遗传物质的发现者之一——麦卡锡

1944年,3位科学家艾弗里、麦卡锡和麦克劳德在DNA遗传本质方面的发现是20世纪最重要的发现之一,这个发现打开了生物学革命的大门,从而改变了人类对自然界的看法,这项研究还为1953年沃森和克里克DNA双螺旋结构的发现奠定了坚实的基础,但不幸的是3位科学家都未曾荣获诺贝尔奖.通过介绍麦克林·麦卡锡的科学研究,从而对这项发现的基本状况有一个基本的了解.     

苏联猛犸象的研究

猛犸象(Elephas primigenius)是最著名的动物化石之一。在欧洲,西伯利亚,中国北部以及其他区域内的许多地方,都曾发现过大批这种动物的遗体,而且它们的庞大的躯体与奇特的形状早就吸引了人们的注意。此外,在亚洲及欧洲的冻土带内,曾发现过这种动物的,连皮,肉和毛都保存着的完整的尸体。古代极北地区的居民,当他们发现了这些由于海岸崩裂而从地下深处露出来的尸体后,曾企图寻求关于这些奇怪动物的外貌的解释。在耶库     

丘脑-皮层感觉通路上的反馈调节

皮层投射到丘脑的纤维数量约为丘脑至皮层的纤维数量的10倍,因此许多研究者都认为这一庞大的反馈网络必然在感觉信息的加工过程中发挥着重要的作用,而越来越多的证据也显示,来自皮层的反馈调节在修整丘脑反应方面起到了非常关键的作用.本文即从解剖学和生理学的角度对皮层.丘脑反馈调节的相关研究做一简要综述.     

c-Cbl介导了hSef的泛素化和降解

Sef(similar expression to fgf genes)作为FGF信号通路中可诱导的拮抗分子相继在斑马鱼,小鼠,和人类中被鉴定出来,并进行了相应的功能研究.目前对于Sef蛋白本身稳定性的研究还未见报道.对c-Cbl对Sef稳定性的影响进行了研究.免疫荧光实验表明Sef能够和c-Cbl蛋白在细胞中发生共定位,随后的免疫共沉淀实验证明Sef能够和c-Cbl发生相互作用.体内泛素化实验表明c-Cbl能够使Sef发生明显的泛素化作用.这种泛素化最终导致了Sef本身的剂量依赖性的降解.针对c-Cbl的siRNA表达也使Sef稳定细胞系的表达水平得到恢复.结果表明,c-Cbl对Sef的泛素化及降解可能作为一种调控拮抗因子的蛋白质水平从而最终调节信号通路的一种机制.     

远古人类的狩猎武器

当你走进中国科学院古脊椎动物与古人类研究所内中国古动物馆的树华古人类馆,你注意到展柜里那些圆形的石头标本了吗?这就是10多万年前古人类狩猎与防身的武器——石球.与现在的手枪、步枪和机关枪的子弹和大炮的炮弹等异曲同工的是,这些远古社会古人类使用的石球是一种远距离杀伤武器.     

脑电图数据的相关性分析

目的:本文对客观记录的脑电图数据进行相关性分析,为正确理解人脑的不同局部以及局部与整体之间的相关性提供基础实验依据和理论根据,为脑电图研究的其它分析做基础分析.方法:分别对10导联电极和21导联电极的两组脑电图数据做互相关和自相关的相关性分析,得出在不同条件、事件下脑的各导联电极的自相关分析结果和左右对称导联电极的互相关分析结果,最后得出相关性值随实验条件和事件的具体变化.数据处理和统计分析采用独立设计的脑电图分析工具箱和相关性分析程序.结果:脑电图数据经过相关性分析后得到的相关图具有和脑电波相似的波形,具有周期性,时间滞后对应的标准化的相关图显示出相关性值的第一个主峰是最大的,主峰频率一般在8到13Hz的脑电波频段内;最后得到的相关性值随事件的变化而改变的结果说明实验事件对相关性的影响.结论:自相关和互相关都是随着时间滞后的增大而逐渐减小;波具有较强的相关性;相关图在从零延迟开始时间滞后所出现的第一个波峰是主峰,反应出相对较强的相关性;从大量数据的分析最后得到的相关性与事件的关系表明相关性是受事件影响的.     

