异色瓢虫成虫耐寒能力的季节性变化

为研究异色瓢虫Harmonia axyridis自然种群耐寒能力的季节性变化,测定了其过冷却点、体内含水量及总脂肪含量和低温存活力。结果表明：异色瓢虫成虫低温存活力呈现出明显的季节性变化,越冬前成虫的耐寒性显著强于夏季成虫和越冬后成虫。冷驯化（5℃, 5 d）可以显著提高夏季成虫的低温存活力。雌雄成虫过冷却点和体内含水量随气温的降低而降低,升高而升高。过冷却点7月份最高,分别为−7.6℃和−8.0℃;越冬中期（2008-01-15）最低,分别为−18.1℃ 和−16.9℃。雌雄成虫体内含水量9月份最高,分别为66.87%和68.01%,10月份显著降低,越冬后期（2008-02-19）最低,分别为52.94%和51.53%。越冬期间过冷却点和体内含水量显著低于其他时期。而雌雄成虫体内总脂肪含量在越冬开始就达到最高,分别为50.07%和47.93%,随后又逐渐降低,越冬期间显著高于其他时期。由此可知异色瓢虫自然种群的耐寒性呈现出明显的季节性变化,文中还就异色瓢虫自然种群耐寒性影响因素及其越冬策略进行了讨论。     

不同冷藏条件对食蚜瘿蚊过冷却点和冰点的影响

【目的】食蚜瘿蚊Aphidoletes aphidimyza(Rondani)是一种捕食性天敌,其幼虫对蚜虫具有较好的控制潜能。研究不同冷藏条件对食蚜瘿蚊耐寒能力的影响,为食蚜瘿蚊的低温冷藏技术提供了理论依据。【方法】利用热电偶原理,测定食蚜瘿蚊在不同冷藏条件下的过冷却点和结冰点。【结果】25℃条件下,食蚜瘿蚊各虫态的过冷却点及结冰点存在显著差异（P<0.05）,其中2龄幼虫过冷却点（﹣26.18℃）和结冰点（﹣24.98℃）最低,雄成虫过冷却点（﹣22.95℃）和结冰点（﹣21.86℃）最高。在不同变温条件下冷藏食蚜瘿蚊蛹,其过冷却点在冷藏10、20和30 d时均上升且高于对照,冷藏40 d时低于对照;同一冷藏时长下不同冷藏方式间过冷却点的差异均不显著（P>0.05）。食蚜瘿蚊蛹在5℃条件下冷藏50d,每天定时7℃中断4h的结冰点（﹣23.09℃）最低,冷藏30d的结冰点（﹣21.15℃）最高;食蚜瘿蚊蛹在5℃条件下冷藏40 d,每天定时9℃中断4 h的结冰点（﹣22.66℃）最低,冷藏20 d时的结冰点（﹣20.95℃）最高;同一冷藏时长下3种冷藏方式间结冰点差异均不显著（P>0.05）。【结论】食蚜瘿蚊2龄幼虫的耐寒能力最强,雌成虫的耐寒能力要高于雄成虫;变温贮存和恒定低温均适合食蚜瘿蚊的低温贮存。     

光周期对中华通草蛉自然越冬成虫及实验种群幼虫耐寒能力的影响

【目的】滞育诱导期进行短光照处理可影响昆虫耐寒性。为明确光周期对中华通草蛉Chrysoperla sinica (Tjeder)耐寒性的影响, 针对中华通草蛉滞育解除过程及非滞育虫态的耐寒性进行了一系列研究。【方法】测定了中华通草蛉自然越冬成虫的过冷却点（supercooling point, SCP）以及长光周期（15L∶9D）和短光周期（9L∶15D）条件下自然越冬成虫在滞育解除过程中在-12℃下的死亡率, 并测定了室内长、 短两种光周期下实验种群2龄和3龄幼虫的过冷却点（SCP）、 结冰点（freezing point, FP）以及-7℃下的死亡率。【结果】中华通草蛉12月份的自然越冬成虫SCP集中在-10~-14℃之间。SCP低于-12℃的个体占43.70%, 且-12℃处理1 d死亡率为62.00%。-12℃处理1 d条件下的长、 短光周期处理自然越冬成虫, 除处理0 d外, 长光周期处理死亡率均高于短光周期处理的, 且在处理15 （P=0.012）, 20 （P=0.01）和25 d （P=0.001）差异显著。中华通草蛉试验种群相同龄期幼虫在短光周期下的SCP和FP均高于长光周期下, 但差异不显著(P>0.05); 但在-7℃下, 2龄幼虫短光周期下的低温死亡率为67.00%±4.04%, 显著低于长光周期下的低温死亡率（78.00%±1.33%）（P=0.011）, 3龄幼虫短光周期条件下低温死亡率为24.33%±1.33%, 显著低于长光周期下的低温死亡率（53.00%±3.46%）（P=0.002）。【结论】中华通草蛉为结冰敏感型, 诱导滞育的短光照处理可提高其幼虫期及滞育解除过程中成虫的耐寒能力。     

