Bedeutung und Regulation des Methioninzyklus in Pflanzen

Im Methioninzyklus wird Methylthioadenosin (MTA), das Nebenprodukt der Ethylen-, Polyamin- und Nicotianaminbiosynthese, über eine Reihe von Zwischenschritten zu Methionin (Met) recycelt. Die Regulation und Bedeutung dieses Zyklus sind bislang nur wenig verstanden. In dieser Arbeit wurde die Bedeutung des Methioninzyklus für die Ethylensynthese, sowie für die Metabolisierung von MTA über die Analyse von Mutanten in Arabidopsis untersucht.As a by-product of ethylene, polyamine and nicotianamine synthesis, methylthioadenosine (MTA) is released and subsequently recycled to methionine (Met) through the Met cycle. The role of the Met cycle in plant sulfur metabolism as well as its regulation are only poorly understood. In this study Arabidopsis mutants were employed in order to analyze the role of the Met cycle for ethlylene synthesis and for the metabolization of MTA

A chloroplast retrograde signal, 3’phosphoadenosine 5’-phosphate, acts as a secondary messenger in abscisic acid signaling in stomatal closure and germination

Organelle-nuclear retrograde signaling regulates gene expression, but its roles in specialized cells and integration with hormonal signaling remain enigmatic. Here we show that the SAL1-PAP (3'-phosphoadenosine 5'- phosphate) retrograde pathway interacts with abscisic acid (ABA) signaling to regulate stomatal closure and seed germination in Arabidopsis. Genetically or exogenously manipulating PAP bypasses the canonical signaling components ABA Insensitive 1 (ABI1) and Open Stomata 1 (OST1); priming an alternative pathway that restores ABA-responsive gene expression, ROS bursts, ion channel function, stomatal closure and drought tolerance in ost1-2. PAP also inhibits wild type and abi1-1 seed germination by enhancing ABA sensitivity. PAP-XRN signaling interacts with ABA, ROS and Ca2+; up-regulating multiple ABA signaling components, including lowly-expressed Calcium Dependent Protein Kinases (CDPKs) capable of activating the anion channel SLAC1. Thus, PAP exhibits many secondary messenger attributes and exemplifies how retrograde signals can have broader roles in hormone signaling, allowing chloroplasts to fine-tune physiological responses.Wannarat Pornsiriwong, Gonzalo M Estavillo, Kai Xun Chan, Estee E Tee, Diep Ganguly, Peter A Crisp, Su Yin Phua, Chenchen Zhao, Jiaen Qiu, Jiyoung Park, Miing Tiem Yong, Nazia Nisar, Arun Kumar Yadav, Benjamin Schwessinger, John Rathjen, Christopher I Cazzonelli, Philippa B Wilson, Matthew Gilliham, Zhong-Hua Chen, Barry J Pogso

Microtubule-associated protein IQ67 DOMAIN5 regulates morphogenesis of leaf pavement cells in Arabidopsis thaliana.

Plant microtubules form a highly dynamic intracellular network with important roles for regulating cell division, cell proliferation, and cell morphology. Their organization and dynamics are co-ordinated by various microtubule-associated proteins (MAPs) that integrate environmental and developmental stimuli to fine-tune and adjust cytoskeletal arrays. IQ67 DOMAIN (IQD) proteins recently emerged as a class of plant-specific MAPs with largely unknown functions. Here, using a reverse genetics approach, we characterize Arabidopsis IQD5 in terms of its expression domains, subcellular localization, and biological functions. We show that IQD5 is expressed mostly in vegetative tissues, where it localizes to cortical microtubule arrays. Our phenotypic analysis of iqd5 loss-of-function lines reveals functions of IQD5 in pavement cell (PC) shape morphogenesis. Histochemical analysis of cell wall composition further suggests reduced rates of cellulose deposition in anticlinal cell walls, which correlate with reduced anisotropic expansion. Lastly, we demonstrate IQD5-dependent recruitment of calmodulin calcium sensors to cortical microtubule arrays and provide first evidence for important roles for calcium in regulation of PC morphogenesis. Our work identifies IQD5 as a novel player in PC shape regulation and, for the first time, links calcium signaling to developmental processes that regulate anisotropic growth in PCs

A novel plant actin-microtubule bridging complex regulates cytoskeletal and ER structure at ER-PM contact sites

