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</o:shapelayout></xml><![endif]--></head><body lang=SL link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Vabimo vas na 18. predavanje iz sklopa "Kolokviji na IJS" v letu 2018/19, ki bo <strong><span style='color:red'>v ponedeljek, 17. junija 2019, ob 13 uri </span></strong><span style='color:red'>v Veliki predavalnici Instituta »Jožef Stefan«</span> na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu <a href="http://www.ijs.si/ijsw/Koledar_prireditev">http://www.ijs.si/ijsw/Koledar_prireditev</a>, posnetke preteklih predavanj<span style='color:blue'> </span>pa na <a href="http://videolectures.net/kolokviji_ijs">http://videolectures.net/kolokviji_ijs</a>. <o:p></o:p></p><p class=MsoNormal>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br><br><strong><span style='color:red'><o:p></o:p></span></strong></p><p class=MsoNormal style='text-align:justify'><b><span lang=EN-US>prof. dr. Stephan Clemens </span></b><span lang=EN-US><o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><i><span lang=EN-US>Univerza v Bayreuthu, Bayreuth, Nemčija<o:p></o:p></span></i></p><p class=MsoNormal style='text-align:justify'><i><span lang=EN-US><o:p> </o:p></span></i></p><p class=MsoNormal style='text-align:justify'><b><span style='font-size:14.0pt'>Na poti do pridelkov z optimalno sestavo mikrohranil<o:p></o:p></span></b></p><p class=MsoNormal style='text-align:justify'><b><span style='font-size:14.0pt'><o:p> </o:p></span></b></p><p class=MsoNormal style='text-align:justify'>Prehodne kovine, kot sta cink (Zn) in železo (Fe), so bistvene za domala vsak biološki proces. Sedanje ocene npr. kažejo, da je okoli 10% vseh evkariontskih proteinov odvisnih od Zn. Naše razumevanje načinov pridobivanja in razporeditve teh mikrohranil pa ostaja omejeno. Rastline morajo dobiti esencialne mikroelemente iz talne raztopine, v kateri koncentracija relevantnih ionov lahko variira za več redov velikosti. Težave ne predstavlja le pomanjkanje, temveč tudi strupenost. Presežek Zn ali drugih kovinskih ionov, ki močno interagirajo z različnimi komponentami celic, lahko namreč zavre rast in razvoj. Homeostatični sistem, ki vključuje transporterje za kovine, kovinske ligande in regulatorne proteine, v rastlinskih tkivih vzdržuje koncentracijo esencialnih elementov znotraj razmeroma ozkih fizioloških območij. <o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Kot okoljski faktorji za rastline niso relevantni le makro- in mikroelementi, temveč tudi potencialno zelo strupeni elementi brez biološke funkcije, npr. kadmij (Cd) in arzen (As). Prisotnost ne-esencialnih strupenih elementov v okolju je bodisi naravna bodisi posledica antropogenega onesnaževanja.<o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Zdravstveno stanje ljudi je v mnogočem odvisno od ionoma rastlin, tj. od koncentracije esencialnih in ne-esencialnih elementov, predvsem v užitnih tkivih. Hrana rastlinskega izvora je namreč glavni vir mikrohranil in okoli tri milijarde ljudi po svetu ogroža pomanjkanje Zn in Fe. Prav tako je večina Cd in znaten del As, ki pride v naša telesa, posledica uživanja rastlin. Zato moramo bolje razumeti načine za določanje kopičenja kovin v rastlinah, mesta in mehanizme kopičenja, kakor tudi kemijsko okolje elementov, ki v veliki meri vpliva na njihovo biodostopnost. To bo omogočilo razvoj kmetijskih rastlin z večjimi koncentracijami mikrohranil in mnogo manj nalaganja ne-esencialnih strupenih elementov.<o:p></o:p></p><p class=MsoNormal style='text-align:justify'>V našem laboratoriju proučujemo akumulacijo kovin v rastlinah. Pri tem se osredotočamo na sposobnost določenih rastlinskih vrst, da akumulirajo zelo veliko Zn in Cd – celo 1000-krat več kot ostale rastline. Naša modelna rastlina je Arabidopsis halleri, bližnji sorodnik modelne rastline dvokaličnic (A. thaliana), ki raste v starih rudarskih predelih osrednje Evrope. Hkrati poskušamo identificirati komponente tolerance za kovine pri A. thaliana. Ne nazadnje, raziskujemo še modelni rastlini enokaličnici, to sta riž in ječmen.<o:p></o:p></p><p class=MsoNormal style='text-align:justify'><o:p> </o:p></p><p class=MsoNormal style='text-align:justify'><strong><span style='color:red'>Lepo vabljeni!