Selective loss of a family of gene transcripts in a hereditary murine cataract

The eye lens of the Fraser mouse contains a dominantly inherited cataract with reduced amounts of seven distinct but homologous gamma crystallins encoded by a family of gamma-crystallin genes. The results of experiments with cultured lenses, cell-free RNA translation, and Northern blot hybridization indicated a specific loss of the family of gamma-crystallin messenger RNA's in the Fraser mouse lens. Southern blot hybridization of genomic DNA's from normal and Fraser mice showed no differences in gamma-crystallin coding sequences.     

眼睛晶体在头足类生活史分析中的研究进展

头足类的眼睛晶体是除耳石、角质颚和内壳之外又一重要的硬组织,其形态结构稳定、易提取、易保存,记录了头足类的大量生物与生态学信息,是研究头足类生活史过程的有益补充。尽管眼睛晶体在年龄鉴定和微量元素分析方面相比耳石和角质颚没有优势,但是在稳定同位素分析方面优势明显。本研究中从眼睛晶体的尺寸、微结构、微量元素和稳定同位素等方面,回顾了其在头足类年龄、生长、摄食、栖息和洄游等基础生活史过程中的应用。综合分析认为,尽管眼睛晶体适合从时间序列上准确的分析头足类的生活史信息,今后的研究仍需要准确掌握眼睛晶体生长纹的周期性,在此基础上确定各层断面形成的确切时间、年龄,进而重建头足类的栖息、洄游和摄食等生活史信息。     

鱼类眼睛晶体信息分析与应用研究进展

眼睛晶体作为鱼类的硬组织之一,具有结构稳定、耐腐蚀、易获取的特性,其含有大量的蛋白质,蕴含着丰富的化学信息,并在鱼类的年龄鉴定中得到了一定程度的应用。近年来,随着生物地球化学技术的不断创新与进步,鱼类眼睛晶体的微量元素、稳定同位素信息也越来越受到国内外学者的重视。本文将依据国内外学者的研究成果,从眼睛晶体的直径与重量、微结构、微量元素和稳定同位素等方面,对鱼类的年龄鉴定、栖息环境重建、摄食生态的追踪等方面的应用进行综述,并通过分析鱼类眼睛晶体的组成成分与生长模式,比较眼睛晶体与其他组织做稳定同位素分析的优势,着重归纳总结了眼睛晶体碳氮稳定同位素在鱼类生活史信息,尤其在摄食生态、栖息环境重建等方面的研究方法、应用现状及发展前景,为以后开展相关的研究提供参考。     

Central role for the lens in cave fish eye degeneration

Astyanax mexicanus is a teleost with eyed surface-dwelling and eyeless cave-dwelling forms. Eye formation is initiated in cave fish embryos, but the eye subsequently arrests and degenerates. The surface fish lens stimulates growth and development after transplantation into the cave fish optic cup, restoring optic tissues lost during cave fish evolution. Conversely, eye growth and development are retarded following transplantation of a surface fish lens into a cave fish optic cup or lens extirpation. These results show that evolutionary changes in an inductive signal from the lens are involved in cave fish eye degeneration.     

Lizard Tail Autotomy: Function and Energetics of Postautotomy Tail Movement in Scincella lateralis

Handling of autotomized, thrashing and autotomized, exhausted tails of the lizard Scincella lateralis by mammals and snakes was tested to examine the function of postautotomy tail movement. Tail movement attracted a mammal's attack to the tail, permitting the lizard to escape and increased the time required for a snake to subdue a tail before swallowing it, increasing the lizard's escape time by 40 percent. Lactate concentrations of autotomized tails after movement were compared to those of intact tails after rest in S. lateralis, a species with a high rate of autotomized tail thrashing, and Anolis carolinensis, a species with a low rate of thrashing. Postautotomy movement increased tail lactate concentration in both species, but mean tail lactate concentration in S. lateralis was 60 percent higher than that in A. carolinensis, and a third higher than that reportedfor whole-body lactate content of the very mobile lizard Dipsosaurus dorsalis.     

