Ergosterol,the unusual dominant sterol of the pythiaceous fungus Zoophagus insidians

The pythiaceous fungus, Zoophagus insidians synthesizes ergosterol as its dominant sterol. This observation is unusual because the Pythiaceae were previously throught to be incapable of sterol synthesis and the pantonemic fungi in general to not produce ergosterol.     

L-arginine is essential for conidiation in the filamentous fungus Coniothyrium minitans

Conidiation is important in the life cycles of mitosporic fungi for survival and transmission. A full-length cDNA of one gene named CMCPS1 encoding L-arginine-specific carbamoyl-phosphate synthase was obtained from Coniothyrium minitans, a sclerotial parasite of the plant pathogenic fungus Sclerotinia sclerotiorum. T-DNA insertional disruption of CMCPS1 resulted in conidiation deficiency of mutant ZS-1T2029, and this was confirmed with the RNAi technique. The phenotype was restored by complementation with L-arginine, and the effect of L-arginine on conidiation may be mediated by nitric oxide, which is catalyzed by nitric oxide synthase (NOS). Conidiation of ZS-1T2029 was restored by sodium nitroprussiate, a NO donor; and conidiation of wild type strain ZS-1 could be suppressed by L-NAME, an inhibitor of NOS. The highest amount of NO in mycelia was detected at an early stage of conidiation (72 hpi) in liquid shake culture medium. Staining with the NO-sensitive fluorescent probe, DAF-FM DA, gave strong fluorescent signals in primordia and young pycnidia. This work presents the first report that L-arginine is involved in conidiation of C. minitans, and the possibility of L-arginine-derived nitric oxide-mediated conidiation among fungi and possible modes of action are discussed.     

Novel role of cytoplasmic dynein motor in maintenance of the nuclear number in conidia through organized conidiation in Aspergillus oryzae

Cytoplasmic dynein is a minus-end-directed, microtubule-dependent motor protein complex. DhcA, cytoplasmic dynein heavy chain in Aspergillus oryzae, contained four P-loops involved in ATP binding which were conserved as in cytoplasmic dynein heavy chains of other organisms. The amino acid sequence of A. oryzae DhcA was similar to cytoplasmic dynein heavy chains from other organisms except for the N-terminus of Saccharomyces cerevisiae Dyn1. Disruption of dhcA gene in the region encoding four P-loop motifs resulted in a defective growth and perturbed distribution of nuclei and vacuoles. The dhcA disruptant exhibited an abnormal morphology of conidial heads and conidia with an increased nuclear number. The present study implicates a novel role of cytoplasmic dynein in maintenance of the nuclear number in conidia through an organized conidiation.     

抗肿瘤银杏内生真菌Aspergillus oryzae YX-5发酵 培养基的优化

【目的】对一株具有抗肿瘤活性的银杏内生真菌Aspergillus oryzae YX-5的发酵培养基进行优化。【方法】以发酵后的菌体干重、粗提物质量和粗提物抗肿瘤活性为指标,通过单因素实验选出合适的碳源和氮源,再以选出的碳源、氮源以及K2HPO4、MgSO4·7H2O、KCl共5个因素进行正交实验,确定出最适宜的发酵培养基配方。【结果】YX-5的最佳发酵培养基配方为葡萄糖45 g/L,蛋白胨8 g/L,K2HPO4 0.5 g/L,MgSO4·7H2O 0.2 g/L,KCl 1 g/L,FeSO40.01 g/L。优化后菌体干重、代谢物的产量和抗肿瘤活性分别提高了41.88%、226.52%和19.31%。【结论】通过对米曲霉菌(Aspergillus oryzae)YX-5的发酵培养基进行优化,明显提高了粗提物产量和抗肿瘤活性,这对后期规模化发酵中减小发酵规模和降低工作量十分有利。     

The role of in vitro cultivation on symbiotic trait and function variation in a single species of arbuscular mycorrhizal fungus

