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1.
Tamarix aphylla is an evergreen tree that has invaded the drawdown zone of Lake Mead, a large reservoir on the Lower Colorado River. We performed competition experiments between T. aphylla and T. ramosissima, and between T. aphylla and the native tree Salix gooddingii. Root:shoot ratios and biomass were higher in S. gooddingii than both Tamarix species, and T. ramosissima grew taller than T. aphylla and S. gooddingii when treatments with single plants and no competition were compared. Tamarix aphylla outcompeted the native S. gooddingii, but had competitive abilities that were slightly inferior to T. ramosissima. The competitive abilities of T. aphylla may and help explain why this species is not as widespread as its congeners, although because of T. aphylla's larger size, the species may be as serious a threat to native riparian ecosystems as T. ramosissima. These results indicate that management actions should be taken to ensure that T. aphylla does not further invade riparian ecosystems in the southwestern United States.  相似文献   

2.
Trametes versicolor and Agaricus augustus, with a maximum tolerable concentration (MTC) of 80 μg ml−1 tribromophenol (TBP), were selected to evaluate TBP biodegradation capacity. These fungi were capable of decreased TBP concentrations and A. augustus was also capable of biotransforming TBP to tribromoanisole (TBA). Peroxidase and laccase activities were observed in the T. versicolor supernatant but not in that of A. augustus. These tolerance levels could be due to either lignolytic enzymes that degrade TBP or the ability of the fungi to biotransform TBP to tribromoanisole, respectively. The sustained ability of T. versicolor to degrade TBP (total of 40 μg ml−1) in the presence of an additional carbon source suggests that it may have potential applications in the degradation of forestry industry waste.  相似文献   

3.
The management of Tetranychus urticae, a key pest of clementine trees, is mainly based on the use of acaricides. However, more environmentally safe measures, such as biological control, are being encouraged. Life-history traits of the three most abundant phytoseiid mites associated with T. urticae on this crop (Euseius stipulatus, Phytoseiulus persimilis and Neoseiulus californicus) were studied. The experiments were performed under laboratory conditions (25°C, 80 ± 5% RH and 16:8 h (L:D)) on clementine leaves and T. urticae as prey. Euseius stipulatus could not complete its life cycle, whereas P. persimilis and N. californicus completed it satisfactorily. The estimated intrinsic rate of increase (r m) was significantly higher for P. persimilis (0.344 day−1) than for N. californicus (0.244 day−1) and both were higher than the r m value of T. urticae on clementine leaves. Implications of these results for the biological control of T. urticae in this crop are discussed.  相似文献   

4.
Genetic engineering of a wide variety of plant species has led to the improvement of plant traits. In this study, the genetic transformation of two potentially important flowering ornamentals, Melastoma malabathricum and Tibouchina semidecandra, with sense and antisense dihydroflavonol-4-reductase (DFR) genes using the Agrobacterium-mediated method was carried out. Plasmids pBETD10 and pBETD11, each harbouring the DFR gene at different orientations (sense and antisense) and selectable marker nptII for kanamycin resistance, were used to transform M. malabathricum and T. semidecandra under the optimized transformation protocol. Putative transformants were selected in the presence of kanamycin with their respective optimized concentration. The results indicated that approximately 4.0% of shoots and 6.7% of nodes for M. malabathricum regenerated after transforming with pBETD10, whereas only 3.7% (shoots) and 5.3% (nodes) regenerated with pBETD11 transformation. For the selection of T. semidecandra, 5.3% of shoots and 9.3% of nodes regenerated with pBETD10 transformation, while only 4.7% (shoots) and 8.3% (nodes) regenerated after being transformed with pBETD11. The presence and integration of the sense and antisense DFR genes into the genome of M. malabathricum and T. semidecandra were verified by polymerase chain reaction (PCR) and nucleotide sequence alignment and confirmed by southern analysis. The regenerated putative transformants were acclimatized to glasshouse conditions. Approximately 31.0% pBETD10-transformed and 23.1% pBETD11-transformed M. malabathricum survived in the glasshouse, whereas 69.4% pBETD10-transformed and 57.4% pBETD11-transformed T. semidecandra survived. The colour changes caused by transformation were observed at the budding stage of putative T. semidecandra transformants where greenish buds were produced by both T. semidecandra harbouring the sense and antisense DFR transgenes. Besides that, the production of four-petal flowers also indicated another morphological difference of putative T. semidecandra transformants from the wild type plants which produce five-petal flowers.  相似文献   

