Nerve growth factor: relationship to the cyclic AMP system of sensory ganglia

Nerve growth factor and N(6),O(2)' dibutyryl adenosine 3',5'-monophosphate both stimulate neurite elongation by explanted ganglia. However, the addition of nerve growth factor does not lead to increased amounts of adenosine 3',5'-monophosphate in intact ganglia, nor does it stimulate adenylate cyclase activity in broken ganglia cells.     

Substance P: does it produce analgesia or hyperalgesia?

In the hot plate test, substance P given intravenously at doses of 5 x 10-5 and 5 x 10-4 gram per kilogram caused analgesia, while lower doses caused hyperalgesia. The influence of substance P on nociception depended on the individual mouse's sensitivity to pain (control response latency). Analgesia was produced by substance P administered to mice with high sensitivity to thermic stimulation, whereas hyperalgesia occurred in mice whose control latencies were longer than normal. This result is interpreted as an indication that substance P is capable of normalizing responsiveness to pain and could be classified as a regulatory peptide.     

Substance P activation of rheumatoid synoviocytes: neural pathway in pathogenesis of arthritis

Several clinical features are consistent with nervous system involvement in the pathogenesis of rheumatoid arthritis. The neuropeptide substance P is one possible mediator of this interaction, since it can be released into joint tissues from primary sensory nerve fibers. The potential effects of the peptide on rheumatoid synoviocytes were examined. The results show that substance P stimulates prostaglandin E2 and collagenase release from synoviocytes. Furthermore, synoviocyte proliferation was increased in the presence of the neuropeptide. Similar effects were observed with a truncated form of substance P. Synoviocytes were sensitive to very small doses of the neuropeptide (10(-9) M), and its effects were inhibited by a specific antagonist. Thus, the specific stimulation of synoviocytes by the neuropeptide substance P represents a pathway by which the nervous system might be directly involved in the pathogenesis of rheumatoid arthritis.     

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.     

Substance P and cholecystokinin-like peptides in Helix neurons and cholecystokinin and serotonin in a giant neuron

Immunohistochemical procedures revealed that the serotonin-containing cell situated in each metacerebral ganglion of the snail Helix also contains a cholecystokinin-like peptide, but is devoid of substance P. In radioimmunoassays the cholecystokinin-like material showed similarities to the carboxy terminal regions of mammalian cholecystokinin and gastrin. Since much is known about the morphology and synaptic connections of this serotonin neuron, the role of the cholecystokinin-like peptides can now be investigated by neurophysiological methods, thus opening the way to discovering whether a neuron can use more than one transmitter.     

Acetylcholine: possible neuromuscular transmitter in Crustacea

The tonic flexor muscles of the crayfish abdomen respond with a large depolarizing potential to acetylcholine iontophoresed onto a neuromuscular Junction, but not to glutamate. Excitatory junctional potentials are abolished by d-tubocurarine and enhanced by a cholinesterase inhibitor. The membrane is depolarized and the junctional potentials are desensitized by excess acetylcholine. Thus acetylcholine is thought to be the neuromuscular transmitter.     

Substance P analog, DiMe-C7: evidence for stability in rat brain and prolonged central actions

A metabolically protected analog of substance P, [pGlu5-MePhe8-MeGly9]SP(5-11) (DiMe-C7), was approximately equipotent with substance P in causing increased locomotor activity after microinfusion into the ventral tegmental area of rat brain, but the effects of DiMe-C7 on behavior were considerably prolonged. There was little metabolic degradation of tritiated DiMe-C7 for up to 1 hour after infusion, whereas tritiated substance P was completely degraded within 10 minutes.     

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.     

Dopamine: its occurrence in molluscan ganglia

Fluorometric and paper chromatographic evidence indicates that dopamine is the only catecholamine present in the ganglia of a number of lamellibranch and gastropod species.     

试验性趾叶炎小鼠肠组织中P物质的表达

[目的]为动物趾叶炎的预防和治疗提供免疫学基础。[方法]对昆明种小白鼠注射二磷酸组织胺制备趾叶炎小鼠病理模型,以注射生理盐水为对照。分别于给药后2、14、24、48、72 h及15、30 d取小鼠3~5 mm长的小肠组织块,检测肠组织中炎性细胞、杯状细胞、肥大细胞及其脱颗粒数、P物质表达水平的动态变化。[结果]趾叶炎小鼠的肠腺结缔组织内及其绒毛上P物质表达异常丰富,且P物质呈单根或片状走行,并与肥大细胞串联及相邻排列,随给药时间的延长,P物质表达逐渐增强,肥大细胞及其脱颗粒数也急剧增多 炎性细胞、杯状细胞、腺体数量与肥大细胞的变化趋势一致 给药72 h后,血管内壁出现裂隙,肠粘膜出现水肿。[结论]肥大细胞参与小鼠趾叶炎的发病过程,并影响小鼠肠粘膜的通透性。     

Gelatin: a poor substrate for a mammalian collegenase

A rabbit tumor collagenase was purified more than 5000-fold. In this form it degrades native collagen in helical conformation at 37 degrees C, pH 7.6, into two fragments, but it had little capacity to cleave gelatin, an indication of the importance of higher-order structure of substrate for this enzyme in pure form. It is likely that, in vivo, enzymes other than collagenase degrade gelatin polypeptides produced by primary collagenolysis.     

