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Arabidopsis synaptotagmin 1 (SYT1) is localized on the endoplasmic reticulum–plasma membrane (ER–PM) contact sites in leaf and root cells. The ER–PM localization of Arabidopsis SYT1 resembles that of the extended synaptotagmins (E-SYTs) in animal cells. In mammals, E-SYTs have been shown to regulate calcium signaling, lipid transfer, and endocytosis. Arabidopsis SYT1 was reported to be essential for maintaining cell integrity and virus movement. This study provides detailed insight into the subcellular localization of SYT1 and VAP27-1, another ER–PM-tethering protein. SYT1 and VAP27-1 were shown to be localized on distinct ER–PM contact sites. The VAP27-1-enriched ER–PM contact sites (V-EPCSs) were always in contact with the SYT1-enriched ER–PM contact sites (S-EPCSs). The V-EPCSs still existed in the leaf epidermal cells of the SYT1 null mutant; however, they were less stable than those in the wild type. The polygonal networks of cortical ER disassembled and the mobility of VAP27-1 protein on the ER–PM contact sites increased in leaf cells of the SYT1 null mutant. These results suggest that SYT1 is responsible for stabilizing the ER network and V-EPCSs.

The plant-parasitic nematode Heterodera schachtii is an obligate biotroph that induces syncytial feeding sites in roots of its hosts. Nematodes produce effectors that are secreted into the host and facilitate infection process. Here we identified H. schachtii protein disulphide isomerase (HsPDI) as a putative effector that interferes with the host’s redox status. In situ hybridization showed that HsPdi is specifically localized within esophageal glands of pre-parasitic second stage juveniles (J2). HsPdi is up-regulated in the early parasitic J2s. Silencing of HsPdi by RNA interference in the J2s hampers their development and leads to structural malfunctions in associated feeding sites induced in Arabidopsis roots. Expression of HsPDI in Arabidopsis increases plant’s susceptibility towards H. schachtii . HsPdi expression is up-regulated in the presence of exogenous H 2 O 2 , whereas HsPdi silencing results in increased mortality under H 2 O 2 stress. Stable expression of HsPDI in Arabidopsis plants decreases ROS burst induced by flg22. Transiently expressed HsPDI in N. benthamiana leaves is localized in the apoplast. HsPDI plays an important role in the interaction between nematode and plant, probably through inducing local changes in the redox status of infected host tissue. It also contributes to protect the nematode from exogenous H 2 O 2 stress.

Plant-targeted pCB302 plasmids containing sequences encoding gfp fusions with a microtubule-binding domain; gfp with the fimbrin actin-binding domain 2; and gfp with AtRACK1C from Arabidopsis thaliana, all harbored in Agrobacterium tumefaciens, were used to assay heterologous expression on three different clades of the photosynthetic dinoflagellate, Symbiodinium. Accessibility to the resistant cell wall and through the plasma membrane of these dinoflagellates was gained after brief but vigorous shaking in the presence of glass beads and polyethylene glycol. A resistance gene to the herbicide Basta allowed appropriate selection of the cells expressing the hybrid proteins, which showed a characteristic green fluorescence, although they appeared to lose their photosynthetic pigments and did not further divide. Cell GFP expression frequency measured as green fluorescence emission yielded 839 per every 106 cells for Symbiodinium kawagutii, followed by 640 and 460 per every 106 cells for Symbiodinium microadriaticum and Symbiodinium sp. Mf11, respectively. Genomic PCR with specific primers amplified the AtRACK1C and gfp sequences after selection in all clades, thus revealing their presence in the cells. RT-PCR from RNA of S. kawagutii co-incubated with A. tumefaciens harboring each of the three vectors with their respective constructs, amplified products corresponding to the heterologous gfp sequence while no products were obtained from three distinct negative controls. The reported procedure shows that mild abrasion followed by co-incubation with A. tumefaciens harboring heterologous plasmids with CaMV35S and nos promoters can lead to expression of the encoded proteins into the Symbiodinium cells in culture. Despite the obvious drawbacks of the procedure, this is an important first step towards a stable transformation of Symbiodinium.

