Contamination of malt barley and wheat by Fusarium graminearum and Fusarium culmorum from the crop years 2001-2003 in eastern Croatia

This study investigated infection levels with Fusarium graminearum and Fusarium culmorum in malt barley and wheat in eastern Croatia. The contamination was surveyed over three consecutive crop years (2001–2003) on five locations for barley and three wheat cultivating locations. F. graminearum loads reached levels of potentially serious threat for the commercial production of malting raw materials in both cereals (up to 29.1%). On the other hand, the mean percentage of kernels infected with F. culmorum was low to medium (up to 6.1%). The fungal invasions for years and locations were affected by meteorologic and other environmental factors and the pattern seemed to be consistent with species-specific optimal conditions reported by other authors.     

Field Evaluation of Fungal Competitors of Fusarium culmorum and F. graminearum, Causal Agents of Ear Blight of Winter Wheat, for the Control of Mycotoxin Production in Grain

Thirty-seven antagonists, from a collection of 113 pre-screened microorganisms, were tested in field experiments on winter wheat for their ability to control ear blight and production of mycotoxins, particularly deoxynivalenol (DON), in grain by Fusarium culmorum and F. graminearum. Ears were spray-inoculated during anthesis with spore suspensions, first of test fungi and then of the pathogen. Isolates of F. equiseti were the most effective treatments. A strain of F. equiseti (G9) decreased DON consistently on wheat inoculated with F. culmorum, compared with the control, often by more than 70%. It performed well under severe disease pressure (F. culmorum at 10⁵ conidia mL^-1) and similarly to a standard fungicide, tebuconazole. Percentages of diseased grains and amounts of DON corresponded well. Small quantities of nivalenol (NIV) occurred in grain samples after treatment with some F. equiseti strains. On wheat inoculated with F. graminearum, F. equisti G2 decreased the percentage diseased grains by 92% and DON by 94%. One strain of F. equiseti (G2) was found to produce small amounts of NIV in pure culture.     

Lactones 20 []: Biohydroxylation of saturated bicyclic γ-lactones with the substituted cyclohexane system

Three bicyclic saturated γ-lactones with various numbers of methyl groups at the cyclohexane ring were transformed into the corresponding hydroxylactones. The most effective biohydroxylations were performed by means of cultures Fusarium culmorum and Absidia cylindrospora. Biotransformations of lactones 4a and b afforded the hydroxylactones with the secondary hydroxy groups (5a and b), whereas the hydroxy group introduced into the lactone 4c turned out to be tertiary giving the product 5c.     

Potential of fungal antagonists for biocontrol of Fusarium spp. in wheat and maize through competition in crop debris

Pathogenic Fusarium spp. cause head blight in wheat or ear rot in maize leading to yield losses and also a reduction in quality due to mycotoxin contamination of the grain. Infected crop residues are the main inoculum source for epidemics. Saprophytic fungi, obtained from cereal tissues or necrotic tissues of other crops, were screened for their ability to colonise wheat straw and maize stalks and to suppress sporulation of pathogenic Fusarium spp. Results of bio-assays conducted under controlled conditions were variable among Fusarium spp. and host substrates for most antagonists tested, such as yeasts, Trichoderma spp. and non-pathogenic Fusarium spp. Isolates of Clonostachys rosea consistently suppressed sporulation of F. culmorum and F. graminearum on wheat straw, and of F. culmorum, F. graminearum, F. proliferatum and F. verticillioides on maize stalks. Isolates of C. rosea, C. cladosporioides and F. equiseti were applied to pieces of maize stalks or flowering ears in preliminary experiments conducted under field conditions. The colonisation of stalk pieces by pathogenic Fusarium spp. was assessed after 9 months. Colonisation of stalk pieces by pathogenic Fusarium spp. was significantly reduced at several sampling dates. However, results obtained with the antagonists were not consistent for all sampling dates and between experiments.     

