萤光虫复眼光学模型重叠成象的研究与模拟

以北京萤光虫复眼结构与生理参数为依据,基于已知的梯度折射率透镜特征,对复眼的整个光学系统进行模型化,模型的尺寸与折射率分布依据实际晶锥的测量值,通过对模型复眼的光线追迹,证明北京萤光虫复眼是一个折射重叠型复眼,重叠孔径以内入射的平行光线在视网膜水平形成一半宽度为一定值的模糊圈,利用计算机光线追迹模拟了复眼的重叠成象过程,随着象平面与晶锥近端距离的增加,信号光线的数目也逐渐增加,信噪比逐渐提高,在视     

萤火虫复眼光学模型重叠成象的研究与模拟

以北京萤火虫复眼结构与生理参数为依据,基于已知的梯度折射率透镜特征,对复眼的整个光学系统进行模型化.模型的尺寸与折射率分布依据实际晶锥的测量值.通过对模型复眼的光线追迹,证明北京萤火虫复眼是一个折射重叠型复眼.重叠孔径以内入射的平行光线在视网膜水平形成一半宽度为一定值的模糊圈.利用计算机光线追迹模拟了复眼的重叠成象过程,随着象平面与晶锥近端距离的增加,信号光线的数目也逐渐增加,信噪比逐渐提高,在视网膜水平达到最大值.     

棉铃虫蛾复眼的微细结构及其区域性差异

用电子显微镜观察棉铃虫蛾复眼的微细结构及其区域性差异。此复眼具有小网膜细胞柱的透明带。每个小眼包括一个外凸内平的角膜,一个晶锥,四个形成晶锥、晶束的晶锥细胞和两个围绕着晶锥的主虹膜细胞,六至八个小网膜细胞和一个基细胞。晶锥末端有一短小固定的晶束。小网膜细胞柱远侧中央有似微绒毛结构的视杆束。每个小眼被六个附色素细胞围绕。 微细结构的区域性差异:1.背方小眼视杆中段横切面近似矩形,主要由六个微绒毛平行排列的三角形视小杯组成,整个视杆包含两个互相垂直的微绒毛轴;腹方、前方、后方和侧方区域的小眼视杆中段横切面为风扇形,“V”字形视小杆内微绒毛排列不平行;2.前方区域小眼视杆中段的横切面要比后方大;3.前方、腹方区域内,有的相邻小眼的小网膜细胞柱互相连结,背方、后方区域未观察到这一现象。     

灰茶尺蠖成虫复眼的超微结构及其明暗适应中的变化

【目的】明确灰茶尺蠖Ectropis grisescens成虫复眼的超微结构及其明暗适应中的变化,探究其调光机制。【方法】采用超景深显微镜测定了灰茶尺蠖成虫复眼的小眼数量、间角、直径和曲率半径等外部参数,并通过组织切片、光学显微镜和透射电子显微镜等技术观察了复眼的内部超微结构;通过光学显微镜观察了灰茶尺蠖成虫复眼在明暗环境中分别适应2 h后晶锥结构及色素颗粒的位置变化。【结果】灰茶尺蠖成虫复眼呈半球形,雌、雄虫单个复眼分别有2 502±105和3 123±78个小眼。小眼自远端至近端由角膜、晶锥、透明区构成的屈光层和由15个视网膜细胞构成的感光层组成。2个初级色素细胞包裹着晶锥,自角膜近端延伸至视网膜细胞核区的远端;每个小眼外围由6个次级色素细胞围绕,自角膜近端延伸至基膜;在透明区内14个视网膜细胞聚集成束(非感杆束),远端与晶锥束末端连接,在感光层内形成闭合型感杆束,延伸至第15个视网膜细胞(基部视网膜细胞)。在明暗适应时,灰茶尺蠖复眼的晶锥细胞间出现开闭,色素颗粒进行纵向位移,以适应外界的光强度的变化。【结论】灰茶尺蠖成虫复眼属于重叠像眼,感杆束为“14+1”模式;屏蔽色素颗粒的移...     

