长牡蛎“海大2号”四倍体的人工诱导

为筛选适宜的四倍体诱导条件, 研究了细胞松弛素B(CB)浓度(0.3、0.5、0.7和0.9 mg/L)、起始诱导时间(5、10和15min)、诱导持续时间(10、15、20和25min)及三者的交互作用对长牡蛎“海大2号”四倍体诱导率(四倍体率)和D形幼虫率的影响, 并对诱导处理组获得的幼贝倍性进行检测分析, 进一步验证了研究诱导方法获得可存活长牡蛎“海大2号”四倍体幼贝的可行性。结果表明, CB浓度和起始诱导时间对长牡蛎“海大2号”四倍体率有显著影响(P<0.05), 而诱导持续时间对四倍体率影响不显著(P>0.05), 但是三者的交互作用对四倍体率有显著影响(P<0.05)。在CB浓度为0.5 mg/L、起始诱导时间为15min及诱导持续时间为20min时, 四倍体率有最大值为37.82%。CB浓度、起始诱导时间和诱导持续时间均对D形幼虫率有显著影响(P<0.05), 但是三者的交互作用对D形幼虫率没有显著影响(P>0.05)。增加CB浓度或延长诱导持续时间, D形幼虫率均呈降低的趋势; 起始诱导时间为5min时, D形幼虫率显著高于其他起始诱导时间。获得幼贝的两个诱导处理组的倍性检测结果显示, 长牡蛎“海大2号”四倍体率分别为2.22%和3.03 %, 与幼虫期相比四倍体率显著下降。通过对CB浓度、起始诱导时间及诱导持续时间进行优化, 可以筛选出适宜的长牡蛎“海大2号”四倍体诱导条件。研究结果为长牡蛎“海大2号”四倍体培育提供了重要的参考资料。     

细胞松弛素B和低盐诱导长牡蛎“海大3号”四倍体的效果比较

为探索细胞松弛素B(CB)和低盐抑制第一极体诱导长牡蛎“海大3号”四倍体的最佳条件,研究了CB浓度(0.2、0.4、0.6和0.8 mg/L)、低盐(6、8、10和12)及诱导持续时间(10min、15min、20min和25min)对卵裂率、孵化率、四倍体率和诱导效率指数的影响,并分析了幼虫生长和生存情况。结果表明,在CB浓度为0.6 mg/L,诱导持续时间为15min时,四倍体率为(65.69±2.47)%,诱导效率指数最大;在盐度为8,诱导持续时间为15min时,四倍体率为(38.77±2.69)%,诱导效率指数最大。CB和低盐诱导组前期壳高大于对照组,后期小于对照组, CB诱导组壳高显著大于低盐诱导组(P<0.05), CB和低盐诱导组幼虫平均日增长量分别为(14.2±1.08)和(10.49±0.60)μm/d,均小于对照组(15.43±1.08)μm/d; 2个诱导组存活率始终低于对照组,低盐诱导组前期存活率高于CB诱导组,后期低于CB诱导组。综合来看, CB诱导法在四倍体率、诱导效率指数、12d存活率和生长速度等方面效果较好,适用于诱导长牡蛎“海大3号”四倍体。     

罗氏沼虾四倍体诱导的研究

对罗氏沼虾卵子极体排出时间和第一次卵裂时间进行了观察,并在此基础上,采用热休克和细胞松弛素 B(C,B)两种诱导方法成功诱导出了罗氏沼虾四倍体。石蜡切片显示,当罗氏沼虾卵子完全成熟时,第一极体已经 排出。第二极体排出的时间约在受精后55min。经过雌性原核和雄性原核的联会,第一次卵裂的时间约在受精后 210-230min。设计了多种处理条件,其中热休克诱导罗氏沼虾四倍体的最好条件是:受精后210min,用40℃水温处 理胚胎1．5min,在这种条件下,最高可以得到35．86％的四倍体率;而C．B诱导罗氏沼虾四倍体的最好条件是:受精 后230min,用1．0mg/L的C．B处理胚胎10min,此时最高四倍体诱导率达33．78％。     

