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1.  Phylogenomically Guided Identification of Industrially Relevant GH1 β-Glucosidases through DNA Synthesis and Nanostructure-Initiator Mass Spectrometry 
ACS Chemical Biology  2014;9(9):2082-2091.
Harnessing the biotechnological potential of the large number of proteins available in sequence databases requires scalable methods for functional characterization. Here we propose a workflow to address this challenge by combining phylogenomic guided DNA synthesis with high-throughput mass spectrometry and apply it to the systematic characterization of GH1 β-glucosidases, a family of enzymes necessary for biomass hydrolysis, an important step in the conversion of lignocellulosic feedstocks to fuels and chemicals. We synthesized and expressed 175 GH1s, selected from over 2000 candidate sequences to cover maximum sequence diversity. These enzymes were functionally characterized over a range of temperatures and pHs using nanostructure-initiator mass spectrometry (NIMS), generating over 10,000 data points. When combined with HPLC-based sugar profiling, we observed GH1 enzymes active over a broad temperature range and toward many different β-linked disaccharides. For some GH1s we also observed activity toward laminarin, a more complex oligosaccharide present as a major component of macroalgae. An area of particular interest was the identification of GH1 enzymes compatible with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), a next-generation biomass pretreatment technology. We thus searched for GH1 enzymes active at 70 °C and 20% (v/v) [C2mim][OAc] over the course of a 24-h saccharification reaction. Using our unbiased approach, we identified multiple enzymes of different phylogentic origin with such activities. Our approach of characterizing sequence diversity through targeted gene synthesis coupled to high-throughput screening technologies is a broadly applicable paradigm for a wide range of biological problems.
doi:10.1021/cb500244v
PMCID: PMC4168791  PMID: 24984213
2.  The Multifaceted Mast Cell in Inflammatory Bowel Disease 
Inflammatory bowel diseases  2014;20(12):2364-2378.
Mast cells (MCs) are tissue-resident immune cells that carry out protective roles against pathogens. In disease states, such as inflammatory bowel disease, these granulocytes release a diverse array of mediators that contribute to inflammatory processes. They also participate in wound repair and tissue remodeling. In this review, the composition of MCs and how their phenotypes can be altered during inflammation of the gastrointestinal tract is detailed. Animal and human clinical studies that have implicated the participation of MCs in inflammatory bowel disease are reviewed, including the contribution of the cell’s mediators to clinical symptoms, stress-triggered inflammation, and fistula and strictures. Studies that have focused on negating the proinflammatory roles of MCs and their mediators in animal models suggest new targets for therapies for patients with inflammatory bowel disease.
doi:10.1097/MIB.0000000000000142
PMCID: PMC4428674  PMID: 25401721
inflammatory bowel disease; ulcerative colitis; Crohn’s disease; mast cell; tryptase; chymase
3.  Fecal Microbiota Transplantation via Colonoscopy for Recurrent C. difficile Infection 
Fecal Microbiota Transplantation (FMT) is a safe and highly effective treatment for recurrent and refractory C. difficile infection (CDI). Various methods of FMT administration have been reported in the literature including nasogastric tube, upper endoscopy, enema and colonoscopy. FMT via colonoscopy yields excellent cure rates and is also well tolerated. We have found that patients find this an acceptable and tolerable mode of delivery. At our Center, we have initiated a fecal transplant program for patients with recurrent or refractory CDI. We have developed a protocol using an iterative process of revision and have performed 24 fecal transplants on 22 patients with success rates comparable to the current published literature. A systematic approach to patient and donor screening, preparation of stool, and delivery of the stool maximizes therapeutic success. Here we detail each step of the FMT protocol that can be carried out at any endoscopy center with a high degree of safety and success.
