Bioelectric activity in long-term cultures of spinal cord tissues

Fragments of embryonic spinal cord (human, rat, and chick) can regenerate and differentiate in tissue culture. Complex bioelectric activity evoked by electric stimuli indicates that nerve cells in cultures may maintain, for months in vitro, not only the capacity to propagate impulses along their neurites but also a remarkable degree of functional organization resembling the activity of synaptic networks of the central nervous system.     

Bioelectric phenomena related to protein-fixed charge in a crab nerve fiber

The bioelectrical characteristics of a crab nerve fiber subjected to solutions containing the impermeant anions ferrocyanide, glutamate, or ethanolsulfate substituted for chloride include prolonged slow depolarizations that elicit prolonged trains of impulses sulperimposed on the plateau portion. Propionate and nitrate depress repetitive firing while thiocyancite has only a slighit effect. Nerves treated with ferrocyanide lose potassium and gain sodium, which fact may account for their depolarization. On the other hand, studies with interference microscopy reveal shift by ferrocyanide in the interference fringe pattern of the sheath material; this suggests a reorientation of fixed charges in the protein layers by direct action of the anion on these layers. This may also account for the electrical manifestations observed.     

农村低压电网触电生物电流频谱特性分析

针对农村低压电网发生触电故障时触电生物电流及其成分分量的复杂性和多样性,采用快速傅里叶变换对触电生物实验获取的电源电压、剩余电流以及触电生物电流进行频谱分析,明确了剩余电流与触电生物电流频谱特性及各成分分量变换过程。仿真实验表明:在触电故障发生时剩余电流与触电生物电流相关系数为0.999,其中触电生物电流中直流分量的最大畸变率最大可达0.044 5,2~5次谐波的最大畸变率分别为0.013 4,0.035 4,0.006 9,0.014 2,能够为提取生物触电故障过程中剩余电流的变化规律提供依据。     

Oyster ciliary inhibition by cystic fibrosis factor

Ciliary inhibition in oysters serves as an assay in identifying a serum factor in cystic fibrosis patients and heterozygotes. Seriums from 47 patients With cystic fibrosis antd 19 heterozygotes caused ciliary cessation within 35 minutes, whereas serums from only 2 of 64 individuals without cystic fibrosis inhibited ciliary activity within this time.     

Aluminum in seawater: control by biological activity

The distribution and concentration of dissolved aluminum in a vertical hydrographic profile in the Mediterranean Sea near Corsica are controlled by biological activity. The concentrations of dissolved silica and aluminum covary in the profile and exhibit minima coincident with the seasonal thermocline, a nitrate minimum, and an oxygen maximum. These observations support the hypothesis that the silicon and aluminum cycles in the oceans are linked through the activity of diatoms.     

Alcohol dehydrogenase in maize: genetic control of enzyme activity

A gene (Adhr(r)) which controls the activity of alcohol dehydrogenase in the scutellum of maize has been found. This gene is not allelic to the Adh(1) locus, which specifies the charge of the enzyme molecule and hence its migration rate. The two genes are linked and located about 17 crossover units apart. The Adh(r)(N) allele specifies equal activities of both the Adh(1)(S) and Adh(1)(F) products. The Adh(r)(L) allele gives lower activities of the Adh(1)(S) products only and operates in both the cis and the trans configurations.     

Cholinergic interneurons control local circuit activity and cocaine conditioning

Cholinergic neurons are widespread, and pharmacological modulation of acetylcholine receptors affects numerous brain processes, but such modulation entails side effects due to limitations in specificity for receptor type and target cell. As a result, causal roles of cholinergic neurons in circuits have been unclear. We integrated optogenetics, freely moving mammalian behavior, in vivo electrophysiology, and slice physiology to probe the cholinergic interneurons of the nucleus accumbens by direct excitation or inhibition. Despite representing less than 1% of local neurons, these cholinergic cells have dominant control roles, exerting powerful modulation of circuit activity. Furthermore, these neurons could be activated by cocaine, and silencing this drug-induced activity during cocaine exposure (despite the fact that the manipulation of the cholinergic interneurons was not aversive by itself) blocked cocaine conditioning in freely moving mammals.     

