The edge cell, a possible intraspinal mechanoreceptor

In the lateral edge of the "white matter" in the lamprey spinal cord, there is a group of nerve cells referred to as edge cells. The results of a combined physiological, light microscopical, and electron microscopical study suggest that these cells serve as intraspinal mechanoreceptors. Edge cells are depolarized on stretch of the lateral margin of the spinal cord, and they have nestlike ramifications in this region oriented in a rostrocaudal plane. These cells exhibit a close structural similarity with the crayfish stretch receptor.     

Physiological limits for "subliminal" perception

Cortical, subcortical, and peripheral sensory nerve potentials were studied in cats to determine comparative thresholds of response. Stimuli capable of eliciting responses in peripheral nerve also invariably elicited responses from thalamus and cortex. Together with relevant data from human studies, the results indicate that stimuli subthreshold for perception do not affect the nervous system. They also have implications for studies of "subliminal" perception.     

家猪染色体Q-和G-及C-分带的多态性

对杜洛克、巴克夏、关中黑和八眉猪的Q-、G-和C-分带的多态性作了祥细的比较分析。发现Q-,G-分带在品种、个体及同源染色体间有多态性。随着染色体的伸长和带纹的进一步精细,多态性表现的愈多愈明显;C-分带的多态性在品种、个体、细胞及同源染色体间广泛存在,同源染色体间C-带多态性具品种特征和个体特征。此外,发现家猪染色体中存在“额外”G-带和“额外”浅染区现象。     

特异观赏桃品种"菊花桃"和"红叶桃"幼树光合特性研究

试验以栽培品种朝晖为对照,对比研究了观赏桃品种菊花桃、红叶桃的光合特性。结果表明,菊花桃、红叶桃9:00、10:00时光合速率低于对照品种朝晖,但红叶桃对弱光的利用能力和菊花桃对低浓度CO2的利用能力较强。试验同时对这些品种的光合特性指标和干物质积累进行相关性分析发现,羧化效率、气孔导度和蒸腾速率与营养生长显著相关。因此在菊花桃、红叶桃用于绿化栽培前,在可控CO2的设施中培育壮苗,同时注意通过控温和控湿调节气孔的运动来调节水分蒸腾,是2个观赏桃栽培的关键步骤。     

Interocular Transfer of Brightness Discrimination in "Split-Brain" Cats

"Split-brain" cats with midsagittal section of the optic chiasm and the corpus callosum are able to transfer interocularly a simple brightness discrimination although they are unable to transfer a pattern discrimination. This strongly suggests that the interocular transfer of a simple brightness discrimination is mediated subcallosally.     

Significance of "tethyan" fossils in the american cordillera

Equatorial faunas of the ancient Tethyan seaway, which extended from western Europe to southeastern Asia, comprise some of the most diverse marine taxa in the fossil record. Comparable or identical "Tethyan" species that occur far from the Tethyan seaway in Paleozoic and Mesozoic rocks of the North and South American Cordillera have long been considered as a major biogeographic anomaly. Two leading theories to account for the occurrence of these anomalous "Tethyan" faunas in the Cordillera are that they were transported long distances to the east on tectonic blocks(suspect terranes that originated near the Tethys) or that they migrated westward via undiscovered marine corridors through continental areas of Pangea. An alternative model is that these "Tethyan" fauna were pantropic species that extended with attenuated diversities into the eastern proto-Pacific Ocean. This pantropic model can better account for the distribution patterns of many Paleozoic and early Mesozoic "Tethyan" species in the American Cordillera and provides a steady state hypothesis against which the other models can be tested. The distribution of pre-Cretaceous "Tethyan" faunas is similar to the known pantropic distribution of many Cretaceous and Cenozoic tropical biotas. During the Cenozoic, taxa were most diverse in the Tethys and Indo-West Pacific regions but extended with attenuated diversity to many parts of the equatorial Pacific Ocean, including the west coasts of North and South America. The eastern Pacific occurrence of many Indo-West Pacific species provides a modern analog for the occurrence of many anomalous "Tethyan" fossils in the American Cordillera.     