doi:10.3791/52154
PMCID: PMC4396937  PMID: 25549239
Immunology; Issue 94; C.difficile; colonoscopy; fecal transplant; stool; diarrhea; microbiota
4.  Gastrointestinal Behçet's disease: A review 
Behçet’s disease (BD) is an idiopathic, chronic, relapsing, multi-systemic vasculitis characterized by recurrent oral and genital aphthous ulcers, ocular disease and skin lesions. Prevalence of BD is highest in countries along the ancient silk road from the Mediterranean basin to East Asia. By comparison, the prevalence in North American and Northern European countries is low. Gastrointestinal manifestations of Behçet’s disease are of particular importance as they are associated with significant morbidity and mortality. Although ileocecal involvement is most commonly described, BD may involve any segment of the intestinal tract as well as the various organs within the gastrointestinal system. Diagnosis is based on clinical criteria - there are no pathognomonic laboratory tests. Methods for monitoring disease activity on therapy are available but imperfect. Evidence-based treatment strategies are lacking. Different classes of medications have been successfully used for the treatment of intestinal BD which include 5-aminosalicylic acid, corticosteroids, immunomodulators, and anti-tumor necrosis factor alpha monoclonal antibody therapy. Like inflammatory bowel disease, surgery is reserved for those who are resistant to medical therapy. A subset of patients have a poor disease course. Accurate methods to detect these patients and the optimal strategy for their treatment are not known at this time.
doi:10.3748/wjg.v21.i13.3801
PMCID: PMC4385527  PMID: 25852265
Behçet syndrome; Behçet disease; Upper gastrointestinal tract; Inflammatory bowel disease; Lower gastrointestinal tract; Ulcer
8.  A decade of data from a specialist statewide child and adolescent eating disorder service: does local service access correspond with the severity of medical and eating disorder symptoms at presentation? 
Background
Eating disorders affect up to 3% of children and adolescents, with recovery often requiring specialist treatment. A substantial literature has accrued suggesting that lower access to health care services, experienced by rural populations, has a staggering effect on health-related morbidity and mortality. The aim of this study was to evaluate whether lower service access foreshadowed a more severe medical and symptom presentation among children and adolescents presenting to a specialist eating disorders program.
Method
The data source was the Helping to Outline Paediatric Eating Disorders (HOPE) Project registry (N ~1000), a prospective ongoing registry study comprising consecutive paediatric tertiary eating disorder referrals. The sample consisted of 399 children and adolescents aged 8 to 16 years (M =14.49, 92% female) meeting criteria for a DSM-5 eating disorder.
Results
Consistent with the hypotheses, lower service access was associated with a lower body mass index z-score and a higher likelihood of medical complications at intake assessment. Contrary to our hypothesis, eating pathology assessed at intake was associated with higher service access. No relationship was observed between service access and duration of illness or percentage of body weight lost.
Conclusions
Lower service access is associated with more severe malnutrition and medical complications at referral to a specialist eating disorder program. These findings have implications for service planning and provision for rural communities to equalize health outcomes.
doi:10.1186/s40337-014-0032-0
PMCID: PMC4232640  PMID: 25400911
Adolescent; Child; Eating disorders; HOPE Project; Medical complications; Rural
9.  Resolution of Severe Clostridium difficile Infection Following Sequential Fecal Microbiota Transplantation 
doi:10.1097/MCG.0b013e31829004ae
PMCID: PMC3735621  PMID: 23632358
Fecal microbiota transplantation; severe Clostridium difficile infection
10.  Development of Mast Cells and Importance of Their Tryptase and Chymase Serine Proteases in Inflammation and Wound Healing 
Advances in immunology  2014;122:211-252.
Mast cells (MCs) are active participants in blood coagulation and innate and acquired immunity. This review focuses on the development of mouse and human MCs, as well as the involvement of their granule serine proteases in inflammation and the connective tissue remodeling that occurs during the different phases of the healing process of wounded skin and other organs. The accumulated data suggest that MCs, their tryptases, and their chymases play important roles in tissue repair. While MCs initially promote healing, they can be detrimental if they are chronically stimulated or if too many MCs become activated at the same time. The possibility that MCs and their granule serine proteases contribute to the formation of keloid and hypertrophic scars makes them potential targets for therapeutic intervention in the repair of damaged skin.
