Synaptic transmission between photoreceptors and horizontal cells in the turtle retina

Low calcium, high magnesium, and cobalt hyperpolarize the horizontal cell membrane and suppress the response to light, but only partially affect the response of receptor cells. These observations are consistent with the interpretation that a depolarizing transmitter is released by photoreceptors in darkness. The hyperpolarizing response to light of the horizontal cells would then result from a reduction in the amount of transmitter released.     

Concanavalin A alters synaptic specificity between cultured Aplysia neurons

Factors that regulate synaptic specificity were investigated with Aplysia buccal and bag cell neurons in primary cell culture. In the presence of fetal calf serum electrical synapses are formed between buccal-buccal or bag-bag cell pairs, but not between buccal-bag cell pairs. Instead, buccal neurons make inhibitory chemical synapses on bag cells. However, in the presence of nanomolar concentrations of the lectin concanavalin A this pattern changes, such that more than 75 percent of buccal-bag pairs exhibit electrical synapses and the frequency of occurrence of buccal-bag chemical synapses is reduced. Such changes in synaptic specificity may be important in determining the types of synapses formed during neuronal development and neurite regeneration.     

Specialized inhibitory synaptic actions between nearby neocortical pyramidal neurons

We found that, in the mouse visual cortex, action potentials generated in a single layer-2/3 pyramidal (excitatory) neuron can reliably evoke large, constant-latency inhibitory postsynaptic currents in other nearby pyramidal cells. This effect is mediated by axo-axonic ionotropic glutamate receptor-mediated excitation of the nerve terminals of inhibitory interneurons, which connect to the target pyramidal cells. Therefore, individual cortical excitatory neurons can generate inhibition independently from the somatic firing of inhibitory interneurons.     

Gallamine (Flaxedil) and synaptic transmission in the spinal cord

A paralyzing dose of gallamine (Flaxedil) (1 to 2 milligrams per kilogram of body weight) has no effect on synaptic transmission in the cat's spinal cord. In spinal cats ventilated with oxygen, we stimulated a dorsal spinal root and recorded the compound ventral root potential. The reflex potential was not affected by 6.25 milligrams of gallamine per kilogram. Giving 12.5 milligrams of gallamine per kilogram had no significant effect on the monosynaptic spike height, but the polysynaptic response rose briefly to 12 percent above control. Increased magnitude of the polysynaptic response appeared related to a concomitant rise in blood pressure.     

通过微量细胞鉴定快速生产基因编辑猪

目的建立快速筛选猪的基因编辑阳性成纤维细胞系的方法以提高利用体细胞核移植产生基因编辑克隆猪的效率。方法通过PCR、T7EN1酶切和Sanger测序分析不同数量的已知猪基因编辑阳性细胞(20、50、100、150和200个细胞)的基因型,确定最小细胞数用于鉴定未知的基因编辑阳性细胞系以证明该方法的可行性。结果除20细胞组外,其他所有细胞组中均扩增出2条明显的T7EN1酶切条带(175和555 bp)。定量数据显示：20细胞组和50细胞组之间的条带灰度值存在极显著差异(P<0.01),因此50细胞可用于基因编辑阳性细胞系鉴定。利用CRISPR/Cas9系统构建IPO13打靶载体,转染猪胎儿成纤维细胞形成细胞克隆点后计数50个细胞来筛选阳性细胞系,再通过体细胞核移植快速生产了IPO13敲除猪,从而证实通过微量细胞鉴定快速生产基因编辑猪的可行性。筛选基因编辑阳性细胞系的一般方法大约需要33.7 d,新建立的方法细胞筛选周期仅为18.9 d (减少15 d),获得阳性细胞系的成功率也提高了约4倍。结论本研究建立了一种通过微量细胞鉴定快速生产基因编辑克隆猪的方法,该方法可行可靠。     

Control of glutamate clearance and synaptic efficacy by glial coverage of neurons

Analysis of excitatory synaptic transmission in the rat hypothalamic supraoptic nucleus revealed that glutamate clearance and, as a consequence, glutamate concentration and diffusion in the extracellular space, is associated with the degree of astrocytic coverage of its neurons. Reduction in glutamate clearance, whether induced pharmacologically or associated with a relative decrease of glial coverage in the vicinity of synapses, affected transmitter release through modulation of presynaptic metabotropic glutamate receptors. Astrocytic wrapping of neurons, therefore, contributes to the regulation of synaptic efficacy in the central nervous system.     