An adaptive evolutionary shift in Fusarium head blight pathogen populations is driving the rapid spread of more toxigenic Fusarium graminearum in North America

Analysis of Fusarium head blight (FHB) pathogen diversity revealed that 3ADON producing Fusarium graminearum are prevalent in North America and identified significant population structure associated with trichothecene chemotype differences (F(ST)>0.285; P<0.001). In addition, we identified a trichothecene chemotype cline in Canada and documented a recent and significant shift in FHB pathogen composition by demonstrating that the 3ADON chemotype frequency in western Canada increased more than 14-fold between 1998 and 2004. On average, isolates from 3ADON populations produced significantly (P<0.05) more trichothecene and had significantly (P<0.005) higher fecundity and growth rates than isolates from the 15ADON population. These results indicate that selection is driving the rapid spread of an introduced pathogen population that is more toxigenic and potentially more vigorous. The discovery of this previously unrecognized pathogen diversity has significant implications for food safety and cereal production in North America.     

两种昆虫激素对鹿儿岛被毛孢表观形态的影响

昆虫激素不仅能调控昆虫的生长发育,而且也是昆虫免疫系统的重要调节因子,因此当虫生真菌入侵昆虫寄主体腔并定殖时可能会受其影响。但定殖过程中虫生真菌与昆虫激素之间的直接作用关系尚不清楚。本研究利用不同浓度的蜕皮激素(20E)和保幼激素(JH)模拟鳞翅目昆虫家蚕体内的主要激素水平,对虫生真菌鹿儿岛被毛孢Hirsutella satumaensis进行培养,观察其表观形态特征的变化。结果表明,两种昆虫激素对鹿儿岛被毛孢的表观形态均有不同程度的影响。添加20E和JH培养后,鹿儿岛被毛孢菌落直径和菌丝生物量的变化差异不大;孢子的萌发率稍有下降;而菌落产生的色素和产孢量与对照组相比则呈现显著性变化。菌落色素圈和分生孢子的粘液厚度会随两种激素浓度的增加而增大,而产孢量随激素浓度增加呈先增加后降低的趋势,这说明鹿儿岛被毛孢定殖昆虫血体腔的过程中两种昆虫激素会抑制真菌的生长,而虫生真菌会适应性地做出应答反应,这对于进一步理解虫生真菌在昆虫血体腔中的定殖机理有重要意义。     

An adaptive evolutionary shift in Fusarium head blight pathogen populations is driving the rapid spread of more toxigenic Fusarium graminearum in North America.

Analysis of Fusarium head blight (FHB) pathogen diversity revealed that 3ADON producing Fusarium graminearum are prevalent in North America and identified significant population structure associated with trichothecene chemotype differences (F(ST)>0.285; P<0.001). In addition, we identified a trichothecene chemotype cline in Canada and documented a recent and significant shift in FHB pathogen composition by demonstrating that the 3ADON chemotype frequency in western Canada increased more than 14-fold between 1998 and 2004. On average, isolates from 3ADON populations produced significantly (P<0.05) more trichothecene and had significantly (P<0.005) higher fecundity and growth rates than isolates from the 15ADON population. These results indicate that selection is driving the rapid spread of an introduced pathogen population that is more toxigenic and potentially more vigorous. The discovery of this previously unrecognized pathogen diversity has significant implications for food safety and cereal production in North America.     

豌豆茎基腐病病原菌分离鉴定及其对杀菌剂的敏感性测定

豌豆(Pisum sativum)是我国重要的豆类经济作物, 病害对豌豆生产造成重大经济损失。通过形态学观察、分子鉴定以及致病性测定, 最终确定引起豌豆茎基腐病的3种病原菌分别为尖孢镰刀菌(Fusarium oxysporum)、芸苔链格孢菌(Alternaria brassicae)和格氏镰刀菌(F. grosmichelii), 优势菌株为尖孢镰刀菌, 分离率为53.6%。室内毒力测定结果表明, 5种供试杀菌剂对3种病原菌的菌丝生长均有抑制作用, 其中咯菌腈和戊唑醇的抑菌效果最好。研究结果为豌豆茎基腐病的防治提供了科学依据。     

Expression kinetics and plasmid stability of recombinant E. coli encoding urease-derived peptide with bioinsecticide activity