Recruitment of enzymes as lens structural proteins

Crystallins, the principal components of the lens, have been regarded simply as soluble, structural proteins. It now appears that the major taxon-specific crystallins of vertebrates and invertebrates are either enzymes or closely related to enzymes. In terms of sequence similarity, size, and other physical characteristics delta-crystallin is closely related to argininosuccinate lyase, tau-crystallin to enolase, and SIII-crystallin to glutathione S-transferase; moreover, it has recently been demonstrated that epsilon-crystallin is an active lactate dehydrogenase. Enzymes may have been recruited several times as lens proteins, perhaps because of the developmental history of the tissue or simply because of evolutionary pragmatism (the selection of existing stable structures for a new structural role).     

External morphology and microstructure of the compound eye of fire ants, Solenopsis invicta Buren

The external morphology of the compound eye of the winged female and male Solenopsis invicta Buren and its microstructure in light and dark adaptations were observed using scanning electron microscopy and optical microscopy. The results indicated that the compound eye located on the lateral side of its head, is the a shape of a half ellipsoid and composed of approximately 510 ommatidia in the female, and a near hemisphere with about 805 ommatidia in the male. The ommatidium was made of a corneal lens, crystalline cone, 8 to 9 retinula cells and basement membrane. The cornea was a colorless, transparent and double convex lens. The crystalline cone, with an inverted cone shape, was approximately 14.50m long, formed by four equal parts, and surrounded by many pigment granules. The rhabdom beneath the crystalline cone, was about 75.00m long, with a thicker middle part and thinner ends. More pigment granules were scattered in the distal and proximal ends and less in the middle, and the basement membrane was on the most bottom area of the ommatidium. The primary pigment cells moved horizontally along the crystalline cone from its distal to proximal end during dark adaptation or moved reversely during light adaptation. There was no significant difference between the pigment granule distribution and the structure of the crystalline cone between female and male ommatidium under the same light or dark adaptation. It is concluded that the fire ant compound eye is an apposition eye, whose light-tuning mechanism is accomplished by the change of crystalline cone and the movement of the pigment cells.     

秘鲁外海茎柔鱼眼睛晶体微结构分析

分析从秘鲁外海采集的113尾茎柔鱼(Dosidicus gigas)眼睛晶体的微结构,并对其生长纹的周期性进行验证,结果显示:眼睛晶体由前后两个部分组成,直径最大处所处的平面为赤道面,记录了晶体中所有的生长纹,生长带周期性明显,每条生长带由明、暗相间的两条同心的生长纹组成。由晶体核心至边缘,相邻生长纹间隔逐渐变小,没有明显的过渡区。晶体平均直径为7 mm,且平均每天生长7条生长纹。通过配对样本t检验,发现眼睛晶体生长纹与耳石日龄之间有很大的差异性(P0.05)。样本晶体生长纹A与晶体直径D呈指数关系(D=6.88e~(0.000 09A),n=113,R~2=0.578 1),与胴长ML也呈指数关系(L_(ML)=216.25e~(0.000 2A),n=113,R~2=0.463 2)。研究结果表明,茎柔鱼眼睛晶体生长纹不具有日周期性,但可将其作为个体生长分析的指标,为我国学者开展头足类年龄生长研究提供重要的基础文献。     

Anolis carolinensis: Effects of Feeding on Reaction to Aposematic Prey

During a 15-day experiment, green anoles, Anolis carolinensis, were: (i) presented with one of two aposematic insects, Oncopeltus fasciatus or Photinus pyralis, during days 4, 6, and 8; (ii) maintained on one of four different food levels during days 9-14; and (iii) presented with the original model on day 15. Lizards on low rations tended to capture more Photinus on day 15 than did anoles on higher rations. No such correlation was observed with Oncopeltus.     

