Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

© 2016 The Authors.Fluorescent proteins and dyes are routine tools for biological research to describe the behavior of genes, proteins, and cells, as well as more complex physiological dynamics such as vessel permeability and pharmacokinetics. The use of these probes in whole body in vivo imaging would allow extending the range and scope of current biomedical applications and would be of great interest. In order to comply with a wide variety of application demands, in vivo imaging platform requirements span from wide spectral coverage to precise quantification capabilities. Fluorescence molecular tomography (FMT) detects and reconstructs in three dimensions the distribution of a fluorophore in vivo. Noncontact FMT allows fast scanning of an excitation source and noninvasive measurement of emitted fluorescent light using a virtual array detector operating in free space. Here, a rigorous process is defined that fully characterizes the performance of a custom-built horizontal noncontact FMT setup. Dynamic range, sensitivity, and quantitative accuracy across the visible spectrum were evaluated using fluorophores with emissions between 520 and 660 nm. These results demonstrate that high-performance quantitative three-dimensional visible light FMT allowed the detection of challenging mesenteric lymph nodes in vivo and the comparison of spectrally distinct fluorescent reporters in cell culture

Life-cycle analysis of coesite-bearing garnet

Detrital coesite-bearing garnet is the final product of a complex geological cycle including coesite entrapment at ultrahigh-pressure conditions, exhumation to Earth’s surface, erosion, and sedimentary transport. In contrast to the usual enrichment of high-grade metamorphic garnet in 14 medium- to coarse-sand fractions, coesite-bearing grains are often enriched in the very fine-sand fraction. To understand this imbalance, we analyze the role of source rock lithology, inclusion size, inclusion frequency, and fluid infiltration on the grain-size heterogeneity of coesite-bearing garnet based on a dataset of 2100 inclusion-bearing grains, of which 93 contain coesite, from the Saxonian Erzgebirge, Germany. By combining inclusion assemblages and garnet chemistry, we show that mafic garnet contains a low number of coesite inclusions per grain and is enriched in the coarse fraction, and felsic garnet contains variable amounts of coesite inclusions per grain, whereby coesite-poor grains are enriched in the coarse fraction and coesite-rich grains extensively disintegrated into smaller fragments resulting in an enrichment in the fine fraction. Raman images reveal that small coesite inclusions <9 µm are primarily monomineralic, whereas larger inclusions partially transformed to quartz, and garnet fracturing, fluid infiltration, and the coesite-to-quartz transformation is a late process during exhumation taking place at ~330°C. A model for the disintegration of coesite-bearing garnet enables explaining the heterogeneous grain27 size distribution by inclusion frequency. High abundances of coesite inclusions cause a high degree of fracturing and fracture connections to smaller inclusions, allowing fluid infiltration and the transformation to quartz, which in turn further promotes garnet disintegration

Garnet major‑element composition as an indicator of host‑rock type: a machine learning approach using the random forest classifier

The major-element chemical composition of garnet provides valuable petrogenetic information, particularly in metamorphic rocks. When facing detrital garnet, information about the bulk-rock composition and mineral paragenesis of the initial garnet-bearing host-rock is absent. This prevents the application of chemical thermo-barometric techniques and calls for quantitative empirical approaches. Here we present a garnet host-rock discrimination scheme that is based on a random forest machine-learning algorithm trained on a large dataset of 13,615 chemical analyses of garnet that covers a wide variety of garnet-bearing lithologies. Considering the out-of-bag error, the scheme correctly predicts the original garnet host-rock in (i) > 95% concerning the setting, that is either mantle, metamorphic, igneous, or metasomatic; (ii) > 84% concerning the metamorphic facies, that is either blueschist/greenschist, amphibolite, granulite, or eclogite/ultrahigh-pressure; and (iii) > 93% concerning the host-rock bulk composition, that is either intermediate–felsic/metasedimentary, mafic, ultramafic, alkaline, or calc–silicate. The wide coverage of potential host rocks, the detailed prediction classes, the high discrimination rates, and the successfully tested real-case applications demonstrate that the introduced scheme overcomes many issues related to previous schemes. This highlights the potential of transferring the applied discrimination strategy to the broad range of detrital minerals beyond garnet. For easy and quick usage, a freely accessible web app is provided that guides the user in five steps from garnet composition to prediction results including data visualization

Detrital garnet petrology challenges Paleoproterozoic ultrahigh-pressure metamorphism in western Greenland

Modern-style plate tectonics is characterised by the global operation of cold and deep subduction involving blueschist facies and ultrahigh-pressure metamorphism. This has been a common process since the Neoproterozoic, but a couple of studies indicate similar processes were active in the Paleoproterozoic, at least on the local scale. Particularly conspicuous are extreme ultrahigh-pressure conditions of ∼ 7 GPa at thermal gradients &lt; 150 ∘C GPa−1 proposed for metamorphic rocks of the Nordre Strømfjord shear zone in the western part of the Paleoproterozoic Nagssugtoqidian Orogen of Greenland. By acquiring a large dataset of heavy minerals (n = 52 130) and garnet major-element composition integrated with mineral inclusion analysis (n=2669) from modern sands representing fresh and naturally mixed erosional material from the metamorphic rocks, we here intensely screened the area for potential occurrences of ultrahigh-pressure rocks and put constraints on the metamorphic evolution. Apart from the absence of any indications pointing to ultrahigh-pressure and low-temperature–high-pressure metamorphism, the results are well in accordance with a common Paleoproterozoic subduction–collision metamorphic evolution along a Barrovian-type intermediate temperature and pressure gradient with a pressure peak at the amphibolite–granulite–eclogite-facies transition and a temperature peak at medium- to high-pressure granulite-facies conditions. In addition, we discuss that all “evidence” for ultrahigh-pressure metamorphism proposed in the literature for rocks of this area is equivocal. Accordingly, the Nordre Strømfjord shear zone is not an example of modern-style plate tectonics in the Paleoproterozoic or of very low thermal gradients and extreme pressure conditions in general.</p

