内蒙古典型草原区狭颅田鼠集群数量与被捕食风险的关系

2005年9月15日—30日,在内蒙古锡林郭勒盟西乌珠穆沁旗的典型草原上研究了狭颅田鼠(Microtus gregalis)冬季集群与来自艾虎(Mustela eversmanni)的捕食风险。采用鼠洞口数量作为狭颅田鼠集群大小的指标,分析了艾虎对不同大小狭颅田鼠集群的捕食优先选择偏好。对实验样地内狭颅田鼠的洞群洞口数进行了调查统计(样地内总共涉及102个狭颅田鼠有效洞群),并计数此期间的艾虎粪便堆数以及攻击掘开狭颅田鼠洞群的情况。运用非参数的Mann-Whitney U检验法进行数据分析,结果表明:从艾虎遗留的粪便痕迹来看,没有被艾虎访问过的田鼠洞群与被艾虎访问过的洞群之间差异达到极显著水平;另外,从狭颅田鼠洞口被艾虎掘开的痕迹来分析,没有被艾虎挖掘的洞群与被艾虎挖掘的洞群之间的差异也达到极显著的水平;另外,随着田鼠洞群洞口数量的增加,出现艾虎粪便和掘洞的频次和概率就越高。表明艾虎对狭颅田鼠集群洞口数的选择差异性非常显著,明显倾向于选择在洞口数量多的狭颅田鼠洞群停留,同时也更倾向于掘开洞口数量较高的狭颅田鼠洞群作为捕食对象。     

大■对不同数量布氏田鼠越冬洞群的选择偏好

2004年10月2~7日在内蒙古东乌珠穆沁旗额和宝力格苏木鼠害草场采用鼠洞口数量作为布氏田鼠(Lasiopodomys brandtii)秋季集群大小的指标,分析了大■(Buteo hemilasius)对不同大小布氏田鼠集群的捕食选择偏好。统计了实验样地内可以观察到的大■蹲守布氏田鼠洞群鼠洞口数量,以及样地内大■没有蹲守的布氏田鼠洞群的鼠洞口数量。运用非参数Mann-Whitney U检验进行分析,大■没有蹲守的布氏田鼠洞群的洞口数量秩和统计量为1 753.5,而大■蹲守的布氏田鼠洞群的洞口数量总秩和为1 406.5,统计量U值为213.5,校正之后的Z值为﹣4.764 26,这表明,两组差异达到极显著水平(P=0.000 002),大■蹲守次数(B)与田鼠洞群洞口数量(N)呈显著的正相关关系,相关式为B=﹣0.733 2+0.044 36 N(r=0.592 65,P0.05)。结果表明,大■优先选择集群数量高的布氏田鼠集群,该结果可以解释布氏田鼠在秋季出现的分群行为。由于捕食风险的存在,布氏田鼠借助秋季的分群行为以降低冬季集群大小和被捕食风险,从而避免成为捕食性天敌首要攻击的目标,该结果从捕食风险角度支持了鼠类最优集群理论。     

布氏田鼠秋季家群数量与捕食风险的关系

2004年9月25日至10月15日,在内蒙古锡林郭勒盟阿巴嘎旗白音图嘎苏木研究了布氏田鼠(Lasiopodomys brandtii)秋季家群数量与来自艾虎(Mustela eversmanni)的捕食风险。布氏田鼠家群数量调查采用标志重捕法和最小已知存活数估计法(即MNA法)确定,而艾虎对布氏田鼠捕食风险的衡量指标采用在研究期间布氏田鼠洞群区新出现的艾虎粪便和挖掘痕迹。研究区面积4 hm2,涉及91个布氏田鼠家群,658只布氏田鼠,其中,17个布氏田鼠家群有新出现的艾虎粪便,5个家群被艾虎掘开。运用非参数的Mann-Whitney U检验进行数据分析,从艾虎遗留的粪便痕迹来看,未出现艾虎粪便的布氏田鼠家群总秩和为1 096,出现艾虎粪便的田鼠洞群秩和为3 090,统计量U=315,校正Z=﹣3.241,校正P=0.001 2;另外,从艾虎掘开的田鼠家群来分析,没有被艾虎挖掘的布氏田鼠家群秩和为3 757,而被艾虎掘开的田鼠家群秩和为429,统计量U=16,校正Z值为﹣3.514,P=0.000 4。两组差异达到极显著水平,表明艾虎对秋季高数量的布氏田鼠家群具有显著的优先访问和攻击偏好,也意味着高数量的布氏田鼠秋季家群具有更高的被艾虎捕食的风险。     