doi:10.1016/B978-0-12-800267-4.00006-7
PMCID: PMC4115062  PMID: 24507159
11.  A Clinicopathologic Study of 24 Cases of Systemic Mastocytosis Involving the Gastrointestinal Tract and Assessment of Mucosal Mast Cell Density in Irritable Bowel Syndrome and Asymptomatic Patients 
Counting mast cells in gastrointestinal (GI) mucosal biopsies is becoming an increasingly common practice. The primary reason for this exercise is to evaluate for possible involvement by systemic mastocytosis (SM). However, the features of mastocytosis in GI biopsies are not well described. In addition, recent studies have suggested that increased mast cells may be involved in the pathogenesis of some cases of diarrhea-predominant irritable bowel syndrome (IBS); the term “mastocytic enterocolitis” has been proposed for such cases. As the baseline mast cell density in colonic biopsies from normal patients has not been established in large cohorts, there is no widely accepted threshold for what constitutes increased mucosal mast cells. The aims of this study were (1) to determine the utility of GI biopsies for the diagnosis of SM, (2) to characterize the clinical, histologic, and immunohistochemical features of mastocytosis in the GI tract, (3) to determine mast cell density in normal colonic mucosa from a large cohort of asymptomatic patients, and (4) to compare these findings with those from patients with diarrhea-predominant IBS. Twenty-four patients with SM involving the GI tract, 100 asymptomatic patients, and 100 patients with IBS (the latter 2 groups with histologically normal colonic biopsies) were included. For the mastocytosis group, 107 biopsies (70 involved by mastocytosis; 67 mucosal, 3 liver) from 20 women and 4 men were evaluated (median age 59 y). The most commonly involved site was the colon (19 patients, 95%), followed by ileum (86%), duodenum (80%), and stomach (54%). In 16 cases (67%), the first diagnosis of SM was made on the basis of GI biopsies. Seventeen patients had documented cutaneous mastocytosis. Fifteen of 17 patients who underwent bone marrow biopsy had marrow involvement by SM. Eighteen patients had indolent disease, and 6 had aggressive disease (including all 3 with liver involvement). The most common GI symptom was diarrhea, followed by abdominal pain, nausea, weight loss, bloating, vomiting, or reflux. Liver disease presented with hepatomegaly and ascites. Endoscopic abnormalities (observed in 62%) included erythema, granularity, and nodules. Histologically, involved biopsies were characterized by infiltrates of ovoid to spindle-shaped mast cells in aggregates or sheets in the lamina propria, sometimes forming a confluent band underneath the surface epithelium; 25% of biopsies had only focal involvement (single aggregate). Prominent eosinophils were seen in 44% of involved colonic/ileal biopsies and 16% of duodenal biopsies. Mast cells were highlighted by diffuse membranous staining for KIT and CD25. In the nonmastocytosis groups, all biopsies contained singly dispersed mast cells with no aggregates. The mean highest mast cell counts (in a single high-power field) for asymptomatic patients and IBS patients were 26 (range, 11 to 55) and 30 (range, 13 to 59), respectively. In summary, GI (especially colonic) biopsies can establish a diagnosis of SM in patients with GI symptoms. GI involvement is usually subtle and is often associated with prominent eosinophils, which may obscure the mast cell infiltrate. KIT and CD25 are invaluable markers for the diagnosis. Mast cell density in colonic mucosa from asymptomatic patients is highly variable. Although patients with diarrhea-predominant IBS on average have mildly increased mast cells, the overlap in range with that of control patients is too great for this difference to be clinically useful. These findings argue against the utility of counting GI mucosal mast cell in patients with chronic diarrhea.
doi:10.1097/PAS.0000000000000190
PMCID: PMC4086834  PMID: 24618605
gastrointestinal tract; liver; mast cells; mastocytosis; mast cell activation syndrome; irritable bowel syndrome; urticaria pigmentosa; KIT
12.  Species and genus level resolution analysis of gut microbiota in Clostridium difficile patients following fecal microbiota transplantation 
Microbiome  2014;2:13.
Background
Clostridium difficile is an opportunistic human intestinal pathogen, and C. difficile infection (CDI) is one of the main causes of antibiotic-induced diarrhea and colitis. One successful approach to combat CDI, particularly recurrent form of CDI, is through transplantation of fecal microbiota from a healthy donor to the infected patient. In this study we investigated the distal gut microbial communities of three CDI patients before and after fecal microbiota transplantation, and we compared these communities to the composition of the donor’s fecal microbiota. We utilized phylogenetic Microbiota Array, high-throughput Illumina sequencing, and fluorescent in situ hybridization to profile microbiota composition down to the genus and species level resolution.
