温度和pH对洞庭鲇鱼消化酶活性的影响

采用酶学分析方法研究了温度和pH对洞庭鲇鱼蛋白酶、脂肪酶和淀粉酶活力的影响。结果表明,在设定的温度和pH范围内,鲇鱼各消化酶的活力均随着温度和pH的升高呈现先升后降的变化趋势。其中,胃蛋白酶的最适温度为40℃,肝胰脏、前肠、中肠和后肠蛋白酶的最适温度为45℃;脂肪酶的最适温度均为35℃;胃淀粉酶的最适温度为35℃,其他部位均为30℃。胃、肝胰脏、前肠、中肠和后肠蛋白酶的适宜pH分别为2.0、8.5、7.5、8.0和8.0;脂肪酶的适宜pH均为7.5;淀粉酶肝胰脏的适宜pH为7.5,其余部位均为7.0。鲇鱼各消化酶活力存在器官特异性。在最适温度下,蛋白酶活力顺序为前肠>肝胰脏>胃>中肠>后肠,脂肪酶的活力顺序均为肝胰脏>胃>前肠>中肠>后肠,淀粉酶的活力顺序为肝胰脏>前肠>中肠>后肠>胃,各部位之间差异显著(P<0.05)。     

牛蛙主要消化酶的分布及pH和温度对消化酶活力的影响

研究了牛蛙消化系统蛋白酶、脂肪酶、淀粉酶和纤维素酶的分布情况以及pH和温度对这些消化酶活力的影响.结果表明:在各自生理pH值下,牛蛙消化系统不同部位蛋白酶活力大小顺序依次为胰脏>胃>中肠>食道>前肠>后肠,胃、肠和胰脏蛋白酶的最适pH值分别为2.2、7.4和9.6,最适温度分别为45℃、50℃和45℃.脂肪酶活力大小顺序依次为胰脏>后肠>中肠>前肠>胃>食道,胃、肠和胰脏脂肪酶的最适pH值分别为2.2、7.4和8.0,最适温度均为50℃.淀粉酶活力大小顺序依次为胰脏>中肠>后肠>前肠>胃>食道,胃、肠道和胰脏淀粉酶的最适pH分别为7.0、8.0和9.6,最适温度均为35℃.在牛蛙消化系统未检测到明显纤维素酶活力.     

额尔齐斯河野生丁(鐬)蛋白酶、淀粉酶活性的研究

目的:研究温度、pH、金属离子对新疆额尔齐斯河野生丁(鐬)消化道蛋白酶、淀粉酶活性的影响.方法:酶学和生化法.结果:丁(鐬)蛋白酶活性,后肠＞前肠＞中肠＞肝胰脏;淀粉酶活性,后肠＞中肠＞前肠＞肝胰脏.肠道、肝胰脏蛋白酶的最适温度分别为35℃、40℃,淀粉酶的最适温度均为40℃.消化道各部位蛋白酶、淀粉酶的体外最适pH为7.5.在试验的离子浓度范围,高浓度Ag 、Cu2 抑制酶活力;高浓度Fe3 、Mg2 、Ca2 促进酶活力;Pb 、Ba2 对消化道酶活力影响依浓度和部位而变.结论:消化酶最适温度均高于所处环境温度,最适pH值变化范围偏碱性;不同浓度金属离子对丁(鐬)消化道各部位蛋白酶、淀粉酶活力高低表现出不同的变化趋势.     

温度对兰州鲇消化酶活性的影响

测定了兰州鲇(Silurus lanzhouensis)胃、肝胰脏、前肠、中肠、后肠在不同温度(15℃、20℃、25℃、30℃、37℃4、2℃、47℃)条件下的蛋白酶、淀粉酶和脂肪酶的活性。结果表明,随温度的升高,各种酶活性的变化均表现为先增高后下降直至不能检出。消化道各部位蛋白酶的最适温度均为42℃;淀粉酶的最适温度除胃和肝胰脏为37℃外,其他部位均为30℃;脂肪酶的最适温度除后肠为30℃外,其他部位均为25℃。消化酶的最适温度高于其生活水域的水温,反映出消化酶作为酶蛋白的耐热性。最适温度下,蛋白酶活性前肠≈中肠>后肠>肝胰脏≈胃;淀粉酶活性前肠>中肠>肝胰脏>胃>后肠;脂肪酶活性中肠>后肠>前肠≈肝胰脏>胃。研究结果还表明,前肠和中肠是兰州鲇消化蛋白的主要部位,中肠是其消化脂肪的主要部位,而前肠是其消化淀粉的主要部位。在消化酶表现出活性的温度范围内,蛋白酶活性明显高于淀粉酶活性。实验还表明脂肪酶具有活性的温度范围较蛋白酶和淀粉酶窄。     

