Immunohistochemical localization of 36 and 29 kDa proteins in sparganum.

Antigenic proteins of 36 and 29 kDa were localized in Spirometra mansoni plerocercoid (sparganum) immunohistochemically by avidin biotin complex (ABC) staining. When polyclonal antibodies such as BALB/c mouse serum immunized with crude saline extract of sparganum or confirmed sparganosis sera were reacted as primary antibodies, the positive chromogen (3-amino, 9-ethylcarbazole) reactions were recognized at syncytial tegument, tegumental cells, muscle and parenchymal cells and lining cells of excretory canals. A monoclonal antibody (MAb) which was reacting to 36 and 29 kDa proteins in the extract of the worm was localized at the syncytial tegument and tegumental cells. The present results suggested that the potent antigenic proteins of 36 and 29 kDa in sparganum were produced at the tegumental cells and transported to the syncytial tegument.     

华东地区黑果蝇自然群体同工酶遗传多态的研究

我们用标准垂直板聚丙烯酰胺凝胶电泳和水平板琼脂糖凝胶电泳技术检测了黑果蝇(D.virilis)在合肥、芜湖、九江、南昌、福州、泉州和常州7个自然群体中Est-α、Est-β、Amy、Acph和α-Gpdh 5个座位的遗传变异,发现Est-α、Est-β和Amy 3个座位是高度多态的,Acph、α-Gpdh两个座位则是单态的。根据这5个座位等位基因的频率,我们计算了群体间的遗传距离。综合何朝珍报道的宁波、杭州、南京和洪泽4个群体的结果和我们的结果,我们作出系统树并发现泉州、福州两群体和其他群体在基因频率的分布和遗传距离方面有显著差异;分析显示这种差异与群体间地理隔离有关。     

Interaction of mutagenic spermidine-nitrous acid reaction products with uvr- and recA-dependent repair systems in Salmonella.

It has been observed previously that the mutagenic action of nitrous acid may be potentiated by polyamines. We examined the cellular response of two deoxyribonucleic acid repair systems to treatment with spermidine-nitrite reaction products. uvrB- deficient mutants of Salmonella typhimurium LT2 showed enhanced lethal and mutagenic response to the reaction products. Lethal activity was further enhanced in a uvrB recA double mutant, whereas mutagenic activity was not detectable. Dependence of mutagenesis on the recA gene implicates the action of an error-prone repair system in the fixation of a premutagenic lesion as a mutation. From consideration of the substrate characteristics of the two repair systems studied, it is suggested that the deoxyribonucleic acid lesion formed by the reaction products of spermidine and nitrite is an intrastrand cross-link.     

The novel peptide NbPPI1 identified from Nicotiana benthamiana triggers immune responses and enhances resistance against Phytophthora pathogens

In plants, recognition of small secreted peptides, such as damage/danger‐associated molecular patterns (DAMPs), regulates diverse processes, including stress and immune responses. Here, we identified an SGPS (Ser‐Gly‐Pro‐Ser) motif‐containing peptide, Nicotiana tabacum NtPROPPI, and its two homologs in Nicotiana benthamiana, NbPROPPI1 and NbPROPPI2. Phytophthora parasitica infection and salicylic acid (SA) treatment induced NbPROPPI1/2 expression. Moreover, SignalP predicted that the 89‐amino acid NtPROPPI includes a 24‐amino acid N‐terminal signal peptide and NbPROPPI1/2‐GFP fusion proteins were mainly localized to the periplasm. Transient expression of NbPROPPI1/2 inhibited P. parasitica colonization, and NbPROPPI1/2 knockdown rendered plants more susceptible to P. parasitica. An eight‐amino‐acid segment in the NbPROPPI1 C‐terminus was essential for its immune function and a synthetic 20‐residue peptide, NbPPI1, derived from the C‐terminus of NbPROPPI1 provoked significant immune responses in N. benthamiana. These responses led to enhanced accumulation of reactive oxygen species, activation of mitogen‐activated protein kinases, and up‐regulation of the defense genes Flg22‐induced receptor‐like kinase (FRK) and WRKY DNA‐binding protein 33 (WRKY33). The NbPPI1‐induced defense responses require Brassinosteroid insensitive 1‐associated receptor kinase 1 (BAK1). These results suggest that NbPPI1 functions as a DAMP in N. benthamiana; this novel DAMP provides a potentially useful target for improving plant resistance to Pytophthora pathogens.     

