Transmitter-Induced Calcium Responses Differ in Astrocytes Acutely Isolated from Rat Brain and in Culture

Abstract: Glial fibrillary acid protein (GFAP)-positive astrocytes isolated from the cerebral cortices of 3–10-day-old rats frequently showed increased intracellular Ca²⁺ concentration responses to l -glutamate and glutamate analogues. However, few of the acutely isolated cells responded to ATP, and no such cells responded to serotonin [5-hydroxytryptamine (5-HT)]. The same cell that failed to respond to ATP or 5-HT often responded to glutamate. Culturing acutely isolated cells in media containing horse serum decreased Ca²⁺ responses to glutamate but increased the responses to ATP and induced responses to 5-HT. In primary cultures prepared from the cerebral cortices of 1-day-old rats and cultured in horse serum, fewer of the cells responded to glutamate, but almost all cells responded to ATP and 5-HT. The lack of, or limited response to, 5-HT or ATP in the acutely isolated cells seems unlikely to be due to selective damage to the respective receptors because acutely isolated GFAP-negative cells showed responses to ATP, several different proteases and mechanical dissociation yielded cells that also responded to glutamate but not to ATP, and exposure of primary cultures to papain did not abolish Ca²⁺ responses to several transmitters. The responses of the acutely isolated cells to glutamate but limited or lack of responses to ATP and 5-HT also correspond to what has been seen so far for astrocytes in situ. Thus, the present studies provide direct evidence that some of the receptors seen in primary astrocyte cultures may reflect a response to culture conditions and that, in the context of the relevant information so far available, acutely isolated astrocytes seem to reflect better the in vivo state.     

为害枣树一菱纹叶蝉新种

为害枣树一菱纹叶蝉新种蔡平（安徽农学院园艺系合肥２３００３６）崔士英（河北师范大学生物系石家庄０５００１６）葛钟麟（安徽农学院植保系合肥２３００３６）菱纹叶蝉属（Ｈｉｓｈｉ。。ｏｎｕｓＩｓｈｉｈａｒａ。１９５３）隶属于同翅目（ＨｏｍｏＰｔｅｒａ）ｎ十...     

高粱泡的生长调控与结实状况

高粱泡(Rubus lambertionus Ser.)是一种有利用价值的野生果树资源。其优点为:(1)结果早,产量高,亩产量可达500kg以上;(2)适应性广,耐瘠薄,是开发利用低山丘陵的优良资源植物;(3)果实营养丰富,酸味纯正,尤其是所含红色素稳定性好,是加工果汁饮料的优质添加剂;(4)果实采收期在11月中旬到12月底,此时气温低,有利于浆果加工和贮藏,并可利用农闲季节的劳动力。上述特点表明,高粱泡有很好的开发利用前景。但本种在野生状态下蔓生性强,多刺,并具有枝顶生根的习性,因而树形紊乱而松散,栽培时搭架困难,植株占地面积大,而单位面积产量不易提高。为了便于操作管理和提高产量,减少栽培成本,增进经济效益,我们于1990～1991年进行了生长和株形调控试验,     

Characterization of the IS895 family of insertion sequences from the cyanobacterium Anabaena sp. strain PCC 7120.

A family of repetitive elements from the cyanobacterium Anabaena sp. strain PCC 7120 was identified through the proximity of one element to the psbAI gene. Four members of this seven-member family were isolated and shown to have structures characteristic of bacterial insertion sequences. Each element is approximately 1,200 bp in length, is delimited by a 30-bp inverted repeat, and contains two open reading frames in tandem on the same DNA strand. The four copies differ from each other by small insertions or deletions, some of which alter the open reading frames. By using a system designed to trap insertion elements, one of the elements, denoted IS895, was shown to be mobile. The target site was not duplicated upon insertion of the element. Two other filamentous cyanobacterial strains were also found to contain sequences homologous to IS895.     

Cyclic GMP-dependent protein kinase stimulates the plasma membrane Ca2+ pump ATPase of vascular smooth muscle via phosphorylation of a 240-kDa protein.

The plasma membrane Ca2+ pump ATPase from porcine aorta was isolated by the calmodulin affinity chromatographic method of Kosk-Kosicka et al. (Kosk-Kosicka, D., Scaillet, S., and Inesi, G. (1986) J. Biol. Chem. 261, 3333-3338). Its activity was restored by adding either phosphatidylcholine or phosphatidylserine. Cyclic GMP-dependent protein kinase (G-kinase) stimulated the enzyme in a concentration-dependent manner. However, phosphatidylinositol kinase (PI-kinase) activity was not detected in the enzyme preparation, and the presence of phosphatidylinositol was not necessary for stimulation by G-kinase. Furthermore, adenosine, a potent PI-kinase inhibitor, did not affect the stimulation. The enzyme preparation contained three major proteins, with molecular masses of 240, 145, and 135 kDa, as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The 240- and 135-kDa proteins were phosphorylated in association with the stimulation by G-kinase, but only the phosphorylation of the 240-kDa protein was dependent on the G-kinase concentration. A purified enzyme without the 240-kDa protein, prepared by our previous method (Imai, S., Yoshida, Y., and Sun, H.-T. (1990) J. Biochem. (Tokyo) 107, 755-761), was not activated by G-kinase. Immunoblotting with an antibody against the human erythrocyte Ca2+ pump revealed that the 135-kDa protein corresponded to one of the isoforms of the plasma membrane Ca2+ pump. These results suggest that the phosphorylation of the 240-kDa protein is responsible for stimulation of the plasma membrane Ca2+ pump ATPase by G-kinase.     

草鱼出血病病毒对其它鱼的感染性研究

用草鱼出血病病鱼分离出的草鱼出血病病毒(Grass carp hemorrhage virus,GCHV)感染其它常见鱼并用ELISA方法检查感染鱼组织提取液,结果表明:青鱼、鲢鱼、布氏鳌条对GCHV抗体呈阳性反应;鲤鱼、鳙鱼、鲫鱼、团头鲂、泥鳅则呈阴性反应。综合感染鱼发病症状及死亡特征,初步认为:青鱼对GCHV是易感的,GCHV能在鲢鱼、布氏蟹条体内增值,但毒力较低,鳙鱼、鲫鱼、团头鲂、鲤鱼、泥鳅能抗GCHV感染。     

Proton resonance assignments for Pseudomonas aeruginosa ferrocytochrome c-551.

A comparison between two sets of resonance assignments for ferrocytochrome c-551 from Pseudomonas aeruginosa reveals that major differences can be explained by pH effects. In turn, these reveal side chain protonation events in c-551 that markedly influence spectra. The behavior of resonances in a homologous protein from Pseudomonas stutzeri help to clarify ambiguities in the P. aeruginosa case. A corrected and completed set of proline assignments is presented. Labile side chain protons in residue 47, which hydrogen bonds to the inner heme propionate, appear to be in fast exchange with the solvent.