5.
Onychomycosis is a fungal infection of the nails with broad aetiological scope, and it represents 18–40% of all onychopathies and 39% of all superficial mycotic infections. From July 1996 to December 1999, samples of nails were collected from 588 patients with presumptive diagnosis of onychomycosis at the Dermatology and Mycology Divisions EPM\UNIFESP, Brazil, and the diagnosis was confirmed in 247 of these cases. The most common pathogens isolated in this study were yeasts in 52% of positive cultures (Candida albicans 18.3%, Candida parapsilosis 13.8%, other species of Candida 15.4% and other yeasts 4.6%), followed by dermatophytes in 40.6% of positive cultures (the most commonly isolated organisms were Trichophyton rubrum in 33.2%, followed by Trichophyton mentagrophytes in 6.3% and others 1.2%). Non-dermatophyte moulds were isolated in 7.4% of positive cultures (Fusarium spp. 4.5%, Nattrassia mangiferae 2.3% and Aspergillus spp. 0.6%). Distal and lateral subungual onychomycosis (DLSO) was the commonest clinical pattern 44.6% followed by free edge onycholysis (FEO) 38.8% and others. In conclusion, this study demonstrated that T. rubrum is the main agent causing onychomycosis in toenails, and species of genus Candida were the main agents isolated in fingernail onychomycosis in our region.  相似文献   

6.
The presence of the exotic Argentine ant, Linepithema humile Mayr (Hymenoptera: Dolichoderinae), nitrogen enrichment, and early-season herbivory by the specialist beetle Trirhabda bacharidis (Coleoptera: Chrysomelidae) have been shown, through separate experiments, to affect the densities of insect herbivores of the coastal shrub Baccharis halimifolia (Asteraceae), in Florida. Using a fully-factorial field experiment, we examined the relative importance of all three of these factors to the six most common insect herbivore species utilizing this host plant in a West Central Florida coastal habitat. The presence of ants affected more herbivore species than either early-season herbivory by larval T. bacharidis or nitrogen enrichment. Experimental reductions of L. humile resulted in reductions of an aphid, its coccinellid predators, and adult T. bacharidis, and increases of two species of leafminers and one species of stemborer. Due to the strong negative effects of stemborer herbivory on host plant survival, the increase in stemborer abundance led to increased host plant mortality. Early-season herbivory by larval T. bacharidis only affected the abundance of aphids and their predators, both of which were more abundant on trees with reduced early-season herbivory. Nitrogen fertilization had the most limited effects and only T. bacharidis larvae achieved higher densities on fertilized trees. Our results indicate that aphid tending by the exotic L. humile affects other insects on B. halimifolia more so than herbivory by the exploitative competitor T. bacharidis or nitrogen as a limiting nutrient.  相似文献   

7.
We investigated the intestinal microflora of coastal fish including Takifugu niphobles using both culture techniques and library cloning. As a result, the numbers of bacteria appeared on agar media were 1.0 × 104 to 1.4 × 109 CFU/g (colony forming units/gram), whereas those of total bacteria stained with 4′,6-diamidino-2-phenylindole were 4.7 × 1010 to 1.9 × 1011 cells/gram, irrespective of different fish species. In addition, the culture technique showed that the intestinal microflora in all specimens was mainly composed of the genus Vibrio. In contrast, the direct count method showed that spirochaetes with length of 2.5-4.5 μm were present in the intestinal contents of T. niphobles at high densities, whereas such bacteria could not be detected in those of other fish species. Library cloning yielded the sequences of 16S rRNA genes that were divided into seven taxonomic categories of bacteria including Actinobacteria, Bacilli, Clostridia, Gammaproteobacteria, Mollicutes, Spirochaetes and an unclassified bacterial group. These results demonstrate that the molecular diversity of the intestinal bacteria in T. niphobles based on the clone library method reflects the direct observation by fluorescence microscopy to some extent.  相似文献   