柚木野螟成虫复眼外部形态和超微结构观察

【目的】柚木野螟Eutectona machaeralis主要取食危害珍贵树种柚木。本研究旨在观察研究柚木野螟成虫复眼的形态、组织结构和超微结构,分析其复眼结构特征,为更好了解该物种复杂的视觉行为与感光、趋光机制的关系奠定基础。【方法】运用光学显微镜以及扫描和透射电子显微镜技术观察了柚木野螟成虫复眼的形态、组织结构和超微结构。【结果】柚木野螟成虫复眼着生于头部触角基部,呈椭球形,属对称性复眼。雌、雄成虫复眼分别有2 300~2 755和1 950~2 316个小眼。小眼呈正六边形,表面密被角膜乳突,间隙偶有感觉毛。每个小眼由1个角膜、4个晶锥细胞、1对初级色素细胞,6个次级色素细胞、不同水平面分布的12个视网膜细胞和基膜等组成。沿小眼纵轴11个视网膜细胞的向心侧细胞膜特化成细丝状微绒毛,形成放射状排列的视小杆,组合呈融合型视杆;第12个视网膜细胞位于小眼基部。基膜上方,视网膜细胞和次级色素细胞末端膨大,以轴突形式穿过基底膜。【结论】柚木野螟复眼为典型的重叠像眼,雌、雄成虫小眼排列方式及内部结构无明显差异,但雌、雄虫小眼数量和大小具有明显的性二型现象。     

大兴安岭植被生物量的ALOS PALSAR估算

利用野外实测调查数据,系统分析了ALOS PALSAR L波段HH(L-HH)极化数据与大兴安岭地区森林各成分参数的关系,并采用简单线性模型、指数模型和加入地理因子模型建立森林生物量的估算模型进行最优反演.结果表明:后向散射系数与树木地上部分总生物量相关性最大,其次是干生物量,L-HH数据可以用来反演正确的树木地上部分总生物量.3种模型中,加入地理因子模型降低了植被生物量估算的误差,精度达0.851,反演结果与实际相符.在41.5°入射角L-HH极化数据下,大兴安岭塔河林业局和阿木尔林业局的森林生物量饱和点在15.4 kg·m-2.     

SDS-PAGE法测定His-tag融合蛋白分子量产生偏差的原因

Ｈｉｓｔａｇ／ＮｉＮＴＡ系统是新发展起来的一个亲和纯化重组蛋白的有用工具,现常用于基因编码产物的特性研究中。ＳＤＳＰＡＧＥ是实验室测定蛋白质分子量通常采用的方法,而许多实验室用此方法检测Ｈｉｓｔａｇ融合蛋白时却常发现测得的分子量偏大,产生偏差的原因尚未阐明。为弄清这一问题,本实验室在研究一个Ｈｉｓｔａｇ融合蛋白Ｐ７３Ｈｉｓ时,首先用ＳＤＳＰＡＧＥ法测得其分子量确实比理论计算值大,然后对其进行Ｃ末端氨基酸顺序测定、电喷雾质谱分析,结果证实其实际分子量与理论值一致。酶切去除包括Ｈｉｓｔａｇ在内的部分肽段使ＳＤＳＰＡＧＥ法测量蛋白分子量的偏差大大降低,证实Ｈｉｓｔａｇ确实是造成偏差的原因之一。推测由于Ｈｉｓｔａｇ中的碱性氨基酸的作用造成蛋白在ＳＤＳＰＡＧＥ中迁移变慢,而导致偏差。这一现象值得引起有关研究者的注意。     

不同地域小稻蝗mtDNA部分序列及其相互关系

测定了9个不同地理区域的小稻蝗Oxya intricata (Stal)共33个个体的线粒体DNA (mtDNA)细胞色素b基因部分序列,比较其同源性,计算核苷酸组成,并用瘤锥蝗科的曲尾似橄蝗Pseudomorphacris hollisi和斑腿蝗科的芋蝗Gesonula punctifrons作外群构建NJ分子系统树。在获得的小稻蝗432 bp的序列中, A+T约占70.3%,其中30个核苷酸位点存在变异(约占所测核苷酸的6.9%),有5个位点引起了氨基酸的变异。就每个氨基酸密码子来看,第3位点的A+T含量较高,达90.4%。由NJ树显示,小稻蝗mtDNA 细胞色素b序列不同单倍型之间有一定的分歧,形成不同的簇类关系,其分枝与地理分布没有直接的对应关系,但总体上看,这种簇类关系基本上呈平行分布,没有明显的地域性差别。     

