蛹期薜荔榕小蜂的琼脂培养

【目的】薜荔Ficus pumila var. pumila瘦果具有极高的营养食用价值,其结实依赖薜荔榕小蜂Wiebesia pumilae传粉。本研究旨在探讨蛹期植食性寄生蜂室内培养的可能性。【方法】在不同温度(22, 24, 26, 28, 30和32℃)和光周期(0L∶24D, 10L∶14D, 12L∶12D, 14L∶10D和24L∶0D)条件下在琼脂培养基上培养薜荔榕小蜂蛹,测定薜荔榕小蜂蛹期各阶段的发育形态和历期,雌成蜂寿命以及虫瘿含水量,并观察虫瘿形态发育过程。【结果】在22~28℃范围内,薜荔榕小蜂蛹的发育速率随温度升高而加快,羽化时间也随之提前,但羽化率没有显著差异。28℃琼脂培养条件下,薜荔榕小蜂蛹期发育历期最短,从预蛹发育至成虫的历期雌蜂为25.65 d,雄蜂为21.79 d,比同期自然条件下的雌、雄薜荔榕小蜂蛹期发育历期缩短了44.00 d;30℃下,少部分榕小蜂蛹能发育至熟蛹期;32℃下,榕小蜂预蛹滞育,推测30℃可能是该种榕小蜂蛹发育的耐热极端温度。不同光周期条件下,薜荔榕小蜂蛹期的发育速率及羽化率均无显著差异。在22~28℃范围内,温度越高,虫瘿含水量下降越快,培养时间越长,虫瘿含水量越低。28℃下琼脂培养的薜荔榕小蜂羽化时的虫瘿含水量(41.79%)极显著低于自然发育的个体(51.63%)。低含水量导致虫瘿壳非常坚硬,薜荔榕小蜂开掘出飞孔困难,这可能是琼脂培养条件下的薜荔榕小蜂羽化未能出飞的主要原因。【结论】本研究的琼脂培养方法为植食性寄生蜂蛹期发育的连续性观察,以及部分实验虫源的获取提供了可能。     

小叶榕隐头果内加利里金小蜂的发生规律

小叶榕Ficus microcarpa是一种广泛分布于亚洲热带和亚热带地区的雌雄同株榕树,在它的隐头果中,除了专一性传粉的榕小蜂外,还寄生着多种非传粉小蜂,这些非传粉小蜂在榕果发育的不同时期来到果外产卵,对榕树和传粉榕小蜂繁衍后代产生不同的影响。加利里金小蜂Odontofroggatia galili是寄生于小叶榕雌花子房里的主要非传粉小蜂。本文在2012~2013年对该种小蜂的发生规律进行了研究,结果表明:该种小蜂雌雄蜂有翅,雄蜂二型,个体大小有显著差异。加利里金小蜂在榕果的雌花前期产卵,能独立造瘿;在西双版纳地区,干热季和雨季从卵发育到成虫羽化需31~38 d,雾凉季则长达58~72 d。成虫在榕果雄花期羽化出蜂,大多数雄蜂在苞片口等待羽化出果的雌蜂交配,雌雄蜂通常仅交配一次;为争夺交配机会,雄蜂间存在激烈打斗,且个体大者获交配机会多。成虫期雌蜂寿命2 d,雄蜂寿命仅1 d。小叶榕40%的树上隐头果内有加利里金小蜂寄生,但不同地区寄生率和单果内加利里金小蜂雌雄蜂数量树间均存在显著差异。在原生地西双版纳地区加利里金小蜂种群小,传粉榕小蜂种群占主导地位;而在引入地昆明地区,加利里金小蜂发生频率高,种群显著较大;随着纬度北移和海拔升高,在榕果内罕见有传粉榕小蜂传粉和繁殖,而加利里金小蜂种群则不断升高。说明小叶榕在海拔较高和纬度偏北地区栽种,不适宜传粉榕小蜂繁殖,而非传粉的加利里金小蜂则较为适应,获得成功繁殖及种群扩张。     

