An Efficient Markerless Deletion System Suitable for the Industrial Strains of Streptomyces

( Jianxin Dong ),( Jiaxiu Wei ),( Han Li ),( Shiyao Zhao ),( Wenjun Guan ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.12

The genus Streptomyces is intensively studied due to its excellent ability to produce secondary metabolites with diverse bioactivities. In particular, adequate precursors of secondary metabolites as well as sophisticated post modification systems make some high-yield industrial strains of Streptomyces the promising chassis for the heterologous production of natural products. However, lack of efficient genetic tools for the manipulation of industrial strains, especially the episomal vector independent tools suitable for large DNA fragment deletion, makes it difficult to remold the metabolic pathways and streamline the genomes in these strains. In this respect, we developed an efficient deletion system independent of the episomal vector for large DNA fragment deletion. Based on this system, four large segments of DNA, ranging in length from 10 kb to 200 kb, were knocked out successfully from three industrial Streptomyces strains without any marker left. Notably, compared to the classical deletion system used in Streptomyces, this deletion system takes about 25% less time in our cases. This work provides a very effective tool for further genetic engineering of the industrial Streptomyces.

Study of stability and evolution indexes of gobs under unloading effect in the deep mines

Fu, Jianxin,Song, Wei-Dong,Tan, Yu-Ye Techno-Press 2018 Geomechanics & engineering Vol.14 No.5

The stress path characteristics of surrounding rock in the formation of gob were analysed and the unloading was solved. Taking Chengchao Iron Mine as the engineering background, the model for analysing the instability of deep gob was established based on the mechanism of stress relief in deep mining. The energy evolution law was investigated by introducing the local energy release rate index (LERR), and the energy criterion of instability of surrounding rock was established based on the cusp catastrophe theory. The results showed that the evolution equation of the local energy release energy of the surrounding rock was quartic function with one unknown and the release rate increased gradually during the mining. The calculation results showed that the gob was stable. The LERR per unit volume of the bottom structure was relatively smaller, which mean the stability was better. The LERR distribution showed that there was main energy release in the horizontal direction and energy concentration in the vertical direction which meet the characteristics of deep mining. In summary, this model could effectively calculate the stability of surrounding rock in the formation of gob. The LERR could reflect the dynamic process of energy release, transfer and dissipation which provided an important reference for the study of the stability of deep mined out area.

SIRT5-related desuccinylation modification of AIFM1 protects against compression-induced intervertebral disc degeneration by regulating mitochondrial homeostasis

Mao Jianxin,Wang Di,Wang Dong,Wu Qi,Shang Qiliang,Gao Chu,Wang Huanbo,Wang Han,Du Mu,Peng Pandi,Jia Haoruo,Xu Xiaolong,Wang Jie,Yang Liu,Luo Zhuojing 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Mitochondrial dysfunction plays a major role in the development of intervertebral disc degeneration (IDD). Sirtuin 5 (SIRT5) participates in the maintenance of mitochondrial homeostasis through its desuccinylase activity. However, it is still unclear whether succinylation or SIRT5 is involved in the impairment of mitochondria and development of IDD induced by excessive mechanical stress. Our 4D label-free quantitative proteomic results showed decreased expression of the desuccinylase SIRT5 in rat nucleus pulposus (NP) tissues under mechanical loading. Overexpression of Sirt5 effectively alleviated, whereas knockdown of Sirt5 aggravated, the apoptosis and dysfunction of NP cells under mechanical stress, consistent with the more severe IDD phenotype of Sirt5 KO mice than wild-type mice that underwent lumbar spine instability (LSI) surgery. Moreover, immunoprecipitation-coupled mass spectrometry (IP-MS) results suggested that AIFM1 was a downstream target of SIRT5, which was verified by a Co-IP assay. We further demonstrated that reduced SIRT5 expression resulted in the increased succinylation of AIFM1, which in turn abolished the interaction between AIFM1 and CHCHD4 and thus led to the reduced electron transfer chain (ETC) complex subunits in NP cells. Reduced ETC complex subunits resulted in mitochondrial dysfunction and the subsequent occurrence of IDD under mechanical stress. Finally, we validated the efficacy of treatments targeting disrupted mitochondrial protein importation by upregulating SIRT5 expression or methylene blue (MB) administration in the compression-induced rat IDD model. In conclusion, our study provides new insights into the occurrence and development of IDD and offers promising therapeutic approaches for IDD.