Results
The original patients’ microbiota had low diversity, was dominated by members of Gammaproteobacteria and Bacilli, and had low numbers of Clostridia and Bacteroidia. At the genus level, fecal samples of CDI patients were rich in members of the Lactobacillus, Streptococcus, and Enterobacter genera. In comparison, the donor community was dominated by Clostridia and had significantly higher diversity and evenness. The patients’ distal gut communities were completely transformed within 3 days following fecal transplantation, and these communities remained stable in each patient for at least 4 months. Despite compositional differences among recipients’ pre-treatment gut microbiota, the transplanted gut communities were highly similar among recipients post-transplantation, were indistinguishable from that of the donor, and were rich in members of Blautia, Coprococcus, and Faecalibacterium. In each case, the gut microbiota restoration led to a complete patient recovery and symptom alleviation.
Conclusion
We conclude that C. difficile infection can be successfully treated by fecal microbiota transplantation and that this leads to stable transformation of the distal gut microbial community from the one abundant in aerotolerant species to that dominated by members of the Clostridia.
doi:10.1186/2049-2618-2-13
PMCID: PMC4030581  PMID: 24855561
Microbiota; Microflora; Clostridium difficile; Fecal microbiota transplantation; Microbiota Array
13.  Restoring the gut microbiome for the treatment of inflammatory bowel diseases 
Fecal microbiota transplantation (FMT) is considered to be a highly successful therapy for recurrent and refractory Clostridium difficile infection (CDI) based on recent clinical trials. The pathogenesis of inflammatory bowel diseases (IBD) is thought to be due in part to perturbations in the gut microflora that disrupt homeostasis. FMT restores essential components of the microflora which could reverse the inflammatory processes observed in IBD. Case reports and series for the treatment of IBD by FMT have shown promise with regards to treatment success and safety despite the limitations of the reporting. Future studies will determine the optimal delivery and preparation of stool as well as the conditions under which the recipient will derive maximal benefit. The long term consequences of FMT with regards to infection, cancer, auto-immune, and metabolic diseases are not known and will require continued regulation and study. Despite these limitations, FMT may be beneficial for the treatment of ulcerative colitis and Crohn’s disease, particularly those with concurrent CDI or with pouchitis.
doi:10.3748/wjg.v20.i13.3468
PMCID: PMC3974513  PMID: 24707129
Crohn’s; Ulcerative colitis; Microbiota; Fecal transplantation; Dysbiosis; Pouchitis; Clostridium difficile; Probiotic
14.  High-throughput DNA sequence analysis reveals stable engraftment of gut microbiota following transplantation of previously frozen fecal bacteria 
Gut Microbes  2013;4(2):125-135.
Fecal microbiota transplantation (FMT) is becoming a more widely used technology for treatment of recurrent Clostridum difficile infection (CDI). While previous treatments used fresh fecal slurries as a source of microbiota for FMT, we recently reported the successful use of standardized, partially purified and frozen fecal microbiota to treat CDI. Here we report that high-throughput 16S rRNA gene sequencing showed stable engraftment of gut microbiota following FMT using frozen fecal bacteria from a healthy donor. Similar bacterial taxa were found in post-transplantation samples obtained from the recipients and donor samples, but the relative abundance varied considerably between patients and time points. Post FMT samples from patients showed an increase in the abundance of Firmicutes and Bacteroidetes, representing 75–80% of the total sequence reads. Proteobacteria and Actinobacteria were less abundant (< 5%) than that found in patients prior to FMT. Post FMT samples from two patients were very similar to donor samples, with the Bacteroidetes phylum represented by a great abundance of members of the families Bacteroidaceae, Rikenellaceae and Porphyromonadaceae, and were largely comprised of Bacteroides, Alistipes and Parabacteroides genera. Members of the phylum Firmicutes were represented by Ruminococcaceae, Lachnospiraceae, Verrucomicrobiaceae and unclassified Clostridiales and members of the Firmicutes. One patient subsequently received antibiotics for an unrelated infection, resulting in an increase in the number of intestinal Proteobacteria, primarily Enterobacteriaceae. Our results demonstrate that frozen fecal microbiota from a healthy donor can be used to effectively treat recurrent CDI resulting in restoration of the structure of gut microbiota and clearing of Clostridum difficile.