In plants, the cortical endoplasmic reticulum (ER) network is connected to the plasma membrane (PM) through the ER-PM contact sites (EPCSs), whose structures are maintained by EPCS resident proteins and the cytoskeleton.1, 2, 3, 4, 5, 6, 7 Strong co-alignment between EPCSs and the cytoskeleton is observed in plants,1,8 but little is known of how the cytoskeleton is maintained and regulated at the EPCS. Here, we have used a yeast-two-hybrid screen and subsequent in vivo interaction studies in plants by fluorescence resonance energy transfer (FRET)-fluorescence lifetime imaging microscopy (FLIM) analysis to identify two microtubule binding proteins, KLCR1 (kinesin-light-chain-related protein 1) and IQD2 (IQ67-domain 2), that interact with the actin binding protein NET3C and form a component of plant EPCS that mediates the link between the actin and microtubule networks. The NET3C-KLCR1-IQD2 module, acting as an actin-microtubule bridging complex, has a direct influence on ER morphology and EPCS structure. Their loss-of-function mutants, net3a/NET3C RNAi, klcr1, or iqd2, exhibit defects in pavement cell morphology, which we suggest is linked to the disorganization of both actin filaments and microtubules. In conclusion, our results reveal a novel cytoskeletal-associated complex, which is essential for the maintenance and organization of cytoskeletal structure and ER morphology at the EPCS and for normal plant cell morphogenesis

SAM levels, gene expression of SAM synthetase, methionine synthase and ACC oxidase, and ethylene emission from N. suaveolens flowers

S′adenosyl-l-methionine (SAM) is a ubiquitous methyl donor and a precursor in the biosynthesis of ethylene, polyamines, biotin, and nicotianamine in plants. Only limited information is available regarding its synthesis (SAM cycle) and its concentrations in plant tissues. The SAM concentrations in flowers of Nicotiana suaveolens were determined during day/night cycles and found to fluctuate rhythmically between 10 and 50 nmol g−1 fresh weight. Troughs of SAM levels were measured in the evening and night, which corresponds to the time when the major floral scent compound, methyl benzoate, is synthesized by a SAM dependent methyltransferase (NsBSMT) and when this enzyme possesses its highest activity. The SAM synthetase (NsSAMS1) and methionine synthase (NsMS1) are enzymes, among others, which are involved in the synthesis and regeneration of SAM. Respective genes were isolated from a N. suaveolens petal cDNA library. Transcript accumulation patterns of both SAM regenerating enzymes matched perfectly those of the bifunctional NsBSMT; maximum mRNA accumulations of NsMS1 and NsSAMS1 were attained in the evening. Ethylene, which is synthesized from SAM, reached only low levels of 1–2 ppbv in N. suaveolens flowers. It is emitted in a burst at the end of the life span of the flowers, which correlates with the increased expression of the 1-aminocyclopropane-1-carboxylate oxidase (NsACO)

Glucocorticoid deficiency causes transcriptional and post-transcriptional reprogramming of glutamine metabolism

Background Deficient glucocorticoid biosynthesis leading to adrenal insufficiency is life-threatening and is associated with significant co-morbidities. The affected pathways underlying the pathophysiology of co-morbidities due to glucocorticoid deficiency remain poorly understood and require further investigation. Methods To explore the pathophysiological processes related to glucocorticoid deficiency, we have performed global transcriptional, post-transcriptional and metabolic profiling of a cortisol-deficient zebrafish mutant with a disrupted ferredoxin (fdx1b) system. Findings fdx1b−/− mutants show pervasive reprogramming of metabolism, in particular of glutamine-dependent pathways such as glutathione metabolism, and exhibit changes of oxidative stress markers. The glucocorticoid-dependent post-transcriptional regulation of key enzymes involved in de novo purine synthesis was also affected in this mutant. Moreover, fdx1b−/− mutants exhibit crucial features of primary adrenal insufficiency, and mirror metabolic changes detected in primary adrenal insufficiency patients. Interpretation Our study provides a detailed map of metabolic changes induced by glucocorticoid deficiency as a consequence of a disrupted ferredoxin system in an animal model of adrenal insufficiency. This improved pathophysiological understanding of global glucocorticoid deficiency informs on more targeted translational studies in humans suffering from conditions associated with glucocorticoid deficiency. Fund Marie Curie Intra-European Fellowships for Career Development, HGF-programme BIFTM, Deutsche Forschungsgemeinschaft, BBSRC

Patronage and Selfishness towards Jews. Disputes and Conflicts about Jews along the Eastern Border of the Roman-German Empire during the 13th and 14th Centuries.