异色瓢虫越冬聚集行为对其能量代谢的影响

异色瓢虫以成虫滞育越冬,越冬期间聚集行为尤为显著。为探讨异色瓢虫越冬聚集行为的适应意义,本研究利用便携式红外线CO2分析仪测定了6 种聚集度（分别用1头、2头、5头、10 头、20头和50头表示）下异色瓢虫越冬成虫的呼吸量,并通过呼吸量计算得到各聚集度下的呼吸速率（Respiration rate, Rr）和能量代谢速率（Metabolism rate, Rm）。结果表明: 不同聚集度间异色瓢虫越冬成虫的呼吸速率和能量代谢速率均存在显著性差异,相关性分析表明Rr和Rm值与聚集度之间呈显著负相关。即随着聚集度的增加,越冬成虫的呼吸速率和能量代谢速率呈逐渐降低的趋势。此外,利用“Y”形嗅觉仪测定了异色瓢虫实验种群和越冬种群成虫对不同味源的选择趋性,表明异色瓢虫均对各自的群体表现出趋性,而其越冬聚集行为的发生需要一种特殊的气味物质。本研究表明聚集行为可以有效降低异色瓢虫的新陈代谢速率,减少能量消耗,有利于其种群成功越冬,这对其越冬来说具有非常重要的意义。     

异色瓢虫成虫冷驯化反应及体内几种酶活力的相关变化

为明确冷驯化反应对异色瓢虫Harmonia axyridis (Pallas) 实验种群成虫耐寒性及其生殖能力的影响, 本研究测定了成虫低温存活率、过冷却点(supercooling point, SCP)、体内含水量及雌虫繁殖能力等。结果表明: 冷驯化（在5℃下诱导3 d, 5 d）后, 成虫再在-5℃下暴露3 d的存活率由对照（预先未进行冷驯化）的46%分别提高至60%和67%, 而诱导10 d后的存活率(51%)反而下降。冷驯化效应在其成虫转移至饲养条件下7 d后就消失。随着低温诱导时间的延长过冷却点及体内含水量均呈现下降趋势, 短时间(5, 10 d)的诱导不能使成虫的SCP明显降低, 但可以使含水量极显著下降。冷驯化后异色瓢虫雌虫产卵前期延长; 虽然冷驯化对雌虫首次产卵量没有影响, 但是随着诱导时间的延长连续观察72 h内单头雌虫累计产卵量却降低。冷驯化过程中成虫体内几种酶活力的检测结果表明: 两种细胞保护酶超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性升高, 与新陈代谢有关的乳酸脱氢酶(LDH)及Na⁺, K⁺-ATP酶活性却降低。结果显示, 低温胁迫前异色瓢虫成虫经过不同时间的诱导后有可能提高其低温抵抗能力, 而且冷驯化诱导成虫耐寒性增加是一种复杂的生理生化过程, 这一过程对其生存和繁殖具有重要的适应意义。     

温湿度对越冬异色瓢虫(Harmonia axyridis)存活的影响

为了明确温度和相对湿度对越冬异色瓢虫存活的影响,采用二次正交旋转组合设计,试验了秋冬季收集的异色瓢虫自然种群在不同温湿度组合下,经不同时间后的存活率和存活时间。结果表明,在试验条件下最佳温湿度组合为０℃,ＲＨ７５％。此条件下处理６个月以上时存活率仍达８０％以上,存活时间近９ｄ;温度对异色瓢虫的存活影响最大,湿度次之,温湿度的交互作用最不重要;由试验结果建立了不同处理时间下,温湿度与存活率和存活时间之间关系的一系列二次回归方程。对方程分析表明：０～４℃为异色瓢虫越冬的适宜温度,小于０℃的低温引起存活率下降和存活时间缩短,ＲＨ７０％～８０％为异色瓢虫越冬的适宜湿度,低于ＲＨ６０％和高于ＲＨ９０％不利于存活;处理后的异色瓢虫的存活率和存活时间随着处理时间的延长而减小。但处理时间为６个月以内时,存活率的下降幅度较小     

异色瓢虫(Harmonia axyridis)鞘翅色斑二个新等位基因和嵌镶显性遗传学说的再证实

异色瓢虫是一个鞘翅色斑表现多态的亚洲物种。但在苏联西伯利亚中西部阿尔泰地区群体几乎单一地由黑底小黄斑的花斑型axyridis(S~x)所组成,在我国东北黑龙江几乎全为黄色或黄底带有不同数目小黑点的黄底型Succinea(ss)所组成,由北向南黄底型的百分比逐渐减小,增添了黑底大黄斑类型。因此,常见的有三型:由浅色的黄底型和深色的四窗型Spectabilis(S~s)和二窗型conspicua(S~c)所组成,越向南深色类型越趋增多。鞘翅色斑各型的频率,在其广大的分布区内有着地理性的变化,但各局部地区亦有相对稳定的一定的频率,标志着该局部地区的群体的特征(Tan,1932;Dobzhansky 1951)。除上述空间的变化外,也存在着季节性的变化等(Mayr,1963;Tan,1948)。群体中除上述三种基本类型外,尚有罕见类型,各罕见类型也以一定的低频率而出现,     

