山西雏蝗属二新种：直翅目：网翅蝗科

本文记述山西省雁北地区雏蝗属Ｃｈｏｒｔｈｉｐｕｓ Ｆｉｅｂｅｒ１８５２二新种,即郑氏雏蝗Ｃｈｏｒｔｈｉｐｐｕｓ ｚｈｅｎｇｉ,ｓｐ．ｎｏｖ．和宽带雏蝗Ｃｈｏｒｔｈｉｐｐｕｓ ａｍｐｌｉｌｉｎｅａｔｕｓ,ｓｐ．ｎｏｖ。模式标本保存在山西省农牧厅植保植检总结。     

简便、快速提取高质量的RNA分子

MethodsforHandy,RapidIsolationofHighQualityRNAbyGuanadiumThioeyauateDuJianYuanYanhuaMaShenglinDongZhiwei(BeijingInstituteforCancerResearchBeijing100034)硫氰胍是一种有效的蛋白变性剂。早在1979年,Chirgwin等就利用氯化铯／硫氰胍超离心技术成功地从RNA酶富集的胰脏组织中提取出未降解的RNA分子[2],从而使它成为抑制RNA酶的首选药物并得到广泛使用,但受到超速离心设备的限制。1983年,Cathala报道了氯化锂／硫氰胍RNA提取法[1]。该方法操作简便,获得的RNA质量很高,但所需时间较长。为了能在短时间内更快…     

Developmental regulation of alpha beta T cell antigen receptor expression results from differential stability of nascent TCR alpha proteins within the endoplasmic reticulum of immature and mature T cells.

The alpha beta T cell antigen receptor (TCR) that is expressed on most T lymphocytes is a multisubunit transmembrane complex composed of at least six different proteins (alpha, beta, gamma, delta, epsilon and zeta) that are assembled in the endoplasmic reticulum (ER) and then transported to the plasma membrane. Expression of the TCR complex is quantitatively regulated during T cell development, with immature CD4+CD8+ thymocytes expressing only 10% of the number of surface alpha beta TCR complexes that are expressed on mature T cells. However, the molecular basis for low TCR expression in developing alpha beta T cells is unknown. In the present study we report the unexpected finding that assembly of nascent component chains into complete TCR alpha beta complexes is severely impaired in immature CD4+CD8+ thymocytes relative to their mature T cell progeny. In particular, the initial association of TCR alpha with TCR beta proteins, which occurs relatively efficiently in mature T cells, is markedly inefficient in immature CD4+CD8+ thymocytes, even for a matched pair of transgenic TCR alpha and TCR beta proteins. Inefficient formation of TCR alpha beta heterodimers in immature CD4+CD8+ thymocytes was found to result from the unique instability of nascent TCR alpha proteins within the ER of immature CD4+CD8+ thymocytes, with nascent TCR alpha proteins having a median survival time of only 15 min in CD4+CD8+ thymocytes, but > 75 min in mature T cells. Thus, these data demonstrate that stability of TCR alpha proteins within the ER is developmentally regulated and provide a molecular basis for quantitative differences in alpha beta TCR expression on immature and mature T cells. In addition, these results provide the first example of a receptor complex whose expression is quantitatively regulated during development by post-translational limitations on receptor assembly.     

Analysis of the distribution and phosphorylation state of ZO-1 in MDCK and nonepithelial cells

We have examined the distribution and extent of phosphorylation of the tight junction-associated protein ZO-1 in the epithelial MDCK cell line, and in three cell types that do not form tight junctions: S180 (sarcoma) cells, S180 cells transfected with E-cadherin (S180L), and primary cultures of astrocytes. In shortterm calcium chelation experiments on MDCK cells, removal of extracellular calcium caused cells to pull apart. However, ZO-1 remained concentrated at the plasma membrane and no change in ZO-1 phosphorylation was observed. Maintenance of MDCK cells in low calcium medium, conditions where no tight junctions are found, resulted in altered ZO-1 distribution and lower total phosphorylation of the protein. In S180 cells, ZO-1 was diffusely distributed along the entire cell surface, with concentration of the antigen in motile regions of the cell. Cell-cell contact was not a prerequisite for ZO-1 localization at the plasma membrane in this cell type, and the phosphate content of ZO-1 was found to be lower in S180 cells relative to MDCK cells. Expression of Ecadherin in S180L cells did not alter either the distribution or phosphorylation of ZO-1. In contrast to S180 cells, ZO-1 in primary cultures of astrocytes was concentrated at sites of cell-cell contact, and the phosphorylation state was the same as that in control MDCK cells. Comparison of one-dimensional proteolytic digests of ³²P-labeled ZO-1 revealed the phosphorylation of two peptides in control MDCK cells that was absent in both MDCK cells grown in low calcium and in S180 cells.We would like to thank Cheryl Richards for her help with the cell culture and immunohistochemistry; David Begg, Gary Firestone, Vik Maraj, Manijeh Pasdar and Colin Rasmussen for helpful discussions; Jaclyn Peebles and Greg Morrison for help with graphics and photography; and Grace Martin and Bob Campenot for rat tail collagen. We are grateful to all the members of our laboratories for their friendship, advice and support. This work was supported by an Establishment Award to B.R.S. from the Alberta Heritage Foundation for Medical Research and grants to B.R.S. from the Kidney Foundation of Canada and the Medical Research Council of Canada. A.H. is funded by a Studentship from the AHFMR. K.L.S. was supported by a grant from the National Institutes of Health (DK-42799) to Gary L. Firestone. B.R.S. is a Medical Research Council of Canada and AHFMR Scholar.     