西双版纳鸡嗉果榕内一种非传粉小蜂的性比调节

对西双版纳广泛分布的鸡嗉果榕（Ficus semicordata）雄树上寄生的一种非传粉榕小蜂Apocryptophagus sp.进行控制梯度放蜂实验,结合产卵行为、交配行为观察,定量研究了该种非传粉榕小蜂的性比率.结果表明：Apocryptophagus sp.雌蜂在传粉榕小蜂（Ceratosolen gravelyi）产卵后的第3天开始访问榕果,从果外完成产卵,产卵时间持续2d左右.发育成熟以后,其雄蜂几乎与传粉榕小蜂雄蜂同时羽化,雄蜂咬开寄生有其雌蜂的瘿花并进行交配,雌蜂交配后从瘿花内羽化出来离开榕果,去寻找新的处于接受期的榕果,而雄蜂一直留在其寄生的榕果内直至死亡.后代性比与局域配偶竞争理论预测一致：性比偏雌,随着在同一榕果产卵的繁殖雌蜂数量的增加,后代性比上升;同时,单个榕果内的后代数量也上升,而平均后代数量却显著下降.在个体水平上,当1头雌蜂在榕果上产卵时,后代性比与后代数量呈显著的负相关关系.     

爱玉及其传粉昆虫的共生关系

爱玉是榕属攀援灌木,其隐头花序中生活着薜荔榕小蜂,爱玉一年两次开花,雌雄株比1：2,雌花序中平均有5503朵雌花。雄花序中平均有6308朵瘿花,自然状态上结实率和成虫瘿率分别为83.52%,51.33%。薜荔榕小蜂一年两代,1只雌蜂进入花序平均可产约600个卵或使1391朵雌花受粉结实,爱玉依赖薜荔榕小蜂传粉,否则不能结实;薜荔榕小蜂是惟一能进入花序的传粉者并依靠爱玉花序得以栖息,二者在形态结构。生理功能上高度互适,生活史上完全吻合衔接。生态策略上紧密协调,构成复杂而又精细的共生体系。     

西双版纳热带雨林聚果榕小蜂的传粉生态学

对聚果榕小蜂（Ceratosolen sp.)传粉生态学进行了首次研究。结果表明,聚果榕小蜂的雄蜂比雄蜂早羽化数小时;雄蜂羽化不能自行打开瘿花和果肉出蜂口,两个出蜂口均需雄蜂开凿,而聚果榕的成熟花粉,不能自行地从开裂处散发出来,必须经榕小蜂的繁殖性雌蜂采集才能散到表面,羽化后的雌蜂的开裂的雄花中不停地用触角柄节,口器上颚和足推动和采集花粉,雄蜂飞出熟榕果寻找嫩隐头花果,一般在外飞5－80min,雌蜂进入嫩聚果榕的隐头花果内后,立即把粘附在足,头触角和身上的花粉不停地推动到长柱头雌花中,授粉行为长达4－9h,然后,才把卵产在短柱头雌花中。     

