Lateral interactions at inner plexiform layer of vertebrate retina: antagonistic responses to change

Lateral interactions at the inner plexiform layer of the retina of the mudpuppy were studied intracellularly after they were isolated from interactions at the outer plexiform layer with a special stimulus. The isolation was confirmed by recording no surround effect at bipolar cells under conditions that elicited a strong surround effect at ganglion cells. It appears that amacrine cell, which respond to spatiotemporal change at one retinal region, inhibit the response to change in on-off ganglion cells at adjacent sites.     

Depth perception from image defocus in a jumping spider

The principal eyes of jumping spiders have a unique retina with four tiered photoreceptor layers, on each of which light of different wavelengths is focused by a lens with appreciable chromatic aberration. We found that all photoreceptors in both the deepest and second-deepest layers contain a green-sensitive visual pigment, although green light is only focused on the deepest layer. This mismatch indicates that the second-deepest layer always receives defocused images, which contain depth information of the scene in optical theory. Behavioral experiments revealed that depth perception in the spider was affected by the wavelength of the illuminating light, which affects the amount of defocus in the images resulting from chromatic aberration. Therefore, we propose a depth perception mechanism based on how much the retinal image is defocused.     

鳜仔鱼视网膜及口腔齿的发育对摄食的适应

采用石蜡切片及HE染色的方法对鳜受精卵及1～30 d仔鱼的视网膜结构和视觉特性进行研究,结果表明:(1)受精后54 h晶状体形成,视网膜还未分化;80 h视网膜分化为外核层、内核层、内网层和神经节细胞层4层结构;98 h形成色素上皮层、视杆视锥层和神经纤维层;124 h外网层形成,视网膜10层结构发育完全。孵化后4 d开始出现少量颌齿和咽齿;5 d和14 d分别观察到腭齿和犁齿;15d时鳃耙形成但形状较小。口腔齿的数量随着仔鱼个体的生长而增加至近于成体。(2)鳜内核层分化成一层水平细胞、数层双极细胞和无长突细胞,属光感受系统不发达的类型。(3)鳜仔鱼在消化系统尚未发育完全时已经开始形成口腔齿,为提高捕食的成功率提供了基础条件,充分表现了个体发育在进化过程中与生存环境相适应的特点。(4)鳜神经节细胞层细胞随个体的生长发育而减少,孵化后29 d,体长18.36 mm时,只有一层神经节细胞,说明此时的仔鱼已适应黑暗环境生活。鳜视觉结构的变化与其从浮游到底层的生态迁移及捕食方式的变化相适应。研究亮点:从组织学研究角度对鳜仔鱼视网膜发育进行了探讨,详细研究了视网膜各组成结构的发育特征,并结合鳜仔鱼齿的发育特征,分析了其对摄食行为的适应,首次解释了伴随着视网膜发育而形成的由浮游生活到底层生活的适应,研究结果以期为鳜在种苗生产过程中正确选择开口饵料和早期动物性饵料,以降低种苗的死亡率等提供理论依据。     

Substance P activity in the bullfrog retina: localization and identification in several vertebrate species

Immunoreactive substance P is present in the bullfrog retina, possibly in two types of stratified amacrine cells, with their somas in the inner nuclear layer and their neuronal processes entering the inner plexiform layer and ramifying in sublayers 3 or 4 (or both). Occasionally, polygonal somas positive for substance P were found in the ganglion cell layer. Approximately 75 percent of the cell bodies positive for substance P and 65 percent of the radioimmunoassayable substance P were found in the superior half of the frog retina. On the basis of high-performance liquid chromatography, the immunoreactive substance P in the neural retina of the rat, monkey, or chick is similar to synthetic substance P, whereas this is not true of the immunoreactive substance P in the bullfrog or carp retina.     

鲫鱼和红腹锦鸡视网膜结构的比较组织学研究

为探讨鲫鱼(Carassius auratus)和红腹锦鸡(Chrysolophus pictus)视网膜组织结构与其生活环境的适应关系,测量了视网膜各层厚度、3个核层的胞核层数及胞核直径,并对数据进行了统计分析。结果表明:鲫鱼和红腹锦鸡视网膜均由4层细胞构成,在显微镜下分为10层。鲫鱼视网膜平均厚度为196.57μm,红腹锦鸡为225.31μm。红腹锦鸡的视网膜内核层的细胞核层数比外核层多,鲫鱼的外核层细胞核层数大于内核层。鲫鱼和红腹锦鸡这2种动物视网膜结构的差异,与其从水生到陆生的生境迁移和捕食方式的变化相适应。     