α2-Adrenoceptor-Mediated Inhibition of Electrically Evoked [3H]Noradrenaline Release from Chick Sympathetic Neurons: Role of Cyclic AMP

Abstract: This study explores the role of cyclic AMP in electrically evoked [³H]noradrenaline release and in the α₂-adrenergic modulation of this release in chick sympathetic neurons. Along with an increase in stimulation-evoked tritium overflow, applications of forskolin enhanced the formation of intracellular cyclic AMP. Both effects of forskolin were potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. The forskolin-induced increase in overflow was abolished by the Rp-diastereomer of cyclic AMP-thioate, an antagonist at cyclic AMP-dependent protein kinases, and 1,9-dideoxy-forskolin, an inactive analogue at adenylyl cyclase, had no effect on the evoked overflow. A 24-h pretreatment with either cholera toxin or forskolin reduced the subsequent forskolin-induced accumulation of cyclic AMP and inhibited the stimulation-evoked release. Basal cyclic AMP production, however, remained unaltered after forskolin treatment and was enhanced after 24 h of cholera toxin exposure. The α₂-adrenergic agonist bromoxidine did not affect the formation of cyclic AMP stimulated by forskolin but reduced electrically evoked release. However, effects of bromoxidine on ³H overflow were attenuated by forskolin as well as by 8-bromo-cyclic AMP. Effects of bromoxidine on [³H]noradrenaline release were paralleled by an inhibition of voltage-activated Ca²⁺ currents, primarily through a delayed time course of current activation. This effect was abolished when either forskolin or 8-bromo-cyclic AMP was included in the pipette solution. Both substances, however, failed to affect Ca²⁺ currents in the absence of bromoxidine. These results suggest that the signaling cascade of the α₂-adrenergic inhibition of noradrenaline release involves voltage-activated Ca²⁺ channels but not cyclic AMP. Elevated levels of cyclic AMP, however, antagonize this α₂-adrenergic reduction, apparently through a disinhibition of Ca²⁺ channels.     

Polygalacturonase-inhibiting protein accumulates in Phaseolus vulgaris L. in response to wounding, elicitors and fungal infection

Polygalacturonase-inhibiting protein (PGIP) is a cell wall-associated protein that specifically binds to and inhibits the activity of fungal endopolygalacturonases. The Phaseolus vulgaris gene encoding PGIP has been cloned and characterized. Using a fragment of the cloned pgip gene as a probe in Northern blot experiments, it is demonstrated that the pgip mRNA accumulates in suspension-cultured bean cells following addition of elicitor-active oligogalacturonides or fungal glucan to the medium. Rabbit polyclonal antibodies specific for PGIP were generated against a synthetic peptide designed from the N-terminal region of PGIP; the antigenicity of the peptide was enhanced by coupling to KLH. Using the antibodies and the cloned pgip gene fragment as probes in Western and Northern blot experiments, respectively, it is shown that the levels of PGIP and its mRNA are increased in P. vulgaris hypocotyls in response to wounding or treatment with salicylic acid. Using gold-labeled goat-anti-rabbit secondary antibodies in EM studies, it has also been demonstrated that, in bean hypocotyls infected with Colletotrichum lindemuthianum, the level of PGIP preferentially increases in those cells immediately surrounding the infection site. The data support the hypothesis that synthesis of PGIP constitutes an active defense mechanism of plants that is elicited by signal molecules known to induce plant defense genes.     

Comparative analysis of multiple protein-sequence alignment methods [published erratum appears in Mol Biol Evol 1994 Sep;11(5):811]

We have analyzed a total of 12 different global and local multiple protein-sequence alignment methods. The purpose of this study is to evaluate each method's ability to correctly identify the ordered series of motifs found among all members of a given protein family. Four phylogenetically distributed sets of sequences from the hemoglobin, kinase, aspartic acid protease, and ribonuclease H protein families were used to test the methods. The performance of all 12 methods was affected by (1) the number of sequences in the test sets, (2) the degree of similarity among the sequences, and (3) the number of indels required to produce a multiple alignment. Global methods generally performed better than local methods in the detection of motif patterns.      

An insertion element of the extremely thermophilic archaeon Sulfolobus solfataricus transposes into the endogenous β-galactosidase gene

Three phenotypically stable mutants of the extremely thermophilic archaeon Sulfolobus solfataricus have been isolated by screening for β-galactosidase negative colonies on plates with X-Gal (5-bromo-4-chloro-3-indolyl-(3-d-galactopyranoside). From one of these mutants an insertion element, designated ISC1217, was isolated and characterized. Sequence analysis of ISC1217 and of the regions adjacent to the insertion site in the β-galactosidase gene revealed features typical of a transposable element: ISC1217 contained terminal inverted repeats and was flanked by a direct repeat of 6 bp. The 1147 by sequence contained an open reading frame encoding a putative protein of 354 amino acid residues and, overlapping this, two smaller open reading frames on the opposite strand. There were approximately 8 copies of the insertion element in the S. solfataricus genome. ISC1217 did not cross-hybridize with DNA of other Sulfolobus species. All three independently isolated β-galactosidase mutants of S. solfataricus arose by transposition of ISC1217 or a related element.