共查询到20条相似文献,搜索用时 31 毫秒
1.
Alice L. den Hertog Dennis W. Visser Colin J. Ingham Frank H. A. G. Fey Paul R. Klatser Richard M. Anthony 《PloS one》2010,5(6)
Background
Even with the advent of nucleic acid (NA) amplification technologies the culture of mycobacteria for diagnostic and other applications remains of critical importance. Notably microscopic observed drug susceptibility testing (MODS), as opposed to traditional culture on solid media or automated liquid culture, has shown potential to both speed up and increase the provision of mycobacterial culture in high burden settings.Methods
Here we explore the growth of Mycobacterial tuberculosis microcolonies, imaged by automated digital microscopy, cultured on a porous aluminium oxide (PAO) supports. Repeated imaging during colony growth greatly simplifies “computer vision” and presumptive identification of microcolonies was achieved here using existing publically available algorithms. Our system thus allows the growth of individual microcolonies to be monitored and critically, also to change the media during the growth phase without disrupting the microcolonies. Transfer of identified microcolonies onto selective media allowed us, within 1-2 bacterial generations, to rapidly detect the drug susceptibility of individual microcolonies, eliminating the need for time consuming subculturing or the inoculation of multiple parallel cultures.Significance
Monitoring the phenotype of individual microcolonies as they grow has immense potential for research, screening, and ultimately M. tuberculosis diagnostic applications. The method described is particularly appealing with respect to speed and automation. 相似文献2.
3.
van Dooremalen C Gerritsen L Cornelissen B van der Steen JJ van Langevelde F Blacquière T 《PloS one》2012,7(4):e36285
Background
Recent elevated winter loss of honey bee colonies is a major concern. The presence of the mite Varroa destructor in colonies places an important pressure on bee health. V. destructor shortens the lifespan of individual bees, while long lifespan during winter is a primary requirement to survive until the next spring. We investigated in two subsequent years the effects of different levels of V. destructor infestation during the transition from short-lived summer bees to long-lived winter bees on the lifespan of individual bees and the survival of bee colonies during winter. Colonies treated earlier in the season to reduce V. destructor infestation during the development of winter bees were expected to have longer bee lifespan and higher colony survival after winter.Methodology/Principal Findings
Mite infestation was reduced using acaricide treatments during different months (July, August, September, or not treated). We found that the number of capped brood cells decreased drastically between August and November, while at the same time, the lifespan of the bees (marked cohorts) increased indicating the transition to winter bees. Low V. destructor infestation levels before and during the transition to winter bees resulted in an increase in lifespan of bees and higher colony survival compared to colonies that were not treated and that had higher infestation levels. A variety of stress-related factors could have contributed to the variation in longevity and winter survival that we found between years.Conclusions/Significance
This study contributes to theory about the multiple causes for the recent elevated colony losses in honey bees. Our study shows the correlation between long lifespan of winter bees and colony loss in spring. Moreover, we show that colonies treated earlier in the season had reduced V. destructor infestation during the development of winter bees resulting in longer bee lifespan and higher colony survival after winter. 相似文献4.
