Reich S., Schonfeld P., Wagener P., Letzel A., Ibrahimkutty S., Gokce B., Barcikowski S., Menzel A., dos Santos Rolo T., Plech A.

in Journal of Colloid and Interface Science, 489 (2017) 106-113. DOI:10.1016/j.jcis.2016.08.030

Abstract

© 2016 Elsevier Inc. Pulsed laser ablation in liquids (PLAL) is a multiscale process, involving multiple mutually interacting phenomena. In order to synthesize nanoparticles with well-defined properties it is important to understand the dynamics of the underlying structure evolution. We use visible-light stroboscopic imaging and X-ray radiography to investigate the dynamics occurring during PLAL of silver and gold on a macroscopic scale, whilst X-ray small angle scattering is utilized to deepen the understanding on particle genesis. By comparing our results with earlier reports we can elucidate the role of the cavitation bubble. We find that symmetry breaking at the liquid-solid interface is a critical factor for bubble motion and that the bubble motion acts on the particle distribution as confinement and retraction force to create secondary agglomerates.

Wulff N.C., Van De Kamp T., Dos Santos Rolo T., Baumbach T., Lehmann G.U.C.

in Scientific Reports, 7 (2017), 42345. DOI:10.1038/srep42345

Abstract

© The Author(s) 2017. Male genital organs are among the fastest evolving morphological structures. However, large parts of the male’s genitalia are often hidden inside the female during mating. In several bushcricket species, males bear a pair of sclerotized genital appendices called titillators. By employing synchrotron-based in vivo X-ray cineradiography on mating couples, we were able to visualize titillator movement and spermatophore attachment inside the female. Titillators are inserted and retracted rhythmically. During insertion the titillator processes tap the soft and sensillae-covered dorsal side of the female’s flap-like genital fold, which covers the opening of the female’s genitalia, without tissue penetration. Titillators thus appear to be initially used for stimulation; later they may apply pressure that forces the female’s genital fold to stay open, thereby aiding mechanically in spermatophore transfer.

Cecilia A., Baecker A., Hamann E., Rack A., van de Kamp T., Gruhl F.J., Hofmann R., Moosmann J., Hahn S., Kashef J., Bauer S., Farago T., Helfen L., Baumbach T.

in Materials Science and Engineering C, 71 (2017) 465-472. DOI:10.1016/j.msec.2016.10.038

Abstract

© 2016 Prostate cancer (PCa) currently is the second most diagnosed cancer in men and the second most cause of cancer death after lung cancer in Western societies. This sets the necessity of modelling prostatic disorders to optimize a therapy against them. The conventional approach to investigating prostatic diseases is based on two-dimensional (2D) cell culturing. This method, however, does not provide a three-dimensional (3D) environment, therefore impeding a satisfying simulation of the prostate gland in which the PCa cells proliferate. Cryogel scaffolds represent a valid alternative to 2D culturing systems for studying the normal and pathological behavior of the prostate cells thanks to their 3D pore architecture that reflects more closely the physiological environment in which PCa cells develop. In this work the 3D morphology of three potential scaffolds for PCa cell culturing was investigated by means of synchrotron X-ray computed micro tomography (SXCμT) fitting the according requirements of high spatial resolution, 3D imaging capability and low dose requirements very well. In combination with mechanical tests, the results allowed identifying an optimal cryogel architecture, meeting the needs for a well-suited scaffold to be used for 3D PCa cell culture applications. The selected cryogel was then used for culturing prostatic lymph node metastasis (LNCaP) cells and subsequently, the presence of multi-cellular tumor spheroids inside the matrix was demonstrated again by using SXCμT.

Koenig T., Zuber M., Trimborn B., Farago T., Meyer P., Kunka D., Albrecht F., Kreuer S., Volk T., Fiederle M., Baumbach T.

in Physics in Medicine and Biology, 61 (2016) 3427-3442, 3427. DOI:10.1088/0031-9155/61/9/3427

Abstract

© 2016 Institute of Physics and Engineering in Medicine. The x-ray dark-field contrast accessible via grating interferometry is sensitive to features at length scales well below what is resolvable by a detector system. It is commonly explained as arising from small-angle x-ray scattering (SAXS), and can be implemented both at synchrotron beamlines and with low-brilliance sources such as x-ray tubes. Here, we demonstrate that for tube based setups the underlying process of image formation can be fundamentally different. For focal spots or detector pixels that comprise multiple grating periods, we show that dark-field images contain a strong artificial and system-specific component not arising from SAXS. Based on experiments carried out with a nanofocus x-ray tube and the example of an excised rat lung, we demonstrate that the dark-field contrast observed for porous media transforms into a differential phase contrast for large geometric magnifications. Using a photon counting detector with an adjustable point spread function, we confirm that a dark-field image can indeed be formed by an intra-pixel differential phase contrast that cannot be resolved as such due to a dephasing between the periodicities of the absorption grating and the Talbot carpet. Our findings are further corroborated by a link between the strength of this pseudo-dark-field contrast and our x-ray tube’s focal spot size in a three-grating setup. These results must not be ignored when measurements are intended to be reproducible across systems.

