http://goedoc.uni-goettingen.de:80/goescholar Das digitale Repositorium erfasst, speichert, erhält, erschließt und verbreitet digitale Forschungsergebnisse. Wed, 16 May 2012 13:01:45 GMT 2012-05-16T13:01:45Z http://resolver.sub.uni-goettingen.de/purl?gs-goescholar/2720 Points of bounded height on equivariant compactifications of vector groups, I Chambert-Loir, Antoine; Tschinkel, Yuri Fri, 31 Dec 1999 23:00:00 GMT http://resolver.sub.uni-goettingen.de/purl?gs-goescholar/2720 1999-12-31T23:00:00Z http://resolver.sub.uni-goettingen.de/purl?gs-goescholar/2206 Observations on Astraeospongium meniscum (Roemer, 1948) from the Silurian of western Tennessee ; constructional morphology and palaeobiology of the Astraeospongiidae (Calcarea, Heteractinellidae) Mehl, Dorte; Reitner, Joachim Sun, 31 Dec 1995 23:00:00 GMT http://resolver.sub.uni-goettingen.de/purl?gs-goescholar/2206 1995-12-31T23:00:00Z http://resolver.sub.uni-goettingen.de/purl?gs-1/7607 Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans Zhou, Qi; Zhu, Hong-mei; Huang, Quan-fei; Xuan, Zhao-lin; Zhang, Guo-jie; Zhao, Li; Ding, Yun; Roy, Scott; Vicoso, Beatriz; Ruan, Jue; Zhang, Yue; Zhao, Ruo-ping; Mu, Bo; Min, Jiu-meng; Zhang, Qing-hui; Li, Jian-wen; Luo, Yin-ling; Liang, Zu-heng; Ye, Chen; Li, Rui-qiang; Zhang, Xiu-qing; Wang, Jun; Wang, Wen; Bachtrog, Doris Abstract Background Drosophila albomicans is a unique model organism for studying both sex chromosome and B chromosome evolution. A pair of its autosomes comprising roughly 40% of the whole genome has fused to the ancient X and Y chromosomes only about 0.12 million years ago, thereby creating the youngest and most gene-rich neo-sex system reported to date. This species also possesses recently derived B chromosomes that show non-Mendelian inheritance and significantly influence fertility. Methods We sequenced male flies with B chromosomes at 124.5-fold genome coverage using next-generation sequencing. To characterize neo-Y specific changes and B chromosome sequences, we also sequenced inbred female flies derived from the same strain but without B's at 28.5-fold. Results We assembled a female genome and placed 53% of the sequence and 85% of the annotated proteins into specific chromosomes, by comparison with the 12 Drosophila genomes. Despite its very recent origin, the non-recombining neo-Y chromosome shows various signs of degeneration, including a significant enrichment of non-functional genes compared to the neo-X, and an excess of tandem duplications relative to other chromosomes. We also characterized a B-chromosome linked scaffold that contains an actively transcribed unit and shows sequence similarity to the subcentromeric regions of both the ancient X and the neo-X chromosome. Conclusions Our results provide novel insights into the very early stages of sex chromosome evolution and B chromosome origination, and suggest an unprecedented connection between the births of these two systems in D. albomicans. Sat, 31 Dec 2011 23:00:00 GMT http://resolver.sub.uni-goettingen.de/purl?gs-1/7607 2011-12-31T23:00:00Z http://resolver.sub.uni-goettingen.de/purl?gs-1/7606 Epstein-Barr virus LMP2A signalling in statu nascendi mimics a B cell antigen receptor-like activation signal Engels, Niklas; Yigit, Gokhan; Emmerich, Christoph H; Czesnik, Dirk; Schild, Detlev; Wienands, Jurgen Abstract Background The latent membrane protein (LMP) 2A of Epstein-Barr virus (EBV) is expressed during different latency stages of EBV-infected B cells in which it triggers activation of cytoplasmic protein tyrosine kinases. Early studies revealed that an immunoreceptor tyrosine-based activation motif (ITAM) in the cytoplasmic N-terminus of LMP2A can trigger a transient increase of the cytosolic Ca2+ concentration similar to that observed in antigen-activated B cells when expressed as a chimeric transmembrane receptor. Even so, LMP2A was subsequently ascribed an inhibitory rather than an activating function because its expression seemed to partially inhibit B cell antigen receptor (BCR) signaling in EBV-transformed B cell lines. However, the analysis of LMP2A signaling has been hampered by the lack of cellular model systems in which LMP2A can be studied without the influence of other EBV-encoded factors. Results We have reanalyzed LMP2A signaling using B cells in which LMP2A is expressed in an inducible manner in the absence of any other EBV signaling protein. This allowed us for the first time to monitor LMP2A signaling in statu nascendi as it occurs during the EBV life cycle in vivo. We show that mere expression of LMP2A not only stimulated protein tyrosine kinases but also induced phospholipase C-γ2-mediated Ca2+ oscillations followed by activation of the extracellular signal-regulated kinase (Erk) mitogen-activated protein kinase pathway and induction of the lytic EBV gene bzlf1. Furthermore, expression of the constitutively phosphorylated LMP2A ITAM modulated rather than inhibited BCR-induced Ca2+ mobilization. Conclusion Our data establish that LMP2A expression has a function beyond the putative inhibition of the BCR by generating a ligand-independent cellular activation signal that may provide a molecular switch for different EBV life cycle stages and most probably contributes to EBV-associated lymphoproliferative disorders. Sat, 31 Dec 2011 23:00:00 GMT http://resolver.sub.uni-goettingen.de/purl?gs-1/7606 2011-12-31T23:00:00Z http://resolver.sub.uni-goettingen.de/purl?gs-1/7605 Die Bekämpfung des Hungers und der Streit um die Weltagrarmärkte in der Doha-Runde der WTO: Imperialistische Politik und ihre Kritiker Frieling, Hans-Dieter von Die World Trade Organization (WTO) und besonders die Doha- Verhandlungen über die Weltagrarmärkte stehen vielfach in der Kritik, gegenüber der dringlichen Aufgabe zu versagen, den Hunger in der Welt zu bekämpfen. Zum einen wird eine Ausweitung des Freihandels gefordert und mit der ökonomischen Theorie von Ricardo begründet. Zum anderen werden ein gerechter, fairer Welthandel und ein Recht auf Ernährungssouveränität gefordert. Beide Standpunkte werden hier kritisiert. Sie unterstellen ein Politikversagen, das nicht erklären kann, warum Staaten Freihandel und Protektionismus betreiben. Zur Begründung der Kritik wird auf allgemeiner Ebene der Zusammenhang zwischen der Dynamik von Akkumulation und räumlicher Expansion in kapitalistischen Ökonomien und dem Interesse moderner Staaten am Außenhandel erörtert. Es wird dargelegt, in welcher Weise die Institution WTO ein Mittel imperialistischer Politik ist. Als konkrete Beispiele hierfür werden die Doha-Runde und der gegenwärtige Streit um den Agrarhandel untersucht. Sie zeigen die konkreten Ziele und Verlaufsformen imperialistischer Politik sowie die Rolle der WTO und der Weltmarktentwicklung in der Konkurrenz der Staaten um den abstrakten Reichtum, in der das (Über-)Leben der Hungernden nur als unattraktive Geschäftssphäre vorkommt. Mon, 31 Dec 2007 23:00:00 GMT http://resolver.sub.uni-goettingen.de/purl?gs-1/7605 2007-12-31T23:00:00Z