斜脉蝠蛾卵的形态及卵壳超微结构的观察

斜脉蝠蛾的卵呈卵圆形,黑色、具光泽;长0.72～0.85mm,横径最宽处为0.51～0.63 mm;卵壳明显分为两层,外层胶质状,无色透明,质地疏松,内层黑色致密,扫描电镜观察卵壳构造:①受精孔,外面观有一隆起的近似圆形的垫状构造,受精孔开口于垫状构造中间,内面观亦有一个近似扁圆锥形的隆起构造,若干个受精管分别开口于该隆起的基部和顶部,②一般卵壳区,外面观有密布颗粒状突起,并相对均匀地夹杂有柱形的围气管壁突起,内面观可见一些管、槽状构造,将卵壳内外层剥离后观察,其外层的内壁光滑无特殊构造,内层外壁除偶有刻纹状凹陷外基本光滑,透射电镜观察可见内层中有许多孔道。     

点带石斑鱼脑组织和视网膜中神经型一氧化氮合成酶的分布与定位

【目的】研究点带石斑鱼脑组织和视网膜中的一氧化氮（NO）含量及神经型一氧化氮合成酶（nNOS）分布与活性,为深入揭示NO在点带石斑鱼神经系统中的作用机制打下基础。【方法】采用NADPH-d组织化学染色法、免疫组织化学法、蛋白免疫印迹（Western blotting）及Griess试剂法,对点带石斑鱼脑组织和视网膜中nNOS的分布与活性及NO含量进行分析。【结果】经NADPH-d组织化学染色后,一氧化氮合成酶（NOS）阳性物质呈蓝色。在点带石斑鱼大脑中,NOS阳性物质位于神经元和神经纤维;在小脑中,NOS分布在颗粒层的颗粒细胞、分子层的神经纤维和浦肯野细胞层的浦肯野细胞;在视网膜中,NOS分布于色素上皮层、视锥视杆层、外核层、外网层、内核层、内网层、节细胞层和视神经纤维层。经免疫组织化学染色后,nNOS阳性物质呈深棕色。在大脑中,nNOS存在于神经元和神经纤维;在小脑中,nNOS分布在颗粒层、分子层和浦肯野细胞层;在视网膜中,nNOS分布在色素上皮层、视锥视杆层、外核层、外网层、内核层、内网层、节细胞层和视神经纤维层。Western blotting检测结果显示,点带石斑鱼脑组织和视网膜中的nNOS在显色后的硝酸纤维素膜上均出现3条免疫印迹条带,对应分子量分别为80、120和130kD。NO含量在点带石斑鱼脑组织和视网膜中分别为17.601±1.743和13.624±1.249μmol/L,nNOS活性在脑组织和视网膜中分别为38.070±3.047和23.748±2.860U/mg。【结论】在点带石斑鱼脑组织和视网膜中均存在nNOS,推测nNOS在点带石斑鱼脑神经及视神经系统生理活动中发挥重要作用。脑组织中的NO含量和nNOS活性均显著高于视网膜,是由于脑组织作为重要的中枢神经,对机体生理功能起重要调节作用。     

Unusual retinal cells in the dolphin eye

By comparison to the cellular constituents of the retinas of certain other diving mammals, the elements of the dolphin retina include an unusually large number of specialized cells. Both cone and rod receptors may be identified. An unusual amacrine cell may be seen which produces a process that spans the cells between the inner plexiform and outer plexiform layers. Most unusual is a layer of giant ganglion cells which appears to serve most of the central retina. The giant ganglion cells support giant dendrites and optic nerve fibers which range up to 8 micrometers in diameter.     

Synaptic connections of the centrifugal fibers in the pigeon retina

The centrifugal fibers in the pigeon retina end in the inner nuclear layer and form two kinds of terminals, convergent and divergent. In the inner nuclear layer the fibers synapse with amnacrine and displaced ganglion cells. Because of their great number and their even distribution these fibers appear to constitute a system for the localized centrifugal control of the retinal functions.     

Acetylcholinesterase: method for demonstration in amacrine cells of rabbit retina

The activity of acetylcholinesterase in the inner plexiform layer of the rabbit retina was not affected detectably by prior section of the optic nerve. After the animals were treated with diisopropyl phosphorofluoridate, acetylcholinesterase reappeared in the somata of the amacrine cells and in certain cells of the ganglion cell layer before it reappeared in the inner plexiform fibers. This confirms the normal presence of acetylcholinesterase at the former site. The possible role of acetylcholine in intraretinal transmission is considered.     