Huang D.-Y., Bechly G., Nel P., Engel M.S., Prokop J., Azar D., Cai C.-Y., Van De Kamp T., Staniczek A.H., Garrouste R., Krogmann L., Dos Santos Rolo T., Baumbach T., Ohlhoff R., Shmakov A.S., Bourgoin T., Nel A.

in Scientific Reports, 6 (2016), 23004. DOI:10.1038/srep23004

Abstract

With nearly 100,000 species, the Acercaria (lice, plant lices, thrips, bugs) including number of economically important species is one of the most successful insect lineages. However, its phylogeny and evolution of mouthparts among other issues remain debatable. Here new methods of preparation permitted the comprehensive anatomical description of insect inclusions from mid-Cretaceous Burmese amber in astonishing detail. These “missing links” fossils, attributed to a new order Permopsocida, provide crucial evidence for reconstructing the phylogenetic relationships in the Acercaria, supporting its monophyly, and questioning the position of Psocodea as sister group of holometabolans in the most recent phylogenomic study. Permopsocida resolves as sister group of Thripida + Hemiptera and represents an evolutionary link documenting the transition from chewing to piercing mouthparts in relation to suction feeding. Identification of gut contents as angiosperm pollen documents an ecological role of Permopsocida as early pollen feeders with relatively unspecialized mouthparts. This group existed for 185 million years, but has never been diverse and was superseded by new pollenivorous pollinators during the Cretaceous co-evolution of insects and flowers. The key innovation of suction feeding with piercing mouthparts is identified as main event that triggered the huge post-Carboniferous radiation of hemipterans, and facilitated the spreading of pathogenic vectors.

Schwermann A.H., dos Santos Rolo T., Caterino M.S., Bechly G., Schmied H., Baumbach T., van de Kamp T.

in eLife, 5 (2016), e12129. DOI:10.7554/eLife.12129

Abstract

© Schwermann et al. External and internal morphological characters of extant and fossil organisms are crucial to establishing their systematic position, ecological role and evolutionary trends. The lack of internal characters and soft-tissue preservation in many arthropod fossils, however, impedes comprehensive phylogenetic analyses and species descriptions according to taxonomic standards for Recent organisms. We found well-preserved three-dimensional anatomy in mineralized arthropods from Paleogene fissure fillings and demonstrate the value of these fossils by utilizing digitally reconstructed anatomical structure of a hister beetle. The new anatomical data facilitate a refinement of the species diagnosis and allowed us to reject a previous hypothesis of close phylogenetic relationship to an extant congeneric species. Our findings suggest that mineralized fossils, even those of macroscopically poor preservation, constitute a rich but yet largely unexploited source of anatomical data for fossil arthropods.

Briceno R.D., Eberhard W.G., Chinea-Cano E., Wegrzynek D., Dos Santos Rolo T.

in Ethology Ecology and Evolution, 28 (2016) 53-76. DOI:10.1080/03949370.2014.1002114

Abstract

© 2015 Dipartimento di Biologia, Università di Firenze, Italia. A long-standing question in morphological evolution is why male genitalia tend to diverge more rapidly than other structures. One possible explanation is that male genitalia are under sexual selection to function as internal courtship devices. Males of closely related species may provide divergent stimulation using different genital morphologies and behaviors. Testing this hypothesis has been difficult, however, because the presumed genital courtship behavior is often hidden from view inside the female, and because studies of how the males genitalia interact with those of the female are nearly always limited to a single species in a given group, thus restricting opportunities for comparison of closely related species. We present new morphological and behavioral data for portions of the male genitalia that are hidden in the female during copulation in five species in the tsetse fly genus Glossina using data from dissections of pairs frozen in copula, artificially stimulated males, and from copulating pairs viewed with a new X-ray technique that allows events inside the female to be recorded in real time. These data almost certainly give only an incomplete view of this complex, previously hidden world. But even so they clearly reveal that, as predicted by sexual selection theory, the male genitalia of Glossina flies perform dramatic, stereotyped, rhythmic movements deep within the females reproductive tract and in inward folds of her external surface, and that many of these movements probably differ among closely related species. Most of the movements are not explicable as means by which the male anchors himself more securely to the female; all are likely to result in stimulation of the female. A female Glossina can be stimulated tactilely at a given moment during copulation at up to 8-10 or more different sites on her body.