Iridovirus and microsporidian linked to honey bee colony decline 总被引:1,自引:0,他引:1
Bromenshenk JJ Henderson CB Wick CH Stanford MF Zulich AW Jabbour RE Deshpande SV McCubbin PE Seccomb RA Welch PM Williams T Firth DR Skowronski E Lehmann MM Bilimoria SL Gress J Wanner KW Cramer RA 《PloS one》2010,5(10):e13181
Background
In 2010 Colony Collapse Disorder (CCD), again devastated honey bee colonies in the USA, indicating that the problem is neither diminishing nor has it been resolved. Many CCD investigations, using sensitive genome-based methods, have found small RNA bee viruses and the microsporidia, Nosema apis and N. ceranae in healthy and collapsing colonies alike with no single pathogen firmly linked to honey bee losses.Methodology/Principal Findings
We used Mass spectrometry-based proteomics (MSP) to identify and quantify thousands of proteins from healthy and collapsing bee colonies. MSP revealed two unreported RNA viruses in North American honey bees, Varroa destructor-1 virus and Kakugo virus, and identified an invertebrate iridescent virus (IIV) (Iridoviridae) associated with CCD colonies. Prevalence of IIV significantly discriminated among strong, failing, and collapsed colonies. In addition, bees in failing colonies contained not only IIV, but also Nosema. Co-occurrence of these microbes consistently marked CCD in (1) bees from commercial apiaries sampled across the U.S. in 2006–2007, (2) bees sequentially sampled as the disorder progressed in an observation hive colony in 2008, and (3) bees from a recurrence of CCD in Florida in 2009. The pathogen pairing was not observed in samples from colonies with no history of CCD, namely bees from Australia and a large, non-migratory beekeeping business in Montana. Laboratory cage trials with a strain of IIV type 6 and Nosema ceranae confirmed that co-infection with these two pathogens was more lethal to bees than either pathogen alone.Conclusions/Significance
These findings implicate co-infection by IIV and Nosema with honey bee colony decline, giving credence to older research pointing to IIV, interacting with Nosema and mites, as probable cause of bee losses in the USA, Europe, and Asia. We next need to characterize the IIV and Nosema that we detected and develop management practices to reduce honey bee losses. 相似文献5.
Background
Fluorescence microscopy is a powerful tool to study the morphology and function of subcellular compartments or to determine the localization of proteins. The method is also regularly used for the analysis of parasitic protists including kinetoplastida.Results
Here, we report a significant autofluorescence of Leishmania tarentolae mitochondria. The autofluorescence, presumably caused by flavoproteins, was detectable using a variety of cell fixation protocols and had a maximum emission at approximately 538 nm. Stable signals were obtained with xenon lamps as a light source and filter sets that are commonly used for the detection of green fluorescent protein.Conclusions
On the one hand, we present a methodological approach to examine mitochondrial morphology or to study the colocalization of mitochondrial proteins without additional staining or labeling procedures. On the other hand, under certain experimental conditions, mitochondrial autofluorescence can result in false positive signals, demonstrating the necessity to analyze unlabeled cells as negative controls. 相似文献6.
7.
Kenta Nakamura Nathan Salomonis Kiichiro Tomoda Shinya Yamanaka Bruce R. Conklin 《PloS one》2009,4(11)
Background
Reprogramming adult human somatic cells to create human induced pluripotent stem (hiPS) cell colonies involves a dramatic morphological and organizational transition. These colonies are morphologically indistinguishable from those of pluripotent human embryonic stem (hES) cells. G protein-coupled receptors (GPCRs) are required in diverse developmental processes, but their role in pluripotent colony morphology and organization is unknown. We tested the hypothesis that Gi-coupled GPCR signaling contributes to the characteristic morphology and organization of human pluripotent colonies.Methodology/Principal Findings
Specific and irreversible inhibition of Gi-coupled GPCR signaling by pertussis toxin markedly altered pluripotent colony morphology. Wild-type hES and hiPS cells formed monolayer colonies, but colonies treated with pertussis toxin retracted inward, adopting a dense, multi-layered conformation. The treated colonies were unable to reform after a scratch wound insult, whereas control colonies healed completely within 48 h. In contrast, activation of an alternative GPCR pathway, Gs-coupled signaling, with cholera toxin did not affect colony morphology or the healing response. Pertussis toxin did not alter the proliferation, apoptosis or pluripotency of pluripotent stem cells.Conclusions/Significance
Experiments with pertussis toxin suggest that Gi signaling plays a critical role in the morphology and organization of pluripotent colonies. These results may be explained by a Gi-mediated density-sensing mechanism that propels the cells radially outward. GPCRs are a promising target for modulating the formation and organization of hiPS and hES cell colonies and may be important for understanding somatic cell reprogramming and for engineering pluripotent stem cells for therapeutic applications. 相似文献8.