高黎贡山北段东西坡种子植物区系的比较研究

高黎贡山北段的东西坡由于在降雨量和热量分配等方面存在着显著的差异,致使东西坡在植物的种类、组成及区系特征等方面表现出明显的差异.东坡记载野生种子植物152科,580属,1475种及192变种(亚种),西坡记载野生种子植物162科,659属,1804种及186变种(亚种).东西坡种子植物科、属、种的对比分析表明:1)东西坡现代种子植物区系具有相同的历史渊源,但其区系联系减弱了,东西坡区系相似性程度,依科、属、种的顺序依次递减;2)西坡现代种子植物区系比东坡具有更为深刻的热带起源烙印.就科、属、种三个水平来说,东坡的热带成分低于西坡,温带成分高于西坡.许多典型的泛热带大科在西坡比东坡有着更为丰富的种类,其中有些泛热带科分子在东坡缺乏分布,而在西坡找到了合适的驻留之地;3)西坡现代种子植物区系与东喜马拉雅植物区系的联系比东坡紧密,而东坡与高黎贡山以东的区系联系比西坡密切,由于高黎贡山山脉的阻隔,近代植物物种的东西坡交流发生了障碍;4)西坡生态地理环境比东坡更有利于物种的生存、繁衍和分化,它既是古老成分的避难所,又是孕育新生成分的摇篮.     

鸡的瞬膜

瞬膜(nictitating membrane),又称第三眼睑,是一种保护眼球、防止灰尘的结构.鸟类的瞬膜位于眼眶的前眼角,为半透明的膜,其内缘具有一种羽毛上皮,借以刷洗角膜上的灰尘.在飞行时能遮覆眼球,以避免干燥气流和灰尘对眼球的伤害.由于瞬膜在鸟类睁眼的一瞬间迅速缩回前眼角,很难拍摄到.最近费了好大的周折,终于拍到了理想的鸡瞬膜照片,现予以发表供生物学界的同行共享(友情提示:如引用请注明原作者).     

江西考古的结缘地——安义

正友情笔者从事史前考古学已40余年,让我最难忘的是与江西安义县文物爱好者胡贤钢的友情,这种友情还需从1988年讲起。当年,胡贤钢20岁,是安义县食品厂的一名工人。他勤奋好学,对历史文化有着浓厚的兴趣。他从中学历史书中掌握的一些史前学知识,来了解远古人类使用过的生产和生活工具。在休假的时候,他常常在自己家乡的丘陵和台地采集古人类使用过的工具来收藏。当时他的家庭人口多,经济拮据,但是他喜欢读书,他的父母支持他的爱好,舍得花钱给他买一些书。1988年在县的新华书店曾花一角钱,     

叶绿体基因组研究进展

作为植物细胞器的重要组成部分和光合作用的器官,叶绿体在生物进化的漫长历史中发挥了重要作用.伴随着生物技术的深入发展,人们发现叶绿体基因组结构和序列的信息在揭示物种起源、进化演变及其不同物种之间的亲缘关系等方面具有重要价值.与此同时,比核转化具有明显优势的叶绿体转化技术在遗传改良、生物制剂的生产等方面显示出巨大潜力,而叶绿体基因组结构和序列分析则是叶绿体转化的基石.基于叶绿体的这些重要作用,收集整理了有关的资料,从几个方面归纳了本领域最近的研究进展,希望能使读者对迅速发展的叶绿体基因组研究有更全面的了解,以及对叶绿体基因组在物种的进化、遗传、系统发育关系等方面的作用有更深刻的认识,同时也希望对叶绿体转化技术的研究和广泛应用产生积极作用.     

TiLIA: a software package for image analysis of firefly flash patterns

As flash signaling patterns of fireflies are species specific, signal‐pattern analysis is important for understanding this system of communication. Here, we present time‐lapse image analysis (TiLIA), a free open‐source software package for signal and flight pattern analyses of fireflies that uses video‐recorded image data. TiLIA enables flight path tracing of individual fireflies and provides frame‐by‐frame coordinates and light intensity data. As an example of TiLIA capabilities, we demonstrate flash pattern analysis of the fireflies Luciola cruciata and L. lateralis during courtship behavior.     

