Susceptibility of larvae of Trichoplusia ni and Anticarsia gemmatalis to intrahemocoelic injections of conidia and blastospores of Nomuraea rileyi

The LD₅₀ for larvae of Trichoplusia ni injected with blastospores of Nomuraea rileyi was 4.30 ± 1.16 hyphal bodies/larva; the LD₅₀ for injected conidia was ca. 25,000 conidia/larva. The dose-mortality regression line for blastospores was Y = 4.6504 + 0.5487 X. Larval mortalities of Anticarsia gemmatalis and T. ni at 100 blastospores/larva were 0.4 ± 0.5% and 96.7 ± 1.9%, respectively. At a dosage of 25,000 conidia/larva, larval mortalities for A. gemmatalis and T. ni were 0.4 ± 0.5% and 43.1 ± 8.7%, respectively. Thus, larvae of A. gemmatalis were > 100 times and >200 times more resistant to injected conidia and blastospores, respectively, than were larvae of T. ni. Resistance of A. gemmatalis to N. rileyi may not be solely at the integumental barrier, as is often believed, but may also be a function of an internal physiological response.     

樟芝的药用保健价值及开发应用(综述)

樟芝是一种原产于台湾的药用真菌,具有解毒抗癌、保肝强心、提高免疫力等功效。本文介绍樟芝的生物学特性、主要化学成分及药用保健价值,并对今后樟芝的开发应用提出建议。     

Phosphorus nutrition-mediated effects of arbuscular mycorrhiza on leaf morphology and carbon allocation in perennial ryegrass

The aim of this work was to disentangle phosphorus status-dependent and -independent effects of arbuscular mycorrhizal fungus (AMF) on leaf morphology and carbon allocation in perennial ryegrass (Lolium perenne). To this end, we assessed the P-response function of morphological components in mycorrhizal and nonmycorrhizal plants of similar size. AMF (Glomus hoi) stimulated relative P-uptake rate, decreased leaf mass per area (LMA), and increased shoot mass ratio at low P supply. Lower LMA was caused by both decreased tissue density and thickness. Variation in tissue density was almost entirely caused by variations in soluble C, while that in thickness involved structural changes. All effects of AMF were indistinguishable from those mediated by increases in relative P-uptake rate through higher P-supply rates. Thus the relationships between relative P-uptake rate, leaf morphology and C allocation were identical in mycorrhizal and nonmycorrhizal plants. No evidence was found for AMF effects not mediated by changes in plant P status.     

土壤真菌Curvularia affinis HS-FG-196抗肿瘤化学成分的再研究

为对土壤真菌Curvularia affinis HS-FG-196的次级代谢产物及其体外抗肿瘤活性进行进一步研究。实验采用大孔吸附树脂HP-20树脂柱、硅胶柱、凝胶LH-20柱及半制备高效液相色谱柱从Curvularia affinis HS-FG-196的发酵培养物中分离得到六个单体化合物(1～6)。利用~1H NMR、¹³C NMR、~1H-~1H COSY、HMQC、HMBC、IR、UV和MS等波谱分析方法对其进行了结构鉴定,分别是:pyrenocine S (1)、pyrenocine B (2)、pyrenocine E (3)、pyrenocine I (4)、pyrenochaetic acid B (5)和pyrenochaetic acid C (6),其中化合物1是新化合物。对所得单体化合物进行了体外抗肿瘤活性测试,结果显示化合物1、2、3对肿瘤细胞A549、HCT-116、ACHN、K562和HepG2表现出较强的活性。     

前体、诱导子及抑制剂对细胞培养生产紫杉醇的调节作用

研究了前体、诱导子和抑制剂对中国红豆杉细胞培养生产紫杉醇的影响。结果表明 ,它们之间的协同作用对提高紫杉醇的产量有显著影响。其中向培养基中加入 30mg/L 3 甲基 2 丁烯 1 醇 ,2mmol/L苯甲酸钠 ,10mg/L氯化氯胆碱 (CCC) ,10 0 μmol/L茉莉酸甲酯 (MJ) ,0 1mmol/L丝氨酸 (Ser)可以使紫杉醇含量增加 1141 1%。     

