Induction of phenylalanine ammonia-lyase and lipoxygenase in cotton seedlings by mechanical wounding and aphid infestation

It has been suggested that infestation of plants causes increases in the activities of phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX), key enzymes in the phenolic compounds synthesis pathway and the octadecanoid pathway, respectively. The purpose of this work is to investigate whether the infestation of cotton aphid （Aphis gossypii） and mechanical wound can cause the induction of PAL and LOX activities in cotton seedlings, and whether the induction occurs in healthy seedlings growing nearby the attacked ones. The specific activities of PAL and LOX were measured using spectrophotometric method after aphid infestation and mechanical wounding. Result indicated that PAL activity and LOX activity were greatly induced by mechanical wounding and aphid infestation in cotton seedlings. The induction of PAL and LOX occurred not only in wounded and infested seedlings but also in intact healthy seedlings growing nearby. After exposed to the aphid infestation-induced volatiles, the specific activity of PAL in cotton seedlings increased by 6% at 24 h, 80% at 48 h, 235% at 72 h compared to the control, and the specific activity of LOX increased by 18% at 24 h, 34% at 48 h, 24% at 72 h, respectively. In comparison, the specific activity of PAL in unwounded seedlings exposed to wound-induced volatiles increased by 0.0 at 24 h, 200% at 48 h, 164% at 72 h, respectively and the specific activity of LOX increased by 28% at 24 h, 37% at 48 h, 8% at 72 h, respectively. It suggests that the induced volatiles are involved in plant-plant communication as airborne transferred signals.     

十一星瓢虫捕食棉蚜的种群动力学模型及其数值模拟

根据棉蚜、十一星瓢虫的生物学特性以及新疆棉区十一星瓢虫对棉蚜捕食作用的调查和实验数据,建立了十一星瓢虫捕食棉蚜的种群动力学理论模型.在模型中对捕食者─十一星瓢虫进行了虫态和年龄结构划分,用来模拟不同虫态和年龄结构瓢虫对蚜虫的捕食.运用有限差分法对建立的模型进行了数值模拟,将模拟结果与实际调查数据进行比较,验证了模型的准确性和实用性.     

Heat shock enhances thermotolerance of infective juvenile insect-parasitic nematodesHeterorhabditis bacteriophora (Rhabditida: Heterorhabditidae)

Insect-parasitic nematodes possess many of the attributes of ideal biological control agents, but intolerance to extreme temperatures can restrict their use. We examined whether heat-shock treatments could improve nematode survival and infectivity at temperatures that normally inhibit their activity (35 and 40°C). Nematodes exposed to a sub-lethal temperature (35°C) for 3 h with a latency period of 1–2 h at 25°C killed insects at 35 and 40°C. Correlative evidence was obtained between increased thermotolerance and the synthesis of 70-kDa heat-shock proteins (hsps). These results provide the first evidence of hsp synthesis in the development of thermotolerance and biological activity in the non-feeding, developmentally arrested, infective juvenile nematodes.     

野苋菜凝集素基因的克隆及抗蚜性

通过PCR从苋科植物野苋菜Amaranthus viridis L.基因组DNA中扩增出野苋菜凝集素的核基因片段AVA。序列分析结果表明该基因为1831 bp,含有一个922 bp的内含子和两个分别为212 bp和697 bp的外显子。采用反向PCR技术获得了该基因的编码区克隆。分别构建含有内含子和不含内含子的AVA基因植物表达载体pBI121AVA-GUS和pBI121AVAc-GUS,通过根癌农杆菌介导法转化烟草。PCR、GUS检测结果均表明AVA基因不仅已整合到烟草基因组DNA中,而且初步表明转基因烟草有AVA蛋白表达。抗蚜实验表明含内含子和无内含子的AVA基因在转基因烟草中的抗蚜能力不同,转AVA和AVAc烟草对蚜虫的抑制率分别为60.81%和50.63%,有的植株高达97%。实验结果表明所克隆的AVA基因是具有抗蚜能力的苋菜凝集素基因家族中的新成员。     

外源性透明质酸减少R5-HIV对CD4~+T细胞感染的研究（英文）

目的探讨外源性透明质酸(HA)是否可以降低巨噬细胞嗜性(CCR5依赖,R5)人类免疫缺陷病毒(HIV)对CD4+T细胞的感染性。方法首先用TZM-bl细胞和未受刺激的CD4+T细胞检测,以评估外源性透明质酸(HA)能否降低R5-HIV的感染性。用透明质酸酶去处理未受刺激的CD4+T细胞,研究内源性HA对R5-HIV感染性的影响。最后,同时测量外源性和内源性透明质酸(HA)对R5-HIV对CD4+T细胞粘和力的影响。结果 (1)100μg外源性HA处理能够显著降低R5-HIV感染TZM-bl细胞和未受刺激的CD4+T细胞(P<0.001)。(2)透明质酸酶处理可增强HIV的感染性,但是如果加上100μg外源性HA可以逆转透明质酸酶的处理(P<0.001)。(3)100μg外源性HA可以减少R5-HIV对CD4+T细胞的粘和力,透明质酸酶处理可以提高R5-HIV对CD4+T细胞的粘和力(P<0.001)。结论外源性HA减少R5-HIV对未受刺激的CD4+T细胞的感染性,而透明质酸酶处理可以提高R5-HIV对CD4+T细胞的粘和力,能增强R5-HIV对CD4+T细胞的感染性。