@article{SanyalMoriyaLanger2015, author = {Sanyal, D. and Moriya, T. J. and Langer, N.}, title = {Envelope inflation in Wolf-Rayet stars and extended supernova shock breakout signals}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88062}, pages = {213 -- 216}, year = {2015}, abstract = {Massive, luminous stars reaching the Eddington limit in their interiors develop very dilute, extended envelopes. This effect is called envelope inflation. If the progenitors of Type Ib/c supernovae, which are believed to be Wolf-Rayet (WR) stars, have inflated envelopes then the shock breakout signals diffuse in them and can extend their rise times significantly. We show that our inflated, hydrogen-free, WR stellar models with a radius of ∼R⊙ can have shock breakout signals longer than ∼ 60 s. The puzzlingly long shock breakout signal observed in the Type Ib SN 2008D can be explained by an inflated progenitor envelope, and more such events might argue in favour of existence of inflated envelopes in general.}, language = {en} } @article{JaegerErbenSpitznerWustmansetal.2015, author = {Jaeger-Erben, Melanie and Spitzner, Meike and Wustmans, Clemens and Zeeb, Matthias}, title = {Nachhaltige Grundsicherung}, series = {Nachhaltige Grundsicherung: Armut {\"u}berwinden - nat{\"u}rliche Lebensgrundlagen erhalten}, journal = {Nachhaltige Grundsicherung: Armut {\"u}berwinden - nat{\"u}rliche Lebensgrundlagen erhalten}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-6222}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81693}, pages = {43 -- 66}, year = {2015}, language = {de} } @article{Bestenlehner2015, author = {Bestenlehner, J. M.}, title = {Stellar parameters from photometric data for fainter and more distant Wolf-Rayet stars}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88390}, pages = {354}, year = {2015}, abstract = {Spectroscopy is the preferred way to study the physical and wind properties of Wolf-Rayet (WR) stars, but with decreasing brightness and increasing distance of the object spectroscopy become very expensive. However, photometry still delivers a high signal to noise ratio. Current and past astronomical surveys and space missions provide large data sets, that can be harvested to discover new WR stars and study them over a wide metallicity range with the help of state of the art stellar atmosphere and evolutionary models.}, language = {en} } @article{Crowther2015, author = {Crowther, P. A.}, title = {Wolf-Rayet content of the Milky Way}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-87562}, pages = {21 -- 26}, year = {2015}, abstract = {An overview of the known Wolf-Rayet (WR) population of the Milky Way is presented, including a brief overview of historical catalogues and recent advances based on infrared photometric and spectroscopic observations resulting in the current census of 642 (vl.13 online catalogue). The observed distribution of WR stars is considered with respect to known star clusters, given that ≤20\% of WR stars in the disk are located in clusters. WN stars outnumber WC stars at all galactocentric radii, while early-type WC stars are strongly biased against the inner Milky Way. Finally, recent estimates of the global WR population in the Milky Way are reassessed, with 1,200±100 estimated, such that the current census may be 50\% complete. A characteristic WR lifetime of 0.25 Myr is inferred for an initial mass threshold of 25 M⊙.}, language = {en} } @article{Weis2015, author = {Weis, K.}, title = {Family ties of WR to LBV nebulae yielding clues for stellar evolution}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-87949}, pages = {167 -- 170}, year = {2015}, abstract = {Luminous Blue Variables (LBVs) are stars is a transitional phase massive stars may enter while evolving from main-sequence to Wolf-Rayet stars. The to LBVs intrinsic photometric variability is based on the modulation of the stellar spectrum. Within a few years the spectrum shifts from OB to AF type and back. During their cool phase LBVs are close to the Humphreys-Davidson (equivalent to Eddington/Omega-Gamma) limit. LBVs have a rather high mass loss rate, with stellar winds that are fast in the hot and slower in the cool phase of an LBV. These alternating wind velocities lead to the formation of LBV nebulae by wind-wind interactions. A nebula can also be formed in a spontaneous giant eruption in which larger amounts of mass are ejected. LBV nebulae are generally small (< 5 pc) mainly gaseous circumstellar nebulae, with a rather large fraction of LBV nebulae being bipolar. After the LBV phase the star will turn into a Wolf-Rayet star, but note that not all WR stars need to have passed the LBV phase. Some follow from the RSG and the most massive directly from the MS phase. In general WRs have a large mass loss and really fast stellar winds. The WR wind may interact with winds of earlier phases (MS, RSG) to form WR nebulae. As for WR with LBV progenitors the scenario might be different, here no older wind is present but an LBV nebula! The nature of WR nebulae are therefore manifold and in particular the connection (or family ties) of WR to LBV nebulae is important to understand the transition between these two phases, the evolution of massive stars, their winds, wind-wind and wind-nebula interactions. Looking at the similarities and differences of LBV and WR nebula, figuring what is a genuine LBV and WR nebula are the basic question addressed in the analysis presented here.