虫溃啶对水稻三化螟的生物活性和田间防治研究

经室内生测和田间试验结果表明，虫溃啶对三化螟具有较高的毒力，其LC50为3.35mg/L，均高于对照药剂三唑磷和杀虫单，对二代，三代三代螟具有较好的控制效果；生产应用时，防治二代三化螟适宜用量为60-80ml/667m^2，三代三化螟为80-100ml/667m^2，防治适期在卵孵高峰前。     

Adrenergic innervation of the parasympathetic ciliary ganglion in the chick

The chick ciliary ganglion receives a nonvascular symathetic innervation in addition to the well-known cholinergic one; fluorescent, varicose adrenergic fibers form pericelluar baskets. Adrenergic fibes were identified electron microscopically in ganglia fixed with potassium permanganate. The fibers degenerate after injection of 6-hydroxydopamine. No true synaptic relationships involving adrenergic varicosities and ganglion cells or cholinergic terminals were demonstrable. The distribution of the adrenergic fibers suggests a kind of "distance à synapse" with the choroidal cells or with the preganglionic fibers (or both). The adrenergic innervation might provide a modulation of the cholinergic transmission.     

Eyes have a role in photoperiodic control of sexual activity of coturnix

In blinded Japanese quail (Coturnix coturnix japonica) encephalic photoreception of the stimulus from long photoperiods is sufficient to induce and maintain normal gonadal function in females (egg laying) and in males (enlargement of the cloacal gland). However, the termination of sexual activity by short days is dependent on these birds having experienced long days at the time of blinding.     

Critical point drying for scanning electron microscopic sthdy of ciliary motion

Scanning electron microscopic study of tile pattern of ciliary coordination and the form of the ciliary beat is now possible. Rapid fixation stops tile ciliary activity instantaneously, and critical point drying avoids distortion of the cilia by surface tension forces. Such stuidies have been made on the ciliate Opalina with this new technique.     

Morphine-induced delay of normal cell death in the avian ciliary ganglion

Repeated administration of morphine in increasing doses delayed normal cell death in the ciliary ganglion of the chick embryo; the effect was completely blocked by naloxone. Survival of spinal motoneurons was not affected. Morphine also inhibited potassium-stimulated synthesis of acetylcholine in ganglion cells cultured with muscle, suggesting that morphine can influence neurotransmission. Morphine's effect on cell death may be due to an inhibition of transmission at the neuromuscular junction, but opiates may also directly affect cell death. Although it is now known whether the endogenous opiates in the ciliary ganglion influence neuronal survival during embryogenesis, exogenous opiates can affect normal cell death in the autonomic nervous system.     

Control of embryonic motoneuron survival in vivo by ciliary neurotrophic factor

During development of the nervous system, neurons in many regions are overproduced by proliferation, after which the excess cells are eliminated by cell death. The survival of only a proportion of neurons during normal development is thought to be regulated by the limited availability of neurotrophic agents. One such putative trophic agent is ciliary neurotrophic factor (CNTF), a polypeptide that promotes the survival of ciliary, sensory, and sympathetic neurons in vitro. In contrast to the results of in vitro studies, however, the daily treatment of chick embryos in vivo with purified human recombinant CNTF failed to rescue any of these cell populations from cell death, whereas CNTF did promote the in vivo survival of spinal motoneurons. Thus, CNTF may not act as a neurotrophic agent in vivo for those embryonic neurons (especially ciliary neurons) on which it acts in vitro. Rather, CNTF may be required for in vivo survival of motoneurons.     

过氧乙酸对池塘水体的增氧抑菌抑藻效果研究

为寻找一种既安全可靠,又能增加水体溶氧、杀灭水体病原菌并改善水体环境的抑藻试剂,用多功能水质分析仪检测在10、20、30℃条件下,过氧乙酸(体积分数为15%)在池塘水和蒸馏水中的放氧效果。结果表明:温度越高放氧越快,但温度越高氧气的饱和量越低,气体外溢,故测出的溶解氧浓度数值较低;采用滤纸片法和二倍稀释法测定过氧乙酸和3种常用杀菌剂对6种常见水产病原菌(副溶血弧菌、维氏气单胞菌、嗜水气单胞菌、溶藻弧菌、沃氏葡萄球菌和腐生葡萄球菌)的抑菌效果,结果显示,抑菌效果依次为恩诺沙星>过氧乙酸>聚维酮碘>高锰酸钾;对暂养的黄丝藻藻华进行毒杀,结果显示,随着时间的延长,加入高浓度过氧乙酸的试验组水体开始混浊,藻丝体开始断裂,叶绿素a含量减少;各时段下,过氧乙酸浓度组叶绿素a含量明显低于对照组(P<0.05),随着时间的延长各浓度组超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量均呈先增长后下降的趋势,说明黄丝藻藻丝体受到了过氧乙酸的破坏,开始解体甚至死亡。研究表明,在水产养殖池塘中使用过氧乙酸,增氧、抑菌、抑藻效果明显。     

