The continuously forming fin bony rays of zebrafish represent a simple bone model system in which mineralization is temporally and spatially resolved. The mineralized collagen fibrils of the fin bones are identical in structure to those found in all known bone materials. We study the continuous mineralization process within the tissue by using synchrotron microbeam x-ray diffraction and small-angle scattering, combined with cryo-scanning electron microscopy. The former provides information on the mineral phase and the mineral particles size and shape, whereas the latter allows high-resolution imaging of native hydrated tissues. The integration of the two techniques demonstrates that new mineral is delivered and deposited as packages of amorphous calcium phosphate nanospheres, which transform into platelets of crystalline apatite within the collagen matrix.one mineral formation has been extensively investigated both at the cellular level and at the level of the mineral and the macromolecules. Key questions, as yet unanswered, are how mineral is delivered to the crystallization site and whether this first-formed mineral is the same as in mature bone. The possibility that calcium phosphate precursor phases are delivered and first deposited in bone has been debated for decades (1-3). In vitro precipitation of calcium phosphates from solution often progresses through the deposition of amorphous calcium phosphate (ACP) as the first-formed mineral phase (4). ACP transforms into octacalcium phosphate (OCP), which then undergoes hydrolysis to form carbonated hydroxyapatite (HAP), the mineral phase of mature bone (4). Crane et al. (5) used Raman microspectroscopy to show that in the forming cranial suture of a mouse, an OCPlike phase was deposited prior to the formation of the mature mineral. Mahamid et al. (6) showed that in the continuously forming fin rays of a zebrafish, the newly formed bone contains large amounts of ACP. Beniash et al. (7) reported the presence of ACP in the forming enamel of mouse incisors. Interestingly, recent experiments successfully reproducing oriented intrafibrillar collagen mineralization in vitro utilized anionic polypeptides (polyaspartate) for transient stabilization of amorphous mineral as a precursor for the mature HAP crystallites (3, 8). All the above studies are consistent with ACP being a precursor phase in bone formation, but direct observation of the process in situ is still absent.The transient precursor phase strategy has been adopted by many invertebrate mineralizing groups (reviewed in ref. 9). Many of these taxa first deposit amorphous calcium carbonate, which subsequently transforms into crystalline calcite or aragonite.

X-ray scattering experiments at synchrotron sources are characterized by large and constantly increasing amounts of data. The great number of files generated during a synchrotron experiment is often a limiting factor in the analysis of the data, since appropriate software is rarely available to perform fast and tailored data processing. Furthermore, it is often necessary to perform online data reduction and analysis during the experiment in order to interactively optimize experimental design. This article presents an open-source software package developed to process large amounts of data from synchrotron scattering experiments. These data reduction processes involve calibration and correction of raw data, one-or two-dimensional integration, as well as fitting and further analysis of the data, including the extraction of certain parameters. The software, DPDAK (directly programmable data analysis kit), is based on a plug-in structure and allows individual extension in accordance with the requirements of the user. The article demonstrates the use of DPDAK for on-and offline analysis of scanning small-angle X-ray scattering (SAXS) data on biological samples and microfluidic systems, as well as for a comprehensive analysis of grazing-incidence SAXS data. In addition to a comparison with existing software packages, the structure of DPDAK and the possibilities and limitations are discussed.

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Spiders mainly feed on insects. This means that their fangs, which are used to inject venom into the prey, have to puncture the insect cuticle that is essentially made of the same material, a chitin‐protein composite, as the fangs themselves. Here a series of structural modifications in the fangs of the wandering spider Cupiennius salei are reported, including texture variation in chitin orientation and arrangement, gradients in protein composition, and selective incorporation of metal ions (Zn and Ca) and halogens (Cl). These modifications influence the mechanical properties of the fang in a graded manner from tip to base, allowing it to perform as a multi‐use injection needle that can break through insect cuticle, which is made of a chitin composite as well.

A new instrument for simultaneous microbeam small-and wide-angle X-ray scattering and X-ray fluorescence (SAXS/WAXS/XRF) is presented. The instrument is installed at the microfocus beamline at BESSY II and provides a beam of 10 mm size with a flux of about 10 9 photons s À1. A SAXS resolution up to 500 Å d-spacing and a range of scattering vectors of almost three orders of magnitude are reached by using a large-area high-resolution CCD-based detector for simultaneous SAXS/WAXS. The instrument is particularly suited for scanning SAXS/WAXS/XRF experiments on hierarchically structured biological tissues. The necessary infrastructure, such as a cryo-stream facility and an on-site preparation laboratory for biological specimens, are available.