少棘蜈蚣毒腺RACE cDNA文库的构建及β-actin基因的克隆与序列分析

运用SMART技术首次构建了少棘蜈蚣(Scolopendrasubspinipes)毒腺cDNA文库。经琼脂糖电泳检测,文库所含全长cDNA主要分布在5 0 0bp以上,大于2 0 0 0bp的区域尚有很长拖尾,中间有几条高丰度mRNA亮带。以此文库为模板,通过5′RACE(RapidamplificationofcDNAends,快速扩增cDNA末端)方法获得了细胞质肌动蛋白βactin基因5′末端5 98bp片段,其中包括开放阅读框5 46bp ,编码1 82个氨基酸。将该基因片段推导的氨基酸序列通过BLAST软件与蛋白质公共数据库Swissprot比对,发现与蜜蜂(Apismellifera)的βactin基因同源性高达96% ,说明本实验所构文库质量完全可以满足用RACE方法进行功能基因的cDNA克隆。通过基于双参数模型的NJ法对部分动物βactin基因进行系统重建,较好地反映了这些动物的系统发生关系。     

甘油醛-3-磷酸脱氢酶与辅酶类似物ATP及底物磷酸结合特性的晶体学研究

气相扩散共晶生长法培养出Ｐ．ｖｅｒｓｉｃｏｌｏｒ龙虾肌ＡＴＰ－Ｄ－甘油醛－３－磷酸脱氢酶（ＡＴＰ－ＧＡＰＤＨ）的晶体。用同步辐射Ｘ光源－磷光储屏－Ｗｅｉｓｓｅｎｂｅｒｇ照相机系统收集了一套２．０分辨率的衍射数据。用同晶差值傅立叶法解析了其结构。精化后的结构模型最终Ｒ因子为０．１９７,与标准键长、键角的均方根偏差为０．０１６°和３．２０°。ＰｖＡＴＰ－ＧＡＰＤＨ结构总体上和Ｐｖａｐｏ－ＧＡＰＤＨ相似。ＡＴＰ分子的占有率较低,并表现出一定程度的无序性,提示ＡＴＰ与酶蛋白结合的稳定性较低,表明ＮＡＤ＋的尼克酰胺核苷部分与蛋白质分子的作用在辅酶与蛋白质的稳定结合中起关键作用。ＡＴＰ－ＧＡＰＤＨ中每个亚基只有一个磷酸结合位点（Ｐｉ）。认为无机磷酸结合位点Ｐｉ的形成不依赖于ＮＡＤ＋,而底物磷酸结合位点ＰＳ的形成则依赖于ＮＡＤ＋的存在。     

Ultrastructure of the eye of a euphausiid crustacean

The compound eye of the Antarctic euphausiid Euphausia superba is a spherical clear zone eye. The dioptric system consists of a hexagonally-faceted cornea, two corneagenous cells, two crystalline cone cells which form the bipartite crystalline cone, and two accessory cone cells. The dioptric system of each ommatidium is separated from that of adjacent ommatidia by six distal pigment cells and a basement membrane. The proximal tip of the crystalline cone is cupped by the distal ends of the seven retinula cells whose nuclei are arranged in a staggered array slightly distal to the middle of the clear zone. In the distal half of the clear zone, each narrow retinula cell column is surrounded by large proximal extensions of the six distal pigment cells. The pigment cells narrow more proximally and terminate at the proximal basement membrane. A specialized axial channel complex extends from the crystalline cone through the clear zone, and is continuous with a conical refractive element which caps the distal end of the rhabdom. The rhabdom is fused, and made up of alternating highly birefringent layers of orthogonally-oriented microvilli. It is surrounded by a narrow extra-cellular space which is continuous with the distal refractive element and a second conical refractive element at the proximal end of the rhabdom.     

