性的起源及其生物学意义

性的起源及其生物学意义刘培生有性生殖的出现,标志着生物进化的一个新阶段。然而,现在还没有任何基本生物学理由可以说明,如果没有性别,则繁殖、变异和进化就不能无限地进行下去。因此,从绝对意义上讲,性别不是绝对必需品,而是“奢侈品”。可是,性别是个很有利很...     

生物多样性的起源

生物多样性的起源相对于人的一生来说,自然生态系统似乎是永恒而稳定的。除非被人类的活动或自然界的灾变,如大火、洪水、火山爆发等所干扰,草地、沙漠、森林和冻原似乎都是不变的。然而,纵观一个行星的历史,变化却恰恰是生物多样性产生的根源。本章将阐述已经创造...     

漫谈生物的发光

发光生物的分布具有发光能力的生物,在大自然中分布很广,其中少数为一些细菌和真菌,大多数是存在于动物界的一些物种。细菌中的发光细菌(luminous bacteria),主要是海产的发光性水生微生物(plankton),目前已知的发光细菌,不下百十种之多,其中具有显著发光现象的有:磷光假单胞菌(photobacterium phosphoreum)、费氏无色菌(A chromobacter fisheri)、磷光弧菌(Vibrio phosphorescens)和发光杆菌(Bacillus photogenus)。这些发光细菌,除了常常引起夜间海面发光外,还由于它们的孳生繁殖,成为被污染的死鱼、水产加工品、尸肉在黑暗中发光的原因。在缺少冷藏设备的过去年代,     

发光甲虫与生物荧光

生物荧光是活体生物自身可以发光的有趣生命现象。具有这一现象的生物存在于生物四界中,但目前关于这一现象的研究报道主要来自于昆虫,尤其是以萤火虫为代表的发光甲虫的研究。文章对发光甲虫的分类地位、生物荧光发生的原理、发光器官的类型、闪光的“开关”机制、生物荧光的生物学意义及其相关行为学研究进展等进行了详细介绍。此外,还简要提及了荧光生物及其荧光酶的应用。这对了解及探讨生物荧光现象、加强对中国的发光甲虫及其它发光生物的研究及保护利用具有一定的借鉴作用。     

生物大分子起源问题的讨论

关于生命在地球上的起源与进化问题,历来是一个颇多争论的学术领域。显然,人们无法目睹三十几亿年前地球上曾经发出的事情,也难以用实验的方法来重温这一漫长的历史过程,而只能凭借地球留给我们的某些蛛丝马迹去推想,去研究,去探索。伴随着科学技术的发展,有关生命起源的     

生物超弱发光及其应用研究概述

生物超弱发光是生物物理中光生物学的重要内容之一,自１９２３年以来,人们已进行了大量研究。本文评述了生物超弱发光的机理、测量和理化影响因素,总结了生物超弱发光在我国农业和医学中的应用研究,并对初步展望了生物超弱发光的未来研究方向。     

近红外发光卟啉镱-铂配合物的合成及其光物理性质研究

稀土发光材料相比于传统有机荧光染料在生物成像、分子检测和传感等领域具有独特的优势。目前,稀土发光生物探针主要以可见光发射为主,此类探针受限于组织穿透深度,应用范围较窄。具有较大组织穿透能力的近红外(NIR)稀土发光生物探针,由于其发光效率较低而少有报到。本工作合成了一种新型近红外发光的卟啉镱-铂配合物,TFPYb-Pt,表征并测试了该配合物的光物理性质。实验证实TFPYb-Pt具有较大的NIR发光效率(980/1 030 nm,Фem=0.37)和较长的NIR发光寿命(τ=49μs),表明该配合物可望被用于开发新型生物NIR发光探针。     

动物的习惯化学习行为

习惯化是最简单的一种学习类型.在动物界普遍存在.主要介绍了习惯化的形成,动物在习惯化中使行为（反应）发生变化的原因,以及习惯化在动物界具有非常重要的生物学意义.     

