A CEP104-CSPP1 Complex Is Required for Formation of Primary Cilia Competent in Hedgehog Signaling

CEP104 is an evolutionarily conserved centrosomal and ciliary tip protein. CEP104 loss-of-function mutations are reported in patients with Joubert syndrome, but their function in the etiology of ciliopathies is poorly understood. Here, we show that cep104 silencing in zebrafish causes cilia-related manifestations: shortened cilia in Kupffer's vesicle, heart laterality, and cranial nerve development defects. We show that another Joubert syndrome-associated cilia tip protein, CSPP1, interacts with CEP104 at microtubules for the regulation of axoneme length. We demonstrate in human telomerase reverse transcriptase-immortalized retinal pigmented epithelium (hTERT-RPE1) cells that ciliary translocation of Smoothened in response to Hedgehog pathway stimulation is both CEP104 and CSPP1 dependent. However, CEP104 is not required for the ciliary recruitment of CSPP1, indicating that an intra-ciliary CEP104-CSPP1 complex controls axoneme length and Hedgehog signaling competence. Our in vivo and in vitro analyses of CEP104 define its interaction with CSPP1 as a requirement for the formation of Hedgehog signaling-competent cilia, defects that underlie Joubert syndrome

Preparative History vs Driving Force in Water Oxidation Catalysis: Parameter Space Studies of Cobalt Spinels

The development of efficient, stable, and economic water oxidation catalysts (WOCs) is a forefront topic of sustainable energy research. We newly present a comprehensive three-step approach to systematically investigate challenging relationships among preparative history, properties, and performance in heterogeneous WOCs. To this end, we studied (1) the influence of the preparative method on the material properties and (2) their correlation with the performance as (3) a function of the catalytic test method. Spinel-type Co3O4 was selected as a clear-cut model WOC and synthesized via nine different preparative routes. In search of the key material properties for high catalytic performance, these cobalt oxide samples were characterized with a wide range of analytical methods, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Raman spectroscopy, BET surface area analysis, and transmission electron microscopy. Next, the corresponding catalytic water oxidation activities were assessed with the three most widely applied protocols to date, namely, photocatalytic, electrocatalytic, and chemical oxidation. The activity of the Co3O4 samples was found to clearly depend on the applied test method. Increasing surface area and disorder as well as a decrease in oxidation states arising from low synthesis temperatures were identified as key parameters for high chemical oxidation activity. Surprisingly, no obvious property–performance correlations were found for photocatalytic water oxidation. In sharp contrast, all samples showed similar activity in electrochemical water oxidation. The substantial performance differences between the applied protocols demonstrate that control and comprehensive understanding of the preparative history are crucial for establishing reliable structure–performance relationships in WOC design

Microwave-Hydrothermal Tuning of Spinel-Type Co3O4 Water Oxidation Catalysts

Water oxidation is the bottleneck reaction for overall water splitting as a direct and promising strategy toward clean fuels. However, the development of robust and affordable heterogeneous water oxidation catalysts remains challenging, especially with respect to the wide parameter space of synthesis and resulting material properties. Oxide catalysts performance in particular has been shown to depend on both synthetic routes and applied catalytic test methods. We here focus on spinel-type Co3O4 as a representative case for an in-depth study of the influence of rather subtle synthetic parameter variations on the catalytic performance. To this end, a series of Co3O4 samples was prepared via time-saving and tunable microwave-hydrothermal synthesis, while systematically varying a single parameter at a time. The resulting spinel-type catalysts were characterized with respect to key materials properties, including crystallinity, oxidation state and surface area using a wide range of analytical methods, such as PXRD, Raman/IR, XAS and XPS spectroscopy. Their water oxidation activity in electrocatalytic and chemical oxidation setups was then compared and correlated with the obtained catalyst properties. Both water oxidation methods displayed related trends concerning favorable synthetic parameters, namely higher activity for lower synthesis temperatures, lower precursor concentrations, addition of hydrogen peroxide and shorter ramping and reaction times, respectively. In addition to the surface area, structural features such as disorder were found to be influential for the water oxidation activity. The results prove that synthetic parameter screening is essential for optimal catalytic performance, given the complexity of the underlying performance-properties relationships