Background
The echinocandins are lipopeptides that can be employed as antifungal drugs that inhibit the synthesis of 1,3-β-glucans within the fungal cell wall. Anidulafungin and caspofungin are echinocandins used in the treatment of Candida infections and have activity against other fungi including Aspergillus fumigatus. The echinocandins are generally considered fungistatic against Aspergillus species.Methods
Culture of A. fumigatus from conidia to microcolonies on a support of porous aluminium oxide (PAO), combined with fluorescence microscopy and scanning electron microscopy, was used to investigate the effects of anidulafungin and caspofungin. The PAO was an effective matrix for conidial germination and microcolony growth. Additionally, PAO supports could be moved between agar plates containing different concentrations of echinocandins to change dosage and to investigate the recovery of fungal microcolonies from these drugs. Culture on PAO combined with microscopy and image analysis permits quantitative studies on microcolony growth with the flexibility of adding or removing antifungal agents, dyes, fixatives or osmotic stresses during growth with minimal disturbance of fungal microcolonies.Significance
Anidulafungin and caspofungin reduced but did not halt growth at the microcony level; additionally both drugs killed individual cells, particularly at concentrations around the MIC. Intact but not lysed cells showed rapid recovery when the drugs were removed. The classification of these drugs as either fungistatic or fungicidal is simplistic. Microcolony analysis on PAO appears to be a valuable tool to investigate the action of antifungal agents. 相似文献9.
Jarrod J. Scott Kevin J. Budsberg Garret Suen Devin L. Wixon Teri C. Balser Cameron R. Currie 《PloS one》2010,5(3)
Background
Leaf-cutter ants use fresh plant material to grow a mutualistic fungus that serves as the ants'' primary food source. Within fungus gardens, various plant compounds are metabolized and transformed into nutrients suitable for ant consumption. This symbiotic association produces a large amount of refuse consisting primarily of partly degraded plant material. A leaf-cutter ant colony is thus divided into two spatially and chemically distinct environments that together represent a plant biomass degradation gradient. Little is known about the microbial community structure in gardens and dumps or variation between lab and field colonies.Methodology/Principal Findings
Using microbial membrane lipid analysis and a variety of community metrics, we assessed and compared the microbiota of fungus gardens and refuse dumps from both laboratory-maintained and field-collected colonies. We found that gardens contained a diverse and consistent community of microbes, dominated by Gram-negative bacteria, particularly γ-Proteobacteria and Bacteroidetes. These findings were consistent across lab and field gardens, as well as host ant taxa. In contrast, dumps were enriched for Gram-positive and anaerobic bacteria. Broad-scale clustering analyses revealed that community relatedness between samples reflected system component (gardens/dumps) rather than colony source (lab/field). At finer scales samples clustered according to colony source.Conclusions/Significance
Here we report the first comparative analysis of the microbiota from leaf-cutter ant colonies. Our work reveals the presence of two distinct communities: one in the fungus garden and the other in the refuse dump. Though we find some effect of colony source on community structure, our data indicate the presence of consistently associated microbes within gardens and dumps. Substrate composition and system component appear to be the most important factor in structuring the microbial communities. These results thus suggest that resident communities are shaped by the plant degradation gradient created by ant behavior, specifically their fungiculture and waste management. 相似文献10.
Background
Most plasmids replicate only within a particular genus or family.Methodology/Principal Findings
Here we describe an engineered high copy number expression vector, pBAV1K-T5, that produces varying quantities of active reporter proteins in Escherichia coli, Acinetobacter baylyi ADP1, Agrobacterium tumefaciens, (all Gram-negative), Streptococcus pneumoniae, Leifsonia shinshuensis, Peanibacillus sp. S18-36 and Bacillus subtilis (Gram-positive).Conclusions/Significance
Our results demonstrate the efficiency of pBAV1K-T5 replication in different bacterial species, thereby facilitating the study of proteins that don''t fold well in E. coli and pathogens not amenable to existing genetic tools. 相似文献11.
