Platelets at the vascular interface

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Platelet signaling--blood's great balancing act

The antagonistic balance between CalDAG-GEFI and RASA3 signaling is critical for the fine-tuning of platelet adhesiveness, both in the circulation and at sites of vascular injury

Panorama imaging for image-to-physical registration of narrow drill holes inside spongy bones

Image-to-physical registration based on volumetric data like computed tomography on the one side and intraoperative endoscopic images on the other side is an important method for various surgical applications. In this contribution, we present methods to generate panoramic views from endoscopic recordings for image-to-physical registration of narrow drill holes inside spongy bone. One core application is the registration of drill poses inside the mastoid during minimally invasive cochlear implantations. Besides the development of image processing software for registration, investigations are performed on a miniaturized optical system, achieving 360° radial imaging with one shot by extending a conventional, small, rigid, rod lens endoscope. A reflective cone geometry is used to deflect radially incoming light rays into the endoscope optics. Therefore, a cone mirror is mounted in front of a conventional 0° endoscope. Furthermore, panoramic images of inner drill hole surfaces in artificial bone material are created. Prior to drilling, cone beam computed tomography data is acquired from this artificial bone and simulated endoscopic views are generated from this data. A qualitative and quantitative image comparison of resulting views in terms of image-to-image registration is performed. First results show that downsizing of panoramic optics to a diameter of 3mm is possible. Conventional rigid rod lens endoscopes can be extended to produce suitable panoramic one-shot image data. Using unrolling and stitching methods, images of the inner drill hole surface similar to computed tomography image data of the same surface were created. Registration is performed on ten perturbations of the search space and results in target registration errors of (0:487 ± 0:438)mm at the entry point and (0:957 ± 0:948)mm at the exit as well as an angular error of (1:763 ± 1:536)°. The results show suitability of this image data for image-to-image registration. Analysis of the error components in different directions reveals a strong influence of the pattern structure, meaning higher diversity results into smaller errors. © 2017 SPIE

From shallow sands to deep-sea trenches: Towards integrative systematics of Solenogastres (Aplacophora, Mollusca)

The marine realm encompasses a plethora of habitats: from light-flooded tropical coral reefs down to chemosynthetic vents and seeps to oceanic trenches several kilometers below the ocean’s surface. Habitat destruction, pollution, and effects of climate change accelerate rates of species extinction and pose a massive threat to marine ecosystems and biodiversity. Lack of baseline knowledge on species diversity is the key shortfall of current biodiversity research and especially prevalent among small-size invertebrates which constitute the larger part of global, metazoan biodiversity. Solenogastres (or Neomeniomorpha), an enigmatic class of molluscs are one of those understudied and neglected marine taxa. Instead of bearing a shell, these worm-shaped molluscs are densely covered in aragonitic spicules (the scleritome). They have been found from the tropics to the poles and occur from shallow waters down to the deep sea, with a peak in diversity along the continental shelfs. Despite their circumglobal occurrence, less than 300 species of Solenogastres have been described during the last 150 years since their first discovery. However, natural history collections alone have been estimated to contain at least ten-times more undescribed species than are currently known. Taxonomy of Solenogastres is bulky, requiring a mosaic of morphological and anatomical characters even for higher classification and is thus considered notoriously complex among zoologists. Novel approaches to characterize solenogaster diversity are urgently needed in order to catch up with discovery rates and modernize the taxonomic process. During my dissertation, I aimed to explore the diversity and evolution of Solenogastres in two understudied marine environments: the shallow-water interstitial habitat (i.e. the pore spaces between sand grains) and the deep oceans beyond the bathyal zone. For this purpose, I developed a novel integrative taxonomic workflow combining morphological characters of traditional taxonomy with DNA barcoding for molecular approaches to species delineation, supplemented with state-of-the-art anatomical 3D reconstructions of selected key lineages. My dissertation research is based on Solenogastres collected by colleagues and myself during sampling trips targeting marine interstitial malacofauna in Bermuda, Hawaii, Azores, Honshu and Okinawa (Japan). I joined two out of a series of four international deep-sea expeditions collecting benthic fauna in the Northwest Pacific, sampling across a depth range from 1,600 m down to almost 10,000 m in the Kuril-Kamchatka Trench. Overall, these expeditions covered different areas in the Northwest Pacific of varying geological age and stages of isolation. Additional material was made available through the natural history collection of the Section Mollusca, Bavarian State Collection of Zoology (SNSB-ZSM München), resulting in a total of 347 Solenogastres investigated during the course of my dissertation. Based on my work we are now able to identify main clades of meiofaunal Solenogastres, in a first step towards elucidating their global diversity of the clade in the interstitial habitat. The discovery of a putative widely distributed mesopsammic lineage of Dondersiidae (order Pholidoskepia) at sampling sites in the Atlantic and Pacific is challenged by the presence of co-occurring morphologically cryptic species revealed through anatomical 3D reconstructions. This highlights 1.) the risk of chimeric species descriptions if several individuals are used to extract all sets of taxonomically relevant characters and 2.) the importance of molecular data to reliably test hypothesis on conspecificity and distribution patterns in this taxonomically challenging group. Northwest Pacific Solenogastres were delineated based on unique morphological characters (i.e. scleritome data) and, if possible, cross-validated via molecular-based phylogenetic analyses. This integrative approach resulted in 60 candidate species across regions and depth zones in the Northwest Pacific (additional 13 candidate species lack molecular data), with the majority constituting species new to science. Their diversity covers all four orders, at least nine families, and 15 genera – therein presenting an immense boost in regional diversity. On a global scale, the number of abyssal Solenogastres has been more than doubled by these studies, and the animals collected from the bottom of the Kuril-Kamchatka Trench provide the first evidence of this molluscan class from the hadal zone and hold its depth record at almost 10,000 meters. The established baseline dataset of alpha-diversity from adjacent areas and depths zones enabled a first glimpse into distribution patterns. While there was overall little faunal overlap between the investigated regions and depths, several unique links were revealed: 1.) across depth by an eurybathic species occurring in the Kuril Basin (3,350 m) and at the bottom of the trench (9,580 m); 2) across the Kuril-Kamchatka Trench: Kruppomenia genslerae Ostermair, Brandt, Haszprunar, Jörger & Bergmeier, 2018 was found in the Sea of Okhotsk and on the open abyssal plain, thereby indicating that a hadal trench does not pose an insurmountable dispersal barrier for benthic invertebrates; and 3) potentially across oceans: anatomical investigations suggest that an abyssal species from the Atlantic is also present on the Northwest Pacific Plain, albeit molecular data from the putative Atlantic conspecifics to support pan-oceanic distribution is lacking. In order to gain insights into the feeding ecology of deep-sea Solenogastres, we sequenced their gut contents from genomic DNA extracts. This molecular-based approach showed that they are highly specialized micropredators with taxon-specific prey preferences. While anthozoan and hydrozoan cnidarians have been generally assumed as the main food source of Solenogastres, Siphonophora, Nemertea, Annelida and Bivalvia have now been added to their menu. The molecular phylogeny used as a backbone for our integrative approach to characterize their diversity has also several implications for solenogaster systematics. As two fast evolving mitochondrial markers were used in its analyses, without counterbalancing conservative markers the phylogeny cannot reliably resolve deep relationships within a group that has been hypothesized to date back to the early Paleozoic. Nevertheless, as our dataset contains multiple species and genera across several families, we were able to test the validity of existing taxonomic units: several classificatory entities (i.e. the largest order Cavibelonia, families Acanthomeniidae and Pruvotinidae) were retrieved as polyphyletic which will thus necessitate major systematic revisions in the future. The integrative approach developed during my dissertation allows for fast and efficient species delineation. Scleritome characters were chosen as the main morphological trait, as they are comparatively easy to access and provide the necessary link to the existing classificatory system to prevent a parallel system of DNA-based taxonomy. At the same time, reducing the amount of required characters presents an efficient solution when confronted with small-sized animals and high proportions of singletons that hamper the use of single individuals for multiple lines of investigation (e.g. morphology, anatomy, DNA). The set-up of our community-curated online database AplacBase currently serves as an openly accessible repository and initial identification tool, providing supporting information and guiding researchers through the essence of aplacophoran taxonomy. However, in order to overcome the taxonomic deficits prevalent in Solenogastres, novel approaches need to aim beyond the characterization of their diversity and consequently provide efficient solutions to the currently complicated process of species descriptions and diagnosis. Based on a backbone phylogeny stabilized by mitochondrial genomes, a streamlined approach combining “deep taxonomy” with rapid, DNA-based taxonomy is proposed to tackle the emerging wealth of novel Solenogastres species