棕色田鼠视网膜结构及其神经元特异性烯醇化酶分布研究

通过H-E.染色法和免疫组化方法,对棕色田鼠视网膜结构及神经元特异性烯醇化酶的分布特性进行研究.结果表明,棕色田鼠的视网膜结构呈典型的脊椎动物视网膜结构类型,由外向内分别为色素上皮、视锥视杆层、外核层、外网层、内核层、内网层、节细胞层、神经纤维层.视网膜中神经元特异性烯醇化酶阳性分布在内网层、内核层、靠近内核层的外网层区、节细胞层、神经纤维层,其中内网层阳性最强,有4个阳性亚层.视锥视杆层和外核层没有神经元特异性烯醇化酶分布,这可能与感光细胞的分泌有关.     

Morphological identification of serotonin-accumulating neurons in the living retina

Neurons that accumulate the transmitter serotonin have been identified in the living retina by being labeled with 5,7-dihydroxytryptamine (5,7-HT), an autofluorescent serotonin analog. Iontophoretic injection of Lucifer yellow into the labeled cells under microscopic control revealed that the serotonin-accumulating neurons in rabbit retina constitute two morphological types of amacrine cells, termed S1 and S2, whose distal dendrites are stratified at the inner margin of the inner plexiform layer. The dendritic overlap of the S1 type is extraordinarily large: each point on the retina is covered by the fields of 550 to 900 S1 amacrines, and 6 to 8 meters of their dendrites are packed into each square millimeter of retina. Such a pervasive neuropil may provide an effective substrate for diffuse transmitter release, as proposed for serotonergic fibers elsewhere in the central nervous system.     

具有温度约束的设备双层保温经济厚度计算

对于设备保温而言，两层保温材料夹缝处的温度即为外层保温的最大可能使用温度，而该蔡同时受到内，外层保温材料厚度变化的影响。为得到双层保温材料的经济厚度，就要合理调整内，外层保温材料厚度，根据传热学原理，建立了具有温度约束时的双层保温最优化目标函数和约束条件，采和内部惩罚函数法对约束最优化问题进行了求解。     

无孔小咽属线虫2个新记录种的报道

2008年在采集到的胶南市蓝莓(Vaccinium corymbosum L.)根际土中,分离鉴定出无孔小咽属2个中国新记录种,分别为非同无孔小咽线虫Aporcelaimellus alius和食淀粉无孔小咽线虫A.amylovorus。其中,非同无孔小咽线虫A.alius的鉴定特征是雌虫虫体强壮,唇区缢缩明显,角质层由明显的两层组成,阴唇骨化明显,尾长是肛门处体宽的0.7～0.8倍;食淀粉无孔小咽线虫A.amylovorus的鉴定特征是虫体中等,唇区缢缩明显,角质层光滑,由两层构成,雌虫阴唇骨化明显,尾长是肛门处体宽的0.9～1.1倍。     

藤类幼苗叶维管束鞘的超微结构研究

在研究的３种藤类的小叶脉里，其维管束鞘大多数都有一层拟内皮层外鞘细胞，其内方则多有１至几层厚壁的内鞘细胞。本文在超微结构水平上描述了内，外鞘细胞。最后，讨论了棕榈科及禾本科的一些解剖文献中的有关问题。     

PCR-DGGE技术分析蛋鸡MHC基因对肠道细菌种群结构的影响

 【目的】研究蛋鸡MHC（Major Histocompatibility Complex,主要组织相容性复合物）基因对不同周龄和不同部位肠道细菌种群结构的影响。【方法】使用基于16S rDNA的PCR-DGGE技术,结合特异性和共性条带割胶回收DNA进行克隆和测序,对2,4,6和8周龄商品蛋鸡和15I5系蛋鸡嗉囊、十二指肠、空肠、回肠和盲肠内含物细菌群落的结构和多样性进行比较,鉴定8周龄蛋鸡部分特异性和共性群落成员。【结果】商品蛋鸡和15I5系蛋鸡盲肠细菌的多样性最高,其次是回肠和空肠,嗉囊和十二指肠的细菌多样性比较低,且随着蛋鸡周龄增加,各肠段细菌多样性呈上升趋势,MHC基因对细菌多样性无显著影响。DGGE图谱聚类分析表明,蛋鸡MHC基因对4、6周龄肠道细菌的影响最大,对2周龄影响最小;而且MHC基因对消化道前段细菌的影响小于对后段影响。序列分析发现,8周龄商品蛋鸡和15I5系蛋鸡均有大量的三得利乳杆菌（Lactobacillus suntoryeus）,是蛋鸡消化道前段的优势细菌;商品蛋鸡空肠、回肠和盲肠中的特异性条带主要是Ochrobactrum spp,索氏梭菌（Clostridium sordellii）,超巨巨单胞菌（Megamonas hypermegale）和大量不可培养的细菌;15I5系蛋鸡的特异性条带主要是不可培养的细菌。【结论】蛋鸡MHC基因可影响不同周龄、不同肠段细菌群落的结构。     