In vitro propagation of AM fungi using transformed root cultures (TRC) is commonly used to obtain pure AM fungal propagules for use in research and industry. Early observations indicate that such an artificial environment can alter traits and function of AM fungi over time. We hypothesized that increased in vitro cultivation may promote ruderal strategies in fungi by enhancing propagule production and reducing mutualistic quality. To examine the effect of in vitro cultivation on the trait and function of AM fungi, we inoculated plants with 11 Rhizoglomus irregulare isolates which fell along a cultivation gradient spanning 80 generations. We harvested plants at 10, 20 and 30 d post inoculation to observe differences in fungal and plant traits post infection. In vitro cultivation led to increased spore production but reduced plant shoot phosphorus. Our results indicate that in vitro propagation may indirectly select for traits that affect symbiotic quality.     

Temperature-dependent development and oviposition models and life history characteristics of Amblyseius eharai (Amitai et Swirski) (Acari: Phytoseiidae) preying on Tetranychus urticae (Koch) (Acari: Tetranychidae)

Amblyseius eharai, a native predatory mite in Korea, has a potential as a biological control agent for small-sized pests. However, its ecological characteristics remain unclear. Thus, the objective of this study was to construct temperature-dependent development and oviposition models of A. eharai and evaluate its life table parameters. Its development was examined at 11 temperatures (18.0, 20.1, 21.6, 24.0, 24.1, 27.4, 28.6, 30.2, 32.0, 33.2, and 35.9 °C). The life table analysis was conducted using experimental data from 6 temperatures (18.0, 21.6, 24.1, 27.4, 30.2, and 33.2 °C). Development and fecundity of A. ehari were well described by the Briere 1 model and an extreme value function, respectively. The intrinsic rate of increase (r) was the highest (0.2619) at 27.4 °C and the lowest (0.0792) at 18.0 °C. Based on r values of A. eharai obtained in this study and published information of Calepitrimerus vitis, A. ehari has higher r values than C. vitis. A. eharai appears to have good potential as a biological control agent against C. vitis in vineyards.     

How feeding on mixed pollens of cattail and saffron affects Neoseiulus cucumeris (Acari: Phytoseiidae) performance

Predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) is a commercially available biocontrol agent against various pests of greenhouse crops, and it can feed on different diets, including small arthropods and pollen. This generalist predatory mite was reared on the mixture of two different plant pollens including cattail (35%), and saffron (65%) for 10 generations. The effects of mixed diet on the biological parameters of N. cucumeris were evaluated under laboratory conditions at 25 ± 1 °C, 60 ± 5% RH, and a photoperiod of 16:8 (L: D) h every 5 generations (G1, G5, and G10). In addition, the predation ability of nymphs and adults of N. cucumeris encountering the natural prey, Tetranychus urticae Koch was evaluated after 10 generations. The results showed that the quality of mass-reared N. cucumeris on a mixed diet of cattail and saffron pollens did not decrease up to 10 generations of rearing. The intrinsic rate of increase (r) of the predator in G1, G5, and G10 was 0.180, 0.189, and 0.199 day⁻¹, respectively. In addition, the r value was 0.181 day⁻¹ after switching this predator to T. urticae, and it had a high potential of predation (513 prey/generation). The results of this study revealed that rearing N. cucumeris for 10 generations on a mixed diet of saffron and cattail pollens did not affect the performance of the predator negatively.     

The effect of incubation media on the water exchange of snapping turtle (Chelydra serpentina) eggs and hatchlings

