猫尾核头部前区对三叉神经尾端脊束核的抑制作用及其方式

在清醒麻痹状态下的55只猫上,观察了电刺激尾核头部前区(Cd)对三叉神经尾端脊束核(cST)中了齿槽神经(AI)伤害性刺激所诱发的放电的影响。刺激 Cd 可以抑制大多数 cST 神经元的伤害性反应,抑制持续约100—500ms。抑制时程可为静脉注射戊巴比妥钠和安定而延长,注射印防己毒素可使其缩短。马钱子素使抑制时程稍有延长。这些结果提示,Cd 对 cST神经元的抑制作用是通过突触前抑制的方式实现的。     

人工补充寄主卵对松林内卵蜂种群消长的影响

在不同生境的松林中,人工补充寄主卵都能提高寄生效果。但林地生境不同,寄生率有明显差异。在松阔混交林中补充寄主,其寄生率比对照提高5.5—16.2倍。植被稀疏的纯松林效果较差,补充的寄生率比对照提高3.0倍。 卵蜂种群消长随季节温度而变化,全年以5月中旬至6月下旬和9月中旬至10月中旬为两个寄生高峰。卵蜂种群与松毛虫种群的消长存在较明显的相依关系,卵蜂种群随着松毛虫种群的消长而消长。施药对卵蜂种群有较大影响,施药区比对照区的寄生率约降低一倍。在混交林中填充寄主卵,能促进卵蜂种群世代延续。在逐步改善林地生境的基础上,利用人工补充寄主,可以代替人工繁蜂放蜂。     

Molecular cloning of rat intestinal mucin. Lack of conservation between mammalian species

We have prepared antisera to deglycosylated rat intestinal mucin and used it to obtain immunoreactive clones from a rat jejunum cDNA library. Four of these clones were sequenced, and all were found to be partial cDNAs that contained 18-base pair tandem repeats characteristic of a mucin. These cDNAs encoded a repetitive peptide with a consensus sequence of TTTPDV. Thus, they bear little resemblance to either of the two human intestinal mucin cDNAs isolated previously (Gum, J. R., Byrd, J. C., Hicks, J. W., Toribara, N. W., Lamport, D. T. A., and Kim, Y. S. (1989) J. Biol. Chem. 264, 6480-6487 and Gum, J. R., Hicks, J. W., Swallow, D. M., Lagace, R. E., Byrd, J. C., Lamport, D. T. A., Siddiki, B., and Kim, Y. S. (1990) Biochem. Biophys. Res. Commun. 171, 407-415). One of these rat mucin clones, designated RMUC 176, was chosen for further analysis. This clone recognized a band of approximately 9 kilobases when used to probe RNA blots. A strong hybridization band was present using rat small intestine and colon RNA but was not detectable when RNA isolated from heart, liver, or kidney was tested. The RMUC 176 clone and the two previously isolated human intestinal mucin cDNA clones were used to probe blots prepared from BamHI-digested DNA of various species. Here, the human probes detected fragments present only in human and chimpanzee DNA, whereas the RMUC 176 clone recognized fragments only in rat and mouse DNA. Thus, the repetitive portions of intestinal mucin genes are apparently not well conserved between phylogenetically distant species.     

Dosage of the smallest chromosome affects both the yeast-hyphal transition and the white-opaque transition of Candida albicans WO-1.

The WO-1 strain of Candida albicans is capable of alternating between two highly distinct yeast cell types termed white and opaque (E. H. A. Rikkerrink, B. B. Magee, and P. T. Magee, J. Bacteriol. 170:895-899, 1988; B. Slutsky, M. Staebell, J. Anderson, L. Risen, M. Pfaller, and D. R. Soll, J. Bacteriol. 169:189-197, 1987). We have isolated WO-1 mutants that show a marked deficiency at being able to switch from the white form to the opaque form under conditions normally favorable for this transition. Pulsed-field electrophoresis demonstrated that one of the initial two spontaneous nonswitching mutants lacked the smallest chromosome that is normally present in WO-1. The availability of a WO-1 derivative whose only functional ADE2 gene is located on this small chromosome made possible, through the induction of chromosome nondisjunction, the isolation of numerous new mutants missing this chromosome as well as mutants containing two copies of the chromosome. Mutants missing the smallest chromosome showed a greatly diminished ability to produce opaque sectors and to produce germ tubes in the presence of human serum. Mutants containing two copies of the small chromosome showed an increased ability to produce germ tubes. These results indicate that this small chromosome carries one or more genes involved in both the white-opaque switch and the yeast-hyphal switch.     