Aposematism and Bioluminescence: Experimental evidence from Glow-worm Larvae(Coleoptera: Lampyridae)

Bioluminescence most likely evolved under selection from the visually guided behaviours of co-occurring organisms, in particular that of predators. Many possible functions of light signals have been proposed and some are supported, but whatever their function may be, they make an easy target of the emitter unless it is defended. Therefore, we want to emphasise that in many cases bioluminescence can only have evolved through a defensive function. If this were the case, one would expect multimodal adaptiveness of luminescence with at least some evidence for a defensive function. Light signals could be used in many ways to reduce predation, but for spontaneous glowing species in particular, aposematism seems the only functional strategy. In a preliminary experiment with glowing and non-glowing dummy prey, we found that wild-caught toads discriminated against glowing prey. They showed significantly lower attack responses and higher latencies towards glowing prey dummies. However, some of the toads were less reluctant because they did not distinguish initially between prey with or without the light stimulus. Since the toads were collected in areas abundant with lampyrid glow-worms, which is the only luminous organism at this locality, and our results concur with the general evidence that they may have had previous experiences with this prey, we attribute the result to luminescent aposematism. From the literature, and from our own experiments, we know that toads and many other potential predators experience lampyrids as disagreeable prey. In future experiments we will test whether glow-worms are defended by luminescent aposematism or not. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bioluminescence in firefly larvae: A test of the aposematic display hypothesis (Coleoptera: Lampyridae)

We investigated the hypothesis that bioluminescence in firefly larvae (Coleoptera: Lampyridae) functions as an aposematic display. In two experiments, we confirmed the distastefulness of firefly larvae, and tested the hypothesis that a naive, nocturnal predator can learn to use light signals as aposematic cues for avoiding distasteful prey. Larvae were rejected as acceptable prey by 100% of the house mice (Mus musculus) tested. Mice learned to avoid bitter food associated with light cues significantly faster (P=0.003) than mice presented with food lacking light cues. We conclude that luminescent glowing in firefly larvae meets the requirements of an aposematic signal.     

Proximate Mechanisms of Sexual Selection in the Firefly Photinus pyralis (Coleoptera: Lampyridae)

Male competition in courtships of the firefly Photinus pyralis is intense. Morphometric analysis revealed that male size is variable, possibly exhibiting alternative body plans. We examined the outcomes of courtships to determine the proximate mechanisms of selection that may have led to male allometry. Two distinct selective events exist within mate competition: (1) searching and (2) scramble competition. Although many courtships failed, those without rivals were shorter and successful males spent less time in the mate-guarding position than when several males were in competition. Winners outflashed rivals, but flash dialogs occurred at similar frequencies across rival densities, indicating that females require some quantum of information before mating. Female flash preference was examined in choice tests to evaluate female discrimination ability. Females preferred flashes of greater intensity and precedence. This suggests that flash synchronization is a competitive display rather than a cooperative behavior to maintain female responsiveness. Selection for male size was density dependent: females preferred large males in searching, while small males were favored in scrambles. Simulated scrambles showed that small males have superior locomotor abilities, allowing them to reach the female rapidly. Comparison with a species lacking scrambles, P. macdermotti, revealed that selection in P. pyralis is disruptive, targeting traits alternately, and may have led to the evolution of higher allometric ratios in a species with direct male competition. Both male competition and female choice are important determinants of the outcome of P. pyralis courtships.     

条背萤的闪光求偶行为

水栖萤火虫条背萤Luciola substriata (Gorh.)发出单脉冲周期性特异闪光信号进行求偶。室外观测发现,在23℃、86% RH时,雄萤飞行求偶闪光信号脉冲闪光持续时间为0.52 s,间隔时间为0.28 s,闪光信号的最大亮度为0.6 lx; 雌萤求偶信号周期为 0.67 s,最大亮度为0.4 lx。雄萤发出求偶信号0.22 s后,雌萤发出两个连续的回应信号。第一个回应信号为0.49 s,第二个为0.41 s, 两个回应信号的间隔时间为0.11 s。雄萤发现雌萤回应信号后,降落至离雌萤5～10 cm处,继续发出闪光信号,但闪光脉冲频率减小,闪光脉冲时间为1.23 s,间隔时间为0.50 s。条背萤交配时呈“V”或“一”字形交配姿势。     

Firefly luciferase genes from the subfamilies Psilocladinae and Ototretinae (Lampyridae, Coleoptera)