大鵟对不同数量布氏田鼠越冬洞群的选择偏好

布氏田鼠(Lasiopodomys brandtii)在冬季会形成数量不同的越冬集群,不同大小的集群会面临着不同的捕食风险。2004年秋季在内蒙古锡林郭勒盟典型鼠害草场,采用鼠洞口数量多少作为布氏田鼠秋季集群大小的指标,分析了大鵟(Buteo hemilasius)对不同大小集群的布氏田鼠集群的捕食选择偏好。结果表明：大鵟优先选择集群数量高的布氏田鼠集群,这表明数量高的布氏田鼠集群更容易吸引猛禽类天敌的捕食,该结果可以解释布氏田鼠在秋季出现的分群行为。由于捕食风险的存在,布氏田鼠借助秋季的分群行为以降低冬季集群大小和被捕食风险,从而避免成为捕食性天敌首要攻击的目标,该结果验证了最优集群理论。     

大鵟对长爪沙鼠秋季的集群捕食策略

2003年9月10日—15日,在内蒙古东乌珠穆沁旗嘎达布其口岸附近的典型草原区鼠害草场研究了大鵟(Buteo hemilasius)对长爪沙鼠的捕食策略。鉴于秋季是长爪沙鼠的活跃期,直接采用鼠丘核心区的沙鼠洞口数作为衡量长爪沙鼠集群大小的指标,分析了大鵟对不同大小集群的长爪沙鼠家族集群的捕食选择偏好。实验涉及了3hm2的实验样地,样地中具有符合实验统计的长爪沙鼠洞群为87个。5d内作者观察到大鵟蹲守在样地中的长爪沙鼠29只次,共涉及23个沙鼠洞群。通过分析大鵟蹲守和没有蹲守过的沙鼠洞群的洞口数量,利用非参数的Mann-Whitney U检验法分析,结果表明:大鵟蹲守的洞群的洞口数量总秩和为2569.5,大鵟没有蹲守的沙鼠洞群的洞口数量秩和统计量为1258.5,统计量U值为489.5。校正之后的Z值为-2.37459,两组差异达到显著的水平(P=0.017574)。此外,分析还显示:沙鼠洞群洞口数量(S)与大鵟蹲守次数(F)呈显著的正相关关系,相关式为:F=-0.0559+0.023×S,(r=0.2707,P﹤0.05)。结果表明,大鵟会首先在洞口数量多的长爪沙鼠集群蹲守捕食,因此在越冬期间,长爪沙鼠的集群数量会被限制,进而可能形成一种最优化集群数量的模式。本文的研究结果从一定角度支持了鼠类通过形成最优集群以降低天敌捕食概率的理论。长爪沙鼠可能借助扩散行为,以及秋季的分群行为来降低集群密度从而降低被捕食风险。     

高寒草甸生态系统中高原鼠兔和高原鼢鼠的捕食风险及生存对策

调查青藏高原高寒草甸生态系统中两种主要啮齿动物及其天敌动物的种群密度,分析天敌动物对两种啮齿类的捕食方式、捕食强度,探讨啮齿类动物的捕食风险及生存对策。研究结果表明,高原鼠兔和高原鼢鼠的种群密度分别为4．97只／hm^2和10．6只／hm^2,而它们的主要天敌赤狐、艾虎和香鼬的种群密度分别为0．16只／100hm^2、0．37只／100hm^2、3只／100hm^2。艾虎和香鼬在取食过程中主要搜寻啮齿类的洞道系统,全部食物几乎都来源于洞道系统内;赤狐或取食地面活动的鼠兔,或挖掘洞口待高原鼢鼠封闭洞口时取食猎物。高原鼠兔在赤狐、艾虎和香鼬的食物中所出现的频次分别为100％、96．1％、100％,高原鼢鼠在3种天敌动物的食物中所出现的频次分别为87．5％、73．2％、0％。3种天敌动物对高原鼠兔和高原鼢鼠的捕食强度分别为0．703％和0．038％,高原鼠兔和高原鼢鼠所承受的捕食风险分别为0．780和0．393。高原鼠兔在高的捕食风险下通过行为对策和繁殖对策增加其适合度,而承受捕食风险较小的高原鼢鼠主要通过封闭的洞道系统和高的存活率增加其适合度。     