Impacts of Unplugged Activities in Computer Science

Computer Science is a fast-growing subject amongst schools. Inside of the program, Computer Science, programming or coding is generally taught. Students will typically learn to code by first using a computer and following instructions. The purpose of this literature review is to research different ideas about unplugged activities used while teaching coding in Computer Science. Unplugged activities are projects that are conducted in hands-on activities instructing students how to code before using a computer. The question that this paper is looking to answer is “What impacts do unplugged activities have on students learning to code?” The research conducted will give examples of different types of projects completed as well as data supporting theories

RAP1-GTPase signaling and platelet function

Platelets are critical for hemostasis, i.e. the body's ability to prevent blood loss at sites of vascular injury. They patrol the vasculature in a quiescent, non-adhesive state for approximately 10 days, after which they are removed from circulation by phagocytic cells of the reticulo-endothelial system. At sites of vascular injury, they promptly shift to an activated, adhesive state required for the formation of a hemostatic plug. The small GTPase RAP1 is a critical regulator of platelet adhesiveness. Our recent studies demonstrate that the antagonistic balance between the RAP1 regulators, CalDAG-GEFI and RASA3, is critical for the modulation of platelet adhesiveness, both in circulation and at sites of vascular injury. The RAP1 activator CalDAG-GEFI responds to small changes in the cytoplasmic calcium concentration and thus provides sensitivity and speed to the activation response, essential for efficient platelet adhesion under conditions of hemodynamic shear stress. The RAP1 inhibitor RASA3 ensures that circulating platelets remain quiescent by restraining CalDAG-GEFI-dependent RAP1 activation. Upon cellular stimulation, it is turned off by P2Y12 signaling to enable sustained RAP1 activation, required for the formation of a stable hemostatic plug. This review will summarize important studies that elucidated the signaling pathways that control RAP1 activation in platelets

The Annual Meeting of the AFSV 2008 in Turkey

In 2008 the AFSV will hold its annual meeting in Turkey. In this contribution we provide information concerning the objectives of the meeting and the excursion programme

The seroprevalence and salivary shedding of herpesviruses in Behcet's syndrome and recurrent aphthous stomatitis

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