The nucleotide sequence encoding for an insecticidal peptide derived from the Canavalia ensiformis urease gene jbureII (AF 468788), was cloned and expressed in the pET101/Escherichia coli expression system. Bacterial cultivation in shaker with lactose as inducer produced 1.26 μg of recombinant peptide/mg protein, after 8 h of growth. The plasmid stability and the expression of the recombinant peptide were studied in bioreactor. Expression of the recombinant peptide was strongly affected by pH of cultures, with a decrease of more than 50% when acidification was freely allowed. Likewise, peptide production and plasmid stability were shown to be affected by aeration and agitation speed, both decreasing for higher values of oxygen mass transfer rates. Despite these difficulties, in bioreactor cultures carried out with controlled pH, low oxygen mass transfer rates and using lactose as inducer, we were able to achieve a total peptide production of 7.14 μg/mg protein, which represents approximately 2% of total cell protein. Bioassays were carried out using the purified peptide on insect models. The peptide fed to Dysdercus peruvianus nymphs produced 100% mortality after 11 days, deaths starting with a lag phase of 3–4 days, confirming that the bioreactor-produced peptide retained its biological activity.     

Effect of photoperiod on the size–temperature relationship in a pentatomid bug, Dolycoris baccarum

(1) The effects of photoperiod and temperature on nymphal growth, development and adult size in a pentatomid bug, Dolycoris baccarum, were examined. (2) The temperature–size relationship was not stable but was highly affected by the photoperiod, and showed a geographical variation. (3) There were variations also in the developmental period and the growth rate. (4) The responses to temperature and photoperiod can explain the seasonal and geographical adaptations of the insect, and thus are considered to be important seasonal adaptations in D. baccarum.     

Site-directed mutagenesis reveals the importance of disulfide bridges and aromatic residues for structure and proliferative activity of human interleukin-4.

The presence of a glycan of the same molecular size as the lipid linked precursor oligosaccharide (Glc₃Man₉GlcNAc₂) of the N-linked protein glycosylation pathway in mammalian cells has been detected in a glycolipid fraction of cultured Drosophila melanogaster cells. Oligosaccharide sequencing studies were consistent with the existence of a glucosylated high mannose containing structure, which may be the common precursor for N-linked protein glycosylation in insect cells.     

尖孢镰刀菌亚麻专化型Folprp4基因参与调控菌丝生长和分生孢子发生

目的: 通过对尖孢镰刀菌中Folprp4基因的鉴定,揭示其在尖孢镰刀菌中的功能及致病相关性。方法: 基于同源重组原理,根据测定出的Folprp4基因序列,应用Split-Marker重组技术构建含有潮霉素抗性基因(hph)的基因缺失盒。将基因缺失盒经PEG介导转化到野生型原生质体中,在含有潮霉素B的TCC培养基上筛选转化子,通过PCR正负筛查获得Folprp4基因缺失突变株(ΔFolprp4)。构建含有Folprp4基因的载体pZDH1,并将其转化到敲除突变体中进行互补测验。结果: 与野生型(hm)和异位插入突变体(ecFolprp4)相比,敲除突变体菌丝生长受到严重阻碍,当野生型和异位插入突变体长满整个平板时,敲除突变体菌落呈小点状。敲除突变体的另一个显著变化是ΔFolprp4的分生孢子产量显著下降。侵染实验表明,ΔFolprp4对亚麻幼苗的毒力显著降低。互补实验表明,该互补载体的回复子(Folprp4-C)在菌落形态、生长速率、分生孢子产量和毒力方面均恢复到了野生型菌株。结论: Folprp4基因与尖孢镰刀菌的菌丝生长、分生孢子发生和致病性有关。     

Stable expression of insect GABA receptors in insect cell lines promoters for efficient expression of Drosophila and mosquito Rdl GABA receptors in stably transformed mosquito cell lines

We are interested in establishing stably transformed insect cell lines efficiently expressing the insect γ-aminobutyric acid (GABA) receptor subunit gene Resistance to dieldrin or Rdl. In order to facilitate this we utilized a system based on stable transformation of Aedes albopictus mosquito cell lines using the dihydrofolate reductase (dhfr) gene as a selectable marker. Here we report the production of stable mosquito cell lines carrying high copy numbers of Rdl genes from both Drosophila and Aedes aegypti mosquitoes and the subsequent high efficiency expression of functional GABA gated chloride ion channels. We also used this system to compare the activity of a range of immediate early baculovirus promoters in mosquito cell culture and demonstrate that IE1 promoter constructs work efficiently across insect species. Results are discussed in relation to the potential use of these constructs in the genetic transformation of non-Drosophilid insects.     

