Barreto, S. | Search bioRxiv

bioRxiv2022

Male-dominated courtship in an unexpectedly late-breeding Andean Lapwing (Vanellus resplendens) population

Sexual behavior, namely courtship and mating strategies, remain unexplored for numerous tropical birds. Andean Lapwing (Vanellus resplendens) is a shorebird inhabiting High Andes, and its reproductive biology is poorly known. Here, we performed standardized 49 observations of 20 pairs of Andean Lapwings at Laguna de Salinas, Peru (4315 m a.s.l.) during 2021-2022 breeding season. Lapwings in this studied population show social monogamy, a defined breeding season apparently triggered by rainfall, starting later than what is known according to the literature, and male-biased investment in courtship and territorial defense. These observations increase our knowledge on this understudied Neotropical species breeding at high elevations. RESUMENEl comportamiento sexual, es decir, las estrategias de cortejo y apareamiento, permanecen sin explorarse para numerosas aves tropicales. El Avefria Andina (Vanellus resplendens) es un ave playera que habita los altos Andes, sin embargo, su biologia reproductiva es poco conocida. Aqui, realizamos 49 observaciones estandarizadas de 20 parejas de avefrias andinas en Laguna de Salinas, Peru (4315 m.s.n.m.) durante la temporada 2021-2022. Las avefrias en esta poblacion estudiada muestran monogamia social, una temporada reproductiva bien definida provocada por las precipitaciones, comenzando mas tarde de lo que es descrito en la literatura, y una inversion predispuesta de machos en el cortejo y la defensa territorial. Estas observaciones aumentan nuestro conocimiento sobre esta especie Neotropical poco estudiada que se reproduce a gran altitud.

animal behavior and cognition↗

bioRxiv2021

Interbacterial transfer of carbapenem resistance and large antibiotic resistance islands by natural transformation in pathogenic Acinetobacter

Acinetobacter baumannii infection poses a major health threat with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intra-, but also inter-strain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4, AbaR1) than when the same bacteria are supplied with large amounts of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genome of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombinants and results from both spontaneous release and interbacterial predatory behavior. In the light of our results, natural transformation should be considered as a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii. ImportanceAcinetobacter baumannii is a multidrug resistant pathogen responsible for difficult-to-treat hospital-acquired infections. Understanding the mechanisms leading to the emergence of the multi-drug resistance in this pathogen is today crucial. Horizontal gene transfer is assumed to largely contribute to this multidrug resistance. However, in A. baumannii, the mechanisms leading to genome recombination and the horizontal transfer of resistance genes are poorly understood. We bring experimental evidence that natural transformation, a horizontal gene transfer mechanism recently highlighted in A. baumannii, allows the highly efficient interbacterial transfer of genetic elements carrying resistance to last line antibiotic carbapenems. Importantly, we demonstrated that natural transformation, occurring in mixed populations of Acinetobacter, enables the transfer of large resistance island mobilizing multiple resistance genes.

microbiology↗