Tetracycline Inducible Gene Manipulation in Serotonergic Neurons

The serotonergic (5-HT) neuronal system has important and diverse physiological functions throughout development and adulthood. Its dysregulation during development or later in adulthood has been implicated in many neuropsychiatric disorders. Transgenic animal models designed to study the contribution of serotonergic susceptibility genes to a pathological phenotype should ideally allow to study candidate gene overexpression or gene knockout selectively in serotonergic neurons at any desired time during life. For this purpose, conditional expression systems such as the tet-system are preferable. Here, we generated a transactivator (tTA) mouse line (TPH2-tTA) that allows temporal and spatial control of tetracycline (Ptet) controlled transgene expression as well as gene deletion in 5-HT neurons. The tTA cDNA was inserted into a 196 kb PAC containing a genomic mouse Tph2 fragment (177 kb) by homologous recombination in E. coli. For functional analysis of Ptet-controlled transgene expression, TPH2-tTA mice were crossed to a Ptet-regulated lacZ reporter line (Ptet-nLacZ). In adult double-transgenic TPH2-tTA/Ptet-nLacZ mice, TPH2-tTA founder line L62-20 showed strong serotonergic β-galactosidase expression which could be completely suppressed with doxycycline (Dox). Furthermore, Ptet-regulated gene expression could be reversibly activated or inactivated when Dox was either withdrawn or added to the system. For functional analysis of Ptet-controlled, Cre-mediated gene deletion, TPH2-tTA mice (L62-20) were crossed to double transgenic Ptet-Cre/R26R reporter mice to generate TPH2-tTA/Ptet-Cre/R26R mice. Without Dox, 5-HT specific recombination started at E12.5. With permanent Dox administration, Ptet-controlled Cre-mediated recombination was absent. Dox withdrawal either postnatally or during adulthood induced efficient recombination in serotonergic neurons of all raphe nuclei, respectively. In the enteric nervous system, recombination could not be detected. We generated a transgenic mouse tTA line (TPH2-tTA) which allows both inducible and reversible transgene expression and inducible Cre-mediated gene deletion selectively in 5-HT neurons throughout life. This will allow precise delineation of serotonergic gene functions during development and adulthood

Afrikaans as Standaard Gemiddelde Europees:Wanneer ‘n lid uit sy taalarea beweeg

A recent trend in the study of Standard Average European is the extraterritorial perspective of examining the extent to which non-European languages have converged with this Sprachbund as a result of contact with one or more of its members. The present article complements this line of research in that it investigates the extent to which a European language has diverged from Standard Average European after leaving the linguistic area. The focus is on Dutch, a nuclear member of the Sprachbund, and Afrikaans, its colonial offshoot. The two languages are compared with respect to twelve of the most distinctive linguistic features of Standard Average European. Afrikaans is found to share ten of them with Dutch, including anticausative prominence and formally distinguished intensifiers and reflexives, and could therefore still be considered a core member of the Sprachbund, despite deviations in the expression of negative pronouns and the grammaticality of external possessor constructions. This relatively low degree of divergence may be attributed to the continuity from Settler Dutch to at least the variety of Afrikaans on which the standard language is based and to the important role that Dutch continued to play in the history of Afrikaans

Hyperoxia but not AOX expression mitigates pathological cardiac remodeling in a mouse model of inflammatory cardiomyopathy

Constitutive expression of the chemokine Mcp1 in mouse cardiomyocytes creates a model of inflammatory cardiomyopathy, with death from heart failure at age 7-8 months. A critical pathogenic role has previously been proposed for induced oxidative stress, involving NADPH oxidase activation. To test this idea, we exposed the mice to elevated oxygen levels. Against expectation, this prevented, rather than accelerated, the ultrastructural and functional signs of heart failure. This result suggests that the immune signaling initiated by Mcp1 leads instead to the inhibition of cellular oxygen usage, for which mitochondrial respiration is an obvious target. To address this hypothesis, we combined the Mcp1 model with xenotopic expression of the alternative oxidase (AOX), which provides a sink for electrons blocked from passage to oxygen via respiratory complexes III and IV. Ubiquitous AOX expression provided only a minor delay to cardiac functional deterioration and did not prevent the induction of markers of cardiac and metabolic remodeling considered a hallmark of the model. Moreover, cardiomyocyte-specific AOX expression resulted in exacerbation of Mcp1-induced heart failure, and failed to rescue a second cardiomyopathy model directly involving loss of cIV. Our findings imply that mitochondria! involvement in the pathology of inflammatory cardiomyopathy is multifaceted and complex.Peer reviewe