaches, we showed that the expression and activity of the PIPs are regulated in Zea mays roots and leaves according to the developmental stages, day/night cycle and in response to short-term osmotic stress. Beyond the initial regulatory step of controlling gene and protein expression, different mechanisms have been reported to regulate the traffic and gating of PIPs. Maize aquaporins belonging to PIP1 and PIP2 groups formed hetero-oligomers to regulate the traffic of ZmPIP1 from the endoplasmic reticulum to the plasma membrane. In addition, a conserved cysteine residue located in an extra-cytosolic loop is involved in a disulfide bridge formation between two monomers forming a dimer. The delivery of ZmPIP2s to the plasma membrane involves also interaction with the syntaxin SYP121. Altogether the data point toward a complex and highly integrated regulation of PIP trafficking and activity in the maintenance of cellular water homeostasis.

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Seminar Prof Uli Schurr 28/06
by Delphine Verspeel 01 Jun '11

01 Jun '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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Seminar Dr Hannele Tuominen 23/06
by Delphine Verspeel 01 Jun '11

01 Jun '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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PSB event reminder
by contact＠psb.vib-ugent.be 01 Jun '11

01 Jun '11

Calendar Name: seminars Scheduled for: Wednesday, June 1 2011, 11:00 - 12:30 Event text: Dr Jos� M Jim�nez-G�mez Max Planck Institute for Plant Breeding Research Plant Breeding and Genetics Department K�ln GERMANY Details: �RNA-seq analysis in tomato and its wild relatives� ABSTRACT Wild tomato species are native to diverse habitats in South America and show wide morphological and ecological diversity that has proven useful in breeding programs. The current high throughput sequencing technologies have the ability to characterize genome-wide genetic variation in sequences, expression profiles and other molecular events with an effect in adaptation and development. We have used RNA-seq and smallRNA-seq to sequence cultivated tomato (Solanum lycopersicum) and three wild relatives: S. pennellii, S. habrochaites and S. pimpinellifolium, generating up to 50x -150x coverage of their transcriptome. Since only a draft of the genome sequence of cultivated tomato is currently available, it was required to combine well-established methodologies with custom protocols to effectively obtain relevant information from the short reads generated from the wild species. Our approaches have allowed us to infer genome-wide polymorphisms, species-specific expression differences and small RNA landscapes in tomato. I will present the rationale behind the bioinformatic protocols used for our analysis and the results obtained. In addition, we are now integrating the functional and evolutionary information obtained to identify candidate genes underlying phenotypic variation between tomato and its wild relatives.

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Seminar Prof François Chaumont 07/06
by Delphine Verspeel 30 May '11

30 May '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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PSB event reminder
by contact＠psb.vib-ugent.be 30 May '11

30 May '11

Calendar Name: seminars Scheduled for: Wednesday, June 1 2011, 11:00 - 12:30 Event text: Dr Jos� M Jim�nez-G�mez Max Planck Institute for Plant Breeding Research Plant Breeding and Genetics Department K�ln GERMANY Details: �RNA-seq analysis in tomato and its wild relatives� ABSTRACT Wild tomato species are native to diverse habitats in South America and show wide morphological and ecological diversity that has proven useful in breeding programs. The current high throughput sequencing technologies have the ability to characterize genome-wide genetic variation in sequences, expression profiles and other molecular events with an effect in adaptation and development. We have used RNA-seq and smallRNA-seq to sequence cultivated tomato (Solanum lycopersicum) and three wild relatives: S. pennellii, S. habrochaites and S. pimpinellifolium, generating up to 50x -150x coverage of their transcriptome. Since only a draft of the genome sequence of cultivated tomato is currently available, it was required to combine well-established methodologies with custom protocols to effectively obtain relevant information from the short reads generated from the wild species. Our approaches have allowed us to infer genome-wide polymorphisms, species-specific expression differences and small RNA landscapes in tomato. I will present the rationale behind the bioinformatic protocols used for our analysis and the results obtained. In addition, we are now integrating the functional and evolutionary information obtained to identify candidate genes underlying phenotypic variation between tomato and its wild relatives.

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Seminar Dr José M Jiménez-Gómez 01/06
by Delphine Verspeel 25 May '11

25 May '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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