萤火虫的研究、保护及开发利用进展

萤火虫是萤科和凹眼萤科昆虫的统称,既是科学研究的良好材料,也具有巨大的产业潜力。本文从分类学(包括分类现状和分子系统学研究进展)、生物学(包括生活史、分布、天敌、视蛋白、人工光照的影响、生物指示作用、体内共生菌等)、行为学(包括发光、求偶、交配、取食、防御、报警、拟态、叠背、成虫后多次蜕皮等)等方面全面梳理了国内外萤火虫基础研究的进展,分析了萤火虫的消亡原因(环境污染、旅游影响、科普欠缺、生物入侵及其它等)、保护情况并提出了保护萤火虫的若干措施建议,系统地阐述了当前国内外萤火虫开发利用的现状,最后从萤火虫的科学研究、资源保护、人工养殖、产业发展等方面提出了建议,以期推动萤火虫的研究和资源开发工作。     

The ecological impact of an introduced population on a native population in the firefly Luciola cruciata (Coleoptera: Lampyridae)

In Japan, Tatsuno Town has been famous for many Luciola cruciata fireflies emerging every summer at least since the 1920s. However, in the 1960s, L. cruciata fireflies were intentionally introduced from the Lake Biwa area into Matsuo-kyo, the most famous habitat of fireflies in that town. In this study, I examined ambient temperatures and flash rates of L. cruciata at four sites including Matsuo-kyo in the Tatsuno area and two sites in the Lake Biwa area. The linear regression of flash rates on temperatures indicated that the Matsuo-kyo population was distinct from the other three populations native to the Tatsuno area, but similar to the two populations native to the Lake Biwa area in terms of flash rates. These results were also supported by a recent molecular biological study, suggesting that the introduced fireflies had a strong ecological impact on the native ones at Matsuo-kyo. The present study emphasizes that we should not transport and release L. cruciata fireflies without careful consideration.     

Spontaneous flash communication of females in an Asian firefly

Fireflies are well known for the use of bioluminescence for sexual communication. In species using flash signals for pair formation, species and sexual identity are conferred by flash timing parameters such as flash duration, flash interval, flash number, and response delay. In dialog fireflies in North America, the male is the advertiser and the female is the responder. In these species, the male flash signal parameter varies depending on species, but the female flash signal parameter is limited only to response delay. However, in fireflies other than dialog fireflies, sexual flash communication is not well studied. Although many female-advertisement-like fireflies are reported, we have no confirmed case of sexual communication in a female-advertisement species. Here, we report the sexual flash communication of an Asian firefly, Luciola (Hotaria) parvula, in which the female flashes spontaneously. By using an electronic firefly, we confirm experimentally that males are specifically attracted to flashes with a female-specific flash duration. This is the first experimental report of sexual communication of a female advertiser in firefly communication. In this species, females call males usually with spontaneous flashes unlike dialog fireflies.     

The occurrence of synchrony in the North American fireflyPhotinus carolinus (Coleoptera: Lampyridae)

Synchronous flashing has been described for some Southeast Asian fireflies but has rarely been reported in North American fireflies. Our field observations indicated thatPhotinus carolinus flash synchronously. The flash pattern of individualP. carolinus was characterized by a burst of five to eight flashes over a period of approximately 4 s. These flash bursts were repeated about every 12 s. Groups of fireflies comprised individuals exhibiting this species-specific flash pattern. Remarkably, members of the group flashed synchronously: Flash bursts started and stopped at the same time and the flashes among individuals occurred at the same time as well. We used low-light level videography to examine this behavior in caged groups of (3 or 10) fireflies for synchronic flashing. The occurrence of concurrent rhythmic group flashing satisfies the criteria for synchrony as defined by Buck (1988). The intermittent nature of the bursts of flashes shown byP. carolinus makes this a discontinuous synchrony. The mechanisms underlying discontinuous synchrony are not known.     

Fireflies as a catalyst for science education

The study of fireflies makes an ideal subject for introducing students of all ages to the world of science, conservation biology, field studies and the importance of observation and understanding connections in the natural world.The synchronous fireflies, Photinus carolinus of the Great Smoky Mountains National Park's Elkmont Historic District can be used as a basis for classroom and field activities in subjects as diverse as conservation biology, economics, geography, ecology, governmental policy, zoology, history, taxonomy and animal behavior.Having been fascinated with the synchronous fireflies for over two decades, I will use the life cycle of the Elkmont Phontinus carolinus found in the Great Smoky Mountains National Park as an example.     

