Construction of EF-G knockdown strain of Mycobacterium smegmatis and drug resistance analysis / 生物工程学报

As the only translational factor that plays a critical role in two translational processes (elongation and ribosome regeneration), GTPase elongation factor G (EF-G) is a potential target for antimicrobial agents. Both Mycobacterium smegmatis and Mycobacterium tuberculosis have two EF-G homologous coding genes, MsmEFG1 (MSMEG_1400) and MsmEFG2 (MSMEG_6535), fusA1 (Rv0684) and fusA2 (Rv0120c), respectively. MsmEFG1 (MSMEG_1400) and fusA1 (Rv0684) were identified as essential genes for bacterial growth by gene mutation library and bioinformatic analysis. To investigate the biological function and characteristics of EF-G in mycobacterium, two induced EF-G knockdown strains (Msm-ΔEFG1(KD) and Msm-ΔEFG2(KD)) from Mycobacterium smegmatis were constructed by clustered regularly interspaced short palindromic repeats interference (CRISPRi) technique. EF-G2 knockdown had no effect on bacterial growth, while EF-G1 knockdown significantly retarded the growth of mycobacterium, weakened the film-forming ability, changed the colony morphology, and increased the length of mycobacterium. It was speculated that EF-G might be involved in the division of bacteria. Minimal inhibitory concentration assay showed that inhibition of EF-G1 expression enhanced the sensitivity of mycobacterium to rifampicin, isoniazid, erythromycin, fucidic acid, capreomycin and other antibacterial agents, suggesting that EF-G1 might be a potential target for screening anti-tuberculosis drugs in the future.

Advanced understanding in mechanisms of epilepsy and potential new treatment strategies

Over the last 25 years, neurobiologists have begun to unravel the cellular mechanisms that underlie epileptiform activity. Such investigations have two main objectives: [1] to develop new methods for treating, [curing], or preventing epilepsy; and [2] to learn more about the normal functioning of the human brain, at the cellular/molecular and neurological/psychological levels by analyzing abnormal brain functioning. The electroencephalogram [EF.G] spike is a marker for the hyperexcitable cortex and arises in or near an area with a high epileptogenic potential. The depolarizing shift [DS] that underlies the interictal discharge [ID] appears to be generated by a combination of excitatory synaptic currents and intrinsic voltage-dependent membrane currents. The hyperpolarization that follows the DS [post-DS-1 IT] hunts ID duration, determines ID frequency, and prevents ID deterioration into seizures. The disappearance of the post-DS I IP in some models is related to the onset of seizures and the spread of epileptiform activity. During the transition to seizures, the usually self-limited ID spreads in time and anatomical space. Several processes may intervene in the pathophysiolpgical dysfunction. These include enhancing GABA-mediated inhibition, dampening NMDA-mediated excitability, interfering with specific Ca[2+] currents in central neurons, and perhaps stimulating [gating] pathways