The repellency and toxicity of a CO2-derived cedarwood oil (CWO) was evaluated against actively questing unfed nymphs of four species of hard ticks: Amblyomma americanum (L.), Dermacentor variabilis (Say), Ixodes scapularis Say, and Rhipicephalus sanguineus (Latreille). Using a vertical climb bioassay for repellency, nymphs of these species avoided a CWO-treated filter paper in proportional responses to treatment concentrations. At 60 min of exposure, I. scapularis nymphs were most sensitive with 50% repellency concentration (RC50) of 19.8 µg cm?2, compared with RC50 of 30.8, 83.8 and 89.6 µg cm?2 for R. sanguineus, D. variabilis and A. americanum, respectively. Bioassays determined the lethal concentration for 50% (LC50) and 90% (LC90) mortality of nymphs exposed to CWO in treated vials after 24- and 48-h exposure. After 24 h exposure, the LC50 values were 1.25, 3.45 and 1.42 µg cm?2 and LC90 values were 2.39, 7.59 and 4.14 µg cm?2 for D. variabilis, I. scapularis and R. sanguineus, respectively, but had minimal effect on A. americanum. After 48 h exposure, the LC50 values were 4.14, 0.78, 0.79 and 0.52 µg cm?2, and LC90 values were 8.06, 1.48, 1.54 and 1.22 µg cm?2 for A. americanum, D. variabilis, I. scapularis and R. sanguineus, respectively. The repellency of CWO on tick species decreased with time. The repellency and toxicity bioassays demonstrated concentration-dependent responses of tick nymphs to the oil, indicating the potential of the CO2-derived cedarwood oil be developed as an eco-friendly repellent and/or acaricide.
相似文献Background
Tick Subolesin and its ortholog in insects and vertebrates, Akirin, have been suggested to play a role in the immune response through regulation of nuclear factor-kappa B (NF-kB)-dependent and independent gene expression via interaction with intermediate proteins that interact with NF-kB and other regulatory proteins, bind DNA or remodel chromatin to regulate gene expression. The objective of this study was to characterize the structure and regulation of subolesin in Ixodes scapularis. I. scapularis is a vector of emerging pathogens such as Borrelia burgdorferi, Anaplasma phagocytophilum and Babesia microti that cause in humans Lyme disease, anaplasmosis and babesiosis, respectively. The genome of I. scapularis was recently sequenced, and this tick serves as a model organism for the study of vector-host-pathogen interactions. However, basic biological questions such as gene organization and regulation are largely unknown in ticks and other arthropod vectors.Principal Findings
The results presented here provide evidence that subolesin/akirin are evolutionarily conserved at several levels (primary sequence, gene organization and function), thus supporting their crucial biological function in metazoans. These results showed that NF-kB (Relish) is involved in the regulation of subolesin expression in ticks, suggesting that as in other organisms, different NF-kB integral subunits and/or unknown interacting proteins regulate the specificity of the NF-kB-mediated gene expression. These results suggested a regulatory network involving cross-regulation between NF-kB (Relish) and Subolesin and Subolesin auto-regulation with possible implications in tick immune response to bacterial infection.Significance
These results advance our understanding of gene organization and regulation in I. scapularis and have important implications for arthropod vectors genetics and immunology highlighting the possible role of NF-kB and Subolesin/Akirin in vector-pathogen interactions and for designing new strategies for the control of vector infestations and pathogen transmission. 相似文献Repellent and acaricidal activity of essential oils extracted from three varieties of basil (Ocimum basilicum L.) were evaluated on blacklegged ticks (Ixodes scapularis Say) and American dog ticks (Dermacentor variabilis Say) in laboratory conditions. Essential oils were extracted and characterized through gas chromatography-mass spectrometry, and tested at different concentrations for long-term repellent activity using horizontal bioassays. In addition, basil essential oils were combined with an inert material (i.e., granite rock dust) with known insecticidal and miticidal properties to assess acaricidal activities against adult ticks. Among the tested basil varieties, var. Jolina essential oil at 15% vol/vol concentration repelled 96% of tested ticks up to 2 h post-treatment. The EC50 for I. scapularis nymphs was 4.65% vol/vol (95% confidence interval: 4.73–4.57). In acaricidal tests, the combination of essential oil from var. Aroma 2 at 10% wt/wt with rock dust resulted in 100% tick mortality after only 24 h post-exposure, with a LD50 of 3.48% wt/wt (95% CI 4.05–2.91) for freshly prepared treatment tested on I. scapularis adults. The most common compounds detected in basil essential oils by GC–MS were linalool (52.2% in var. Nu Far, 48.2% in Aroma 2, 43.9% in Jolina), sabinene (6.71% in Nu Far, 8.99% in Aroma 2, 8.11% in Jolina), eugenol (11.2% in Jolina, 8.71% in Aroma 2), and estragole (18.2% in Nu Far). The use of essential oils alone and in combination with rock dust provides an innovative and environmentally friendly approach for managing ticks and inhibiting vector-borne disease transmission.
