草原沙蜥顶眼组织结构的半薄切片观察

草原沙蜥顶眼的角膜是由位于顶眼部位的皮肤特化形成，皮肤细胞色素消失，外表面的立方形细胞变为扁平细胞，其下的基质逐渐增厚，纤维增多，透明成角膜。晶状体与角膜紧密相贴，由交错排列的的几层柱状细胞组成，视网膜和晶状体相连，由感光细胞，色素细胞和神经节细胞组成，在由晶状体和视网膜围成的眼腔中，有玻璃体样结构分布，偶见有散在的细胞位于玻璃体样结构中。     

Molecular identification of a retinal cell type that responds to upward motion

The retina contains complex circuits of neurons that extract salient information from visual inputs. Signals from photoreceptors are processed by retinal interneurons, integrated by retinal ganglion cells (RGCs) and sent to the brain by RGC axons. Distinct types of RGC respond to different visual features, such as increases or decreases in light intensity (ON and OFF cells, respectively), colour or moving objects. Thus, RGCs comprise a set of parallel pathways from the eye to the brain. The identification of molecular markers for RGC subsets will facilitate attempts to correlate their structure with their function, assess their synaptic inputs and targets, and study their diversification. Here we show, by means of a transgenic marking method, that junctional adhesion molecule B (JAM-B) marks a previously unrecognized class of OFF RGCs in mice. These cells have asymmetric dendritic arbors aligned in a dorsal-to-ventral direction across the retina. Their receptive fields are also asymmetric and respond selectively to stimuli moving in a soma-to-dendrite direction; because the lens reverses the image of the world on the retina, these cells detect upward motion in the visual field. Thus, JAM-B identifies a unique population of RGCs in which structure corresponds remarkably to function.     

显微／望远两用镜光学系统设计

设计了一种新型的显微／望远两用镜,讨论了此两用镜的光学系统设计方法案和光学系统设计方案和光学系统各结构参数,对所得的象差曲线结果进行了分析,给了一个此光学系统的结构参数实例和产品外形轮廓。     

用电镜测定银簿膜的厚度

本文详细讨论了利用电镜测定银薄膜厚度的原理和方法。主要内容有，电子对银散射截面的计算和薄膜厚度与电子束的相对电流密度关系的计标。     

小白鼠眼的形态发生的研究

从小白发产胚胎第８ｄ形成视泡开始到发育为成体的眼为止，详细观察和描述了其眼的形态发育变化，实验以视网膜、晶体和角膜的发育为主。结果表明：视网膜的发育从胚胎第８ｄ视泡出现开始，在胚胎第９．５ｄ分化为２层，第１１．５ｄ分化为４层，刚出生时分化为６层，成年已分化完全，具完整的１０层结构；晶体的形态发生经历了晶体板（第９．５ｄ）、晶体凹（第１０ｄ）、晶体囊（第１０．５ｄ）、初级晶体纤维（第１１．５ｄ）及次     

GAP-43在锦鲤荒漠沙蜥和雉鸡视网膜内分布的免疫组化研究

GAP-43具有多种功能,主要与神经元轴突的生长、再生、神经递质的释放及膜泡的吞噬有关.本研究用免疫组织化学的方法观察了正常成年锦鲤、荒漠沙蜥和雉鸡视网膜内GAP-43分布.结果显示GAP-43主要分布在内网层,另外,在内核层、外网层、光感受器细胞层因动物不同也呈现不同的分布特点,而在节细胞层中3种动物均未发现GAP-43阳性染色.在锦鲤视网膜中GAP-43主要分布在内网层和内核层的无长突细胞;在荒漠沙蜥视网膜中GAP-43主要分布在内网层和外网层,在雉鸡视网膜中GAP-43主要分布在内网层、外网层、外核层和光感受器外节,其中在雉鸡视网膜外核层和光感受器外节中发现阳性分布是在脊椎动物此层发现GAP-43的首次报道.     

激光共焦扫描显微镜运动控制系统设计

概述了激光共焦扫描显微镜的系统结构,以基于DSP技术的运动控制器构建其运动控制系统,详细介绍基于DSP的运动控制系统的构成.该系统采用工控机 运动控制器的双CPU结构.在软件设计上采用友好的人机界面,把系统任务按实时性和非实时性分别分配给上下位机完成.下位机完成位置控制和速度控控制,上位机实现非实时的多任务功能.     

Myxococcus xanthus spore coat protein S may have a similar structure to vertebrate lens beta gamma-crystallins

The Gram-negative bacterium Myxococcus xanthus has a complex life cycle during which large amounts of a protein of relative molecular mass (Mr) 19,000, known as protein S, are assembled into a spore surface coat by a process that specifically requires calcium ions. The gene for protein S has been cloned and the DNA sequence shows that the gene product is composed of four internally repeated homologous sequences, each 40 amino acids long. Although protein S resembles calmodulin both in its internally duplicated structure and its ability to bind calcium, it apparently has a beta-sheet secondary structure rather than the helix-loop-helix motifs that characterize the calmodulin family. We now show that protein S has a striking homology with the beta- and gamma-crystallins of the vertebrate eye lens which are beta-sheet proteins with internally duplicated structures. This implies that the beta- and gamma-crystallins evolved from already existing proteins, whose ancestors occurred in the prokaryotes. The biological function of protein S, as a closely packed, stable protein in a relatively dehydrated environment, has implications for the functions of crystallins, which are found closely packed in the lens fibre cells, where their stability is essential for maintenance of transparency.     

Squid major lens polypeptides are homologous to glutathione S-transferases subunits

The eye lenses of cephalopods and vertebrates evolved relatively recently and by independent routes. They provide a good experimental model for the study of convergent evolution at the protein level. One proposal is that pre-existing proteins were recruited as structural eye lens proteins during evolution. This has been confirmed for the vertebrate eye lens structural proteins, or crystallins, which have been intensively studied. Despite the limited information about cephalopod eye lenses, it has been suggested that glutathione S-transferases (GSTs) are a possible evolutionary ancestor of the squid major lens proteins. Recently, the N-terminal sequence of the squid major lens protein was shown to be 55% homologous with that of the Ya subunit of the rat GST. Here, we demonstrate that the squid major lens polypeptides are encoded by a gene family of at least three members. We characterize two cDNAs corresponding to these genes and show they probably either are GST subunits themselves, or share an evolutionary ancestor with them.     

S型左手材料平板透镜对喇叭天线性能影响研究

根据左手材料零折射特性设计一种周期性左手材料排列的平面透镜来提高喇叭天线的增益和口径效率。S型左手材料被放置于平行波导中计算端口传输矩阵,并进一步计算S型左手材料的介电常数,调整结构参数,使其在16GHz时负介电常数为负值。将此结构所构成的周期平面透镜放置在矩形喇叭天线上端,对该天线的辐射方向图,增益进行了研究。结果表明,S型左手材料结构平面透镜的喇叭天线增益可达到19．3dB,比无透镜的同尺寸喇叭天线增益提高3．55dB。且口径效率达到64．21％。说明S型左手材料平面透镜可以大幅提高喇叭天线增益和口径效率。