Changes in Bacterial Gut Composition in Parkinson's Disease and Their Metabolic Contribution to Disease Development: A Gut Community Reconstruction Approach.

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disease with the major symptoms comprising loss of movement coordination (motor dysfunction) and non-motor dysfunction, including gastrointestinal symptoms. Alterations in the gut microbiota composition have been reported in PD patients vs. controls. However, it is still unclear how these compositional changes contribute to disease etiology and progression. Furthermore, most of the available studies have focused on European, Asian, and North American cohorts, but the microbiomes of PD patients in Latin America have not been characterized. To address this problem, we obtained fecal samples from Colombian participants (n = 25 controls, n = 25 PD idiopathic cases) to characterize the taxonomical community changes during disease via 16S rRNA gene sequencing. An analysis of differential composition, diversity, and personalized computational modeling was carried out, given the fecal bacterial composition and diet of each participant. We found three metabolites that differed in dietary habits between PD patients and controls: carbohydrates, trans fatty acids, and potassium. We identified six genera that changed significantly in their relative abundance between PD patients and controls, belonging to the families Lachnospiraceae, Lactobacillaceae, Verrucomicrobioaceae, Peptostreptococcaceae, and Streptococcaceae. Furthermore, personalized metabolic modeling of the gut microbiome revealed changes in the predicted production of seven metabolites (Indole, tryptophan, fructose, phenylacetic acid, myristic acid, 3-Methyl-2-oxovaleric acid, and N-Acetylneuraminic acid). These metabolites are associated with the metabolism of aromatic amino acids and their consumption in the diet. Therefore, this research suggests that each individual's diet and intestinal composition could affect host metabolism. Furthermore, these findings open the door to the study of microbiome-host interactions and allow us to contribute to personalized medicine.

Social context modulates scale-free movements in a social insect.

Most animals move intermittently, pausing or slowing down for short moments and short moves, and darting away towards a new location where to hover again. This pattern occurs at a range of spatial and temporal scales (thence, resembling 'scale-free'), from the quick inspection of local areas to the sum of all movements performed from birth to death. While this pattern has been extensively described, its proximate drivers remain open to debate. A current hypothesis states that underlying proximate generative mechanisms of intermittent movement of animals are linked to external stimuli, e.g., interactions with the abiotic environment, resources, and other individuals. Here we investigated a prediction from this hypothesis, using termites as a biological model. We verified whether the social background in which a termite is inserted will modify the parameters of its intermittent scale-free spatial displacement. This relates to the hypothesis because it inspects how do external stimuli coming from intraspecifics can affect this type of movement. We tracked the trajectories of a focal termite confined along its nestmates in experimental clueless arenas, every 0.5 s along about six hours. Arenas varied in group size and comprised 22 distinct caste compositions, yielding 75 trackings (> 400 h) and more than two million Cartesian coordinates. Most of these trajectories (96% or 72/75) were classified as intermittent scale free (Lévy-like), indicating prevalence of this type of movement over non-Lévy-like ones (P=1.62×10-15). Moreover, intermittent scale-free movements performed by the focal termite (i) did arise outside the foraging-searching framework, and (ii) were modified by the social context while remaining within the limits of Lévy-walk realms. That is, some limits seem to exist along with the necessary plasticity to provide room for natural selection. Moreover, by arising outside the foraging framework, Lévy-like movements are shown to have broader relevance. Studies on processes that depend on social context and movement (e.g., collective behaviour, the spread of diseases) may, hence, profit from such concepts.