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UFGI publication round-up week 5/15/17

A Highly Potent Class of Halogenated Phenazine Antibacterial and Biofilm-Eradicating Agents Accessed Through a Modular Wohl-Aue Synthesis.

Author information: Yang H1, Abouelhassan Y1, Burch GM1, Kallifidas D1, Huang G2, Yousaf H1, Jin S2, Luesch H1, Huigens RW3.

1Department of Medicinal Chemistry, Center for Natural Products Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, 1345 Center Dr., Gainesville, FL, 32610, USA.
2Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, 1200 Newell Drive, Gainesville, FL, 32610, USA.
3Department of Medicinal Chemistry, Center for Natural Products Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, 1345 Center Dr., Gainesville, FL, 32610, USA. rhuigens@cop.ufl.edu.
Journal: Scientific Reports

Date of e-pub: May 2017

Abstract: Unlike individual, free-floating planktonic bacteria, biofilms are surface-attached communities of slow- or non-replicating bacteria encased within a protective extracellular polymeric matrix enabling persistent bacterial populations to tolerate high concentrations of antimicrobials. Our current antibacterial arsenal is composed of growth-inhibiting agents that target rapidly-dividing planktonic bacteria but not metabolically dormant biofilm cells. We report the first modular synthesis of a library of 20 halogenated phenazines (HP), utilizing the Wohl-Aue reaction, that targets both planktonic and biofilm cells. New HPs, including 6-substituted analogues, demonstrate potent antibacterial activities against MRSA, MRSE and VRE (MIC = 0.003-0.78 µM). HPs bind metal(II) cations and demonstrate interesting activity profiles when co-treated in a panel of metal(II) cations in MIC assays. HP 1 inhibited RNA and protein biosynthesis while not inhibiting DNA biosynthesis using 3H-radiolabeled precursors in macromolecular synthesis inhibition assays against MRSA. New HPs reported here demonstrate potent eradication activities (MBEC = 0.59-9.38 µM) against MRSA, MRSE and VRE biofilms while showing minimal red blood cell lysis or cytotoxicity against HeLa cells. PEG-carbonate HPs 24 and 25 were found to have potent antibacterial activities with significantly improved water solubility. HP small molecules could have a dramatic impact on persistent, biofilm-associated bacterial infection treatments.

 

 

LdtR is a master regulator of gene expression in Liberibacter asiaticus.

Author information: Pagliai FA1, Coyle JF1, Kapoor S1, Gonzalez CF1, Lorca GL1.

1Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA.
Journal: Microbial Biotechnology

Date of e-pub: May 2017

Abstract: Huanglongbing or citrus greening disease is causing devastation to the citrus industry. Liberibacter asiaticus, an obligate intracellular pathogen of citrus, is one the causative agents of the disease. Most of the knowledge about this bacterium has been deduced from the in silico exploration of its genomic sequence. L. asiaticus differentially expresses genes during its transmission from the psyllid vector, Diaphorina citri, to the plant. However, the regulatory mechanisms for the adaptation of the bacterium into either hosts remain unknown. Here we show that LdtR, a MarR family transcriptional regulator, activates or represses transcription genome-wide. We performed a double approach to identify the components of the LdtR regulon: a transcriptome analysis in both the related bacterium Liberibacter crescens and citrus-infected leaves, strengthened with an in silico prediction of LdtR regulatory sites. Our results demonstrated that LdtR controls the expression of nearly 180 genes in L. asiaticus, distributed in processes such as cell motility, cell wall biogenesis, energy production, and transcription. These results provide new evidence about the regulatory network of L. asiaticus, where the differential expression of genes from these functional categories could be of great importance during the adaptation of the bacterium to either hosts.

 

 

How Does Reference Site Selection Influence Interpretation of Omics Data?: Evaluating Liver Transcriptome Responses in Male Rainbow Darter (Etheostoma caeruleum) across an Urban Environment.

Author information: Marjan P1, Bragg LM1, MacLatchy DL2, Servos MR1, Martyniuk CJ3.

