Characterization of compounds that induce symbiosis between sea anemone and anemone fish

The species-specific partnership between the sea anemone and anemone fish in many parts of the Indo-Pacific region is a well-known phenomenon. Chemicals secreted by the sea anemone to elicit symbiotic behavior of the fish have been studied for two host-guest pairs, Radianthus kuekenthali (sea anemone)-Amphiprion perideraion (anemone fish) and Stoichactis kenti-A. ocellaris. A new pyridinium compound, amphikuemin, which induces characteristic attracted swimming (toward the chemical stimulus) in A. perideraion, has been isolated from R. kuekenthali and characterized. Several other chemicals that elicit characteristic symbiotic movements have also been identified.     

Cnidocyte mechanoreceptors are tuned to the movements of swimming prey by chemoreceptors

Cnidocytes, the stinging cells of cnidarians, discharge nematocysts in response to physical contact accompanied by the stimulation of specific chemoreceptors. Cnidocytes in fishing tentacles of a sea anemone are now found to discharge nematocysts preferentially into targets vibrating at 30, 55, and 65 to 75 hertz. Moreover, in the presence of submicromolar concentrations of known chemosensitizers, such as N-acetylated sugars and mucin, these optima shift to 5, 15, 30, and 40 hertz, frequencies that correspond to the movements of swimming prey. Hence, chemoreceptors for these substances tune cnidocyte mechanoreceptors to frequencies that match the movements of the prey.     

海葵多肽类神经毒素的结构与药理学功能

海葵以其触手刺细胞中的毒液行使捕食和防御功能,其毒液中富含各种多肽类神经毒素,分子量为3—7kDa之间,分子序列中含多对二硫键以稳定其结构。海葵神经毒素以钠离子通道毒素和钾离子通道毒素为其主要成分,此外还发现有作用于其他离子通道的成分,此外,还有部分海葵毒素目前尚不清楚其分子靶标。不同类型的海葵毒素具有不同的空间结构。海葵毒素多肽的分子多样性使其成为动物毒素研究的一个重要分支,同时海葵多肽毒素对不同离子通道的特异性和高亲和性,使得它们成为神经生理学和药理学研究的一种重要工具。     

Reactivated triton-extracted models o paramecium: modification of ciliary movement by calcium ions

Triton-extracted models of Paramecium were reactivated to swim in solutions of adenosine triphosphate and magnesium ions. The cilia beat in the normal direction (toward the rear) when the calcium ion concentration was less than 10-(6)M, and they beat in the "reversed" direction (toward the front) when calcium ion concentration was raised above 10-(6)M. These results support the proposal that ciliary reversal, hence backward swimming, of live paramecia is mediated by an increased cytoplasmic calcium concentration around the ciliary system by calcium-dependent membrane responses to external stimuli.     

中华仙影海葵早期发育的初步研究

在生物进化研究中,海葵的胚胎和幼体是研究二侧对称动物进化祖先较理想的实验动物。以室内实验方法研究了中华仙影海葵的胚胎、浮浪幼虫及幼海葵的发生、发育过程,对各阶段的变化和形态特点进行了比较详细的描述,并比较了中华仙影海葵与其他3种海葵的早期发育,揭示了中华仙影海葵从性腺成熟到16触手幼海葵各个阶段的变态过程。     

黄海葵解剖学和主要器官组织学的研究

黄海葵Anthopleura xanthogrammica Berkly为二胚层动物,体形辐射对称,主要器官包括皮肤、触手、隔膜、消化道和生殖腺。消化道由口、口道和消化腔组成,无肛门;各器官的上皮组织均是由内皮肌细胞或外皮肌细胞组成,上皮中夹有大量的腺细胞;在其触手、隔膜丝及口道的上皮中还发现了3种结构不同的刺细胞(刺丝囊),分别行使不同的功能;生殖腺为滤泡型,由营养细胞和生殖细胞共同构成。此外,还探讨了海葵主要结构与功能的关系。     