灰飞虱长、短翅型品系对高、低温的适应能力差异

【目的】灰飞虱Laodelphax striatellus种群存在长翅和短翅个体,其翅型分化受遗传和环境条件的影响。本研究旨在明确经连续定向选育的灰飞虱长、短翅型品系对高、低温的适应能力差异。【方法】在室内分别长期定向筛选63和65代建立灰飞虱长、短翅型品系,并在南京田间采集灰飞虱自然种群;分别在25℃, 30℃和35℃恒温条件下测定上述灰飞虱长、短翅型品系和自然种群的繁殖力、存活率和发育历期,测定若虫在5℃和-20℃下的存活率以及若虫和成虫的过冷却点,通过品系间存活率、发育历期、生殖力和过冷却点的比较分析,确定灰飞虱长、短翅型品系对高温和低温的耐受能力。【结果】在25℃, 30℃和35℃下,灰飞虱自然种群雌成虫的繁殖力均显著高于室内筛选后的长、短翅型品系,而长、短翅型品系雌成虫之间的繁殖力均无显著差异;长、短翅型品系的繁殖力在25℃和30℃之间均无显著差异,但自然种群在25℃下的繁殖力显著高于30℃条件下的繁殖力;35℃下长、短翅型品系基本无若虫产生。25℃下长翅型品系、短翅型品系和自然种群若虫的存活率无显著差异,但在30℃下,短翅型品系若虫的存活率显著低于自然种群,而与长翅型品系差异不显著;35℃下长、短翅型品系的若虫最长只能存活到3龄,且两品系间无显著差异,而自然种群可存活到5龄。25℃下,短翅型品系若虫的发育历期显著短于自然种群,而与长翅型品系无差异;但是在30℃下,短翅型品系若虫历期显著长于长翅型品系和自然种群。长翅型品系、短翅型品系和自然种群灰飞虱3-4龄若虫在5℃低温下的存活天数无显著差异,并且长翅和短翅型品系在-20℃极端低温下暴露10 min后其死亡率也无显著差异且均显著高于自然种群。3个品系(种群)成虫的过冷却点无显著差异,但5龄若虫的过冷却点表现为短翅型品系显著高于自然种群,而与长翅型品系无显著差异。【结论】经连续定向选育的灰飞虱长、短翅型品系对低温和高温的适应力基本相当,且低于自然种群。在高温条件下灰飞虱短翅型品系的发育速率低于长翅型品系。     

异色瓢虫Harmonia axyridis“单生雌”异常性比的母系遗传

前言 异色瓢虫是一种分布在亚洲的鞘翅色斑类型表现多态现象的物种。根据谈家桢等的早期工作,色斑类型可分为黄底型和黑底型两大系统。不同类型的杂交试验证明,它们是由一个单个基因的一系列复等位基因所决定,杂交子代按孟德尔式规律遗传,黑色部分为显性,黄色部分为隐性,所以双亲的黑色部分均能在杂交子代的同一个体上显     

吡虫啉对异色瓢虫种群控害功能的影响

【目的】杀虫剂对天敌的非致死效应是杀虫剂安全性评估的重要内容。【方法】本研究以吡虫啉亚致死浓度处理的大豆蚜Aphis glycines饲喂异色瓢虫Harmonia axyridis,测定了异色瓢虫的发育历期、存活率、蛹重和捕食功能反应。【结果】异色瓢虫G0代不论从哪个龄期开始饲喂毒蚜,LC25(W)处理各龄期其发育均显著延长,且未成熟期(1龄至成虫)显著延长,蛹重和存活率显著降低;异色瓢虫G0代从1龄、3龄和4龄开始饲喂毒蚜,显著延长G1代的3龄龄期,显著缩短G1代的4龄龄期;G0代从4龄开始饲喂毒蚜,显著延长G1代1-3龄的发育历期;G0代不论从哪个龄期开始饲喂毒蚜,G1代蛹重都显著降低,G1代幼虫存活率无显著的变化;异色瓢虫对LC25处理的2龄、3龄和4龄幼虫的最大捕食量显著降低,其余组无显著变化。【结论】吡虫啉亚致死浓度对异色瓢虫G0代和G1代的生长发育均产生影响,且影响异色瓢虫的捕食能力,从而影响异色瓢虫种群的控害功能,这种杀虫剂对非靶标天敌昆虫的非致死效应需要在杀虫剂的安全性评估中予以考虑。     

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.