Biology subjects

Meda, N.

Publications and source records attributed to Meda, N..

5 recordsLinked to original sources

bioRxiv2021

The Core Human Fecal Metabolome

Summary ParagraphAmong the biomolecules at the center of human health and molecular biology is a system of molecules that defines the human phenotype known as the metabolome. Through an untargeted metabolomic analysis of fecal samples from human individuals from Africa and the Americas--the birthplace and the last continental expansion of our species, respectively--we present the characterization of the core human fecal metabolome. The majority of detected metabolite features were ubiquitous across populations, despite any geographic, dietary, or behavioral differences. Such shared metabolite features included hyocholic acid and cholesterol. However, any characterization of the core human fecal metabolome is insufficient without exploring the influence of industrialization. Here, we show chemical differences along an industrialization gradient, where the degree of industrialization correlates with metabolomic changes. We identified differential metabolite features like leucyl-leucine dipeptides and urobilin as major metabolic correlates of these behavioral shifts. Our results indicate that industrialization significantly influences the human fecal metabolome, but diverse human lifestyles and behavior still maintain a core human fecal metabolome. This study represents the first characterization of the core human fecal metabolome through untargeted analyses of populations along an industrialization gradient.

biochemistry↗

bioRxiv2020

Hierarchical Spatial Search Strategies in Drosophila

Humans rely on multiple systems of sensory information to make decisions. However, strategies that shorten decision-making time by taking into account fewer but more essential elements of information are preferred to strategies involving complex analyses. These "shortcuts to decision" are also termed "heuristics". The identification of heuristic principles in species phylogenetically distant to humans would shed light on the evolutionary origin of speed-accuracy trade-offs and offer the possibility to investigate the brain representations of such trade-offs, urgency, and uncertainty. During experiments on spatial learning, we acknowledged that the search strategies of the invertebrate Drosophila melanogaster, the common fruit fly, resembled a spatial heuristic. Here we show that the fruit fly applies a heuristic termed the "Nearest Neighbour Rule" to avoid bitter taste (a negative stimulation). That is, the fly visits the salient location closest to its current position to hopefully stop the negative stimulation. Only if this strategy proves unsuccessful, the animal uses other learned associations to avoid bitter taste. The acknowledgement of a heuristic in D. melanogaster supports the view that invertebrates can leverage on economic principles when making choices and that the existence of heuristics in evolution dates to at least 600 million years ago.

neuroscience↗

bioRxiv2019

CoproID predicts the source of coprolites and paleofeces using microbiome composition and host DNA content

Shotgun metagenomics applied to archaeological feces (paleofeces) can bring new insights into the composition and functions of human and animal gut microbiota from the past. However, paleofeces often undergo physical distortions in archaeological sediments, making their source species difficult to identify on the basis of fecal morphology or microscopic features alone. Here we present a reproducible and scalable pipeline using both host and microbial DNA to infer the host source of fecal material. We apply this pipeline to newly sequenced archaeological specimens and show that we are able to distinguish morphologically similar human and canine paleofeces, as well as non-fecal sediments, from a range of archaeological contexts.

microbiology↗

bioRxiv2019

Searching for relief: Drosophila melanogaster navigation in a virtual bitter maze

Animals use pain-relief learning to discern which actions can diminish or abolish noxious stimuli. If relief from pain is provided in a specific location, place learning is the mechanism used to pinpoint that location in space. Little is known about how physiological and non-directly damaging stimuli can alter visual-based searching behaviour in animals. Here we show how the optogenetically-induced activation of bitter-sensing neurons urges Drosophila melanogaster to seek relief from bitter taste stimulation and that this distressful, but ecologically relevant stimulus, innately wired to the threat of intoxication, is sufficient to elicit pain-relief-like behavioural responses. Specifically, freely walking flies inside an open circular arena are trained to seek relief from the unpleasant stimulation by searching for a safe area alternatively positioned in the proximity of a pair of identical, diametrically opposed, visual markers. Moreover, and perhaps more importantly, under this paradigm flies develop visual place learning manifested by their seeking relief in the zone associated with bitter relief during the last trial of training, even when exposed to constant bitter stimulation with no relief provided. An important implication is that this form of learning does not lead to operant conditioning generalization. We further propose that kinematic indexes, such as the spatially-specific reduction of locomotor velocity, may provide immediate evidence of relief-based place learning and spatial memory.

animal behavior and cognition↗

bioRxiv2019

Factors associated with adherence to the Integrated Management of Childhood Illness (IMCI) guidelines for under-five years’ old care in Burkina Faso primary health care facilities

ObjectiveTo assess the adherence to Integrated Management of Childhood Illness (IMCI) guidelines in primary health care facilities in Burkina Faso and to determine the factors associated.\n\nMaterials and MethodsWe used data from a large survey on health facilities, held from October 2013 to April 2014. Primary health facilities were evaluated, health workers interviewed and consultations observed. The standard guideline for an under five years old child consultation was the Integrated Management of Childhood Illness (IMCI).\n\nResults1,571 consultations were observed, carried out by 522 different practitioners. The danger signs were usually not checked (13.9% only checking for at least three general danger signs). The adherence for cough (74.8%), diarrhoea (64.9%), fever (83.8%) and anaemia (70.3%) was higher. The principal factors found to be associated with poorer adherence to guidelines of consultation were female sex (Rate Ratio (RR) = 0.91; 95% CI 0.86 - 0.95), non-nurse practitioner (RR=0.93; 95% CI 0.88 - 0.97), IMCI training (RR=1.06; 95% CI 1.01 - 1.11), non-satisfaction of the salary (RR=0.95 95% CI 0.91 - 0.99).\n\nConclusionThis study highlights a poor adherence to the IMCI guidelines and by then, revealing a poor quality of under-five care. Indeed, many characteristics of health workers including gender, type of profession, training satisfaction with salary were found to be associated with this adherence. Therefore, more initiatives aiming at improving the quality of care should be developed and implemented for improving the child health care.

epidemiology↗