}, language = {en} } @article{Steup2015, author = {Steup, Martin}, title = {Raum und Zahl in der Pflanzenphysiologie}, series = {Raum und Zahl}, journal = {Raum und Zahl}, publisher = {Trafo}, address = {Berlin}, isbn = {978-3-86464-082-7}, pages = {77 -- 109}, year = {2015}, language = {de} } @article{SchwarteWegnerHavensteinetal.2015, author = {Schwarte, Sandra and Wegner, Fanny and Havenstein, Katja and Groth, Detlef and Steup, Martin and Tiedemann, Ralph}, title = {Sequence variation, differential expression, and divergent evolution in starch-related genes among accessions of Arabidopsis thaliana}, series = {Plant molecular biology : an international journal of fundamental research and genetic engineering}, volume = {87}, journal = {Plant molecular biology : an international journal of fundamental research and genetic engineering}, number = {4-5}, publisher = {Springer}, address = {Dordrecht}, issn = {0167-4412}, doi = {10.1007/s11103-015-0293-2}, pages = {489 -- 519}, year = {2015}, abstract = {Transitory starch metabolism is a nonlinear and highly regulated process. It originated very early in the evolution of chloroplast-containing cells and is largely based on a mosaic of genes derived from either the eukaryotic host cell or the prokaryotic endosymbiont. Initially located in the cytoplasm, starch metabolism was rewired into plastids in Chloroplastida. Relocation was accompanied by gene duplications that occurred in most starch-related gene families and resulted in subfunctionalization of the respective gene products. Starch-related isozymes were then evolutionary conserved by constraints such as internal starch structure, posttranslational protein import into plastids and interactions with other starch-related proteins. 25 starch-related genes in 26 accessions of Arabidopsis thaliana were sequenced to assess intraspecific diversity, phylogenetic relationships, and modes of selection. Furthermore, sequences derived from additional 80 accessions that are publicly available were analyzed. Diversity varies significantly among the starch-related genes. Starch synthases and phosphorylases exhibit highest nucleotide diversities, while pyrophosphatases and debranching enzymes are most conserved. The gene trees are most compatible with a scenario of extensive recombination, perhaps in a Pleistocene refugium. Most genes are under purifying selection, but disruptive selection was inferred for a few genes/substitutiones. To study transcript levels, leaves were harvested throughout the light period. By quantifying the transcript levels and by analyzing the sequence of the respective accessions, we were able to estimate whether transcript levels are mainly determined by genetic (i.e., accession dependent) or physiological (i.e., time dependent) parameters. We also identified polymorphic sites that putatively affect pattern or the level of transcripts.}, language = {en} } @article{RadingSandmannSteupetal.2015, author = {Rading, M. Michael and Sandmann, Michael and Steup, Martin and Chiarugi, Davide and Valleriani, Angelo}, title = {Weak correlation of starch and volume in synchronized photosynthetic cells}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {91}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {1}, publisher = {American Physical Society}, address = {College Park}, issn = {1539-3755}, doi = {10.1103/PhysRevE.91.012711}, pages = {11}, year = {2015}, abstract = {In cultures of unicellular algae, features of single cells, such as cellular volume and starch content, are thought to be the result of carefully balanced growth and division processes. Single-cell analyses of synchronized photoautotrophic cultures of the unicellular alga Chlamydomonas reinhardtii reveal, however, that the cellular volume and starch content are only weakly correlated. Likewise, other cell parameters, e.g., the chlorophyll content per cell, are only weakly correlated with cell size. We derive the cell size distributions at the beginning of each synchronization cycle considering growth, timing of cell division and daughter cell release, and the uneven division of cell volume. Furthermore, we investigate the link between cell volume growth and starch accumulation. This work presents evidence that, under the experimental conditions of light-dark synchronized cultures, the weak correlation between both cell features is a result of a cumulative process rather than due to asymmetric partition of biomolecules during cell division. This cumulative process necessarily limits cellular similarities within a synchronized cell population.