Biofouling control and sludge properties promotion through quorum quenching in membrane bioreactors at two aeration intensities

Objective

A modified method was used for cell entrapped beads (CEBs) preparation and two aeration intensities (low and high aeration intensity) was supplied as factors to investigate the change of quorum quenching performance for membrane biofouling in membrane bioreactor (MBR).

Results

Dehydrogenase activity and growth trend of activated sludge were improved at high aeration intensity. Compared with C-MBR (with vacant beads), QQ-MBR (with CEBs) had more stable quorum quenching activity and longer application time at high aeration intensity, in which the proteins and polysaccharides were reduced by 15 and 20%, respectively. The difference of EPS concentration in mixed liquor was attributed to the protein concentration controlled by quorum quenching bacteria, meanwhile sufficient organics was necessary to maintain the process.

Conclusions

The better settleability, greater stability and relatively lower hydrophobicity of activated sludge properties was achieved with quorum quenching. The scouring effect of CEBs was promoted at high aeration intensity, further controlling the membrane biofouling.

     

Virtual stenting workflow with vessel-specific initialization and adaptive expansion for neurovascular stents and flow diverters

Endovascular intervention using traditional neurovascular stents and densely braided flow diverters (FDs) have become the preferred treatment strategies for traditionally challenging intracranial aneurysms. Modeling stent and FD deployment in patient-specific aneurysms and its flow modification results prior to the actual intervention can potentially predict the patient outcome and treatment optimization. We present a clinically focused, streamlined virtual stenting workflow that efficiently simulates stent and FD treatment in patient-specific aneurysms based on expanding a simplex mesh structure. The simplex mesh is generated using an innovative vessel-specific initialization technique, which uses the patient’s parent artery diameter to identify the initial position of the simplex mesh inside the artery. A novel adaptive expansion algorithm enables the acceleration of deployment process by adjusting the expansion forces based on the distance of the simplex mesh from the parent vessel. The virtual stenting workflow was tested by modeling the treatment of two patient-specific aneurysms using the Enterprise stent and the Pipeline Embolization Device (commercial FD). Both devices were deployed in the aneurysm models in a few seconds. Computational fluid dynamics analyses of pre- and post-treatment aneurysmal hemodynamics show flow reduction in the aneurysmal sac in treated aneurysms, with the FD diverting more flow than the Enterprise stent. The test results show that this workflow can rapidly simulate clinical deployment of stents and FDs, hence paving the way for its future clinical implementation.     

Changes of characteristics of preoptic neurons and NA metabolism in hypothalamus of ground squirrel (Citelleus Dautieus) in different seasons and hibernating phases

Ｆｒｏｍｌａｔｅｆａｌｌｏｒｅａｒｌｙｗｉｎｔｅｒｏｎ,ｔｈｅｈｉｂｅｒｎａｔｏｒｂｅｇｉｎｓｓｅｖｅｒａｌｃｙｃｌｅｓ(ｈｉｂｅｒｎａｔｉｏｎｂｏｕｔｓ),ｅａｃｈｏｆｗｈｉｃｈｃｏｎｓｉｓｔｓｏｆｈｉｂｅｒｎａｔｉｏｎｅｎｔｒａｎｃｅ,ｄｅｅｐｈｉｂｅｒｎａｔｉｏｎａｎｄｔｒａｎｓｉｅｎｔａｒｏｕｓａｌｕｎｔｉｌｉｔｓｗａｋｉｎｇｉｎｓｐｒｉｎｇ.Ｔｈｅｂｏｄｙｔｅｍｐｅｒａｔｕｒｅｃｈａｎｇｅｏｆｔｈｅｈｉｂｅｒｎａｔｏｒｄｕｒｉｎｇｈｉｂｅｒｎａｔｉｏｎｈａｓｔｗｏｍａｊｏｒｆｅａｔｕｒｅｓ:…     

Drosophila Casein Kinase 2 (CK2) Promotes Warts Protein to Suppress Yorkie Protein Activity for Growth Control

Drosophila Hippo signaling regulates Wts activity to phosphorylate and inhibit Yki in order to control tissue growth. CK2 is widely expressed and involved in a variety of signaling pathways. In this study we report that Drosophila CK2 promotes Wts activity to phosphorylate and inhibit Yki activity, which is independent of Hpo-induced Wts promotion. In vivo, CK2 overexpression suppresses hpo mutant-induced expanded (Ex) up-regulation and overgrowth phenotype, whereas it cannot affect wts mutant. Consistent with this, knockdown of CK2 up-regulates Hpo pathway target expression. We also found that Drosophila CK2 is essential for tissue growth as a cell death inhibitor as knockdown of CK2 in the developing disc induces severe growth defects as well as caspase3 signals. Taken together, our results uncover a dual role of CK2; although its major role is promoting cell survive, it may potentially be a growth inhibitor as well.     