8.
Trametes versicolor 1 was shown to grow on phenol as its sole carbon and energy source. The culture growth and degradation ability dependence on culture medium pH value was observed. The optimal pH value of a liquid Czapek salt medium was 6.5. The investigated strain utilized completely 0.5 g/l phenol in 6 days. The dynamics of the phenol degradation process was investigated. The process was characterized by specific growth rate μmax 0.33 h−1, metabolic coefficient k = 4.4, yield coefficient Y x/s  = 0.23 and rate of degradation Q = 0.506 h−1. The intracellular activities of phenol hydroxylase (0.333 U/mg protein) and cis,cis-muconate lactonizing enzyme (0.41 U/mg protein) were demonstrated for the first time in this fungus. In an attempt to estimate the occurrence of gene sequences in T. versicolor 1 related to phenol degradation pathway a dot blot analysis with total DNA isolated from this strain was performed. Two synthetic oligonucleotides were used as hybridizing probes. One of the probes was homologous to the 5′end of phyA gene coding for phenol hydroxylase in Trichosporon cutaneum ATCC 46490. The other probe was created on the basis of cis,cis-muconate lactonizing enzyme coding gene in T. cutaneum ATCC 58094. The results of these investigations showed that T. versicolor 1 may carry genes similar to those of Trichosporon cutaneum capable to degrade phenol.  相似文献   

9.
Tipula paludosa (Diptera: Nematocera) is the major insect pest in grassland in Northwest Europe and has been accidentally introduced to North America. Oviposition occurs during late August and first instars hatch from September until mid-October. Laboratory and field trials were conducted to assess the control potential of entomopathogenic nematodes (EPN) (Steinernema carpocapsae and S. feltiae) and Bacillus thuringiensis subsp. israelensis (Bti) against T. paludosa and to investigate whether synergistic effects can be exploited by simultaneous application of nematodes and Bti. Results indicate that the early instars of the insect are most susceptible to nematodes and Bti. In the field the neonates prevail when temperatures tend to drop below 10 °C. S. carpocapsae, reaching >80% control, is more effective against young stages of T. paludosa than S. feltiae (<50%), but the potential of S. carpocapsae might be limited by temperatures below 12 °C. Mortality of T. paludosa caused by Bti was not affected by temperature even at 4 °C but the lethal time increased with decreasing temperatures. Synergistic effects of Bti and EPN against T. paludosa were observed in 3 out of 10 combinations in laboratory assays but not in a field trial. The potential of S. carpocapsae was demonstrated in field trials against early instars in October reaching an efficacy of >80% with 0.5 million nematodes m−2 at soil temperatures ranging between 3 and 18 °C. Results with Bti were strongly influenced by the larval stage and concentration. Against early instars in autumn between 74 and 83% control was achieved with 13 kg ha−1 Bti of 5,700 International Toxic Units (ITUs) and 20 kg ha−1 of 3,000 ITUs. Applications in spring against third and fourth instars achieved between 0 and 32% reduction. The results indicate that application of Bti and nematodes will only be successful and economically feasible during the early instars and that the success of S. carpocapsae is dependent on temperatures >12 °C. Synergistic effects between S. carpocapsae and Bti require more detailed investigations in the field to determine maximal effect.  相似文献   

