Impact of tillage on the incidence ofFusarium spp. in soil

The influence of several long-term conventional and conservation tillage treatments on the incidence and the diversity ofFusarium spp. in soil was studied. Soil samples were randomly collected from naturally contaminated field trials and Fusarium species were isolated by using the dilution plate method. The identification of the species was done by direct microscopic observation onFusarium-specific media. The isolation frequency ofFusarium species and the total number of colony forming units was affected by the sampling year and the cultivated crop and showed significant differences between the tillage treatments. Moldboard plough-treatments resulted in a lower diversity of Fusarium species than the chisel plough and rotary tiller treatments. Besides the tillage system the tillage depth also appeared to affect theFusarium populations. The deeper the tillage the lower was the number of isolatedFusarium spp. TwentyFusarium species were identified over both years of investigation. In conservation tillage plots a higher diversity ofFusarium species was found than in the moldboard plough-based tillage plots. A correlation betweenFusarium species producing the mycotoxin deoxynivalenol (DON) isolated from soil and the DON-content of grain could not be observed. However, these investigations indicate that conservation soil tillage results in conditions which increase the incidence ofFusarium species in soil.     

A survey of the natural occurrence ofFusarium toxins in wheat grown ina southwestern area of Germany

Wheat for feed use (84 samples) was collected after harvest from 79 farms in a southwestern part of Germany (Baden-Wuerttemberg). The 1987 crop year was characterized by heavy rainfall in the summer months. The internal mycoflora of wheat samples was primarily fusaria, and storage fungi were rarely present. TheFusarium toxins, zearalenone (ZON), - and -zearalenol (,-ZOL), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), nivalenol (NIV), T-2 Toxin (T-2), HT-2 toxin (HT-2) and diacetoxyscirpenol (DAS) were analysed by gas chromatography with mass selective detection (detection limit: 1–3 µg/kg). Each of the samples contained at least one of theFusarium toxins examined except DAS. DON, ZON, 3-AcDON, NIV, T-2, HT-2 and -ZOL were detected in 96%, 80%, 59%, 26%, 26%, 7% and 5% of samples, with an average of 1632, 178, 7, 9, 82, 10 and 23 µg/kg, and a maximum of 20538, 8036, 18, 32, 249, 20 and 71 µg/kg, respectively. -ZOL (12 µg/kg) was found in one sample with -ZOL (71 µg/kg). One, two, three, four, five and sixFusarium toxins were detected in 6%, 27%, 37%, 23%, 4%, and 4% of total samples, respectively. The most frequent combination was that of ZON with DON and 3-AcDON, followed by the combinations ZON/DON and ZON/DON/3-AcDON/NIV in 22, 20, and 11% of total samples, respectively.Abbreviations 3-AcDON 3-Acetyldeoxynivalenol - DAS Diacetoxyscirpenol - DON Deoxynivalenol - HT-2 HT-2 toxin - NIV Nivalenol - T-2 T-2 toxin - -ZOL -Zearalenol - -ZOL -Zearalenol - ZON Zearalenone     

Selection for resistance to filtrates of Fusarium spp. in embryogenic cell suspension culture of Medicago sativa L.

A highly embryogenic cell suspension of alfalfa derived from a genotype sensitive to Fusarium oxysporum was successfully used for selection in vitro for resistance to culture filtrates of F. oxysporum, F. solani and F. avenaceum. Fifty two stable resistant cell lines were obtained and 500 plants regenerated from them. Among the 167 regenerants tested under glass there were 12–20% more plants with increased resistance to pathogens than in the group of plants regenerated from a control cell line. It was also found that the cell suspension cultures derived from genotypes of alfalfa with increased resistance to Fusarium spp. better tolerated filtrates of the pathogen. The results of a comparison of virulence of individual isolates of several species of Fusarium with toxicity of their filtrates to plants in vivo and in cell cultures were not unequivocal.     

Survey ofFusarium species in an arid environment of Bahrain

The prevalence and distribution of soil-inhabitingFusarium species in the soil of vegetable crops grown under custom-made plastic tunnels were studied at three geographical locations on the island of Bahrain. Six species ofFusarium representing a total of 1154 isolates were isolated on modified Komada medium. All species reported in this survey are recorded for the first time from the hot, arid desert of Bahrain.Fusarium solani andF. oxysporum were among the most frequently isolated fungi in all locations and crops.     

