RESUMO
Animals use sound for communication, with high-amplitude signals being selected for attracting mates or deterring rivals. High amplitudes are attained by employing primary resonators in sound-producing structures to amplify the signal (e.g. avian syrinx). Some species actively exploit acoustic properties of natural structures to enhance signal transmission by using these as secondary resonators (e.g. tree-hole frogs). Male bush-crickets produce sound by tegminal stridulation and often use specialised wing areas as primary resonators. Interestingly, Acanthacara acuta, a Neotropical bush-cricket, exhibits an unusual pronotal inflation, forming a chamber covering the wings. It has been suggested that such pronotal chambers enhance amplitude and tuning of the signal by constituting a (secondary) Helmholtz resonator. If true, the intact system - when stimulated sympathetically with broadband sound - should show clear resonance around the song carrier frequency which should be largely independent of pronotum material, and change when the system is destroyed. Using laser Doppler vibrometry on living and preserved specimens, microcomputed tomography, 3D-printed models and finite element modelling, we show that the pronotal chamber not only functions as a Helmholtz resonator owing to its intact morphology but also resonates at frequencies of the calling song on itself, making song production a three-resonator system.
Assuntos
Comunicação Animal , Ortópteros/anatomia & histologia , Ortópteros/fisiologia , Asas de Animais/anatomia & histologia , Animais , Equador , Análise de Elementos Finitos , Masculino , Impressão Tridimensional , Vibração , Asas de Animais/fisiologia , Microtomografia por Raio-XRESUMO
Cholera was absent from the island of Hispaniola at least a century before an outbreak that began in Haiti in the fall of 2010. Pulsed-field gel electrophoresis (PFGE) analysis of clinical isolates from the Haiti outbreak and recent global travelers returning to the United States showed indistinguishable PFGE fingerprints. To better explore the genetic ancestry of the Haiti outbreak strain, we acquired 23 whole-genome Vibrio cholerae sequences: 9 isolates obtained in Haiti or the Dominican Republic, 12 PFGE pattern-matched isolates linked to Asia or Africa, and 2 nonmatched outliers from the Western Hemisphere. Phylogenies for whole-genome sequences and core genome single-nucleotide polymorphisms showed that the Haiti outbreak strain is genetically related to strains originating in India and Cameroon. However, because no identical genetic match was found among sequenced contemporary isolates, a definitive genetic origin for the outbreak in Haiti remains speculative.
Assuntos
Genoma Bacteriano , Vibrio cholerae/genética , África/epidemiologia , Alelos , Ásia/epidemiologia , Proteínas de Bactérias/genética , Cólera/epidemiologia , Toxina da Cólera/genética , Surtos de Doenças , Eletroforese em Gel de Campo Pulsado , Ordem dos Genes , Haiti/epidemiologia , Humanos , Sequências Repetitivas Dispersas/genética , Filogenia , Prófagos , Homologia de Sequência de Aminoácidos , Vibrio cholerae/classificação , Vibrio cholerae/isolamento & purificaçãoRESUMO
To increase understanding of drug-resistant Vibrio cholerae, we studied selected molecular mechanisms of antimicrobial drug resistance in the 2010 Haiti V. cholerae outbreak strain. Most resistance resulted from acquired genes located on an integrating conjugative element showing high homology to an integrating conjugative element identified in a V. cholerae isolate from India.