Meredith K. D. Hawking Donna M. Lecky Neville Q. Verlander Cliodna A. M. McNulty 《PloS one》2013,8(10)
Background
School visits to farms are a positive educational experience but pose risks due to the spread of zoonotic infections. A lesson plan to raise awareness about microbes on the farm and preventative behaviours was developed in response to the Griffin Investigation into the E. coli outbreak associated with Godstone Farm in 2009. This study evaluated the effectiveness of the delivery of the lesson plan in increasing knowledge about the spread of infection on the farm, amongst school students.Methods
Two hundred and twenty-five 9–11 year old students from seven junior schools in England participated. Two hundred and ten students filled in identical questionnaires covering microbes, hand hygiene, and farm hygiene before and after the lesson. Statistical analysis assessed knowledge change using difference in percentage correct answers.Results
Significant knowledge improvement was observed for all sections. In the ‘Farm Hygiene’ section, girls and boys demonstrated 18% (p<0.001) and 11% (p<0.001) improvement, respectively (girls vs. boys p<0.004). As girls had lower baseline knowledge the greater percentage improvement resulted in similar post intervention knowledge scores between genders (girls 80%, boys 83%).Conclusions
The lesson plan was successful at increasing awareness of microbes on the farm and infection prevention measures and should be used by teachers in preparation for a farm visit. 相似文献12.
Background
Protein transduction is safer than viral vector-mediated transduction for the delivery of a therapeutic protein into a cell. Fusion proteins with an arginine-rich cell-penetrating peptide have been produced in E. coli, but the low solubility of the fusion protein expressed in E. coli impedes the large-scale production of fusion proteins from E. coli.Results
Expressed protein ligation is a semisynthetic method to ligate a bacterially expressed protein with a chemically synthesized peptide. In this study, we developed expressed protein ligation-based techniques to conjugate synthetic polyarginine peptides to Cre recombinase. The conjugation efficiency of this technique was higher than 80%. Using this method, we prepared semisynthetic Cre with poly-L-arginine (ssCre-R9), poly-D-arginine (ssCre-dR9) and biotin (ssCre-dR9-biotin). We found that ssCre-R9 was delivered to the cell to a comparable level or more efficiently compared with Cre-R11 and TAT-Cre expressed as recombinant fusion proteins in E. coli. We also found that the poly-D-arginine cell-penetrating peptide was more effective than the poly-L-arginine cell-penetrating peptide for the delivery of Cre into cell. We visualized the cell transduced with ssCre-dR9-biotin using avidin-FITC.Conclusions
Collectively, the results demonstrate that expressed protein ligation is an excellent technique for the production of cell-permeable Cre recombinase with polyarginine cell-penetrating peptides. In addition, this approach will extend the use of cell-permeable proteins to more sophisticated applications, such as cell imaging.Electronic supplementary material
The online version of this article (doi:10.1186/s12896-015-0126-z) contains supplementary material, which is available to authorized users. 相似文献13.
Background
Corals are capable of launching diverse immune defenses at the site of direct contact with pathogens, but the molecular mechanisms of this activity and the colony-wide effects of such stressors remain poorly understood. Here we compared gene expression profiles in eight healthy Acropora hyacinthus colonies against eight colonies exhibiting tissue loss commonly associated with white syndromes, all collected from a natural reef environment near Palau. Two types of tissues were sampled from diseased corals: visibly affected and apparently healthy.Results
Tag-based RNA-Seq followed by weighted gene co-expression network analysis identified groups of co-regulated differentially expressed genes between all health states (disease lesion, apparently healthy tissues of diseased colonies, and fully healthy). Differences between healthy and diseased tissues indicate activation of several innate immunity and tissue repair pathways accompanied by reduced calcification and the switch towards metabolic reliance on stored lipids. Unaffected parts of diseased colonies, although displaying a trend towards these changes, were not significantly different from fully healthy samples. Still, network analysis identified a group of genes, suggestive of altered immunity state, that were specifically up-regulated in unaffected parts of diseased colonies.Conclusions
Similarity of fully healthy samples to apparently healthy parts of diseased colonies indicates that systemic effects of white syndromes on A. hyacinthus are weak, which implies that the coral colony is largely able to sustain its physiological performance despite disease. The genes specifically up-regulated in unaffected parts of diseased colonies, instead of being the consequence of disease, might be related to the originally higher susceptibility of these colonies to naturally occurring white syndromes.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1540-2) contains supplementary material, which is available to authorized users. 相似文献14.
