体外培养的哺乳动物细胞的葡萄糖和谷氨酰胺代谢

综述体外培养哺乳动物细胞的葡萄糖和谷氨酰胺代谢。大部分的葡萄糖通过糖酵解途径为细胞提供中间代谢物质和能量 ,最终生成乳酸 ,只有很少部分进入TCA循环和磷酸戊糖途径。谷氨酰胺通过谷氨酰胺酶生成谷氨酸 ,并进一步通过谷氨酸脱氢酶或转氨酶生成α -酮戊二酸进入TCA循环 ,为细胞提供中间代谢物质和能量。糖酵解和谷氨酰胺代谢 (glutaminolysis)受葡萄糖和谷氨酰胺的影响而相互调节。     

L-缬氨酸生物合成中的代谢流量分析

应用流量平衡模型 ,通过物料衡算和MATLAB线性规划方法得到了发酵中后期L 缬氨酸合成过程的代谢流量分步。代谢流分析结果表明 ,在分批培养生成L 缬氨酸的过程中 ,有62 8%的葡萄糖进入糖酵解途径生成L 缬氨酸 ,38 2 %进入HMP途径 ,仅 9 2 %的碳架进入TCA循环。实验条件下的代谢流 (58)与理想代谢流 (92 31 )相比 ,仍应从遗传改造和发酵控制方面降低TCA循环的代谢流 ,减少副产氨基酸的生成来进一步提高缬氨酸的产率。     

不同溶氧条件下L-苏氨酸生物合成菌株的代谢流量分析

[目的]探索L-苏氨酸生物合成机理及影响因素.[方法]建立了大肠杆菌L-苏氨酸的代谢流平衡模型,应用MATLAB软件计算出不同溶氧条件下发酵中后期代谢网络的代谢流分布及理想代谢流分布.[结果]5%溶氧条件下,25.5%碳架进入HMP途径,74.5%碳架进入糖酵解途径,获得33.9%质量转化率;20%溶氧条件下,58.08%碳架进入HMP途径,41.92%碳架进入糖酵解途径,获得46.5%质量转化率;[结论]与理想代谢流(88.23%质量转化率)相比,应从菌种改造和发酵控制方面通过改变6-磷酸葡萄糖异构酶借以增加HMP途径代谢流量,通过增加磷酸烯醇式丙酮酸羧化反应代谢流提高天冬氨酸族合成代谢流,减少TCA循环代谢流量,从而达到减少副产物生成,增加L-苏氨酸生物合成的目的.     

L-色氨酸生物合成的代谢流量分析

建立了谷氨酸棒杆菌合成L色氨酸(LTry)的代谢流量平衡模型,应用该模型计算出发酵中后期的代谢流分布并通过MATLAB软件线性规划得到Try理想代谢流分布。结果表明75.15%的碳架进入糖酵解,24.85%的碳架进入HMP途径;但与理想代谢流相比,应从遗传改造和发酵控制方面降低 TCA循环的代谢流,减少副产氨基酸的生成,摸索最适的溶氧控制对提高Try产率至关重要。     

重组CHO细胞培养过程中氨对细胞代谢的影响

研究了重组CHO细胞批培养过程中,氨浓度对细胞的葡萄糖、谷氨酰胺及其它氨基酸代谢的影响。表明,细胞对葡萄糖和谷氨酰胺的得率系数随着氨浓度的增加而降低,起始氨浓度为566mmol/L的批培养过程与起始氨浓度为021mmol/L的批培养过程相比,细胞对葡萄糖和谷氨酰胺的得率系数分别下降了78%和74%,细胞对其它氨基酸的得率系数也分别下降了50%～70%。氨浓度的增加明显地改变了细胞的代谢途径,葡萄糖代谢更倾向于厌氧的乳酸生成。在谷氨酰胺的代谢过程中,谷氨酸经谷氨酸脱氢酶进一步生成α酮戊二酸的过程受到了氨的抑制,而氨对谷氨酸经谷氨酸转氨酶反应生成α酮戊二酸的过程有促进作用,但总体上谷氨酸进一步脱氨生成α酮戊二酸的反应受到了氨的限制。     