Contributions of two types of calcium channels to synaptic transmission and plasticity

In Aplysia sensory and motor neurons in culture, the contributions of the major classes of calcium current can be selectively examined while transmitter release and its modulation are examined. A slowly inactivating, dihydropyridine-sensitive calcium current does not contribute either to normal synaptic transmission or to any of three different forms of plasticity: presynaptic inhibition, homosynaptic depression, and presynaptic facilitation. This current does contribute, however, to a fourth form of plasticity--modulation of transmitter release by tonic depolarization of the sensory neuron. By contrast, a second calcium current, which is rapidly inactivating and dihydropyridine-insensitive, contributes to release elicited by the transient depolarization of an action potential and to the other three forms of plasticity.     

Epilepsy-related ligand/receptor complex LGI1 and ADAM22 regulate synaptic transmission

Abnormally synchronized synaptic transmission in the brain causes epilepsy. Most inherited forms of epilepsy result from mutations in ion channels. However, one form of epilepsy, autosomal dominant partial epilepsy with auditory features (ADPEAF), is characterized by mutations in a secreted neuronal protein, LGI1. We show that ADAM22, a transmembrane protein that when mutated itself causes seizure, serves as a receptor for LGI1. LGI1 enhances AMPA receptor-mediated synaptic transmission in hippocampal slices. The mutated form of LGI1 fails to bind to ADAM22. ADAM22 is anchored to the postsynaptic density by cytoskeletal scaffolds containing stargazin. These studies in rat brain indicate possible avenues for understanding human epilepsy.     

Synaptic connections between a transplanted insect ganglion and muscles of the host

When a metathoracic ganglion from one cockroach (Periplaneta americana) is transplanted into the coxa of another cockroach, it innervates only those leg muscles that have been previously denervated. The transplanted ganglion evokes hyperpolarizing synaptic potentials in the host muscles that it innervates. These potentials are correlated with twitching of the host limb.     

Simultaneous expression of globin genes for embryonic and adult hemoglobins during mammalian ontogeny

The dominant hemoglobin of the adult hamster was detected in yolk-sac erythroid cells, and its identity was confirmed by peptide mapping and by analysis of relevant peptides. Both the presence and active synthesis of two embryonic hemoglobins presumed to exist only in yolk-sac erythroid cells were detected in neonatal liver and spleen. Thus the time span of expression of both embryonic and adult globin genes during mammalian ontogeny may be considerably broader than presently believed.     

枯叶蛱蝶非滞育成虫与越冬成虫核酸含量比较

为深入了解枯叶蛱蝶滞育机理,利用比色法测定了非滞育成虫和越冬成虫不同发育阶段的RNA和DNA含量.结果表明,非滞育成虫RNA含量为21.0687～31.9513μg/mg,DNA含量为1.1677～1.2817μg/mg;越冬成虫RNA含量为10.0967～14.3193 μg/mg,DNA含量为1.3673～2.7610 μg/mg.核酸含量变化与发育阶段有关,与生殖系统发育关系密切.     