The enhanced photothermal effect of graphene/conjugated polymer composites: photoinduced energy transfer and applications in photocontrolled switches

Meng, Dongli,Yang, Shaojun,Guo, Liang,Li, Guoxing,Ge, Jiechao,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.92

<P>Composites prepared by grafting poly(3-hexylthiophene) (P3HT) onto the surfaces of reduced graphene oxide (RGO) (RGO-<I>g</I>-P3HT) exhibit an enhanced photothermal effect due to photoinduced energy transfer from P3HT to RGO. A remote photo-controlled electrical switch was prepared using RGO-<I>g</I>-P3HT as a photothermal layer.</P> <P>Graphic Abstract</P><P>Photoinduced energy transfer from a conjugated system to graphene sheets enables the enhanced photothermal effect of graphene-based composites. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc06849a'> </P>

Source term inversion of nuclear accidents based on ISAO-SAELM model

Xiao Dong,Zhang Zixuan,Li Jianxin,Fu Yanhua 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.9

The release source term of radioactivity becomes a critical foundation for emergency response and accident consequence assessment after a nuclear accident Rapidly and accurately inverting the source term remains an urgent scientific challenge. Today source term inversion based on meteorological data and gamma dose rate measurements is a common method. But gamma dose rate actually includes all nuclides information, and the composition of radioactive nuclides is generally uncertain. This paper introduces a novel nuclear accident source term inversion model, which is Improve Snow Ablation Optimizer-Sensitivity Analysis Pruning Extreme Learning Machine (ISAO-SAELM) model. The model inverts the release rates of 11 radioactive nuclides (I-131, Xe-133, Cs- 137, Kr-88, Sr-91, Te-132, Mo-99, Ba-140, La-140, Ce-144, Sb-129). It does not require the use of the physical field of the reactor to obtain prior information and establish a dispersion model. And the robustness is validated through noise analysis test. The mean absolute errors of the release rates of 11 nuclides are 15.52 %, 15.28 %, 15.70 %, 14.99 %, 14.85 %, 15.61 %, 15.96 %, 15.42 %, 15.84 %, 15.13 %, 17.72 %, which show the significant superiority of ISAO-SAELM. ISAO-SAELM model not only achieves notable advancements in accuracy but also receives validation in terms of practicality and feasibility.

Creep Failure and Damage Mechanism of Inconel 718 Alloy at 800–900 °C

Kai Chen,Jianxin Dong,Zhihao Yao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The creep behavior and damage mechanisms of 718 alloys were investigated at 800–900 °C in air. The fracturemorphology and microstructure evolution were observed by optical, scanning and transmission electron microscope. Besides,the creep damage tolerance (λ) and creep strain evolution curve were also calculated. The results showed that the creep curvesof 718 alloys at 800 or 850 °C consisted of primary and tertiary stages, while the steady-state region became apparent at900 °C. The apparent creep activation energy of 718 alloy was in the range from 446.3 to 491.8 kJ/mol. The alloy presentedductile fracture at 800 °C due to the nucleation, growth and linkage of creep voids. However, the failure of alloys at 850 or900 °C presented necking to a point due to the microstructure degradation. Further investigations showed the softening ofmaterials and the loss of mechanical performance could be mainly attributed to the coarsening or decrease of strengtheningprecipitates. Above 850 °C, it was found that γ′ phases would dissolve into matrix and stress promoted the re-dissolution ofγ′ phases or led to the break of δ phases. Moreover, the creep strain evolution curves indicated that 718 alloys kept a relativestable state at 800–900 °C when the strain fraction was below 1.

Stronger plasticity of leaf characteristics is associated with better shade adaptation in Calycanthaceae

Chao Zhang,Jianxin Fu,Bin Dong,Lihua Zhou,Hongbo Zhao 한국원예학회 2020 Horticulture, Environment, and Biotechnology Vol.61 No.6

To understand how Calycanthaceae species adapt to diff erent light levels, we examined the responses of leaf structure, chlorophyll(Chl) content, and Chl fl uorescence of fi ve Calycanthaceae species to diff erent light conditions. With the reductionof light irradiance, total leaf thickness of Sinocalycanthus chinensis signifi cantly decreased, and that of Chimonanthus nitenswas generally the same. The other three species, Ch. praecox , Ch. salicifolius , and Calycanthus fl oridus var. glaucus , showedmoderate plasticity of leaf structure. With shade treatments, the Chl a content in the leaves of Ch. nitens increased, whilethat in Ch. salicifolius decreased. However, the Chl a content in Ch. praecox , Ca. fl oridus var. glaucus , and S. chinensis wasnot changed with decreased light levels. Leaves of four species (except Ch. salicifolius ) showed higher Chl b content andtotal Chl content, and leaves of all fi ve species showed a lower Chl a / b ratio in shade. The maximal quantum effi ciency ofphotosystem II (PSII) (F v /F m ) and the eff ective quantum yield of PSII (Φ PSII ) in S. chinensis were the same regardless of thelight regime, but those of the other four species were signifi cantly lower in full sunlight. Another Chl fl uorescence parameter,non-photochemical Chl fl uorescence quenching, was signifi cantly higher in full sunlight. Our results revealed that among thefi ve Calycanthaceae species, S. chinensis exhibited the highest plasticity of leaf structure in response to diff erent irradiancesand Ch. nitens was considered to have the highest shade tolerance.

