Artículos
https://hdl.handle.net/2238/11156
2024-03-28T17:42:49ZIdentification of the agr Peptide of Listeria monocytogenes
https://hdl.handle.net/2238/9957
Identification of the agr Peptide of Listeria monocytogenes
Zetzmann, Marion; Sánchez-Kopper, Andrés; Waidmann, Mark; Blombach, Bastian; Riede, Christian
Listeria monocytogenes (Lm) is an important food-borne human pathogen that is able
to strive under a wide range of environmental conditions. Its accessory gene regulator
(agr) system was shown to impact on biofilm formation and virulence and has been
proposed as one of the regulatory mechanisms involved in adaptation to these changing
environments. The Lm agr operon is homologous to the Staphylococcus aureus system,
which includes an agrD-encoded autoinducing peptide that stimulates expression of the
agr genes via the AgrCA two-component system and is required for regulation of target
genes. The aim of the present study was to identify the native autoinducing peptide (AIP)
of Lm using a luciferase reporter system in wildtype and agrD deficient strains, rational
design of synthetic peptides and mass spectrometry. Upon deletion of agrD, luciferase
reporter activity driven by the PII promoter of the agr operon was completely abolished
and this defect was restored by co-cultivation of the agrD-negative reporter strain with
a producer strain. Based on the sequence and structures of known AIPs of other
organisms, a set of potential Lm AIPs was designed and tested for PII-activation. This led
to the identification of a cyclic pentapeptide that was able to induce PII-driven luciferase
reporter activity and restore defective invasion of the agrD deletion mutant into Caco-
2 cells. Analysis of supernatants of a recombinant Escherichia coli strain expressing
AgrBD identified a peptide identical in mass and charge to the cyclic pentapeptide. The
Lm agr system is specific for this pentapeptide since the AIP of Lactobacillus plantarum,
which also is a pentapeptide yet with different amino acid sequence, did not induce PII
activity. In summary, the presented results provide further evidence for the hypothesis
that the agrD gene of Lm encodes a secreted AIP responsible for autoregulation
Artículo científico
2016-01-01T00:00:00ZTowards autotrophic tissue engineering: photosynthetic gene therapy for regeneration
https://hdl.handle.net/2238/9849
Towards autotrophic tissue engineering: photosynthetic gene therapy for regeneration
Chávez, Myra Noemi; Ludwig-Schenck, Thilo; Hopfner, Ursula; Centeno-Cerdas, Carolina; Somlai-Schweiger, Ian; Schwarz, Christian; Machens, Hans-Günther; Heikenwalder, Mathias; Bono, María Rosa; Allende, Miguel; Nickelsen, Jörg; Egaña, José Tomás
The use of artificial tissues in regenerative medicine is limited due to hypoxia. As a strategy to overcome this drawback, we have shown that photosynthetic biomaterials can produce and provide oxygen independently of blood perfusion by generating chimeric animal-plant tissues during dermal regeneration. In this work, we demonstrate the safety and efficacy of photosynthetic biomaterials in vivo after engraftment in a fully immunocompetent mouse skin defect model. Further, we show that it is also possible to genetically engineer such photosynthetic scaffolds to deliver other key molecules in addition to oxygen. As a proof-of-concept, biomaterials were loaded with gene modified microalgae expressing the angiogenic recombinant protein VEGF. Survival of the algae, growth factor delivery and regenerative potential were evaluated in vitro and in vivo. This work proposes the use of photosynthetic gene therapy in regenerative medicine and provides scientific evidence for the use of engineered microalgae as an alternative to deliver recombinant molecules for gene therapy.
Artículo científico
2016-01-01T00:00:00ZScientometric analysis of Colombian research on bio-inoculants for agricultural production
https://hdl.handle.net/2238/9834
Scientometric analysis of Colombian research on bio-inoculants for agricultural production
Zambrano-Moreno, Diana; Avellaneda-Franco, Laura; Zambrano, Gregorio; Bonilla-Buitrago, Ruth
The excessive use of synthetic chemical inputs in agricultural production has led to the disruption of biogeochemical cycles. One of the alternatives that arose within the systems of sustainable agriculture was the partial or total replacement of chemicals by biological substances. The analysis of relevant scientific literature has become a tool for assessing the quality of knowledge generation and its impact on the environment. A scientometric analysis was conducted of Colombian research on bio-inoculants from 2009 through 2014 in journals added to the Web of SciencesTM in order to identify the characteristics of the main target crops, the microorganisms used, and the beneficial effects on agriculture. In this work, 34 articles were identified: 24 (71 %) were research on bio-fertilizer development and 10 (29 %) on bio-pesticides. Articles mainly focused on the study of Gram-negative bacilli affecting the area (77 %), while others focused on issues and topics surrounding vegetables (30 %).The analysis of co-occurrence of keywords identified: i. several genera of microorganisms (e.g. Azotobacter sp., Bradyrhizobium sp.) and sustainable agriculture as issues that have a leading role in this scientific field, ii. plant growth promoting rhizobacteria (PGPR) as an emerging issue, iii. biological nitrogen fixation (BNF) as a subject which has risen in a complementary manner and iv. endophytic bacteria and biodiversity as issues in growth. This study showed that research in Colombia could be targeted on issues such as endophytic bacteria, diversity and productivity.
Artículo científico
2016-01-01T00:00:00ZMolecular identification of Trichoderma spp. in garlic and onion fields and In Vitro antagonism trials on Sclerotium cepivorum
https://hdl.handle.net/2238/9810
Molecular identification of Trichoderma spp. in garlic and onion fields and In Vitro antagonism trials on Sclerotium cepivorum
Alvarado-Marchena, Luis; Rivera-Méndez, William
Trichoderma species are non-pathogenic microorganisms that protect against fungal diseases and contribute to increased crop yields. However, not all Trichoderma species have the same effects on crop or a pathogen, whereby the characterization and identification of strains at the species level is the first step in the use of a microorganism. The aim of this study was the identification – at species level – of five strains of Trichoderma isolated from soil samples obtained from garlic and onion fields located in Costa Rica, through the analysis of the ITS1, 5.8S, and ITS2 ribosomal RNA regions; as well as the determination of their individual antagonistic ability over S. cepivorum Berkeley. In order to distinguish the strains, the amplified products were analyzed using MEGA v6.0 software, calculating the genetic distances through the Tamura-Nei model and building the phylogenetic tree using the Maximum Likelihood method. We established that the evaluated strains belonged to the species T. harzianum and T. asperellum; however it was not possible to identify one of the analyzed strains based on the species criterion. To evaluate their antagonistic ability, the dual culture technique, Bell’s scale, and the percentage inhibition of radial growth (PIRG) were used, evidencing that one of the T. asperellum isolates presented the best yields under standard, solid fermentation conditions.
Artículo científico
2016-01-01T00:00:00Z