聚球藻7942混养培养中碳代谢与能量利用

为了考察聚球藻7942在混养条件下的能量利用效率,分别以葡萄糖和乙酸为碳源开展了聚球藻7942的混养培养研究,并在此基础上利用代谢通量分析方法对聚球藻7942混养条件下的碳代谢和能量利用进行了探讨。结果表明:葡萄糖和乙酸均能促进藻细胞生长,且乙酸促进藻细胞生长的作用更为明显;葡萄糖利用可明显增加藻细胞糖酵解途径中碳代谢流量,而乙酸利用则导致糖酵解途径中碳代谢流量减小,两种有机碳源均增加了柠檬酸循环中碳代谢流量;有机碳源导致藻细胞光化学效率下降,而葡萄糖较之乙酸降低藻细胞光化学效率更为明显。虽然混养条件下光能的贡献率要小于光自养,但基于能量的细胞得率和能量转换率均高于光自养,光自养和以葡萄糖、乙酸为碳源的混养中基于ATP生成的能量转换效率分别为6.81%、7.43%和8.77%。     

星形胶质细胞和神经元之间谷氨酸-谷氨酰胺的代谢偶联

谷氨酸-谷氨酰胺循环是星形胶质细胞和神经元代谢偶联最重要的途径之一。在中枢神经系统中葡萄糖经糖酵解和三羧酸循环,合成三羧酸循环的中间产物。神经元因缺乏丙酮酸羧化酶,不能由葡萄糖直接合成谷氨酸,而必须依赖于星形胶质细胞的三羧酸循环来产生作为谷氨酸前体的三羧酸循环中间代谢产物。星形胶质细胞的谷氨酸载体从突触间隙摄取谷氨酸,在星形胶质细胞中转变成谷氨酰胺并释放到细胞外,然后重新被神经元摄取,转变成谷氨酸进入新一轮的循环。本文介绍了该循环,以及星形胶质细胞谷氨酸载体的功能、特性及调控。     

添加TCA循环中间产物加速光滑球拟酵母积累丙酮酸

在维生素限制的条件下,研究了添加TCA循环中间产物对光滑球拟酵母多重维生素营养缺陷型菌株CCTCC M202019生长和积累丙酮酸的影响。该菌株能以TCA循环中间产物为唯一碳源进行生长,且在以葡萄糖、乙酸和TCA循环中间产物为复合碳源的平板上菌落数高于分别以葡萄糖和乙酸或TCA循环中间产物为唯一碳源时的菌落数。与其它TCA循环中间产物相比,草酰乙酸更能促进细胞的生长、提高丙酮酸产量和对葡萄糖的得率。草酰乙酸能够促进细胞生长,是因为T. glabrata CCTCC M202019菌株能够利用乙酸作为乙酰辅酶A供体。在含有100 g/L葡萄糖和6 g/L乙酸钠的培养基中再添加10 g/L草酰乙酸进行分批发酵实验,可使菌体浓度从11.8 g/L提高到 13.6 g/L,增长幅度为15%;丙酮酸对葡萄糖的得率(0.66 g/g)以及生产强度(1.19 g·L^{-1<、sup>·h-1<、sup>)分别高出6%和24%,使发酵结束时间提前8～12h。}     

L-色氨酸生物合成的代谢流量分析

建立了谷氨酸棒杆菌合成L-色氨酸(L-Try)的代谢流量平衡模型,应用该模型计算出发酵中后期的代谢流分布并通过MATLAB软件线性规划得到Try理想代谢流分布。结果表明75．15％的碳架进入糖酵解,24．85％的碳架进入HMP途径;但与理想代谢流相比,应从遗传改造和发酵控制方面降低TCA循环的代谢流,减少副产氨基酸的生成,摸索最适的溶氧控制对提高Try产率至关重要。     

酿酒酵母对数生长后期代谢重构的全基因组表达谱芯片分析

为了探讨酵母进入对数生长后期以后酒精生产速度降低的原因, 我们利用酵母表达谱芯片技术对酿酒酵母细胞从对数生长中期进入对数生长后期时的全基因组表达谱进行了分析, 发现酵母在对数生长中期的表达谱非常稳定, 而一旦进入对数生长后期, 则出现明显的代谢重构现象。许多氨基酸合成和代谢相关的基因、离子转移以及与能量的生成和储存等功能相关的基因出现了不同程度的上调; 而许多涉及酵母转座和DNA重组的基因则表达下调; 一些中心代谢途径也发生了代谢重构, 包括: 琥珀酸和a-酮戊二酸生成途径基因的一致上调, 都与氨基酸合成和代谢相关基因表达的结果相吻合。结果表明: 由于氨基酸合成的需求量增加, 进入对数生长后期酵母的代谢转向TCA循环和乙醛酸循环, 导致酒精的生产速率降低。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.