白细胞介素－2受体γ链研究新进展

白细胞介素－2受体γ链（interleukin-2 receptorγchain,IL-2Rγc）是约3年前发现的IL-2受体亚单位之一,它不但参与高、中亲和力IL-2R的形成,而且作为细胞因子受体超家族成员参与IL－4、IL－7、IL－9和IL－15受体以及可能的IL－13受体功能性复合物的形成．IL-2Rγc基因结构与功能和蛋白质分子结构以及染色体定位已阐明．IL-2Rγc及信号传导的异常导致人类Ｘ染色体连锁重度联合免疫缺陷病(X-linked severe combined immunodeficiency XSCID)．因此,阐明IL-2Rγc在生理及病理状态下的生物学作用,对了解淋巴细胞的生长发育和分化成熟、免疫应答及其调控等问题都有重要的指导意义．     

大鼠正中神经一级传入纤维在脊髓胶状质定位投射的定量分析——FRAP法

本文用抗氟化物酸性磷酸酶(FRAP)法和显微测量,对大鼠正中神经一级传入纤维在脊髓胶状质(SG)的定位投射进行了定量分析.大鼠正中神经向SG的纵向投射主要为C_5～T_1.C_5～T_1各节段SG水平向眉毛状反应带所测均值(mm)分别为0.888、0.935、0.957、0.905和 0.776,而正中神经向C_5～T_1各节段SG水平向投射所测均值(mm)分别在0～0.204、0～0.303、0～0.409、0～0.432和0～0.336的范围,这显示了正中神经投射区均位于SG的内侧带和部分中间带.     

An unusual Group 2 LEA gene family in citrus responsive to low temperature

Six cDNAs representing unique cold-induced sequences have been cloned from the hardy citrus relative Poncirus trifoliata. Among these, pBCORc115 and pBCORc119 were found to belong to the same gene family. Sequencing data indicated that pBCORc115 and pBCORc119 each contained an open reading frame, coding for a 19.8 kDa protein (COR19) and a smaller 11.4 kDa protein (COR11) respectively. Inspection of the deduced amino acid sequences revealed three large repeats in COR19, but only one was present in the COR11. Two elements: a Q-clustered tract and a K-rich motif were identified in each repeat. The K-rich motifs were similar to those of cotton D-11 and Group 2 LEA proteins. A Serine-cluster, a common feature in many Group 2 LEA-like proteins, was also found in these proteins, but it was in an unusual position at the carboxy-terminus. A bipartite motif of basic residues, similar to known nuclear targeting sequences, was also present in COR19 and COR11, suggesting that members of this protein family may have a nuclear targeting function. The expression of COR19 mRNA in response to cold acclimation, drought, flooding, and salinization was examined. COR19 expression in leaf tissue was induced in response to cold acclimation, but repressed during drought and flooding stress.     

The serum response factor nuclear localization signal: general implications for cyclic AMP-dependent protein kinase activity in control of nuclear translocation.

We have identified a basic sequence in the N-terminal region of the 67-kDa serum response factor (p67SRF or SRF) responsible for its nuclear localization. A peptide containing this nuclear localization signal (NLS) translocates rabbit immunoglobulin G (IgG) into the nucleus as efficiently as a peptide encoding the simian virus 40 NLS. This effect is abolished by substituting any two of the four basic residues in this NLS. Overexpression of a modified form of SRF in which these basic residues have been mutated confirms the absolute requirement for this sequence, and not the other basic amino acid sequences adjacent to it, in the nuclear localization of SRF. Since this NLS is in close proximity to potential phosphorylation sites for the cAMP-dependent protein kinase (A-kinase), we further investigated if A-kinase plays a role in the nuclear location of SRF. The nuclear transport of SRF proteins requires basal A-kinase activity, since inhibition of A-kinase by using either the specific inhibitory peptide PKIm or type II regulatory subunits (RII) completely prevents the nuclear localization of plasmid-expressed tagged SRF or an SRF-NLS-IgG conjugate. Direct phosphorylation of SRF by A-kinase can be discounted in this effect, since mutation of the putative phosphorylation sites in either the NLS peptide or the encoded full-length SRF protein had no effect on nuclear transport of the mutants. Finally, in support of an implication of A-kinase-dependent phosphorylation in a more general mechanism affecting nuclear import, we show that the nuclear transport of a simian virus 40-NLS-conjugated IgG or purified cyclin A protein is also blocked by inhibition of A-kinase, even though neither contains any potential sites for phosphorylation by A-kinase or can be phosphorylated by A-kinase in vitro.     

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.