鸡NRG4基因组及转录本结构分析

神经调节蛋白4(neuregulin 4,NRG4)是一个重要的脂肪细胞因子,在维持哺乳动物能量平衡、调节糖脂代谢和预防非酒精性脂肪性肝病中起着非常重要的作用。目前,人NRG4基因的基因组结构、转录异构体和蛋白异构体等已有深入的研究。本实验室前期研究显示,鸡脂肪组织也表达NRG4,但是目前有关鸡NRG4(chicken NRG4,cNRG4)基因的基因组结构、转录异构体和蛋白异构体尚不清楚。为此,本研究采用RACE(rapid-amplification of cDNA ends)和RT-PCR(reverse transcription-PCR)等技术,系统开展了cNRG4基因的基因组和转录本的结构分析。结果发现,cNRG4基因编码区很小,但该基因却非常复杂,存在选择性转录起始位点、选择性拼接、内含子滞留、隐匿外显子和选择性多聚腺苷酸化,这导致cNRG4基因产生4种不同的5ʹUTR异构体(cNRG4 A、cNRG4 B、cNRG4 C和cNRG4 D)和6种不同的3ʹUTR异构体(cNRG4 a、cNRG4 b、cNRG4 c、cNRG4 d、cNRG4 e和cNRG4 f)。基因组结构分析发现,cNRG4基因跨越基因组21,969 bp(Chr.10:3,490,314~3,512,282),由11个外显子和10个内含子构成。与NCBI数据库中的cNRG4基因mRNA序列(NM_001030544.4)相比,本研究发现了cNRG4基因的2个新外显子和1个隐匿外显子。生物信息学分析、RT-PCR、克隆和测序分析发现,cNRG4基因能编码3种蛋白异构体(cNRG4-1、cNRG4-2和cNRG4-3)。本研究为进一步开展cNRG4基因的功能和调控研究奠定了基础。

Design of the rare-earth-containing materials based on the micro-alloying phase equilibria, phase diagrams and phase transformations

Rare-earth(RE)elements,known as“industrial vitamins”,have permeated modern lives,especially in high-tech applications.Although the RE elements possess close chemical similarities and have been treated as“one element”in the periodic table,their characteristics differ from each other.The RE microalloying effect is the crux to ameliorate the physicomechanical and thermochemical properties of materials,thereby the study of RE-related phase diagrams becomes indispensable to the design and optimization of RE-containing materials.However,in reality,the knowledge base in this area is considerably scarce compared with that of other commonly-used elements.In this work,the phase equilibria,phase diagrams,phase transformations,and some recent examples of RE-containing materials design are summarized,with which one can predict the RE solubilities,the RE precipitates,as well as the corresponding service behaviors.The attainment of enhanced materials’properties suggests that the thermodynamic rules extracted from the phase diagrams could serve as fundamental criteria for the successful development of novel RE-containing materials.

Efficient prediction of corrosion behavior in ternary Ni-based alloy systems:Theoretical calculations and experimental verification

Pourbaix diagrams are calculated to describe electrochemical processes for alloys in aqueous solution.With the multi-component differentiation of alloy systems,the construction of Pourbaix diagrams is fac-ing challenges,especially for non-single-phase alloy systems.In this study,the simultaneous construction of phase diagrams and Pourbaix diagrams were implemented for predicting the evolution of the phases in the immune and passive regions.The CALPHAD(CALculation of PHAse Diagram)approach was used to quickly access the Gibbs free energies of various phases and the chemical potential of the elements in the phases from the thermodynamic database of the Ni-Si-Al-Y system.The corrosion behavior of two typical Ni-Al-Si and Ni-Al-Y systems was investigated.Si and Y were added to Ni-based alloys to produce the solid solutions L12-Ni_(3)(Al,Si)and L12-Ni_(3)Al+Ni_(5)Y,respectively.Calculations showed that NiO and Al_(2)O_(3)make up the passive area of the Ni_(3)Al 1 alloy.The introduction of SiO_(2)and Y(OH)3 in the passive region separately helped to minimize the alloys’susceptibility to corrosion.However,Si reduced the thermody-namical possibility of NiO for mation in the passive film,and the addition of Y caused extreme galvanic corrosion.Experiments on Ni-based alloys validated the results through electrochemical corrosion.It was also discovered that the presence of Ni_(5)Y produced galvanic corrosion and that Si reduced the oxide in the passive film,causing pitting corrosion.The corrosion prediction of the quaternary alloys indicates that the solid solution of Si in Ni_(5)Y reduces the galvanic corrosion effect and the dissolution of passive film.The current work demonstrates that phase diagrams and Pourbaix diagrams may be efficiently and accurately predicted using a well-constructed thermodynamic database,which has major implications for future studies on the corrosion behavior of multi-component alloys.

High-temperature wear mechanisms of TiNbWN films:Role of nanocrystalline oxides formation

Réfractory high/medium entropy nitrides(HENs/MENs)exhibit comprehensive application prospects as protective films on mechanical parts,particularly those subjected to sliding contacts at elevated temperatures.In this study,a new MEN system TiNbWN,forming a single fc solution,is designed and its wear performance at temperatures ranging from 25 to 750℃is explored.The wear mechanisms can be rationalized by examining the subsurface microstructural evolutions using the transmission electron microscopy as well as calculating the phase diagrams and interfacial adhesion behavior employing calculation of phase diagram(CALPHAD)and density functional theory(DFT).To be specific,increased wear losses occur in a temperature range of 25-600℃,being predominantly caused by the thermally-induced hardness degradation;whereas at the ultimate temperature(750℃),the wear loss is refrained due to the formation of nanocrystalline oxides(WnO_(3n-2r)TiO_(2),and TiOx),as synergistically revealed by microscopy and CALPHAD,which not only enhance the mechanical properties of the pristine nitride film,but also act as solid lubricants,reducing the interfacial adhesion.Thus,our work delineates the role of the in situ formed nanocrystalline oxides in the wear mechanism transition of TiNbWN thin films,which could shed light on the high-temperature wear behavior of refractory HEN/MENfilms.