粮食上木霉菌的分离鉴定及其生防效果

【背景】粮食在生长和收储期极易受到病原真菌或产毒真菌的污染,造成严重的损失。众多实践证明木霉属(Trichoderma)可以有效防治植物病原真菌。【目的】鉴定和筛选能有效抑制粮食常见危害真菌的木霉生防菌株,开发生防菌剂,保障粮食生产安全。【方法】从粮食上分离筛选出35株木霉,通过多基因系统发育分析和形态学观察方法进行菌种鉴定,利用平板对峙试验筛选出对粮食常见危害真菌有抑制作用的菌株。【结果】35株木霉分属于8个种,分别为非洲哈茨木霉(Trichodermaafroharzianum)、类棘孢木霉(Trichodermaasperelloides)、 Trichoderma amoenum、近深绿木霉(Trichoderma paratroviride)、Trichoderma obovatum、长枝木霉(Trichoderma longibrachiatum)、东方木霉(Trichodermaorientale)和深绿木霉(Trichodermaatroviride)。对峙试验结果表明,这8种木霉对于粮食上分离到的10种危害真菌均具有较好的抑制效果。非洲哈茨木霉(T.afroharzi...     

Occurrence ofDinophysis spp. and toxic shellfish in the Northern Adriatic

The dynamics of the toxicity of the musselMytilus galloprovincialis was compared between two different shellfish farms, 5 km apart, but using the same cultivation technique. The main differences concerned the freshwater influx and the open aspect to the Gulf of Trieste. It is suggested that a deep closed bay and abundant fresh water inflow are the two main conditions for the low toxicity levels in mussels and for shorter periods of danger. A detailed study of the phytoplankton samples revealed the presence of eight species ofDinophysis in the area of both shellfish farms. During the period of the DSP outbreak in Slovenia (autumn and winter 1989).D. fortii andD. acuminata were the most frequentDinophysis species. There was a high positive correlation between the onset of mussel toxicity and the appearance ofDinophysis spp.     

A biological assay for the detection of Myrothecium spp. produced macrocyclic trichothecenes

A rapid, inexpensive bioassay to detect Myrothecium spp.-produced macrocyclic trichothecenes was developed. Media containing Myrothecium isolates were inoculated with Chlorella vulgaris, Ustilago maydis and Trichoderma viride. Based on width of the inhibition zone, isolates could be classified as highly toxigenic, non-toxigenic and intermediate. Whereas, C. vulgaris and U. maydis showed significant differences in their response to toxigenic and non-toxigenic isolates, T. viride did not. Production of roridins and verrucarins by the toxigenic isolates (by bioassay) was confirmed by thin layer chromatography and high performance liquid chromatography. This bioassay system, combined with confirmation chemical analyses, increases our ability to detect toxigenic fungal isolates.     

Level ofFusarium infection in wheat spikelets related to location and number of inoculated spores

The flowering time is the most susceptible period for primary infection of wheat heads byFusarium spp. During this period spores can be deposited into the opened wheat florets where they may later cause infections. We quantitatively explored the relationship between variables related to the flowering process and the infection level byFusarium graminearum in single spikelets. We imitated open (chasmogamous) and closed (cleistogamous) flowering by injecting well-defined amounts of spores into and between wheat florets. Applying the spores between the florets resulted in weaker disease symptoms and significantly lower amounts ofFusarium mycotoxins. With larger numbers of spores, the disease symptoms became more pronounced and the mycotoxin amounts per spikelet increased significantly. Our results indicate that the probability of primary infection is approximately proportional to the number of spores reaching the open florets during the flowering process. The breeding of wheat lines which flower partially or completely cleistogamously might reduce theFusarium susceptibility in wheat.     

Using the Tools at Hand: Manual Laterality and Elementary Technology in Cebus spp. and Pan spp.

Cebus and Pan appear to be a remarkable example of evolutionary convergence in behavioral ecology. We examine their apparently analogous solutions to problems posed by laterality of hand function and elementary technology. We scrutinize appropriate published data in a meta-analysis, focusing on Cebus apella and C. capucinus and on Pan paniscus and P. troglodytes. We compare behavioral data in terms of captive versus wild, and tool use versus non-tool use, but notable gaps exist in the data, especially for bonobos. Cebus and Pan spp. are equivalent tool users in captivity, but chimpanzees are notably more extensively so in nature. For hand preference, captive bonobos and wild and captive chimpanzees show ambipreference for non-tool-use patterns. For both Cebus spp. and Pan spp., there is a tendency for individuals to be committed exclusively to one hand or the other for tool use. The data for laterality of hand function fit consistently into the five-level model proposed by McGrew and Marchant (1996).     

Improved Technique for Rapid and Non-Destructive In Vitro Differentiation between Resistant and Susceptible Banana Clones of Fusarium Oxysporum f. sp. Cubense

Culture filtrates of Fusarium oxysporum f. sp. cubense were applied to field-grown banana leaves of susceptible and resistant clones. The difference in leaf lesions, measured after 48 h, varied from 13 to 51 mm2 depending on the composition of the growth medium.     