}, language = {en} } @article{CisekTokarzSteupetal.2015, author = {Cisek, Richard and Tokarz, Danielle and Steup, Martin and Tetlow, Ian J. and Emes, Michael J. and Hebelstrup, Kim H. and Blennow, Andreas and Barzda, Virginijus}, title = {Second harmonic generation microscopy investigation of the crystalline ultrastructure of three barley starch lines affected by hydration}, series = {Biomedical optics express}, volume = {6}, journal = {Biomedical optics express}, number = {10}, publisher = {Optical Society of America}, address = {Washington}, issn = {2156-7085}, doi = {10.1364/BOE.6.003694}, pages = {3694 -- 3700}, year = {2015}, abstract = {Second harmonic generation (SHG) microscopy is employed to study changes in crystalline organization due to altered gene expression and hydration in barley starch granules. SHG intensity and susceptibility ratio values (R'(SHG)) are obtained using reduced Stokes-Mueller polarimetric microscopy. The maximum R'(SHG) values occur at moderate moisture indicating the narrowest orientation distribution of nonlinear dipoles from the cylindrical axis of glucan helices. The maximum SHG intensity occurs at the highest moisture and amylopectin content. These results support the hypothesis that SHG is caused by ordered hydrogen and hydroxyl bond networks which increase with hydration of starch granules. (C) 2015 Optical Society of America}, language = {en} } @article{Ette2015, author = {Ette, Ottmar}, title = {Excellence(s), velociferina(s). On the bestiary of deceptive elites of Bologna}, series = {Literatura : teor{\´i}a, historia, cr{\´i}tica ; revista del Departamento de Literatura}, volume = {17}, journal = {Literatura : teor{\´i}a, historia, cr{\´i}tica ; revista del Departamento de Literatura}, number = {2}, publisher = {Departamento de Literatura, Universidad Nacional de Colombia}, address = {Bogota}, issn = {0123-5931}, pages = {237 -- 242}, year = {2015}, language = {es} } @article{WackerPiephoSpijkerman2015, author = {Wacker, Alexander and Piepho, Maike and Spijkerman, Elly}, title = {Photosynthetic and fatty acid acclimation of four phytoplankton species in response to light intensity and phosphorus availability}, series = {European journal of phycology}, volume = {50}, journal = {European journal of phycology}, number = {3}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0967-0262}, doi = {10.1080/09670262.2015.1050068}, pages = {288 -- 300}, year = {2015}, abstract = {Photosynthetic acclimation of phytoplankton to lower irradiation can be met by several strategies such as increasing the affinity for light or increasing antenna size and stacking of the thylakoids. The latter is reflected by a higher proportion of polyunsaturated fatty acids (PUFAs). Additionally, photosynthetic capacity (P-max), respiratory losses, and proton leakage can be reduced under low light. Here we consider the effect of light intensity and phosphorus availability simultaneously on the photosynthetic acclimation and fatty acid composition of four phytoplankters. We studied representatives of the Chlorophyceae, Cryptophyceae and Mediophyceae, all of which are important components of plankton communities in temperate lakes. In our analysis, excluding fatty acid composition, we found different acclimation strategies in the chlorophytes Scenedesmus quadricauda, Chlamydomonas globosa, cryptophyte Cryptomonas ovata and ochrophyte Cyclotella meneghiniana. We observed interactive effects of light and phosphorus conditions on photosynthetic capacity in S. quadricauda and Cry. ovata. Cry. ovata can be characterized as a low light-acclimated species, whereas S. quadricauda and Cyc. meneghiniana can cope best with a combination of high light intensities and low phosphorus supply. Principal component analyses (PCA), including fatty acid composition, showed further species-specific patterns in their regulation of P-max with PUFAs and light. In S. quadricauda and Cyc. meneghiniana, PUFAs negatively affected the relationship between P-max and light. In Chl. globosa, lower light coincided with higher PUFAs and lower P-max, but PCA also indicated that PUFAs had no direct influence on P-max. PUFAs and P-max were unaffected by light in Cry. ovata. We did not observe a general trend in the four species tested and concluded that, in particular, the interactive effects highlight the importance of taking into account more than one environmental factor when assessing photosynthetic acclimation to lower irradiation.