A Technical Note on Quantum Dots for Multi-Color Fluorescence in situ Hybridization

Quantum dots (Qdots) are semiconductor nanocrystals, which are photo-stable, show bright fluorescence with narrow, symmetric emission spectra and are available in multiple resolvable colors. We established a FISH protocol for the simultaneous visualization of up to 6 different DNA probes differentially labeled with Qdots and with conventional organic fluorochromes. Using a Leica SP5 laser scanning confocal microscope for image capture, we tested various combinations of hapten-labeled probes detected with streptavidin-Qdot525, sheep anti-digoxigenin-Qdot605, rat anti-dinitrophenyl-Qdot655 and goat anti-mouse-Qdot655, respectively, together with FITC-dUTP-, Cy3-dUTP- and Texas Red-dUTP-labeled probes. We further demonstrate that Qdots are suitable for imaging of FISH probes using 4Pi microscopy, which promises to push the resolution limits of light microscopy to 100 nanometers or less when applying a deconvolution algorithm, but requires the use of highly photo-stable fluors. Copyright (C) 2009 S. Karger AG, Base

The Impact of Scarcity Messages on the Online Sales of Physical Information Goods

For physical consumer goods with no considerable information component, past research has identified scarcity, due to market conditions or as a producer strategy, as a driver of intention to purchase and willingness to pay. In contrast, information as the major value-creating component of physical information goods is inherently non-scarce. While anecdotal evidence suggests that intended or unintended scarcity can benefit sales of physical information goods, the underlying mechanisms have not been systematically investigated so far. To close this gap, this research develops a model based on an extensive literature review. The model is tested against evidence from e-commerce sales data of 34,748 information goods. We find that quantity-based scarcity overall decreases sales, but is associated with an increase in the quantity purchased among all purchasing customers. We discuss implications for theory development around the scarcification of information

Predicting Popularity of Hedonic Digital Content via Artificial Intelligence Imagery Analysis of Thumbnails

Hedonic digital content backs a wide variety of business models. Yet, due to its experience good nature, consumers cannot assess its value before consumption. To overcome this obstacle, thumbnail images are frequently employed to provide an experience of content, and trigger views and sales. In spite of fragmented evidence from human-computer interaction research, thumbnails largely constitute a black box for research and practice. This research aims to fill this gap and asks: How and why do basic, conceptual and social features of thumbnail images affect popularity of hedonic digital content? To answer the question, we employ artificial intelligence imagery analysis to test and confirm a variance model against evidence from 400,000 YouTube videos. Our findings entail important theoretical contributions to visual perception in online contexts. In addition, this research proposes artificial intelligence imagery analysis as a new and fruitful research method for the largely visual information systems discipline

Towards many colors in FISH on 3D-preserved interphase nuclei

The article reviews the existing methods of multicolor FISH on nuclear targets, first of all, interphase chromosomes. FISH proper and image acquisition are considered as two related components of a single process. We discuss (1) M-FISH (combinatorial labeling + deconvolution + widefield microscopy); (2) multicolor labeling + SIM (structured illumination microscopy); (3) the standard approach to multicolor FISH + CLSM (confocal laser scanning microscopy; one fluorochrome - one color channel); (4) combinatorial labeling + CLSM; (5) non-combinatorial labeling + CLSM + linear unmixing. Two related issues, deconvolution of images acquired with CLSM and correction of data for chromatic Z-shift, are also discussed. All methods are illustrated with practical examples. Finally, several rules of thumb helping to choose an optimal labeling + microscopy combination for the planned experiment are suggested. Copyright (c) 2006 S. Karger AG, Basel

Detection of amplified DNA sequences by reverse chromosome painting using genomic tumor DNA as probe

