Role of bioactive compounds in the gastrointestinal host-pathogen interaction of poultry and swine

The better understanding of mechanisms at the basis of host-pathogen interaction can represent a valid tool to increase productivity and contain economic losses in animal production through the maintenance of intestinal homeostasis. With this project, three preliminary in vitro studies were conducted with the aim of investigating how bioactive compounds could influence mechanisms of host-pathogen interaction in poultry and swine. Different panels of nature identical compounds, medium chain fatty acids, and plant extracts were employed against strains of Salmonella Typhimurium, Brachyspira hyodysenteriae, and Salmonella Enteritidis, respectively. When bacterial field strains were tested, the comparison between natural compounds and antibiotics was examined, with the aim of evaluating the role of the substances in the antibiotic-resistance context. Results demonstrate that bioactive compounds have positive effects on the host, the pathogen, or both in different experimental conditions. Additionally, when compared to antibiotics, bioactive compounds have proven to be valid alternatives to address the phenomenon of antibiotic resistance.

Exploring the internal kinematics of Galactic Globular Cluster cores

Globular clusters (GCs) are traditionally described as simple quasi-relaxed non-rotating stellar systems, characterized by spherical symmetry and isotropy in velocity space. However, recent studies have shown deviations from isotropic velocity distributions and significant internal rotation in many GCs, suggesting that their internal structure and kinematics are more complex than previously thought. The aim of this thesis is to investigate the internal kinematics of Galactic Globular Clusters (GGCs) as part of the Multi-Instrument Kinematic Survey (MIKiS), which exploits the capabilities of different ESO-VLT spectrographs to obtain comprehensive velocity dispersion (VD) and rotation profiles of GGCs. Moreover, this thesis has the particular goal of unraveling the kinematics of GC cores, which are still largely unexplored, by taking advantage of the exceptional spatial resolution of the adaptive-optics assisted integral-field spectrograph MUSE/NFM. The thesis presents a thorough kinematic study of three GGCs NGC 1904, NGC 6440, and NGC 6569. By combining the data sets acquired with four different spectrographs, we obtained the radial velocity (RV) of more than 1000 individual stars in each cluster, sampling from the innermost to the outermost regions. This allowed us to obtain the entire VD profile of each cluster and exclude the presence of an intermediate-mass black hole in the core of NGC 1904, at odds with previous findings obtained from integrated-light spectra. The studies also revealed signatures of internal rotation in each of the GCs studied. These results, supported by those of N-body simulations, prove that GCs were born with a significant initial rotation that they gradually lost through internal two-body relaxation and angular momentum loss carried away by escaping stars. Furthermore, we derived the structural parameters of NGC 6440 and NGC 6569, obtaining a comprehensive overview of the internal kinematics and structure of these GCs, which is necessary to properly reconstruct the evolutionary history of these systems.