Structure and functional aspects of the scotopic compound eye of the sugarcane borer moth

Morphology and functional aspects of the scotopic compound eye of the moth Diatraea saccharalis, studied using light and electron microscopy, is presented. An ommatidium is composed of a laminate corneal lens, four Semper cells, a refractive cone, two primary pigment cells, six screening pigment cells, a crystalline tract that functions as an optical waveguide, and six to eight sensory retinular cells. Accessory light regulators consist of screening pigment cells that, in the dark-adapted position, increase receptor sensitivity by permitting light rays to cross over to adjacent ommatidia and specialized tracheal regions that enhance sensitivity by reflecting light back toward sensory receptors.     

大草蛉成虫复眼的外部形态及其显微结构

用扫描电镜和光学显微镜观察了大草蛉Chrysopa pallens Ramber成虫复眼的外部形态及明、暗适应和性别对其显微结构的影响。结果发现：（1）其复眼呈半球形,位于头部两侧,略成“八”字形排列,单个复眼约由3 600个小眼组成,最前和最后小眼之间的夹角约为180°,最上和最下小眼之间的夹角约200°;（2）小眼主要由角膜、晶锥和6～8个小网膜细胞、基膜组成,外围环绕有2个初级虹膜色素细胞和6个次级虹膜色素细胞,基膜处有色素颗粒分布;（3）暗适应时,晶锥开裂程度较大,远端5～7个网膜细胞核向远端移动,与晶锥近端相接或接近,次级虹膜色素颗粒亦向远端移动包围晶锥;明适应时,晶锥开裂程度小或闭合,远端网膜细胞核向近端移动,透明带显现,大部分次级虹膜色素颗粒亦向近端移动分布在小网膜细胞柱周围,包被透明带;（4）在相同的明、暗适应下,雌、雄成虫复眼的显微结构无明显差异。结果表明大草蛉复眼为透明带明显的重叠象眼,其小眼不但具有次级虹膜色素颗粒纵向移动的常规调光机制,还存在晶锥开闭、远端网膜细胞核移动和基膜色素颗粒纵向扩散的调光新机制。     

The compound eye of<Emphasis Type="Italic"> Scutigera coleoptrata</Emphasis> (Linnaeus, 1758) (Chilopoda: Notostigmophora): an ultrastructural reinvestigation that adds support to the Mandibulata concept

The lateral compound eye of Scutigera coleoptrata was examined by electron microscopy. Each ommatidium consists of a dioptric apparatus, formed by a cornea and a multipartite eucone crystalline cone, a bilayered retinula and a surrounding sheath of primary pigment and interommatidial pigment cells. With reference to the median eye region, each cone is made up of eight cone segments belonging to four cone cells. The nuclei of the cone cells are located proximally outside the cone near the transition area between distal and proximal retinula cells. The connection between nuclear region and cone segment is via a narrow cytoplasmic strand, which splits into two distal cytoplasmic processes. Additionally, from the nuclear region of each cone cell a single cytoplasmic process runs in a proximal direction to the basement membrane. The bilayered rhabdom is usually made up of the rhabdomeres of 9–12 distal retinula cells and four proximal retinula cell. The pigment shield is composed of primary pigment cells (which most likely secrete the corneal lens) and interommatidial pigment cells. The primary pigment cells underlie the cornea and surround, more or less, the upper third of the crystalline cone. By giving rise to the cornea and by functioning as part of the pigment shield these pigment cells serve a double function. Interommatidial pigment cells extend from the cornea to the basement membrane and stabilise the ommatidium. In particular, the presence of cone cells, primary pigment cells as well as interommatidial pigment cells in the compound eye of S. coleoptrata is seen as an important morphological support for the Mandibulata concept. Furthermore, the phylogenetic significance of these cell types is discussed with respect to the Tetraconata.     