Characterization of yeastolate fractions that promote insect cell growth and recombinant protein production

Yeastolate is effective in promoting growth of insect cell and enhancing production of recombinant protein, thus it is a key component in formulating serum-free medium for insect cell culture. However, yeastolate is a complex mixture and identification of the constituents responsible for cell growth promotion has not yet been achieved. This study used sequential ethanol precipitation to fractionate yeastolate ultrafiltrate (YUF) into six fractions (F1–F6). Fractions were characterized and evaluated for their growth promoting activities. Fraction F1 was obtained by 65% ethanol precipitation. When supplemented to IPL-41 medium at a concentration of 1 g L⁻¹, fraction F1 showed 71% Sf-9 cell growth improvement and 22% β-galactosidase production enhancement over YUF (at 1 g L⁻¹ in IPL-41 medium). However, the superiority of F1 over YUF on promoting cell growth gradually diminished as its concentration in IPL-41 medium increased. At 4 g L⁻¹, the relative activity of F1 was 93% whereas YUF was 100% at the same concentration. At 1 g L⁻¹, four other fractions (F2–F5) precipitated with higher ethanol concentrations and F6, the final supernatant, showed growth promoting activities ranging from 32 to 80% as compared to YUF (100%). Interestingly, a synergistic effect on promoting cell growth was observed when F6 was supplemented in IPL-41 medium in presence of high concentrations of F1 (>3 g L⁻¹). The results suggest that ethanol precipitation was a practical method to fractionate growth-promoting components from YUF, but more than one components contributed to the optimum growth of Sf-9 cells. Further fractionation, isolation and identification of individual active components would be needed to better understand the role of these components on the cell metabolism.     

Effect of culture conditions on lipid and gamma-linolenic acid production by mucoraceous fungi

The effect of various culture conditions on growth, lipid production and fatty acid composition in Mucor rouxii and Mucor sp.1b were studied. Total lipid production was higher in media containing potassium nitrate for both the cultures (30%) and cultures grown on plant seed oil produced more than 44% lipid. Among the carbon sources tested, γ-linolenic acid (GLA) production was maximal in cultures grown on glucose. The major fatty acids produced by these two cultures were palmitic, stearic and oleic acids. Levels of GLA in M. rouxii and M. sp.1b was in the range of 3–17% under different culture conditions. Lactose was a poor promoter for biomass and lipid production in both cultures. No GLA was found in fungal cultures grown on sesame oil. The optimal conditions for the production of GLA was standardised in these cultures.     

Bioactivity-guided fractionation for anti-inflammatory and analgesic properties and constituents of Xanthium strumarium L.

The aim of this study was to fractionate an extract of Xanthium strumarium L. (EXS) and to investigate the anti-inflammatory and analgesic properties of the extract and its fractions. The ethanol extract of X. strumarium (EXS) was fractionated on the basis of polarity. Among the different fractions, the n-butanol fraction showed the highest anti-inflammatory activity in the croton-oil-induced ear edema test and furthermore reduced the number of writhings induced by acetic acid in mice in a dose-dependent manner. This indicates that the n-butanol fraction of X. strumarium possesses potent analgesic effects which are likely to be mediated by its anti-inflammatory activity. Bioassay-guided fractionation of EXS led to the isolation and identification of ten caffeoylquinic acids and three heterocyclics by HPLC–DAD–MSⁿ from the active n-butanol fraction, implying that the active compounds are polar in nature. The isolated caffeoylquinic acids could partially explain the antinociceptive effect of X. strumarium polar extract.     