Judenschutz und Eigennutz. Auseinandersetzungen um die Juden an der Ostgrenze des Römisch-Deutschen Reiches im 13. und 14. Jahrhundert Jürgen Bürstenbinder Die Publikation beschreibt und analysiert Aspekte jüdischen Lebens in den Gebieten von Mecklenburg, Pommern, Brandenburg, Böhmen, Mähren, Schlesien und Polen im 13. und 14. Jahrhundert. Hauptsächlich werden zeitgenössische Quellen wie Staatsschriften, Schutzbriefe, Verträge, Stadtbücher, Steuerlisten, Beschriftungen von Grabsteinen und andere Mitteilungen verwendet. Bei Einzelaspekten wird auch Sekundärliteratur herangezogen. Besonderer Wert wurde auf die Analyse der Parallelen und der Unterschiede jüdischer Lebensumstände zum christlichen Umfeld gelegt. In den beiden Jahrhunderten waren Juden für alle Herrschenden eine wichtige Einnahmequelle und wurden daher häufig wie andere Regalien oder Vermögensgegenstände behandelt. In den Auseinandersetzungen zwischen Kaisern, Landesherren, Städten und der römischen Kirche hatten Juden keinen Kombattantenstatus, sie waren lediglich Objekte der Auseinandersetzungen. Entsprechend wurde über die Menschen und deren Eigen-tum verfügt. Beispiele aus der Untersuchungsregion zeigen die weitgefächerten Zugriffsmöglichkeiten. Papst Gregor IX. bestimmte 1234 namens der römischen Kirche die „perpetua servitus“ für Juden, konnte aber keine durchsetzbare Rechtsnorm schaffen. Bis zum Jahr 1236 galten Juden nach mittelalterlichem Recht als Freie. Erst Kaiser Friedrich II. änderte mit der Erneuerung eines Privilegs den Rechtsstatus der Juden als „servi came-rae“. Es wird gezeigt, dass dieser Begriff in Anlehnung an Aristoteles‘ Definition von Sklaven und an die Begriffe der Finanzverwaltung aus dem Königreich Sizilien entstand. Eine als Privileg angesehene Feststellung des Kaisers machte Freie zu seinem sächlichen Eigentum. Ab dem Jahr 1244 wurden landesherrliche Judenstatuten erlassen. Herzog Friedrich II. von Österreich, der im Kampf gegen den Kaiser stand, definierte eine Rechtsnorm, die Juden in das christliche Rechtssystem integrierte und einen Rechtsschutz bot. Dieses bahnbrechende Statut wurde bis in das 15. Jahrhundert in mehreren Herrschaftsbereichen an der Ostgrenze des Reiches erneuert. Daher schlägt der Autor vor, die gesamte Familie von Statuten als „Codex Iuris Fridericianum“ zu bezeichnen. An einem generellen Kommunikationsmodell werden die Möglichkeiten zur Weiterverbreitung dieser Statuten untersucht. Im Gegensatz zu der Entwicklung auf Landesebene forderte die römische Kirche auf dem 4. Laterankonzil und auf Provinzialsynoden in Breslau und Wien eine weitgehende Ausgrenzung der Juden, was ihr nur teilweise gelang. Mehrere der dortigen Detailforderungen wurden in späteren Jahrhunderten von Antisemiten erneut aufgenommen und durchgesetzt. In der Zeit zwischen 1348 und 1350 geißelte die große Pest Europa. Etwa 30 % der Bevölkerung starben an der Seuche. Der Anteil der jüdischen Toten war deutlich höher, aber nicht nur wegen der Pest. Die christliche Bevölkerung war durch eine pseudo-religiöse Konditionierung darauf eingestellt, Juden als Feinde des Christentums zu sehen und als „Gottesmörder“ zu vernichten. In der Arbeit wird die Ausbreitung von Judenhass und Pogromen mit den medizinischen Begriffen der Epidemie, Pandemie und Endemie verglichen. Beim Zusammentreffen von extremen Belastungen durch Kälteeinbrüche, Missernten, Hungers-nöte und schließlich der großen Pest kam es zur ersten europaweiten pandemischen Ju-denvernichtung, die in ihrem schrecklichen Umfang erst wieder von den Nationalsozialisten und ihren Helfern übertroffen wurde. Das jüdische Finanzwesen wird an einigen ausgewählten Kreditverträgen untersucht und in Vergleich zur christlichen Geschäftspraxis gestellt. Es wird gezeigt, dass viele Aspekte dieser jüdischen Verträge noch heute gängige Praxis von Banken sind. Die Siedlung von Juden wird für das Gebiet an der Ostgrenze untersucht, gegenüber der Standardliteratur vervollständigt, auf Plausibilität überprüft und in einen Zusammenhang mit der deutschen Ostsiedlung gestellt. In vielen Fällen folgte die Besiedlung dem gleichen Muster und verlief sehr ähnlich. Das Resultat der Auseinandersetzungen um die Juden im 13. und 14. Jahrhundert bestand darin, dass sie aus fast ganz Europa vertrieben wurden, nach Osten wanderten, beim Aufbau Polens halfen, und dort trotz aller weiteren Verfolgungen ihr Hauptsiedlungsgebiet bis 1939 fanden. Viele Handlungen, die wie Judenschutz aussahen, dienten zugleich oder überwiegend dem Eigennutz der Herrschenden.Patronage and Selfishness towards Jews. Disputes and Conflicts about Jews along the Eastern Border of the Roman-German Empire during the 13th and 14th Centuries Juergen Buerstenbinder This publication describes and analyses aspects of Jewish