LSM14B controls oocyte mRNA storage and stability to ensure female fertility.

Controlled mRNA storage and stability is essential for oocyte meiosis and early embryonic development. However, how to regulate mRNA storage and stability in mammalian oogenesis remains elusive. Here we showed that LSM14B, a component of membraneless compartments including P-body-like granules and mitochondria-associated ribonucleoprotein domain (MARDO) in germ cell, is indispensable for female fertility. To reveal loss of LSM14B disrupted primordial follicle assembly and caused mRNA reduction in non-growing oocytes, which was concomitant with the impaired assembly of P-body-like granules. 10× Genomics single-cell RNA-sequencing and immunostaining were performed. Meanwhile, we conducted RNA-seq analysis of GV-stage oocytes and found that Lsm14b deficiency not only impaired the maternal mRNA accumulation but also disrupted the translation in fully grown oocytes, which was closely associated with dissolution of MARDO components. Moreover, Lsm14b-deficient oocytes reassembled a pronucleus containing decondensed chromatin after extrusion of the first polar body, through compromising the activation of maturation promoting factor, while the defects were restored via WEE1/2 inhibitor. Together, our findings reveal that Lsm14b plays a pivotal role in mammalian oogenesis by specifically controlling of oocyte mRNA storage and stability.

Transport of underdamped active particles in ratchet potentials.

We study the rectified transport of underdamped active noninteracting particles in an asymmetric periodic potential. It is found that the ratchet effect of active noninteracting particles occurs in a single direction (along the easy direction of the substrate asymmetry) in the overdamped limit. However, when the inertia is considered, it is possible to observe reversals of the ratchet effect, where the motion is along the hard direction of the substrate asymmetry. By changing the friction coefficient or the self-propulsion force, the average velocity can change its direction several times. Therefore, by suitably tailoring the parameters, underdamped active particles with different self-propulsion forces can move in different directions and can be separated.

Transport of alignment active particles in funnel structures.

We study the transport of alignment active particles in complex confined structures (an array of asymmetric funnels). It is found that due to the existence of the multiple pathways, the alignment interaction can enrich the transport behavior of active particles. In an array of asymmetric funnels, the purely nematic alignment always suppresses the rectification. However, the polar alignment does not always promote the rectification, the rectification is suppressed for large self-propulsion speed. In addition, we also found the existence of optimal parameters (the self-propulsion speed and the rotational diffusion coefficient) at which the directed velocity takes its maximal value.

The influence of a phase shift between the top and bottom walls on the Brownian transport of self-propelled particles.

Transport of noninteracting self-propelled particles is numerically investigated in a two-dimensional horizontally asymmetrical channel with nonstraight midline which can be controlled by the phase shift between the top and bottom walls. From numerical simulations, we found that self-propelled particles can be rectified by the self-propelled velocity. The direction of the average velocity is determined by the horizontally asymmetrical parameter of the channel. The average velocity is very sensitive to the phase shift and its behaviors can be manipulated by changing the phase shift. As the phase shift is increased, the average velocity decreases and its peak position moves (to right or left). Remarkably, the average velocity is zero when the phase shift is in the interval [ 3π/5, 4π/5]. The small phase shift may facilitate the rectification process for the large horizontal asymmetry of the channel.

Hydrodynamically enforced entropic Brownian pump.

Transport of overdamped Brownian particles in a finite hydrodynamical channel is investigated in the presence of the ac driving force and the pressure-driven flow. The system is bounded by two particle reservoirs. With the help of the Fick-Jacobs method, we obtain the directed current of Brownian particles and the pumping capacity of the system. The directed transport is determined by the competitions among the asymmetry of the channel, the ac driving force, the pressure-driven flow, and the concentration difference. Their interplays can exhibit the peculiar properties. Remarkably, the particles can be pumped through the channel from the lower concentration reservoir to the higher concentration one, or from the lower pressure side to the higher pressure one. In addition, due to the existence of the pressure drop, ac driving force still plays the significant role on directed transport even in a completely symmetric channel. Our results could be implemented in constrained structures with narrow channels or pores where the particles are suspended in a solvent.

Current control in a two-dimensional channel with nonstraight midline and varying width.

Transport of overdamped Brownian particles in a two-dimensional channel with nonstraight midline and narrow varying width is investigated in the presence of an asymmetric unbiased external force. In the adiabatic limit, we obtain the analytical expression of the directed current. It is found that the current is manipulated by changing the phase shift between the top and bottom walls of the channel. As the phase shift is increased from 0 to π, the variation of the channel width decreases and the current also decreases. Remarkably, the current is always zero when the phase shift is equal to π, where the entropic barrier disappears. In addition, the temporal asymmetric parameter of the unbiased force not only determines the direction of the current but also affects its amplitude.

Rectification and diffusion of self-propelled particles in a two-dimensional corrugated channel.

Rectification and diffusion of noninteracting self-propelled particles is numerically investigated in a two-dimensional corrugated channel. From numerical simulations, we obtain the average velocity and the effective diffusion coefficient. It is found that the self-propelled particles can be rectified by the self-propelled velocity. There exist optimal values of the parameters (the self-propelled velocity, the translational diffusion constant, and the height of the potential) at which the average velocity takes its maximal value. There exists an optimal translational diffusion at which the effective diffusion constant is maximal. The self-propelled velocity can strongly increase the effective diffusion, while the large rotational diffusion rate can strongly suppress the effective diffusion.

Curative effect analysis on improved medial parapatellar approach in the treatment of posterior medial tibial plateau fracture / 局解手术学杂志

Objective To discuss the clinical effects of improved medial parapatellar approach in the treatment of posterior medial tibial plateau fracture( PMF-TP) . Methods 60 patients with PMF-TP were selected from June 2014 to June 2017 in our hospital;according to the surgical methods,all patients were divided into improved group (30 cases) and medial group (30 cases);the medial group was treated with routine medial approach, while the improved group was treated with improved medial parapatellar approach. The operation, complications, fracture reduction and knee joint function were compared between the two groups. The amount of bleeding,the incidence of complications and the operation,hospitalization,weight bearing exercise and fracture healing time of improved group were significantly lower than those in the after the operation, the knee flexion and extensional activity of improved group was significantly higher than that in the medial group,the difference was statistically significant(P<0. 05). The fracture re-duction and knee joint function excellent rate 6 months after operation of improved group were significantly higher than those in the medial group,the difference was statistically significant(P<0. 05). Results Compared with the posteromedial approach of the knee joint, the im-proved medial parapatellar approach features simple and safe operation. It is beneficial to early functional exercise, fracture reduction and re-habilitation of knee joint function.