Choral singing in Germany during the Weimar Republic was enormously popular. The reasons for the expansion of choral singing were the social and political upheavals that could be symbolically compensated in the collective singing. One of the greatest choir association was the social-democratic Deutsche Arbeiter-Sängerbund (DAS), which showed a positive future-oriented approach to the new social situation. The efforts of the DAS to adapt to the changed political and social conditions are clearly demonstrated by the two choir collections published in 1926 and 1929 by the DAS management. The two collections were intended to create the vocal prerequisites for the repertoire that was appropriate for the working class. At no time choral singing was as popular in Germany as during the Weimar Republic. The reasons for the expansion of choral singing were the social, economic and political upheavals and uncertainties that could be compensated, at least symbolically, in the collective singing. Moreover, war veterans were able to keep their community in male choirs and remember their fallen comrades by singing. The two largest choir associations were the bourgeois »Deutscher Sängerbund« (DSB) and the social democratically oriented »Deutscher Arbeiter-Sängerbund« (DAS). In contrast to the DSB, the DAS showed a positive future-oriented approach to the new social situation after the collapse of the Monarchy and the founding of the Republic. The working class now fully participated in the political shaping of the situation. If the political attitude of the workers’ singers in the Empire was characterised by a fundamental opposition, this was no longer an appropriate position for the DAS after 1918. An exception were the decidedly communist-oriented workers’ singers. However, the conflicts between the two camps within the workers’ singers only broke out openly towards the end of the Weimar Republic. The efforts of the DAS to adapt to the changed political and social conditions are clearly demonstrated by the two choir collections published by the DAS management. The DAS published an extensive collection for mixed unaccompanied choirs in 1926, followed three years later by male unaccompanied choirs. The two collections were intended to achieve several things: a) they were to replace the old workers’ songs (»Tendenzlieder«) of the pre-war period; b) they were to make the broadest possible spectrum of music history and art music accessible to workers’ singers; c) the political class standpoint was to be implemented vocally in a manner appropriate to the times. The structure and repertoire of the two collections show not only unmistakable continuities but also demarcations from the vocal culture of the former empire. An essential aspect was the artistic aspiration that was expressed in the collections. Many workers’ choirs wanted to tap into the repertoire of art music and thus conquer bourgeois vocal terrain. At the same time there were reservations about bourgeois individualism. Instead of Romanticism, they therefore tended to fall back on the music of the 16th and 17th centuries, which was considered less subjective and more committed to an ideal of community. The real aim of the choral collections, however, was to create the vocal prerequisites for the performance of a demanding repertoire that was appropriate for the working class, but did not yet exist. With the world economic crisis, the opposition to bourgeois choral societies intensified in the DAS. Conflicts also increased within the working class singers, and the orientation towards art music increasingly faced competition from an orientation towards rhythmic chants and contemporary battle songs. Ni u kojem drugom razdoblju nije zborsko pjevanje bilo tako popularno u Njemačkoj kao u doba Weimarske republike. Razlozi za širenje zborskog pjevanja bili su društveni, gospodarski i politički preokreti i nesigurnosti koje se moglo barem simbolički kompenzirati kolektivnim pjevanjem. Uz to, ratni veterani mogli su svoje zajedništvo održavati u muškim zborovima i pjevanjem se prisjećati svojih palih drugova. Dvije najveće zborske udruge bile su građanski »Deutscher Sängerbund« (DSB) i socijaldemokratski orijentirani »Deutscher Arbeiter-Sängerbund« (DAS). Za razliku od DSB-a, DAS je očitovao na budućnost orijentiran pozitivni pristup novim društvenim prilikama nakon raspada Monarhije i utemeljenja Republike. Radnička klasa je sada u potpunosti mogla sudjelovati u političkom oblikovanju prilika. Ako je politički stav radnika pjevača u Carstvu bio karakteriziran kao temeljna opozicija, nakon 1918. to za DAS više nije bio prihvatljiv stav. Iznimku su predstavljali odlučno komunistički orijentirani radnici pjevači. Međutim, sukobi između dvaju tabora unutar radnika pjevača izbili su u javnost tek pri kraju Weimarske republike. Napori DAS-a da se prilagodi izmijenjenim političkim i društvenim prilikama jasno se vide u dvjema zborskim zbirkama koje je objavila uprava DAS-a. Godine 1926. DAS je objavio opsežnu zbirku mješovitih zborova bez pratnje, a tri godine kasnije uslijedilo je objavljivanje zbirke za muške zborove bez pratnje. Svrha je ovih dviju zbirka imala nekoliko ciljeva: 1) trebale su nadomjestiti stare radničke pjesme (»Tendenzlieder«) iz predratnog razdoblja; b) trebale su predstaviti najširi mogući spektar povijesti glazbe i umjetničke glazbe dostupne radnicima pjevačima; c) političko klasno stajalište trebalo je vokalno usaditi na način prikladan vremenu. Struktura i repertoar ovih dviju zbirka pokazuje ne samo nepogrešiv kontinuitet nego i razgraničenja u odnosu na vokalnu kulturu prethodnog Carstva. Bitan aspekt predstavljala je umjetnička težnja izražena u zbirkama. Mnogi radnički zborovi željeli su zadrijeti u repertoar umjetničke glazbe i tako osvojiti teren građanske vokalnosti. Istodobno je postojala suzdržanost u odnosu na građanski individualizam. Umjesto romantizma, oni su stoga težili vratiti se glazbi 16. i 17. stoljeća, koju se smatralo manje subjektivnom i posvećenijom idealu zajedništva. No pravi cilj zborskih zbirka bio je stvaranje vokalnih preduvjeta za izvođenje zahtjevnog repertoara koji bi bio prikladan radničkoj klasi, ali još nije postojao. S porastom svjetske gospodarske krize u DAS-u se intenziviralo protivljenje građanskim zborskim društvima. Povećali su se i sukobi unutar pjevača iz radničke klase, a orijentacija prema umjetničkoj glazbi sve se više na konkurentski način suočavala s ritmičkim pjevom i suvremenim borbenim pjesmama.

