一种新型的DNA荧光染料-DAPI的光学特性及其应用

近年来,由于荧光显微镜的改进,荧光染料的不断增多以及免疫荧光技术的发展,荧光显微术已在细胞生物学的研究中广泛应用。荧光显微术用于研究细胞核和染色体已有较长的历史,不过目前除了哺乳类染色体分带荧光技术和孚尔根型荧光染色有所发展外,曾经使用过的一些核的荧光染色方法已应用不多。最近,一种新型的DNA荧光染     

N-（4-甲基-2-氨基苯并噻唑）α-氨基-α-（3-三氟甲基苯基）-0，0-二（2-烷氧基乙基）亚膦酸酯对小麦赤霉病原菌的抑制活性及作用机制的初步探究

实验室条件下采用生长速率法测定化合物N-(4-甲基-2-氨基苯并噻唑)α-氨基-α-(3-三氟甲基苯基)-O,O-二(2-烷氧基乙基)亚膦酸酯对小麦赤霉病原菌(Fusarium graminearum)的离体抑制效果,并初步研究了其抑制小麦赤霉病原菌作用机制.实验结果表明,该化合物对小麦赤霉病原菌的EC_(50)为46.05 μg/mL,当化合物浓度为50 μg/mL时,对该病原菌的抑制率就达到了60.5 %.以浓度为250 μg/mL的该供试化合物处理小麦赤霉病原菌菌丝24 h后,其细胞膜通透性增强,菌体内还原糖、几丁糖和可溶性蛋白含量及几丁质酶活性在短时间内均出现先升高然后下降的趋势.     

Effects of 1,2,4,6-<Emphasis Type=\"Italic\">tetra</Emphasis>-O-galloyl-β-D-glucose from <Emphasis Type=\"Italic\">P. emblica</Emphasis> on HBsAg and HBeAg secretion in HepG2.2.15 cell culture

A polyphenolic compound, 1,2,4,6-tetra-O-galloyl-β-D-glucose (1246TGG), was isolated from the traditional Chinese medicine Phyllanthus emblica L. (Euphorbiaceae) and assayed for its potential as an anti-hepatitis B virus (HBV) agent. The cytotoxicity of 1246TGG on HepG2.2.15 as well as HepG2 cells was determined by observing cytopathic effects, and the effects of 1246TGG on secretion of HBsAg and HBeAg in HepG2.2.15 cells were assayed by enzyme immunoassay. Results indicates that treatment with 1246TGG (6.25 μg/mL, 3.13 μg/mL), reduced both HBsAg and HBeAg levels in culture supernatant, yet the inhibitory effects tend to decline with the assay time. This study provides a basis for further investigation of the anti-HBV activity and possible mechanism of action of 1246TGG.     

抗寒剂CR—4对冬小麦幼苗质膜钙泵（Ca^2＋—ATPase）的稳定作用

通过磷酸铈沉淀的细胞化学观察揭示,常温下生长的冬小麦幼苗的Ｃａ２＋ＡＴＰ酶活性主要定位在质膜上,同时,水浸种和抗寒剂浸种的小麦质膜Ｃａ２＋ＡＴＰ酶活性没有差异。然而,小麦幼苗经－７℃冰冻处理１２小时和２４小时后,则表现明显的区别：水浸种的小麦幼苗质膜Ｃａ２＋ＡＴＰ酶活性明显下降,直至完全失活,细胞的精细结构也同时被破坏;而经抗寒剂浸种的小麦幼苗质膜Ｃａ２＋ＡＴＰ酶仍维持较高的活性,细胞结构也保持完整,显示抗寒剂对质膜Ｃａ２＋ＡＴＰａｓｅ酶起着明显的稳定作用。     

N-(2-氯-4-吡啶基)-N'-苯基脲(CPPU)对无疣墙藓原丝体发育与芽体发生的影响

0.2、0.4、1.0及1.5mg·L-1 4个浓度的N-(2-氯-4-吡啶基)-N'-苯基脲(CPPU)对无疣墙藓的孢子萌发没有显著影响,但抑制绿丝体伸长和侧枝生成,对芽体的分化有明显的促进,且芽体发生数随浓度升高而增加.     

