三叶虫萤各龄期幼虫形态描述

本文详细描述了三叶虫萤Emeia pseudosauteri各龄期幼虫的外部形态,并初步研究了幼虫的蜕皮过程。三叶虫萤幼虫共8龄,随龄期增大,体色会逐渐加深,体表从3龄开始长出刚毛并逐渐变得硬而尖锐,发光器逐渐变得清晰至突出于体表,臀足着生的多节纤毛逐渐变得长而密,且颜色逐渐变深。幼虫会依附辅助物蜕皮,蜕皮后的幼虫体色由浅粉色逐渐鞣化固定。本文为三叶虫萤的养殖和产业化应用提供了基础数据。     

条背萤幼虫水生适应性形态与游泳行为研究

研究了条背萤Luciolasubstriata幼虫的形态特征及其对游泳行为的适应。形态及扫描电镜观察发现,条背萤幼虫存在二态现象。1～2龄幼虫虫体扁平,多毛。有7对呼吸鳃,分别位于腹部第1～7节。3～6龄幼虫虫体扁平呈船形,无呼吸鳃,靠气管呼吸。二者均具有扁平桨状的足、燕尾状尾节及位于尾节末端的圆柱形粘附器官。条背萤幼虫游动时身体腹面朝上,呈仰泳姿态,足向后划水。3～6龄幼虫仰泳时足共有8种摆动姿势。幼虫仰泳时足摆动1个周期所需时间为(0.611±0.16)s。腹部末端可上下左右摆动,当幼虫向前游动时,尾部上下摆动1个周期所需时间为(1.795±0.44)s。幼虫的游泳速度为(0.85±0.16)mh。仰泳中的幼虫改变方向时,头部和尾部同时向身体的一侧弯曲,当头部与尾部呈近90°时,幼虫用力将尾部伸直,此时水产生一个反作用力继续推动幼虫转向,幼虫转向的范围为0～90°。条背萤2种类型幼虫呼吸系统的不同决定着幼虫外部形态的差异及游泳行为的不同,而导致这种呼吸系统、形态及运动行为不同的原因很可能是条背萤对环境的适应性进化。     

条背萤幼虫不同发育阶段呼吸系统构造的观察和比较

通过显微解剖,结合透射电镜和扫描电镜,观察比较了条背萤Luciola substriata幼虫两个不同发育阶段呼吸系统的差异。结果表明：1～2龄幼虫的呼吸系统中只有气管无气囊,3～6龄幼虫的呼吸系统中气管和气囊并存。1～2龄幼虫的尾气门和3～6龄幼虫的腹部侧气门及尾气门结构没有差异。透射电镜观察提示条背萤1～2龄幼虫体壁上的毛状物为气管鳃。     

条背萤的形态和生物学研究

首次在中国大陆发现水栖萤火虫条背萤Luciola substriata。形态观察发现,条背萤成虫橙黄色, 鞘翅末端灰黑色;发光器均为白色,雄虫发光器位于第5、6腹节,位于第5腹节的发光器呈带状,第6腹节的发光器呈“V”字形;雌虫的发光器呈带状,位于第5腹节;卵椭圆形,橙黄色。幼虫有两种形态,1～2龄具有7对呼吸鳃,3～6龄幼虫无呼吸鳃。幼虫具有一对发光器,位于第7腹节腹面;初蛹期仍保留幼虫形态的发光器,后呈现成虫的发光器,两种形态的发光器并存直至羽化。对条背萤生活史及习性调查发现,条背萤生活在水草较多的池塘、湖泊和流速缓慢的河流中。该虫1年发生1代,以幼虫在水中越冬,5月初老熟幼虫开始上岸化蛹。在25℃下,条背萤预蛹期平均为6.17天,蛹期平均为4.43天。成虫5月上旬至9月中旬发生。日落后的1 h内是条背萤成虫闪光求偶的最盛期。卵期平均12.5天。幼虫的猎物为静水椎实螺Lymnaea stagnalis,凸旋螺Gyraulus conwexiusculus等,天敌为克氏原螯虾Procambarus clarkii、中华绒毛蟹Eriocheir sinensis、草鱼Ctenopharyngodonidellus等。利用光谱仪对条背萤的发光光谱进行测定发现,条背萤的萤光光谱为425～603 nm,峰值为504 nm,颜色为黄绿混合色。     