Firefly luciferase genes have been isolated from approximately 20 species of Lampyrinae, Luciolinae, and Photurinae. These are mostly nocturnal luminescent species that use light signals for sexual communication. In this study, we isolated three cDNAs for firefly luciferase from Psilocladinae (Cyphonocerus ruficollis) and Ototretinae (Drilaster axillaris and Stenocladius azumai), which are diurnal non-luminescent or weakly luminescent species that may use pheromones for communication. The amino acid sequences deduced from the three cDNAs showed 81-89% identities to each other and 60-81% identities with known firefly luciferases. The three purified recombinant proteins showed luminescence and fatty acyl-CoA synthetic activities, as observed in other firefly luciferases. The emission maxima by the three firefly luciferases (λmax, 545-546 nm) were shorter than those by known luciferases from the nocturnal fireflies (λmax, 550-568 nm). These results suggest that the primary structures and enzymatic properties of luciferases are conserved in Lampyridae, but the luminescence colors were red-shifted in nocturnal species compared to diurnal species.     

Glow-worm larvae bioluminescence (Coleoptera: Lampyridae) operates as an aposematic signal upon toads (Bufo bufo)

It is an established fact that the spectacular bioluminescentdisplays of adult fireflies and glow-worms are used as courtshipsignals; however, the survival value of the glowing behaviorof their larvae remained the subject of speculation for manyyears. Our study is the first that demonstrates that lampyridlarvae use luminescence to signal unpalatability to nocturnal,visually guided predators. Wild-caught toads (Bufo bufo) weremore reluctant to attack luminescent artificial prey, and weshow that avoidance learning increased this reluctance. Afterbeing exposed to glow-worm larvae (Lampyris noctiluca), whichthe toads experienced as disagreeable, attack latencies to luminescentprey increased, but not those to nonglowing prey. Not all toadsshowed avoidance learning to the same extent, because of eitherdifferences in previous experience with glow-worms or differencesin memory.     

Flash behavior of femalePhoturis versicolor fireflies (Coleoptera: Lampyridae) in simulated courtship and predatory dialogues

FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.     

Mitochondrial DNA Sequence-Based Population Genetic Structure of the Firefly, Pyrocoelia rufa (Coleoptera: Lampyridae)

The genetic divergence, population genetic structure, and possible speciation of the Korean firefly, Pyrocoelia rufa, were investigated on the midsouthern Korean mainland, coastal islets, a remote offshore island, Jedu-do, and Tsushima Island in Japan. Analysis of DNA sequences from the mitochondrial COI protein-coding gene revealed 20 mtDNA-sequence-based haplotypes with a maximum divergence of 5.5%. Phylogenetic analyses using PAUP, PHYLIP, and networks subdivided the P. rufa into two clades (termed clade A and B) and the minimum nucleotide divergence between them was 3.7%. Clade A occurred throughout the Korean mainland and the coastal islets and Tsushima Island in Japan, whereas clade B was exclusively found on Jeju-do Island. In the analysis of the population genetic structure, clade B formed an independent phylogeographic group, but clade A was further subdivided into three groups: two covering western and eastern parts of the Korean peninsula, respectively, and the other occupying one eastern coastal islet and Japanese Tsushima Island. Considering both phylogeny and population structure of P. rufa, the Jeju-do Island population is obviously differentiated from other P. rufa populations, but the Tsushima Island population was a subset of the Korean coastal islet, Geoje. We interpreted the isolation of the Jeju-do population and the grouping of Tsushima Island with Korean coastal islets in terms of Late Pleistocene-Holocene events. The eastern-western subdivision on the Korean mainland was interpreted partially by the presence of a large major mountain range, which bisects the midpart of the Korean peninsula into western and eastern parts.     

Aspisoma lineatum (Gyllenhal) (Coleoptera: Lampyridae) Firefly: Description of the Immatures, Biological, and Ecological Aspects

Aspisoma lineatum (Gyllenhal) is a common firefly in the Southeastern region of Brazil. Adults and larvae were collected in the municipality of Campinas, state of S?o Paulo, Brazil, and the immature stages were described and reared in the laboratory. Four generations were reproduced in the laboratory, and a method for its rearing was established. The life cycle usually lasts 6?months, but under optimal laboratory conditions, it lasted from 2 to 4?months. Larvae were fed with Bradybaena similaris and Bulimulus tenuissimus snails since the beginning of the larval stage. This species was found to be easily adapted to environments under anthropic influence, such as urban areas and farms.