鬼灯擎中丹宁类化合物的分离及结构的核磁共振分析（Ⅱ）

利用Toyopearl HW-40(C)凝胶反复柱层析,从鬼灯擎(Rodsersia aesculifolia Ba-tal.)根茎的70％Me_2CO提取物中分离得到六种丹宁类化合物,其中四种经化学及核磁共振分析分别确定其结构为3-0-没食子酰基-(-)-表儿茶素[3-0-galloyl-(-)-epicatechin]RA-11,1,3-0-没食子酰基-表儿茶素-(4β-8)-(3-0-没食子酰基)-表儿茶素[(3-0-galloyl)-epieatechin-(4β-8)-(3-0-Salloyl)-epicatechin]RA-13,2;1,2,4,6-四-0-没食子酰基-β-D-葡萄糖[1,2,4,6-tetra-0-galloyl-β-D-glucose]RA-14,3和没食子酸甲酯(methyl gallate)RA-16,4。RA-14为首次获得的结晶性没食子丹宁,这些成分均为首次从该植物中得到。     

腺梗豨莶的新双色满

作者从腺梗莶的乙醚抽出物中分到一个新的双色满成分 ,基于光谱分析和应用二维核磁共振技术 ,它的化学结构已被确定为 3,3’ 双 (3,4 二氢化 6 甲氧基 2H 1 苯并吡喃 )或 3,3’ 双 (6 甲氧基色满 )。     

特发性矮小症患儿治疗前后血清IGF-1、IGFBP-3、25（OH）D、皮质醇水平变化及其与体格发育和骨龄的相关性分析

摘要 目的：探究特发性矮小症（ISS）患儿治疗前后血清胰岛素样生长因子1（IGF-1）、胰岛素样生长因子结合蛋白3（IGFBP-3）、25羟维生素D[25（OH）D]、皮质醇水平变化及其与体格发育和骨龄的相关性。方法：选取安徽省儿童医院于2017年7月～2021年3月收治的88例ISS患儿作为研究组。另选取同期体检健康儿童88例作为对照组。比较两组血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平。比较ISS患儿治疗前后血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平,体格指标以及骨龄指标。通过Pearson相关性分析ISS患儿血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平与体格指标、骨龄指标的相关性。结果：研究组患儿血清IGF-1、IGFBP-3、25（OH）D水平均低于对照组,而皮质醇水平高于对照组（均P＜0.05）。ISS患儿治疗后血清IGF-1、IGFBP-3、25（OH）D水平均高于治疗前,而皮质醇水平低于治疗前（均P＜0.05）。ISS患儿治疗后身高、体重、骨龄年龄差（BAD）、骨龄指数（BAI）以及体质指数（BMI）均高于治疗前（均P＜0.05）。经Pearson相关性分析发现：ISS患儿血清IGF-1、IGFBP-3、25（OH）D水平与身高、体重、BAD、BAI以及BMI均呈正相关;皮质醇与身高、体重、BAD、BAI以及BMI均呈负相关（均P＜0.05）。结论：ISS患儿血清IGF-1、IGFBP-3、25（OH）D水平异常降低,皮质醇水平升高,且上述四项指标均和身高、体重、BAD以及BAI有关。     

大叶紫珠中得到的一个新苯丙素类衍生物（英文）北大核心CSCD

采用硅胶、ODS和葡聚糖凝胶LH-20柱层析方法,从大叶紫珠(马鞭草科)70%乙醇提取物的乙酸乙酯萃取部位得到一个新的苯丙素类衍生物。采用包括电喷雾离子化高分辨质谱和一维、二维核磁共振等多种光谱学手段鉴定该化合物结构为2-甲氧基对苯二酚-4-O-[(5-O-反式-咖啡酰)-β-D-呋喃芹菜糖]-(1→2)-β-D-吡喃葡萄糖苷。     

Light microscopic structure of DNA in solution studied by the 4′,6-diamidino-2-phenylindole staining method

Individual DNA molecules in solution can be visualized under a fluorescence microscope by using the DNA-binding dye 4′,6-diamidino-2-phenylindole and can be recorded on video as mobile structures (Morikawa & Yanagida, 1981). DNA in the presence of 10mm-MgCl₂ was found to adhere to the glass surface, so that 4′,6-diamidino-2-phenylindole-stained DNA can be filmed as still images. Fluorescence micrographs of DNA (bacteriophages T4, T3 and λ, yeast and chicken erythrocyte) taken by the present procedure are better in resolution than those obtained by video, showing structural details of DNA molecules hitherto not observed in solution. In the specimens prepared at the reduced shear stress, the folded particles and the short thick filaments were abundant. The shear stream extended them into the wavy and the straight thin filaments. The lengths of the thin filaments seen in viral DNA correlated well with those determined by electron microscopy. Our results suggest that a DNA molecule in solution forms a certain kind of supercoil of its own accord.     