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Background
Recent studies of Lactobacillus delbrueckii subsp. bulgaricus GLB44 plus a proton‐pump inhibitor (PPI) reported cures of more than 90% of patients with active Helicobacter pylori infections.Aim
To confirm the high H. pylori cure rates reported previously.Method
A pilot study was done in healthy H. pylori‐infected volunteers using 3‐gram sachet (3 billion cells) of L. delbrueckii GLB44 plus 22.3 mg of esomeprazole b.i.d., for 14 days. The result was determined by urea breath testing 4 weeks after therapy. Stopping rules required for ending enrollment if less than 3 of the first 10 subjects were cured.Results
Nine subjects were entered and because all failed to achieve negative urea breath test, the stopping rule required the study to end.Conclusion
We were unable to confirm reports of achieving a high H. pylori cure rate with L. delbrueckii GLB44 plus a PPI. 相似文献Aim
In this study, the biological variation for improvement of the nutritive value of wheat straw by 12 Ceriporiopsis subvermispora, 10 Pleurotus eryngii and 10 Lentinula edodes strains was assessed. Screening of the best performing strains within each species was made based on the in vitro degradability of fungal‐treated wheat straw.Methods and Results
Wheat straw was inoculated with each strain for 7 weeks of solid state fermentation. Weekly samples were evaluated for in vitro gas production (IVGP) in buffered rumen fluid for 72 h. Out of the 32 fungal strains studied, 17 strains showed a significantly higher (P < 0·05) IVGP compared to the control after 7 weeks (227·7 ml g?1 OM). The three best Ceriporiopsis subvermispora strains showed a mean IVGP of 297·0 ml g?1 OM, while the three best P. eryngii and L. edodes strains showed a mean IVGP of 257·8 and 291·5 ml g?1 OM, respectively.Conclusion
Ceriporiopsis subvermispora strains show an overall high potential to improve the ruminal degradability of wheat straw, followed by L. edodes and P. eryngii strains.Significance and Impact of the Study
Large variation exists within and among different fungal species in the valorization of wheat straw, which offers opportunities to improve the fungal genotype by breeding. 相似文献![点击此处可从《Ecology and evolution》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《The journal of gene medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Background
Macrophage inhibitory factor (MIF) is a pro‐inflammatory cytokine modulating monocyte motility and a pleiotropic regulator of different biological and cellular processes. The MIF‐173G/C (rs755622) polymorphism is found in the promoter region and affects its activity. The present study investigated the MIF polymorphism as a risk factor for the development of acute lymphoblastic leukemia (ALL) in Egyptian children.Methods
We analyzed the MIF‐173G/C (rs755622) polymorphism in 180 ALL cases and 150 healthy control children by amplification of the gene using a polymerase chain reaction followed by restriction endonuclease digestion and running on an agarose gel for visualization of the product.Results
We found a significant incidence of the homozygous polymorphic (CC) genotype and the combined polymorphic genotypes (GC + CC) in ALL patients compared to healthy controls (p = 0.001 and p = 0.007, respectively), whereas the wild‐type genotype (GG) was more common in healthy controls (p = 0.006). Multivariate logistic regression analysis adjustment for MIF different genotypes and other potential risk factors such as age, sex and parental smoking indicated that the CC genotype is the only significant risk factor for the test (p = 0.02). We also noted that, by increasing the C‐allele representation within the gene [GC, CC], there was an increase in total leukocytic count (p = 0.09 and p = 0.001, respectively) that may reflect the bad prognostic impact of the polymorphic allele, although further studies are needed.Conclusions
The results of the present study indicate that the MIF‐173G/C (rs755622) polymorphism is a risk factor for childhood ALL development with respect to both homozygous and combined polymorphic genotypes. In addition, the increased leukocytic count in synchronization with the increased representation of the polymorphic C‐allele may reflect its bad prognostic impact. 相似文献![点击此处可从《植被学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Background
The stress‐gradient hypothesis predicts a shift from facilitative to competitive plant interactions with decreasing abiotic stress. This has been supported by studies along elevation and temperature gradients, but also challenged by the hypothesis of a facilitation collapse at extremely harsh sites. Although facilitation is known to be important in primary succession, few studies have examined these hypotheses along primary succession gradients.Aim
To examine whether there is a relationship between the presence of the circumpolar cushion plant Silene acaulis and other species, and if so, whether there is a shift between positive and negative interactions along a primary succession gradient in a glacier foreland.Location
Finse, southern Norway.Methods