西双版纳鸡嗉果榕小蜂繁殖和传粉行为

鸡嗉果榕 Ficus semicordata Buch.-Ham.ex J. E. Sm.是西双版纳地区常见的榕属植物,它是热带雨林生态系统中的一类先锋树种,当热带雨林被破坏后,它最先在林缘、沟谷和路边迅速生长起来,是热带和亚热带地区森林生态系统恢复初期一类重要物种。在西双版纳通过不同样地定树、定期生态学观察和室内剖查不同生长时期的鸡嗉果榕隐头果的方法,对榕小蜂繁殖和传粉行为进行了研究,结果表明,鸡嗉果榕雌雄异株,在西双版纳一年结2～3次隐头果,雌株隐头果内小花由榕小蜂传粉后产生种子。雄株则产生雄花和中性小花,中性小花专门供给传粉小蜂产卵繁殖后代。鸡嗉果榕小蜂Ceratosolen gravelyi Grandi是鸡嗉果榕唯一的传粉昆虫。传粉小蜂的雄蜂比雌蜂早羽化30～90 min,一部分雄虫羽化后,在虫瘿上爬动寻找雌蜂寄生的瘿花,一找到雌蜂寄生的瘿花,就咬破虫瘿的一个小口,把生殖器伸进瘿花与雌蜂交配,一部分雄蜂则在果肉上咬出蜂口。雌蜂交配后,顶大交配孔出蜂爬到雄花区采集花粉,然后,飞出寻找鸡嗉果榕雌花期的嫩隐头果传粉和繁殖后代。到鸡嗉果榕雌株传粉的小蜂能飞翔300～500 m,进果腔传粉行为长达5～27 h,传完粉3～5 h在果腔内死亡。到雄株上繁殖的小蜂一般飞翔在20～100 m左右近距离寻找嫩隐头果,进果腔产卵,每只小蜂在无干扰的情况下可产400多粒卵。除传粉榕小蜂外,在鸡嗉果榕雄株隐头果上还有4种植食、造瘿和复寄生等非传粉小蜂,它们对传粉小蜂的种群繁衍影响很大,常使传粉小蜂的种群数量降低25～70%。每个隐头果内进传粉小蜂量多少对鸡嗉果榕和榕小蜂繁殖有关,最佳进蜂量为3只,高或低于最佳进蜂量对鸡嗉果榕树和它的传粉小蜂繁殖均不利。     

薜荔榕小蜂对薜荔和爱玉子雌花期榕果挥发物的行为反应

薜荔和爱玉子均属雌雄异株桑科榕属植物,两者互为原变种与变种的关系,分别与薜荔传粉小蜂和爱玉子传粉小蜂(二者互为隐存种)建立了专性共生关系,榕树榕果挥发物在维系传粉小蜂与其寄主的共生关系上起着重要作用。利用Y型嗅觉仪测定薜荔榕小蜂(薜荔和爱玉子的传粉小蜂)对薜荔和爱玉子雌花期榕果挥发物的行为反应。结果表明:(1)雌花期果型的大小对薜荔榕小蜂行为反应无显著影响,薜荔大、小果型雌花期雌(雄)榕果挥发物对其传粉小蜂均具有强烈的吸引作用;(2)榕果挥发物浓度影响薜荔榕小蜂行为反应,薜荔、爱玉子雌花期雌(雄)榕果挥发物对其传粉小蜂的吸引作用均可能存在阈值反应,即榕果挥发物浓度未超过阈值时,雌花期榕果挥发物对传粉小蜂的吸引作用与挥发物浓度成正相关关系,而一旦超过阈值,榕果挥发物对传粉蜂的吸引作用显著下降,表明寄主榕果挥发物浓度影响传粉小蜂的寄主定位;(3)薜荔传粉小蜂对低浓度爱玉子雌花期雌(雄)榕果挥发物、爱玉子传粉小蜂对低浓度薜荔雌花期雌(雄)榕果挥发物均既无趋向也无驱避行为;薜荔传粉小蜂对高浓度的爱玉子雌花期雌(雄)榕果挥发物表现为显著的驱避行为,而爱玉子传粉小蜂对高浓度薜荔雌(雄)雌花期榕果挥发物表现为显著的趋向行为,因此,薜荔传粉小蜂与爱玉子传粉小蜂存在寄主专一性不对称现象,爱玉子传粉小蜂进入薜荔雌(雄)果内传粉或产卵的可能性较大,而福州地区的薜荔传粉小蜂可能难以进入爱玉子雌(雄)果内传粉或产卵。本研究结果将为榕-蜂共生体系的化学生态学理论研究以及爱玉子栽培提供科学依据。     

