香蕉束顶病和花叶心腐病的快速测定技术研究

种植无病蕉苗是防治香蕉束顶病和花叶心腐病的根本措施。筛选无病蕉苗的快速测定技术。除可引用2,3,5-氯化三苯基四(氨)唑浸渍徒手切片;在36℃条件下。24小时后:束顶病株叶脉切片的维管束呈现红色,其它组织为红褐色;花叶心腐病株叶脉切片(含维管束)全部呈现黑褐色;而健株叶脉切片由原绿色变成红色,最后褪成无色。此外。也可取叶片主脉的徒手切片,用1％曙红B水溶液染色。健株切片呈桔红色,病株切片呈砖红色,通过镜检:束顶病株叶片切片的表皮下,可观察到围绕在维管束周围成堆的分布有畸形叶绿体细胞团;花叶心腐病的畸形叶绿体细胞团,多分布在薄壁细胞中,且多散生;而健株的切片没有发现这种畸形的叶绿体细胞团,两种方法同样可靠。     

桥本甲状腺炎患者外周血miR-142-3p、miR-125a-5p水平与甲状腺功能和Th1/Th2及Th17/Treg细胞平衡的关系

摘要 目的：探讨桥本甲状腺炎（HT）患者外周血微小核糖核酸（miRNA）-142-3p、miR-125a-5p水平与甲状腺功能和辅助性T细胞（Th）1/Th2及Th17/调节性T细胞（Treg）细胞平衡的关系。方法：选取2020年1月～2023年8月我院收治的HT患者90例作为HT组和同时间段90名体检健康者作为对照组,根据甲状腺功能减低程度将HT患者分为甲状腺功能正常组（26例）、亚临床甲状腺功能减退组（31例）和临床甲状腺功能减退组（33例）。采用实时荧光定量聚合酶链式反应检测外周血miR-142-3p、miR-125a-5p水平,酶联免疫吸附法检测甲状腺功能指标[甲状腺球蛋白抗体（TgAb）、甲状腺过氧化物酶抗体（TPOAb）、促甲状腺激素（TSH）、游离三碘甲状腺原氨酸（FT₃）、游离甲状腺素（FT₄）],流式细胞术检测外周血Th1、Th2、Th17、Treg细胞比例,并计算Th1/Th2及Th17/Treg比值。通过Pearson/Spearman相关性分析HT患者外周血miR-142-3p、miR-125a-5p与甲状腺功能、Th1、Th2、Th17、Treg的相关性。结果：HT组外周血miR-142-3p、miR-125a-5p、TgAb、TPOAb、TSH、Th1、Th17、Th1/Th2、Th17/Treg比值高于对照组,FT₃、FT₄、Th2、Treg比例低于对照组（P＜0.05）。甲状腺功能正常组、亚临床甲状腺功能减退组、临床甲状腺功能减退组外周血miR-142-3p、miR-125a-5p、TgAb、TPOAb、TSH、Th1、Th17、Th1/Th2、Th17/Treg比值依次升高,FT₃、FT₄、Th2、Treg比例依次降低（P＜0.05）。Pearson/Spearman相关性分析显示,HT患者外周血miR-142-3p、miR-125a-5p与TgAb、TPOAb、TSH、Th1、Th17、Th1/Th2、Th17/Treg呈正相关,与FT₃、FT₄、Th2、Treg呈负相关（P＜0.05）。结论：HT患者外周血miR-142-3p、miR-125a-5p水平升高,与甲状腺功能减退和Th1/Th2、Th17/Treg细胞失衡有关。     

