Near-future levels of ocean temperature weaken the byssus production and performance of the mussel Mytilus coruscus.

Marine mussels are key ecological engineers that form dense aggregations to maintain the vital habitat in benthic systems. It is essential to understand the consequences of mussel byssus attachment in elevated temperatures associated with ocean warming. We evaluated byssus production and the mechanical performance of threads in the mussel Mytilus coruscus at 21° (control), 27 °C (average temperature in the M. coruscus habitat during the summer season) and 31 °C (4 °C raised) for 72 h. We quantified byssus secretion and shedding number, measured byssal breaking force, byssal polyphenol oxidase (PPO) activity, byssal thread length and diameter. Expression of byssus foot protein genes was analyzed by quantitative real-time PCR in foot tissue. High seawater temperature decreased the number of newly secreted byssus and the diameter of byssal threads, leading to the reduction of byssal breaking force and the alteration of the weakest part of the thread. Increased breakpoints in the upper part of the thread (proximal region) were higher at 27 °C than at 21 °C. High-temperature stress significantly reduced the PPO activity in byssus at 31 °C in comparison to 21 °C. The expression of mussel foot protein genes was affected by elevated temperature. The increased gene expression of byssus collagen-like protein 2 (Mccol2) at 31 °C conflicted with the number of byssuses produced. Suggesting the reduction of mussel foot protein abundance is not the cause of decreased byssus production at 31 °C. These results show that byssus, as an extracellular structure of mussels, may be highly susceptible to the adverse effects of ocean warming.

RIP1/RIP3/MLKL mediates dopaminergic neuron necroptosis in a mouse model of Parkinson disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder and is characterized by severe neuronal loss. Necroptosis, or programmed cell necrosis, is mediated by the receptor interacting protein kinase-1 and -3/mixed lineage kinase domain-like protein (RIP1/RIP3/MLKL) pathway, and is involved in several neurodegenerative diseases. Here we aimed to explore the involvement of necroptosis in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP)-induced PD and determine the potential mechanisms. We found that the protein levels of RIP1, RIP3, and MLKL increased significantly in a MPTP-induced mouse PD model. High expression of RIP1/RIP3/MLKL was associated with severe loss of dopaminergic neurons. Pretreatment with necrostatin-1 or the knockout of the RIP3/MLKL gene to block necroptosis pathway dramatically ameliorated PD by increasing dopamine levels and rescuing the loss of dopaminergic neurons, independent of the apoptotic pathway. Moreover, upregulation of inflammatory cytokines in MPTP-treated mice was partially inhibited by deletion of RIP3 or MLKL gene, indicating that a positive feedback loop exists between these genes and inflammatory cytokines. Our data indicate that RIP1/RIP3/MLKL-mediated necroptosis is involved in the pathogenesis of MPTP-induced PD. Downregulating the expression of RIP1, RIP3, or MLKL can significantly attenuate MPTP-induced PD. Future therapy targeting necroptosis may be a promising new option.

Annexin A7 induction of neuronal apoptosis via effect on glutamate release in a rat model of subarachnoid hemorrhage.

OBJECTIVE: Glutamate excitotoxicity and neuronal apoptosis are suggested to contribute to early brain injury after subarachnoid hemorrhage (SAH). Annexin A7 (ANXA7) has been shown to regulate glutamate release. However, the role of ANXA7 in early brain injury after SAH has not been illustrated. In this study, we aimed to investigate the effect of ANXA7 knockdown in reducing the severity of early brain injury after SAH, and determine the underlying mechanisms. METHODS: Endovascular perforation was performed to induce SAH in male Sprague-Dawley rats. ANXA7-siRNA was administered via intraventricular injection 5 days before SAH induction. Neurological test, evaluation of SAH grade, assessment of blood-brain barrier (BBB) permeability, measurement of brain water content, Western blot, double immunofluorescence staining, TUNEL staining, and enzyme-linked immunosorbent assay (ELISA) were performed at 24 hours of SAH induction. RESULTS: ANXA7 protein expression increased significantly after SAH induction and was seen mainly in neurons. High expression of ANXA7 was associated with poor neurological status. ANXA7 knockdown dramatically ameliorated early brain injury through alleviating BBB disruption and brain edema. Further investigation of the mechanism showed that inhibiting ANXA7 expression can rescue neuronal apoptosis. In addition, ANXA7 knockdown also significantly reduced glutamate release, which was consistent with a significant increase of Bcl-2 expression and decreases of Bax and cleaved caspase-3 expression. CONCLUSIONS: ANXA7 can induce neuronal apoptosis by affecting glutamate release in rats with SAH. Downregulating the expression of ANXA7 can significantly attenuate early brain injury after SAH. Future therapy targeting ANXA7 may be a promising new choice.

A novel stereotaxic system for implanting a curved lead to two intracranial targets with high accuracy.

BACKGROUND: The multi-target deep brain stimulation (DBS) aimed at improving symptoms related to different nuclei is a promising research direction. However, to implant a single lead into multiple targets simultaneously is difficult with the current lead implantation method. NEW METHOD: We proposed a novel stereotaxic system used for implanting a curved lead to any two targets of the brain, and used the theoretical "curved lead method". First, a customized novel stereotaxic system was fabricated, and a solid cranial model with six fixed internal targets was made; second, CT scan was performed to locate the fixed internal targets; third, five curved leads were implanted to five selected pairs of targets, each following the calculated parameters of "curved lead pathway" with the novel stereotaxic system, respectively. Finally, CT scans were performed again to determine the exact locations of the curved leads. RESULTS: The five curved leads accurately passed through the five pairs of combined targets, respectively, and the average vector error of curved lead implantation was 0.70±0.24mm. COMPARISON WITH EXISTING METHOD(S): In most situations, performing a multiple-target DBS procedure with the current stereotaxic systems means increased number of implanted leads, increased incidence of operative complications, and increased medical costs. However, the novel stereotaxic system could guide a single lead to reach two selected targets of the brain with high accuracy. CONCLUSIONS: The novel stereotaxic system enables curved lead implantation with high accuracy, and can be considered as a useful complement to the current stereotaxic system.

Numerical simulation of the sedimentation of cylindrical pollutant particles in fluid.

The sedimentation of cylindrical pollutant particles which fall through a fluid is investigated. Differing from previous research work, particle oscillation and effect of particle on the fluid are considered, and the torque exerted on a particle when viscous fluid flow around a particle is got through experiment and included in the numerical simulation. The computational results showed that the sedimentation velocities of particle increase slowly with the increase of particle aspect ratio phi. For disk-like particle, when the motion direction of particle is parallel to axis of particle, particle falls more slowly than the case of perpendicular to axis of particle; while for rod-like particle, it is inverse. For sedimentation of a crowd of high-frequency oscillating cylindrical particles with arbitrary initial orientation, both vertical velocity and horizontal velocity oscillate dramatically, the degree of oscillation of the former is stronger than the later. A crowd of particles fall more quickly than an isolated particle. Particles tend to strongly align in the direction of gravity. The computational results agreed well with the experimental ones and helpful for controlling of pollutant particles.