89 research outputs found

    Preference for C 4 shade grasses increases hatchling performance in the butterfly, Bicyclus safitza

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    The Miocene radiation of C4 grasses under high-temperature and low ambient CO2 levels occurred alongside the transformation of a largely forested landscape into savanna. This inevitably changed the host plant regime of herbivores, and the simultaneous diversification of many consumer lineages, including Bicyclus butterflies in Africa, suggests that the radiations of grasses and grazers may be evolutionary linked. We examined mechanisms for this plant–herbivore interaction with the grass-feeding Bicyclus safitza in South Africa. In a controlled environment, we tested oviposition preference and hatchling performance on local grasses with C3 or C4 photosynthetic pathways that grow either in open or shaded habitats. We predicted preference for C3 plants due to a hypothesized lower processing cost and higher palatability to herbivores. In contrast, we found that females preferred C4 shade grasses rather than either C4 grasses from open habitats or C3 grasses. The oviposition preference broadly followed hatchling performance, although hatchling survival was equally good on C4 or C3 shade grasses. This finding was explained by leaf toughness; shade grasses were softer than grasses from open habitats. Field monitoring revealed a preference of adults for shaded habitats, and stable isotope analysis of field-sampled individuals confirmed their preference for C4 grasses as host plants. Our findings suggest that plant–herbivore interactions can influence the direction of selection in a grass-feeding butterfly. Based on this work, we postulate future research to test whether these interactions more generally contribute to radiations in herbivorous insects via expansions into new, unexploited ecological niches

    Analysis of the expression patterns, subcellular localisations and interaction partners of Drosophila proteins using a pigP protein trap library.

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    Although we now have a wealth of information on the transcription patterns of all the genes in the Drosophila genome, much less is known about the properties of the encoded proteins. To provide information on the expression patterns and subcellular localisations of many proteins in parallel, we have performed a large-scale protein trap screen using a hybrid piggyBac vector carrying an artificial exon encoding yellow fluorescent protein (YFP) and protein affinity tags. From screening 41 million embryos, we recovered 616 verified independent YFP-positive lines representing protein traps in 374 genes, two-thirds of which had not been tagged in previous P element protein trap screens. Over 20 different research groups then characterized the expression patterns of the tagged proteins in a variety of tissues and at several developmental stages. In parallel, we purified many of the tagged proteins from embryos using the affinity tags and identified co-purifying proteins by mass spectrometry. The fly stocks are publicly available through the Kyoto Drosophila Genetics Resource Center. All our data are available via an open access database (Flannotator), which provides comprehensive information on the expression patterns, subcellular localisations and in vivo interaction partners of the trapped proteins. Our resource substantially increases the number of available protein traps in Drosophila and identifies new markers for cellular organelles and structures.This work was supported by a project grant from the Wellcome Trust [076739], by a Wellcome Trust Principal Research Fellowship to D.StJ. [049818 and 080007], and by core support from the Wellcome Trust [092096] and Cancer Research UK [A14492].This is the final version of the article. It was first available from The Company of Biologists via http://dx.doi.org/10.1242/dev.11105

    The Astropy Problem

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    The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Despite this, the project has always been and remains to this day effectively unfunded. Further, contributors receive little or no formal recognition for creating and supporting what is now critical software. This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software

    Brf1 loss and not overexpression disrupts tissues homeostasis in the intestine, liver and pancreas

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    RNA polymerase III (Pol-III) transcribes tRNAs and other small RNAs essential for protein synthesis and cell growth. Pol-III is deregulated during carcinogenesis; however, its role in vivo has not been studied. To address this issue, we manipulated levels of Brf1, a Pol-III transcription factor that is essential for recruitment of Pol-III holoenzyme at tRNA genes in vivo. Knockout of Brf1 led to embryonic lethality at blastocyst stage. In contrast, heterozygous Brf1 mice were viable, fertile and of a normal size. Conditional deletion of Brf1 in gastrointestinal epithelial tissues, intestine, liver and pancreas, was incompatible with organ homeostasis. Deletion of Brf1 in adult intestine and liver induced apoptosis. However, Brf1 heterozygosity neither had gross effects in these epithelia nor did it modify tumorigenesis in the intestine or pancreas. Overexpression of BRF1 rescued the phenotypes of Brf1 deletion in intestine and liver but was unable to initiate tumorigenesis. Thus, Brf1 and Pol-III activity are absolutely essential for normal homeostasis during development and in adult epithelia. However, Brf1 overexpression or heterozygosity are unable to modify tumorigenesis, suggesting a permissive, but not driving role for Brf1 in the development of epithelial cancers of the pancreas and gut

    Gastrolithiasis in prehensile-tailed porcupines (Coendou prehensilis): Nine cases and pathogenesis of stone formation

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    Gastrolithiasis was diagnosed in nine prehensile-tailed (PT) porcupines (Coendou prehensilis) housed at six zoologic institutions in the United States and Canada. Affected animals were either asymptomatic or had clinical signs, including weight loss, diarrhea, and depression. Abdominal palpation was adequate for diagnosis in all six antemortem cases, and radiographs confirmed a soft tissue density mass effect produced by the concretion. These gastroliths were all successfully surgically removed. Recurrence of gastrolith formation was common and occurred in four of the cases. Three cases were diagnosed postmortem, with the gastrolith causing gastric perforation in one case. Gastroliths from four cases were identified by mass spectrometry as bile acid precipitates consisting of the insoluble acid form of endogenous glycine-conjugated bile acids

    In vivo analysis of a genetically modified adenoviral vector targeted to human CD40 using a novel transient transgenic model

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    Copyright © 2005 John Wiley & Sons, Ltd.BackgroundRetargeting is necessary to overcome the limitations of adenovirus (Ad)-based gene therapy vectors. To this end, we previously constructed an adenovirus with the fiber knob domain replaced by a fibritin trimerization motif fused to the CD40 ligand (Ad5Luc.FF/CD40L). We demonstrated the utility of this fiber replacement strategy for targeting CD40 (hCD40) on human dendritic cells in vitro. The in vivo targeting capacity of this virus, however, is unknown, and there is a limited repertoire of animal models that present hCD40 at an accessible site. Therefore, a new animal model for evaluating CD40-targeted vectors is required.MethodsWe constructed a recombinant adenovirus that expresses hCD40 under transcriptional control of the flt-1 promoter (AdflthCD40). Expression of hCD40 was validated both in vitro and in transgenic mice expressing the human coxsackie adenovirus receptor (hCAR mice). We then evaluated the targeting efficiency of Ad5Luc.FF/CD40L to hCD40 expressed in the pulmonary vasculature of the hCAR mice.ResultsInfection of flt-1-positive cells with AdflthCD40 resulted in abundant hCD40 expression in vitro, which could subsequently be targeted by Ad5Luc.FF/CD40L. In vivo administration of AdflthCD40 to hCAR mice resulted in hCD40 expression in the pulmonary vasculature, which was successfully targeted with systemically administered Ad5Luc.FF/CD40L.ConclusionsThis is the first data showing that genetically modified Ad5Luc.FF/CD40L can successfully target hCD40 in vivo. Our data also establishes the utility of transcriptionally targeted, Ad-mediated transient expression of human target molecules in the pulmonary vasculature of hCAR mice as models for in vivo analysis of targeted gene therapy vectors.Miiru Izumi, Yosuke Kawakami, Joel N. Glasgow, Natalya Belousova, Maaike Everts, SangAe Kim-Park, Seiji Yamamoto, Minghui Wang, Long P. Le, Paul N. Reynolds, David T. Curie
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