Calcium requirement for melanophore-stimulating hormone action on melanophores

The calcium ion is specifically required for the action of melanophorestimulating hormone on melanosome dispersion within lizard (Anolis carolinensis) melanophores in vitro. The response to this hormone is directly related to the concentration of the Ca(2+) ion. Lithium, choline, rubidium, and cesium will replace the sodium and potassium of Ringer solution if Ca(2+) is present. Calcium ions are not required for melanosome dispersion itself, since theophylline or dibutyryl cyclic adenosine monophosphate reversibly darkens lizard skins in the absence of calcium.     

Gating of retinal transmission by afferent eye position and movement signals

Vision in most vertebrates is an active process that requires the brain to combine retinal signals with information about eye movement. Eye movement information may feed forward from the motor control areas of the brain or feed back from the extrinsic eye muscles. Feedback signals elicited by passive eye movement selectively gate retinal outflow at the first relay, the dorsal lateral geniculate nucleus. The gating predominantly facilitates retinogeniculate transmission immediately after eye movement and inhibits transmission when a new steady-state eye position is achieved. These two gating effects are distributed in a complementary fashion across the dorsal lateral geniculate nucleus such that the spatiotemporal activity profile could contribute to object detection and localization.     

Excitability changes in cat lateral geniculate cells during saccadic eye movements

The excitability of lateral geniculate cells to orthodromic volleys decreased during saccadic eye movements. This decrease was caused by retinal impulses generated by a quick displacement of the image of the visual field associated with eye movements. This may be a mechanism for saccadic suppression.     

Discharge of frontal eye field neurons during eye movements in unanesthetized monkeys

Single unit activity was recorded from the frontal eye fields (area 8) in unanesthetized monkeys seated in a primate chair with the head restrained. The frontal eye field units were identified by antidromic response to stimulation of the cerebral peduncle. The findings indicate that most of the neurons discharge only after initiation of eye movements. These cells showed steady discharge when the eyes were immobile and oriented in a specific direction.     

Limulus lateral eye: properties of receptor units in the unexcised eye

Single receptor units in the compound eye of the horseshoe crab were illuminated, and their impulse discharges were recorded without removing the eye from the animal. The receptors were spontaneously active in darkness and responded without saturation over a light intensity range of 10(10) to 1. When the eye was excised, the receptors did not discharge in darkness and had an intensity range of 10(5) to 1, as is usually found. Experiments show that these and other differences result from cutting off the blood supply to the eye when it is excised. In addition, the range and shape of the intensity characteristic suggest that more than one receptor mechanism encodes light intensity in this eye.     

Oncogenesis of the lens in transgenic mice

Neoplastic tumors of the ocular lens of vertebrates do not naturally occur. Transgenic mice carrying a hybrid gene comprising the murine alpha A-crystallin promoter (-366 to +46) fused to the coding sequence of the SV40 T antigens developed lens tumors, which obliterated the eye cavity and even invaded neighboring tissue, thus establishing that the lens is not refractive to oncogenesis. Large-T antigen was detected early in lens development; it elicited morphological changes and specifically interfered with differentiation of lens fiber cells. Both alpha- and beta-crystallins persisted in many of the lens tumor cells, while gamma-crystallin was selectively reduced. Accessibility, characteristic morphology, and defined protein markers make this transparent epithelial eye tissue a potentially useful system for testing tumorigenicity of oncogenes and for studying malignant transformation from its inception until death of the animal.     

Oceili: a celestial compass in the desert ant cataglyphis

In addition to multifaceted lateral compound eyes, most insects possess three frontal eyes called ocelli. Each ocellus has a single lens, as does the vertebrate eye. The ocelli of some flying insects, locusts and dragonflies, have been shown to function as horizon detectors involved in the visual stabilization of course. In a walking insect, the desert ant Cataglyphis, it is now shown that the ocelli can read compass information from the blue sky. When the ant's compound eyes are occluded and both sun and landmarks are obscured, the ocelli, using the pattern of polarized light in the sky as a compass cue, help in guiding the ant back home.     

