黄姑鱼三倍体的诱导、鉴定及其性腺发育特征

研究采用冷休克方法诱导黄姑鱼(Nibea albiflora)三倍体并进行鉴定,进一步采用组织学和生殖相关基因表达分析比较了三倍体黄姑鱼的性腺发育特征。研究结果表明:(1)在受精后2.5min以3℃进行10min的冷休克处理,冷休克处理组的受精率和孵化率分别为(70.31±4.49)%和(21.5±6.63)%,其受精率和孵化率显著低于二倍体对照组;(2)经流式细胞仪倍性检测和染色体核型分析发现,三倍体的DNA含量为二倍体的1.5倍,染色体数目为72条,而二倍体的染色体数目为48条,三倍体的比例为100%;(3)三倍体的生殖腺指数显著低于二倍体,进一步通过组织切片观察发现三倍体的精巢和卵巢发育较二倍体滞后,在12月龄时,二倍体精巢和卵巢处于Ⅴ期,而三倍体精巢和卵巢分别处于Ⅲ期和Ⅰ期;(4)三倍体精巢的dmrt1和vasa基因及三倍体卵巢的cyp19a基因表达量均显著低于二倍体(P<0.05);三倍体卵巢的vasa基因表达量也比二倍体低(P>0.05)。综上结果表明:研究通过冷休克处理成功诱导了黄姑鱼三倍体;三倍体的性腺发育较二倍体滞后,育性明显降低。     

斑鳢、乌鳢及其杂种细胞核DNA流式含量分析

以斑鳢(Channa maculata)、乌鳢(C.argus)及其正交杂种斑乌鳢(斑鳢♀×乌鳢♂)和反交杂种乌斑鳢(乌鳢♀×斑鳢♂)的红细胞为材料,以鸡(Gallus gallus)血细胞为DNA标准(2.5 pg/2c,2c指2倍体),采用流式细胞仪测定了这4种鱼的细胞核DNA含量。斑鳢、乌鳢、斑乌鳢及乌斑鳢这4种鱼血细胞DNA的绝对含量分别为(1.488±0.035)pg/2c、(1.489±0.034)pg/2c、(1.522±0.077)pg/2c和(1.520±0.033)pg/2c。斑鳢和乌鳢的细胞核DNA含量差异不显著(P0.05),斑鳢和乌鳢与两种杂交鳢的DNA含量差异显著(P0.05),两种杂交鳢之间的细胞核DNA含量差异不显著(P0.05)。杂交鳢细胞核DNA含量显著高于亲本,可以作为杂种鉴定的依据。     

人工诱导兴国红鲤三倍体最佳诱导条件的研究

采用冷休克处理兴国红鲤受精卵诱导产生三倍体鱼 ,初步探讨了获得三倍体兴国红鲤的最佳诱导条件 ,即最恰当的诱导温度 ,最恰当的诱导起始时间 ,最恰当的冷休克处理时间。结果表明 ,在人工授精后 5～ 8min ,将受精卵置于 0～ 2℃的冰水中冷休克处理 1 0～ 1 5min ,再迅速回温至正常水温 ( 2 0～ 2 5℃ )的水中发育 ,可以获得 ( 70± 5) %的三倍体兴国红鲤胚胎 ,孵化率为 50 %～ 70 % ,成活率可达 4 0 %～50 %以上 ,此为采用冷休克技术人工诱导兴国红鲤三倍体的最佳条件。     

三个鲫品系DNA含量的比较研究

采用流式细胞术 (FCM)对红鲫、彭泽鲫、异育银鲫进行红血球DNA含量的检测分析比较 ,以鉴定它们的倍性。结果显示 ,红鲫红血球的DNA含量是 3 0pg ,彭泽鲫是 4 7pg ,异育银鲫是 4 8pg。显而易见 ,彭泽鲫的DNA含量是二倍体红鲫的 1 57倍 ,异育银鲫的DNA含量是红鲫的 1 6倍。采用肾细胞直接制作染色体的方法进行红鲫、彭泽鲫、异育银鲫的染色体倍性鉴定 ,结果红鲫的染色体数目是 10 0 ,为二倍体 (2n =10 0 ) ,彭泽鲫的染色体数目是 162 ,为三倍体 (3n =162 ) ,异育银鲫的染色体数目是 156— 162 ,为三倍体 (3n =156— 162 )。研究证明 :不同品系鲫的DNA含量高低与染色体的倍性有显著的正相关性     