A modification of reverse chromosome painting was carried out using genomic DNA from tumor cells as a complex probe for chromosomal in situ suppression hybridization to normal metaphase chromsome spreads. Amplified DNA sequences contained in such probes showed specific signals, revealing the normal chromosome positions from which these sequences were derived. As a model system, genomic DNAs were analyzed from three tumor cell lines with amplification units including the proto-oncogene c-myc. The smallest amplification unit was about 90 kb and was present in 16–24 copies; the largest unit was bigger than 600 kb and was present in 16–32 copies. Specific signals that co-localized with a differently labeled c-myc probe on chromosome band 8q24 were obtained with genomic DNA from each cell line. In further experiments, genomic DNA derived from primary tumor material was used in the case of a male patient with glioblastoma multiforme (GBM). Southern blot analysis using an epidermal growth factor receptor gene (EGFR) probe that maps to 7p13 indicated the amplification of sequences from this gene. Using reverse chromosome painting, signals were found both on band 7p13 and bands 12q13–q15. Notably, the signal on 12q13–q15 was consistently stronger. The weaker 7p13 signal showed co-localization with the major signal of the differently labeled EGFR probe. A minor signal of this probe was seen on 12q13, suggesting cross-hybridization to ERB3 sequences homologous to EGFR. The results indicate co-amplification of sequences from bands 12q13–q15, in addition to sequences from band 7p13. Several oncogenes map to 12q13–q15 providing candidate genes for a tumor-associated proto-oncogene amplification. Although the nature of the amplified sequences needs to be clarified, this experiment demonstrates the potential of reverse chromosome painting with genomic tumor DNA for rapidly mapping the normal chromosomal localization of the DNA from which the amplified sequences were derived. In addition, a weaker staining of chromosomes 10 and X was consistently observed indicating that these chromosomes were present in only one copy in the GBM genome. This rapid approach can be used to analyze cases where no metaphase spreads from the tumor material are available. It does not require any preknowledge of amplified sequences and can be applied to screen large numbers of tumors

ICT for Economic Development in Rwanda: Fostering E-Commerce Adoption in Tourism SMEs

Small and Medium Enterprises (SMEs) in the Rwandan tourism sector are slow in adopting information and communication technology (ICT) and especially e-commerce applications (Nibigira 2014). In the effort to pinpoint the drivers promising more extensive EC roll-out and thus economic and societal ICT-driven improvements in Rwanda, we firstly show some ongoing initiatives that of deploying ICT and e-commerce Rwanda. We then investigate more specifically the key determinants of EC adoption in the context of Rwanda. To that end, we adopt the Perceived E-Readiness Model (PERM) developed by Molla and Licker (2005) and apply it to ecommerce adoption in Rwandan tourism SMEs. From better understanding what accelerates or impedes ICT and e-commerce adoption in the Rwandan tourism sector, we hope to derive arguments for further fostering ICT roll-out in general and the e-commerce roll-out in particular in Rwanda – first throughout the Rwandan tourism sector and subsequently throughout other SME-based business sectors – and thus to contribute to the country\u27s economic and societal development along the lines of many Information and Communication Technology for Development (ICT4D) studies (Heeks 2006, Heeks and Molla 2007, Zelenika and Pearce 2013)

Complete Genome Sequence from an Uncultivated Freshwater Elusimicrobiota Lineage

Here, we report the first complete genome of an uncultivated freshwater Elusimicrobiota organism recovered from a nonaxenic Amoebozoa sp. culture. The chromosome was obtained from a metagenomic long-read sequencing run and was assembled as a circular element at a 47× coverage, a length of 3.8 Mbp, and a G+C content of 68.6%

Influence of fluoride on the mineralization of collagen via the polymer-induced liquid-precursor (PILP) process.

ObjectiveThe polymer-induced liquid-precursor (PILP) mineralization process has been shown to remineralize artificial dentin lesions to levels consistent with those of native dentin. However, nanoindentation revealed that the moduli of those remineralized lesions were only ∼50% that of native dentin. We hypothesize that this may be due to the PILP process having been previously optimized to obtain high amounts (∼70wt%) of intrafibrillar crystals, but without sufficient interfibrillar mineral, another significant component of dentin.MethodsFluoride was added to the PILP-mineralization of collagen from rat tail tendon at varying concentrations to determine if a better balance of intra- versus inter-fibrillar mineralization could be obtained, as determined by electron microscopy. Nanoindentation was used to determine if fluoridated apatite could improve the mechanical properties of the composites.ResultsFluoride was successfully incorporated into the PILP-mineralization of rat tail tendon and resulted in collagen-mineral composite systems with the mineral phase of hydroxyapatite containing various levels of fluoridation. As the fluoride concentration increased, the crystals became larger and more rod-like, with an increasing tendency to form on the fibril surfaces rather than the interior. Nanomechanical testing of the mineralized tendons revealed that fluoride addition did not increase modulus over PILP mineralization alone. This likely resulted from the separated nature of collagen fibrils that comprise tendon, which does not provide lateral reinforcement and therefore may not be suited for the compressive loads of nanoindentation.SignificanceThis work contributes to the development of minimally invasive approaches to caries treatment by determining if collagen can be functionally mineralized