RhoA-mediated FMNL1 regulates GM130 for actin assembly and phosphorylates MAPK for spindle formation in mouse oocyte meiosis

<p>Formin-like 1 (FMNL1) is a member of Formin family proteins which are the actin nucleators. Although FMNL1 activities have been shown to be essential for cell adhesion, cytokinesis, cell polarization and migration in mitosis, the functional roles of mammalian FMNL1 during oocyte meiosis remain uncertain. In this study, we investigated the functions of FMNL1 in mouse oocytes using specific morpholino (MO) microinjection and live cell imaging. Immunofluorescent staining showed that in addition to its cytoplasmic distribution, FMNL1 was primarily localized at the spindle poles after germinal vesicle breakdown (GVBD). FMNL1 knockdown caused the low rate of polar body extrusion and resulted in large polar bodies. Time-lapse microscopic and immunofluorescence intensity analysis indicated that this might be due to the aberrant actin expression levels. Cortical polarity was disrupted as shown by a loss of actin cap and cortical granule free domain (CGFD) formation, which was confirmed by a failure of meiotic spindle positioning. And this might be the reason for the large polar body formation. Spindle formation was also disrupted, which might be due to the abnormal localization of p-MAPK. These results indicated that FMNL1 affected both actin dynamics and spindle formation for the oocyte polar body extrusion. Moreover, FMNL1 depletion resulted in aberrant localization and expression patterns of a cis-Golgi marker protein, GM130. Finally, we found that the small GTPase RhoA might be the upstream regulator of FMNL1. Taken together, our data indicate that FMNL1 is required for spindle organization and actin assembly through a RhoA-FMNL1-GM130 pathway during mouse oocyte meiosis.</p

In Situ Growth of Free-Standing All Metal Oxide Asymmetric Supercapacitor

Metal oxides have attracted renewed interest in applications as energy storage and conversion devices. Here, a new design is reported to acquire an asymmetric supercapacitor assembled by all free-standing metal oxides. The positive electrode is made of 3D NiO open porous nanoribbons network on nickel foam and the negative electrode is composed of SnO₂/MnO₂ nanoflakes grown on carbon cloth (CC) substrate. The combination of two metal oxide electrodes which replaced the traditional group of carbon materials together with metal oxide has achieved a higher energy density. The self-supported 3D NiO nanoribbons network demonstrates a high specific capacitance and better cycle performance without obvious mechanical deformation despite of undergoing harsh bulk redox reactions. The SnO₂/MnO₂ nanoflakes as the pseudocapacitive electrode exhibit a wide range of voltage window (−1 to 1 V), which is conducive to electrochemical energy storage. The (CC/SnO₂/MnO₂)­(−)//(NiO/Ni foam)­(+) asymmetric supercapacitor device delivers an energy density of 64.4 Wh kg^–1 (at a power density of 250 W kg^–1) and two devices in series are applied to light up 24 red LEDs for about 60 s. The outstanding electrochemical properties of the device hold great promise for long-life, high-energy, and high-power energy storage/conversion applications

Robust and Conductive Na₂Ti₂O_5–<i>x</i> Nanowire Arrays for High-Performance Flexible Sodium-Ion Capacitor

Hybrid capacitors, especially sodium-ion capacitors (SICs), which combine the complementary merits of high-energy batteries and high-power capacitors, have received increasing research interest and have been expected to bridge the gap between the rechargeable batteries and EDLCs. The biggest challenge for SICs is to overcome the kinetics discrepancy between the sluggish faradaic anode and the rapid nonfaradaic capacitive cathode. To boost the Na⁺ reaction kinetics, robust and conductive Na₂Ti₂O_5–<i>x</i> nanowire arrays have been constructed as an accessible and affordable SIC anode. It is found that the utilization of oxygen vacancies (OVs) can endow Na₂Ti₂O_5–<i>x</i> high electrical conductivity, introduce intercalation pseudocapacitance, and maintain the crystal structure integrity. It exhibits high reversible discharge capacity (225 mAh g^–1 at 0.5C), superior rate capability, and ultralong lifespan when utilized as self-supported and additive-free anode for SIB, remaining almost 100% capacity retention after 20 000 cycles at 25 C. When assembled as flexible hybrid SIC (4.5 cm³) with rGO/AC film cathode, a high-level energy density of 70 Wh kg^–1 at power density of 240 W kg^–1 based on active materials can be achieved, and high volumetric energy density (15.6 Wh L^–1) and power density (120 W L^–1) based on the whole packge volume can be delivered with superior cycle stability (5000 cycles, 82.5%)

Clustered-Microcapsule-Shaped Microporous Carbon-Coated Sulfur Composite Synthesized via in Situ Oxidation