The anion paradox in sodium taste reception: resolution by voltage-clamp studies

Sodium salts are potent taste stimuli, but their effectiveness is markedly dependent on the anion, with chloride yielding the greatest response. The cellular mechanisms that mediate this phenomenon are not known. This "anion paradox" has been resolved by considering the field potential that is generated by restricted electrodiffusion of the anion through paracellular shunts between taste-bud cells. Neural responses to sodium chloride, sodium acetate, and sodium gluconate were studied while the field potential was voltage-clamped. Clamping at electronegative values eliminated the anion effect, whereas clamping at electropositive potentials exaggerated it. Thus, field potentials across the lingual epithelium modulate taste reception, indicating that the functional unit of taste reception includes the taste cell and its paracellular microenvironment.     

Stretch-inactivated ion channels coexist with stretch-activated ion channels

Stretch-activated ion channels of animal, plant, bacterial, and fungal cells are implicated in mechanotransduction and osmoregulation. A new class of channel has now been described that is stretch-inactivated. These channels occur in neurons, where they coexist with stretch-activated channels. Both channels are potassium selective. The differing stretch sensitivities of the two channels minimize potassium conductance over an intermediate range of tension, with the consequence that, over this same range, voltage-gated calcium channels are most readily opened. Thus, by setting the relation between membrane tension and transmembrane calcium fluxes, stretch-sensitive potassium channels may participate in the control of calcium-dependent motility in differentiating, regenerating, or migrating neurons.     

Voltage-dependent calcium channels in glial cells

The electrophysiological properties of glial cells were examined in primary culture in the presence of tetraethylammonium and Ba2+, a treatment that reduces K+ permeability of the membrane and enhances currents through voltage-dependent Ca2+ channels. Under these conditions, glial cells showed both spontaneous action potentials and action potentials evoked by the injections of current. These responses appear to represent entry of Ba2+ through Ca2+ channels because they were resistant to tetrodotoxin but were blocked by Mn2+ or Cd2+.     

Energy gaps in "metallic" single-walled carbon nanotubes

Metallic single-walled carbon nanotubes have been proposed to be good one-dimensional conductors. However, the finite curvature of the graphene sheet that forms the nanotubes and the broken symmetry due to the local environment may modify their electronic properties. We used low-temperature atomically resolved scanning tunneling microscopy to investigate zigzag and armchair nanotubes, both thought to be metallic. "Metallic" zigzag nanotubes were found to have energy gaps with magnitudes that depend inversely on the square of the tube radius, whereas isolated armchair tubes do not have energy gaps. Additionally, armchair nanotubes packed in bundles have pseudogaps, which exhibit an inverse dependence on tube radius. These observed energy gaps suggest that most "metallic" single-walled nanotubes are not true metals, and they have implications for our understanding of the electronic properties and potential applications of carbon nanotubes.     

普通高校实施“阳光体育运动”对策研究

“阳光体育运动”是新时期加强青少年体育意识,增强青少年体质的战略举措。普通高校开展与实施“阳光体育运动”要提高认识,认真贯彻《学生体质健康标准》,深化体育教学改革,提高体育课教学质量。阳光体育运动的开展与实施是高校体育改革与发展的必然,对于促进高校体育教学具有有效性和可行性。     

A virus-encoded "superantigen" in a retrovirus-induced immunodeficiency syndrome of mice.

The development of an immunodeficiency syndrome of mice caused by a replication-defective murine leukemia virus (MuLV) is paradoxically associated with a rapid activation and proliferation of CD4+ T cells that are dependent on the presence of B cells. The responses of normal spleen cells to B cell lines that express the defective virus indicated that these lines express a cell surface determinant that shares "superantigenic" properties with some microbial antigens and Mls-like self antigens. This antigen elicited a potent proliferative response that was dependent on the presence of CD4+ T cells and was associated with selective expansion of cells bearing V beta 5. This response was markedly inhibited by a monoclonal antibody specific for the MuLV gag-encoded p30 antigen.     

