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.     

Structure of PTB bound to RNA: specific binding and implications for splicing regulation

The polypyrimidine tract binding protein (PTB) is a 58-kilodalton RNA binding protein involved in multiple aspects of messenger RNA metabolism, including the repression of alternative exons. We have determined the solution structures of the four RNA binding domains (RBDs) of PTB, each bound to a CUCUCU oligonucleotide. Each RBD binds RNA with a different binding specificity. RBD3 and RBD4 interact, resulting in an antiparallel orientation of their bound RNAs. Thus, PTB will induce RNA looping when bound to two separated pyrimidine tracts within the same RNA. This leads to structural models for how PTB functions as an alternative-splicing repressor.     

气候变迁对农业的冲击与调适

工业革命以来,随着大量能源和自然资源的消耗,导致大气中温室气体增加,全球暖化,海平面上升;气候变迁对人类生存环境产生了巨大的影响和冲击。本文从气候变迁与农业生产关系入手,分析了气候变迁对农业正负两面的效应,并着重分析气候变迁对农业生产面和农村经济社会的负面影响,最后从生态保育与绿色农业的发展思路出发,提出调整农业资源利用和生产方式,以应对气候变迁对农业的冲击。     

达氟沙星对施氏鲟非特异性免疫功能的影响

采用经口灌服的方法,分别用20、50和100 mg.kg-1达氟沙星对施氏鲟连续给药20 d(每天1次),并于给药后第5、10、15和20天测定非特异性免疫指标.结果表明:达氟沙星对肝脏和血清溶菌酶含量有抑制作用;20和50 mg.kg-1组对血清中酚氧化酶活力先诱导后抑制,100 mg.kg-1组则始终表现抑制作用;该药使白细胞数量和细胞吞噬百分比降低,但对白细胞吞噬指数及肝脏和脾脏系数无显著影响(P>0.05).可见,达氟沙星使施氏鲟的非特异性免疫能力降低,但对免疫器官的生长指数没有明显的影响.     

壳聚糖对草鱼非特异性免疫功能的影响

选择平均体重(70.61±1.29)g的健康草鱼450尾,随机分成5个处理组,即基础饲料组、抗生素组、0.25%、0.50%及1.00%壳聚糖组,每个处理设3个重复,每个重复放养30尾鱼,进行为期40d的饲养试验.结果表明,日粮中添加壳聚糖能显著增加草鱼的后肾体指数(P0.05),对草鱼的头肾体指数和脾体指数影响不显著,但与基础饲料组相比,各壳聚糖添加组草鱼的头肾体指数和脾体指数有增加趋势(P0.05).添加0.50%壳聚糖能显著增加草鱼血清总蛋白含量(P0.05),对草鱼血清和肝胰脏总SOD活力影响不显著(P0.05),但有增加趋势.即草鱼日粮中添加适量的壳聚糖能提高机体非特异性免疫能力,其适宜添加剂量为0.50%.     

Interocular effects in prism adaptation

Monocular prism after-effects were measured in three groups of subjects each of whom had walked about wearing a 20-diopter prism, base up, over the right eye and one of the following over the left eye: a diffusing screen, 0-diopter prism, or a 20-diopter prism, base down. The performance of the third group showed that visual-motor spatial coordination in the adult is subject to at least limited interocular independence.     

Light adaptation in cat retinal rods

It has long been an open question whether individual rod receptors in the mammalian retina show any light adaptation. The prevailing evidence so far has suggested that these cells, unlike those in lower vertebrates, adapt little if at all. The experiments on cat rods reported here, however, indicate that this is not really true. Since the cone system in the cat retina has a fairly high light threshold, the rods also need to adapt so that they do not saturate with light before the cones fully take over vision at higher light intensities. In similar experiments, adaptation was found in rods of other mammalian species, including primates.     

Cellular adaptation to morphine in rats

The respiration of KCl-stimulated cortical slices of brain from control rats is markedly depressed by morphine, whereas the respiration of those from rats chronically dosed with morphine is unaffected. The results demonstrate an adaptation to morphine at the cellular level which is concomitant with the adaptation of the whole animal to morphine     

鹦鹉血清非特异性凝集因子消除试验研究

我国检验检疫部门在工作中发现鹦鹉血清中存在非特异性凝集因子,严重影响血凝抑制试验中红细胞被抑制凝集,从而造成试验结果的误判。为解决这一问题,本试验采用将待检鹦鹉血清用20%鸡红细胞生理盐水悬液处理15min,可消除全部30份被检血清中的非特异性凝集现象。对除去非特异性凝集因子的血清与未处理血清所做的HI试验的准确率进行比较,差异极显著(t检验P<0.01)。表明本研究采用的方法可有效保证鹦鹉血清HI试验的准确性。     

Global flexibility in a sensory receptor: a site-directed cross-linking approach

The aspartate receptor of Escherichia coli and Salmonella typhimurium is a cell surface sensory transducer that binds extracellular aspartate and sends a transmembrane signal to the inside of the bacterium. The flexibility and allostery of this receptor was examined by placing sulfhydryl groups as potential cross-linking sites at targeted locations in the protein. Seven different mutant receptors were constructed, each containing a single cysteine residue at a different position in the primary structure. Intramolecular disulfide bond formation within oligomers of these mutant receptors is shown to trap structural fluctuations and to detect ligand-induced changes in structure. The results indicate that the receptor oligomer has a flexible, dynamic structure which undergoes a global change upon aspartate binding.     

合金钢网柔性块体在堤坝除险加固中的应用

从堤坝基础防护材料的比较分析出发,介绍了合金钢网柔性块体的防护机理、性能及技术优势,并用实例说明了柔性块体在水利上的应用。     

小麦皖89236丰产性及适应性分析

本文根据我省及黄淮区试、生产试验资料，分析了皖８９２３６小麦的增产潜力、产量三要素通径系数和动态结构，并作了抗逆抗病性模糊评判等，结果表明皖８９２３６产量分布主要集中在５２５０—７５００ｋｇ／ｈａ；随产量水平上升，三要素的总趋势是上升的，但穗粒数在产量水平低于６７５０ｋｇ／ｈａ时上升较快，而成穗数、千粒重则在产量水平高于６７５０ｋｇ／ｈａ时增幅较大；对产量的贡献，成穗数＞穗粒数＞千粒重。三要素间相关系数较大，因而自调能力强，综合抗性好，对白粉、叶锈、叶枯、赤霉等病害中－高抗，抗倒伏，耐青干，稳产性好，适应范围广，是个潜力很大的材料。     

Spatial learning as an adaptation in hummingbirds

An ecological approach based on food distribution suggests that humming birds should more easily learn to visit a flower in a new location than to learn to return to a flower in a position just visited, for a food reward. Experimental results support this hypothesis as well as the general view that differences in learning within and among species represent adaptations.     

Crystal structure analysis of deamino-oxytocin: conformational flexibility and receptor binding

Two crystal structures of deamino-oxytocin have been determined at better than 1.1A resolution from isomorphous replacement and anomalous scattering x-ray measurements. In each of two crystal forms there are two closely related conformers with disulfide bridges of different chirality, which may be important in receptor recognition and activation.     

Monocular and binocular aftereffects of chromatic adaptation

Supersaturated greens seen after long-wavelength adaptation depend upon contrast from the continuing afterdischarge of bleached "red" receptors in the surround, rather than merely upon inactivation from bleaching of "red" receptors in the test spot area. When test spot and bleach field coincide spatially, supersaturated greens are not seen. Since color mixing but not contrast was found binocularly, color contrast must be a retinal phenomenon.