BOX-PCR is an Adequate Tool for Typing <Emphasis Type="Italic">Aeromonas</Emphasis> spp.

PCR-based methods of fingerprinting take advantage of the presence of repetitive sequences that are interspersed throughout the genome of diverse bacterial species. They include the repetitive extragenic palindromic (REP) sequence, the enterobacterial repetitive intergenic consensus sequence (ERIC) and the 154-bp BOX element. The combination of the three methods is used for fine discrimination of strains and is designated as rep-polymerase chain reaction (PCR). REP-PCR and ERIC-PCR have been shown to be useful for typing Aeromonas strains. To our knowledge, rep-PCR fingerprinting method using the BOXA1R primer has never been tested on aeromonads. In this study, the BOX-PCR fingerprinting technique was evaluated for the discrimination of strains of some Aeromonas species. All strains were typeable and the majority showed unique banding patterns. Four strains from culture collections were used to investigate the reproducibility of the method. According to our results, BOX-PCR fingerprinting is applicable for typing of Aeromonas strains and can be considered as a useful complementary tool for epidemiological studies of members of this genus.     

Screening for microbial trehalases: extracellular trehalases produced byFusarium species

Two hundred microorganisms comprising actinomycetes, bacteria, fungi and yeasts were screened for extracellular trehalases by their growth on trehalose in solid and liquid culture.Candida albicans, Gelasinospora retispora and four isolates belonging to the genusFusarium produced extracellular trehalases. The production of trehalase by theFusarium spp. was influenced by the nutrient composition of the medium and the carbon source; of the substrates examined starch produced the highest enzyme titre. Trehalase was an inducible enzyme and was repressed when theFusarium spp. were grown on glucose. The properties of the trehalases from two of theFusarium spp. (isolates MU-105 and TR-8) were typical of non-regulatory trehalases. Activity of several α-glucosidases, an amylase, an invertase and a cellobiase was also demonstrated when the two isolates were grown on trehalose.     

Cellulolytic activity of four Fusarium spp.

Fusarium lini, F. lycopersici, F. pallidoroseum and F. semitectum grown in shake flasks produced, respectively, 0.19, 0.33, 0.13 and 0.09 units filter-paper cellulase/ml. Trichoderma reesei, in comparison, produced 0.8 U/ml.The authors are with Defence Food Research Laboratory, Mysore-570 011, India.     

Hyperparasitism by Mesochorus spp. (Hymenoptera: Ichneumonidae) in Peristenus sp. (Hymenoptera: Braconidae) and development of PCR primers for hyperparasitoid detection

Peristenus sp. pupae collected from Lygus spp. nymphs in 2001 and 2002 were over-wintered in the laboratory. In both years, more than 30% of adults emerging from over-wintering pupae were identified as ichneumonid hyperparasitoids, Mesochorus curvulus Thomson and Meschorus sp. (Hymenoptera: Ichneumonidae). At the end of the over-wintering period, Peristenus sp. males emerged first followed by Peristenus sp. females and finally Mesochorus spp. The male:female ratio in emerging Peristenus sp. adults was skewed towards males. The Internal Transcribed Spacer (ITS) region and the cytochrome oxidase I (COI) gene from Mesochorus spp. were sequenced. ITS sequences were used to develop PCR primers to detect Mesochorus spp. hyperparasitism in the primary host, Lygus spp. PCR analysis of field-collected Lygus spp. nymphs gave similar estimates of Mesochorus spp. hyperparasitism to the rearing protocols (25–28%). Sequence analysis of COI and ITS regions and subsequent restriction endonuclease analysis of ITS PCR products from Mesochorus spp. indicate the presence of two genotypes in the population. The possibility that these two genotypes represent separate or cyrptic species is discussed.     

Virulence ofPythium spp. isolated from pond water

Pre-emergence damping-off tests indicate that Pythiumspp. from pond water can be divided into two categories: avirulent Pythium (P. diclinum, P. marsipium, P. middletonii, P. monospermum, P. pleroticum, P. undulatum)and weakly virulent Pythium (P. catenulatum, P. coloratum, P. dissotocum, P. papillatum, Pythium Group F, Pythium group HS, Pythium group P, Pythiumgroup T). Post-emergence damping-off tests indicate that the pythia tested can also be divided into three categories: avirulent Pythium (P. catenulatum, P. dissotocum, P. marsipium, P. monospermum, P, papillatum, P. pleroticum, P. undulatum, Pythium group F, Pythium group T),weakly virulent Pythium (P. coloratum, P. diclinum, P. middletonii, Pythiumgroup P and moderately virulent Pythium (Pythium group HS).     