Comparison of ethidium bromide and 4′,6-diamidino-2-phenylindole as quantitative fluorescent stains for DNA in agarose gels

Two methods of quantitative, fluorescent detection of DNA bands in agarose gels separated by electrophoresis were evaluated for sensitivity and linearity of response. Comparisons of ethidium bromide staining with a method using 4′,6-diamidino-2-phenylindole (DAPI) developed in this work showed that DAPI is several times more sensitive than ethidium bromide in conditions of comparable background flourescence. Optimum flourescent staining and detection conditions for DNA bands in agarose gels using DAPI are desctribed, and advantages of this method over other fluorescent detection methods are discussed.     

DAPI as a Useful Stain for Nuclear Quantitation

A simple-to-use fluorescent stain, 4′,6-diamidino-2-phenylindole (DAPI), visualizes nuclear DNA in both living and fixed cells. DAPI staining was used to determine the number of nuclei and to assess gross cell morphology. Following light microscopic analyses, the stained cells were processed for electron microscopy. Cells stained with DAPI showed no ultrastructural changes compared to the appearance of cells not stained with DAPI. DAPI staining allows multiple use of cells eliminating the need for duplicate samples.     

DAPI as a Useful Stain for Nuclear Quantitation

A simple-to-use fluorescent stain, 4',6-diamidino-2-phenylindole (DAPI), visualizes nuclear DNA in both living and fixed cells. DAPI staining was used to determine the number of nuclei and to assess gross cell morphology. Following light microscopic analyses, the stained cells were processed for electron microscopy. Cells stained with DAPI showed no ultrastructural changes compared to the appearance of cells not stained with DAPI. DAPI staining allows multiple use of cells eliminating the need for duplicate samples.     

Quantification of DNA synthesis in multicellular organisms by a combined DAPI and BrdU technique

The development of a novel method to detect and quantify mitotic activity in multicellular organisms is reported. The method is based on the combinatorial use of 4',6-diamidino-2-phenylindole (DAPI) as a dye for the specific staining of DNA and the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) as a marker for DNA synthesis. It is shown that on nitrocellulose filters, the amount of DNA can be determined by DAPI as a prerequisite for the subsequent quantification of mitotic activity by BrdU. As a model system to prove the applicability of this technique, the blood fluke Schistosoma mansoni has been used. It is demonstrated that the DNA synthesis rate is higher in adult female schistosomes than in adult males. Furthermore, dimethyl sulfoxide, a widely used solvent for many mitogens and inhibitors of mitosis, has no influence on mitotic activity in adult schistosomes.     

First Experimental Evidence for the Presence of a CRISPR Toxin in Sulfolobus

Clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated (cas) genes constitute the adaptive immune system in bacteria and archaea. Although the CRISPR-Cas systems have been hypothesized to encode potential toxins, no experimental data supporting the hypothesis are available in the literature. In this work, we provide the first experimental evidence for the presence of a toxin gene in the type I-A CRISPR system of hyperthermophilic archaeon Sulfolobus. csa5, under the control of its native promoter in a shuttle vector, could not be transformed into CRISPR-deficient mutant Sulfolobus solfataricus Sens1, demonstrating a strong toxicity in the cells. A single-amino-acid mutation destroying the intersubunit bridge of Csa5 attenuated the toxicity, indicative of the importance of Csa5 oligomerization for its toxicity. In line with the absence of Csa5 toxicity in S. solfataricus InF1 containing functional CRISPR systems, the expression of csa5 is repressed in InF1 cells. Induced from the arabinose promoter in Sens1 cells, Csa5 oligomers resistant to 1% SDS co-occur with chromosome degradation and cell death, reinforcing the connection between Csa5 oligomerization and its toxicity. Importantly, a rudivirus was shown to induce Csa5 expression and the formation of SDS-resistant Csa5 oligomers in Sulfolobus cells. This demonstrates that the derepression of csa5 and the subsequent Csa5 oligomerization take place in native virus-host systems. Thus, csa5 is likely to act as a suicide gene under certain circumstances to inhibit virus spreading.     

Measurement of bacterial volume by transmission-through-dye imaging

Transmission-through-dye (TTD) microscopy makes possible direct measurement of bacterial volume, irrespective of cell shape. The technique can be realized on any brightfield microscope and is applicable to bacteria of all shapes. TTD imaging requires that intact bacteria be immobilized on a flat transparent surface, such as a glass coverslip.