中国吻额蛛属一新种（蜘蛛目：皿蛛科：微蛛亚科）

本文描述了作者1986年采自湖北省神农架林区的吻额蛛属Aprifrontalia一新种:膨大吻额蛛,新种Aprifrontalia afflata sp.nov.。目前,除本新种外,世界仅报道过1种:Aprifrontalia mascula,本新种雄蛛最显著的特征是:其额向前突呈吻状,触肢胫节前端甚膨大。外雌器形成一斜向下方的突起。模式标本保存于白求恩医科大学生物教研室。     

Differential localizations of and requirements for the two Drosophila ninaC kinase/myosins in photoreceptor cells

The ninaC gene encodes two retinal specific proteins (p132 and p174) consisting of a protein kinase domain joined to a domain homologous to the head region of the myosin heavy chain. The putative myosin domain of p174 is linked at the COOH-terminus to a tail which has some similarities to myosin-I tails. In the current report, we demonstrate that the ninaC mutation results in light- and age-dependent retinal degeneration. We also show that ninaC flies display an electrophysiological phenotype before any discernible retinal degeneration indicating that the electrophysiological defect is the primary effect of the mutation. This suggests that ninaC has a role in phototransduction and that the retinal degeneration is a secondary effect resulting from the defect in phototransduction. To examine the requirements for the individual ninaC isoforms, mutant alleles were generated which express only p132 or p174. Elimination of p174 resulted in a ninaC phenotype as strong as the null allele; however, elimination of p132 had little if any effect. As a first step in investigating the basis for the difference in requirements for p174 and p132 we performed immuno-localization at the electron microscopic level and found that the two isoforms display different subcellular distributions in the photoreceptor cells. The p132 protein is restricted primarily to the cytoplasm and p174 to the rhabdomeres, the microvillar structure which is the site of action of many of the steps in phototransduction. This suggests that the p174 myosin-I type tail is the domain responsible for association with the rhabdomeres and that the substrate for the p174 putative kinase may be a rhabdomeric protein important in photo-transduction.     

The human MUC2 intestinal mucin has cysteine-rich subdomains located both upstream and downstream of its central repetitive region.

The human MUC2 mucin is a large secretory glycoconjugate that coats the epithelia of the intestines, airways, and other mucus membrane-containing organs. Previous work has shown that this mucin contains an extended tandem repeat-containing domain rich in Thr and Pro. In the present work we describe two additional regions of this mucin located both upstream and downstream of the tandem repeat array. The carboxyl-terminal domain contains 984 residues and can be divided into mucin-like (139 residues) and cysteine-rich (845 residues) subdomains. This latter subdomain exhibits varying degrees of sequence similarity to a wide range of mucins and mucin-like proteins including those isolated from rats, pigs, cows, and frogs. We also report here the sequence of 1270 residues lying immediately upstream of the tandem repeats. This region contains a repetitive, mucin-like subdomain and a second cysteine-rich stretch of more than 700 residues. Both cysteine-rich subdomains of this mucin have sequence similarity with von Willebrand factor, a serum protein that exists as a disulfide-linked polymer. This suggests that these cysteine-rich subdomains are important in the catenation of mucin monomers into oligomers, the structures that confer viscoelasticity upon mucus.     

Interactions between Pseudomonas aeruginosa and iodophor germicides in milking parlor udder wash water systems.

In a field study of 29 dairy farms, Pseudomonas aeruginosa was isolated more frequently (P = 0.05) from milking parlor udder wash water systems containing iodophor germicides than from those with no germicide. Most available iodine (AI2) concentrations were below the recommended level of 25 ppm (25 microgram/ml). Rubber and polyvinyl chloride hoses caused rapid decreases in the AI2 concentrations of 25 ppm iodophor solutions. AI2 dropped from 25 ppm to 6 ppm or less in 240 min for solutions contained in either polyvinyl chloride or rubber, compared with solutions in glass, which were unchanged in 240 min. Addition of inactivated iodophor solution to aqueous cultures resulted in significantly higher (P less than 0.05) numbers of P. aeruginosa at 10 and 24 h postinoculation. P. aeruginosa was grown in polyvinyl chloride tubing and exposed twice daily to 0, 10, or 25 ppm of AI2. None of the exposure concentrations eliminated the bacteria from the hoses, and bacterial numbers were not significantly different in hoses exposed to 0 and 10 ppm by the eighth treatment day. Bacteria taken from the water in these hoses were exposed to different concentrations of iodophor solution. Iodophor concentrations which will kill 50% of P. aeruginosa cultures previously exposed to 0, 10, and 25 ppm of AI2 were predicted to be 3.0, 11.8, and 20.8 ppm, respectively.     

Chromosomal rearrangements associated with morphological mutants provide a means for genetic variation of Candida albicans.

At frequencies as high as 1.4%, the pathogenic yeast Candida albicans spontaneously gave rise to morphological mutants exhibiting more than 20 different types of abnormal colonies; approximately two-thirds of the mutants were stable, while the other one-third were unstable and produced mixtures of different colonial forms at very high rates. Abnormal electrophoretic karyotypes were observed for all of the 14 mutants that were examined, indicating that they were associated with different types of single and multiple gross chromosomal rearrangements. Because C. albicans is asexual and does not go through a meiotic cycle, we suggest that the high frequency of chromosomal rearrangements provides a means for genetic variation in this organism.     

Molecular cloning of cDNAs derived from a novel human intestinal mucin gene

A human small intestinal lambda gt11 cDNA library was screened with antibodies to deglycosylated small intestinal mucin. Four partial cDNA clones were isolated that define a novel human mucin gene. These include two partial cDNA clones, SIB 124 and SIB 139, that contain 51 nucleotide tandem repeats which encode a seventeen amino acid repetitive peptide with a consensus sequence of HSTPSFTSSITTTETTS. SIB 139 hybridized to messages produced by small intestine, colon, colonic tumors and also by high mucin variant LS174T colon cancer cells. The gene from which cDNAs SIB 124 and SIB 139 are derived (proposed name MUC 3) maps to chromosome 7, distinct from other known human mucin genes.