We examined the performance of the common alpine forb Bistorta vivipara, species richness of vascular plants, bryophytes and lichens, and the number of seedlings and fertile vascular plants in S. acaulis cushions, and control plots without S. acaulis, along a succession gradient with increasing distance from a glacier front, and thus decreasing abiotic stress. To examine if S. acaulis cushions modify the abiotic environment, we recorded soil temperature, moisture, organic content and pH in cushions and control plots.Results
Bistorta vivipara performed better, as shown by bigger leaves in S. acaulis cushions compared to control plots in the harshest part of the gradient close to the glacier. There were few differences in B. vivipara performance between cushion and control plots in the more benign environment further away from the glacier. This suggests a shift from facilitative to mainly neutral interactions by S. acaulis on the performance of B. vivipara with decreasing abiotic stress. A trend, although not significant, of higher vascular species richness and fertility inside S. acaulis cushions along the whole gradient, suggests that S. acaulis also facilitates community‐level species richness. The causal mechanism of this facilitation is likely that the cushions buffer extreme temperatures.Conclusions
Our results support the stress‐gradient hypothesis for the relationship between the cushion plant S. acaulis and the performance of a single species along a primary succession gradient in a glacier foreland. S. acaulis also tended to increase vascular plant species richness and fertility regardless of stress level along the gradient, suggesting facilitation at the community level. We found no collapse of facilitation at the most stressful end of the gradient in this alpine glacier foreland. 相似文献Aim
To examine the inhibition effects of rhizosphere fungal strain MF‐91 on the rice blast pathogen Magnaporthe grisea and sheath blight pathogen Rhizoctonia solani.Methods and Results
Rhizosphere fungal strain MF‐91 and its metabolites suppressed the in vitro mycelial growth of R. solani. The inhibitory effect of the metabolites was affected by incubation temperature, lighting time, initial pH and incubation time of rhizosphere fungal strain MF‐91. The in vitro mycelial growth of M. grisea was insignificantly inhibited by rhizosphere fungal strain MF‐91 and its metabolites. The metabolites of rhizosphere fungal strain MF‐91 significantly inhibited the conidial germination and appressorium formation of M. grisea. Moreover, the metabolites reduced the disease index of rice sheath blight by 35·02% in a greenhouse and 57·81% in a field as well as reduced the disease index of rice blast by 66·07% in a field. Rhizosphere fungal strain MF‐91 was identified as Chaetomium aureum based on the morphological observation, the analysis of 18S ribosomal DNA internal transcribed spacer sequence and its physiological characteristics, such as the optimal medium, temperature and initial pH for mycelial growth and sporulation production.Conclusions
Rhizosphere fungus C. aureum is effective in the biocontrolling of rice blast pathogen M. grisea and sheath blight pathogen R. solani both in in vitro and in vivo conditions.Significance and Impact of the Study
This study is the first to show that rhizosphere fungus C. aureum is a potential fungicide against rice blast and sheath blight pathogens. 相似文献Aims
The objective was to determine the effect of the isoflavone biochanin A (BCA) on rumen cellulolytic bacteria and consequent fermentative activity.Methods and Results
When bovine microbial rumen cell suspensions (n = 3) were incubated (24 h, 39°C) with ground hay, cellulolytic bacteria proliferated, short‐chain fatty acids were produced and pH declined. BCA (30 μg ml?1) had no effect on the number of cellulolytic bacteria or pH, but increased acetate, propionate and total SCFA production. Addition of BCA improved total digestibility when cell suspensions (n = 3) were incubated (48 h, 39°C) with ground hay, Avicel, or filter paper. Fibrobacter succinogenes S85, Ruminococcus flavefaciens 8 and Ruminococcus albus 8 were directly inhibited by BCA. Synergistic antimicrobial activity was observed with BCA and heat killed cultures of cellulolytic bacteria, but the effects were species dependent.Conclusions
These results indicate that BCA improves fibre degradation by influencing cellulolytic bacteria competition and guild composition.Significance and Impact of the Study
BCA could serve as a feed additive to improve cellulosis when cattle are consuming high‐fibre diets. Future research is needed to evaluate the effect of BCA on fibre degradation and utilization in vivo. 相似文献Aims
To purify and primarily characterize an anti‐Alicyclobacillus bacteriocin produced by Bifidobacterium animalis subsp. animalis CICC 6165, suggested to be named bificin C6165.Methods and Results
During purification of the bificin C6165, optimal recovery was achieved with ammonium sulfate precipitation followed by two chromatographic steps. Mass spectrometry analyses revealed a distinctive peak corresponding to a molecular mass of 3395·1 Da. This bacteriocin was heat stable, effective after refrigerated storage and freeze–thaw cycles. The primary mode of action of bificin C6165 is most probably due to pore formation, as indicated by the efflux of K+ from metabolically active cells of Alicyclobacillus acidoterrestris. In the presence of 10 mmol l?1 gadolinium, bificin C6165 did not affect cells of Alicyclobacillus acidoterrestris. This suggests that the mode of action of bificin C6165 relies on a net negatively charged cell surface.Conclusions