Karpov D., Dos Santos Rolo T., Rich H., Kryuchkov Y., Kiefer B., Fohtung E.

in Proceedings of SPIE – The International Society for Optical Engineering, 9931 (2016), 99312F. DOI:10.1117/12.2235865

Abstract

© 2016 SPIE. Directional dependence of the index of refraction contains a wealth of information about anisotropic optical properties in semiconducting and insulating materials. Here we present a novel high-resolution lens-less technique that uses birefringence as a contrast mechanism to map the index of refraction and dielectric permittivity in optically anisotropic materials. We applied this approach successfully to a liquid crystal polymer film using polarized light from helium neon laser. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of emergent brilliant X-ray sources. Applications of this novel imaging technique are in disruptive technologies, including novel electronic devices, in which both charge and spin carry information as in multiferroic materials and photonic materials such as light modulators and optical storage.

Ibrahimkutty S., Wagener P., Rolo T.D.S., Karpov D., Menzel A., Baumbach T., Barcikowski S., Plech A.

in Scientific Reports, 5 (2015), 16313. DOI:10.1038/srep16313

Abstract

Pulsed-laser assisted nanoparticle synthesis in liquids (PLAL) is a versatile tool for nanoparticle synthesis. However, fundamental aspects of structure formation during PLAL are presently poorly understood. We analyse the spatio-temporal kinetics during PLAL by means of fast X-ray radiography (XR) and scanning small-angle X-ray scattering (SAXS), which permits us to probe the process on length scales from nanometers to millimeters with microsecond temporal resolution. We find that the global structural evolution, such as the dynamics of the vapor bubble can be correlated to the locus and evolution of silver nanoparticles. The bubble plays an important role in particle formation, as it confines the primary particles and redeposits them to the substrate. Agglomeration takes place for the confined particles in the second bubble. Additionally, upon the collapse of the second bubble a jet of confined material is ejected perpendicularly to the surface. We hypothesize that these kinetics influence the final particle size distribution and determine the quality of the resulting colloids, such as polydispersity and modality through the interplay between particle cloud compression and particle release into the liquid.

Greven H., Van De Kamp T., Dos Santos Rolo T., Baumbach T., Clemen G.

in Vertebrate Zoology, 65 (2015) 81-99.

Abstract

A study on the cranial morphology, especially on the tooth bearing (dental) systems of several preserved developmental stages (from early premetamorphic larvae, in which most skull elements were already present and ossified or ossified in part, to transformed adult) of the smooth newt Lissotriton vulgaris (Salamandridae) was undertaken. We used μCT (to visualize the ossified elements in general and their relationships to each other) and an overall Alizarinred staining (to at best visualize teeth, replacement teeth, tooth buds and, after removing the oral mucosa, the course of dental laminae). Specimens cleared and stained with Alzarinred and Alcianblue were shown to be less suitable for our questions. In one case we used histological sections to follow the course of dental laminae, and in a second case scanning electron microscopy to show the structure of teeth in detail. The general sequence, growth, and changes of the bony elements including the “dental systems”, especially around metamorphosis, known from several other salamandrids are largely confirmed. Concerning the “tooth systems”, metamorphic events include the late appearance of the maxillae, resorption of the coronoids and palatines including their tooth-patches, remodelling of the vomer, i.e. resorption of the vomerine larval tooth-patch, formation of the edentate vomerine plate, and outgrowth of the monstichously dentate vomerine bar (typical for salamandrids). We show evidence that the larval vomer is not completey resorbed and that, unlike what has been described for Salamandra salamandra, the development of the vomerine bar is probably preceded by a shift of the dental lamina towards the middle of the palate, leaving a broad area between larval vomer and dental lamina. We hypothesize that the connective tissue in this area ossifies later and extends posteriorly forming the vomerine bar. It is noteworthy that in nearly all larvae vomer and intact pterygopalatinum were very close together either on one side or on both sides leading in overwintered larvae to the fusion of the vomer and the palatinal portion of the pterygopalatinum, primarily on one side. The zone of fusion is always characterized by a buccal notch. We think that in L. vulgaris the formation of “vomeropterygopalatina” is supported by the close proximity of the two bones and that these bones may fuse due to an imbalance between differentiation- and growth rate (indirectly caused by low temperatures). Approximation and especially fusion of the two bones correspond with the extension of the vomerine dental lamina into the area of the palatine, which temporally provides the latter with teeth. Overwintered larvae show further deviations concerning growth and differentiation of the mouth roof, which can be also interpreted as signs of delayed metamorphosis. They retain, for example, a largely intact dentate palatine, but with some regression of its tooth-patch, while the larval vomer is enlarged anteriorly and posteriorly and its number of teeth has increased; and the largely intact pterygopalatinal bony bridge. Further, maxillae begin to ossify. All larvae obviously have reached a late premetamorphic larval stage before the delay has started.