Competitive interactions between entomopathogenic nematodes and parasitoid venom

Entomopathogenic nematodes and parasitoid larvae of some wasps play important roles in the natural control of the pest insects. However, it has not been excluded that competition between nematodes and wasps may in some cases reduce their efficacy in the pest control. Using caterpillars of Spodoptera littoralis, we examined interactions between the nematode Steinernema carpocapsae and the venom of the parasitoid Habrobracon hebetor. The survival of S. littoralis caterpillars was reduced in a dose-dependent manner when 5 to 500 nematodes or 0.005–0.1 venom units were applied to single caterpillars. High doses of either nematodes or the venom caused death within 1–3 days in all treated hosts. The low doses of nematodes killed caterpillars within a week, in some cases when they attempted to pupate. Caterpillars receiving low venom doses were characterized by extended survival time terminated with death due to starvation. Combined treatment of nematodes and the venom were mutually synergistic and elicited severe lethal effects. The nematodes were fully resistant to the venom and can feed and grow on the symbiotic bacteria in vitro. The venom impairs food processing and causes death of caterpillars due to starvation. Disruption of the hormonal regulation of metamorphosis by ecdysteroids and juvenile hormone could be responsible for defective moults block at different stages of the moulting process, regionally restricted moulting, moults to “intermediates” combining regions of newly secreted larval and pupal cuticles.     

Human L-ficolin,a Recognition Molecule of the Lectin Activation Pathway of Complement,Activates Complement by Binding to Pneumolysin,the Major Toxin of Streptococcus pneumoniae

The complement system is an essential component of the immune response, providing a critical line of defense against different pathogens including S. pneumoniae. Complement is activated via three distinct pathways: the classical (CP), the alternative (AP) and the lectin pathway (LP). The role of Pneumolysin (PLY), a bacterial toxin released by S. pneumoniae, in triggering complement activation has been studied in vitro. Our results demonstrate that in both human and mouse sera complement was activated via the CP, initiated by direct binding of even non-specific IgM and IgG3 to PLY. Absence of CP activity in C1q^−/− mouse serum completely abolished any C3 deposition. However, C1q depleted human serum strongly opsonized PLY through abundant deposition of C3 activation products, indicating that the LP may have a vital role in activating the human complement system on PLY. We identified that human L-ficolin is the critical LP recognition molecule that drives LP activation on PLY, while all of the murine LP recognition components fail to bind and activate complement on PLY. This work elucidates the detailed interactions between PLY and complement and shows for the first time a specific role of the LP in PLY-mediated complement activation in human serum.     

Atrial Arrhythmia in Ageing Spontaneously Hypertensive Rats: Unraveling the Substrate in Hypertension and Ageing

Background

Both ageing and hypertension are known risk factors for atrial fibrillation (AF) although the pathophysiological contribution or interaction of the individual factors remains poorly understood. Here we aim to delineate the arrhythmogenic atrial substrate in mature spontaneously hypertensive rats (SHR).

Methods

SHR were studied at 12 and 15 months of age (n = 8 per group) together with equal numbers of age-matched normotensive Wistar-Kyoto control rats (WKY). Electrophysiologic study was performed on superfused isolated right and left atrial preparations using a custom built high-density multiple-electrode array to determine effective refractory periods (ERP), atrial conduction and atrial arrhythmia inducibility. Tissue specimens were harvested for structural analysis.

Results

Compared to WKY controls, the SHR demonstrated: Higher systolic blood pressure (p<0.0001), bi-atrial enlargement (p<0.05), bi-ventricular hypertrophy (p<0.05), lower atrial ERP (p = 0.008), increased atrial conduction heterogeneity (p = 0.001) and increased atrial interstitial fibrosis (p = 0.006) & CD68-positive macrophages infiltration (p<0.0001). These changes resulted in higher atrial arrhythmia inducibility (p = 0.01) and longer induced AF episodes (p = 0.02) in 15-month old SHR. Ageing contributed to incremental bi-atrial hypertrophy (p<0.01) and atrial conduction heterogeneity (p<0.01) without affecting atrial ERP, fibrosis and arrhythmia inducibility. The limited effect of ageing on the atrial substrate may be secondary to the reduction in CD68-positive macrophages.

Conclusions

Significant atrial electrical and structural remodeling is evident in the ageing spontaneously hypertensive rat atria. Concomitant hypertension appears to play a greater pathophysiological role than ageing despite their compounding effect on the atrial substrate. Inflammation is pathophysiologically linked to the pro-fibrotic changes in the hypertensive atria.     

Germline recombination in a novel Cre transgenic line,Prl3b1‐Cre mouse

Spermatogenesis is a complex and highly regulated process by which spermatogonial stem cells differentiate into spermatozoa. To better understand the molecular mechanisms of the process, the Cre/loxP system has been widely utilized for conditional gene knockout in mice. In this study, we generated a transgenic mouse line that expresses Cre recombinase under the control of the 2.5 kbp of the Prolactin family 3, subfamily b, member 1 (Prl3b1) gene promoter (Prl3b1‐cre). Prl3b1 was initially reported to code for placental lactogen 2 (PL‐2) protein in placenta along with increased expression toward the end of pregnancy. PL‐2 was found to be expressed in germ cells in the testis, especially in spermatocytes. To analyze the specificity and efficiency of Cre recombinase activity in Prl3b1‐cre mice, the mice were mated with reporter R26GRR mice, which express GFP ubiquitously before and tdsRed exclusively after Cre recombination. The systemic examination of Prl3b1‐cre;R26GRR mice revealed that tdsRed‐positive cells were detected only in the testis and epididymis. Fluorescence imaging of Prl3b1‐cre;R26GRR testes suggested that Cre‐mediated recombination took place in the germ cells with approximately 74% efficiency determined by in vitro fertilization. In conclusion, our results suggest that the Prl3b1‐cre mice line provides a unique resource to understand testicular germ‐cell development. genesis 54:389–397, 2016. © 2016 Wiley Periodicals, Inc.     