Geometrical optics of a galatheid compound eye

The eyes of galatheid squat lobsters (Munida rugosa) are shown to be of the reflecting superposition type. In the dark-adapted state corneal lenses focus light at the level of the rhabdoms and light from more than 1000 facets is redirected to the superposition focus by the reflecting surfaces of the crystalline cones. When the eye is light adapted, apposition optics are used. In this state paraxial light is focused by the corneal lens and the parabolic proximal end of the cone onto the distal end of a rhabdomeric lightguide. The latter transmits light across the clear zone to the rhabdom layer. In the dorsal part of the eye the individual ommatidia become progressively shorter until the cones and rhabdoms are no longer separated by a clear zone. Although formerly considered to be developing ommatidia, they are shown to be retained specifically for scanning the downwelling irradiance.Abbreviations RI refractive index - SEM scanning electron microscope     

Retina and dioptric apparatus of the dung beetle Euoniticellus africanus

Retinal fine structure and optics of the eye of the dung beetle Euoniticellus africanus have been studied and compared with those of three other scarabaeid beetles: Repsimus manicatus, Anoplognathus pallidicollis and Sericesthis geminata. The eye of Euoniticellus, in common with that of the other three species, possesses a dioptric system in which light first passes through a thick optically homogeneous cornea, and then enters a non-homogeneous crystalline cone. The lens cylinder properties of the latter cause the light rays to become partially focused across the clear-zone upon the rhabdom layer. Rays traced through a large scale drawing of the eye, with refractive indices measured for each component, predict an acceptance angle of approximately 26°. Since no significant aperture changes, lengthening of crystalline thread, cell or pigment migrations appear to be associated with dark/light adaptation, the eye may be assumed to be permanently poorly focused. In optomotor experiments the beetles did not show their characteristic antennal following response to black and white stripes when the latter had repeat periods of <30°. Structurally the eye of Euoniticellus differs markedly from that of other scarabaeids. It is totally divided into dorsal and ventral eye which are of a different size (the dorsal eye is smaller), but whose structural organization is basically the same. Principal pigment cells (they do not fully surround the cone) as well as accessory pigment cells (they accompany the retinula cells in an extraordinarily regular fashion as far as to the basement membrane) exhibit some unusual features. On the proximal side of the clear-zone, at a level where all retinula cell membranes form complex meanders and convolutions, cell 1 is the first to possess a rhabdomere. In it, all microvilli run parallel. This rhabdomere becomes part of the rectangular proximal rhabdom over the upper 20% of its length. Below this level the rhabdom consists of 6 rhabdomeres, but throughout its length microvilli are oriented in 2 orthogonal directions. It is thought that polarization sensitivity in dung beetles generally is related to the rhabdom organization described for Euoniticellus. An eighth (basal) cell is present in each ommatidium, but it lacks a rhabdomere. A tracheal tapetum is not developed. Finally, the point is made not to regard all different eye structures in insects as perfect adaptations to a particular environment or way of living, for specializations of photoreceptors may either follow, parallel or precede any ecological adaptation.     

The microanatomy of the compound eye of Munida irrasa (Decapoda: Galatheidae)

The compound eye of Munida irrasa differs in several respects from the typical decapod eye. The proximal pigment is found only in retinula cells. The eccentric cell is extremely large and expanded to fill the interstices of the crystalline tract area; thus, a typical "clear-zone" is absent. Six retinula cells course distally to screen two sides of the crystalline cone. There are approximately 12,500 ommatidia in each compound eye. There are several similarities to the typical decapod eye. Each ommatidium is composed of a typical cornea, corneagenous cells, crystalline cone cells, crystalline cone, crystalline cone tract and eight retinula cells. Distal pigment cells are present and surround the crystalline cone. The distal processes of the retinula cells also contain pigment. The retinula cell processes penetrate the basement membrane as fascicles composed of processes from adjacent retinulae.     

Mosquito eye design: conical rhabdoms are matched to wide aperture lenses

Night-active mosquitoes have photopigment-containing rhabdoms that take the form of a wide hollow cone, with the distal apex at the focus of the ommatidial lens. It is shown geometrically, and with the aid of a gelatin model, that such a structure can trap light over an angle of up to 60 deg, roughly equal to the width of the cone of light provided by the lens. This gives a gain in light-gathering power of up to nine times that of the more usual cylinder-shaped rhabdom with an acceptance angle of less than 25 deg.