仿生鱿鱼俯仰姿态下水动力学数值模拟

鱿鱼作为海洋高等软体动物,其软体特征与腕部特点为其机动性奠定了基础。为研究仿生鱿鱼软体触腕在不同俯仰角度下的弯曲特性,选择茎柔鱼(Dosidicus gigas)为仿生对象,建立仿生鱿鱼不同俯仰角度下的简化三维模型,并根据不同俯仰角度假设触腕不同弯曲特性。根据三维简化模型,采用数值模拟方法,分析比较仿生鱿鱼在不同俯仰姿态下与触腕弯曲下的水动力特性。研究认为:仿生鱿鱼采用软体触腕协调游动时,为其俯仰姿态的完成提供了有利的转矩,俯仰角最大为45°时其力矩系数达到-0.001 7,更有利于其高速游动时俯仰姿态的调整与游动方向的改变;仿生鱿鱼在完成俯仰姿态时可以通过改变腕部的弯曲程度,更及时高效地调整姿态与改变游动方向,且所需能耗较小。研究结果对仿生鱿鱼软体触腕的控制提供了依据与参考,同时为研究其高机动性游动行为与材料的选取奠定了基础。     

Recruitment in a sea anemone population: juvenile substrate becomes adult prey

Populations of the sea anemone Anthopleura xanthogrammica (Brandt) occur in tide pools and surge channels below intertidal mussel beds where they capture mussels dislodged by wave action and by sea star foraging. Dense concentrations of small juvenile anemones occur only within mussel beds and are probably the result of larval settlement or differential survival in that habitat. Areas experimentally cleared of anemones showed that recruitment was primarily by migrating juveniles and that the rate of immigration over a 2-year period was much higher in experimental removal areas near mussel beds than in those further away. Mussel beds thus function as an important juvenile habitat (refuge and nursery); juveniles later migrate downward and are then in a position to capture dislodged mussels and grow to adult size.     

Transamination of aminoalkylphosphonic acids with alpha ketoglutarate

Dialyzed homogenates prepared from Escherichia coli, Tetrahymena pyriformis, sea anemone (Anthopleura elegantissima), and mouse liver were tested for ability to transaminate 17 aminoalkylphosphonic acids with alpha-ketoglutarate. 2-Aminoethylphosphonic acid (2-AEP), which occurs naturally in Tetrahymena and anemone, was transaminated by these latter organisms more than any of the substances tested, but not by preparations from liver or E. coli. 3-Aminopropylphosphonic acid was transaminated by all preparations, but much less by Tetrahymena or anemone than was 2-AEP. 2-Amino-3-phosphonopropionic acid was transaminated by all preparations. 2-Amino-4-phosphonobutyric acid was transaminated by three of the preparations, but not by liver. Of the other 13 substances tested, the following gave positive results: DL-1,2-diaminoethylphosphonic acid with E. coli, DL-1,2-diaminoethylphosphonic and aminomethylphosphonic acids with Tetrahymena, DL-1-aminopropylphosphonic acid with anemone, and DL-1-aminoethylphosphonic and DL-1-aminobutylphosphonic acids with liver. The significance of these transaminations is discussed.     

底质和饵料投喂对中华仙影海葵生长影响的研究

以中华仙影海葵(Cereus sinensis Verrill)个体为实验对象,通过改变底质、投喂频次和投喂量等,探究底质和饵料投喂方式对中华仙影海葵个体生长的影响。实验结果表明,砂质底质和无底质培养对海葵个体生长影响差异不显著;培养密度33.3 ind/m2、50.0 ind/m2、66.7 ind/m2、88.3 ind/m2和100.0 ind/m2对海葵个体生长影响差异不显著。不同投饵频次和不同投饵量对中华仙影海葵个体生长影响差异显著。当投饵频次减少到4天一次时,海葵个体生长减慢,其口盘直径增长率为0.84%,而高频次投喂组1天一次、2天一次和3天一次海葵个体生长较快,其口盘直径增长率均在1.30%以上;当投喂饵料量控制在1.0 g/d以下,海葵生长趋于缓慢,其口盘直径增长率不足0.97%,而投饵量控制在大于1.5 g/d时,海葵个体口盘直径增长率大于1.25%。     

Sea anemone genome reveals ancestral eumetazoan gene repertoire and genomic organization

Sea anemones are seemingly primitive animals that, along with corals, jellyfish, and hydras, constitute the oldest eumetazoan phylum, the Cnidaria. Here, we report a comparative analysis of the draft genome of an emerging cnidarian model, the starlet sea anemone Nematostella vectensis. The sea anemone genome is complex, with a gene repertoire, exon-intron structure, and large-scale gene linkage more similar to vertebrates than to flies or nematodes, implying that the genome of the eumetazoan ancestor was similarly complex. Nearly one-fifth of the inferred genes of the ancestor are eumetazoan novelties, which are enriched for animal functions like cell signaling, adhesion, and synaptic transmission. Analysis of diverse pathways suggests that these gene "inventions" along the lineage leading to animals were likely already well integrated with preexisting eukaryotic genes in the eumetazoan progenitor.     

