生防细菌CNY-04筛选、鉴定及其对灰霉病菌的防效

【目的】为研究土壤细菌对蔬菜灰霉病的生防价值, 从辽宁、山东等地区的蔬菜种植基地采集土壤样本56份, 分离、筛选出对灰霉病具有稳定拮抗作用的细菌9株。【方法】采用平板对峙培养法进行初筛、复筛, 用抑菌圈法测定其抑菌效果, 并进行离体果实试验验证其对蔬菜灰霉病的防治效果, 通过形态学特征、生理生化特征及16S rRNA基因序列分析研究其分类地位。【结果】细菌CNY-04对蔬菜灰霉病的拮抗能力最强且遗传稳定, 抑菌圈直径达到34 mm; 初步鉴定该菌株为格氏沙雷菌(Serratia grimesii), 尚未见该菌在生防上的报道; CNY-04液体菌剂对离体番茄果实灰霉病的防效为69.23%, 50%多菌灵防效为75.39%, 24 h时接种CNY-04处理的番茄发病率为40.0%, 而48 h时接种处理的发病率为51.1%。【结论】CNY-04是一株较为理想的拮抗菌, 丰富了生防资源。     

Characterization of Novel CSF Tau and ptau Biomarkers for Alzheimer’s Disease

Cerebral spinal fluid (CSF) Aβ42, tau and p181tau are widely accepted biomarkers of Alzheimer’s disease (AD). Numerous studies show that CSF tau and p181tau levels are elevated in mild-to-moderate AD compared to age-matched controls. In addition, these increases might predict preclinical AD in cognitively normal elderly. Despite their importance as biomarkers, the molecular nature of CSF tau and ptau is not known. In the current study, reverse-phase high performance liquid chromatography was used to enrich and concentrate tau prior to western-blot analysis. Multiple N-terminal and mid-domain fragments of tau were detected in pooled CSF with apparent sizes ranging from <20 kDa to ~40 kDa. The pattern of tau fragments in AD and control samples were similar. In contrast, full-length tau and C-terminal-containing fragments were not detected. To quantify levels, five tau ELISAs and three ptau ELISAs were developed to detect different overlapping regions of the protein. The discriminatory potential of each assay was determined using 20 AD and 20 age-matched control CSF samples. Of the tau ELISAs, the two assays specific for tau containing N-terminal sequences, amino acids 9-198 (numbering based on tau 441) and 9-163, exhibited the most significant differences between AD and control samples. In contrast, CSF tau was not detected with an ELISA specific for a more C-terminal region (amino acids 159-335). Significant discrimination was also observed with ptau assays measuring amino acids 159-p181 and 159-p231. Interestingly, the discriminatory potential of p181 was reduced when measured in the context of tau species containing amino acids 9-p181. Taken together, these results demonstrate that tau in CSF occurs as a series of fragments and that discrimination of AD from control is dependent on the subset of tau species measured. These assays provide novel tools to investigate CSF tau and ptau as biomarkers for other neurodegenerative diseases.     

Malaria parasite liver stages render host hepatocytes susceptible to mitochondria-initiated apoptosis

Intracellular eukaryotic parasites and their host cells constitute complex, coevolved cellular interaction systems that frequently cause disease. Among them, Plasmodium parasites cause a significant health burden in humans, killing up to one million people annually. To succeed in the mammalian host after transmission by mosquitoes, Plasmodium parasites must complete intracellular replication within hepatocytes and then release new infectious forms into the blood. Using Plasmodium yoelii rodent malaria parasites, we show that some liver stage (LS)-infected hepatocytes undergo apoptosis without external triggers, but the majority of infected cells do not, and can also resist Fas-mediated apoptosis. In contrast, apoptosis is dramatically increased in hepatocytes infected with attenuated parasites. Furthermore, we find that blocking total or mitochondria-initiated host cell apoptosis increases LS parasite burden in mice, suggesting that an anti-apoptotic host environment fosters parasite survival. Strikingly, although LS infection confers strong resistance to extrinsic host hepatocyte apoptosis, infected hepatocytes lose their ability to resist apoptosis when anti-apoptotic mitochondrial proteins are inhibited. This is demonstrated by our finding that B-cell lymphoma 2 family inhibitors preferentially induce apoptosis in LS-infected hepatocytes and significantly reduce LS parasite burden in mice. Thus, targeting critical points of susceptibility in the LS-infected host cell might provide new avenues for malaria prophylaxis.     