过氧乙酸对池塘水体的增氧抑菌抑藻效果研究

为寻找一种既安全可靠,又能增加水体溶氧、杀灭水体病原菌并改善水体环境的抑藻试剂,用多功能水质分析仪检测在10、20、30℃条件下,过氧乙酸(体积分数为15%)在池塘水和蒸馏水中的放氧效果。结果表明:温度越高放氧越快,但温度越高氧气的饱和量越低,气体外溢,故测出的溶解氧浓度数值较低;采用滤纸片法和二倍稀释法测定过氧乙酸和3种常用杀菌剂对6种常见水产病原菌(副溶血弧菌、维氏气单胞菌、嗜水气单胞菌、溶藻弧菌、沃氏葡萄球菌和腐生葡萄球菌)的抑菌效果,结果显示,抑菌效果依次为恩诺沙星过氧乙酸聚维酮碘高锰酸钾;对暂养的黄丝藻藻华进行毒杀,结果显示,随着时间的延长,加入高浓度过氧乙酸的试验组水体开始混浊,藻丝体开始断裂,叶绿素a含量减少;各时段下,过氧乙酸浓度组叶绿素a含量明显低于对照组(P0.05),随着时间的延长各浓度组超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量均呈先增长后下降的趋势,说明黄丝藻藻丝体受到了过氧乙酸的破坏,开始解体甚至死亡。研究表明,在水产养殖池塘中使用过氧乙酸,增氧、抑菌、抑藻效果明显。     

放线菌制剂对番茄PPO活性及生物量的影响

【目的】研究2种放线菌制剂对供试番茄生物量、保护性酶活性的影响,探索生防菌剂的防病促生机理。【方法】以Act1(加州链霉菌Streptomyces californicus)、Act2(假刺孢链霉菌Streptomyces pseudovenezuelae)、Act11(肉质链霉菌Streptomyces carnosus)、Act12(密旋链霉菌Streptomyces pactum)及Act8(1株未定种的链霉菌Streptomyces sp.)5种放线菌为材料,制成菌剂BCA1(由放线菌Act1、Act11和Act12按1∶1∶1的质量比混合而成)和菌剂BCA2(由Act1、Act2和Act8按1∶1∶1的质量比混合而成)2种放线菌制剂。以不接菌为对照,分别将BCA1和BCA2进行稀释后对番茄进行蘸根处理,采用常规称质量及PPO酶活性测定法分别对番茄生物量及叶片PPO酶活性进行测定。【结果】2种放线菌制剂均使苗期番茄叶片PPO活性降低,根系PPO活性升高,随着植株生长期的延长,菌剂对PPO活性的影响逐渐减小。②接种2种放线菌制剂对番茄生长均有明显的促进作用,BCA1使番茄的总生物量、茎质量、根系质量及须根质量分别增加了44.27%,47.38%,14.58%及52.85%;BCA2使番茄的总生物量、茎质量、根系质量及须根质量分别增加了46.87%,47.89%,42.63%及93.65%。【结论】接种放线菌制剂对番茄有明显的促生作用,可促进根系生长,增加生物量,并提高根系PPO活性,进而增强番茄根系的免疫力和抗病性。     

乌龙岭龙眼果皮的PPO特性及活性抑制

为探明乌龙岭龙眼贮藏保鲜过程中的褐变问题,以C6H6O2为底物,采用分光光度法研究了底物浓度对龙眼果皮PPO活性的影响规律.采用正交试验方案,分析了不同抑制剂、pH值和温度对乌龙岭龙眼果皮PPO活性的影响.结果表明,龙眼果皮褐变反应的动力学符合米氏方程,米氏常数为0.054 mol.L-1,最大反应速度为1.428×102U.m in-1.适宜的抑制剂可有效延缓龙眼果皮的褐变,保持龙眼质量.在相同条件下,Na2S2O3抑制效果最好.此外,还对影响龙眼果皮PPO活性的因素进行了优化.