BackgroundAntimicrobial peptides (AMPs) are the first line of host immune defense against pathogens. Among AMPs from the honeybee Apis mellifera, abaecin is a major broad-spectrum antibacterial proline-enriched cationic peptide.ResultsFor heterologous expression of abaecin in Pichia pastoris, we designed an ORF with HisTag, and the codon usage was optimized. The gene was chemically synthetized and cloned in the pUC57 vector. The new ORF was sub-cloned in the pPIC9 expression vector and transformed into P. pastoris. After selection of positive clones, the expression was induced by methanol. The supernatant was analyzed at different times to determine the optimal time for the recombinant peptide expression. As a proof-of-concept, Escherichia coli was co-incubated with the recombinant peptide to verify its antimicrobial potential.DiscussionBriefly, the recombinant Abaecin (rAbaecin) has efficiently decreased E. coli growth (P < 0.05) through an in vitro assay, and may be considered as a novel therapeutic agent that may complement other conventional antibiotic therapies.

Tollip plays an important role in the interleukin-1 receptor IL-1R and Toll pathways. As a modulator of the immune pathway, it indirectly controls the amount of antimicrobial peptides. This could indicate a vital step in maintaining animal immune systems and preventing infection. Evolutionary questions are crucial to understanding the conservation and functioning of the biochemical pathways like the Tollip-mediated one. Through an analysis of 36 sequences of the Tollip protein from different animal taxa, downloaded from Kyoto Encyclopedia of Genes and Genomes (KEGG) databank, we inferred diverse evolutionary parameters, such as molecular selection and structure conservation, by analyzing residue by residue, beyond the canonical parameters to this type of study, as maximum likelihood trees. We found that Tollip presented different trends in its evolving history. In primates, the protein is becoming more unstable, just the opposite is observed in the arthropod group. The most interesting finding was the concentration of positively selected residues at amino terminal ends. Some observed topological incongruences in maximum likelihood trees of complete and curated Tollip data sets could be explained through horizontal transfers, evidenced by recombination detection. These results suggest that there is more to be researched and understood about this protein.

Introduction: The effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated. Methods: A. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined. Results: At concentrations of 0.25, 0.5, 1, and 2%, PBO showed a signifi cant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only. Conclusions: The results of the biochemical assays suggest that PBO has a signifi cant inhibitory effect on the total esterase activity in A. aegypti larvae.Keywords: Temephos. Insecticide resistance. Aedes aegypti. Esterases.Dengue fever, a major viral disease, is a serious public health problem, especially in tropical countries where the climate and urban culture provide optimal conditions for the development and proliferation of its main vector, the mosquito Aedes aegypti 1 . The control of A. aegypti is primarily based on the use of chemical and biological products that are integrated with environmental management programs. Public programs aimed at controlling mosquitoes are characterized by the use of commercial insecticides, including organophosphates and pyrethroids. The organophosphate temephos (TE) was widely used in Brazil to control A. aegypti larvae until recently; however, due to reports of vector resistance to this insecticide, this method was replaced by the National Dengue Control Program. Nevertheless, TE remains on the list of insecticides to control dengue in Brazil and may be used again in the future 2,3 .The resistance to insecticides has contributed to an increase in A. aegypti populations and the incidence of dengue cases in Asia, and Central and South America, especially in Brazil 2,4 .The biochemical mechanisms involved in the development of resistance to insecticides include detoxifi cation metabolism processes. Several enzymes and enzyme systems participate in these processes, including oxidases, esterases, and transferases 5 . These enzymes allow the insect to convert an insecticide to a nontoxic form or to rapidly eliminate the compound from the body.Synergists such as piperonyl butoxide (PBO) have been employed in an attempt to overcome resistance to insecticides. Synergists are known to act as an alternative substrate, competing with the insecticide and interfering with detoxification. Synergists also act allosterically to inhibit the binding sites of esterases and multifunction oxidases (MFOs), minimizing the amount of insecticide needed to control insects and the levels of environmental contamination by pesticide residues 6 .Several studies have demonstrate...

No abstract

Agradeço primeiramente aos meus pais, João de Deus e Clarice, e ao meu irmão Lelis sem os quais eu não conseguiria chegar onde cheguei.Ao Prof. Dr. Malcon Antônio Manfredi Brandeburgo que foi meu orientador na monografia e no doutorado e abriu as portas do laboratório me dando a oportunidade de trilhar esse caminho.Ao Prof. Dr. Warwick Estevam Kerr que foi meu orientador na iniciação científica.Ao Prof. Dr. Carlos Ueira Vieira, que me orientou no mestrado e me inseriu na área da genética ligada ao sistema imune. À Prof. Dra. Ana Maria Bonetti, que orientou a mim e aos meus amigos de laboratório durante todos nossos trabalhos, sendo uma segunda mãe para todos nós.Agradeço aos meus amigos de laboratório (LABGEN), professores e alunos dos outros laboratórios, (Nanobiotecnologia) e (Labitox). Em especial à Juliana