Characterization of a Novel Human Endogenous Retrovirus, HERV-H/F, Expressed in Human Leukemia Cell Lines

AbstractWe have identified and characterized a human endogenous retrovirus (HERV) gag transcript in the human pre-B cell leukemia line Reh. The transcript was found to be a splice product of a structurally intact HERV element located on chromosome 6q13. Its primer binding site is complementary to phenylalanine (F) tRNA, common for the HERV-F family, but the overall genome sequence is closely related to the HERV-H family. The retroviral sequence was therefore designated HERV-H/F. The HERV element shows a distinct mRNA expression pattern among hematopoietic cancer cell lines with expression in some leukemia-derived cell lines of B-lymphoid and myeloid origin. No expression was observed in normal human tissues, indicating a cancer-specific expression pattern. The 5′ long terminal repeat (LTR) was tested for promoter activity in HERV-H/F expressing and nonexpressing cell lines. The cell specificity of the LTR-mediated reporter gene expression did not conclusively correlate with endogenous virus expression, indicating that the transcription regulation of this gene is not alone dependent on cell-specific activity of transcription factors

Isothermal relaxation kinetics for the reduction and oxidation of SrFeO3 based perovskites

The perovskite oxide SrFeO3 has favourable redox properties for oxygen exchange applications, including oxygen separation and oxygen production chemical looping cycles. For such applications, lower temperature operation can improve the energy demand and feasibility of the process, but can also lead to kinetic limitations. Here we investigate the oxidation and reduction reaction kinetics of SrFeO3 in the temperature range 450–750 K. Isothermal relaxation techniques are used to observe the reaction rates across this temperature range, using a thermogravimetric analysis system. Experimental data are analysed according to an isoconversional method and fit with a simple power law model to extract activation energies. The apparent activation energy of oxidation and reduction was found to be 92 ± 16 and 144 ± 17 kJ mol−1 respectively. Comparison of oxidation and reduction kinetics together with considerations of particle size indicate that the oxidation reaction rate may be limited by diffusion in the bulk, while the reduction reaction rate is limited by the surface reaction. Furthermore, we also investigated the mixed perovskite Sr0.93Ca0.07Fe0.9Co0.1O3, which exhibited a 4-fold increase in the oxidation rate

New distinct compartments in the G2 phase of the cell cycle defined by the levels of γH2AX.

Induction of DNA double strand breaks leads to phosphorylation and focus-formation of H2AX. However, foci of phosphorylated H2AX (γH2AX) appear during DNA replication also in the absence of exogenously applied injury. We measured the amount and the number of foci of γH2AX in different phases of the cell cycle by flow cytometry, sorting and microscopy in 4 malignant B-lymphocyte cell lines. There were no detectable γH2AX and no γH2AX-foci in G1 cells in exponentially growing cells and cells treated with PARP inhibitor (PARPi) for 24 h to create damage and reduce DNA repair. The amount of γH2AX increased immediately upon S phase entry, and about 10 and 30 γH2AX foci were found in mid-S phase control and PARPi-treated cells, respectively. The γH2AX-labeled damage caused by DNA replication was not fully repaired before entry into G2. Intriguingly, G2 cells populated a continuous distribution of γH2AX levels, from cells with a high content of γH2AX and the same number of foci as S phase cells (termed “G2H” compartment), to cells that there were almost negative and had about 2 foci (termed “G2L” compartment). EdU-labeling of S phase cells revealed that G2H was directly populated from S phase, while G2L was populated from G2H, but in control cells also directly from S phase. The length of G2H in particular increased after PARPi treatment, compatible with longer DNA-repair times. Our results show that cells repair replication-induced damage in G2H, and enter mitosis after a 2–3 h delay in G2L