Kyung Hoon Lee Ran Lee Won Young Lee Dong Hoon Kim Hak Jae Chung Jin Hoi Kim Nam Hyung Kim Suk Hwa Choi Jae Hwan Kim Hyuk Song 《PloS one》2014,9(10)
Background
In vitro culture of spermatogonial stem cells (SSCs) is important for exploration of SSCs self-renewal, differentiation, and manipulation. There are several reports on rodent SSC cultures; however, data on SSC cultures in domestic animals are limited. To provide basic scientific information on canine SSC cultures, we report canine testes development, and the development of spermatogonia-derived colonies (SDCs) for in vitro cultures.Methodology/Principal Findings
Testes from 2-, 3-, and 12-month-old beagles were used for histology, immunohistochemistry, in vitro culture, immunocytochemistry, and PCR. Protein gene product 9.5 (PGP9.5)-positive spermatogonia, both single and paired, were found to be abundant in the testes of 2-month-old beagles. stempro-34 and Dulbecco''s modified Eagle medium with 5% fetal bovine serum provided as useful substrates for culture of SDCs, and fibroblast growth factor (FGF) played a key role in colony formation. Colonies were positive for alkaline phosphatase and anti-PGP9.5 staining. The early spermatogonia and stem cell markers such as octamer binding protein 4 (Oct4), Nanog homeobox (Nanog), promyelocytic leukemia zinc finger (PLZF), PGP9.5, and GDNF family receptor alpha-1 (GFRα-1) were expressed in the colonies at higher levels than in the testis tissue.Conclusions
Testes of the 2-month-old beagles had abundant single and paired spermatogonia, which can be used for derivation of SDCs, and FGF was important for colony formation. 相似文献15.
Background
Allometric studies have shown that individual growth rate is inversely related to body size across a broad spectrum of organisms that vary greatly in size. Fewer studies have documented such patterns within species. No data exist directly documenting the influence of colony size on growth rate for microscopic, colonial organisms.Methodology/Principal Findings
To determine if similar negative relationships between growth rate and size hold for colonial organisms, we developed a technique for measuring the growth of individual colonies of a bloom-forming, toxic cyanobacterium, Microcystis aeruginosa using microscopy and digital image analysis. For five out of six genotypes of M. aeruginosa isolated from lakes in Michigan and Alabama, we found significant negative relationships between colony size and growth rate. We found large intraspecific variation in both the slope of these relationships and in the growth rate of colonies at a standard size. In addition, growth rate estimates for individual colonies were generally consistent with population growth rates measured using standard batch culture.Conclusions/Significance
Given that colony size varies widely within populations, our results imply that natural populations of colonial phytoplankton exist as a mosaic of individuals with widely varying ecological attributes (since size strongly affects growth rate, grazing mortality, and migration speed). Quantifying the influence of colony size on growth rate will permit development of more accurate, predictive models of ecological interactions (e.g., competition, herbivory) and their role in the proliferation of harmful algal blooms, in addition to increasing our understanding about why these interactions vary in strength within and across environments. 相似文献16.
Kenichi Tanaka Masaaki Nakayama Makoto Kanno Hiroshi Kimura Kimio Watanabe Yoshihiro Tani Yuki Kusano Hodaka Suzuki Yoshimitsu Hayashi Koichi Asahi Keiji Sato Toshio Miyata Tsuyoshi Watanabe 《PloS one》2013,8(12)
Background
Advanced glycation end product (AGE) accumulation is thought to be a measure of cumulative metabolic stress that has been reported to independently predict cardiovascular disease in diabetes and renal failure. The aim of this study was to evaluate the association between AGE accumulation, measured as skin autofluorescence, and the progression of renal disease in pre-dialysis patients with chronic kidney disease (CKD).Methods
Skin autofluorescence was measured noninvasively with an autofluorescence reader at baseline in 449 pre-dialysis patients with CKD. The primary end point was defined as a doubling of serum creatinine and/or need for dialysis.Results
Thirty-three patients were lost to follow-up. Forty six patients reached the primary end point during the follow-up period (Median 39 months). Kaplan-Meier analysis showed a significantly higher risk of development of the primary end points in patients with skin autofluorescence levels above the optimal cut-off level of 2.31 arbitrary units, derived by receiver operator curve analysis. Cox regression analysis revealed that skin autofluorescence was an independent predictor of the primary end point, even after adjustment for age, gender, smoking history, diabetes, estimated glomerular filtration rate and proteinuria (adjusted hazard ratio 2.58, P = 0.004).Conclusions
Tissue accumulation of AGEs, measured as skin autofluorescence, is a strong and independent predictor of progression of CKD. Skin autofluorescence may be useful for risk stratification in this group of patients; further studies should clarify whether AGE accumulation could be one of the therapeutic targets to improve the prognosis of CKD. 相似文献17.