1Department of Biology, University of Waterloo , 200 University Avenue West, N2L 3G1 Waterloo, Ontario, Canada.
2Department of Biology, Wilfrid Laurier University , 75 University Avenue West, N2L 3C5 Waterloo, Ontario, Canada.
3Center for Environmental and Human Toxicology & Department of Physiological Sciences, University of Florida , 2187 Mowry Road, Building 471, PO Box 110885, Gainesville, Florida 32611, United States.
Journal: Environmental Science & Technology

Date of e-pub: May 2017

Abstract: Studies quantifying the influence of reference site selection on transcriptomic profiles in aquatic organisms exposed to complex mixtures are lacking in the literature, despite the significant implications of such research for the interpretation of omics data sets. We measured hepatic transcriptomic responses in fish across an urban environment in the central Grand River watershed (Ontario, Canada). Adult male rainbow darter (RBD) (Etheostoma caeruleum) were collected from nine sites at varying distances from two major municipal wastewater treatment plants (MWWTPs) (Waterloo, Kitchener), including three upstream reference sites. The transcriptomic response in RBD was independently compared with that of fish from each of the three reference sites. Data collected in fish downstream of the Waterloo MWWTP (poorest effluent quality) suggested that ∼15.5% of the transcriptome response was influenced by reference site selection. In contrast, at sites where the impact of MWWTPs was less-pronounced and fish showed less of a transcriptome response, reference site selection had a greater influence (i.e., ∼56.9% of transcripts were different depending on the site used). This study highlights the importance of conducting transcriptomics studies that leverage more than one reference site, and it broadens our understanding of the molecular responses in fish in dynamic natural environments.

 

 

How do seemingly non-vagile clades accomplish trans-marine dispersal? Trait and dispersal evolution in the landfowl (Aves: Galliformes).

Author information: Hosner PA1,2, Tobias JA3, Braun EL4, Kimball RT4.

1Department of Biology, University of Florida, Gainesville, FL, USA hosner@ufl.edu.
2Florida Museum of Natural History, University of Florida, Gainesville, FL, USA.
3Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK.
4Department of Biology, University of Florida, Gainesville, FL, USA.
Journal: Proceedings. Biological Sciences

Date of e-pub: May 2017

Abstract: Dispersal ability is a key factor in determining insular distributions and island community composition, yet non-vagile terrestrial organisms widely occur on oceanic islands. The landfowl (pheasants, partridges, grouse, turkeys, quails and relatives) are generally poor dispersers, but the Old World quail (Coturnix) are a notable exception. These birds evolved small body sizes and high-aspect-ratio wing shapes, and hence are capable of trans-continental migrations and trans-oceanic colonization. Two monotypic partridge genera, Margaroperdix of Madagascar and Anurophasis of alpine New Guinea, may represent additional examples of trans-marine dispersal in landfowl, but their body size and wing shape are typical of poorly dispersive continental species. Here, we estimate historical relationships of quail and their relatives using phylogenomics, and infer body size and wing shape evolution in relation to trans-marine dispersal events. Our results show that Margaroperdix and Anurophasis are nested within the Coturnix quail, and are each ‘island giants’ that independently evolved from dispersive, Coturnix-like ancestral populations that colonized and were subsequently isolated on Madagascar and New Guinea. This evolutionary cycle of gain and loss of dispersal ability, coupled with extinction of dispersive taxa, can result in the false appearance that non-vagile taxa somehow underwent rare oceanic dispersal.

 

 

Locoregional Effects of Microbiota in a Preclinical Model of Colon Carcinogenesis.

Author information: Tomkovich S1,2, Yang Y1, Winglee K3, Gauthier J1, Mühlbauer M1, Sun X1, Mohamadzadeh M4, Liu X5, Martin P6,7, Wang GP8, Oswald E6,7, Fodor AA3, Jobin C9,4.