仿刺参β-actin基因的克隆及在各组织中的表达

参考海葵Nematoste Uavectensis在GenBank中的β-actin基因mRNA部分序列（XM_001630533）设计引物,对仿刺参Apostichopusjaponicus进行特异的PCR扩增,将扩增产物测序分析,再根据测序结果设计仿刺参专用β-actin引物ACT1／ACT2,对不同退火温度和循环次数条件下的该基因RT-PCR产物进行了对比。本研究中首次克隆了仿刺参的β-actin基因,为今后仿刺参目的基因表达的半定量分析研究奠定了基础。     

Optical imaging of neuronal populations during decision-making

We investigated decision-making in the leech nervous system by stimulating identical sensory inputs that sometimes elicit crawling and other times swimming. Neuronal populations were monitored with voltage-sensitive dyes after each stimulus. By quantifying the discrimination time of each neuron, we found single neurons that discriminate before the two behaviors are evident. We used principal component analysis and linear discriminant analysis to find populations of neurons that discriminated earlier than any single neuron. The analysis highlighted the neuron cell 208. Hyperpolarizing cell 208 during a stimulus biases the leech to swim; depolarizing it biases the leech to crawl or to delay swimming.     

Sea anemone neuromuscular responses in anaerobic conditions

The sea anemone Bunodosoma cavernata survives anoxic conditions for as long as 6 weeks. Whether or not oxygen is present, its neuromuscular responses are the same and the pulses of its nerve net have the same threshold size and shape. Bunodosoma cavernata buried in the sand during a low tide are exposed to anoxic conditions. Their neuromuscular responses in anaerobic conditions ensure protective withdrawal behavior should the need arise.     

A disulfide-linked collagenous protein of nematocyst capsules

The major protein component present in the capsule and thread of a sea anemone nematocyst consists of monomers of a collagen-like protein linked by disulfide bonds. Purified nematocyst capsules and threads are rich in hydroxyproline, and dissolved by disulfide reducing agents. Electrophoresis of the dissolved component on acrylamide gel results in a single detectable protein band.     

Temperature acclimation: improved sustained swimming performance in carp at low temperatures

At low temperatures, the reduction in mechanical power output of the aerobic muscle forces cold-blooded animals, such as carp, to recruit their rapidly fatiguing anaerobic fibers at relatively slow swimming speeds. Previous experimental data have suggested that changes in the biochemistry and morphology of the aerobic muscle during cold acclimation might increase its output of mechanical power. The present experiments show that, because of these changes, carp can swim faster at low temperature using only their aerobic muscle, which results in an increase in their sustainable swimming speed. By modifying their musculature, cold-blooded animals can achieve some independence from the effects of seasonal changes in environmental temperature.     

Biphasic feeding response in a sea anemone: control by asparagine and glutathione

Two phases of the feeding response in the sea anemone Anthopleura elegantissima are controlled by different chemical activators. Asparagine controls the contraction and bending of tentacles which bring food to the mouth; reduced glutathione controls ingestion of food once it has contacted the mouth. A complete feeding response occurs only when both chemical activators are present.     

Sonar Signals of the Sea Lion

Tape recordings were made of the underwater noises of captive sea lions swimming in a concrete pool at night. When approaching pieces of fish that were thrown into the water, the sea lions emitted trains of sound signals like those of the bat and the porpoise. A detailed analysis of these noises shows that they meet the criteria of a pulse-modulated sonar system and, in fact, reveal an amazing sophistication so far as echo ranging is concerned.     

Alarm Response of Diadema antillarum

Diadema antillarum possesses a sensitive escape response to juices of crushed conspecific sea urchins. Stimulation usually results in urchins moving rapidly downcurrent. Strong species specificity of the response suggests that it is an adaptation to reduce predation. Diadema antillarum also responds with a running response to contact with Cassis tuberosa, a known predator.     

Wave-making by whirligig beetles (gyrinidae)

Swimming whirligig beetles (Dineutes carolinus) either make no waves at all or make conspicuous circular or vee-shaped patterns of capillary waves. The beetle's swimming speed can be determined from these wave patterns (or lack of them). Capillary waves precede the beetle for several body lengths, and their reflections may help the beetle avoid solid objects by echolocation. The gravity waves produced by a beetle are always longer than the beetle's hull length. Hence the waves do not interact with the hull to impose an upper limit on speed as they do with conventional ships. Although the beetles swim at high speeds, they apparently do not hydroplane.