Cyclic nucleotide phosphodiesterase: high activity in a mammalian photoreceptor

Purified outer segments of bovine rods exhibit phosphodiesterase activity against adenosine and guanosine cyclic 3',5'-monophosphates (cyclic AMP and cyclic GMP). The enzyme hydrolyzed cyclic GMP more rapidly than cyclic AMP at low substrate concentrations. The presence of high phosphodiesterase activity in this highly specialized organelle suggests that this enzyme may function in control of cyclic nucleotide concentration during visual excitation or adaptation.     

低氧条件下甘肃鼢鼠鼻黏膜内含SP及CGRP的免疫反应纤维长度变化

运用免疫组织化学方法对比了常氧条件下与低氧条件下甘肃鼢鼠鼻黏膜内含P物质(SP)及降钙素基因相关肽(CGRP)的神经纤维平均长度的变化情况。结果表明,甘肃鼢鼠在低氧条件下,鼻腔嗅黏膜内含SP及CGRP的免疫反应纤维的平均长度与常氧条件下的比率分别为0.97和1.09,呼吸黏膜的比率分别为1.20和1.22,明显小于SD大鼠的相应比率,但差异均未达极显著水平(0.01相似文献   

Vasoactive intestinal peptide: a possible transmitter of nonadrenergic relaxation of guinea pig airways

Vasoactive intestinal peptide, a smooth-muscle relaxant neuropeptide with neurotransmitter properties, was relaxed during electrical field stimulation of guinea pig trachea. The amount released correlated with the degree of relaxation, and the release was blocked by tetrodotoxin. Prior incubation of the trachea with antiserum to vasoactive intestinal peptide reduced the relaxation. Thus vasoactive intestinal peptide may mediate the nonadrenergic relaxation of tracheal smooth muscle.     

Melatonin: a coordinating signal for mammalian reproduction?

There is a daily rhythm in the production of the pineal hormone melatonin in all mammalian species. Production is stimulated by darkness and inhibited by light. This provides a signal reflecting the changing environmental lighting cycle. In seasonally breeding mammals that use changes in the photoperiod to time their reproductive cycles, temporal signals to the reproductive system are controlled by the daily rhythm in melatonin production.     

RNA-DNA hybridization: demonstration in a mammalian system of competition by preincubation

Nonspecific intermolecular interactions obscure the interpretation of competition experiments involving hybridization of DNA and RNA in mammalian systems when the labeled RNA/DNA ratio is low. The effect of these interactions can be minimized by choosing a sufficiently high ratio of labeled RNA/DNA. No serious effect of nonspecific interactions is observed in bacteriophage systems, even at very low labeled RNA/DNA ratios.     

Centrifugation of mammalian cells on gradients: a new rotor

A short-arm rotor increases separation of viable mammalian cells, from mixtures, by low-speed centrifugation; continuous Ficoll density gradients in tissue-culture media are used. We describe the theory and experimental demonstration of the superior separation achieved with this new rotor.     

Anabaena sensory rhodopsin: a photochromic color sensor at 2.0 A

Microbial sensory rhodopsins are a family of membrane-embedded photoreceptors in prokaryotic and eukaryotic organisms. Structures of archaeal rhodopsins, which function as light-driven ion pumps or photosensors, have been reported. We present the structure of a eubacterial rhodopsin, which differs from those of previously characterized archaeal rhodopsins in its chromophore and cytoplasmic-side portions. Anabaena sensory rhodopsin exhibits light-induced interconversion between stable 13-cis and all-trans states of the retinylidene protein. The ratio of its cis and trans chromophore forms depends on the wavelength of illumination, thus providing a mechanism for a single protein to signal the color of light, for example, to regulate color-sensitive processes such as chromatic adaptation in photosynthesis. Its cytoplasmic half channel, highly hydrophobic in the archaeal rhodopsins, contains numerous hydrophilic residues networked by water molecules, providing a connection from the photoactive site to the cytoplasmic surface believed to interact with the receptor's soluble 14-kilodalton transducer.     

稻瘟病菌一假定几丁质酶在毕赤酵母中的表达

本研究从稻瘟病菌菌株Guy11中提取总RNA,利用RT-PCR方法扩增到一假定几丁质酶基因MGG_08054.6的cDNA序列,将其亚克隆至带有His-tag标签的酵母表达载体pPIC3.5K中,构成重组质粒pPIC3.5K-ws,电击转化至毕赤酵母菌菌株GS115,通过MD-MM平板筛选及PCR验证获得重组酵母转化子GS115-PICH-ws;阳性转化子在甲醇诱导下,成功分泌出重组蛋白.SDS-PAGE分析表明,重组蛋白分子质量为48 ku,与其理论计算值基本相符;Ni-NTA法分离纯化后的重组蛋白经DNS法测定具有几丁质酶活性.