doi:10.4161/gmic.23571
PMCID: PMC3595072  PMID: 23333862
fecal microbial transplantation; frozen preparations; DNA sequence analysis; Illumina; microbiota; restoration; Clostridium difficile; firmicutes; bacteroides; curing
15.  Immunology and Clinical Manifestations of Non-Clonal Mast Cell Activation Syndrome 
There is a spectrum of disorders that clinically manifest as a result of mast cell activation. A non-clonal form has emerged in the literature where many of the clinical features of systemic mastocytosis are shared despite having a distinct mast cell biology. In this review, we summarize key features of the science behind mast cell activation relevant to what is now known as non-clonal mast cell activation syndrome (nc-MCAS). We highlight the clinical manifestations of nc-MCAS with a focus on diagnosis and treatment.
doi:10.1007/s11882-012-0326-8
PMCID: PMC3545645  PMID: 23212667
Mast cell activation; Non-clonal mast cell activation syndrome; Tryptase; Prostaglandin; Histamine; cKIT; Flushing; Anaphylaxis; Antihistamines; Immunology
16.  Chemical Variation in a Dominant Tree Species: Population Divergence, Selection and Genetic Stability across Environments 
PLoS ONE  2013;8(3):e58416.
Understanding among and within population genetic variation of ecologically important plant traits provides insight into the potential evolutionary processes affecting those traits. The strength and consistency of selection driving variability in traits would be affected by plasticity in differences among genotypes across environments (G×E). We investigated population divergence, selection and environmental plasticity of foliar plant secondary metabolites (PSMs) in a dominant tree species, Eucalyptus globulus. Using two common garden trials we examined variation in PSMs at multiple genetic scales; among 12 populations covering the full geographic range of the species and among up to 60 families within populations. Significant genetic variation in the expression of many PSMs resides both among and within populations of E. globulus with moderate (e.g., sideroxylonal A h2op = 0.24) to high (e.g., macrocarpal G h2op = 0.48) narrow sense heritabilities and high coefficients of additive genetic variation estimated for some compounds. A comparison of Qst and Fst estimates suggest that variability in some of these traits may be due to selection. Importantly, there was no genetic by environment interaction in the expression of any of the quantitative chemical traits despite often significant site effects. These results provide evidence that natural selection has contributed to population divergence in PSMs in E. globulus, and identifies the formylated phloroglucinol compounds (particularly sideroxylonal) and a dominant oil, 1,8-cineole, as candidates for traits whose genetic architecture has been shaped by divergent selection. Additionally, as the genetic differences in these PSMs that influence community phenotypes is stable across environments, the role of plant genotype in structuring communities is strengthened and these genotypic differences may be relatively stable under global environmental changes.
doi:10.1371/journal.pone.0058416
PMCID: PMC3603948  PMID: 23526981
17.  The Valuable Role of Endoscopy in Inflammatory Bowel Disease 
Endoscopy is a valuable clinical tool for the clinician who takes care of patients with inflammatory bowel disease (IBD). The role of endoscopy in the diagnosis, management, and treatment of IBD is discussed in this review. The central role that colonoscopy plays in screening for colon cancer in patients with longstanding IBD is also addressed.
doi:10.1155/2012/467979
PMCID: PMC3299364  PMID: 22474403
18.  Large Scale Analysis of Virulence Genes in Escherichia coli Strains Isolated from Avalon Bay, CA 
Water research  2010;44(18):5463-5473.