三叶虫萤的交配与产卵行为

【目的】研究三叶虫萤Emeia pseudosauteri成虫的交配与产卵行为,丰富三叶虫萤的生物学研究,推动三叶虫萤的人工繁育。【方法】采用室内试验与野外观察相结合、仪器拍摄和人工观察相结合的方法研究三叶虫萤的交配与产卵行为。【结果】本文先描述了三叶虫萤成虫交配前雄雄相遇、雌雌相遇、雌雄相遇分别会发生的情况,然后较为详细地描述了交配的过程。交配姿势有上下体位(或称"∠"型)和尾对尾体位(或称"—"型),后者由前者转换而来。雌雄成虫可以多次交配,雄虫有交配干扰和假交配现象。成虫24 h内均有交配现象,交配高峰出现在20:00-22:00(交配率20.8%)和12:00-14:00(交配率15.1%)。雌虫多数喜将卵产在潮湿的苔藓上,卵常聚集成一丛或成簇排列。雌虫可多次产卵,但初次产卵数量最多(高达67.82%),随后产卵量则随产卵次数增加而减少。雌雄虫多次交配后单只雌虫的第一次产卵量[(45±5)粒]多于单次交配后单只雌虫第一次产卵量[(20±4)粒]。雌虫的产卵次数和产卵量与其体重相关,体重越重则其产卵次数和产卵量越多。【结论】三叶虫萤的交配产卵行为与以往报道的萤火虫交配产卵行为很多相似之处,但也有一些特殊行为或规律。     

叶色草蛉的生物学研究Ⅱ.种群干扰和搜索行为(英文)

研究了叶色草蛉对棉蚜的搜索行为及其自身的种群干扰行为。结果表明:1)在两处地点的4种试验容器即培养皿、养虫器、内置障碍物的养虫器和内置盆栽棉花的笼罩中,草蛉幼虫的捕食效率因猎物的密度而变化。其捕食常数(Q)和干扰系数(m)随密度的增加而增大,但随空间异质性的增加而减小;2)在笼罩的棉株上,一龄和二龄草蛉幼虫每天的食蚜量分别为13.6头和29.4头。幼虫较多地在上部叶片上捕食棉蚜;3)在笼罩的棉株上,无论是一龄幼虫还是二龄幼虫草蛉都更多地停留在下部的棉叶上,且在上部叶片和下部叶片上的草蛉幼虫的百分率存在明显差异     

不同温度对三叶虫萤卵孵化和初孵幼虫发育的影响

本文研究了三叶虫萤Emeia pseudosauteri在不同恒温设置和室内变温条件下卵孵化率和初孵幼虫存活率,并通过直接最优法和直线回归法计算出了三叶虫萤卵的发育起点温度和有效积温。结果表明:12~30℃恒温条件下,卵的孵化率随着温度升高显著下降(P<0.05),且均低于室内变温条件(P<0.05)下的孵化率;初孵幼虫在恒温15℃下的存活率最高,为73.13%;低于12℃和高于30℃恒温中初孵幼虫均无法存活;在恒温条件12~30℃下,卵的发育历期随温度升高而缩短,其中恒温12℃下最长,发育历期为42.96 d(n=3),恒温30℃下最短,发育历期仅12.75 d(n=3)。通过直接最优法计算出三叶虫萤卵的发育起点温度为3.52℃,有效积温分别为382.20 d·℃。上述结果为三叶虫萤的人工繁育提供了参考。     

