The contest of microbial pigeon neighbors: Interspecies competition between Serratia marcescens and the human pathogen Cryptococcus neoformans.

In nature, microorganisms often exhibit competitive behavior for nutrients and limited space, allowing them to alter the virulence determinants of pathogens. The human pathogenic yeast Cryptococcus neoformans can be found organized in biofilms, a complex community composed of an extracellular matrix which confers protection against predation. The aim of this study was to evaluate and characterize antagonistic interactions between two cohabiting microorganisms: C. neoformans and the bacteria Serratia marcescens. The interaction of S. marcescens with C. neoformans expressed a negative effect on biofilm formation, polysaccharide capsule, production of urease, and melanization of the yeast. These findings evidence that competition in mixed communities can result in dominance by one species, with direct impact on the physiological modulation of virulence determinants. Such an approach is key for understating the response of communities to the presence of competitors and, ultimately, rationally designing communities to prevent and treat certain diseases.

Sobre a relação humano-cão / Concerning the human-dog relationship / La relation homme-chien / Sobre la relación humano-perro

Resumo Neste artigo são discutidos aspectos concernentes ao início do convívio entre cães e humanos e às diferenças culturais que afetam as relações entre as duas espécies. O estudo das interações entre humanos e cães precisa trazer à tona a pluralidade de fenômenos interconectados: o processo de domesticação iniciado há milhares de anos, os efeitos evolutivos da relação entre as duas espécies e os aspectos culturais que influenciam a convivência entre nós. Considerando essa visão holística, enxergamos de maneira ampla o cenário interacionista, estabelecendo paralelos muitas vezes ignorados por estudos pontuais e/ou enviesados por paradigmas experimentais de baixa relevância ecológica para os animais.

Abstract This article discusses the beginning of the relationship between dogs and humans and the cultural differences that affect the relationships between the two species. The study of interactions between humans and dogs needs to bring to light its plurality of interconnected phenomena: the domestication process that began thousands of years ago, the evolutionary effects of their relationship and the cultural aspects that influence such coexistence. Given this holistic view, we perceive this interaction scenario broadly, establishing parallels often ignored by one-off studies and/or biased by experimental paradigms of low ecological relevance to animals.

Résumé Dans cet article sont discutés des aspects liés au début de la cohabitation entre les chiens et les humains et les différences culturelles qui affectent ces relations interspécifiques. L'étude des interactions entre humains et chiens doit faire apparaître la pluralité des phénomènes reliés entre eux : le processus de domestication qui a commencé il y a milliers d'années, les effets évolutifs de cette relation et les aspects culturels qui influencent la coexistence entre nous. Compte tenu de cette vision holistique, c'est possible de voir largement le scénario interactionniste, et d'établir des parallèles souvent ignorés par les études individuelles ou biaisé par des paradigmes expérimentaux d'importance écologique négligeable pour les animaux.

Resumen Este artículo analiza los aspectos relacionados con el comienzo de la relación entre perros y humanos, y las diferencias culturales que afectan las relaciones entre las dos especies. El estudio de las interacciones entre humanos y perros necesita sacar a la luz la pluralidad de fenómenos interconectados: el proceso de domesticación que comenzó hace miles de años, los efectos evolutivos de la relación entre las dos especies y los aspectos culturales que influyen en la convivencia entre nosotros. Teniendo en cuenta esta visión holística, vemos el panorama interaccionista de manera general, estableciendo paralelos a menudo ignorados por estudios específicos y/o sesgados por paradigmas experimentales de baja relevancia ecológica para los animales.