鱼类染色体组操作的研究 Ⅱ.静水压处理和静水压与冷休克结合处理诱导水晶彩鲫四倍体

采用静水压处理和静水压与冷休克结合处理两种方法进行了抑制第一次卵裂诱导水晶彩鲫四倍体的研究。水晶彩鯽受精卵在受精后(发育水温14—15℃)50、54、55和60min时的静水压(650kg/cm~2)处理(3min)组中都出现了四倍化胚胎,而在受精后48和48min以前的相同处理组中都没有观察到四倍化胚胎。在受精后(发育水温16-18℃)48、50、52、55、56和60min时的静水压与冷休克结合处理组中,也都出现了四倍化胚胎,且四倍化率比仅用静水压处理高,但存活率更低。在经过处理而发育形成的胚胎中,既有四倍体、次四倍体和4n/2n嵌合体,也有二倍体和次二倍体,并在一些次二倍体和次四倍体中期相中还观察到休克处理致使染色体断裂的痕迹——染色体片段。在抑制卵裂诱发加倍的效应期内,可能存在瞬间对休克耐受性较强的时期,而在此前后,对休克更为敏感。在少数处理组中,已筛选出了数尾四倍体鱼。文中还对鱼类四倍体的诱导技术、抑制卵裂诱发染色体组加倍的效应期以及四倍化胚胎的存活率和生命力等有关问题进行了分析和讨论。     

不同浸种条件对球花含笑播种出苗的影响

目的：球花含笑是云南特有珍贵树种，绿化观赏性佳，为解决其播种育苗中出苗率不高、出苗缓慢问题，研究了不同浸种条件对其播种后出苗率、出苗起始时间、出苗持续时间的影响，找出适宜的浸种条件。方法：采用单因素试验比较萘乙酸(NAA)、赤霉素(GA₃)、等浓度等体积赤霉素和萘乙酸混合液(1GA₃∶1NAA)浸种对出苗的影响；采用全因素试验比较不同浸种条件：NAA浓度(300 mg/L、500 mg/L、700 mg/L)，浸种时间(12 h、24 h)，温度(20℃、30℃)对出苗的影响。结果：单因素试验在激素浓度500 mg/L，时间12 h，温度20℃条件下，使用激素NAA浸种出苗率高，出苗起始时间早，出苗持续时间短。全因素试验使用激素NAA浸种，浓度500 mg/L，时间12 h，温度20℃出苗率最高；NAA浓度700 mg/L，时间12 h，温度20℃出苗起始时间最早；NAA浓度500 mg/L，时间24 h，温度20℃出苗持续时间最短。结论：为提高球花含笑出苗的效率，使用激素NAA浓度500 mg/L，时间12 h，温度20℃为最适宜浸种条件。     

中华绒螯蟹多倍体的诱导研究 : Ⅱ.热休克诱导中华绒螯蟹三倍体胚胎和四倍体 状幼体

采用热休克方法对中华绒螯蟹进行了三倍体、四倍体的人工诱导研究。结果表明,在卵子受精后（发育水温２０±１℃）１０～２５分钟,用３８～４１℃的高温处理１～２分钟,三倍体的平均诱导率为１０％～５０％,而对受精后３０分钟的卵子进行诱导,或在４０℃下处理超过２５分钟和处理温度高于４２℃诱导１５分钟的各试验组,均未检测到有三倍体胚胎。依据诱导三倍体的适宜诱导温度和处理时间,将受精后８１／２～９５／６小时的卵子用４０℃热休克处理１５分钟,均获得了一定比例的四倍体胚胎,其中四倍体最高诱导率为５２９６％。检查卵受精后８５／６小时经热休克处理所孵得的氵蚤状幼体,其四倍体的出现频率约为１９７％。讨论了热休克处理促使第一极体保留生产三倍体和抑制第一次卵裂诱导四倍体的条件和技术关键,以及诱导参数与胚胎发育、胚胎存活的相互关系等问题。     