Contamination of recreational waters with E. coli and Enterococcus sp. is a widespread problem resulting in beach closures and loss of recreational activity. While E. coli is frequently used as an indicator of fecal contamination, and has been extensively measured in waterways, few studies have examined the presence of potentially pathogenic E. coli strains in beach waters. In this study, a combination of high-throughput, robot-assisted colony hybridization and PCR-based analyses were used to determine the genomic composition and frequency of virulence genes present in E. coli isolated from beach water in Avalon Bay, Santa Catalina Island, CA. A total of 24,493 E. coli isolates were collected from two sites at a popular swimming beach between August through September 2007 and from July through August 2008. All isolates were examined for the presence of shiga-like toxins (stx1/stx2), intimin (eaeA), and enterotoxins (ST/LT). Of the 24,493 isolates examined, 3.6% contained the eaeA gene, indicating that these isolates were potential EPEC strains. On five dates, however, greater than 10% of the strains were potential EPEC, suggesting that incidence of virulence genes at this beach has a strong temporal component. No STEC or ETEC isolates were detected, and only eight (<1.0%) of the potential EPEC isolates were found to carry the EAF plasmid. The potential EPEC isolates mainly belonged to E. coli phylogenetic groups B1 or B2, and carried the beta intimin subtype. DNA fingerprint analyses of the potential EPEC strains indicated that the isolates belonged to several genetically diverse groups, although clonal isolates were frequently detected. While the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potential EPEC strains can be found in marine beach water and their presence needs to be considered as one of the factors used in decisions concerning beach closures.
doi:10.1016/j.watres.2010.06.058
PMCID: PMC2952692  PMID: 20643468
Bacteria; E. coli; Beach water; virulence genes; phylogenetic groups; DNA fingerprinting
19.  Reconsidering the generation time hypothesis based on nuclear ribosomal ITS sequence comparisons in annual and perennial angiosperms 
Background
Differences in plant annual/perennial habit are hypothesized to cause a generation time effect on divergence rates. Previous studies that compared rates of divergence for internal transcribed spacer (ITS1 and ITS2) sequences of nuclear ribosomal DNA (nrDNA) in angiosperms have reached contradictory conclusions about whether differences in generation times (or other life history features) are associated with divergence rate heterogeneity. We compared annual/perennial ITS divergence rates using published sequence data, employing sampling criteria to control for possible artifacts that might obscure any actual rate variation caused by annual/perennial differences.
Results
Relative rate tests employing ITS sequences from 16 phylogenetically-independent annual/perennial species pairs rejected rate homogeneity in only a few comparisons, with annuals more frequently exhibiting faster substitution rates. Treating branch length differences categorically (annual faster or perennial faster regardless of magnitude) with a sign test often indicated an excess of annuals with faster substitution rates. Annuals showed an approximately 1.6-fold rate acceleration in nucleotide substitution models for ITS. Relative rates of three nuclear loci and two chloroplast regions for the annual Arabidopsis thaliana compared with two closely related Arabidopsis perennials indicated that divergence was faster for the annual. In contrast, A. thaliana ITS divergence rates were sometimes faster and sometimes slower than the perennial. In simulations, divergence rate differences of at least 3.5-fold were required to reject rate constancy in > 80 % of replicates using a nucleotide substitution model observed for the combination of ITS1 and ITS2. Simulations also showed that categorical treatment of branch length differences detected rate heterogeneity > 80% of the time with a 1.5-fold or greater rate difference.
Conclusion
Although rate homogeneity was not rejected in many comparisons, in cases of significant rate heterogeneity annuals frequently exhibited faster substitution rates. Our results suggest that annual taxa may exhibit a less than 2-fold rate acceleration at ITS. Since the rate difference is small and ITS lacks statistical power to reject rate homogeneity, further studies with greater power will be required to adequately test the hypothesis that annual and perennial plants have heterogeneous substitution rates. Arabidopsis sequence data suggest that relative rate tests based on multiple loci may be able to distinguish a weak acceleration in annual plants. The failure to detect rate heterogeneity with ITS in past studies may be largely a product of low statistical power.
doi:10.1186/1471-2148-8-344
PMCID: PMC2637270  PMID: 19113991
20.  High-Throughput and Quantitative Procedure for Determining Sources of Escherichia coli in Waterways by Using Host-Specific DNA Marker Genes▿  
Escherichia coli is currently used as an indicator of fecal pollution and to assess water quality. While several genotypic techniques have been used to determine potential sources of fecal bacteria impacting waterways and beaches, they do not allow for the rapid analysis of a large number of samples in a relatively short period of time. Here we report that gene probes identified by Hamilton and colleagues (M. J. Hamilton, T. Yan, and M. J. Sadowsky, Appl. Environ. Microbiol. 72:4012-4019, 2006) were useful for the development of a high-throughput and quantitative macroarray hybridization system to determine numbers of E. coli bacteria originating from geese/ducks. The procedure we developed, using a QBot robot for picking and arraying of colonies, allowed us to simultaneously analyze up to 20,736 E. coli colonies from water samples, with minimal time and human input. Statistically significant results were obtained by analyzing 700 E. coli colonies per water sample, allowing for the analysis of approximately 30 sites per macroarray. Macroarray hybridization studies done on E. coli collected from water samples obtained from two urban Minnesota lakes and one rural South Carolina lake indicated that geese/ducks contributed up to 51% of the fecal bacteria in the urban lake water samples, and the level was below the detection limit in the rural lake water sample. This technique, coupled with the use of other host source-specific gene probes, holds great promise as a new quantitative microbial source tracking tool to rapidly determine the origins of E. coli in waterways and on beaches.