10.
Aim To investigate the possible association of three SNPs, XRCC2 C41657T, XRCC2 G4234C and XRCC3 A17893G with susceptibility to esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) in a population of northern China. Methods XRCC2 C41657T, XRCC2 G4234C and XRCC3 A17893G SNP were genotyped by polymerase-chain reaction (PCR)–restriction fragment length polymorphism (RFLP) analysis in 583 cancer patients (329 ESCC and 254 GCA) and 614 healthy controls. Results The genotype distribution of the XRCC2 C41657T in ESCC and GCA patients were significantly different from that in healthy controls (P values = 0.04 and 0.04 respectively). And a significant difference was found in the allele distribution of GCA patients from that in controls (= 0.01). The XRCC2 C41657T polymorphism was associated with a modest enhancement in ESCC risk and GCA risk: OR for C/T genotype was 1.38 (1.01–1.89) in GCA risk and for T/T genotype was 2.24 (1.10–4.57) in ESCC risk. When stratified for age, smoking status and family history of UGIC, the C/T genotype showed a modest significant trend on the risk of GCA patients in the groups of age ≤50 years and non-smokers, the adjusted OR were 2.84 (1.21–6.66) and 1.62 (1.06–2.49). The T/T genotype significantly increased the susceptibility of GCA patients in negative family history of UGIC (3.04, 1.02–8.32) and to ESCC patients in the group of age >50 years (3.03, 1.31–6.98), Negative family of UGIC (3.03, 1.12–7.07) and smokers (2.64, 1.02–6.83). The genotype and allele distribution of XRCC2 G4234C and XRCC3 A17893G in ESCC and GCA patients were not significantly different from that in healthy controls (all P values were above 0.05). Conclusion In this study, we found that the C41657T polymorphism of XRCC2 genes might modify the risk of ESCC and GCA development.  相似文献   

11.
Stored product mites are pests of serious economic and medical importance. Recently, it has been shown that the biological control of these pests based on the use of natural compounds and predators had a high potential for success. In this study, we investigated the suppression of three pest mites by combination of the predator Cheyletus malaccensis Oudemans, 1913 and bean flour (Phaseolus vulgaris), which is an antifeedant. Wheat grain (100 g) was contaminated with 100 individuals (Acarus siro (Linnaeus, 1758), Aleuroglyphus ovatus (Troupeau, 1878) or Tyrophagus putrescentiae (Schrank, 1781)). We added bean flour in concentrations of 0, 1, 5 and 10 g kg−1 (wt/wt) and/or the predator with initial predator/prey ratios 0, 1/50, 1/25 and 1/10. The experiment was carried out under abiotic conditions that are optimal for pest development. After 21 days, pest and predators numbers were recorded. Application of flour significantly reduced populations of A. siro, slightly reduced populations of T. putrescentiae, the efficiency increased with increasing concentration. A. ovatus was not affect by bean flour. Populations of all mite species were successfully reduced by the sole addition of C. malaccensis, with a higher efficiency at higher Cheyletus ratios. The additive effect of the predator and flour was mainly apparent in the reduction of T. putrescientae. The population of C. malaccensis was not affected by the presence of bean flour. It is therefore recommended to use bean flour for the reduction of A. siro, a combination of bean flour and Cheyletus for the reduction of T. putrescientae, and only Cheyletus for the reduction of A. ovatus. Handling Editor: Arne Janssen.  相似文献   

12.
Despite the advances in transgenesis, transformation technologies still rely on the introduction of a selectable marker gene to identify cells and tissues that have integrated the gene of interest in their genome. The continuous presence of the marker genes in the transgenics is often controversial as it can potentially have multiple undesirable impacts. The present study employed the self-excising Cre-loxP system to generate marker-free Arabidopsis thaliana expressing the agronomically important glyoxalase I (glyI) gene from Brassica juncea to confer salt stress tolerance. A binary vector was constructed wherein the salt-inducible rd29A promoter was used to drive the expression of the glyI gene and the transformants of A. thaliana were recovered using kanamycin resistance as the selectable marker. The neomycin phosphotransferase II (nptII) gene was flanked by the loxP sites followed by the introduction of a heat-inducible Cre-recombinase in between the loxP sites. The kanamycin-resistant transgenic lines of A. thaliana using this vector showed an ability to withstand stress imposed by 150 mM NaCl. The exposure of the T2 transgenic lines to a mild heat shock (37°C) resulted in the recovery of salt-tolerant, kanamycin-sensitive T3 progeny. Molecular analyses of the T3 transgenic lines following the heat shock treatment confirmed the excision of the nptII gene and the completion of their life cycle in the presence of 150 mM NaCl-induced stress.  相似文献   

