Effects of toxins from two strains of Verticillium lecanii (Hyphomycetes) on bioattributes of a predatory ladybeetle, Delphastus catalinae (Col., Coccinellidae)

Abstract:  The aim of this study was to test the hypothesis that the whitefly ( Bemisia tabaci ; Hom., Aleyrodidae) predator ladybird beetles, Delphastus catalinae (Col., Coccinellidae), are not adversely affected in the field by the crude insecticidal toxins extracted from two strains of the fungus Verticillium lecanii , V3450 and Vp28. We developed a method to evaluate sublethal toxicity and its effects on consumption and functional response of D. catalinae . The crude toxins have low toxicity against beetle larva with LC₅₀ values of 1942 (1393–2710) and 2471 (1291–4731) p.p.m., respectively (approximately 10- and 12-fold of field rate of application 200 p.p.m.). The adult beetles had less sensitivity to crude toxins with LC₅₀ values of 4260 (3376–5375) and 4426 (1734–11298) p.p.m., respectively (approximately 20- and 22-fold of field rate 200 p.p.m.). The consumption and foraging capacity were significantly impaired especially in the second-instar larval beetles which took longer time (more than twice of the control beetles) to consume whitefly eggs after exposure to toxins, although D. catalinae suffered no significant effect on fecundity and longevity, when exposed to a toxin dilution of field rate. The data suggest that spraying of V. lecanii or its toxins should be avoided in the field having immature stages of D. catalinae .     

c-MYC调节的miRNA-92b在结直肠癌发生发展中的功能及机制探究

microRNAs(miRNAs)在参与癌症发生、发展过程中起着十分重要的作用．目前,miR-92b在结直肠癌中的作用及相关机制还未见报道．本研究探讨了miR-92b在结直肠癌发生发展中的功能及潜在机制．采用RT-qPCR方法发现,miR-92b在人结直肠癌临床样本中与癌旁组织相比显著高表达．通过结肠癌细胞株SW620稳转细胞及裸鼠皮下成瘤模型,发现过表达miR-92b可以显著促进细胞增殖及体内肿瘤生长．同时还发现miR-92b可以分泌形式存在于胞外及外周血中,提示miR-92b是一个具有分泌特性的microRNA． 在分子机理方面,c-MYC可通过调节miR-92b的启动子活性从而促进后者转录,并且c-MYC在结直肠癌组织样本中也存在高表达．进一步,通过在线预测、报告质粒活性检测及蛋白质印迹技术证实FBXW7是一个新的miR-92b靶基因．由于FBXW7已报道为c-MYC泛素降解过程中的关键泛素化连接酶之一,本研究结果提示结直肠癌中c-MYC、miR-92b及FBXW7三者间可能存在分子调节环路．综上所述,本研究为miR-92b在结直肠癌中的功能及机制提供了新的视角,并为miR-92b在结直肠癌早期诊断中的应用提供了新的参考．     

Biological Parameters of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) Fed on Rabbits,Sheep, and Cattle

In order to determine the effect of various hosts on feeding performance of Rhipicephalus (Boophilus) microplus, we used 3 mammalian species as hosts, cattle (Qinchuan), sheep (T an), and rabbits (Japanese white rabbit) for infest-ing ticks. Five hundreds of R. microplus larvae were exposed to each animal (3 animals/host species). Tick recoveries were 11.0%, 0.47%, and 5.5% from cattle, sheep, and rabbits, respectively. The averages of tick feeding periods were not significantly different on cattle, sheep, and rabbits, 28.8, 25.3, and 26.7 days, respectively. The average weights of individual engorged female from cattle, sheep, and rabbits were 312.5, 219.1, and 130.2 mg, respectively and those of egg mass weights each to 85.0, 96.6, and 17.8 mg. The highest egg hatching rate was in the ticks from cattle (96.0%), fol-lowed by those from rabbits (83.0%) and sheep (19.2%). These data suggest that rabbits could be as an alternative host to cultivate R. microplus for evaluating vaccines and chemical and biological medicines against the tick in the laboratory, although the biological parameters of ticks were less than those from cattle.     

Elevated p62/SQSTM1 determines the fate of autophagy-deficient neural stem cells by increasing superoxide

Autophagy plays important roles in many biological processes, but our understanding of the mechanisms regulating stem cells by autophagy is limited. Interpretations of earlier studies of autophagy using knockouts of single genes are confounded by accumulating evidence for other functions of many autophagy genes. Here, we show that, in contrast to Fip200 deletion, inhibition of autophagy by deletion of Atg5, Atg16L1, or Atg7 does not impair the maintenance and differentiation of postnatal neural stem cells (NSCs). Only Fip200 deletion, but not Atg5, Atg16L1, or Atg7 deletion, caused p62/sequestome1 aggregates to accumulate in NSCs. Fip200 and p62 double conditional knockout mice demonstrated that p62 aggregate formation triggers aberrant superoxide increases by impairing superoxide dismutase functions. By comparing the inhibition of autophagy by deletion of Atg5, Atg16L1, or Atg7 with Fip200 deletion, we revealed a critical role of increased p62 in determining the fate of autophagy-deficient NSCs through intracellular superoxide control.     

黄腹山鹪莺育雏行为和雏鸟生长

2007年3~9月,在广东省肇庆市江溪村对黄腹山鹪莺(Prinia flaviventris)的育雏行为和雏鸟生长进行了研究。通过取食行为观察、育雏食物分析和雏鸟身体量度的测量来研究黄腹山鹪莺亲鸟繁殖投资和雏鸟的生长规律。研究期间,利用隐蔽帐观察窗进行行为观察,观察距离在5 m以内;在雏鸟身体上用无味彩笔标号以区别雏鸟个体:10日龄前,标记于雏鸟背部,10~12日龄,标记在雏鸟跗跖处;对部分数据进行双变量相关分析,利用Logistic曲线拟合雏鸟形态增长,并比较每个回归方程斜率间的差异。结果显示:1)黄腹山鹪莺育雏由雌雄共同承担,育雏期(11.9±0.4)d(n=7巢)。幼雏出壳后亲鸟早晚暖雏,第7天起亲鸟白天不再暖雏;2)随雏鸟的生长,喂食次数和食物种类逐渐增加,雏鸟日龄与喂食次数极显著相关(r=0.995,P0.01);3)育雏期雏鸟食物皆为动物性食物,以蜘蛛目物种所占比例最大(40.95%),其他包括幼虫及直翅目、鳞翅目、鞘翅目、蜻蜓目等节肢动物;4)Logistic曲线方程中,体重的生长率常数k值最大,与其他k值之间存在显著性差异(P0.05);5)黄腹山鹪莺体重、体长、尾长、翼长、嘴峰、嘴裂、第三根初级飞羽(简称为P3)、跗跖及爪各参数间的相关系数均为0.9以上(P0.01),参数之间在一定程度上可相互代替;6)黄腹山鹪莺雏鸟的发育遵循最重要的功能优先发育的原则,符合能量分配假说。黄腹山鹪莺喂食次数、雏鸟生长速率(k值)相对较高,可能与当地丰富的食物资源有关,也可能是对巢址环境多变的适应。