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Heidelberg, Germany

Maitre J.-L.,EMBL | Heisenberg C.-P.,IST Austria
Current Biology | Year: 2013

Cadherins are transmembrane proteins that mediate cell-cell adhesion in animals. By regulating contact formation and stability, cadherins play a crucial role in tissue morphogenesis and homeostasis. Here, we review the three major functions of cadherins in cell-cell contact formation and stability. Two of those functions lead to a decrease in interfacial tension at the forming cell-cell contact, thereby promoting contact expansion - first, by providing adhesion tension that lowers interfacial tension at the cell-cell contact, and second, by signaling to the actomyosin cytoskeleton in order to reduce cortex tension and thus interfacial tension at the contact. The third function of cadherins in cell-cell contact formation is to stabilize the contact by resisting mechanical forces that pull on the contact. © 2013 Elsevier Ltd. Source

The present invention relates to unnatural amino acids comprising a cyclooctynyl or trans-cyclooctenyl analog group and having formula (I) or an acid or base addition salt thereof. The invention also relates to the use of said unnatural amino acids, kits and processes for preparation of polypeptides that comprise one or more than one cyclooctynyl or trans-cyclooctenyl analog group. These polypeptides can be covalently modified by in vitro or in vivo reaction with compounds comprising an azide, nitrile oxide, nitrone, diazocarbonyl or 1,2,4,5-tetrazine group.

The basics of sexual reproduction appear to be very simple: sperm plus egg cell equals embryo. But within cells, it gets trickier: simply combining the genetic content of two cells would lead to disaster; every generation would carry twice as much DNA as its parents. To prevent this, egg and sperm cells halve their genetic content before fusing. A similar issue arises with structures called centrioles. Centrioles act as anchors for the spindle apparatus, which pulls genetic material apart during cell division. If a fertilised egg has centrioles from both the egg cell and the sperm, its genetic material will be pulled in too many directions and it will be shared unevenly between the resulting cells, which is likely to make the embryo unviable. So in animals, before an egg cell is fertilised by a sperm, its centrioles are eliminated, ensuring that the resulting embryo receives only the sperm's centrioles. When a cell is dividing, each anchor point is actually a pair of centrioles: a mature 'mother' centriole, and an immature 'daughter' centriole. "Mother centrioles are known to be very, very stable," says Péter Lénárt from EMBL, who led the work. "In the worm C.elegans, people have tagged a mother centriole in the sperm, and found it still intact in the late embryo!" To investigate how the egg cell manages to rid itself of such a resilient structure, Joana Pinto, a PhD student in the Lénárt lab, developed fluorescent tags for mother and daughter centrioles in a starfish egg cell and recorded the entire process of eliminating them. She found that the egg cell expels the two mother centrioles, jettisoning them into the two 'polar bodies' that also serve as dumps for its surplus genetic material. One daughter centriole is also dragged into a polar body, leaving the other daughter centriole alone in the egg cell. "This only happens in egg cell formation," says Lénárt. "In a normal division a single daughter centriole is never left alone." "It seems that if this daughter is alone it is unstable, and will be degraded," says Pinto. "But if we make a mother centriole stay in the cell, it doesn't get destroyed, so the fertilised egg ends up with a tripolar spindle and can't divide." Thanks to further probing aided by an electron microscopy technique developed at EMBL by Yannick Schwab's lab, the scientists found that mother centrioles are expelled into polar bodies thanks to little appendages that centrioles acquire as they mature. Their data suggests that these appendages direct mother centrioles to the cell membrane, ready for ejection. The scientists would like to probe further into how mother centrioles are transported and ejected, and investigate how and why isolated daughter centrioles break down. "Eggs are incredibly diverse - think of chickens, frogs, starfish - so I doubt that this is exactly the same in all animals," says Lénárt. "But underlying that diversity are conserved modules like the centrioles. By understanding the molecular logic of how those modules can be combined in different ways, we can begin to reconstruct how this diversity evolved." More information: Borrego-Pinto et al. Journal of Cell Biology, 21 March 2016. DOI: 10.1083/201510083

Letunic I.,EMBL | Bork P.,EMBL
Nucleic Acids Research | Year: 2011

Interactive Tree Of Life (http://itol.embl.de) is a web-based tool for the display, manipulation and annotation of phylogenetic trees. It is freely available and open to everyone. In addition to classical tree viewer functions, iTOL offers many novel ways of annotating trees with various additional data. Current version introduces numerous new features and greatly expands the number of supported data set types. Trees can be interactively manipulated and edited. A free personal account system is available, providing management and sharing of trees in user defined workspaces and projects. Export to various bitmap and vector graphics formats is supported. Batch access interface is available for programmatic access or inclusion of interactive trees into other web services. © 2011 The Author(s). Source

Letunic I.,Biobyte Solutions GmbH | Doerks T.,EMBL | Bork P.,EMBL
Nucleic Acids Research | Year: 2015

SMART (Simple Modular Architecture Research Tool) is a web resource (http://smart.embl.de/) providing simple identification and extensive annotation of protein domains and the exploration of protein domain architectures. In the current version, SMART contains manually curated models for more than 1200 protein domains, with ∼200 new models since our last update article. The underlying protein databases were synchronized with UniProt, Ensembl and STRING, bringing the total number of annotated domains and other protein features above 100 million. SMART's 'Genomic' mode, which annotates proteins from completely sequenced genomes was greatly expanded and now includes 2031 species, compared to 1133 in the previous release. SMART analysis results pages have been completely redesigned and include links to several new information sources. A new, vector-based display engine has been developed for protein schematics in SMART, which can also be exported as highresolution bitmap images for easy inclusion into other documents. Taxonomic tree displays in SMART have been significantly improved, and can be easily navigated using the integrated search engine. © The Author(s) 2014. Source

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