白鲫（♀）×红鲫（♂）异源四倍体鱼的倍性操作及其生殖力的研究

采用热休克调控技术诱导出103尾第一代白鲫（♀）×红鲫（）异源四倍体鱼,并对其生殖力进行了研究。1或2龄的四倍体雄鱼能产生精子,而雌鱼不能产生正常的卵。将异源四倍体雄鱼与二倍体白鲫雌鱼交配产生倍间三倍体鱼,染色体检查证明是整三倍体（3N＝150）,但其受精率很低（11．4—51．3％,平均32．4％）．网箱养殖结果表明,倍间三倍体白鲫的生长速度比白鲫快30％以上,雌雄均不育．并用冷休克处理回收异源四倍体4N（）×白鲫2N（♀）受精卵的第二极体产生了新的四倍体鱼．文中还对第一代异源四倍体鱼的批量生产、生殖能力以及异源三倍体鱼的生产应用进行了讨论．     

橡胶树四倍体来源鉴定及不同倍性叶片解剖结构比较

利用25对SSR引物,采用基于PCR的毛细管电泳法鉴定14株人工诱导四倍体的来源,并采用2种切片方法比较橡胶树不同倍性叶片的厚度差异。结果表明,14株四倍体中9株为同一无性系,另有5株为同一无性系或全同胞子代,14株四倍体的同源二倍体的亲本之一为热研73397。橡胶树二、三、四倍体间的叶片、上表皮、栅栏组织、海绵组织的厚度差异极显著(P0.01),且随着倍性的增加而增加。二、三、四倍体鲜叶厚度分别为159.98±16.04μm、188.52±16.29μm、204.21±16.45μm,叶片石蜡切片厚度分别为139.94±13.22μm、169.53±15.07μm、180.84±26.71μm。以鲜叶厚度177.81μm或石蜡切片厚度160.70μm为临界值可以区分人工体细胞诱导四倍体橡胶树获得的二、四倍混合群体中的二倍体和四倍体。不同倍性的叶片结构紧密度和栅海比大小排序均为:三倍体四倍体二倍体,叶片结构疏松度大小排序为:二倍体四倍体三倍体。本研究结果为橡胶树多倍体资源的鉴定和多倍体育种策略选择提供了参考。     

三倍体九孔鲍生物学特性的初步探讨

采用细胞松弛素B(Cytochalasin B)抑制九孔鲍受精卵第二极体的释放获得三倍体材料,进行三倍体与普通二倍体的生长对比试验,试验分为仔鲍和成鲍两个养殖阶段。观察了三倍体性比和性腺发育情况。结果表明,三倍体九孔鲍比普通二倍体九孔鲍具有显著的生长优势。投放的担轮幼虫经5个月培育,三倍体平均壳长可达2.25cm,壳长绝对生长量是普通二倍体的1.20倍;平均壳长3.25cm的个体经6个月培育后壳长为5.43cm,绝对增长量是普通二倍体的1.80倍。三倍体成鲍性比和二倍体没有显著差异,接近1:1;三倍体性腺发育程度较低,雌、雄性腺大小和体积比例均明显小于同期培育的二倍体成鲍。     

用流式细胞仪检测大黄鱼三倍体

通过对大黄鱼二倍体和三倍体的倍性分析,建立流式细胞仪检测三倍体的方法。大黄鱼受精卵经三倍体诱导处理后,胚胎期进行染色体滴片证实在处理组中有三倍体细胞存在。接着对该组胚胎进行育苗,获得1￣3cm的鱼苗,用流式细胞仪进行检测。以二倍体大黄鱼的肌肉组织或血液细胞DNA含量的峰值道数作为对照,用同样的方法取样处理、上机、测定处理组样本个体细胞的DNA含量的峰值道数。如果处理组个体细胞的DNA含量的峰值道数是二倍体组的1.5±0.1倍,则认为该个体为三倍体。实验结果经冷休克或静水压诱导处理的样本共检测182个,三倍体检出率为12.09%,其中有一组检出率高达55.56%。     

人工诱导泥鳅雌核发育的细胞学研究和诱导参数优化

为培育泥鳅(Misgurnus anguillicaudatus)全雌品种,研究通过细胞荧光染色后进行细胞学观察确定人工诱导泥鳅雌核发育的热休克起始时间,并进一步利用核型和流式细胞分析等方法对人工诱导雌核发育泥鳅进行鉴定。结果显示,二倍体泥鳅受到灭活的鲤(Cyprinus carpio)精子刺激后,第二极体与卵核分开的时间在人工授精后3—5min;卵子在人工授精后3.5min后再热休克2min的诱导孵化率达到10.26%。通过分析野生型泥鳅胚胎、人工诱导雌核发育泥鳅胚胎、泥鳅×鲤杂交胚胎和单倍体泥鳅胚胎的发育,发现部分雌核发育的胚胎可以正常发育,而杂交胚胎和单倍体胚胎会出现明显的发育障碍。核型和流式细胞检测分析表明利用本研究获得的热休克参数进行处理可得到二倍体雌核发育子代,二倍率达64.71%。研究从细胞学层面获得泥鳅雌核发育的诱导参数,可为利用人工诱导雌核发育开展全雌泥鳅育种提供指导。     

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。     

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.