Summary The effect of two different incubation media, sand and vermiculite, on the water exchange of eggs and the mass of hatchlings of snapping turtles (Chelydra serpentina) was assessed. The eggs were incubated fully buried in either sand or vermiculite at 30 °C and egg mass was measured periodically throughout incubation. The wet and dry masses of each hatchling and its residual yolk were measured at the end of incubation. The media had similar water potentials () but their thermal conductivities differed 2.8-fold. The eggs experienced a net water gain during incubation. The rates of water uptake between treatments were not statistically different throught the first 36 days of incubation but were statistically different thereafter, with eggs incubating in sand taking up water at about twice the rate of eggs incubating in vermiculite. Hatchling masses were similar to both media but hatchling water contents were significantly different. Hatchlings incubated in sand had lower water contents than hatchlings incubated in vermiculite even though the eggs in sand took up more water. Hatchling mass was correlated with egg water exchange for eggs incubated in vermiculite but not for eggs incubated in sand. The difference in egg water exchange in the two media appears to be attributable to differences in the thermal conductivity of the media. The presence of such a thermal effect supports the hypothesis that the eggs exchanged water with the media as water vapor. Egg water exchange was limited by the shell and shell membranes and not by the media. The shell and shell membranes appear to present an effective barrier to water uptake.Abbreviations M _{H 2 O} water flux (cm³·day^-1) - L _p hydraulic conductivity (cm·day^-1·kPa^-1) - A shell area (cm²) - A _p pore area (cm²) - l shell thickness (cm) - r pore radius (cm) - viscosity (kPa·day) - P _{EH 2 O} egg water potential (kPa) - P _{AH 2 O} medium water potential (kPa) - G _{H 2 O} water vapor conductance (cm³·day^-1·kPa^-1) - D _{H 2 O} diffusion coefficient (cm²·day^-1) - R gas constant (cm³·kPa·K^-1·cm^-3) - T temperature (K) - P _{EH 2 O} egg water vapor pressure (kPa) - P _{AH 2 O} medium water vapor pressure (kPa) - d egg diameter - K soil hydraulic conductivity (cm²·day^-1·kPa^-1) - DHM hatchling dry mass - WHM hatchiling wet mass - WU water uptake - IM initial egg mass     

Life History of Kampimodromus aberrans as a predator of Phytoptus avellanae (Acari: Phytoseiidae, Phytoptidae)

The biology of Kampimodromus aberrans (Oudemans), a predator of the big bud mite, Phytoptus avellanae Nalepa, was studied under laboratory conditions. All experiments were conducted on hazelnut leaf discs in an incubator at 25 ± 1 °C, with 16:8 h L:D, at an average daily relative air humidity of 76%. Observations were made twice daily for the immature stages and daily for the adults to determine developmental time, survival and fecundity. The mean developmental time for females was 6.90 days and for males was 7.10 days, and mean adult longevity for females was 11.67 days. The mean total and daily egg production were 12.67 and 1.85 eggs, respectively. The net reproduction rate (R₀) was 7.09 females/female, intrinsic rate of increase (r_m) was 0.153 female/female/day and mean generation time (T₀) was 12.80 days. The mortality rate of immature stages was 0.66% and the sex ratio was 0.51 female.     

The effect of environmental factors on the growth rate of Karenia brevis (Davis) G. Hansen and Moestrup

The red tide dinoflagellate Karenia brevis (Davis) G. Hansen and Moestrup is noted for causing mass mortalities of marine organisms in the Gulf of Mexico. Most research has focused on culture isolates from the eastern Gulf of Mexico. In this investigation, we examine the effects of light, temperature and salinity on the growth rate of K. brevis from the western Gulf of Mexico. Growth rates of K. brevis were determined under various combinations of irradiance (19, 31, 52, 67, and 123 μmol m⁻² s⁻¹), salinity (25, 30, 35, 40 and 45), and temperature (15, 20, 25, and 30 °C). Maximum growth rates varied from 0.17 to 0.36 div day⁻¹ with exponential growth rates increasing with increasing irradiance. Little or no growth was supported at 19 μmol photons m⁻² s⁻¹ for any experiment. Maximum growth rates at 15 °C were much lower than at other temperatures. Maximum growth rates of the Texas clone (SP3) fell within the range of Florida clones reported in the literature (0.17–0.36 div day⁻¹ versus 0.2–1.0 div day⁻¹). The Texas clone SP3 had a very similar light saturation point compared to that of a Florida isolate (Wilson's clone) (67 μmol m⁻² s⁻¹ versus 65 μmol m⁻² s⁻¹), and light compensation (20–30 μmol m⁻² s⁻¹1). The upper and lower salinity tolerance of the Texas clone was similar than that of some Florida clones (45 versus 46 and 25 versus 22.5, respectively). In our study, the Texas clone had the same temperature tolerance reported for Florida clones (15–30 °C). While individual clones can vary considerably in maximum growth rates, our results indicate only minor differences exist between the Texas and Florida strains of K. brevis in their temperature and salinity tolerance for growth. While the literature notes lower salinity occurrences of K. brevis in nearby Louisiana, our isolate from the southern Texas coast has the higher salinity requirements typical of K. brevis in the eastern Gulf of Mexico.     

