Novel angucycline/angucyclinone family of natural products discovered between 2010 and 2020 / 生物工程学报

Angucyclines/angucyclinones are a large group of polycyclic aromatic polyketides and their producers are widely distributed in nature. This family of natural products attracts great attention because of their diverse biological activities and unique chemical structures. With the development of synthetic biology and the exploitation of the actinomycetes from previously unexplored environments, angucyclines/angucyclinones-like natural products with new skeletons were continuously discovered, thus enriching the structural diversity of this family. In this review we summarize the new angucyclines/angucyclinones analogues discovered in the last decade (2010-2020) by using different strategies, such as changing cultivation conditions, genetic modification, genome mining, bioactivity-guided compound isolation, and fermentation of actinomycetes from underexplored environments. We also discuss the role of synthetic biology in the discovery and development of new compounds of the angucycline/angucyclinone family.

Improvement of natural product production in Streptomyces by manipulating pathway-specific regulators / 生物工程学报

Streptomyces are major sources of bioactive natural products. Genome sequencing reveals that Streptomyces have great biosynthetic potential, with an average of 20-40 biosynthetic gene clusters each strain. However, most natural products from Streptomyces are produced in low yields under regular laboratory cultivation conditions, which hamper their further study and drug development. The production of natural products in Streptomyces is controlled by the intricate regulation mechanisms. Manipulation of the regulatory systems that govern secondary metabolite production will strongly facilitate the discovery and development of natural products of Streptomyces origin. In this review, we summarize progresses in pathway-specific regulators from Streptomyces in the last five years and highlight their role in improving the yields of corresponding natural products.

The safety and feasibility of a full-implanted cortical electrical stimulator with low-intensity stimulation in local cerebral infarction rats / 中国组织工程研究

BACKGROUND:Cortical electrical stimulation has achieved good effects in treatment of stroke through animal and clinical experiments. OBJECTIVE:To observe the effects of a ful y implanted cortical electrical stimulation device with long time, low intensity and various frequencies stimulation protocols on the neurological function recovery in a rat model of local cerebral infarction. METHODS:The cerebral infarction model was established through middle cerebral artery occlusion in 60 Sprague-Dawley adult male rats. Forty rats with 1-3 points by Bederson scale were detected with magnetic resonance imaging, which was used to confirm cortex infarction and to identify a location for implantation of stimulating electrode over the peri-infarct cortex. Twenty-three rats with cortex infarction were randomly divided into cortical electrical stimulation group (CES group, n=13) and no stimulation group (NS group;n=10). The device was implanted on 6 days after middle cerebral artery occlusion, and the stimulation was given for 16 days. The stimulation program consists of two sessions lasting half an hour each in the morning and in the afternoon respectively. Stimulator delivered biphasic charge balanced pulses (pulse width=200μs) with various frequencies of 50 Hz, 20 Hz and 5 Hz within 10 second blocks and then repeated. The rats of NS group were implanted with the device, but received no electrical stimulation. The behavioral tests, includingforelimb use asymmetry test and foot fault test were performed at 2 and 16 days after implantation. Final y, al of the devices were taken out to test if they were normal y working and al of the rats were sacrificed for hematoxylin-eosin staining, which can reflect the structure of peri-infarct cortex and cellmorphology. RESULTS AND CONCLUSION:There was only one stimulator in CES group cannot normal y work, and the remaining 22 ones worked wel . The skin covered the implanted stimulator was slightly ulcerated in one rat, and the incisions of the other rats were healed wel . Hematoxylin-eosin staining showed clear and intact structure in peri-infarction cortex (i.e., electrodes were implanted at the cortex), neurons arranged in neat rows, with abundant neuronal cytoplasm and clear nucleolus. The glial cells have complete structures, and there was no edema in the intercellular spaces. Foot-fault and forelimb use asymmetry tests showed the improved neurological function in rats of CES group than that of NS group. We designed a ful-implanted cortical electrical stimulator used in cerebral ischemic rats, and established an implanted method with long time, low intensity and various frequencies pulsed electrical stimulation. The results indicated the stimulation pattern in our study is safe and effective, and it can significantly promote functional recovery in local cerebral infarction rats.

Implanted cortical electrical stimulation and the expressions of Nissl bodies and growth-associated protein 43 In the brain after ischemic injury / 中华物理医学与康复杂志

Objective To investigate the effect of implanted cortical electrical stimulation (CES) on the expression of Nissl bodies and growth-associated protein 43 (GAP-43) in the brain after ischemic injury,and its mechanism.Methods Models of middle cerebral artery occlusion (MCAO) were established in 23 male Sprague-Dawley rats.They were randomly divided into a CES group (CES,n=13) and a no stimulation group (NS,n=10) and electrical stimulators were implanted in both groups.CES was applied for 14 d in the CES group but not in the NS group.The expression of Nissl bodies and GAP-43 around the infarct were quantified using version 6.0 of the ImagePro Plus system.Results In the CES group the Nissl bodies had a deep color,and their percentage of area was higher than that in the NS group.The GAP-43 positive expression area also had a relatively deep color,and the average percentage of positive expression area was also higher than that in the NS group.Conclusions CES can enhance the expression of Nissl bodies and GAP-43 after cerebral infarction.This suggests that CES can promote axon growth and the formation of new neural circuits.