Bificin C6165 is indeed a novel bacteriocin and it exhibited remarkable potency for Alicyclobacillus control.Significance and Impact of the Study
Application of bacteriocins in preservation of fruit juices has seldom been studied. Bificin C6165 may be an alternative method to control juice spoilage by this Alicyclobacillus acidoterrestris and meet increasing consumer demand for nature and artificial chemical additive‐free food products. 相似文献![点击此处可从《Journal of Biogeography》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Aim
Reconstruct the long‐term ecosystem dynamics of the region across an elevational gradient as they relate to climate and local controls. In particular, we (1) describe the dominant conifers' history; (2) assess changes in vegetation composition and distribution; and (3) note periods of abrupt change versus stability as means of better understanding vegetation responses to environmental variability.Location
Greater Yellowstone Ecosystem (GYE; USA).Time period
16.5 ka bp ‐present.Major taxa studied
Juniperus, Picea, Abies, Pinus, Pseudotsuga.Methods
The vegetation reconstruction was developed from 15 pollen records. Results were interpreted based on modern pollen–vegetation relationships estimated from a suite of regression‐based approaches.Results
Calibrated pollen data suggest that late‐glacial vegetation, dominated by shrubs and Juniperus, lacks a modern counterpart in the area. Picea, Abies and Pinus expanded at 16 ka bp in association with postglacial warming and co‐occurred in mixed‐conifer parkland/forest after 12 ka bp . This association along with Pinus contorta forest, which was present after 9 ka bp , has persisted with little change at middle and high elevations to the present day. This stability contrasts with the dynamic history of plant communities at low elevations, where shifts between parkland, steppe and forest over the last 8,000 years were likely driven by variations in effective moisture and fire.Main conclusions
The postglacial vegetation history of the GYE highlights the dynamic nature of mountain ecosystems and informs on their vulnerability to future climate change: (1) most of the conifers have been present in the area for >12,000 years and survived climate change by adjusting their elevational ranges; (2) some plant associations have exhibited stability over millennia as a result of nonclimatic controls; and (3) present‐day forest cover is elevationally more compressed than at any time in history, probably due to the legacy of the Medieval Climate Anomaly and the Little Ice Age. 相似文献![点击此处可从《Journal of applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Aims
We aim to determine if Pseudomonas fluorescens is a viable biological control for Erwinia tracheiphila within the insect vector, Acalymma vittatum.Methods and Results
Pseudomonas fluorescens secreted fluorescein and inhibited growth of E. tracheiphila in disc diffusion assays. To determine if this antagonism was conserved within the insect vector, we performed in vivo assays by orally injecting beetles with bacterial treatments and fluorescent in situ hybridization to determine bacterial presence within the alimentary canal.Conclusions
Pseudomonas fluorescens inhibited the growth of E. tracheiphila on a nutrient‐limiting medium. In situ experiments demonstrated that P. fluorescens is maintained within the alimentary canal of the beetle for at least 4 days, and co‐occurred with E. tracheiphila. When beetles were first presented with Pseudomonas and then challenged with E. tracheiphila, E. tracheiphila was not recovered via FISH after 4 days. These data suggest that P. fluorescens has potential as a biological control agent to limit E. tracheiphila within the insect vector.Significance and Impact of the Study
This is a novel approach for controlling E. tracheiphila that has the potential to decrease reliance on insecticides, providing a safer environment for pollinators and growers. 相似文献![点击此处可从《Journal of medical primatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Background
The physiological mechanisms that allow for sleeping in a vertical position, which is primordial for arboreal primates, have not been studied yet.Methods
A non‐invasive polysomnographic study of 6 spider monkeys (Ateles geoffroyi) was conducted. The relative beta power of the motor cortex and its linear relation with muscle tone in the facial mentalis muscle and the abductor caudae medialis muscle of the tail during wakefulness and sleep stages were calculated.Results
A strong negative linear relationship (r = ?.8, P = .03) was found between the relative power of the beta2 band in the left motor cortex and abductor caudae medialis muscle tone during delta sleep.Conclusions
The left motor cortex, through beta2 band activity, interacts with abductor caudae medialis muscle tonicity during delta sleep. This interaction takes part in the mechanisms that regulate the sleep postures. 相似文献![点击此处可从《Helicobacter》网站下载免费的PDF全文](/ch/ext_images/free.gif)