离体条件下L-色氨酸和吲哚丙酮酸诱导拐芹(Angelica Polymorpha Maxim)根切段直接形成胚状体的初步研究

以拐芹根切段0.5—1cm作为外植体,在MS附加L-色氨酸(L-Trp)2—80mg/L或吲哚丙酮酸(IPA)6—30mg/L和激动素(KT)0.25mg/L的培养基上均可以诱导直接形成胚状体。其中,L-色氨酸的最适浓度为40mg/L,而吲哚丙酮酸的最适浓度为20mg/L。在MS附加吲哚乙酸IAA和激动素KT的培养基上也可以导致体细胞胚胎的直接产生,但频率低于前两者。     

羊草成熟胚诱导愈伤组织及植株再生系统的优化

羊草(Leymus chinensis)为异源四倍体禾本科牧草, 利用成熟胚诱导愈伤组织获得再生植株的效率极低, 难以运用遗传转化方法进行品种改良。我们以羊草成熟胚为外植体, 使用适宜羊草愈伤组织生长的新型培养基配方, 筛选诱导愈伤组织、不定芽分化及生根阶段的最适植物激素浓度、光照和温度条件, 从而优化羊草成熟胚的组织培养方案。研究结果表明, 羊草成熟胚诱导阶段2,4-D的最适浓度为2.0 mg·L ^-1, 变温暗培养, 诱导率可达74.1%; 分化阶段6-BA和NAA的最适浓度均为1.0 mg·L ^-1, 分化率可达57.1%; 生根阶段NAA的最适浓度为0.25 mg·L ^-1, 移栽后成活率为100%。     

用固定化弗劳地柠檬酸杆菌XP05从溶液中回收铂

比较了5种固定弗劳地柠檬酸杆菌XP05菌体的方法,其中明胶海藻酸钠包埋法为固定菌体的最佳方法。扫描电子显微镜观察表明,XP05菌体较均匀地分布于包埋基质中。固定化XP05菌体吸附Pt^4＋受吸附时间、固定化菌体浓度、溶液的pH值和Pt^4＋起始浓度的影响。吸附作用是一个快速的过程;吸附Pt^4＋的最适pH值为1.5;在50～250 mg P^4＋/L范围内,吸附量与Pt^4＋起始浓度成线性关系,吸附过程符合Langmuir和Freundlich吸附等温模型。在Pt^4＋起始浓度250 mg/L、固定化菌体2.0 g/L、pH 1.5和30℃条件下,振荡吸附60 min, 吸附量为35.3 mg/g。0.5 mol/L HCl能使吸附在固定化菌体上的Pt解吸98.7%。从废铂催化剂处理液回收铂的结果表明,在Pt^4＋起始浓度111.8 mg/L、固定化菌体4.0 g/L、pH 1.5和30℃条件下,振荡吸附60 min, 吸附量为20.9 mg/g。在填充床反应器中,在Pt^4＋起始浓度50 mg/L、流速1.2 ml/min、固定化菌体1.86 g的条件下,饱和吸附量达24.7 mg/g; 固定化XP05菌体经4次吸附解吸循环后吸附率仍达78％。     

不同溶液浸泡处理对鹅掌柴扦插繁殖的影响

以清水对照,用多菌灵 福美双溶液和NAA IBA溶液对鹅掌柴插穗浸泡处理后扦插,试验对插穗的形态生长指标和生根过程进行了统计,并对插穗内源性激素IAA、ABA的含量进行了分析。结果表明:NAA IBA和适宜的多菌灵 福美双溶液均可提高插穗的生根率,促进根生长。经浸泡处理的插穗的成活率显著地高于对照(p<0.01)。多菌灵 福美双溶液浸泡插穗3h的理论最佳浓度为519mg/L。519mg/L多菌灵 福美双和200mg/LNAA IBA处理都提高了插穗IAA的含量,ABA的含量却有所降低。用519mg/L多菌灵 福美双和200mg/LNAA IBA分别浸泡插穗1.5h,成活率达到95.6%,比单独用200mg/LNAA IBA处理的成活率提高了10%(p<0.05);实验结果还表明,鹅掌柴的生根属混合生根型。     

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.