}, language = {en} } @article{SperfeldWacker2015, author = {Sperfeld, Erik and Wacker, Alexander}, title = {Maternal diet of Daphnia magna affects offspring growth responses to supplementation with particular polyunsaturated fatty acids}, series = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica}, volume = {755}, journal = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica}, number = {1}, publisher = {Springer}, address = {Dordrecht}, issn = {0018-8158}, doi = {10.1007/s10750-015-2244-y}, pages = {267 -- 282}, year = {2015}, abstract = {Previous studies examining the effects of food quality on zooplankton often controlled for maternal effects of resource provisioning using standardized maternal diets. However, varying nutritional history of mothers may change resource provisioning to their progeny, especially regarding polyunsaturated fatty acids (PUFAs), which may change the interpretation of previously observed fitness responses of offspring. To assess PUFA-mediated maternal provisioning effects on offspring, we raised females of the cladoceran Daphnia magna on diets differing considerably in PUFA composition and raised their offspring on a PUFA-lacking diet supplemented with the omega 3 PUFAs alpha-linolenic acid (ALA) and/or eicosapentaenoic acid (EPA). The mass-specific growth responses of offspring to their own diets were affected by the maternal diet regime, probably due to varying maternal PUFA provisioning. A low maternal provisioning of EPA or ALA was sufficient to prevent growth limitation of offspring by these PUFAs until reaching maturity. A comparison with results of published ALA and EPA supplementation experiments suggests that the previously observed limitation effects depended on the usage of a single algae genus as maternal diet. Therefore, we suggest that maternal diets should be deliberately varied in future studies assessing ecological relevant food quality effects on zooplankton, especially regarding PUFAs.}, language = {en} } @article{WackerMarzetzSpijkerman2015, author = {Wacker, Alexander and Marzetz, Vanessa and Spijkerman, Elly}, title = {Interspecific competition in phytoplankton drives the availability of essential mineral and biochemical nutrients}, series = {Ecology : a publication of the Ecological Society of America}, volume = {96}, journal = {Ecology : a publication of the Ecological Society of America}, number = {9}, publisher = {Wiley}, address = {Washington}, issn = {0012-9658}, doi = {10.1890/14-1915.1}, pages = {2467 -- 2477}, year = {2015}, abstract = {The underlying mechanisms and consequences of competition and diversity are central themes in ecology. A higher diversity of primary producers often results in higher resource use efficiency in aquatic and terrestrial ecosystems. This may result in more food for consumers on one hand, while, on the other hand, it can also result in a decreased food quality for consumers; higher biomass combined with the same availability of the limiting compound directly reduces the dietary proportion of the limiting compound. Here we tested whether and how interspecific competition in phytoplankton communities leads to changes in resource use efficiency and cellular concentrations of nutrients and fatty acids. The measured particulate carbon : phosphorus ratios (C:P) and fatty acid concentrations in the communities were compared to the theoretically expected ratios and concentrations of measurements on simultaneously running monocultures. With interspecific competition, phytoplankton communities had higher concentrations of the monounsaturated fatty acid oleic acid and also much higher concentrations of the ecologically and physiologically relevant long-chain polyunsaturated fatty acid eicosapentaenoic acid than expected concentrations based on monocultures. Such higher availability of essential fatty acids may contribute to the positive relationship between phytoplankton diversity and zooplankton growth, and may compensate limitations by mineral nutrients in higher trophic levels.