Enhancement of production of cloned glucoamylase under conditions of low aeration from recombinant yeast using a SUC2 promoter

The effect of aeration rate on the production of cloned glucoamylase in a recombinant yeast was investigated. This system consisted of Saccharomyces cerevisiae transformed with the 2 μ-based plasmid YEpSUCSTA which contains the SUC2 promoter, the STA signal sequence, and the STA structural gene. In contrast to typical yeast expression reports, high production of cloned glucoamylase was achieved at low aeration level (0·3 vvm). The recombinant yeast grown at 0·3 vvm aeration produced more glucoamylase (0·94 units/ml) than when grown at 0·0 vvm, 0·6 vvm, or 0·9 vvm (9·4, 1·4, and 3·1 times more, respectively). A high dissolved oxygen level early in the cultivation was important for cell growth and a low dissolved oxygen level during the production stage was important for glucoamylase production. In large scale processes for the production of recombinant proteins, the maintenance of aeration and dissolved oxygen at high levels is difficult and expensive. In this work, we have evaluated the coordination of oxygen level with growth and protein production and developed optimal conditions. Since a low aeration rate was optimal, our results demonstrate that the method described at the laboratory scale should be successfully applied at an industrial scale.     

闽东南地区马尾松古树对气候变化和虫灾的生态弹性

马尾松是我国南方地区广泛分布的先锋造林树种。在全球变暖、气候干旱化和虫灾频发的趋势下,研究马尾松对环境干扰的生态弹性对森林管理有重要意义。本文对福建省仙游县百松村的马尾松古树进行树木年轮样品采集,建立区域首个马尾松树轮宽度标准年表(1865—2014年)。结果表明: 当年7—9月低相对湿度和5—9月极端高温是树木生长的主要限制因素。根据树轮极端窄年确定1869、1889、1986、1991和1993是极端事件年。时序叠加分析发现,极端事件发生前两年的持续低值加剧了极端事件的影响。干旱年份更容易引发虫灾。1889年是受虫灾影响最严重的年份,1986和1991年受到虫灾和干旱气候的双重影响,其余极端年主要受干旱气候的影响。树木对虫灾的抵抗力弱于对干旱事件的抵抗力;除1991年外,树木对虫灾的相对弹性力高于对干旱事件的相对弹性力。1889年的相对弹性力最高,1991年受到连续极端事件的影响,相对弹性力最低。2000年以来研究区干旱化趋势加强,马尾松古树遭受干旱和虫灾的干扰加强,部分树木死亡。     

昆虫肠道木霉及其对芒果炭疽病菌拮抗作用

为获得优良生防木霉菌株,本研究以昆虫肠道为样本,从中分离鉴定木霉菌株,并以芒果炭疽病菌盘长孢状刺盘孢为靶标菌,通过对峙培养、挥发性物质和非挥发性物质筛选拮抗效果最优的木霉菌株,测定其孢子悬浮液对芒果炭疽病的室内防效研究.结果 显示,从105份昆虫肠道中共分离获得10株木霉,通过形态学特征和Tef1-Rpb2双基因联合建...     

精胺合成酶MrSPS参与调控罗伯茨绿僵菌的生长发育、抗逆和致病力

本研究以罗伯茨绿僵菌Metarhizium robertsii为研究对象,针对鉴定出的精胺合成酶基因(MAA_02088, Mrsps),利用农杆菌介导的同源重组方法获得Mrsps敲除株ΔMrsps。与野生型相比,ΔMrsps营养生长和产孢能力下降,对氯化钠和紫外照射耐受性增强。大蜡螟幼虫毒力分析表明,浸渍和注射两种情况下ΔMrsps致病力降低,半致死时间(LT₅₀：6.71和4.75 d)比野生型(LT₅₀：5.17和4.19 d)显著增加。Mrsps敲除后不影响附着胞形成率和蝉翅穿透能力,但会显著下调昆虫血腔定殖相关基因的表达量。这些结果说明精胺合成酶MrSPS参与调控罗伯茨绿僵菌的生长发育、外界胁迫应答和致病力。