中国林蛙变态蝌蚪对pH、盐度和碱度的适应性

在水温16～18℃的野外条件下,采用单因子急性毒性实验法,研究了水环境中pH、盐度和碱度对中国林蛙(Rana chensinensis)变态蝌蚪的毒性效应．结果表明,中国林蛙变态蝌蚪对pH的适应范围为4．3～9．7,最低耐受限3．6,最高耐受限10．7;对盐度的最高耐受限为9．98g·L^-1,适应盐度上限7．14g·L^-1,安全盐度上限1．70g·L^-1;对碱度的最高耐受限为19．96mmol·L^-1,适应碱度上限8．76mmol·L^-1。安全碱度上限2．41mmol·L^-1．野外变态蝌蚪饲养池水体pH应控制在6．5～8．5,盐度控制在2．0g·L^-1以下,碱度不超过4．0mmol·L^-1．中国林蛙变态蝌蚪是一种狭酸碱、低耐盐、低耐碱生物。     

壬基酚对中国林蛙蝌蚪生长发育的毒性效应

为评价壬基酚对中国林蛙(Rana chensinensis)蝌蚪的急性毒性,将26～28期的中国林蛙蝌蚪暴露于浓度为0.05～0.5 mg·L-1壬基酚(NP)的水体中进行急性毒性试验.结果表明:24、48、72、96h蝌蚪的死亡几率与浓度对数的回归方程分别为y=8.4087χ 10.202、y=9.5104χ 11.745、y=10.284χ 12.498、y=10.619,χ 13.095;半数致死浓度(LC50)分别为0.24、0.20、0.19、0.17 mg·L-1;安全浓度(SC)为0.017mg·L-1;96h的LC0为0.14 mg·L-1.证明林蛙蝌蚪的死亡几率与一定范围的NP浓度呈线性正相关.为探讨低浓度壬基酚对中国林蛙蝌蚪生长发育的影响,将26期林蛙蝌蚪分别在100、60、30、10μg·L-1 NP的水体中连续暴露直至完全变态,并以3、0.3 μg·L-1雌二醇(E2)作为阳性对照,分别统计林蛙蝌蚪暴露于NP和E2,中20、40d和完成变态后幼蛙的体质量、全长以及从26期到完全变态所需的时间.结果表明,NP浓度在100 μg·L-1以下,对林蛙蝌蚪不能致死.100、10 μg·L-1NP与3 μg·L-1E2的效应相似,均可滞后蝌蚪变态时间,降低蝌蚪变态后幼蛙的体质量.说明NP浓度在100μg·L-1以下不直接损伤蝌蚪机体,但可以通过干扰内分泌活动影响林蛙幼体的生长发育.     

pH和氨氮对橄榄蚶耐受性的影响

采用实验生态学方法,研究了pH和氨氮对橄榄蚶稚贝和成贝存活和耐受力的影响.结果表明:pH显著影响橄榄蚶稚贝和成贝的成活率,橄榄蚶稚贝适宜pH范闱为7.9～9.4,pH为8.5时存活最好,橄榄蚶成贝的适宜pH范围为5.2～9.4.氨氮浓度和毒性试验时间的相互作用显著影响橄榄蚶稚贝和成贝的成活率,氨氮浓度越高,其毒性越强.稚贝48 h、96 h的半致死浓度(TLm)为58.6 mg·L-1、50.0 mg·L-1,安全浓度(SC)为5.9 mg·L-1、5.0 mg·L-1、成贝48 h、96 h的TLm为618.7 mg·L-1、556.9 mg·L-1、SC为61.9 mg·L-1、55.7 mg·L-1.     

中国林蛙蝌蚪对碳酸盐碱度的适应性

为了解中国林蛙蝌蚪对碳酸盐碱度的适应性,在水温16～18℃、pH7．0～8．5的野外条件下,采用单因子静态急性毒性实验方法,进行了碳酸盐碱度对中国林蛙蝌蚪的急性毒性实验。结果表明：碳酸盐碱度对中国林蛙蝌蚪的24、48、72、96h半致死量(LD50)分别为14．13、11．92、9．98、7．07mmol／L,零致死量(LD0)分别为9．75、8．64、6．1l、3．79mmol／L,全致死量(LD100)分别为20．16、16．44、16．3l、13．22mmol／L,安全量(SD)为2．54mmol／L。野外蝌蚪饲养池水体碳酸盐碱度的适宜范围在1．0～3．0mmol／L。     

中国林蛙生长发育盐效应的研究进展

本文对中国林蛙受精卵、蝌蚪和幼蛙等不同发育阶段生长发育的盐效应进行了综述。盐度对不同发育阶段的中国林蛙均有影响。中国林蛙受精卵孵化的最适盐浓度范围为0~5 g/L,孵化率超过80%;在2~3 g/L盐浓度下孵化的中国林蛙雌性个体超过90%,孵化后中国林蛙蝌蚪的存活率没有显著变化;中国林蛙蝌蚪和变态幼蛙的安全盐度上限分别为2 g/L和1.5 g/L。这些研究结果为中国林蛙野生资源的保护和人工养殖提供了一定的理论基础。     