1Department of Medicine, University of Florida, Gainesville, Florida.
2 Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
3Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, North Carolina.
4Department of Infectious Diseases and Pathology, University of Florida, Gainesville, Florida.
5Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida.
6IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France.
7CHU Toulouse, Service de Bactériologie-Hygiène, Toulouse, France.
8Department of Medicine, Division of Infectious Diseases and Global Medicine, University of Florida, Gainesville, Florida.
9Department of Medicine, University of Florida, Gainesville, Florida. Christian.Jobin@medicine.ufl.edu.
Journal: Cancer Research

Date of e-pub: May 2017

Abstract: nflammation and microbiota are critical components of intestinal tumorigenesis. To dissect how the microbiota contributes to tumor distribution, we generated germ-free (GF) ApcMin/+ and ApcMin/+ ;Il10-/- mice and exposed them to specific-pathogen-free (SPF) or colorectal cancer-associated bacteria. We found that colon tumorigenesis significantly correlated with inflammation in SPF-housed ApcMin/+ ;Il10-/- , but not in ApcMin/+ mice. In contrast, small intestinal neoplasia development significantly correlated with age in both ApcMin/+ ;Il10-/- and ApcMin/+ mice. GF ApcMin/+ ;Il10-/- mice conventionalized by an SPF microbiota had significantly more colon tumors compared with GF mice. Gnotobiotic studies revealed that while Fusobacterium nucleatum clinical isolates with FadA and Fap2 adhesins failed to induce inflammation and tumorigenesis, pks+Escherichia coli promoted tumorigenesis in the ApcMin/+ ;Il10-/- model in a colibactin-dependent manner, suggesting colibactin is a driver of carcinogenesis. Our results suggest a distinct etiology of cancers in different locations of the gut, where colon cancer is primarily driven by inflammation and the microbiome, while age is a driving force for small intestine cancer. Cancer Res; 77(10); 2620-32. ©2017 AACR.

 

 

Arsenic-hyperaccumulator Pteris vittata efficiently solubilized phosphate rock to sustain plant growth and As uptake.

Author information: Fu JW1, Liu X1, Han YH1, Mei H2, Cao Y1, de Oliveira LM3, Liu Y4, Rathinasabapathi B5, Chen Y6, Ma LQ7.

1State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.
2State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China; Faculty of Environmental Science and Engineering, South West Forestry University, Yunnan 650224, China.
3Soil and Water Science Department, University of Florida, Gainesville, FL 32611, United States.
4Faculty of Environmental Science and Engineering, South West Forestry University, Yunnan 650224, China.
5Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, United States.
6State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China. Electronic address: chenyanshan@nju.edu.cn.
7State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China; Soil and Water Science Department, University of Florida, Gainesville, FL 32611, United States. Electronic address: lqma@ufl.edu.
Journal: Journal of Hazardous Materials

Date of e-pub: May 2017

Abstract: Phosphorus (P) is one of the most important nutrients for phytoremediation of arsenic (As)-contaminated soils. In this study, we demonstrated that As-hyperaccumulator Pteris vittata was efficient in acquiring P from insoluble phosphate rock (PR). When supplemented with PR as the sole P source in hydroponic systems, P. vittata accumulated 49% and 28% higher P in the roots and fronds than the -P treatment. In contrast, non-hyperaccumulator Pteris ensiformis was unable to solubilize P from PR. To gain insights into PR solubilization by plants, organic acids in plant root exudates were analyzed by HPLC. The results showed that phytic acid was the predominant (>90%) organic acid in P. vittata root exudates whereas only oxalic acid was detected in P. ensiformis. Moreover, P. vittata secreted more phytic acid in -P and PR treatments. Compared to oxalic acid, phytic acid was more effective in solubilizing PR, suggesting that phytic acid was critical for PR utilization. Besides, secretion of phytic acid by P. vittata was not inhibited by arsenate. Our data indicated that phytic acid played an important role in efficient use of insoluble PR by P. vittata, shedding light on using insoluble PR to enhance phytoremediation of As-contaminated soils.

 

NOTE: These abstracts were retrieved from the U.S. National Library of Medicine website managed in collaboration with the U.S. National Library of Medicine

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