}, language = {en} } @article{SchwarzenbergerWacker2015, author = {Schwarzenberger, Anke and Wacker, Alexander}, title = {Melatonin synthesis follows a daily cycle in Daphnia}, series = {Journal of plankton research}, volume = {37}, journal = {Journal of plankton research}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0142-7873}, doi = {10.1093/plankt/fbv029}, pages = {636 -- 644}, year = {2015}, abstract = {In freshwater systems, Daphnia has been demonstrated to show adaptive responses following the light-dark cycle. The adjustment of these responses to the change of day and night is probably transmitted via the hormone melatonin. The rate-limiting enzyme in melatonin synthesis is the arylalkylamine N-transferase (AANAT). We identified three genes coding for insect-like AANATs in Daphnia, of which we measured the gene expression in an ecologically relevant light-dark cycle. We demonstrated that Daphnia's insect-like AANAT gene expression oscillated in a daily manner, and that the highest peak of expression after the onset of darkness was followed by a peak of melatonin production at midnight. Moreover, we could show an oscillation of endogenous melatonin synthesis in Daphnia. In most organisms, melatonin synthesis is due to rhythmic expression of genes of the circadian clock, since transcription of aanats is directly linked to a circadian transcription factor. We could demonstrate that putative clock genes and insect-like AANAT genes of Daphnia were equally expressed. Therefore, we propose that melatonin synthesis is coupled to the expression of Daphnia clock genes, and that insect-like AANATs of crustaceans have a similar function as AANATs of vertebrates: The initiation of melatonin synthesis. In future studies with Daphnia, it will be necessary to take the time of day into account since melatonin concentrations might influence stress responses.}, language = {en} } @article{ZimmermannNey2015, author = {Zimmermann, Andreas and Ney, Martin}, title = {Cyber-Security beyond the military perspective: International Law 'cyber space' and the concept of due diligence.}, series = {German Yearbook of International Law}, volume = {58}, journal = {German Yearbook of International Law}, publisher = {Duncker \& Humblot}, address = {Berlin}, pages = {51 -- 66}, year = {2015}, language = {en} } @article{Zimmermann2015, author = {Zimmermann, Andreas}, title = {The Palestinian-Israeli Conflict: Developing International Law Without Solving the Conflict}, series = {Archiv des V{\"o}lkerrechts}, volume = {53}, journal = {Archiv des V{\"o}lkerrechts}, number = {2}, publisher = {Mohr Siebeck}, address = {T{\"u}bingen}, doi = {10.1628/000389215X14412717564749}, pages = {149 -- 166}, year = {2015}, abstract = {The article analyses whether the Palestinian-Israeli conflict has served as a catalyst for the development of international law, as well as whether international law has been instrumental in attempting to find solutions for the said conflict. In several ways, this conflict has made a significant contribution to understanding and interpreting the UN Charter. It also brought along important developments about the role of third parties, both under the Geneva Conventions and under the law of state responsibility, which provides for an obligation of not recognizing as legal, or not rendering aid or assistance to situations caused by serious violations of jus cogens. International judicial institutions (and also domestic ones) play a rather limited role in this respect, due both to a lack of courage to address fundamental questions, and/or a disregard of the outcome of the proceedings by at least one of the parties to the conflict. Other reasons are Israel's reluctance of accepting the jurisdiction of either the ICJ or the ICC, and its view on the non-applicability of human rights treaties outside of its territory, as well as Palestine's uncertain status in the international community limiting its access to international courts. However, the ICJ's 2004 (formally non-binding) advisory opinion on the Israeli Wall provided answers to some of the most fundamental questions related to the conflict, unfortunately without having any immediate impact on the situation on the ground. Given Palestine's accession to the Rome Statute in early 2015, time has yet to show which role in the process will be played by the ICC. Other issues arising from the conflict, and examined by this article, are that of (Palestinian) statehood, going beyond the traditional concept of statehood and including the consequences of the jus cogens-character of the right of self-determination, as well as questions of treaty succession and succession in matters of State responsibility with regard to acts committed by the PLO.}, language = {en} } @article{MegowKoerzdoerferRengeretal.2015, author = {Megow, J{\"o}rg and K{\"o}rzd{\"o}rfer, Thomas and Renger, Thomas and Sparenberg, Mino and Blumstengel, Sylke and Henneberger, Fritz and May, Volkhard}, title = {Calculating Optical Absorption Spectra of Thin Polycrystalline Organic Films: Structural Disorder and Site-Dependent van der Waals Interaction}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {119}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {10}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5b01587}, pages = {5747 -- 5751}, year = {2015}, abstract = {We propose a new approach for calculating the change of the absorption spectrum of a molecule when moved from the gas phase to a crystalline morphology. The so-called gas-to-crystal shift Delta epsilon(m) is mainly caused by dispersion effects and depends sensitively on the molecules specific position in the nanoscopic setting. Using an extended dipole approximation, we are able to divide Delta epsilon(m)= -QW(m) in two factors, where Q depends only on the molecular species and accounts for all nonresonant electronic transitions contributing to the dispersion while W-m is a geometry factor expressing the site dependence of the shift in a given molecular structure. The ability of our approach to predict absorption spectra is demonstrated using the example of polycrystalline films of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI).}, language = {en} } @article{EgbertGiest2015, author = {Egbert, Bj{\"o}rn and Giest, Hartmut}, title = {Lernen ohne Anschluss}, series = {Allgemeinbildung und Curriculumentwicklung : Herrausforderung an das Fach Wirtschaft - Arbeit - Technik}, journal = {Allgemeinbildung und Curriculumentwicklung : Herrausforderung an das Fach Wirtschaft - Arbeit - Technik}, editor = {Meier, Bernd and Banse, Gerhard}, publisher = {Lang}, address = {Berlin}, isbn = {978-3-631-66541-1}, pages = {147 -- 163}, year = {2015}, language = {de} } @article{RenzOttenFaurobertetal.2015, author = {Renz, Marc and Otten, Cecile and Faurobert, Eva and Rudolph, Franziska and Zhu, Yuan and Boulday, Gwenola and Duchene, Johan and Mickoleit, Michaela and Dietrich, Ann-Christin and Ramspacher, Caroline and Steed, Emily and Manet-Dupe, Sandra and Benz, Alexander and Hassel, David and Vermot, Julien and Huisken, Jan and Tournier-Lasserve, Elisabeth and Felbor, Ute and Sure, Ulrich and Albiges-Rizo, Corinne and Abdelilah-Seyfried, Salim}, title = {Regulation of beta 1 Integrin-Klf2-Mediated angiogenesis by CCM proteins}, series = {Developmental cell}, volume = {32}, journal = {Developmental cell}, number = {2}, publisher = {Cell Press}, address = {Cambridge}, issn = {1534-5807}, doi = {10.1016/j.devcel.2014.12.016}, pages = {181 -- 190}, year = {2015}, abstract = {Mechanotransduction pathways are activated in response to biophysical stimuli during the development or homeostasis of organs and tissues. In zebrafish, the blood-flow-sensitive transcription factor Klf2a promotes VEGF-dependent angiogenesis. However, the means by which the Klf2a mechanotransduction pathway is regulated to prevent continuous angiogenesis remain unknown. Here we report that the upregulation of klf2 mRNA causes enhanced egfl7 expression and angiogenesis signaling, which underlies cardiovascular defects associated with the loss of cerebral cavernous malformation (CCM) proteins in the zebrafish embryo. Using CCM-protein-depleted human umbilical vein endothelial cells, we show that the misexpression of KLF2 mRNA requires the extracellular matrix-binding receptor beta 1 integrin and occurs in the absence of blood flow. Downregulation of beta 1 integrin rescues ccm mutant cardiovascular malformations in zebrafish. Our work reveals a beta 1 integrin-Klf2-Egfl7-signaling pathway that is tightly regulated by CCM proteins. This regulation prevents angiogenic overgrowth and ensures the quiescence of endothelial cells.}, language = {en} } @article{LombardoOttenAbdelilahSeyfried2015, author = {Lombardo, Veronica A. and Otten, Cecile and Abdelilah-Seyfried, Salim}, title = {Large-scale Zebrafish Embryonic Heart Dissection for Transcriptional Analysis}, series = {Journal of visualized experiments}, journal = {Journal of visualized experiments}, number = {95}, publisher = {JoVE}, address = {Cambridge}, issn = {1940-087X}, doi = {10.3791/52087}, pages = {7}, year = {2015}, abstract = {The zebrafish embryonic heart is composed of only a few hundred cells, representing only a small fraction of the entire embryo. Therefore, to prevent the cardiac transcriptome from being masked by the global embryonic transcriptome, it is necessary to collect sufficient numbers of hearts for further analyses. Furthermore, as zebrafish cardiac development proceeds rapidly, heart collection and RNA extraction methods need to be quick in order to ensure homogeneity of the samples. Here, we present a rapid manual dissection protocol for collecting functional/beating hearts from zebrafish embryos. This is an essential prerequisite for subsequent cardiac-specific RNA extraction to determine cardiac-specific gene expression levels by transcriptome analyses, such as quantitative real-time polymerase chain reaction (RT-qPCR). The method is based on differential adhesive properties of the zebrafish embryonic heart compared with other tissues; this allows for the rapid physical separation of cardiac from extracardiac tissue by a combination of fluidic shear force disruption, stepwise filtration and manual collection of transgenic fluorescently labeled hearts.}, language = {en} }