中国林蛙蝌蚪和大蟾蜍蝌蚪的最适温度、逃避温度及致死温度

报道了中国林蛙蝌蚪 (Ranachensinensis)和大蟾蜍蝌蚪 (Bufogargarizans)在不同驯化温度下的最适温度、逃避温度和致死温度的研究结果。将中国林蛙蝌蚪和大蟾蜍蝌蚪分别在 5、1 5和 2 5℃ 3个不同温度下驯养 3周 ,利用温度梯度装置观察记录 2种蝌蚪的最适温度、逃避温度和最高致死温度。结果表明 ,经过在 5、1 5和 2 5℃ 3个温度下的驯化 ,中国林蛙蝌蚪的最适温度范围分别为 1 3 . 5～ 1 8℃、2 0. 5～2 5℃和 2 3～ 2 7. 5℃ ;大蟾蜍蝌蚪的最适温度范围分别为 1 2～ 1 6 .5℃、2 1～ 2 5. 5℃和 2 2～ 2 6. 5℃。中国林蛙蝌蚪和大蟾蜍蝌蚪的最高致死温均在 3 7～ 3 8℃之间 ,最低致死温均为 0℃。驯化温度对最适温度影响显著 (P <0 .0 1 ) ,对致死温度则没有显著影响。驯化温度对中国林蛙蝌蚪和大蟾蜍蝌蚪的逃避温度产生的影响比最适温度的大。     

一株凝结芽孢杆菌产生糖脂的工艺研究

对分离出的一株凝结芽孢杆菌生产糖脂的摇瓶发酵工艺进行了优化和 1 0L罐发酵实验。适宜发酵条件为 :培养基由 6 %豆油、 3 5g/LNaNO3、 0 75g/L酵母膏以及一定量的无机盐组成 ,发酵温度 3 0℃ ,初始pH8 5 ,搅拌转数 1 5 0～ 2 4 0r/min ,发酵周期 96h。糖脂产量达到 7 0 73g/L。     

同一生境牛蛙与昭觉林蛙蝌蚪的食性比较

对采自昆明东北郊同一水塘的牛蛙和昭觉林蛙蝌蚪进行食性分析。结果表明 ,牛蛙蝌蚪Ⅰ、Ⅱ期的食物种类分别为 8大类 5 1种和 37种 ,而昭觉林蛙蝌蚪Ⅱ期的食物种类有 6大类 30种 ;两者的食物组成均以硅藻门、绿藻门、蓝藻门为主 ,但昭觉林蛙蝌蚪Ⅱ期与牛蛙蝌蚪Ⅰ期的摄食种类差异极显著 ,与牛蛙Ⅱ期的不显著。昭觉林蛙蝌蚪Ⅱ期与牛蛙蝌蚪Ⅰ、Ⅱ期的食物生态位重叠度分别为 0 6 95 2和 0 6 887,单位体重摄食的生物量分别是后两者的 10 96倍和 15 4 8倍 ,但百分率相似性指数并不高 (分别为 5 4 95 %和 5 8 11% )。与等重量牛蛙蝌蚪相比 ,昭觉林蛙蝌蚪食物量较大 ,即昭觉林蛙蝌蚪为生存所需要的生物量远高于牛蛙蝌蚪。本文结果及野外观察表明 ,昭觉林蛙与牛蛙蝌蚪存在较激烈的食物竞争 ,且前者处于不利地位。     

火焰兰的种子培养和试管育苗

1植物名称火焰兰(Renanthera CoCCinea). 2材料类别种子. 3培养条件种子萌发培养基:(1)VW;(2)VW 100 mL·L-1椰子乳;(3)KC;(4)KC 100 mL·L-1椰子乳(5)1/2MS;(6)MS.生根育苗培养基:(7)3 g·L-1花宝1号(美国Haponex公司产品,N:P:K=7:6:19) 2 g·L-1蛋白胨 2 g·L-1活性炭 0.5 mg·L-1NAA 0.2 mg·L-16-BA;(8)1 g·L-1花宝1号 1 g·L-1花宝2号(N:P:K=20:20:20) 2 g·L-1蛋白胨 2 g·L-1活性炭 0.5 mg·L-1NAA 0.2 mg·L-16-BA.以上培养基均附加1.5%蔗糖、0.6%琼脂,pH 5.2～5.4.培养温度为(25±2)℃,光照度1 500～2000lx,光照时间12 h·d-1.     

光合细菌产辅酶Q10发酵条件的研究

利用均匀设计原理进行实验设计 ,对光合细菌R .capsulatusMT1131产辅酶Q10培养基配方及培养条件进行优化 ,结果当培养基中酵母膏质量浓度为 3 .13g·L- 1 ,硫酸铵 0 .8g·L- 1 ,Mg2 + 0 .6 4g·L- 1 ,Fe2 + 45 .2mg·L- 1 ,Mn2 + 18mg·L- 1 ,Co2 + 16mg·L- 1 ,培养基初始pH值为 7.0时 ,于 30℃ ,光照强度为 2 0 0 0Lx条件下培养 4天后 ,菌体中辅酶Q10质量浓度由 15 .2 13mg·L- 1提高至 2 0 .36 5mg·L- 1 ,产量提高约 33.87%。     

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.     

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     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

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.     

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).     

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.