13.
We isolated and characterized 12 polymorphic microsatellite loci in the Malagasy endemic, Tina striata Radlk. (Sapindaceae). The number of alleles per locus ranged from 2 to 6 (N = 28 individuals). Polymorphic information content ranged from 0.132 to 0.767 and observed heterozygosity from 0.154 to 0.800. These markers will be valuable in estimating outcrossing rates and genetic variation in populations of T. striata, and aid in the conservation of populations of T. striata and other closely related species in the Malagasy Sapindaceae.  相似文献   

14.
A survey for natural entomopathogenic fungi of two spotted spider mite (Tetranychus urticae) adults was made in Erzurum, Turkey, during the period 2006. Tetranychus urticae (65.8%) infected with a strain of the fungus Cladosporium cladosporioides were found. Thirteen isolates of C. cladosporioides were assessed against T. urticae, in a single dose (8 × 106 conidia ml −1), laboratory bioassay on bean leaflets. The total mortality percentage caused by C. cladosporioides isolates varied from 50.95 to 74.76% and LT50 values ranged from 2.34 to 3.90 days. The results revealed that isolates of C. cladosporioides were effective against two spotted spider mite. This is the first record of natural infection of T. urticae by C. cladosporioides.  相似文献   

15.
The impact of invasive alien species on native species is of increasing global concern. Invasive plants have various negative effects on natives through competition; however, relatively little is known about competition for pollination. The relationship between Japanese native dandelions (Taraxacum spp.) and invasive congeners may be a typical case of such an interaction. For example, native dandelions are being replaced by invasive congeners, especially in urban and suburban areas of Japan. To explain this phenomenon, we hypothesized that when natives are mixed with attractive invasives, natives may suffer from reduced seed set because invasives deprive natives of pollinators or because pollinators frequently move between species, resulting in interspecific pollen transfer. To test this hypothesis, we studied the effect of the invasive dandelion T. officinale on the pollination and seed set of the native T. japonicum using artificial arrays of monospecific and mixed-species plots as well as natural populations. Taraxacum officinale attracted more pollinator visits, perhaps because it produced more nectar than T. japonicum. The number of pollinator visits to T. japonicum was reduced when the congeners were grown together, and pollinators moved frequently between the two species. The proportion of seed set for T. japonicum was reduced in the presence of T. officinale in both artificial arrays and natural populations. These results support our hypothesis that interspecific competition for pollination plays an important role in the recent replacement of native dandelions by invasive congeners in Japan. Because invasive dandelions are apomicts, negative effects are incurred only by sexual natives. Thus, this system can be recognized as a rare case of interspecific interaction through pollination.  相似文献   

16.
Biochemical parameters of the angiotensin converting enzyme-like activity (ACELA) in the gills of two Antarctic teleosts, Chionodraco hamatus and Trematomus bernacchii were characterized. Enzymatic activity was revealed following hydrolysis of a specific substrate of angiotensin-converting enzyme N-[3-(2-furyl)acryloyl]l-phenylalanyl-glycyl-glycine (FAPGG) and metabolites were separated by reverse phase HPLC analysis. The results showed similar Km values for the substrate FAPGG at 5°C for the two species with an increase of Km value for T. bernacchii at 25°C. The optimum pH value was 8.5 at 25°C and optimum chloride concentrations were about 300 mM. In T. bernacchii the optimum temperature for maximum enzyme activity was 50°C, while maximum activity in C. hamatus occurred at 35°C. Lisinopril was more efficient in inhibiting ACELA in C. hamatus with an I 50 value of 16.83 ± 5.11 nM, compared to an I 50 value of 30.66 ± 5.19 nM in T. bernacchii. In conclusion, it appears that some biochemical parameters of ACELA in C. hamatus differ from those in T. bernacchii, probably due to different ways that the enzyme adapts to the constantly cold temperatures of the animal’s environment.  相似文献   

