Tautomerism of 4-hydroxy-2,5-dimethyl-3(2H)-furanone: evidence for its enantioselective biosynthesis

Chiral natural flavor compounds exhibit characteristic enantiomeric excesses due to stereoselective, enzymatically catalyzed reactions during biogenesis. Although the enzymatic formation of the strawberry key flavor compound 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF; Furaneol(R)) is anticipated, the naturally occurring compound is racemic. As racemization due to keto-enol-tautomerism of HDMF could account for this observation, HDMF was investigated by (1)H-NMR spectroscopy tracing the exchange of the proton bound to the furanone-ring at C2 with deuteron from the medium (D(2)O). In addition, the racemization rate of HDMF was directly determined by cyclodextrin-modified capillary electrophoresis of enantiomerically enriched HDMF stored at different pH values. Tautomerism and the racemization rate of HDMF was lowest at pH values between 4 and 5. However, tautomerism and thus racemization was catalyzed under stronger acidic conditions (pH 2) and especially at pH values greater than 7, the value published for plant cell cytosol. Approximately 50% of the protons at C2 were exchanged with deuteron within 1 h at pH 7.2. Therefore, in order to demonstrate the enzymatic formation of HDMF, incubation experiments with Zygosaccharomyces rouxii as well as strawberry protein extract were carried out under slightly acidic conditions (pH 5), the most suitable pH value for studies on the enantiomeric ratio of HDMF. In both experiments the formation of enantiomerically enriched HDMF could be demonstrated for the first time, whereas incubation experiments under neutral conditions resulted in the detection of racemic HDMF.     

基于方证相关探讨茵陈蒿汤调控库普弗细胞功能及MAPK通路抗肝纤维化的作用机制

目的：基于前期茵陈蒿汤类方抗肝硬化的方证病理基础结果,围绕“方-证相关”的学术内涵,提出了“方证相关时,方剂对机体基因的调控遵循‘无差错修复’原则”的假说;并探讨茵陈蒿汤对DMN诱导大鼠肝纤维化形成阶段肝组织库普弗细胞（Kupffer Cells,KCs）相关基因表达及对丝裂原活化蛋白激酶（MAPK）通路的影响。方法：采用wistar大鼠,于每周前3天连续腹腔注射0．5％二甲基亚硝胺（Dimethylnitrosamine,DMN）制备大鼠肝纤维化模型,2周末取模型组6只做动态观察。第3周初开始,在持续造模的同时给予茵陈蒿汤干预治疗到4周末,正常组与模型对照组给予等量生理盐水。4周末在3％戊巴比妥钠腹腔注射麻醉情况下,杀鼠取材,检测肝功能、肝组织病理、肝组织羟脯氨酸含量、胶原半定量,并采用基因芯片检测分析茵陈蒿汤对模型大鼠肝组织基因表达谱的影响。结果：与正常组比较,造模4周大鼠血清肝功能水平明显升高（P＜0．01）;病理观察肝组织炎细胞显著浸润,胶原显著沉积（P＜0．01）,肝组织白介素1（IL-1 b）、Cd68、肿瘤坏死因子受体超家族成员14（Tnfrsf14）、肿瘤坏死因子受体超家族成员9（Tnfrsf9）、TNF受体超家族成员6（Fas）、Cd14、结缔组织生长因子（Ctgf）、Ⅰ型胶原α2（Col1 a2）、胰岛素样生长因子结合蛋白（Igfals）、胰岛素样生长因子1（Igf1）、胰岛素样生长因子结合蛋白1（Igfbp1）、基质金属蛋白酶12（Mmp12）、基质金属蛋白酶2（Mmp2）、基质金属蛋白酶23（Mmp23）、趋化因子配体21（Ccl21）、蛋白激酶Cβ（Prkcb）基因表达明显上调,MAPK通路被激活。经2周治疗后茵陈蒿汤能显著降低DMN诱导的大鼠血清肝功能水平,抑制组织炎细胞的浸润与坏死,胶原沉积,并下调了肝组织IL-1 b、Cd68、Tnfrsf14、Tn-frsf9、Fas、Cd14、Ctgf、Col1 a2、Igfals、Igf1、Igfbp1、Mmp12、Mmp2、Mmp23、Ccl21、Prkcb 基因的表达,抑制了MAPK通路的活化。通过全基因芯片的分析,在茵陈蒿汤干预治疗后基因表达得到了不同程度的修复。结论：验证了“方证相关时,方剂对机体基因的调控遵循‘无差错修复’原则”的假说;茵陈蒿汤显著抑制DMN 诱导肝纤维化形成,其机制可能是调控了KCs,抑制相关炎症因子的释放,同时可能参与调控MAPK通路,从而达到抗肝纤维化的作用。     