High - Temperature Materials : INVESTIGATION ON HIGH TEMPERATURE STRUCTURE INSTABILITY AND STRUCTURE STABILITY IMPROVEMENT OF NICKEL - BASE SUPERALLOY INCONEL 718

Xishan Xie,Jianxin Dong,Shouhua Zhang,Mengzhe Chen,John F . Radavich 대한금속재료학회 ( 구 대한금속학회 ) 1995 Advanced Material and Processing Vol.3 No.-

Exogenous Sugars Involvement in Senescence and Ethylene Production of Tree Peony ‘Luoyang Hong’ Cut Flowers

Chao Zhang,Miao Liu,Jianxin Fu,Yanjie Wang,Li Dong 한국원예학회 2012 원예과학기술지 Vol.30 No.6

Sugars play important roles in petal senescence of cut flowers. In the Expt. 1 of this study, the effects of different concentrations of glucose (60, 90, and 120 g·L<SUP>-1</SUP>) and sucrose (30, 60, and 90 g·L<SUP>-1</SUP>) application on the vase life, rate of flower diameter increase, rate of flower weight increase and ethylene production of cut tree peony (Paeonia suffruticosa ‘Luoyang Hong’) were evaluated. At the earlier stage, treatments of different concentrations of glucose and sucrose all retarded the process of flower opening and inhibited the increase of flower diameter and weight, while senescence of flowers fed with different concentrations of glucose was delayed at later stage. Flowers treated with 90 g·L<SUP>-1</SUP> glucose displayed the longest vase life, which showed significant difference (P < 0.05) from those of flowers with the control and sucrose treatments. All treatments with glucose or sucrose not only retarded the decrease of flower diameter and weight, but also suppressed the ethylene production at the earlier stage and delayed the peak of ethylene evolution. In order to study the effect of exogenous sugar on the postharvest response of cut tree peony to ethylene, Expt. 2 was conducted. Cut flowers were treated with 90 g·L<SUP>-1</SUP> glucose for 4 hours before (GE) or after (EG) exposed to 10 μL·L<SUP>-1</SUP> ethylene for 4 hours. Generally, the opening process of flowers with GE and EG treatments was similar to that of the control, however GE treatment delayed flower senescence. Both GE and EG treatments improved flower diameter and weight, and GE treatment delayed the time of flower weight decrease. Besides, GE delayed climacteric ethylene evolution for 8 hours. All above suggest that exogenous sugars delay tree peony ‘Luoyang Hong’ cut flower senescence and extend flower vase life through their roles in the decrease of water loss and the suppression of sensitivity to ethylene and ethylene production.

Controlled Growth of Well-Defined Conjugated Polymers from the Surfaces of Multiwalled Carbon Nanotubes: Photoresponse Enhancement <i>via</i> Charge Separation

Hou, Wenpeng,Zhao, Ning-Jiu,Meng, Dongli,Tang, Jing,Zeng, Yi,Wu, Yu,Weng, Yangziwan,Cheng, Chungui,Xu, Xiulai,Li, Yi,Zhang, Jian-Ping,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin American Chemical Society 2016 ACS NANO Vol.10 No.5

<P>The installation of heterojunctions on the surfaces of carbon nanotubes (CNTs) is an effective method for promoting the charge separation processes needed for CNT-based electronics and optoelectronics applications. Conjugated polymers are proven state-of-the-art candidates for modifying the surfaces of CNTs. However, all previous attempts to incorporate conjugated polymers to CNTs resulted in unordered interfaces. Herein we show that well-defined chains of regioregular poly(3-hexylthiophene) (P3HT) were successfully grown from the surfaces of multiwalled CNTs (MWNTs) using surface-initiated Kumada catalyst-transfer polycondensation. The polymerization was found to proceed in a controlled manner as chains of tunable lengths were prepared through variation of the initial monomer-to-initiator ratio. Moreover, it was determined that large-diameter MWNTs afforded highly ordered P3HT aggregates, which exhibited a markedly bathochromically shifted optical absorption due to a high grafting density induced planarization of the polymer chains. Using ultrafast spectroscopy, the heterojunctions formed between the MWNTs and P3HT were shown to effectively overcome the binding energy of excitons, leading to photoinduced electron transfer from P3HT to MWNTs. Finally, when used as prototype devices, the individual MWNT-g-P3HT core-shell structures exhibited excellent photoresponses under a low illumination density.</P>