虎纹蛙消化道淀粉酶和脂肪酶活力研究

以酶学分析方法研究了虎纹蛙消化道淀粉酶和脂肪酶的分布以及pH和温度对这两种消化酶活力的影响。结果表明：在各自生理pH值条件下,虎纹蛙消化道不同部位淀粉酶活力大小顺序依次为前肠〉中肠〉后肠〉食道〉胃,胃和肠淀粉酶最适pH值分别为8．6和7．0,最适温度分别为35℃和40℃。脂肪酶活力大小顺序依次为中肠〉后肠〉前肠〉胃〉食道,各部位之间差异显著（P〈0．05）,胃和肠脂肪酶的最适pH值均为9．0,最适温度分别为50℃和55℃。     

温度对虎斑颈槽蛇消化酶活性的影响

研究了不同温度下虎斑颈槽蛇胃、胰腺、小肠的蛋白酶、淀粉酶、脂肪酶的活性。结果表明,随着温度的升高,各种酶的活性在一定范围之内均表现为升高。在不同组织中同一种酶活性存在差异。3种组织中,蛋白酶的最适温度均为40℃;胃和胰腺淀粉酶的最适温度为35℃,小肠淀粉酶为30℃;胰腺脂肪酶的最适温度为30℃,小肠脂肪酶为35℃。     

棘腹蛙消化道脂肪酶的分布及pH和温度对脂肪酶活力的影响

采用聚乙烯醇橄榄油乳化液水解法,测定了棘腹蛙消化道不同部位的脂肪酶活力,研究了pH和温度对脂肪酶活力的影响。结果显示,棘腹蛙消化道不同部位脂肪酶活力依次为回肠>直肠>十二指肠>胃>食道。pH和温度显著影响脂肪酶的活力,二者对脂肪酶活力影响的关系曲线均呈现为单峰型,食道、胃和肠道脂肪酶活力的最适pH值分别为5.0、5.0和7.5,最适温度均为35℃。     

四株冰川雪细菌产酶能力的初步研究

目的:从青藏高原冰川雪中筛选出一菌多酶的菌株.方法:对恢复出的4个细菌,通过平板透明法研究其产淀粉酶、脂肪酶和蛋白酶的特性.结果:LHG-C-9为惟一可以产淀粉酶的菌株,所产脂肪酶活性最高.4个菌株均不产蛋白酶.结论:LHG-C-9最适生长温度为15℃,属于耐冷菌.对该菌所产淀粉酶和脂肪酶的性质进行了初步研究,其随产淀粉酶的最适作用温度为50℃;最佳产酶pH值为7.0,该pH值所产酶活为83.9U/mL;在60℃的高温下温浴10min后酶活为0%.该菌株所产脂肪酶的最适作用温度为20℃;最佳产酶pH值为7.0,该pH值所产酶活为9.2U/mL;50℃温浴1h后酶活力不足34%.     

云斑尖塘鳢消化酶活力的研究

本文采用酶学分析方法研究了云斑尖塘鳢在正常摄食状态与饥饿的状态下胃、肠及肝胰脏组织中蛋白酶、淀粉酶和脂肪酶的活性。结果显示,在30℃的条件下,正常摄食组样本在酸性条件下的蛋白酶活力表现为:胃后肠肝胰脏前肠,中性和碱性条件下:后肠肝胰脏前肠及胃;饥饿组样本仅有胃表现出较高的酸性蛋白酶活性,其他器官的蛋白酶活性均很低。在正常和饥饿实验组中肝胰脏的淀粉酶活性均高于其他器官,胃肠的淀粉酶活性均较低。正常摄食组中脂肪酶活力后肠肝胰脏;而在饥饿组中仅有肝胰脏检测到脂肪酶活性。结果表明,云斑尖塘鳢适度饥饿组较正常摄食组消化酶活性大幅降低;其高蛋白酶活力及中等脂肪酶活力与其肉食性相一致;此外云斑尖塘鳢也具备少量的淀粉消化能力。     

温度和pH对橄榄蚶消化酶活性的影响

采用酶学分析方法,测定了温度和pH对橄榄蚶蛋白酶、淀粉酶、纤维素酶活力的影响。结果表明:温度和pH显著影响橄榄蚶蛋白酶、淀粉酶和纤维素酶的活力;蛋白酶、淀粉酶和纤维素酶的最适温度分别为60℃、40℃和30℃～40℃,最适pH分别为3.6、5.2和6.0。橄榄蚶3种消化酶活性大小为淀粉酶>蛋白酶>纤维素酶。     

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.