Noise exposure can cause structural and functional problem in the auditory cortex (AC) and hippocampus, the two brain regions in the auditory and non-auditory systems respectively. The aim of the present study was to explore which one of these two brain regions may be more susceptible to environmental noise. The AC and hippocampus of mice were separated following 1 or 3 weeks exposure to moderate noise (80 dB SPL, 2 h/day). The levels of oxidative stress and tau phosphorylation were then measured to evaluate the effects by noise. Results showed significant peroxidation and tau hyperphosphorylation in the hippocampus with 1 week of noise exposure. However, the AC did not show significant changes until exposure for 3 weeks. These data suggest that although the hippocampus and AC were affected by moderate noise exposure, the hippocampus in the non-auditory system may have been more vulnerable to environmental noise than the AC.
Dysfunction of proteasome contributes to the accumulation of the abnormally hyperphosphorylated tau in Alzheimer's disease. However, whether tau hyperphosphorylation and accumulation affect the activity of proteasome is elusive. Here we found that a moderate tau phosphorylation activated the trypsin-like activity of proteasome, whereas further phosphorylation of tau inhibited the activity of the protease in HEK293 cells stably expressing tau441. Furthermore, tau hyperphosphorylation could partially reverse lactacystin-induced inhibition of proteasome. These results suggest that phosphorylation of tau plays a dual role in modulating the activity of proteasome.
Zero
valent iron (ZVI) is recently regarded as a promising alternative
for water disinfection, but still suffers from low efficiency. Herein
we demonstrate that amorphous zerovalent iron microspheres (A-mZVI)
exhibit both higher inactivation rate and physical removal efficiency
for the disinfection of Escherichia coli than conventional
crystalline nanoscale ZVI (C-nZVI) under aerobic condition. The enhanced E. coli inactivation performance of A-mZVI was mainly attributed
to more reactive oxygen species (ROSs), especially free •OH,
generated by the accelerated iron dissolution and molecular oxygen
activation in bulk solution. In contrast, C-nZVI preferred to produce
surface bound •OH, and its bactericidal ability was thus hampered
by the limited physical contact between C-nZVI and E. coli. More importantly, hydrolysis of dissolved iron released from A-mZVI
produced plenty of loose FeOOH to wrap E. coli, increasing
the dysfunction of E. coli membrane. Meanwhile, this
hydrolysis process lowered the stability of E. coli colloid and caused its rapid coagulation and sedimentation, favoring
its physical removal. These findings clarify the indispensable roles
of ROSs and iron corrosion products during the ZVI disinfection, and
also provide a promising disinfection material for water treatment.
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