Effect of light and phosphate on conidiation in the fungus Verticillium agaricinum

Verticillium agaricinum (Link) Corda, grown in a yeast extract-sucrose medium, conidiated abundantly in darkness after irradiation with near ultraviolet (290–400 nm) for 15 min or blue light (400–550 nm) for 60 min. Few conidia were formed in total darkness. Exposure to 30 min of near ultraviolet light suppressed conidiation. Conidiation was also suppressed by phosphate in excess of 10⁻⁴ M irrespective of light condition. After irradiation with near ultraviolet light for more than 30 min, there was a cessation of growth and a change in colony color from yellow to reddish. The color does not appear to be due to a carotenoid because the colonies turned from red to yellow when covered with acid. At pH lower than 6.0 the pigment has an absorption maximum around 390 nm, whereas at higher pH it is around 540 nm. Thus, it appears that irradiation of V. agaricinum with near ultraviolet may cause an increase in pH, which in turn produces the change of colony color from yellow to reddish.     

Genetic variation of morphological characters within a single isolate of the endomycorrhizal fungus Glomus clarum (Glomaceae)

The nature of variation in morphological characters in spores of arbuscular endomycorrhizal fungi (Order Glomales, Class Zygomycetes) has received little attention, despite the importance of these characters in modern taxonomy of the order. We tested the hypothesis that genetic variation exists in spore size and color (presumably important taxonomic characters) within a single isolate of the glomalean fungus Glomus clarum. Phenotypic variation in size and color of spores was determined from a pot culture population (designated P). A 10% selection pressure was imposed on replicate pot cultures of the first progeny culture generation (G1) by selecting the smallest, largest, yellowest, and whitest spores from the P generation and inoculating Sorghum bicolor plants. The experiment was repeated for another generation (G2), but with a 5% selection pressure. In both the G1 and G2 generations, significant differences in spore size and color were observed among the various treatments, indicating substantial genetic variation in these characters. Despite efforts to keep the physical environment constant across generations, we observed variation in the overall means of spore size and color among the generations (regardless of treatment), indicating a strong nongenetic influence on character expression. This study provides empirical evidence that will help delimit species boundaries among isolates of Glomus clarum and similar morphospecies. It also demonstrates a promising method to help elucidate the nature of character diversity in obligately asexual fungi.     

The effect of copper on the growth of wood-rotting fungi and a blue-stain fungus

The effect of copper (II) ions on the growth of three brown-rot fungi, six white-rot fungi and one blue-stain fungus in solid medium was evaluated. The fungi were grown in malt extract agar with different concentrations of copper added, and the radial growth rate was determined. At the end of the incubation period, the mycelial biomass and the media pH were determined. The white-rot and blue-stain fungus grew up to 3 mM and 6 mM copper, respectively and the brown-rot fungi were the only ones that grew up to 10 mM, with higher growth rates than those shown by the other fungi. In general, the brown-rot fungi produced greater acidification in the culture media than the white-rot fungi and blue-stain fungus, and the acidification increased when the amount of copper was increased. The biomass production for the different species, in the absence or presence of copper, was not related to the radial growth rate, and the fungal species that produced the greatest biomass amounts did not correspond to those that presented the highest growth rates. The brown-rot fungi Wolfiporia cocos and Laetiporus sulfureus and blue-stain fungus Ophiostoma sp. demonstrated greater tolerance to high copper concentrations in solid medium than the white-rot fungi, determined as radial growth rate. On the other hand, the highest biomass producers in solid medium with copper added were the white-rot fungi Ganoderma australe and Trametes versicolor and the brown-rot fungus Gloeophyllum trabeum.     