3D-Structured Illumination Microscopy of Centrosomes in Human Cell Lines

The centrosome is the main microtubule-organizing center of animal cells, and is composed of two barrel-shaped microtubule-based centrioles embedded in protein dense pericentriolar material. Compositional and architectural re-organization of the centrosome drives its duplication, and enables its microtubule-organizing activity and capability to form the primary cilium, which extends from the mature (mother) centriole, as the cell exits the cell cycle. Centrosomes and primary cilia are essential to human health, signified by the causal role of centrosome- and cilia-aberrations in numerous congenic disorders, as well as in the etiology and progression of cancer. The list of disease-associated centrosomal proteins and their proximitomes is steadily expanding, emphasizing the need for high resolution mapping of such proteins to specific substructures of the organelle. Here, we provide a detailed 3D-structured illumination microscopy (3D-SIM) protocol for comparative localization analysis of fluorescently labeled proteins at the centrosome in fixed human cell lines, at approximately 120 nm lateral and 300 nm axial resolution. The procedure was optimized to work with primary antibodies previously known to depend on more disruptive fixation reagents, yet largely preserves centriole and centrosome architecture, as shown by transposing acquired images of landmark proteins on previously published transmission electron microscopy (TEM) images of centrosomes. Even more advantageously, it is compatible with fluorescent protein tags. Finally, we introduce an internal reference to ensure correct 3D channel alignment. This protocol hence enables flexible, swift, and information-rich localization and interdependence analyses of centrosomal proteins, as well as their disorder-associated mutations

A vállalkozások számára igénybe vehető hitelek a Raiffeisen Banknál

The room-temperature formation of bismuth oxycarbonate (Bi2O2CO3) from Bi2O3 in sodium carbonate buffer was investigated with in situ powder X-ray diffraction (PXRD) in combination with electron microscopy and vibrational spectroscopy. Time-resolved PXRD measurements indicate a pronounced and rather complex pH dependence of the reaction mechanism. Bi2O2CO3 formation proceeds within a narrow window between pH 8 and 10 via different mechanisms. Although a zero-dimensional nucleation model prevails around pH 8, higher pH values induce a change toward a diffusion-controlled model, followed by a transition to regular nucleation kinetics. Ex situ synthetic and spectroscopic studies confirm these trends and demonstrate that in situ monitoring affords vital parameter information for the controlled fabrication of Bi2O2CO3 materials. Furthermore, the β → α bismuth oxide transformation temperatures of Bi2O2CO3 precursors obtained from different synthetic routes differ notably (by min 50 °C) from commercially available bismuth oxide. Parameter studies suggest a stabilizing role of surface carbonate ions in the as-synthesized bismuth oxide sources. Our results reveal the crucial role of multiple preparative history parameters, especially of pH value and source materials, for the controlled access to bismuth oxide-based catalysts and related functional compounds

Isothermal relaxation kinetics for the reduction and oxidation of SrFeO3 based perovskites

The perovskite oxide SrFeO3 has favourable redox properties for oxygen exchange applications, including oxygen separation and oxygen production chemical looping cycles. For such applications, lower temperature operation can improve the energy demand and feasibility of the process, but can also lead to kinetic limitations. Here we investigate the oxidation and reduction reaction kinetics of SrFeO3 in the temperature range 450–750 K. Isothermal relaxation techniques are used to observe the reaction rates across this temperature range, using a thermogravimetric analysis system. Experimental data are analysed according to an isoconversional method and fit with a simple power law model to extract activation energies. The apparent activation energy of oxidation and reduction was found to be 92 ± 16 and 144 ± 17 kJ mol−1 respectively. Comparison of oxidation and reduction kinetics together with considerations of particle size indicate that the oxidation reaction rate may be limited by diffusion in the bulk, while the reduction reaction rate is limited by the surface reaction. Furthermore, we also investigated the mixed perovskite Sr0.93Ca0.07Fe0.9Co0.1O3, which exhibited a 4-fold increase in the oxidation rate