柳牡蛎蚧生命表的研究

1 引言 柳牡蛎蚧(Lepidosaphes salicina Bersch)(同翅目:盾蚧科)是一种以为害杨树为主的刺吸式害虫之一,广泛分布于“三北”防护林区,该蚧一年发生一代,以卵越冬。通过刺吸式口器刺入树皮内,吸取树木养分和水分,并使树木表皮栓化。同时,由于枝干被蚧壳所覆盖,对呼吸及光合作用也有影响,特别是幼树被害后,一般     

Five New Phenolic Glycosides from Viburnum luzonicum

Viburnum luzonicum is widely distributed in China. Its branch extracts showed potential α-amylase and α-glucosidase inhibitory activities. In order to discover new bioactive constituents, five undescribed phenolic glycosides, viburozosides A−E ( 1 – 5 ), were obtained by bioassay-guided isolation coupled with HPLC-QTOF-MS/MS analysis. Their structures were elucidated by spectroscopic analyses, including 1D NMR, 2D NMR, ECD, and ORD. All compounds were tested for their α-amylase and α-glucosidase inhibitory potency. Compound 1 showed significantly competitive inhibition against α-amylase (IC₅₀=17.5 μM) and α-glucosidase (IC₅₀=13.6 μM).     

Effect of Flowering Stages on the Content of Active Ingredients and Antioxidant Capability of Bletilla striata Flowers

Bletilla striata (Thunb.) Reichb.f. is a perennial herb with abundant active ingredients. Previous research mainly focused on its tubers, however, the study on flowers, especially the variation of active ingredient contents at different flowering stages, was rarely seen. This study analyzed the total phenols, flavonoids, polysaccharides, anthocyanins, and cyanidin-3-O-glucoside content of B. striata flowers which were in cultivated in Herb Garden of Zhejiang A&F University and collected in May, 2019, in order to investigate the changes in active ingredients and antioxidant capacity among different flowering stages (bud, initial, and full bloom). Changes in radical scavenging capability of DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), ABTS (2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonate)), and hydroxy were analyzed. Significant differences in active ingredient content of flowers were detected among different flowering stages. The total phenolic content increased continuously during the entire flowering stage. The contents of total flavonoid, total polysaccharide, and cyanidin-3-O-glucoside reached peaks at the initial blooming stage and then fell as the flowering process continued. The antioxidant activity in initial stage was the highest than in any other flowering stages. Therefore, we conclude that the initial blooming stage is the best harvesting stage of B. striata flowers. This study provides a robust basis for the harvest and utilization of B. striata flowers in food, medical, and cosmetic industries.     

栝楼核糖核酸酶在RNA序列分析中的应用

栝楼核糖核酸酶（RNase TCS）对U碱基具有高度的专一性,在无脲、pH3.5、50℃时,它几乎都在-NP ↓ U-处裂解RNA.它与RNase T1,U₂和有限的碱水解一起,可用于直接的酶法RNA序列分析．     

人类疱疹病毒6型可诱生TNF－α

用生物活性法和双抗体夹心桥联酶免疫吸附（ＥＬＩＳＡ）法检测了人类疱疹病素６型（ＨＨＶ－６）ＧＳ株和南京地方株ＣＮ５,８,１０感染的淋巴细胞培养上清中的肿瘤坏死因子（ＴＮＦ）的水平,发现培养２４ｈ即可检出高水平的ＴＮＦ,４８～７２ｈ述到峰值,此后逐渐下降,与未感染耐照组比较有及其显著的差异（Ｐ＜０．００１）。ＧＳ株与地方株同诱生ＴＮＦ水平无儿著性差异（Ｐ＞０．１）,三株地方株诱生ＴＮＦ也无显著性差异（Ｐ＞０．０５）。ＴＮＦ－α单抗可以完全中和培养上清中ＴＮＦ的活性,证实上清中有ＴＮＦ－α。与ＬＰＳ比较,ＨＨＶ－６诱生ＴＮＦ－α的能力要强得多。     

粘质赛氏菌胞外蛋白酶的提取、纯化及部分性质研究

经过硫酸铵３０％～５０％分级沉淀、二步柱层析可获聚丙烯酰胺凝胶电泳均一的粘质赛氏菌胞外蛋白酶制品,收率可达５３％,并制备了酶的结晶,该酶以ＳｅｐｈａｄｅｘＧ１００柱层析及ＳＤＳ－ＰＡＧＥ测得分子量约为８１０００,该酶的最适ｐＨ为７．０,最适温度为４５℃,Ｚｎ２＋、Ｍｎ２＋、Ｆｅ２＋、Ｃｕ２＋、Ｃｏ２＋等重金属离子不同程度地抑制酶活性。     

5-Azacytidine increases the activity of neomycin phosphotransferase II in transgenic Nicotiana tabacum: A posttranslational mechanism may play a role

In previous studies, tobacco protoplasts were transformed with the bacterial gene encoding neomycin phosphotransferase II (NPT II). Transformed calluses lost neomycin phosphotransferase II activity after several subcultures. Treatment of calluses with 5-azacytidine, a demethylating agent, restored enzyme activity, suggesting that methylation of npt II sequences might be responsible for loss of NPT II activity. Studies presented here were designed to test that hypothesis. Results indicated that the effect of 5-azacytidine could not be blocked by the DNA replication inhibitor, hydroxyurea, nor by the 5-azacytidine analogue, cytidine as would be expected with a DNA demethylation mechanism. The level of NPT II mRNA was not increased by 5-azacytidine. Treatment with cycloheximide, a protein synthesis inhibitor, had no effect on 5-azacytidine-increased NPT II activity. There was no increase of NPT II protein caused by 5-azacytidine, whereas 5-azacytidine increased activity of NPT II. In contrast, the auxin 2,4-D increased both the NPT II protein and activity. Assays for malate dehydrogenase demonstrated that the effect of 5-azacytidine and hydroxyurea on NPT II was not due to an overall effect on callus metabolism. In vitro studies involving standard bacterial NPT II enzyme and crude extracts from untreated and 5-azacytidine- or hydroxyurea-treated calluses showed that the activity of NPT II added to the untreated extracts was lower than the activity of NPT II added to the extracts from calluses treated with 5-azacytidine or hydroxyurea, indicating that there was an unknown factor (or factors) in callus extracts which affected the activity of NPT II and itself was affected by 5-azacytidine and hydroxyurea treatment. These results suggested that one effect of 5-azacytidine in increasing NPT II activity was posttranslational.Abbreviations ELISA enzyme-linked immunosorbent assay - NOS nopalene synthase - nos DNA segment encoding NOS - NPT II neomycin phosphotransferase - npt II DNA segment encoding NPT II - PAGE polyacrylamide gel electrophoresis     

大鼠不同脑区突触体钙水平的年龄差异

本实验使用荧光指示剂Ｆｕｒａ－２与Ｔｂ~（３＋）,检测了不同年龄组大鼠的不同脑区（海马、皮层、间脑、小脑）突触体内游离钙与膜结合钙水平。结果显示,与青年对照组相比,老年大鼠大部分脑区（海马、皮层、间脑）突触体内游离钙水平显著增高,尤其是海马突触体内游离钙增高极为显著;其突触体膜结合钙水平表现为：海马、小脑两脑区明显升高,而皮层、间脑两脑区明显下降,呈现一种全脑范围内的钙水平失衡。提示动物的衰老与其脑内钙自体平衡失调有关。