doi:10.1128/AEM.01395-06
PMCID: PMC1800753  PMID: 17158618
21.  Development of Goose- and Duck-Specific DNA Markers To Determine Sources of Escherichia coli in Waterways 
The contamination of waterways with fecal material is a persistent threat to public health. Identification of the sources of fecal contamination is a vital component for abatement strategies and for determination of total maximum daily loads. While phenotypic and genotypic techniques have been used to determine potential sources of fecal bacteria in surface waters, most methods require construction of large known-source libraries, and they often fail to adequately differentiate among environmental isolates originating from different animal sources. In this study, we used pooled genomic tester and driver DNAs in suppression subtractive hybridizations to enrich for host source-specific DNA markers for Escherichia coli originating from locally isolated geese. Seven markers were identified. When used as probes in colony hybridization studies, the combined marker DNAs identified 76% of the goose isolates tested and cross-hybridized, on average, with 5% of the human E. coli strains and with less than 10% of the strains obtained from other animal hosts. In addition, the combined probes identified 73% of the duck isolates examined, suggesting that they may be useful for determining the contribution of waterfowl to fecal contamination. However, the hybridization probes reacted mainly with E. coli isolates obtained from geese in the upper midwestern United States, indicating that there is regional specificity of the markers identified. Coupled with high-throughput, automated macro- and microarray screening, these markers may provide a quantitative, cost-effective, and accurate library-independent method for determining the sources of genetically diverse E. coli strains for use in source-tracking studies. However, future efforts to generate DNA markers specific for E. coli must include isolates obtained from geographically diverse animal hosts.
doi:10.1128/AEM.02764-05
PMCID: PMC1489605  PMID: 16751510
22.  Effective killing of the human pathogen Candida albicans by a specific inhibitor of non-essential mitotic kinesin Kip1p 
Molecular Microbiology  2007;65(2):347-362.
Kinesins from the bipolar (Kinesin-5) family are conserved in eukaryotic organisms and play critical roles during the earliest stages of mitosis to mediate spindle pole body separation and formation of a bipolar mitotic spindle. To date, genes encoding bipolar kinesins have been reported to be essential in all organisms studied. We report the characterization of CaKip1p, the sole member of this family in the human pathogenic yeast Candida albicans. C. albicans Kip1p appears to localize to the mitotic spindle and loss of CaKip1p function interferes with normal progression through mitosis. Inducible excision of CaKIP1 revealed phenotypes unique to C. albicans, including viable homozygous Cakip1 mutants and an aberrant spindle morphology in which multiple spindle poles accumulate in close proximity to each other. Expression of the C. albicans Kip1 motor domain in Escherichia coli produced a protein with microtubule-stimulated ATPase activity that was inhibited by an aminobenzothiazole (ABT) compound in an ATP-competitive fashion. This inhibition results in ‘rigor-like’, tight association with microtubules in vitro. Upon treatment of C. albicans cells with the ABT compound, cells were killed, and terminal phenotype analysis revealed an aberrant spindle morphology similar to that induced by loss of the CaKIP1 gene. The ABT compound discovered is the first example of a fungal spindle inhibitor targeted to a mitotic kinesin. Our results also show that the non-essential nature and implementation of the bipolar motor in C. albicans differs from that seen in other organisms, and suggest that inhibitors of a non-essential mitotic kinesin may offer promise as cidal agents for antifungal drug discovery.
doi:10.1111/j.1365-2958.2007.05787.x
PMCID: PMC1976386  PMID: 17573815

Results 1-22 (22)