Extracellular enzymatic activity of Malassezia spp. isolates

Extracellular enzymatic activity of different species of Malassezia spp was evaluated. Thirty-three isolates of animal origin (dogs and cats) and stock culture samples were studied. Twenty isolates of M. pachydermatis, 8 of M. furfur, 2 of M. sympodialis and M. globosa and one of M. restricta, M. obtusa and M. slooffiae were examined. The enzymatic activity was investigatedusing Api Zym system. The enzymatic patterns showed light differences. Esterase lipase, Phosphatase acid and Naphtol-AS-BI-phosphohydrolase were produced in significant amounts from most isolates excepted for M. restricta, confirming the limited enzymatic activity of this species. Data obtained from the other new species described after the revision of the genus, appear to be quite homogeneous. Dixon’s broth appeared to be a valid medium for the growth of all Malassezia spp. This revised version was published online in June 2006 with corrections to the Cover Date.     

Prevalence of Fusarium species of the Liseola section on selected Colombian animal feedstuffs and their ability to produce fumonisins

A total of 57 samples of feedstuffs commonly used for animal nutrition in Colombia (corn, soybean, sorghum, cottonseed meal, sunflower seed meal, wheat middlings and rice) were analyzed for Fusarium contamination. Fusarium fungi were identified at species level by means of conventional methods and the ability to produce fumonisins of the most prevailing species was determined. A total of 41 of the feedstuffs analyzed (71.9%) were found to contain Fusarium spp. Most contaminated substrates were corn (100%), cottonseed meal (100%), sorghum (80%), and soybean (80%). Wheat middlings and rice showed lower levels of contamination (40% and 20%, respectively), while no Fusarium spp. could be isolated from sunflower seed meal. The most prevalent species of Fusarium isolated were F. verticilliodes (70.8%), F.␣proliferatum (25.0%), and F. subglutinans (4.2%). All of them correspond to section Liseola.Production of fumonisins on corn by the isolated Fusarium was screened through liquid chromatography. Almost all strains of F. verticilliodes (97.1%) produced FB1 (5.6–25,846.4 mg/kg) and FB2 (3.4–7507.5 mg/kg). Similarly, almost all strains of F.␣proliferatum (91.7%) produced fumonisins but at lower levels than F.␣verticilliodes (FB1 from 6.9 to 3885.0 mg/kg, and FB2 from 34.3 to 373.8 mg/kg), while F. subglutinans did not produce these toxins. This is the first study in Colombia describing toxigenic Fusarium isolates from␣animal feedstuffs.     

Amsonia spp. as potential fuel crops for arid lands

The biomass of three desert plants, Amsonia kearneyana, A. grandiflora and A. palmeri, was used for the production of glucose and ethanol by simultaneous saccharification and fermentation techniques. Ethanol yields were 0.46 g g^-1 for A. keurneyana, 0.51 g g^-1 for A. grandiflora and 0.51 g g^-1 for A. palmeri. When the plant materials were saccharified into glucose only, the yields obtained were 0.35 g g^-1 for A. kearneyana, 0.39 g g^-1 for A. grandiflora and 0.22 g g^-1 for A. palmeri.H. Punnapayak is with the Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; J.J. Hoffmann is with the Bioresources Research Facility, University of Arizona, Tuscon, AZ 85706, USA.     

Increased resistance to antifungal antibiotics ofCandida spp. adhered to silicone

Summary The minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs) of amphotericin B, miconazole, ketoconazole, fluconazole, and itraconazole were determined for non-adhered cells and cells adhered to sections of a silicone urinary catheter. The densities of adhered cells were established with cells radiolabeled with tritiated leucine. Well defined MICs and MFCs were established for amphotericin B for representative adhered strains. In contrast, the azoles, especially fluconazole, did not give clear end points and the MICs and MFCs were arbitrarily determined. MFCs for the adhered cells generally were 2- to 5-fold higher than those of non-adhered cells. Techniques that include adhered-cell susceptibilities may be necessary before antifungal regimens for prosthetic device-associated yeast infections are appropriately defined.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.     

节杆菌环境适应性的基因组学研究进展

节杆菌分布广泛,能适应多种环境条件,而且多数节杆菌具有营养多功能性,能降解多种环境污染物,因而受到人们的广泛关注。近年来,随着多株节杆菌基因组的测序完成,人们对节杆菌环境适应性的分子机制有了全面的认识。基因组学研究结果表明,节杆菌在σ因子、氧化应激、渗透应激、饥饿应激、温度应激等胁迫应激反应相关基因方面的特点使其能够在多种环境条件下生存。本文挑选部分具有代表性的节杆菌基因组学研究,对其环境适应性的基因组学基础进行综述,以期为利用节杆菌进行环境污染修复提供理论基础,并为其它细菌的环境适应性机制研究提供参考。