Background
Recent research shows that visible-light responsive photocatalysts have potential usage in antimicrobial applications. However, the dynamic changes in the damage to photocatalyzed bacteria remain unclear.Methodology/Principal Findings
Facilitated by atomic force microscopy, this study analyzes the visible-light driven photocatalyst-mediated damage of Escherichia coli. Results show that antibacterial properties are associated with the appearance of hole-like structures on the bacteria surfaces. Unexpectedly, these hole-like structures were preferentially induced at the apical terminus of rod shaped E. coli cells. Differentiating the damages into various levels and analyzing the percentage of damage to the cells showed that photocatalysis was likely to elicit sequential damages in E. coli cells. The process began with changing the surface properties on bacterial cells, as indicated in surface roughness measurements using atomic force microscopy, and holes then formed at the apical terminus of the cells. The holes were then subsequently enlarged until the cells were totally transformed into a flattened shape. Parallel experiments indicated that photocatalysis-induced bacterial protein leakage is associated with the progression of hole-like damages, further suggesting pore formation. Control experiments using ultraviolet light responsive titanium-dioxide substrates also obtained similar observations, suggesting that this is a general phenomenon of E. coli in response to photocatalysis.Conclusion/Significance
The photocatalysis-mediated localization-preferential damage to E. coli cells reveals the weak points of the bacteria. This might facilitate the investigation of antibacterial mechanism of the photocatalysis. 相似文献18.
19.
Wenhui Pang Hefeng Wang Lei Shi Yueqi Sun Xiaoting Wang Mingming Wang Jianfeng Li Haibo Wang Guanggang Shi 《PloS one》2013,8(3)
Background
Hygiene hypothesis demonstrates that the lack of microbial exposure would promote the development of allergic airway disease (AAD). Therefore, the gut microbiota, including Escherichia coli (E. coli), would probably offer a potential strategy for AAD.Objective
To investigate whether E. coli infection is able to suppress the induction of AAD and to elucidate the underlying mechanisms.Methods
Nonpathogenic E. coli ATCC 25922 was infected by gavage before AAD phase in three patterns: 108 or 106 CFU in neonates or 108 CFU in adults. Then mice were sensitized and challenged with ovalbumin (OVA) to induce allergic inflammation in both the upper and lower airways. Hallmarks of AAD, in terms of eosinophil infiltration and goblet cell metaplasia in subepithelial mucosa, Th2 skewing of the immune response, and levels of T regulate cells (Tregs), were examined by histological analysis, ELISA, and flow cytometry, respectively.Results
E. coli, especially neonatally infected with an optimal dose, attenuated allergic responses, including a decrease in nasal rubbing and sneezing, a reduction in eosinophil inflammation and goblet cell metaplasia in subepithelial mucosa, decreased serum levels of OVA-specific IgE, and reduced Th2 (IL-4) cytokines. In contrast, this effect came with an increase of Th1 (IFN-r and IL-2) cytokines, and an enhancement of IL-10-secreting Tregs in paratracheal lymph nodes (PTLN).Conclusion
E. coli suppresses allergic responses in mice, probably via a shift from Th1 to Th2 and/or induction of Tregs. Moreover, this infection is age- and dose-dependent, which may open up novel possibilities for new therapeutic interventions. 相似文献20.