细毛羊腹毛高弯问题的研究(Ⅰ)——东北细毛羊皮肤组织结构特点的研究

本研究采用了有腹毛高弯的和无高弯的东北细毛羊71只,其中有9—12月龄的小母羊和二年以上的成年母羊。样本取自肩后部和脐部。研究自1981年10月末至1982年2月末进行。用常规组织学方法,对皮肤各层、毛囊、毛根和汗腺进行了观察。1.测量了表皮、乳头层、中间层及网状层的厚度;毛、毛囊群、皮脂腺及汗腺的直径;皮脂腺及汗腺在每一平方毫米内的数量。2.成年母羊脐部皮肤的乳头层及网状层比肩部为厚,皮脂腺发达,毛裳数较少。3.小母羊与成年母羊相比,肩后部的乳头层较薄;脐部毛深较短;肩后部每一平方毫米皮脂腺数和毛数较多;出现残留髓质粗毛的个体数较多。4.皮肤结构的季节变化显著。5.明确了羊真皮分为乳头层、中间层及网状层的根据。6.明确了羊毛囊及毛根各段特点。7.有高弯腹毛和无高弯腹毛羊的毛囊弯曲情况及皮肤其它各结构未发现显著差异。     

Spatial variability of soil properties in red soil and its implications for site-specific fertilizer management

Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas. To explore the relationship between soil spatial variability and land management, 256 samples were randomly collected at two depths(surface layer 0–20 cm and subsurface layer 20–40 cm) under different land use types and soil parent materials in Yujiang County, Jiangxi Province, a red soil region of China. The pH, soil organic matter(SOM), total nitrogen(TN), cation exchange capacity(CEC), and base saturation(BS) of the soil samples were examined and mapped. The results indicated that soils in Yujiang were acidified, with an average pH of 4.87(4.03–6.46) in the surface layer and 4.99(4.03–6.24) in the subsurface layer. SOM and TN were significantly higher in the surface layer(27.6 and 1.50 g kg~(–1), respectively) than in the subsurface layer(12.1 and 0.70 g kg~(–1), respectively), while both CEC and BS were low(9.0 and 8.0 cmol kg~(–1), 29 and 38% for surface and subsurface layers, respectively). Paddy soil had higher pH(mean 4.99) than upland and forest soils, while soil derived from river alluvial deposits(RAD) had higher pH(mean 5.05) than the other three parent materials in both layers. Geostatistical analysis revealed that the best fit models were exponential for pH and TN, and spherical for BS in both layers, while spherical and Gaussian were the best fitted for SOM and CEC in the surface and subsurface layers. Spatial dependency varied from weak to strong for the different soil properties in both soil layers. The maps produced by selecting the best predictive variables showed that SOM, TN, and CEC had moderate levels in most parts of the study area. This study highlights the importance of site-specific agricultural management and suggests guidelines for appropriate land management decisions.     

Local retinal regions control local eye growth and myopia

In chicks, visual deprivation leads to myopia and enlargement of the vitreous chamber of the eye. When chicks were raised with white translucent occluders over their eyes so that either the nasal half, the temporal half, or all of the retina was visually deprived, the resulting myopia (median = -15 diopters) was limited to the deprived part of the retina, regardless of which half of the retina was visually deprived; the nondeprived part remained nearly emmetropic. Correspondingly, the vitreous chamber was elongated only in the region of the visual deprivation, resulting in eyes with different asymmetric shapes depending on which retinal region was deprived. These results argue for a local regulation of ocular growth that is dependent on vision and suggest a hypothesis to explain the epidemiological association of myopia in humans with large amounts of reading. Because most nonfoveal retinal neurons have large receptive fields, they cannot resolve the individual letters on the printed page; this may lead to their activity being less during reading than during most other forms of visual stimulation. Thus, the impoverished stimulus situation of reading may lead to myopia, as do other types of visual form deprivation.     

Spatial buffering of light-evoked potassium increases by retinal Müller (glial) cells

Activity-dependent variations in extracellular potassium concentration in the central nervous system may be regulated, in part, by potassium spatial buffering currents in glial cells. The role of spatial buffering in the retina was assessed by measuring light-evoked potassium changes in amphibian eyecups. The amplitude of potassium increases in the vitreous humor was reduced to approximately 10 percent by 50 micromolar barium, while potassium increases in the inner plexiform layer were largely unchanged. The decrease in the vitreal potassium response was accurately simulated with a numerical model of potassium current flow through Müller cells, the principal glial cells of the retina. Barium also substantially increased the input resistance of Müller cells and blocked the Müller cell-generated M-wave, indicating that barium blocks the potassium channels of Müller cells. Thus, after a light-evoked potassium increase within the retina, there is a substantial transfer of potassium from the retina to the vitreous humor by potassium current flow through Müller cells.