17.
Summary  The first occurrence of the genus Metarungia Baden (Acanthaceae) in west Africa is recorded with the discovery of an isolated population of the widespread eastern African taxon M. pubinervia (T. Anderson) Baden in eastern Nigeria. The conservation status of this species is discussed.  相似文献   

18.
Various seed dressing and soil application formulations were developed from Trichoderma viride, T. virens and T. harzianum to increase the shelf life of bio-formulations used to manage dry root rot (Rhizoctonia bataticola) of mungbean (Vigna radiata), a major yield limiting factor in mungbean production. The shelf life of the formulations developed in the present study was monitored by counting colony forming units (cfu) up to 25 months of storage at room temperature (26 ± 8 °C). A newly developed seed dressing formulation, Pusa 5SD based on peat powder (47.5%), Sabudana powder (Manihot esculenta) (47.5%) and carboxymethyl cellulose (5%) and a newly developed soil application formulation, Pusa Biopellet (PBP) based on sodium alginate, aluminium silicate, Sabudana powder and tap water (1:5:5:100 w/w/w/v) exhibited longer shelf life. Another formulation Pusa Biogranule (PBG) based on wheat and pulse brans varied in cfu counts during different periods of storage. Pusa 5SD could be used up to 25 months of storage while PBP 10G and PBG 5 could be used up to 15 months of storage (>105 cfu). The efficacy of the formulations was evaluated in pot experiments against the disease. In these experiments, T. harzianum based PBP 10G and PBG 5 for soil application, and Pusa 5SD for seed treatment were found to be superior to others in reducing the dry root rot incidence, and increasing the seed germination and shoot and root lengths. However, a combination of soil application of PBP 10G (T. harzianum) and seed treatment with T. harzianum based Pusa 5SD + carboxin was found superior to the use of any of these formulations alone in reducing the dry root rot incidence (87.2%) and increasing the seed germination (43.0%), shoot length (40.3%), root length (37.0%) and grain yield (54.6%) of mungbean crop over those of untreated control under sick field conditions.  相似文献   

19.
This work evaluated the ovicidal effect of the nematophagous fungi Monacrosporium sinense (SF53), Monacrosporium thaumasium (NF34) and Pochonia chlamydosporia (VC1) on Taenia taeniaeformis eggs in laboratory conditions. T. taeniaeformis eggs were plated on 2% water-agar with the grown isolates and control without fungus and examined at seven and fourteen days post-inoculation. At the end of the experiment, P. chlamydosporia showed ovicidal activity (P < 0.01) on T. taeniaeformis eggs unlike the other two species, mainly for internal egg colonization with percentage results of 32.2–54.0% at 7th and 14th day, respectively. The other fungi only showed lytic effect without morphological damage to eggshell. Results demonstrated that P. chlamydosporia was in vitro effective against Taenia taeniaeformis eggs unlike the other fungi. In this way, the use of P. chlamydosporia is suggested as a potential biological control agent for eggs of this cestode.  相似文献   

20.
Resumen  La especie nueva Thinouia restingae, de las regiones nordeste y sudeste de Brasil, es descrita, ilustrada y comparada con la especie más próxima, T. ventricosa. Adicionalmente se describen caracteres de venación de los folíolos y micromorfológicos del polen. La especie nueva pertenece a Thinouia sección Petalodine, la cual se caracteriza por los pétalos iguales o mayores que el apéndice. También se presenta una clave para todas las especies de Thinouia reportadas hasta la fecha para Brasil.
A new species, Thinouia restingae, from northeastern and southeastern Brazil, is described, illustrated, and compared to its putative closest relative, T. ventricosa. Additionally, venation characters of the leaflets and micromorphological characters of pollen grains are described. The new species belongs to Thinouia section Petalodine, which is characterized by petals that are equal or longer than their appendage. A key to species of Thinouia presently known from Brazil is also included.
  相似文献   

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