相关风险因子对高原鼠兔摄食行为的影响

研究了捕食风险环境中集和洞口距离对高原鼠兔摄食行为的影响。结果表明,集群数量的增加不仅降低了警觉行为,同时也减少了摄食行为,在高风险环境中,集群为1时的取食行为强度最大,低风险环境中,为0时最大,警觉行为主要出现在距洞口2m的范围内,其行为强度与洞口踪影职责负相关,当洞口距离大于3m时,风险处理区的高原鼠兔几乎无警觉行为出现,且该处理区的取食区域几乎压缩的洞口旁,研究结果表明,在捕食风险环境中,高原鼠兔摄食行为与集群和洞口距离之间具有复杂的关系,其行为决策反映了降低风险与摄取食物间的权衡,行为目标是在降低捕食风险的同时尽可能地取食食物。     

典型草原区达乌尔鼠兔繁殖生态学的初步研究

达乌尔鼠兔是我国典型草原区的主要鼠种之一,对其繁殖特征知之甚少。作者于2009年7-11月和2010年4-9月在内蒙古典型草原区采用整洞群夹捕的取样方法捕获了199只达乌尔鼠兔(Ochotona dauurica),对其种群数量、性比、繁殖特征和年龄结构进行了研究。结果显示：2009年鼠兔数量118只,2010年81只;雌鼠数量显著多于雄鼠;达乌尔鼠兔的繁殖期为3-9月,高峰期集中在4-6月份,平均胎仔数为6.15±0.50(n=13);2009年的7-9月幼年和亚成年比例均小于50%,成年个体成为种群的重要成分;2010年幼体主要集中在5-7月份,且6月和7月幼体和亚成体的数量超过了成年鼠兔的数量,8-9月份种群的主要成员为亚成年和成年鼠兔。达乌尔鼠兔种群繁殖特征是对草原环境适应的体现。     

高原鼠兔与达乌尔鼠兔的摄食行为及对栖息地适应性的研究

通过对标志高原鼠兔和达乌尔鼠兔直接观察的方法,对它们的摄食行为及栖息地适应性进行了研究。两种鼠兔的摄食行为链存在着明显趋同的行为程序时间系列。在摄食活动中,前者用于防御敌害的时间分配较多。而达乌尔鼠兔则花费更多的时间于采食。对小生境内的高大植株进行刈割,是高原鼠兔保持其防御视野开阔,降低被捕食风险的适应性策略;达乌尔鼠兔则善于利用栖息地内高大植株覆盖物作为它们的临时隐蔽所,以有效地躲避敌害。这表明它们具有反捕食的行为调控能力,也证明捕食风险强化了物种对栖息地的选择。     

典型草原区达乌尔鼠兔年龄划分标准

年龄鉴定是研究动物种群生态学的重要基础.作者于2009 ～2010年间在内蒙古典型草原区采用整洞群夹捕的取样方法捕获了198只达乌尔鼠兔(Ochotona dauurica,116只雌鼠,82只雄鼠).在对样本进行常规解剖和数据记录后,根据样本的胴体重频次分布特征并参照繁殖特征,对达乌尔鼠兔进行年龄划分.分析结果表明,达乌尔鼠兔胴体重存在显著的性别差异,据此本文按照性别将达乌尔鼠兔划分如下3个年龄组,雌性:幼年组(胴体重≤55 g)、亚成年组(55 g＜胴体重＜75 g)、成年组(胴体重≥75g);雄鼠:幼年组(胴体重≤55 g)、亚成年组(55 g＜胴体重＜85 g)、成年组(胴体重≥85 g).并根据达乌尔鼠兔体重与胴体重之间的相互关系,建立了利用体重鉴定达乌尔鼠兔年龄的依据.本方法可为野外达乌尔鼠兔的年龄划分和种群结构动态研究提供参考依据.     

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.