Free amino acid and acylcarnitine values in Ursus americanus Pallas 1780 (black bear) from Northeastern Mexico.

INTRODUCTION: Ursus americanus Pallas 1780 is the largest carnivore and the only ursid in Mexico. It is considered an endangered species in the country because its distribution and population have been reduced by up to 80% because of habitat loss or furtive hunting. These problems can lead to a diet change, which could result in metabolic disorders, such as fatty acid ß-oxidation defects or organic acid metabolism disorders. In our study, a free amino acid and acylcarnitine profile was characterized. METHODS: Peripheral blood samples were drawn from nine free-ranging black bears in a period of five months, from June to October of 2019 in Northeastern Mexico, and 12 amino acids and 30 acylcarnitines were determined and quantified. Age differences were observed in the samples through ANOVA and post-hoc Tukey test. RESULTS: Only three metabolites showed a significant difference with age: alanine (Ala) [cubs vs juvenile], free-carnitine (C0) [juvenile vs cubs] and acetylcarnitine (C2) [cubs vs adults and juvenile vs cubs]. CONCLUSION: Metabolites with variability due to age were identified, making them potential biomarkers to monitor metabolic status as early diagnosis in endangered species. This is the first study of black bear amino acid and acylcarnitine profiles, and the values found could be used as reference for free amino acid and acylcarnitine concentrations in further studies of the species.

Suppression of Midgut Microbiota Impact Pyrethroid Susceptibility in Aedes aegypti.

Aedes aegypti is a mosquito that transmits viral diseases such as dengue, chikungunya, Zika, and yellow fever. The insect's microbiota is recognized for regulating several biological processes, including digestion, metabolism, egg production, development, and immune response. However, the role of the bacteria involved in insecticide susceptibility has not been established. Therefore, the objective of this study was to characterize the resident microbiota in a field population of A. aegypti to evaluate its role associated with susceptibility to the insecticides permethrin and deltamethrin. Mosquitoes were fed 10% sucrose mixed with antibiotics and then exposed to insecticides using a diagnostic dose. DNA was extracted, and sequencing of bacterial 16S rRNA was carried out on Illumina® MiSeq™. Proteobacteria (92.4%) and Bacteroidetes (7.6%) were the phyla, which are most abundant in mosquitoes fed with sucrose 10%. After exposure to permethrin, the most abundant bacterial species were Pantoea agglomerans (38.4%) and Pseudomonas azotoformans-fluorescens-synxantha (14.2%). Elizabethkingia meningoseptica (38.4%) and Ps. azotoformans-fluorescens-synxantha (26.1%) were the most abundant after exposure to deltamethrin. Our results showed a decrease in mosquitoes' survival when exposed to permethrin, while no difference in survival when exposed to deltamethrin when the microbiota was modified. We found that the change in microbiota modifies the response of mosquitoes to permethrin. These results are essential for a better understanding of mosquito physiology in response to insecticides.

miRNAs of Aedes aegypti (Linnaeus 1762) conserved in six orders of the class Insecta.

Aedes aegypti L. is the most important vector of arboviruses such as dengue, Zika, chikungunya, Mayaro, and yellow fever, which impact millions of people's health per year. MicroRNA profile has been described in some mosquito species as being important for biological processes such as digestion of blood, oviposition, sexual differentiation, insecticide resistance, and pathogens dissemination. We identified the miRNAs of Ae. aegypti females, males and eggs of a reference insecticide susceptible strain New Orleans and compared them with those other insects to determine miRNA fingerprint by new-generation sequencing. The sequences were analyzed using data mining tools and categorization, followed by differential expression analysis and conservation with other insects. A total of 55 conserved miRNAs were identified, of which 34 were of holometabolous insects and 21 shared with hemimetabolous insects. Of these miRNAs, 32 had differential expression within the stages analyzed. Three predominant functions of miRNA were related to embryonic development regulation, metamorphosis, and basal functions. The findings of this research describe new information on Ae. aegypti physiology which could be useful for the development of new control strategies, particularly in mosquito development and metamorphosis processes.

Frequency and intensity of pyrethroid resistance through the CDC bottle bioassay and their association with the frequency of kdr mutations in Aedes aegypti (Diptera: Culicidae) from Mexico.

BACKGROUND: The control of Aedes aegypti (L.), the main urban vector that causes arboviral diseases such as dengue, Chikungunya and Zika, has proved to be a challenge because of a rapid increase in insecticide resistance. Therefore, adequate monitoring of insecticide resistance is an essential element in the control of Ae. aegypti and the diseases it transmits. We estimated the frequency and intensity (Resistance Frequency Rapid Diagnostic Test [F-RDT] and Resistance Intensity Rapid Diagnostic Test [I-RDT]) of pyrethroid resistance in populations of Ae. aegypti from Mexico using the bottle bioassay and results were related to the frequencies of knockdown resistance (kdr) mutations V1016I and F1534C. RESULTS: All populations under study were resistant to the pyrethroids: bifenthrin (99%), d-(cis-trans)-phenothrin (6.3% cis, 91.7% trans) and permethrin (99.5%) according to F-RDT, and showed moderate to high-intensity resistance at 10× the diagnostic dose (DD) in I-RDT. Frequencies of the kdr mutation V1016I in Ae. aegypti populations were correlated with moderate permethrin resistance at 10× DD, whereas F1534C mutation frequencies were correlated with high bifenthrin resistance at 5× DD. Both I1016 and C1535 were highly correlated with high-intensity phenothrin resistance at 1× to 10× DD. CONCLUSIONS: This study showed that high frequencies of kdr mutations V1016I and F1534C are reflected in the results of F-RDT and I-RDT tests. Bioassays in conjunction with the characterization of genetic resistance mechanisms are indispensable in the strategic and rational management of resistance in mosquitoes. © 2018 Society of Chemical Industry.

Profiles of Amino Acids and Acylcarnitines Related with Insecticide Exposure in Culex quinquefasciatus (Say).

Culex quinquefasciatus Say is a vector of many pathogens of humans, and both domestic and wild animals. Personal protection, reduction of larval habitats, and chemical control are the best ways to reduce mosquito bites and, therefore, the transmission of mosquito-borne pathogens. Currently, to reduce the risk of transmission, the pyrethroids, and other insecticide groups have been extensively used to control both larvae and adult mosquitoes. In this context, amino acids and acylcarnitines have never been associated with insecticide exposure and or insecticide resistance. It has been suggested that changes in acylcarnitines and amino acids profiles could be a powerful diagnostic tool for metabolic alterations. Monitoring these changes could help to better understand the mechanisms involved in insecticide resistance, complementing the strategies for managing this phenomenon in the integrated resistance management. The purpose of the study was to determine the amino acids and acylcarnitines profiles in larvae of Cx. quinquefasciatus after the exposure to different insecticides. Bioassays were performed on Cx. quinquefasciatus larvae exposed to the diagnostic doses (DD) of the insecticides chlorpyrifos (0.001 µg/mL), temephos (0.002 µg/mL) and permethrin (0.01 µg/mL). In each sample, we analyzed the profile of 12 amino acids and 31 acylcarnitines by LC-MS/MS. A t-test was used to determine statistically significant differences between groups and corrections of q-values. Results indicates three changes, the amino acids arginine (ARG), free carnitine (C0) and acetyl-carnitine (C2) that could be involved in energy production and insecticide detoxification. We confirmed that concentrations of amino acids and acylcarnitines in Cx. quinquefasciatus vary with respect to different insecticides. The information generated contributes to understand the possible mechanisms and metabolic changes occurring during insecticide exposure.