西双版纳鸡嗉果榕内一种非传粉小蜂的性比调节

对西双版纳广泛分布的鸡嗉果榕(Ficus semicordata)雄树上寄生的一种非传粉榕小蜂Apocryptophagus sp.进行控制梯度放蜂实验,结合产卵行为、交配行为观察,定量研究了该种非传粉榕小蜂的性比率.结果表明: Apocryptophagus sp.雌蜂在传粉榕小蜂(Ceratosolen gravelyi)产卵后的第3天开始访问榕果,从果外完成产卵,产卵时间持续2 d左右.发育成熟以后,其雄蜂几乎与传粉榕小蜂雄蜂同时羽化,雄蜂咬开寄生有其雌蜂的瘿花并进行交配,雌蜂交配后从瘿花内羽化出来离开榕果,去寻找新的处于接受期的榕果,而雄蜂一直留在其寄生的榕果内直至死亡.后代性比与局域配偶竞争理论预测一致：性比偏雌,随着在同一榕果产卵的繁殖雌蜂数量的增加,后代性比上升;同时,单个榕果内的后代数量也上升,而平均后代数量却显著下降.在个体水平上,当1头雌蜂在榕果上产卵时,后代性比与后代数量呈显著的负相关关系.     

钝叶榕(Ficus curtipes)非传粉小蜂交配行为

榕树及其传粉榕小蜂繁殖上相互依存,被认为是生物界中协同进化时间最悠久,相互关系最密切的一对生物;在大多数榕树种类的隐头花序内,除了传粉榕小蜂外,还共存着多种非传粉小蜂,它们的繁殖行为直接影响着榕树和传粉榕小蜂的繁殖和互惠稳定.钝叶榕(Ficus curtipes Corner),是一种雌雄同株的绞杀性榕树.研究在西双版纳热带植物园里共收集钝叶榕100个隐头果内的榕小蜂,获得9493号标本;其中,包括1种传粉小蜂和5种非传粉小蜂,钝叶榕传粉小蜂Eupristina sp.占总数的44.66%,杨氏榕树金小蜂Diaziella yangi 占46.13%,而其它4种非传粉小蜂(Lipothymus sp., Sycobia sp., Philotrypesis sp.和Sycoscopter sp.)仅占9.20%.前3种榕小蜂雌蜂进到果腔产卵,其余3种在果外产卵.观测23个钝叶榕榕果出蜂情况发现,6种榕小蜂在钝叶榕隐头花序内遵循严格的羽化出蜂顺序,首先是Sycobia sp.,次之是Lipothymus sp.,再次之是杨氏榕树金小蜂,最后是钝叶榕传粉小蜂、Philotrypesis sp.和Sycoscopter sp..5种非传粉小蜂的交配场所与雄蜂翅型无关,雄蜂有翅型的杨氏榕树金小蜂大部分交配在果内完成,而且它们的雄蜂为争夺交配机会存在激烈的打斗行为;雄蜂无翅型的Lipothymus sp.有部分雄蜂爬出隐头果,在果壁和附近的叶片背面交配;雄蜂有翅型的Sycobia sp.,其所有交配都发生在果外;Philotrypesis sp.和Sycoscopter sp. 雄蜂均无翅,它们的交配全发生在果内.局域配偶竞争使榕小蜂性比偏雌,杨氏榕树金小蜂雄蜂虽然有翅,但大部分交配发生在榕果内,这将影响其最佳的性比率.因此,依赖雄蜂翅型并不能很好地预测榕小蜂的交配场所和性比率.     

栽培爱玉的传粉生态

栽培爱玉传粉生态的研究表明,栽培爱玉开花期明显分为春、秋两季,持续时间均较野生爱玉长.爱玉不能依靠生长于原变种薜荔花序中的小蜂授粉或产卵,在野生爱玉传粉小蜂隔离的情况下,小蜂缺失造成传粉系统损毁.栽培爱玉可通过人工引入传粉小蜂建立新种群,但传粉系统修复比较缓慢,历经4年花序挂树率仅达51.11%、挂树花序的平均结果率为64.37%,平均成虫瘿率为64.35%.花序发育的雌花期和雄花期重叠度低、小蜂出飞过于集中、进入花序的小蜂数量少或缺失是造成共生双方繁殖率低下的原因.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.