A secreted ribonuclease effector from Verticillium dahliae localizes in the plant nucleus to modulate host immunity

The arms race between fungal pathogens and plant hosts involves recognition of fungal effectors to induce host immunity. Although various fungal effectors have been identified, the effector functions of ribonucleases are largely unknown. Herein, we identified a ribonuclease secreted by Verticillium dahliae (VdRTX1) that translocates into the plant nucleus to modulate immunity. The activity of VdRTX1 causes hypersensitive response (HR)‐related cell death in Nicotiana benthamiana and cotton. VdRTX1 possesses a signal peptide but is unlikely to be an apoplastic effector because its nuclear localization in the plant is necessary for cell death induction. Knockout of VdRTX1 significantly enhanced V. dahliae virulence on tobacco while V. dahliae employs the known suppressor VdCBM1 to escape the immunity induced by VdRTX1. VdRTX1 homologs are widely distributed in fungi but transient expression of 24 homologs from other fungi did not yield cell death induction, suggesting that this function is specific to the VdRTX1 in V. dahliae. Expression of site‐directed mutants of VdRTX1 in N. benthamiana leaves revealed conserved ligand‐binding sites that are important for VdRTX1 function in inducing cell death. Thus, VdRTX1 functions as a unique HR‐inducing effector in V. dahliae that contributes to the activation of plant immunity.     

Design,synthesis, and biological evaluation of novel carbazole derivatives as potent DNMT1 inhibitors with reasonable PK properties

The DNA methyltransferases (DNMTs) were found in mammals to maintain DNA methylation. Among them, DNMT1 was the first identified, and it is an attractive target for tumour chemotherapy. DC_05 and DC_517 have been reported in our previous work, which is non-nucleoside DNMT1 inhibitor with low micromolar IC₅₀ values and significant selectivity towards other S-adenosyl-_L-methionine (SAM)-dependent protein methyltransferases. In this study, through a process of similarity-based analog searching, a series of DNMT1 inhibitors were designed, synthesized, and evaluated as anticancer agents. SAR studies were conducted based on enzymatic assays. And most of the compounds showed strong inhibitory activity on human DNMT1, especially WK-23 displayed a good inhibitory effect on human DNMT1 with an IC₅₀ value of 5.0 µM. Importantly, the pharmacokinetic (PK) profile of WK-23 was obtained with quite satisfying oral bioavailability and elimination half-life. Taken together, WK-23 is worth developing as DNMT1-selective therapy for the treatment of malignant tumour.     

长春花黄化植原体（PY）株系的检测与鉴定

植原体 (Ｐｈｙｔｏｐｌａｓｍａ) (原称类菌原体Ｍｙｃｏｐｌａｓｍａ ｌｉｋｅＯｒｇａｎｉｓｍ ,简称ＭＬＯ)是一类无细胞壁、存在于植物筛管细胞内的原核生物。植原体自 1 967年被日本学者土居养二首次发现后 ,迄今为止 ,世界上报道的植物植原体病害多达 30 0余种 ,早期对植原体的鉴定主要是通过生物学特性 ,如症状特征、与昆虫介体的相互关系等进行的。这些方法费时费力 ,结果往往也不是很可靠。 80年代 ,随着血清学、分子探针以及ＰＣＲ技术的发展应用 ,为植原体的检测提供了一种相对简单、灵敏、可靠的方法。通过对 1 6ＳｒＲＮＡ基…     

Myokine IL-15 regulates the crosstalk of co-cultured porcine skeletal muscle satellite cells and preadipocytes

The present study was carried out to preliminarily reveal the underlying mechanisms of the co-culture system between porcine muscle satellite cells (SCs) and stromal-vascular cells (SVs). The two cell types were co-cultured to assess both proliferation and differentiation. Desmin and Pref-1 immunofluorescence staining technique were taken to identify the two types of isolated cells. The expression of specific marker genes Myogenin was up-regulated in SCs (P < 0.05) and the differentiation of SCs could be promoted when co-cultured with preadipocytes compared with the single-cultured control, while expression of c/EBPβ in SVs was down-regulated (P < 0.05) and the differentiation of preadipocytes could be inhibited. Furthermore, secretion of myokine IL-15 was markedly increased, as well as its gene and protein expression levels in co-culture supernatants. However, the secretion of adipokine leptin was significantly decreased. These findings demonstrate that myokines like IL-15 could facilitate the SCs’ differentiation while inhibit the SVs differentiation, and act as an important regulator of co-culture between muscle cells and adipocytes.     

脉冲电场对人红细胞膜结构影响的冷冻断裂研究

对外加脉冲电场处理的人红血球冷冻断裂和蚀刻的复型观察中发现在强电场(3KV/cm)作用下,细胞周围有颗粒状和纤维状结构。结合SDS电泳分析证明了它们是由于在电场作用下,红血球膜的带3蛋白和膜骨架蛋白(血影蛋白)脱出的结果。在强电场作用下,由于膜蛋白和膜骨架蛋白的脱出造成了对细胞膜的损伤,使细胞膜稳定性降低,细胞易变形和形成伪足。由于膜蛋白的脱出,多余的自由脂质进入细胞质内而形成泡状结构。外电场改变了蛋白-蛋白以及蛋白-脂分子间的作用可能是电穿孔的主要机理。本文还对当前公认的冷冻断裂中所观察到的膜中间颗粒的来源提出了疑问,并提出了它们还可能与冰晶有关。而冰晶的形成又与膜的亲水与疏水性有关。