小鼠早期胚胎细胞膜电位的测定及胚胎早期分化诱因的探讨

目的:调查早期胚胎细胞分化的诱因。方法:使用Patch clamp7型膜电位测定仪,测定ICR小鼠4、8、16、32细胞期胚胎的细胞膜电位。结果:①细胞位置无差异时,胚胎细胞的膜电位差异不显著;②早期胚胎的细胞膜电位存在个体差异;③早期胚胎的细胞在不同发育阶段具有不同的膜电位,且其膜电位值显著下降;④同—胚胎的周边细胞与内部细胞之间,细胞膜电位存在显著性差异。结论:早期胚胎分化的诱因是不同位置的细胞受到"胚胎场"的影响不同,"胚胎场"是指构成胚胎的细胞,因其具有的膜电位因素在相互之间形成的影响力。     

Olfactory bulb response of rabbit

An approach to understanding the properties of dendrites is to record the response of the olfactory bulb where the dendrites of mitral cells form the glomeruli. After the stimulations of the bulb and nasal mucosa, the responses appear different, but they are fundamentally composed of three successive potentials, suggesting that the last one is the action potential of glomerular dendrites.     

"Intrinsic" immunological tolerance in allophenic mice

Mice experimentally derived from pairs of conjoined, undifferentiated, cleavage-stage embryos of different histocompatibility genotypes can retain cells of each strain, which still produce their characteristic antigenic products. The animals are permanently tolerant of cells of both original types, remain free of runt disease, and display a normal and specific immune response to introduction of a foreign antigen. Absence of autoimmunity in development of ordinary animals is explainable by the "intrinsic" kind of tolerance found here.     

SQL Server数据库"置疑"的原因及解决方法

SQL Server数据库因为软件,硬件或人为因素,常常被标记为"置疑",而导致数据库不能正常访问.文中给出了SQL Server数据库"置疑"的几种原因,以及由这些原因引起而采用相应的解决方法.这些解决方法均通过实践证明,简便可行,安全可靠,能够达到恢复数据库的目的.     

优化水稻性状组配中“三好理论”的验证及评价

水稻超高产育种是当今世界的热门,也是难题．沈阳农业大学稻作研究室积多年以来的实际经验,早就致力于此,并已在１９８７年国内外刊物上有所讨论,首先提出理想株形与优势利用相结合的大方向．嗣后汲取各家之长,采用“偏矮秆”与“偏大穗”的材料试验不理想,又由“两偏”转向“三好”（植株高矮好,稻穗大小好和分蘖力强弱好）．经１９９１～１９９３年的验证,特别是１９９３年辽中县示范”三好一号”的验证,认为在理论上由“两好”转向“三好”是杂交后代选择标准的进一步完善,具有学科开拓性;在实践上,３年便有小成,改变了步履艰难的局面,也有要而不烦的实用性．本研究并且可能是自发地运用现代的控制理论于水稻育种的首例．     

谈新国家标准《机械制图》中一些概念的科学性

国家标准机械制图中的概念应体现其科学性,即能反映客观实际和反映其不质属性。本文就新国标中的几个概念,阐明只有建立在科学基础上的术语、概念才能被各方面所接受,才有统一的实践基础。     

中国传统佛教与日本“批判佛教”

从20世纪初开始,一直有日本学者质疑中国传统佛教并非真佛教,最后酝酿出"批判佛教"的思潮。他们在误会《阿含经》缘起法的前提下,强力否定以如来藏之修证为中心的中国传统佛教。影响所及,台湾佛学研究出现了日本化的倾向。事实上,如来藏并不违背《阿含经》。《阿含经》的"我"和"识界"等名相,以及入胎识、持身识等观念,说的都是如来藏,也是实质上的大乘法。