ABSTRACT
Pseudomonas aeruginosa plasmid pUM505 possesses a pathogenicity island that contains the pumAB genes that encode products with sequence similarity to Toxin-Antitoxin (TA) modules. RT-PCR assays on the overlapping regions of the pumAB genes generated a bicistronic messenger RNA, suggesting that they form an operon. When the pumAB genes were cloned into the pJET vector, recombinant plasmid pJET-pumAB was maintained under nonselective conditions in Escherichia coli cells after six daily subcultures, whereas pJET without pumAB genes was lost. These data indicate that pumAB genes confer post-segregational plasmid stability. In addition, overexpression of the PumA protein in the E. coli BL21 strain resulted in a significant growth inhibition, while BL21 co-expressing the PumA and PumB proteins did not show growth inhibition. These results indicate that pumAB genes encode a TA system where the PumB protein counters the toxic effects of the PumA toxin. Furthermore, P. aeruginosa PAO1 transformants with the pumA gene increased Caenorhabditis elegans and mouse mortality rate and improved mouse organ invasion, effects neutralized by the PumB protein. Moreover, purified recombinant His-PumA protein decreased the viability of C. elegans, indicating that the PumA protein could acts as a toxin. These results indicate that PumA has the potential to promoter the PAO1 virulence against C. elegans and mice when is expressed in absence of PumB. This is the first description, to our knowledge, of a plasmid-encoded TA system that confers plasmid stability and encoded a toxin with the possible ability to increase the P. aeruginosa virulence.
Subject(s)
Bacterial Toxins/genetics , Bacterial Toxins/toxicity , Genes, Bacterial/genetics , Plasmids/genetics , Pseudomonas aeruginosa/genetics , Toxin-Antitoxin Systems/genetics , Virulence Factors/genetics , Animals , Antitoxins/genetics , Bacterial Proteins/genetics , Base Sequence , Caenorhabditis elegans/drug effects , Disease Models, Animal , Escherichia coli/drug effects , Escherichia coli/genetics , Escherichia coli/growth & development , Gene Expression Regulation, Bacterial , Genetic Vectors , Male , Mice , Mice, Inbred BALB C , Operon/genetics , Pseudomonas Infections/microbiology , Pseudomonas Infections/mortality , Pseudomonas aeruginosa/pathogenicity , RNA, Bacterial/analysis , Recombinant Proteins/genetics , Sequence Analysis , Virulence/geneticsABSTRACT
The pUM505 plasmid was isolated from a clinical strain of Pseudomonas aeruginosa. This plasmid contains a genomic island with sequence similar to islands found in chromosomes of virulent P. aeruginosa clinical isolates. The objective of this work was to determine whether pUM505 increases the virulence of P. aeruginosa and to identify the genes responsible for this property. First, using the lettuce-leaf model, we found that pUM505 significantly increases the virulence of P. aeruginosa reference strain PAO1. pUM505 also increased the PAO1 virulence in a murine model and increased cytotoxicity of this strain toward HeLa cells. Thus, we generated a pUM505 gene library of 103 clones in the pUCP20 binary vector. The library was transferred to Escherichia coli TOP10 and P. aeruginosa PAO1 to identify genes. The lettuce-leaf model allowed us to identify three recombinant plasmids that increased the virulence of both E. coli and P. aeruginosa strains. These recombinant plasmids also increased the virulence of the PAO1 strain in mice and induced a cytotoxic effect in HeLa cells. Eleven genes were identified in the virulent transformants. Of these genes, only the pUM505 ORF 2 has homology with a gene previously implicated in virulence. These results indicate that pUM505 contains several genes that encode virulence factors, suggesting that the plasmid may contribute directly to bacterial virulence.
Subject(s)
Genes, Bacterial , Plasmids/genetics , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/pathogenicity , Animals , Cell Line , Cell Survival , Disease Models, Animal , Gene Library , Humans , Lactuca/microbiology , Male , Mice , Plant Diseases/microbiology , Plant Leaves/microbiology , Pseudomonas Infections/microbiology , Pseudomonas Infections/mortality , Virulence/geneticsABSTRACT
In Colombia, like most Neotropical countries, faunistic studies on flower flies have been occasional and most of them have been primarily focused on taxonomy. Colombia is the second-most species-rich country in flower fly diversity in the Neotropics after Brazil, and has one of the highest numbers of species per unit area (2.49 per 10,000 km²), based on a review of literature and national collections. Including new data presented here, a total of 47 genera and 300 species are recorded in Colombia. The genera Scaeva Fabricius and Lycastrirhyncha Bigot, as well as 101 species are recorded here for the first time. The altitudinal range and the distribution of the flower fly genera in Colombia are presented. A preliminary comparison of the fauna of Colombia with that of other Neotropical countries is given. A historical perspective is also provided in order to illustrate how Colombian Syrphidae knowledge has progressed over the last 168 years. Information presented here will be useful for ongoing and future biodiversity research as well as conservation projects on Syrphidae in the Neotropical region.
Subject(s)
Diptera , Animals , Colombia , Demography , FlowersABSTRACT
Objetivo: Demostrar la existencia de una relación entre el espesor corneal central y los pacientes diabéticos. Métodos: Se utilizó un paquímetro ultrasónico para medir el espesor corneal en 1000 pacientes. Dividimos los pacientes en dos grupos: 953 no diabéticos y 47 pacientes diabéticos. Resultados: La paquimetría central media encontrada en los pacientes diabéticos fue 571,96 ± 26,81 micras con un rango comprendido entre 514 y 626. La paquimetría central media hallada en el grupo de no diabéticos fue 544,89 ± 35,36 micras con un rango desde 448 hasta 649. Encontramos un aumento del espesor corneal central estadísticamente significativo (p<0,001, test «t» student) en el grupo de pacientes diabéticos al compararlos con los no diabéticos. Conclusiones: Hemos encontrado que los pacientes diabéticos presentan un espesor corneal central medio mayor frente a los pacientes no diabéticos
Objective: To prove the existence of a correlation between central corneal thickness and diabetes. Methods: Ultrasound pachymetry measurements were made in 1,000 patients. The sample was divided into two groups of patients: 953 of them were non-diabetic patients, and 47 were diabetic patients. Results: The average central corneal thickness in diabetic patients was 571.96 ± 26.81 microns with a range between 514 and 626. The average central corneal thickness found in non-diabetic patients was 544.89 ± 35.36 microns with range of 448 to 649. The increase in central corneal thickness found in diabetic patients compared to non-diabetic patients was statistically significant (p<0.001, Student «t» test). Conclusions: We found that diabetic patients had an increased central corneal thickness when compared with non-diabetic patients