Development and utilization of a new chemically‐induced soybean library with a high mutation density

Mutagenized populations have provided important materials for introducing variation and identifying gene function in plants. In this study, an ethyl methanesulfonate (EMS)‐induced soybean (Glycine max) population, consisting of 21,600 independent M₂ lines, was developed. Over 1,000 M_{4 (5)} families, with diverse abnormal phenotypes for seed composition, seed shape, plant morphology and maturity that are stably expressed across different environments and generations were identified. Phenotypic analysis of the population led to the identification of a yellow pigmentation mutant, gyl, that displayed significantly decreased chlorophyll (Chl) content and abnormal chloroplast development. Sequence analysis showed that gyl is allelic to MinnGold, where a different single nucleotide polymorphism variation in the Mg‐chelatase subunit gene (ChlI1a) results in golden yellow leaves. A cleaved amplified polymorphic sequence marker was developed and may be applied to marker‐assisted selection for the golden yellow phenotype in soybean breeding. We show that the newly developed soybean EMS mutant population has potential for functional genomics research and genetic improvement in soybean.     

肠道菌群与病毒性肺炎关系的研究进展

在21世纪头20年里,呼吸道病毒造成的地区性乃至世界性的流行已经发生多次,而疫情的暴发严重威胁人类健康与生存,但临床上,仍缺乏针对病毒的特异性治疗手段。随着肠道微生态相关研究的广泛开展,肠道菌群在哮喘,纤维化及细菌性感染等多种肺部疾病的发病及防治中发挥着重要作用,成为"肠-肺轴"的关键枢纽。病毒性肺炎与肠道微生态间也存在着紧密的相互联系,通过改善肠道菌群,对呼吸病毒感染具有较好的防治作用。其内在机制主要涉及到:通过增强肠道黏膜屏障功能、减少继发性细菌的感染;通过菌体成分或者代谢产物如短链脂肪酸,色氨酸代谢产物等提高固有样淋巴细胞(Innate lymphoid cells,ILC)、单核-巨噬细胞、树突状细胞、自然杀伤细胞(Natural killer,NK)、粒细胞等固有免疫细胞的抗病毒免疫功能及调节Th17/Treg平衡抑制过度的炎症反应等。本文将系统回顾已发表的文章,对肠道菌群在病毒性肺炎方面的研究作系统的阐述,以求为研究者在病毒性肺炎的机制探究和防治方面提供帮助。     

Changes of characteristics of preoptic neurons and NA metabolism in hypothalamus of ground squirrel (Citelleus Dautieus) in different seasons and hibernating phases

The unit firing activities of neurons in the preoptic area (POA) of ground squirrel hypothalamic tissue slices were recorded and the metabolism of NA in hypothalamus was measured with high performance liquid chromatography (HPLC). Thermosensitivity, proportions, the critical temperature (Tc) and the lowest temperature (TL) of firing activity of the above-mentioned neurons, and NA metabolism in hypothalamus were compared in different seasons and hibernating phases. In comparison with that in summer euthermar, it was shown that (i) the percentage and thermosensitivity of the POA neurons varied respectively in the hibernating phases; (ii) TL and Tc of the POA neurons in winter, both euthermar and hibernation, were markedly decreased; (iii) the POA neurons in hibernation became much more sensitive to NA, and the response of cold-sensitive neurons to NA changed from inhibiting pattern in summer to exciting one in hibernation; (iv) the contents and metabolism of NA in hypothalamus decreased significantly in the entering phase and deep hibernation phase, while the metabolism of NA increased remarkably in the arousal phase. These changes might explain the regulatory mechanism how ground squirrel actively decreases body temperature (Tb) in entering into hibernation and quickly recovers body temperature in arousal phase. Project supported by the National Natural Science Foundation of China (Grant Nos. 39230060 and 39570100)     

Mechanism of chaperone function in small heat shock proteins: dissociation of the HSP27 oligomer is required for recognition and binding of destabilized T4 lysozyme

Mammalian small heat shock proteins (sHSP) form polydisperse and dynamic oligomers that undergo equilibrium subunit exchange. Current models of their chaperone activity hypothesize that recognition and binding of protein non-native states involve changes in the oligomeric state. The equivalent thermodynamic representation is a set of three coupled equilibria that includes the sHSP oligomeric equilibrium, the substrate folding equilibrium, and the equilibrium binding between the sHSP and the substrate non-native states. To test this hypothesis and define the binding-competent oligomeric state of human Hsp27, we have perturbed the two former equilibria and quantitatively determined the consequences on binding. The substrate is a set of T4 lysozyme (T4L) mutants that bind under conditions that favor the folded state over the unfolded state by 10(2)-10(4)-fold. The concentration-dependent oligomer equilibrium of Hsp27 was perturbed by mutations that alter the relative stability of two major oligomeric states including phosphorylation-mimicking mutations that result in the dissociation to a small multimer over a wide range of concentrations. Correlation of binding isotherms with size exclusion chromatography analysis of the Hsp27 oligomer equilibrium demonstrates that the multimer is the binding-competent state. Binding occurs through two modes, each characterized by different affinity and number of binding sites, and results in T4L.Hsp27 complexes of different hydrodynamic properties. Mutants of the Hsp27 phosphorylation mimic that reverse the reduction in oligomer size also reduce the extent of T4L binding. Taken together, these results suggest a central role for the oligomeric equilibrium in regulating the chaperone activity of sHSP. The mutants identify sequence features important for modulating this equilibrium.