<o:p></o:p></span></strong></p><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt;margin-left:212.4pt;text-indent:35.4pt'><strong><span style='font-weight:normal'>***********</span></strong><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-US style='color:black'>We invite you to the 18th Institute colloquium in the academic year 2018/19. The colloquium will be held </span><b><span lang=EN-US style='color:red'>on Monday, June 17, 2019 at 13 PM</span></b><span lang=EN-US style='color:red'> in <b>the main Institute lecture hall</b></span><span lang=EN-US style='color:black'>, Jamova 39, Ljubljana. To read the abstract click </span><a href="http://www.ijs.si/ijsw/Koledar_prireditev"><span lang=EN-US>http://www.ijs.si/ijsw/Koledar_prireditev</span></a><span lang=EN-US style='color:#1F497D'>. </span><span lang=EN-US style='color:black'>Past colloquia are posted on</span><span lang=EN-US style='color:#1F497D'> </span><a href="http://videolectures.net/kolokviji_ijs"><span lang=EN-US>http://videolectures.net/kolokviji_ijs</span></a><span lang=EN-US style='color:#1F497D'>.<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US>********************************************<b><o:p></o:p></b></span></p><p class=MsoNormal><b><span lang=EN-US>prof. dr. Stephan Clemens<o:p></o:p></span></b></p><p class=MsoNormal><i><span lang=EN-US>University of Bayreuth, Bayreuth, Germany<o:p></o:p></span></i></p><p class=MsoNormal><i><span lang=EN-US><o:p> </o:p></span></i></p><p class=Default><strong><span lang=EN-US style='font-family:"Arial",sans-serif'>Moving towards micronutrient-optimized crops<o:p></o:p></span></strong></p><p class=Default><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal style='text-align:justify'>Transition metals such as zinc and iron are essential for virtually every biological process. For example, current estimates assume that around 10% of all eukaryotic proteins are zinc-dependent. Our understanding of acquisition and distribution pathways for these micronutrients, however, is still limited. Plants have to acquire essential microelements from soil solutions that can vary in concentrations of the respective ions by orders of magnitude. Not only deficiency is a threat but also toxicity. An excess of zinc or other metal ions can inhibit growth due to their tendency to interact strongly with various cellular components. A homeostatic system comprising metal transporters, metal ligands and regulatory proteins maintains the concentrations of essential elements within rather narrow physiological ranges inside plant tissues. <o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Relevant as environmental factors for plants are not only macro- and microelements, but also potentially highly toxic elements without biological function, for example cadmium and arsenic. Nonessential toxic elements are present in the environment either because of natural causes or because of anthropogenic pollution. <o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Human well-being depends in many ways on the ionome of plants, i.e. the concentrations of essential and nonessential elements especially in edible tissues. Plant-derived food is a major source of micronutrients and an estimated three billion people around the world are threatened by zinc or iron deficiency. Furthermore, most of the human cadmium intake and a large fraction of the arsenic intake are due to the consumption of plants. Thus, we need to better understand the pathways determining metal accumulation in plants, the storage sites and mechanisms as well as the chemical environment, which greatly influences bioavailability. This will enable the generation of crops with elevated micronutrient concentrations and much less accumulation of non-essential, toxic elements. <o:p></o:p></p><p class=MsoNormal style='text-align:justify'>We are pursuing different approaches to dissect metal accumulation in plants. One of them focuses on the ability of certain plant species to hyperaccumulate zinc and cadmium up to levels more than 1000-fold higher than in non-hyperaccumulating plants. Our model is Arabidopsis halleri, a close relative of A. thaliana, and growing in old mining areas in Central Europe. A second approach is aiming at identifying components of metal tolerance in A. thaliana. Finally, we are studying the monocot models rice and barley.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Cordially invited!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p></div></body></html>