Firefly Femmes Fatales: A Case Study in the Semiotics of Deception

Mimicry and deception are two important issues in studies about animal communication. The reliability of animal signs and the problem of the benefits of deceiving in sign exchanges are interesting topics in the evolution of communication. In this paper, we intend to contribute to an understanding of deception by studying the case of aggressive signal mimicry in fireflies, investigated by James Lloyd. Firefly femmes fatales are specialized in mimicking the mating signals of other species of fireflies with the purpose of attracting responding males to become their prey. These aggressive mimics are a major factor in the survival and reproduction of both prey and predator. It is a case of deception through active falsification of information that leads to efficient predation by femmes fatales fireflies and triggered evolutionary processes in their preys’ communicative behaviors. There are even nested coevolutionary interactions between these fireflies, leading to a remarkable system of deceptive and counterdeceptive signaling behaviors. We develop here a semiotic model of firefly deception and also consider ideas advanced by Lloyd about the evolution of communication, acknowledging that deception can be part of the explanation of why communication evolves towards increasing complexity. Increasingly complex sign exchanges between fireflies evolve in an extremely slow pace. Even if deceptive maneuvers are played out time and time again between particular firefly individuals, the evolution of the next level of complexity—and thus the next utterance in the dialogue between species—is likely to take an immense amount of generations.     

Fireflies with or without prespermatophores: Evolutionary origins and life-history consequences

During mating, some male North American fireflies produce spermatophores from prespermatophores in their paired reproductive accessory glands. Other species of fireflies have neither prespermatophores nor spermatophores. To establish a pattern of spermatophore occurrence across firefly species, we examined the male internal reproductive system in 20 Japanese species belonging to 10 genera for the presence or absence of prespermatophores. Twelve species from seven genera produced prespermatophores, while eight species from three genera did not. Superimposed on a molecular phylogeny of Japanese fireflies based on mitochondrial 16S ribosomal DNA sequences, the basal group was prespermatophore producers. Prespermatophores appear to have been lost in two different lineages. Species without prespermatophores are characterized by degeneration of both the forewings and hindwings, and by body gigantism in females.     

Examining the Role of Cuticular Hydrocarbons in Firefly Species Recognition

During animal courtship, multiple signals transmitted in different sensory modalities may be used to recognize potential mates. In fireflies (Coleoptera: Lampyridae), nocturnally active species rely on long-range bioluminescent signals for species, sex, and mate recognition, while several diurnally active species rely on pheromonal signals. Although in many insects non-volatile cuticular hydrocarbons (CHC) also function in species and sex discrimination, little is known about the potential role of CHC in fireflies. Here, we used gas chromatography to characterize species and sex differences in the CHC profiles of several North American fireflies, including three nocturnal and two diurnal species. Additionally, we conducted behavioral bioassays to determine whether firefly males (the searching sex) were differentially attracted to extracts from conspecific vs. heterospecific females. Gas chromatography revealed that nocturnal Photinus fireflies had low or undetectable CHC levels in both sexes, while diurnal fireflies showed higher CHC levels. No major sex differences in CHC profiles were observed for any firefly species. Behavioral bioassays demonstrated that males of the diurnal firefly Ellychnia corrusca were preferentially attracted to chemical extracts from conspecific vs. heterospecific females, while males of the remaining species showed no discrimination. These results suggest that while CHC may function as species recognition signals for some diurnal fireflies, these compounds are unlikely to be important contact signals in nocturnal Photinus fireflies.     

Flash Precision at the Start of Synchrony in Photuris frontalis

Synchronous flashing occurs in certain species of SoutheastAsian and North American fireflies. Most Southeast Asian synchronyinvolves stationary congregating fireflies, but North Americansynchrony occurs in flying fireflies that do not congregate.Southeast Asian synchrony is usually continuous, but North Americansynchrony is interrupted. Photuris frontalis, the only memberof the North American genus Photuris to synchronize, shows anintermittent synchrony. This involves synchronization and repeatedre-synchronizations while in flight. The precision that occursat the start of synchrony was studied in Ph. frontalis usingcaged fireflies and photometry. Barrier experiments (using twofireflies) or flash entrainment experiments (using one LED andone firefly) were performed to measure the temporal precisionof the first entrained flash. In both cases, the first entrainedflash was close to unison synchrony (phase = 1.0) and showedlittle variability. The behavioral implications of the abilityto synchronize with the first entrained flash are not known,but it might facilitate male-male interactions during brief,transient encounters such as maintaining distance between closelyflying males in search of females.