采前与采后处理结合控制柿子贮藏过程中链格孢菌(Alternaria alternata)引起的黑斑病的研究

由链格孢菌引起的黑斑病是导致以色列柿子(Diospyros kaki cv.Triumph)贮藏过程中果实品质下降、贮期缩短的主要因素。其病原真菌在采收前的果园中即开始侵染果实,但一直处于休眠状态。采收后,在0℃贮藏环境中病原菌开始繁殖,当贮藏2～3个月后,柿果表面出现黑斑症状。商业上采用二氯异氰尿酸钠片剂溶解后生成500 mg.L-1的氯水浸果,可在2个月的贮期内有效控制黑斑病的发生。然而,当贮期超过2个半月后,柿子果实的腐烂率则不断增加。在柿子采后出现黑斑症状之前病原真菌较长的潜伏期内,采前与采后阶段可采取一系列的综合技术措施,并与商业氯水浸果处理相结合来提高对贮藏柿果黑斑病的防控效果。采前处理包括柿子坐果30 d后,以1-(2-氯-4-吡啶)-3-苯基脲(CPPU)处理或采收前14 d以治疗性杀菌剂多抗霉素(polyoxin B)进行喷果处理。试验结果表明,与采后单独使用氯水浸果处理相比,将CPPU或polyoxin B处理与采后商业处理相结合,可使柿果黑斑浸染面积分别减小3%和60%;采收后贮藏期间二氯异氰尿酸钠喷雾处理或采后立即用二氯异氰尿酸钠喷果处理与采后商业氯水处理相结合比单独使用氯水处理可分别提高柿子好果率2%和10%。研究结果表明,对于具有较长潜伏侵染方式的采后病原菌来说,可应用采前和采后处理相结合的方法来提高果实的贮藏品质及减轻采后病害的发生。     

Hsp90 potentiates the rapid evolution of new traits: drug resistance in diverse fungi

Hsp90 is a molecular chaperone for many signal transducers and may influence evolution by releasing previously silent genetic variation in response to environmental change. In fungi separated by approximately 800 million years of evolution, Hsp90 potentiated the evolution of drug resistance in a different way, by enabling new mutations to have immediate phenotypic consequences. Resistance was abrogated by Hsp90 inhibitors and by febrile temperatures, suggesting new therapeutic strategies and a clinical benefit of fever. During selection in a human host, drug resistance that was initially Hsp90-dependent evolved toward independence. Thus, Hsp90 can act in diverse ways to couple environmental contingency to the emergence and fixation of new traits.     

Peatland Interstitial Water Chemistry in Relation to that of Surface Pools along a Peatland Mineral Gradient

The elemental (including silica (Si), calcium (Ca), magnesium (Mg), manganese (Mn) and iron (Fe)) and nutrient composition of peatland surface pools and concentrations of Ca, Mg, Mn, and Fein peat interstitial waters and surface peat concentrations of oxides of Mn and Fe were determined for 15 peatlands sampled along a mineral gradient. Surface pool concentrations of Si wereca. ten fold less in surface pools of mineral-poor peatlands thanin the mineral rich, supporting the use of this element as an indicator of minerotrophic influence in peatlands. Principle component analysis of surface pool water chemistry parametersdifferentiated mineral-poor and moderately-poor peatlands frommineral-rich peatlands based on the concentrations of Ca, Mgand alkalinity of pools. Several lines of evidence indicated that peatland interstitial waters were important contributors to peatland alkalinity and included; (1) maximum interstitial water concentrations of Ca and Mg correlating with overlying surface pool alkalinity, (2) a negative correlation between interstitial water Ca:Mg ratios and surface pool concentrationsof Si and (3) Ca:Mg ratios of moderately-poor to mineral-poorpeatland interstitial waters approaching the Ca:Mg ratio of rainwater rather than those of bedrock. Interstitial water concentrations of dissolved Mn and Fe correlated with amountsof reducible Fe and Mn (oxides of Fe and Mn) recovered from thepeat/water interface indicating that groundwater inputs areimportant sources of these two elements to fens. As a consequence, for peatlands that are not truly ombrotrophic,groundwater inputs of Mn and Fe may interfere with interpretingpeat metal profiles thought to be due to anthropogenic inputs alone.     

Successful treatment of acute respiratory distress syndrome in 2 dogs

Acute respiratory distress syndrome (ARDS) was diagnosed in 2 dogs with acute dyspnea. Short-term positive pressure ventilation and intense critical and nursing care were provided. Both dogs improved and were discharged. Few reports describe successful recovery from ARDS. Due to advances in positive pressure ventilation and improvement in the supportive care of critically ill veterinary patients, the prognosis for ARDS may improve.     

Antiproliferative activity of Saponaria vaccaria constituents and related compounds

Total methanolic extracts of Saponaria vaccaria seed derived from several varieties, as well as various purified components obtained through successive chromatographic separations of total extracts were evaluated for their growth inhibitory activity in WiDr (colon), MDA-MB-231 (breast), NCI-417 (lung) and PC-3 (prostate) human cancer cells as well as the non-tumorigenic fibroblast BJ (CRL-2522) cell line using MTT colorimetric assay. Purified bisdesmosidic saponins segetoside H and I were further examined using microscopy and apoptosis assays. Bisdesmosidic saponins exhibited dose-dependent growth inhibitory and selective apoptosis-inducing activity. Growth inhibitory effects were particularly strong in a breast (MDA-MB-231) and a prostate (PC-3) cancer cell line. Total extracts exhibited a different preference being most active against a colon cancer cell line (WiDr). In a comparison of varieties, all of the total seed extracts exhibited similar dose-dependent activities, but with some variation in potency. Monodesmosidic saponins vaccarosides A and B, phenolic vaccarin, and cyclopeptide segetalin A, co-occurring seed substituents, did not exhibit activity. The non-tumorigenic fibroblast cell line BJ (CRL 2522) was growth inhibited but did not undergo apoptosis when treated with bisdesmosidic saponins at low micromolar concentrations. Saponin-rich extracts from Kochia scoparia seed and Chenopodium quinoa were also evaluated alongside Saponaria saponins but did not exhibit activity. Closely related Quillaja saponins exhibited activity but were less potent.     

Beneficial cross-protection of allergen-specific immunotherapy on airway eosinophilia using unrelated or a partial repertoire of allergen(s) implicated in experimental feline asthma

The study hypothesis was that in experimentally asthmatic cats rush immunotherapy (RIT) using allergens not completely matched with sensitizing allergen(s) would at least partially attenuate the asthmatic phenotype and modulate the aberrant immune response. In phase I, cats sensitized to Bermuda grass allergen (BGA), house dust mite allergen (HDMA) or placebo received BGA RIT. In phase II, cats dually sensitized to BGA and HDMA received RIT using BGA, HDMA or placebo. Efficacy of RIT was assessed using percentage bronchoalveolar lavage fluid (BALF) eosinophils. Additionally, a variety of immunologic assays were performed. Eosinophilic airway inflammation significantly decreased over time in asthmatic cats given RIT using sensitizing allergen or unrelated allergen (P<0.001). In dually sensitized cats, single allergen RIT but not placebo reduced airway eosinophilia (P=0.038). Differences in allergen-specific lymphocyte proliferation, in the number of IL-10 producing cells and in the percentage T regulatory cells were detected between asthmatic cats getting RIT and controls. Cross-protection manifested by reduced airway eosinophilia was noted in cats treated with RIT allergens which did not completely match allergen used in asthma induction. However, the mechanism of immunologic tolerance may differ when improperly matched allergens to the sensitizing allergens are used in RIT.