Affective contingencies in the affiliative domain: Physiological assessment, associations with the affiliation motive, and prediction of behavior

According to classical motive disposition theory, individuals differ in their propensity to derive pleasure from affiliative experiences. This propensity is considered a core process underlying the affiliation motive and a pervasive cause of motivated behavior. In this study, we tested these assumptions. We presented participants with positive affiliative stimuli and used electromyography to record changes in facial muscular activity that are indicative of subtle smiling. We were thus able to physiologically measure positive affect following affiliative cues. Individual differences in these affective contingencies were internally consistent and temporally stable. They converged with affiliation motive self- and informant reports and picture story exercise scores, indicating that they are partly accessible to the self, observable to outsiders, and overlap with implicit systems. Finally, they predicted affiliative behavior in terms of situation selection and modification across a wide variety of contexts (i.e., in daily life, the laboratory, and an online social network). These findings corroborate the long-held assumption that affective contingencies represent a motivational core aspect of affiliation

Isolation, in vitro characterization and efficacy assessment in Galleria mellonella larvae of four bacteriophages targeting Aeromonas salmonicida

The Gram-negative bacteria Aeromonas (A.) salmonicida is a primary fish pathogen that causes furunculosis in salmonids, carp and perch, as well as septicemia in a variety of fish. This species is considered as one of the main bacterial pathogens responsible for important economic losses in aquaculture industry. Large amounts of antibiotics are used to treat this infection, which highly contributes to the emergence of antibiotic-resistant strains. The application of bacteriophages (phages) in aquaculture seems to be a promising solution to control pathogenic bacteria in this field. The aims of this work were to isolate new phages active against A. salmonicida, characterize them in vitro and assess their potential use for phage therapy in a preliminary in vivo model. Four new phages were isolated from water samples collected in fish farms and natural aquatic environments in southern Belgium. Transmission electron microscopy allowed to classify these four phages in the Caudoviricetes class which includes tailed-phages with dsDNA and an icosahedral capsid. Genomic analysis showed that three of these phages, named vB_AsaM_ULASA2 (170,823bp), vB_AsaM_ULASA3 (164,381bp) and vB_AsaM_ULASA4 (171,205bp), belong to the Straboviridae family while vB_AsaM_ULASA1 (47,813bp) stay in the unclassified part of the Caudoviricetes class. Four strains of A. salmonicida were tested for virulence on Galleria mellonella larvae and two of them, named ATCC7965 and Asa-CER1, were selected for further experiments. Inoculation doses were determined as 102 CFU/10 µl and 104 CFU/10 µl, respectively. The safety and efficacy of the four phages at MOI 10 and 100 in this model are currently assessed

In vitro characterization and preliminary efficacy assessment in galleria mellonella larvae of four newly isolated bacteriophages targeting aeromonas salmonicida

The Gram-negative bacteria Aeromonas (A.) salmonicida is a primary fish pathogen that causes furunculosis in salmonids as well as septicemia in a variety of fish. In one hand because this disease is responsible for significant losses in salmonid production worldwide and in the other hand because of the frightening tendency of this bacteria to exhibit antimicrobial (multi-)resistances, phage therapy could represent a leading alternative to treat this infection in aquaculture. The aims of this study were to create a collection of A. salmonicida strains, isolate phages targeting these strains, phenotypically and genomically characterize these newly isolated phages and finally assess their potential for phage therapy in the preliminary in vivo model of Galleria (G.) mellonella larvae. Four new phages active against A. salmonicida were isolated from water samples collected in fish farms and natural aquatic environments in southern Belgium. Genomic analysis showed that 3 of these phages, named vB_AsaM_ULASA2 (170,823bp), vB_AsaM_ULASA3 (164,381bp) and vB_AsaM_ULASA4 (171,205bp), belong to the Straboviridae family while vB_AsaM_ULASA1 (47,813bp) stay in the unclassified part of the Caudoviricetes class. All 4 presented a myovirus morphotype. Four-day efficacy experiments in the preliminary in vivo model of G. mellonella larvae showed that 3 of these 4 phages were responsible for a significant extension in the larval survival time at the 2 treatment doses tested (MOI 10 and 100). In light of these results, these phages targeting A. salmonicida could represent potential new candidates for the development of anti-furunculosis phage treatments in aquacultur