life in the regions of Mecklen-burg, Pomerania, Brandenburg, Bohemia, Moravia, Silesia and Poland, all located along the Eastern border of the Roman-German empire, during the 13th and 14th centuries. This work is based mainly on contemporary sources as official state papers, custodial letters and contractual papers, books from city administrations, tax lists, and inscriptions from gravestones and other types of messages. For some specific aspects only secondary literature has been referenced. Special emphasis has been given to the analysis of similar and different circumstances of Jewish life in comparison to Christian environments. During both centuries, Jews formed a significant source of income for all ruling parties. Therefore, the Jewish people have been treated as other legal ownership or treasuries. Jews did not achieve a status of full combatants during the conflicts between emperors, regional rulers, cities and the Roman Church. Jews were simply objects in the conflicts. Following this concept Jews and their possessions were in free disposition. Examples from the region investigated illustrate the wide spread of possibilities accessing the people and their properties. In 1234 pope Gregory IX decreed in the name of the Roman Church the so called “perpetua servitus” for Jews. But, he could not convert this attempt into a legal norm. Following medieval law Jews were free people up to the year 1236. Emperor Frederic II modified this status while renewing a “privilege”. He generated the legal status for Jews as “servi camerae”. It has been shown that this concept is based on Aristotle’s definition of slaves and on the understanding of the financial administration in the kingdom of Sicily. Finally, an imperial letter, originally meant as a privilege, transformed free people into financial properties. From the year 1244 on, regional statutes concerning Jews have been granted. Duke Frederic II of Austria, who was in a military conflict with the emperor, was the first to define a legal normative integrating Jews into the Christian legal system and simultaneously offer-ing protection to this group. This epoch-making statute has been renewed up to the 15th century in many regions along the eastern border of the empire. Therefore the author proposes a specific term for the complete family of statues: “Codex Iuris Fridericianum”. Potential paths for transfer of statutes are investigated on the basis of a general communication model. In contrary to the regional developments the Roman Church demanded on the 4th Lateran Council and at regional synods in Breslau and in Vienna a strict separation of Jews from the Christian society, which succeeded only in parts. Several of the de-tailed regulations have been adopted and applied by Anti-Semites in later centuries. From 1348 up to 1350 the great plague tortured people in Europe. More than 30 percent of the population died on the epidemic. The respective percentage of the Jewish population was significantly higher, not only because of the plague. The Christian population was conditioned by pseudo-religious argumentation to understand Jews as murderers of God and extinguish the Jews. This work discusses and compares the spread of hatred and pogroms against Jews in relation to epidemic, pandemic and endemic processes in medicine. With extreme pressure from severe coldness, crop failure, famine and finally the great plague all together the first Europe wide pandemic persecution of Jews happened. Only Nazi and their supporters raged more severely. The Jewish financial system of the period has been investigated based on several credit contracts. Furthermore, it has been related to the respective Christian business procedures. It has been shown that several details and procedures from the old Jewish contracts are still in use in our days with respect to the financial system. The settlement of Jews on the eastern border has been investigated; the description has been completed in comparison to standard literature, checked for plausibility and connected to the German settlements in the East. Frequently both migrations appeared in parallel and following the same pattern. As a result of all disputes and conflicts about Jews in the 13th and 14th centuries it can be seen that Jews have been expelled from nearly all Europe, migrated to the East, helped to build up Poland, suffered from ongoing pogroms and nonetheless kept their main settle-ments in Poland until 1939. Many actions appealing as patronage or protection of Jews were – looking at the details – mainly selfishness and greed from the ruling parties

Achtjähriges Verweilen eines Schrotkornes in der vorderen Augenkammer: Casuistiche Mittheilung

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