国际与国内棉花价格的非线性空间传导研究

随着国内棉花市场开放程度增加,国内外棉花价格联动性增强,明晰国内外棉花价格传递机制尤为重要。采用2007年4月6日至2018年7月6日的周数据,运用MSIH(3)-VAR(P)模型和脉冲响应分析中国棉花期现货市场、国际期货市场之间的相互影响以及非线性空间传导关系。实证结果表明,国际棉花期货市场、中国棉花期现货市场价格波动存在三区制的非线性传导效应,需要重视棉花补贴政策对市场分区带来的影响。中国棉花期现货市场对国际棉花市场波动的响应相对较弱,存在削弱影响的因素,而且受国际棉花期货市场价格的引导;中国棉花期货市场对现货市场的价格有更强的响应,现货市场价格识别期货价格信息能力相对较弱,但趋向于引领期货市场的价格,中国棉花的期货市场仍有待进一步的开发与完善。这些研究结论与构建的非线性分析棉花价格波动模型,可以为政策制定者和棉花产业相关利益群体提供决策参考。     

Electrotonic junctions between teleost spinal neurons: electrophysiology and ultrastructure

Electrotonic transmission between spinal neurons is correlated with distinctive apposition of cell processes involving membrane fusion. In the same neurons, postsynaptic potentials appear to arise at typical synaptic knobs where there is an intercellular space.     

Relation between work and phosphate metabolite in the in vivo paced mammalian heart

Nuclear magnetic resonance (NMR) spectroscopy was used to monitor, on a beat-to-beat basis, the concentration of creatine phosphate and adenosine triphosphate during alterations in the work output of canine hearts in vivo. Over a wide range of rate-pressure products (5,000 to 25,000 mmHg/min), the relative amounts of creatine phosphate and adenosine triphosphate within the heart remained constant. The relative concentration of free adenosine diphosphate was calculated under the reasonable assumption that the creatine kinase-catalyzed reaction is near equilibrium in this tissue. The free concentration of adenosine diphosphate also did not change over this range of rate-pressure products. The data demonstrate that the concentration of these compounds is highly regulated in vivo and suggest that factors other than their concentration may be involved in the modulation of steady-state myocardial work output with oxygen consumption.     

Viral shedding and transmission between hosts determined by reovirus L2 gene

Two reovirus isolates (type 1 Lang and type 3 Dearing) differ in their transmissibility between littermates of newborn mice. They also differ in the amounts of virus excreted by the gastrointestinal tract. With the use of reassortant viruses, these properties were mapped to the L2 gene. Thus environmental spread of reovirus is a genetic property.     

农村气象信息服务于“三农”的思考

气象事业与"三农"工作密切相关,气象信息对农村防灾减灾具有十分重要作用.如何保障气象信息有效传播,是建设社会主义新农村的重要举措之一,也是气象部门义不容辞的责任.分析了气象信息服务于农村的现状,影响农村气象信息服务"三农"的主要因素及农村对气象信息服务的需求,对促进农村气象信息有效传播提出了建议.     

Relationship between clinical signs and transmission of an infectious disease and the implications for control

Control of many infectious diseases relies on the detection of clinical cases and the isolation, removal, or treatment of cases and their contacts. The success of such "reactive" strategies is influenced by the fraction of transmission occurring before signs appear. We performed experimental studies of foot-and-mouth disease transmission in cattle and estimated this fraction at less than half the value expected from detecting virus in body fluids, the standard proxy measure of infectiousness. This is because the infectious period is shorter (mean 1.7 days) than currently realized, and animals are not infectious until, on average, 0.5 days after clinical signs appear. These results imply that controversial preemptive control measures may be unnecessary; instead, efforts should be directed at early detection of infection and rapid intervention.     

Transmission between pairs of hippocampal slice neurons: quantal levels, oscillations, and LTP

Long-term potentiation (LTP) of synaptic transmission after coincident pre- and postsynaptic activity is considered a cellular model of changes underlying learning and memory. In intact tissue, LTP has been observed only between populations of neurons, making analysis of mechanisms difficult. Transmission between individual pre- and postsynaptic hippocampal cells was studied, suggesting quantal amplitude distributions with little variability in quantal size. LTP between such pairs is manifested by large, persistent, and synapse-specific potentiation with a shift in amplitude distribution that suggests presynaptic changes. Oscillations in amplitude of transmission, apparently of presynaptic origin, are common and can be triggered by LTP.