不同温度条件下香水文心兰花香气的成分分析及感官评定

Flower aromatic components and their relative contents of Oncidium Sharry Baby ‘Sweet Fragrance ’ at full flowering stage under conditions of 10 ℃, 20 ℃ and 30 ℃ were analyzed by solid phase micro-extr...     

Conodont biostratigraphy of Tournaisian shallow-water carbonates in central Guangxi,South China

The conodont faunas of Tournaisian shallow-water carbonates from central Guangxi are described mainly for biostratigraphic purposes. A complete series of samples was collected from the Long’an and Du’an formations in the Long’an section. These formations are characterized by lime-mudstone, skeletal and peloidal wackestone, packstone and grainstone with typical shallow-water biota. Overall, these samples produced 809 identifiable Pl elements, belonging to 50 species in 11 genera, of which one species and one subspecies are new. The fauna enables the establishment of seven biozones (in ascending order): Polygnathus spicatus, Siphonodella homosimplex, S. sinensis, S. dasaibaensis, Polygnathus communis carina Acme, Gnathodus cuneiformis, and P. communis porcatus zones. Based on these new collections from central Guangxi and on data from the literature, a conflated Tournaisian conodont zonation is proposed for shallow-water successions in South China. Most of the conodont zones correlate well with their counterparts recognized in Western Europe, which may be of greater significance in stratigraphic correlation than previously thought.     

中国东北圆柏属新品种——直立型偃柏

发表了圆柏属一新品种,即直立型偃柏（Sabina chinensis（L.）Ant. var. sargentii ‘Electus’）。新品种为直立的灌木或小乔木;叶两型鳞叶交互对生或生于小枝顶部,针叶刺状轮生,紧贴枝上,具有强烈分枝的特点,枝条斜上。     

A multiplex PCR assay to distinguish among three sympatric marsupial taxa from Huon Peninsula, Papua New Guinea, using the mitochondrial control region

Matschie’s tree kangaroo (Dendrolagus matschiei) is an endangered arboreal macropodid marsupial that is difficult to locate in the wild. The Tree Kangaroo Conservation Program noninvasively collected D. matschiei faecal samples, but a high percentage of samples were misidentified and belonged to two terrestrial macropods, New Guinea pademelon (Thylogale browni) and small dorcopsis (Dorcopsulus vanheurni). We developed species-specific primers that produced a unique sized mitochondrial DNA control region gene product for each taxon and achieved an 89% correct assignment rate. The species-specific primers can increase the accuracy of D. matschiei density estimates and facilitate additional genetic analyses of wild D. matschiei.     

草莓高效离体叶片再生体系的建立

以草莓'明宝(Meiho)'和'红颊(Benihope)'的叶片为外植体,研究了不同基本培养基、暗培养时间、植物生长调节剂、叶龄、不同放置方式对其不定芽再生的影响.结果表明:各品种叶片不定芽离体再生的最佳条件不同.'明宝'叶片的最佳不定芽再生培养基为MS+2.5 mg/L TDZ+0.1 mg/L IBA+0.1 mg/L 2,4-D,叶片再生的最佳叶龄为30～40 d,再生率可达82.8%;'红颊'叶片的最佳不定芽再生培养基为MS+2.0 mg/L TDZ+0.1 mg/L IBA+0.1 mg/L 2,4-D,叶片再生的最佳叶龄在10～20 d,再生率可达79.8%.2个品种叶片暗培养14 d可以提高不定芽再生率;叶片正放比反放再生效果好;添加8 mg/L AgNO3和1 000 mg/L活性炭可有效提高再生率.     