黄玛草蛉对木瓜粉蚧的捕食作用评价

为明确黄玛草蛉Mallada basalis(Walker)对木瓜粉蚧Paracoccus marginatus Williams and Granara de Willink的捕食作用,在实验室条件下观察了黄玛草蛉2龄、3龄幼虫对木瓜粉蚧2龄、3龄若虫及成虫的捕食选择偏好,同时采用捕食功能反应方法评价了黄玛草蛉2龄、3龄幼虫对木瓜粉蚧各虫态的捕食效能.结果表明,黄玛草蛉2龄、3龄幼虫偏好捕食木瓜粉蚧若虫,对木瓜粉蚧各虫态的捕食量均随着猎物密度的增加而增加符合HollingⅡ模型.其中,黄玛草蛉3龄幼虫具有较高的捕食能力,其对木瓜粉蚧2龄、3龄若虫及成虫的日最大捕食量分别为116头、81头和19头,a/Th值(a为瞬时攻击率,Th为处置单头猎物时间)分别为284.76、134.26和28.38.黄玛草蛉幼虫对猎物的寻找效应随猎物密度的增加而呈线性下降,且在相同猎物密度条件下,黄玛草蛉3龄幼虫对猎物的搜寻效应明显高于2龄幼虫.研究结果表明,黄玛草蛉对木瓜粉蚧具有较好的捕食能力.     

幼虫密度对草地螟食物利用率及消化酶活性的影响

为了阐明草地螟Loxostege sticticalis大发生种群幼虫取食行为特征, 在室内条件下（温度22±1℃, 相对湿度70%）对不同幼虫密度［1, 10, 30头/瓶（650 mL）］饲养草地螟幼虫的食物利用率及消化酶活性进行了研究。结果表明： 幼虫中等（或高）密度对草地螟幼虫相对中肠重量、 相对取食量、 粪便干重、 食物利用率和近似消化率及总蛋白酶和亮氨酸氨肽酶活性影响显著。幼虫相对中肠重量以10头/瓶的幼虫密度最大, 1头/瓶的幼虫密度最小。随着幼虫密度的增加, 幼虫相对取食量和粪便干重增加, 而虫体干重减轻, 幼虫食物利用率降低。幼虫密度30头/瓶的幼虫相对取食量和粪便干重显著高于1和10头/瓶的, 而30头/瓶的幼虫食物利用率显著低于1头/瓶的。幼虫近似消化率随幼虫密度的逐渐增加而显著降低。幼虫密度10头/瓶的幼虫总蛋白酶和亮氨酸氨肽酶的活性显著高于1和30头/瓶的, 而淀粉酶的活性受幼虫密度影响不显著。随幼虫密度的增加, 幼虫相对中肠重量与总蛋白酶和亮氨酸氨肽酶活性变化趋势较为一致, 消化酶活性的变化可能与相对中肠重量大小有关。因此, 幼虫密度是影响草地螟幼虫取食行为的重要因子, 这些结果为阐明草地螟大发生种群与一般种群的为害特征提供了重要理论依据。     

Effects of larval density on food utilization efficiency and digestive enzyme activity of the beet webworm, Loxostege sticticalis (Lepidoptera: Pyralidae)

为了阐明草地螟Loxostege sticticalis大发生种群幼虫取食行为特征,在室内条件下(温度22±1℃,相对湿度70％)对不同幼虫密度[1,10,30头/瓶(650 mL)]饲养草地螟幼虫的食物利用率及消化酶活性进行了研究.结果表明:幼虫中等(或高)密度对草地螟幼虫相对中肠重量、相对取食量、粪便干重、食物利用率和近似消化率及总蛋白酶和亮氨酸氨肽酶活性影响显著.幼虫相对中肠重量以10头/瓶的幼虫密度最大,1头/瓶的幼虫密度最小.随着幼虫密度的增加,幼虫相对取食量和粪便干重增加,而虫体干重减轻,幼虫食物利用率降低.幼虫密度30头/瓶的幼虫相对取食量和粪便干重显著高于1和10头/瓶的,而30头/瓶的幼虫食物利用率显著低于1头/瓶的.幼虫近似消化率随幼虫密度的逐渐增加而显著降低.幼虫密度10头/瓶的幼虫总蛋白酶和亮氨酸氨肽酶的活性显著高于1和30头/瓶的,而淀粉酶的活性受幼虫密度影响不显著.随幼虫密度的增加,幼虫相对中肠重量与总蛋白酶和亮氨酸氨肽酶活性变化趋势较为一致,消化酶活性的变化可能与相对中肠重量大小有关.因此,幼虫密度是影响草地螟幼虫取食行为的重要因子,这些结果为阐明草地螟大发生种群与一般种群的为害特征提供了重要理论依据.     

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.