Molecular cloning and characterization of a cDNA encoding ent-cassa-12,15-diene synthase, a putative diterpenoid phytoalexin biosynthetic enzyme, from suspension-cultured rice cells treated with a chitin elicitor

We have isolated and characterized a cDNA encoding a novel diterpene cyclase, OsDTC1, from suspension-cultured rice cells treated with a chitin elicitor. OsDTC1 functions as ent-cassa-12,15-diene synthase, which is considered to play a key role in the biosynthesis of (-)-phytocassanes recently isolated as rice diterpenoid phytoalexins. The expression of OsDTC1 mRNA was also confirmed in ultraviolet (UV)-irradiated rice leaves. In addition, we identified ent-cassa-12,15-diene, a putative diterpene hydrocarbon precursor of (-)-phytocassanes, as an endogenous compound in the chitin-elicited suspension-cultured rice cells and the UV-irradiated rice leaves. The OsDTC1 cDNA isolated here will be a useful tool to investigate the regulatory mechanisms of the biosynthesis of (-)-phytocassanes in rice.     

墨西哥仙人掌植物内生真菌的研究Ⅰ.内生真菌分离及其抗菌活性筛选

从一种墨西哥仙人掌[Opuntiamicrodasys(Lehm .)Pfeiff]的肉质茎中分离获得31株内生真菌,经形态观察分类鉴定为3个目、3个科、14个属。同时选择2 2种病原微生物作为指示菌进行抑菌试验,研究其抗菌活性。结果表明:3株仙人掌内生真菌分别对细菌、植物病原真菌和皮肤致病真菌多种病原微生物有较为明显的抑制生长作用。     

Host selection and survival of the parasitoidEncarsia formosa on greenhouse whitefly,Trialeurodes vaporariorum, in the presence of hosts infected with the fungusAschersonia aleyrodis

Successful control of greenhouse whitefly may be achieved by complementary activity of the parasitoidEncarsia formosa and the fungusAschersonia aleyrodis. One way to obtain an additive mortality effect of both entomopathogen and parasitoid would be achieved by the selection of healthy hosts by the parasitoid and rejection of fungus-infected hosts. Third and fourth instar larvae ofTrialeurodes vaporariorum which had been treated with a spore suspension ofA. aleyrodis 0, 4, 7, 10 or 14 days beforehand, were presented to female parasitoids. The parasitoids adopted the oviposition posture on untreated hosts as well as on treated hosts, irrespective of the different stages of infection in the hosts. However, significantly more hosts were parasitized byE. formosa in the control treatment than in the fungal treatment. The parasitoids offered treated hosts, showed rejection behaviour after probing on hosts showing detectable signs of infection (containing hyphal bodies or mycelium in the haemolymph). For instance, when hosts were offered seven days after spore treatment, the parasitoids showed an oviposition posture on a total of 83 (95.4%) out of 87 infected larvae, but laid only 4 eggs (4.6%). In contrast, on 48 (94.1%) out of 51 noninfected (or showing no detectable signs of infection) hosts an oviposition posture was adopted and 40 eggs (78.4%) were found after dissection. When infected hosts were encountered the oviposition posture lasted less than 1′40″ while rejection of non-infected hosts occurred after more than 1′40″. Other experiments were carried out offering treated hosts for 24 h to the parasitoids. The hosts were dissected afterwards. Again, significantly more eggs were laid in the non-infected hosts. When hosts were parasitized shortly after fungal spore treatment they were colonized by the fungus and the parasitoids did not develop. Transmission of the entomopathogen after probing infected hosts was observed to a limited extent. In conclusion,A. aleyrodis andE. formosa can be used together in a glasshouse situation. The parasitoid will be most effective when introduced more than seven days after application ofA. aleyrodis, because from that time onwards it is able to detect and reject fungus-infected hosts.