TTC-脱氢酶还原法测定螺旋藻细胞活性的条件优化

为确定氯化三苯基四氮唑(TTC)-脱氢酶还原法测定螺旋藻细胞活性的最优条件,首先通过单因素实验对影响藻细胞活性测定的TTC质量分数、缓冲液pH、提取剂（乙醇）质量分数、培养时间、培养温度进行分析,选定各因素的变化范围,再利用正交试验设计方法,在藻细胞活性测定的最适培养温度下,对TTC质量分数、缓冲液pH、提取剂质量分数、培养时间进行3水平优化试验。最后确定优化的TTC 脱氢酶还原法测定螺旋藻细胞活性的条件为TTC质量分数0.1%、缓冲液pH 8.0~8.5、乙醇质量分数60%、培养时间5 h、培养温度35 ℃。在此条件下所测藻细胞活性最高,为螺旋藻细胞活性的评价提供了一定参考。     

Effect of the recC gene in Escherichia coli on frequencies of ultraviolet-induced mutants

UV induction of Lac^? mutations was compared with UV induction of Mal⁺ mutations in E. coli B/r strains differing in the recC gene. The frequency of Lac^? mutants per survivor induced by the same dose was not significantly affected by the recC gene but the percentage of pure rather than sectored Lac^? colonies was greater when the recC gene was present. On the other hand, as reported previously, frequencies of Mal⁺ mutants induced by the same UV dose were lower when the strain was recC. The reduction factor was the same as for spontaneous Mal⁺ mutants. The difference in the effect of the recC gene on the yields of Lac^? and Mal⁺ mutants can be explained by taking into account the influence of lethal sectoring, which introduces an artifact when mutants arising in the recC strain are scored selectively as in the case for Mal⁺ mutants, but not when the scoring is non-selective as for Lac^? mutants. Lethal sectoring as indicated by a discrepancy between total cell counts and numbers of colony-formers, was observed for the recC strain growing in liquid minimal medium corresponding to the agar medium used to score Mal⁺ mutants but was not observed for the rec⁺ strain. Both strains showed lethal sectoring in the liquid medium corresponding to the agar medium to score Lac^? mutants. The hypothesis concerning the role of lethal sectoring in the selective scoring of mutants arising in a recC background is supported by evidence concerning the UV induction of mutants in a polA1 background. Like the recC gene, the polA1 gene did not affect yields of Lac^? mutants. However, unlike the recC gene, the polA1 gene has previously been shown not to influence UV yields of prototrophic mutations (scored selectively) and not to cause lethal sectoring except under irrelevant conditions.     

Comparison of the Neutral Red and Methylene Blue Assays to Study Cell Growth in Culture

The neutral red and methylene blue in vitro cytotoxicity assays were compared under a variety of conditions using normal human ovarian epithelial cells to determine whether either assay is superior for studying cell growth. The results were standardized against a DNA spectrofluorometric assay. Although the assays were equivalent in reflecting cell number, each has specific advantages: while neutral red discriminates between viable and dead cells, the methylene blue assay is more sensitive and easier to perform.     

Comparison of MTT and ATP-based assays for the measurement of viable cell number

Cell viability assays are widely used to assess the effect of chemotherapeutic drugs and other agents on cell lines and have shown promise for the prediction of tumour chemosensitivity. In this study we have compared two viability assays using Daudi and CCRF-CEM cell lines over a range of 1500–100,000 cells/well of a microplate. The ATP assay was able to detect the lower limit of 1563 cells/well with luminescence values at least 100× background readings, while the MTT assay could not detect less than 25,000 cells/well above background readings. The ATP assay also showed better reproducibility and sensitivity when cells were grown in microtitre plates over several days, and is particularly useful for the measurement of viability with low cell numbers.     

Heat shock proteins and thermotolerance in a cultured cell line from the Mediterranean fruit fly, Ceratitis capitata.

