小麦叶内硝酸还原的代谢库

随营养液中No_3~-浓度升高,叶片内No_3~-总量、代谢库大小(NIPS)及硝酸还原酶(NR)活性均升高,其中MPS与NK活性呈同步变化;No_3~-浓度达2.0mmol/L时,两者趋于稳值;若再增加NO_3~-浓度,则被吸收的NO_3~-积累于液泡中,而代谢库中NO_3~-含量(MPS)与NO_3~-总量之比有一定程度降低。低氮(NO_3~-浓度为1.0 mmol/L)情况下,反应液中无NO_3~-时,叶片内NR活性品种间有差异,但在50 mmol/L NO_3~-反应液中则品种间无差异;NK活性高的品种鲁麦8号及品种321叶内有大的NO_3~-代谢库,反应液中NO_3~-对NR活性刺激程度低,代谢库NO_3~-含量与叶NO_3~-总量之比高,而叶组织长时间反应过程中其NR活性衰减速率低。     

NO_3~-上运和液泡内NO_3~-外流对小麦叶内硝酸还原酶活性的调节

NO_3~-亏缺能使叶片硝酸还原酶活性(NRA)和NO_3~-总量降低,而根部NO_3~-吸收及上运能力提高,以亏缺2d的幼苗最为明显,该幼苗经12hNO_3~-吸收,叶片的NRA高于未经亏缺的幼苗,但NO_3~-含量以后者为高,代谢库中NO_3~-含量前者高于后者。提高营养液中NO_3~-浓度,NO_3~-上运速率升高,叶片内NRA增加。叶片组织暗中无氧保温40min后,代谢库体积渐大,液泡内NO_3~-有外流产生;Cl~-可促使液泡内NO_3~-外流,代谢库中NO_3~-量增加,NRA升高。NRA在体内测定条件下,保温3h后,NO_2~-产生趋于稳值,NRA降至最低;系统中加KCl或KNO_3使NO_2~-产生趋于稳值的时间延长,且能提高NO_2~-积累总量。     

春化对油菜叶片硝酸还原酶活性的影响

油莱种子经春化后,其子叶NR活性提高了1.5～4.9倍,真叶展开、雌雄分化及开花期的NR活性也高于对照。去顶芽、高温中断及抑制剂处理证实春化是导致NR活性变化的原因。春化期间幼苗根部对NO_3~-吸收及叶片ATP含量的增加可能是NR活性升高的部分生理机制。     

甘氨酸对黄瓜幼苗硝酸盐吸收还原和硝态及氨态氮积累的影响（简报）

经甘氨酸溶液浸叶处理的黄瓜幼苗光下对NO_3~-的吸收和还原明显受到促进,地上部氨态氮积累增加,硝态氮减少,而根部硝态氮和氨态氮均增加。     

NaCl胁迫下硝酸盐对大麦幼苗根系Cl~-吸收的调节(简报)

在含20mmolL~(-1) 的 NaCl溶液中,当加入的NO_3~-浓度由0增加到10mmol L~(-1)时,两个耐盐性不同的大麦品种幼苗根系Cl~-吸收速率呈明显降低趋势。NO_3~-是Cl~- 吸收的竞争性抑制剂。在含200mmol L~(-1)NaCl的1/2 Hoagland培养液中,加入7.5～37.5mmolL~(-1)NO_3~-时,根系及地上部Cl~-含量降低,植株干物质积累增加.NO_3~-缓解盐胁迫的适宜浓度范围为[NO_3~-]/[Cl~-]=1/5～1/26。     

植物体内NO3^—可给性对硝酸还原酶活性的调节

评述植物叶片中NO_3~-可给性对活体硝酸还原酶(NR)活性的调节,指出根部NO_3~-的不断供给及液泡内NO_3~-的外流可以使细胞质内的NO_3~-维持一定水平,这对NR的诱导及整个NO_3~-还原系统高活力的稳定是必需的。NO_3~-对NR的诱导反映在NR的mRNA转录水平上。     

小麦吸收、累积硝酸根的品种间差异

小麦苗在弱光下吸收NO_3~-的速率在品种间观察不到有差异;在强光下,吸收速率在品种间有较大的差异。 小麦苗用0.2 mMKNO_3预处理3小时,再在强光下吸收,NO_3~-吸收速率在品种间的差异显著。品种间吸收速率的差异为:扬麦1号>扬麦3号,郑州3>郑州761号。 从NO_3-吸收动力学的资料来分析,在KNO_3浓度0.05～2 mM范围内,郑州761、郑州3号有较低的 Km(0.30、0.25 mM),能在低浓度溶液中有效地吸收 NO_3~-;扬麦1号、扬麦3号的Km为0.59及0.84 mM,在低浓度溶液中吸收NO_3~-将不如郑州761及郑州3号。但扬麦1号、扬麦3号的Vmax比郑州761、郑州3号为高,有利于在较高浓度溶液中吸收NO_3~-。 NO。一在第1叶内的积累,随吸收溶液浓度的提高而增加。积累量扬麦1号>扬麦3号。     

油菜素内酯对水稻幼苗硝酸还原酶活性的影响（简报）

油菜素内酯(BR)明显提高水稻幼苗的硝酸还原酶(NR)活性,并促进NO_3~-的吸收。环己亚胺(CHI)和脱落酸(ABA)都抑制 NR活性,而这些抑制不为 BR所逆转。BR和苄基腺嘌呤(BA)单独处理都促进NR活性,但两者不表现加成作用。     

外源亚精胺对高温胁迫下黄瓜幼苗氮素代谢的影响

以较为耐热的黄瓜品种‘津春4号’为试材,在人工气候箱中,采用石英砂培加营养液浇灌的栽培方式,研究了外源亚精胺( Spd)对高温胁迫(42℃)下黄瓜幼苗氮素代谢的影响.结果表明:短期高温胁迫处理,尤其是4h内,植株硝态氮含量降低而铵态氮含量升高;外源Spd预处理使幼苗体内硝态氮和铵态氮含量升高且硝酸还原酶(NR)活性增强.较长期高温胁迫处理下,幼苗根系中硝态氮含量升高但向地上部运输受阻,根系NR钝化,根系和叶片中铵态氮含量均显著升高;高温胁迫下喷施Spd,除进一步促进根系吸收硝态氮且向地上部运输外,根系和叶片NR活性亦有所升高,从较长期的效果看,外源Spd还具有防止铵态氮过度积累、促进幼苗体内氮素代谢趋于正常的作用.     

NaCl胁迫对大麦硝酸盐吸收和有关的酶活的影响

NaCl胁迫下,抗盐性弱的洋草麦对NO_3~-的吸收明显下降;而抗盐性强的鉴4对NO_3~-的吸收显著升高,对Cl~-的吸收则显著小于洋草麦。盐胁迫下大麦GS活力提高,GDH活力无明显变化。在低盐度下,鉴4NR活力变化较小,洋草麦则显著增加;高盐度下,两品种NR活力均迅速下降或丧失。NR活力与叶片的水势变化有显著相关。     

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.