TTC染色鉴定葡萄抗寒性方法的优化与应用北大核心CSCD

以‘左山1号’、101-14、3309C、SO4、140R和‘黑比诺’等葡萄砧木和品种直径为0.5~0.7 cm的一年生枝条为材料,经低温梯度(0℃、-14℃、-19℃、-24℃、-29℃和-34℃)处理后,对TTC染色的温度和时间进行优化并观察统计葡萄枝条不同组织的存活情况,测定枝条的相对电导率,以及韧皮部和木质部的可溶性蛋白、游离脯氨酸、可溶性糖、淀粉含量和束缚水自由水比例(束自比)5个生理指标,分别用枝条纵切面染色面积、相对电导率拟合Logistic方程计算枝条的半致死温度(LT_(50))来评价枝条的抗寒性,同时通过隶属函数法综合评价枝条韧皮部和木质部抗寒性,并将3种方法的评价结果进行比较,以建立一种直观高效鉴定葡萄品种抗寒性的方法。结果表明:(1)依据低温胁迫下各品种葡萄砧木扦插枝条的萌芽率和生根率表现,其抗寒性由强到弱依次为‘左山1号’、101-14、3309C、SO4、140R和‘黑比诺’。(2)葡萄枝条TTC活力染色的最佳条件为pH=7.0,0.5%TTC-0.1 mol/L磷酸缓冲液在35℃下避光染色36 h。随着胁迫温度的降低,各品种枝条纵切面染色面积均逐渐降低,根据优化TTC法获得‘左山1号’、101-14、3309C、SO4、140R和‘黑比诺’枝条的LT_(50)分别为-31.38℃、-26.51℃、-26.10℃、-23.60℃、-23.33℃和-19.26℃。(3)随着胁迫温度的降低,各品种枝条的相对电导率逐渐增加,且‘黑比诺’的相对电导率基本保持最高、增幅最大(51.93%),而‘左山1号’的相对电导率始终最低、增幅最小(44.07%);根据相对电导率获得‘左山1号’、101-14、3309C、SO4、140R和‘黑比诺’枝条的LT_(50)分别为-30.02℃、-26.40℃、-25.75℃、-23.16℃、-21.13℃和-17.72℃。(4)通过5种生理指标进行枝条抗寒性隶属函数综合性评价结果显示,同一品种中韧皮部抗寒性强于木质部,同一部位不同品种的抗寒性表现为:‘左山1号’>101-14>3309C>SO4>140R>‘黑比诺’。研究发现,TTC染色法与电导法和综合隶属函数法获得的葡萄枝条抗寒力评价结果一致,也与枝条生长恢复鉴定结果一致;但与其他两种方法相比,TTC染色法能更加直观和有效地预测评估葡萄枝条的抗寒性。     

Aspirin inhibits cancer stem cells properties and growth of glioblastoma multiforme through Rb1 pathway modulation

Several clinical studies indicated that the daily use of aspirin or acetylsalicylic acid reduces the cancer risk via cyclooxygenases (Cox-1 and Cox-2) inhibition. In addition, aspirin-induced Cox-dependent and -independent antitumor effects have also been described. Here we report, for the first time, that aspirin treatment of human glioblastoma cancer (GBM) stem cells, a small population responsible for tumor progression and recurrence, is associated with reduced cell proliferation and motility. Aspirin did not interfere with cell viability but induced cell-cycle arrest. Exogenous prostaglandin E₂ significantly increased cell proliferation but did not abrogate the aspirin-mediated growth inhibition, suggesting a Cox-independent mechanism. These effects appear to be mediated by the increase of p21 ^waf1 and p27 ^Kip1, associated with a reduction of Cyclin D1 and Rb1 protein phosphorylation, and involve the downregulation of key molecules responsible for tumor development, that is, Notch1, Sox2, Stat3, and Survivin. Our results support a possible role of aspirin as adjunctive therapy in the clinical management of GBM patients.     

Inhibition of some hepatic glycosidases by the diseco nucleoside, 4-amino-3-(D-glucopentitol-1-yl)-5-mercapto-1,2,4-triazole and its 3-methyl analog

The in vivo and in vitro effects of 4-amino-3-(D-glucopentitol-1-yl)-5-mercapto-1,2,4-triazole and its 3-methyl analogue on alpha- and beta-glucosidases, beta-glucuronidase as well as alpha-amylase have been investigated. alpha-Glucosidase is the enzyme that is markedly affected in vivo and in vitro in a dose-dependent manner. The compounds showed a reversible inhibition of a competitive type for alpha-glucosidase. Moreover, they exert a relatively potent inhibition on alpha-glucosidase with a Ki magnitude of 3.6 x 10(-4), 9.5 x 10(-5) M.