橘小实蝇成虫复眼结构及感光机制

【目的】研究橘小实蝇Bactrocera dorsalis成虫复眼外部形态、内部显微结构和光感受机制。【方法】利用扫描电镜观察橘小实蝇成虫复眼外部形态,组织切片研究成虫复眼内部显微结构及在不同光环境下小眼结构的变化。【结果】橘小实蝇成虫复眼位于头部两侧,正面观呈半球形,表面光滑平坦;小眼间隙有感觉毛,单个小眼由角膜、晶锥、网膜细胞及其特化的视杆、基膜等构成,晶锥、视杆周围和色素细胞内均含有大量的色素颗粒。不同单色光处理后,小眼内的附属色素细胞色素颗粒沿小眼纵轴移动。白光、绿光和黄光处理后,附属色素细胞色素颗粒沿小眼纵轴均匀分布;紫光、蓝光和红光处理后,附属色素细胞色素颗粒主要集中在视网膜细胞远端和角膜的近端。【结论】橘小实蝇雌、雄成虫复眼在外形和内部结构上无差异,均属于并置像眼,屏蔽色素颗粒的移动是其复眼适应外界光环境变化的重要机制,该研究结果为筛选橘小实蝇成虫敏感光波并对其进行灯光诱杀提供了理论依据。     

Scanpaths in eye movements during pattern perception

Subjects learned and recognized patterns which were marginally visible, requiring them to fixate directly each feature to which they wished to attend. Fixed "scanpaths," specific to subject and pattern, appeared in their saccadic eye movements, both intermittently during learning and in initial eye movements during recognition. A proposed theory of pattern perception explains these results.     

Spacing differentiation in the developing Drosophila eye: a fibrinogen-related lateral inhibitor encoded by scabrous

In the development of multicellular organisms a diversity of cell types differentiate at specific positions. Spacing patterns, in which an array of two or more cell types forms from a uniform field of cells, are a common feature of development. Identical precursor cells may adopt different fates because of competition and inhibition between them. Such a pattern in the developing Drosophila eye is the evenly spaced array of R8 cells, around which other cell types are subsequently recruited. Genetic studies suggest that the scabrous mutation disrupts a signal produced by R8 cells that inhibits other cells from also becoming R8 cells. The scabrous locus was cloned, and it appears to encode a secreted protein partly related to the beta and gamma chains of fibrinogen. It is proposed that the sca locus encodes a lateral inhibitor of R8 differentiation. The roles of the Drosophila EGF-receptor homologue (DER) and Notch genes in this process were also investigated.     

日本蟾蜍皮肤claudin-4 cDNA的克隆与序列分析

为研究日本蟾蜍Bufo japonicus formosus皮肤中多肽类有效成分,通过菌落聚合酶链式反应（PCR）对日本蟾蜍皮肤cDNA质粒文库进行筛选,克隆到2条claudin-4全长cDNA序列（GenBank登录号为JX481975和JX481976）,并对它们进行生物信息学分析。日本蟾蜍claudin-4的2条cDNA全长分别为1 707 bp和1 697 bp,开放阅读框均为630 bp,其中虽有5个碱基不同,但编码的209个氨基酸完全相同。两者的5端非翻译区域序列长度不同,前者为50 bp,后者为41 bp,3端非翻译区域则分别为1 027 bp和1 026 bp。氨基酸序列同源性分析显示,日本蟾蜍claudin-4与非洲爪蟾Xenopus laevis的同源性最高,为88％,与其他7种动物的同源性介于65%~72%。克隆到2条日本蟾蜍claudin-4基因的cDNA序列,为今后研究日本蟾蜍Claudin-4 生物学功能奠定了基础。图5参21