Plant tip growth has been recognized as an actin-based cellular process requiring targeted exocytosis and compensatory endocytosis to occur at the growth cone. However, the identity of subcellular compartments involved in polarized membrane trafficking pathways remains enigmatic in plants. Here we characterize endosomal compartments in tip-growing root hair cells. We demonstrate their presence at the growing tip and differential distribution upon cessation of tip growth. We also show that both the presence of endosomes as well as their rapid movements within the tip region depends on an intact actin cytoskeleton and involves actin polymerization. In conclusion, actin-propelled endosomal motility is tightly linked to the polar tip growth of root hairs.

BACKGROUND AND AIMS: Neutral red (NR), a lipophilic phenazine dye, has been widely used in various biological systems as a vital stain for bright-field microscopy. In its unprotonated form it penetrates the plasma membrane and tonoplast of viable plant cells, then due to protonation it becomes trapped in acidic compartments. The possible applications of NR for confocal laser scanning microscopy (CLSM) studies were examined in various aspects of plant root biology. METHODS: NR was used as a fluorochrome for living roots of Phaseolus vulgaris, Allium cepa, A. porrum and Arabidopsis thaliana (wild-type and transgenic GFP-carrying lines). The tissues were visualized using CLSM. The effect of NR on the integrity of the cytoskeleton and the growth rate of arabidopsis primary roots was analysed to judge potential toxic effects of the dye. KEY RESULTS: The main advantages of the use of NR are related to the fact that NR rapidly penetrates root tissues, has affinity to suberin and lignin, and accumulates in the vacuoles. It is shown that NR is a suitable probe for visualization of proto- and metaxylem elements, Casparian bands in the endodermis, and vacuoles in cells of living roots. The actin cytoskeleton and the microtubule system of the cells, as well as the dynamics of root growth, remain unchanged after short-term application of NR, indicating a relatively low toxicity of this chemical. It was also found that NR is a useful probe for the observation of the internal structures of root nodules and of fungal hyphae in vesicular-arbuscular mycorrhizas. CONCLUSIONS: Ease, low cost and absence of tissue processing make NR a useful probe for structural, developmental and vacuole-biogenetic studies of plant roots with CLSM.

Plasma membrane repair in animal cells uses synaptotagmin 7, a Ca²⁺-activated membrane fusion protein that mediates delivery of intracellular membranes to wound sites by a mechanism resembling neuronal Ca²⁺-regulated exocytosis. Here, we show that loss of function of the homologous Arabidopsis thaliana Synaptotagmin 1 protein (SYT1) reduces the viability of cells as a consequence of a decrease in the integrity of the plasma membrane. This reduced integrity is enhanced in the syt1-2 null mutant in conditions of osmotic stress likely caused by a defective plasma membrane repair. Consistent with a role in plasma membrane repair, SYT1 is ubiquitously expressed, is located at the plasma membrane, and shares all domains characteristic of animal synaptotagmins (i.e., an N terminus-transmembrane domain and a cytoplasmic region containing two C2 domains with phospholipid binding activities). Our analyses support that membrane trafficking mediated by SYT1 is important for plasma membrane integrity and plant fitness.

Das Reformationsjubiläum im Jahr 2017 ging mit einer ,kulturellen Wende' in der Forschung einher.Musik, Literatur, Kunst, Alltags- und Frömmigkeitskultur werden mit wachsender Selbstverständlichkeit als reformationsrelevante Gegenstände behandelt.