Polyamines in normal and auxin-induced strawberry fruit development

The possible involvement of polyamines during strawberry ( Fragaria × ananassa Duch.) fruit development was investigated. Putrescine, spermidine, and spermine were identified in strawberry receptacles and achenes at all stages of development. Total (free) polyamine levels decreased from a maximum of 485 nmol g⁻¹ fresh weight at pollination to a minimum of 55 nmol g⁻¹ fresh weight in ripe receptacles. Total polyamine concentrations during corresponding stages of development were consistently higher in achenes than in receptacles, and ranged from 891 to 203 nmol g⁻¹ fresh weight. Removal of achenes from the surface of developing receptacles 10 days after pollination reduced receptacle growth, and re-initiation of growth by application of 1 m M α-naphtaleneacetic acid (α-NAA) was accompanied by a rapid increase in polyamine concentrations 24 h after treatment. Polyamine content per receptacle increased >3-fold in normally developing receptacles and in de-achened, auxin-treated receptacles 10 days after removal of achenes, but did not increase during this period in de-achened receptacles not treated with exogenous auxin. α-NAA increased growth and polyamine levels to a greater extent than the structurally related, but less effective auxin, β-NAA. Polyamine concentrations in receptacles with intact achenes remained similar to those of auxin depleted (de-achened) receptacles, implying that the concentration of these compounds may not be limiting following achene removal.     

Non-resident definitive host presence is sufficient to sustain avian schistosome populations

To control swimmer’s itch in northern Michigan inland lakes, USA, one species of bird, the common merganser (Mergus merganser), has been relocated from several lakes since 2015. Relocation efforts are driven by a desire to reduce the prevalence of the swimmer’s itch-causing parasite Trichobilharzia stagnicolae. The intention of this state-sponsored control effort was to interrupt the life cycle of T. stagnicolae and reduce parasite egg contribution into the environment from summer resident mergansers such that infections of the intermediate snail host Stagnicola emarginata declined. Reduced snail infection prevalence was expected to substantially reduce the abundance of the swimmer’s itch-causing cercarial stage of the parasite in water. With no official programme in place to assess the success of this relocation effort, we sought to study the effectiveness and impact of the removal of a single definitive host from a location with high definitive host and parasite diversity. This was assessed through a comprehensive, lake-wide monitoring study measuring longitudinal changes in the abundance of three species of avian schistosome cercariae in four inland Michigan lakes. Environmental measurements were also taken at these lakes to understand how they can affect swimmer’s itch incidence. This study demonstrates that the diversity of avian schistosomes at the study lakes would likely make targeting a single species of swimmer’s itch-causing parasite meaningless from a swimmer’s itch control perspective. Our data also suggest that removing the common merganser is not an effective control strategy for the T. stagnicolae parasite, likely due to contributions of the parasite made by non-resident birds, possibly migrants, in the autumn and spring. It appears likely that only minimal contact time between the definitive host and the lake ecosystem is required to contribute sufficient parasite numbers to maintain a thriving population of parasite species with high host specificity.     

Morphological and Phylogenetic Resolution of <i>Diplodia neojuniperi</i> Emerging <i>Diplodia</i> Top Dieback of <i>Pinus thunbergii</i> Parl. in China

In Bazhong City, Sichuan Province, China, top dieback symptoms were found on many pine trees (Pinus thunbergii Parl). The tips of old needles first turned grayish-green and then developed into brown bands in the field. Phylogenetic analysis of concatenated ITS and EF1-α indicated the pathogen of this dieback disease as Diplodia neojuniperi. Additionally, effects of temperature, pH and medium on the mycelial growth were also characterized. The most favorable temperature and pH level for mycelial growth are 25°C and 8, respectively. The optimal medium for mycelial growth is PDA medium. To our knowledge, this is the first report of D. neojuniperi causes Diplodia top dieback on Pinus thunbergii. Our results provide fundamental information for monitoring and preventing such disease in the future.