Intraluteal release of angiotensin II and progesterone in vivo during corpora lutea development in the cow: effect of vasoactive peptides.

The newly formed corpus luteum (CL) develops rapidly and has the features of active vascularization and mitosis of steroidogenic cells. Such local mechanisms must be strictly regulated by the complex relationship between angiogenic growth factors and vasoactive peptides such as angiotensin (Ang) II, atrial natriuretic peptide (ANP), and endothelin (ET)-1. Thus, the objective of the present study was to determine 1) the changes in vasoactive peptides and progesterone (P) concentrations within the developing CL, along with the changes in concentration in ovarian venous plasma (OVP) and jugular venous plasma (JVP) in the cow, 2) the effects of CL exposure to vasoactive peptides on Ang II and P secretion, and 3) the expression of mRNA for ANP type C receptor in the bovine CL and endothelial cells (ETC) from bovine developing CL. A microdialysis system (MDS) was surgically implanted into multiple CL of six cows on Day 3 after a GnRH injection that induced superovulation, and a catheter was simultaneously inserted into the ovarian vein. The Ang II concentration in OVP was higher than that in JVP throughout the experiment, while the intraluteal release of Ang II was stable. During the experimental period, the concentrations of other vasoactive peptides (ANP and ET-1) showed no clear changes in plasma and were below detectable levels in the MDS perfusate. Exposure of CL to Ang II using the MDS stimulated P release, while exposure to ANP enhanced Ang II release within the developing CL. However, ET-1 had no effect on either P or Ang II release. The expression of mRNA for ANP type C receptor was mainly observed in early CL and ETC. The results suggest that the ET-Ang-ANP system in the preovulatory follicle switches to an Ang-ANP system to enhance both the angiogenesis and steroidogenesis that are actively occurring in developing CL.     

Regulatory changes of apoptotic factors in the bovine corpus luteum after induced luteolysis

The corpus luteum (CL) offers the opportunity to study not only proliferative, but also regressive processes. During luteolysis of the CL a sudden death of luteal and endothelial cells seems to be involved (apoptosis). The aim of this study was to examen the mRNA expression of factors known to be involved in apoptotic processes: monocyte chemoattractant protein-1 (MCP-1), factors of the extrinsic and intrinsic apoptotic pathways, caspase3, -6, -7 and interferone gamma (IFNgamma). Luteolysis was induced by injection of 500 microg Cloprostenol during mid-luteal phase. The CLs were collected at 0.5, 2, 4, 12, 24, 48, and 64 hr after PGF2alpha-injection. Control CLs (Days 8-12) were collected at the slaugtherhouse. Real-time RT-PCR determined the mRNA expressions. Western blot analysis of poly(ADP-ribose) polymerase (PARP-1) and IFNgamma as well as protein measurement of tumor necrosis factor alpha (TNFalpha) by EIA were performed. The mRNA levels of MCP-1, IFNgamma and most factors of the extrinsic pathway were significantly increased between 0.5 and 2 hr. The factors of the intrinsic pathway were mostly later up-regulated at 24-48 hr after PGF2alpha. Caspase6 and 3 revealed a significant increase from 2 and 12 hr, respectively, whereas caspase7 was significantly up-regulated after 24 hr. The protein level of TNFalpha increased significantly to a maximum level at 12 hr. The Western blot revealed an increasing level of an 89 kDa fragment of PARP-1 from 12 to 24 hr, which is specific for apoptosis. We assume that the extrinsic pathway is more important for the onset of luteolysis, because of its earlier and higher increase during induced luteolysis.