Heat shock proteins (hsps) were identified in a cell line from the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae) exposed to elevated temperatures. Cells produced three hsps (Mr 87,000, 69,000, and 34,000) in response to a temperature shift from 26 degrees C to 37 degrees C (30-60 min) with a concomitant decrease in synthesis of most other cellular proteins. Synthesis of low Mr hsps was not evident. The heat shock response is triggered within 30 min at temperatures from 33 degrees C to 41 degrees C. At temperatures greater than 41 degrees C protein synthesis was shut down. Within 2-3 h after return to 26 degrees C, synthesis of proteins repressed at the higher temperatures resumed production while the major hsps disappear. Heat shock proteins were not produced in the presence of actinomycin D. Evaluations on the role of hsps in conferring thermotolerance to the cells showed an increase in cell viability in heat-shocked cells over non-heat-shocked cells (after 3 and 10 days) when subsequently placed at 45 degrees C for 1 h, a normally lethal temperature. Heat shock alone had little effect on subsequent cell viability or growth at 26 degrees C. These results suggest that hsps produced by these cells may aid in the maintenance of cell integrity and thus play a transitory role in thermotolerance.     

Response of Eucalyptus camaldulensis Dehnh., E. globulus Labill. ssp. globulus and E. grandis W.Hill to excess boron and sodium chloride

In a sand culture experiment we investigated the effects of boron (0.01, 0.19, 0.46 and 0.93 mol m⁻³ B, as H₃BO₃), sodium chloride (0, 100 and 200 mol m⁻³ NaCl) and combined B and NaCl, over 36 days, on growth, water use and foliar ion concentrations of nine week-old seedlings of three fast-growing, commercial eucalypts ( Eucalyptus camaldulensis Dehnh. , E. globulus Labill. ssp. globulus and E. grandis W.Hill.). Shoot dry weight was significantly reduced by high concentrations of NaCl (p < 0.001) and by B and NaCl in combination (p ≤ 0.05) but not by B alone. Root dry weight was significantly reduced by both NaCl (p < 0.001) and B (p < 0.001), but not by combined B and NaCl. Foliar B concentrations increased with higher concentrations of applied B and decreased with higher NaCl concentrations. Foliar Na concentrations were greater with higher NaCl concentrations, whereas B application had no significant effect on foliar Na concentrations. All three species accumulated relatively high B concentrations in leaves. Severe boron toxicity symptoms (BTS) were apparent only when leaf B concentrations exceeded 50 mol x 10⁻⁶ g⁻¹, but even at these high concentrations plant growth was only slightly reduced. E. camaldulensis showed least development of BTS, the lowest leaf B concentrations and least reduction in height growth due to B and NaCl. The results suggest that there was a correlation between both B tolerance and B accumulation in leaves and between tolerance to B and NaCl. This revised version was published online in June 2006 with corrections to the Cover Date.     

Functional copper requirement for catechol oxidase activity in plantation Eucalyptus species

Copper (Cu) deficiency in eucalypts is associated with tree deformation and reduced wood production from plantations. Presently, diagnosis of the early stages of Cu deficiency is unreliable as critical tissue Cu concentrations for tree growth have not been defined. Since wood quality is usually impaired in advance of tree growth, a biochemical test for Cu deficiency was sought for three Eucalyptus species commonly used in plantation forestry (E. globulus Labill., E. grandis Hill ex Maiden and E. urophylla Blake). Foliar Cu requirements for catechol oxidase activity were determined in a glasshouse sand culture study with 10 rates of Cu supply (0, 10^-15, 10^-14, 10^-13, 10^-12, 10^-11, 10^-10, 10^-9, 10^-7 and 10^-5 M). In contrast to shoot dry weight, which only responded to Cu supply in E. urophylla, foliar Cu concentration and catechol oxidase activity, in 140-day-old seedlings, increased with the addition of Cu in all species. Stem lignification also responded to Cu supply in parallel to the activity of catechol oxidase. Functional Cu requirements of 2.4, 2.1 and 2.6 mg kg^-1 dry weight for catechol oxidase activity in E. globulus, E. grandis and E. urophylla, respectively, were derived from statistical models fitted to the relationship between catechol oxidase activity and Cu concentrations in recently matured leaves.