Hollow materials as sulfur hosts have been intensively investigated to address the poor cycling stabilities of Li–S batteries. Herein, we report an enhanced hollow framework to improve the applicability of the sulfur confinement. A clustered-microcapsule-shaped microporous carbon coated sulfur (CM-S@MPC) composite is prepared from the clustered zinc sulfide precursor, through an in situ oxidation process. The high specific surface area and the in situ preparation guarantee the uniform distribution of sulfur inside the carbon microcapsule, even under a higher sulfur content of 83 wt %. In addition, the interconnected frame constructed by the stacking of carbon microcapsules also mitigates the lithium polysulfide loss by setting interlayered hurdles on their pathway along the outward diffusion. Hence, these enable a full demonstration of excellent cycling stability, compared to the control sample obtained via physical sulfur infiltration. The outstanding decay rate of 0.039% per cycle is achieved during 700 cycles at 1 C, even under high sulfur loading

Effects of CK666 treatment and RNAi on actin cap formation in mouse oocytes.

<p>The chromosomes in the control group had moved to the cortex and an actin cap had formed by the late MI stage, whilst the chromosomes of the CK666 treatment and RNAi oocytes remained at a central position and no actin cap was observed. The chromosomes segregated at the cortex of the oocyte during TI in the control group. In oocytes treated with CK666 and RNAi, no actin cap formed, oocytes segregated with the chromosomes at the central position, and cytokinesis was initiated from this central location. During MII, a small polar body and a large oocyte formed in the control group, whilst CK666 treatment and RNAi samples formed two cell-like structures. An arrowhead illustrates the actin cap. Green, actin; blue, chromatin. Bar = 20 µm.</p

Arp2/3 complex was involved in multiple processes associated with oocyte polarization, including spindle migration and cytokinesis.

<p>Disruption of spindle migration caused the spindle to remain in a central position and symmetrical division to occur. Disruption of cytokinesis caused arrest during telophase I and a failure to extrude the polar body.</p

Effects of CK666 treatment and RNAi on cytokinesis in mouse oocytes.

<p>(<b>A</b>) In the control group, the oocytes extruded the polar body and arrested at the MII stage, whilst the arrest occurred during telophase I and the chromosomes condensed following treatment with CK666 and RNAi. Green, α-tubulin; blue, chromatin. Bar = 20 µm. (<b>B</b>) Frequency of telophase I arrested oocytes after 12 h in culture by RNAi. *, significantly different (p<0.05). (<b>C</b>) Time lapse microscopy of maturing oocytes treated with CK666. The oocytes failed to show the completion of cytokinesis after 16 h culture and remained at the TI stage.</p

3D Hierarchical Pt-Nitrogen-Doped-Graphene-Carbonized Commercially Available Sponge as a Superior Electrocatalyst for Low-Temperature Fuel Cells

Three-dimensional hierarchical nitrogen-doped graphene (3D-NG) frameworks were successfully fabricated through a feasible solution dip-coating method with commercially available sponges as the initial backbone. A spongy template can help hinder the graphene plates restacking in the period of the annealing process. The Pt/3D-NG catalyst was synthesized employing a polyol reduction process. The resultant Pt/3D-NG exhibits 2.3 times higher activity for methanol electro-oxidation along with the improvement in stability as compared with Pt/G owing to their favorable features including large specific surface area, high pore volume, high N doping level, and the homogeneous dispersion of Pt nanoparticles. Besides, Pt/3D-NG also presents high oxygen reduction reaction (ORR) performance in acid media when compared with Pt/3D-G and Pt/G. This work raises a valid solution for the fabrication of 3D functional freestanding graphene-based composites for a variety of applications in fuel cell catalysis, energy storage, and conversion

Effects of CK666 treatment and RNAi on cortical granule-free domain formation in mouse oocytes.

<p>The cortical granules were absent in the cortex close to where the chromosomes were located during the MI and MII stages in the control group. Conversely, in the oocytes treated with CK666 and RNAi, the cortical granules were distributed throughout the entire cortex. Z-stack showed the presence of different scanned layers. An arrowhead shows the cortical granule-free domain. Green, cortical granules; blue, chromatin. Bar = 20 µm.</p

Localization of Arp2/3 complex in mouse oocytes.

<p>(<b>A</b>) Subcellular localization of the Arp2/3 complex during mouse oocyte meiotic maturation. ARP2 antibody staining was employed to show the subcellular localization of the Arp2/3 complex in mouse oocytes as revealed by immunofluorescence staining. From the GV to the MII stage, all ARP2 accumulated at the cortex of the oocytes and the region near the cortex. Green, actin; red, ARP2; blue, chromatin. Bar = 20 µm. (<b>B</b>) Subcellular localization of the Arp2/3 complex after CB treatment during mouse oocyte meiotic maturation. The subcellular localization of ARP2 in mouse oocytes was revealed by immunofluorescence staining. Actin was disrupted during the MI stage and ARP2 dispersed into the cytoplasm. Green, actin; red, ARP2; blue, chromatin. Bar = 20 µm.</p