吗啡降低大鼠脊髓内cAMP的含量

有资料表明,吗啡或脑啡肽可影响脑内 cAMP 与 cGMP 的含量,但对脊髓内 cAMP 与cGMP 的含量有何影响,未见报道。本实验采用放射免疫分析(RIA)方法研究的结果表明,吗啡可使大鼠离体与在体脊髓内 cAMP 的含量明显降低;而对脊髓内 cGMP 的含量则无明显影响;纳洛酮可特异阻断吗啡对脊髓内 cAMP 含量的抑制效应。提示:吗啡的上述作用是通过大鼠脊髓内阿片受体所介导。脑和脊髓内 cAMP 含量的变化可能部分介导了吗啡作用的中枢机制。     

Role of the body in primary signal processing by the electroreceptor system of the skate

Using a mathematical modeling technique, possible spatial mechanisms of processing information by the ampullae of Lorenzini were investigated in the skate during detection of the dipole electric field corresponding in the first approximation to the bioelectric fields of marine vertebrates and invertebrates. Stationary voltage distribution in the inhomogeneous environment was calculated numerically. An unlimited volume of seawater was used as the environment into which a slim disk was placed simulating the body of the fish, which served to create inhomogeneity. When the dipole axis was on the same plane as the disk, distortion in the voltage distribution was negligible. On occasions when the dipole was perpendicular to the plane of the disk, the electrical field energy absorbed by ampullary groups decreased significantly. Calculations suggested that by reorienting its body the fish is able to phase out signals coming from dipoles with their axes on different planes from that of the skate's body.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 17, No. 5, pp. 660–665, September–October, 1985.     

Comparison of the structure of two cardiac troponin T isoforms.

Two isoforms of troponin T have been isolated from bovine cardiac muscle. One isoform has an Mr of 31000 and a pI at about 7.1, the corresponding values for the second isoform being 33000 and 6.5. Both isoforms have identical C- and N-terminal sequences, and, according to the data from tryptic-peptide mapping, a similar structure of the central and C-terminal domains. The large N-terminal peptides of troponin T isoforms differ in the content of glutamine/glutamic acid and alanine. It is concluded that the isoform with Mr 33000 has an additional peptide enriched with glutamic acid and alanine that is inserted between the N-terminal pentapeptide and the cysteine located 40-60 residues from the N-terminus.     

Introduction of a nitrogen-fixing cyanobacterium into tobacco shoot regenerates

Tobacco (Nicotiana tabacum L.) shoots associated with the nitrogen-fixing cyanobacterium Anabaena variabilis Kütz. (ATCC 29413) were regenerated in mixed cultures of tobacco callus and the cyanobacterium. The cyanobacteria were localized inside the tissues as well as on the surface of regenerated shoots, formed heterocysts, and were capable of acetylene reduction.     

Some properties of cardiac troponin T structure.

Troponin T is eluted in multiple peaks when the whole bovine cardiac troponin complex is subjected to DEAE-cellulose chromatography in the presence of 8 M-urea. The heterogeneity observed is due to the presence of two forms of troponin T, differing in their Mr values, amino acid content, degree of phosphorylation and aggregation. Cardiac troponin T contains up to 0.8 mol of phosphate/mol of protein. Rabbit skeletal-muscle troponin T kinase phosphorylates the single site located in the N-terminal pentapeptide of cardiac troponin T. The composition of this peptide, (Ser,Asx,Glx,Glx)Val, is similar to that of skeletal-muscle troponin T. The single thiol group of cardiac troponin T is located some 50-70 residues from the N-terminus. The C-terminal sequence of cardiac troponin T is Trp-Lys, i.e. as is the case of skeletal-muscle troponin T.     

厚孢孔菌属一新种

本文报道了厚孢孔菌属(Pachykytospora)的一个新种,即大厚孢孔菌Pachykytospora major G.Y.Zheng et Bi和一个国内新记录:瘤厚孢孔菌Pachykytospora tuberculosa(DC.:Fr.)Kotl.et Pouz.。     

中国瘤螩属一新种记述──（螩目：杆螩科）

瘤属ＤａｔａｍｅｓＳｔａｌ１８７５隶属于杆科Ｂａｃｉｌｌｉｄａｅ、异翅亚科Ｈｅｔｅｒｏｐｔｅｒｙｇｉｎａｅ,已知９种,均分布在东南亚地区。Ｓｈｉｒａｋｉ（１９３５）报道我国台湾有１种蒙霍瘤Ｄ．ｍｏｕｈｏｔｉ,（Ｂａｔｅｓ１８６５）,该种模式产地为柬埔寨。本文记述的瘤属在中国大陆是首次报道。模式标本保存在中国科学院上海昆虫研究所。     

应激时大鼠血,脑,心血管,肾上腺血管紧张素Ⅱ含量的变化

本实验观察了三种应激情况下,大鼠血浆,下丘脑,延髓,心肌,血管及肾上腺组织血管紧张素Ⅱ（ＡⅡ）含量,以及血浆皮质酮含量的。应激方式分为急性应激（冷水游泳,断肢创伤）与慢性应激（寒冷环境刺激）。结果表明：急性应激动物血中ＡⅡ剧烈增高,游泳组达对照值的９００％,创伤组增至３９０％,慢性寒冷组增至１３４％;而组织ＡⅡ除肾上腺外,则以慢性寒冷组增加最明显,游泳组次之,创伤组无明显变化。血浆皮质酮各组均显著