The role of environmental factors for the composition of microbial communities of saline lakes in the Novosibirsk region (Russia)

Background

Nothing is currently known about microbial composition of saline lakes of the Novosibirsk region and its dependence on physical-chemical parameters of waters. We studied the structure of microbial communities of saline lakes of the Novosibirsk region and the effect of physical-chemical parameters of waters on microbial communities of these lakes.

Results

According to the ion content, the lakes were classified either as chloride or chloride-sulfate types. Water salinity ranges from 4.3 to 290 g L⁻¹. Many diverse microbial communities were found. Filamentous and colonial Cyanobacteria of the genera Scytonema, Aphanocapsa, and/or filamentous Algae dominated in littoral communities. Spatial and temporal organization of planktonic microbial communities and the quantities of Archaea and Bacteria were investigated using fluorescent in situ hybridization. We have found that the dominant planktonic component is represented by Archaea, or, less frequently, by Bacteria. Various phylogenetic groups (Bacteria, Archaea, Algae, and Cyanobacteria) are nonuniformly distributed. The principal component analysis was used to detect environmental factors that affect microorganism abundance. We found the principal components responsible for 71.1 % of the observed variation. It was demonstrated that two-block partial least squares was a better method than principal component analysis for analysis of the data. We observed general relationships between microbial abundance and water salinity.

Conclusions

We have performed the first-ever study of the structure of the microbial communities of eleven saline lakes in the Novosibirsk region along with their physical-chemical parameters of waters. Our study demonstrates that saline lakes in the Novosibirsk region contain a unique microbial communities that may become a prolific source of microorganisms for fundamental and applied studies in various fields of ecology, microbiology, geochemistry, and biotechnology, and deserve further metagenomic investigation.

     

The role of environmental factors for the composition of microbial communities of saline lakes in the Novosibirsk region (Russia)

Background

Nothing is currently known about microbial composition of saline lakes of the Novosibirsk region and its dependence on physical-chemical parameters of waters. We studied the structure of microbial communities of saline lakes of the Novosibirsk region and the effect of physical-chemical parameters of waters on microbial communities of these lakes.

Results

According to the ion content, the lakes were classified either as chloride or chloride-sulfate types. Water salinity ranges from 4.3 to 290 g L^?1. Many diverse microbial communities were found. Filamentous and colonial Cyanobacteria of the genera Scytonema, Aphanocapsa, and/or filamentous Algae dominated in littoral communities. Spatial and temporal organization of planktonic microbial communities and the quantities of Archaea and Bacteria were investigated using fluorescent in situ hybridization. We have found that the dominant planktonic component is represented by Archaea, or, less frequently, by Bacteria. Various phylogenetic groups (Bacteria, Archaea, Algae, and Cyanobacteria) are nonuniformly distributed. The principal component analysis was used to detect environmental factors that affect microorganism abundance. We found the principal components responsible for 71.1 % of the observed variation. It was demonstrated that two-block partial least squares was a better method than principal component analysis for analysis of the data. We observed general relationships between microbial abundance and water salinity.

Conclusions

We have performed the first-ever study of the structure of the microbial communities of eleven saline lakes in the Novosibirsk region along with their physical-chemical parameters of waters. Our study demonstrates that saline lakes in the Novosibirsk region contain a unique microbial communities that may become a prolific source of microorganisms for fundamental and applied studies in various fields of ecology, microbiology, geochemistry, and biotechnology, and deserve further metagenomic investigation.

     

环境因子对AM真菌多样性的影响

土壤,气候和地理因子等环境因子对丝枝菌根（AM）真菌多样性有重要影响,本文系统地综述了最近10年来AM真菌生态学在该方面的最新研究成果,分析当前研究中所存在的问题和动向。     

The plant growth‐promoting fungus Fusarium equiseti and the arbuscular mycorrhizal fungus Glomus mosseae stimulate plant growth and reduce severity of anthracnose and damping‐off diseases in cucumber (Cucumis sativus) seedlings

To alleviate the environmental contamination due to persistent chemical usage, approaches to integrated pest management were conceived. In this perspective, microbe–microbe interactions such as mycorrhizal relationships with other soil microbiota in the rhizosphere like the plant growth‐promoting fungi (PGPF) are particularly important. Better understanding of the interactions between beneficial microbial groups is imperative in the identification of possible synergistic or antagonistic effects to improve their practical usage as biocontrol agents or biofertilizers. In this study, the consequence of co‐inoculation of the arbuscular mycorrhizal fungus (AMF) Glomus mosseae (Gm) and the PGPF Fusarium equiseti (isolates GF18‐3 and GF19‐1) in terms of plant growth enhancement, root and rhizosphere colonisation, and development of anthracnose (Colletotrichum orbiculare) and damping‐off (Rhizoctonia solani AG‐4) diseases in cucumber plants was investigated under controlled conditions. The amendment of either GF18‐3 or GF19‐1 singly or in combination with Gm indicated a general tendency to significantly enhance the shoot dry weight (SDW) of cucumber plants at 4 weeks after planting (WAP). Similarly, Gm alone significantly enhanced SDW at 4 WAP. Gm showed a tendency to depress root colonisation by F. equiseti but such antagonistic effect was not observed in the rhizosphere soil. Both GF18‐3 and GF19‐1 significantly reduced percent root colonisation of Gm. However, these general tendencies may vary with the inoculum densities of AMF and PGPF. Both F. equiseti and Gm inoculated singly significantly increased percent of protection against anthracnose, but the combined inoculation was more effective in controlling the disease compared to single inoculation. The inoculation of the cucumber seedlings with GF18‐3, GF19‐1 or Gm, 6 or 12 days prior to damping‐off pathogen inoculation, increased percent of protection against damping‐off disease. This study shows that the co‐inoculation of F. equiseti and Gm resulted in additive effect on the suppression of anthracnose disease in cucumber.     

Macroinvertebrates in the Demmerik ditches (The Netherlands): The role of environmental structure

The relation between the different microhabitats and habitats and the quantitative distribution of macroinvertebrates was investigated as well as the applicability of different sampling devices. Data processing took place by means of multivariate analysis (Flexclus, Canoco). It was concluded that the spatial-physical structure is more important to macroinvertebrates than the plant species. In fact, this spatial physical structure can be indicated as the mesh size of a (micro-)habitat. In order from open vegetation, shore/dense vegetation, artificial substrate, bottom material, and filamentous algae the mesh size decresed. It is advisable to use different sampling devices to sample a macroinvertebrate community.     

The capability of the predacious fungus Arthrobotrys oligospora (Hyphomycetales) to reduce numbers of infective larvae of Ostertagia ostertagi (Trichostrongylidae) in cow pats and herbage during the grazing season in Denmark

Artificially prepared cow pats containing Ostertagia ostertagi eggs were deposited on two pasture plots in May, June and July 1986. Half of the cow pats, placed on one plot, were inoculated with 2000 conidia per gram faeces of the predacious fungus Arthrobotrys oligospora. On the other plot fungus-free control cow pats were placed at the same time. In the faeces generally fewer infective O. ostertagi larvae developed in the inoculated than in the control cow pats. On the herbage around the control cow pats deposited in May, June and July a maximum concentration of infective larvae was found at the same time on the 6th of August 1986. At that time the herbage larval infectivity around inoculated cow pats deposited in May, June and July was subject to a reduction of 48%, 89% and 46%, respectively, compared with fungus-free control cow pats. This experiment indicates that a concentration of 2000 A. oligospora conidia per gram faeces results in a significant lowering of the herbage larval infectivity during the grazing season in Denmark.