212 research outputs found
Fishy forensics: FT-NIR and machine learning based authentication of Mediterranean anchovies (Engraulis encrasicolus)
No full textSeafood authentication and traceability is a challenging issue owing to its complex supply chain and fishing in international waters. NIR spectroscopy has been successfully used to authenticate food of animal and plant origin. In this study, FT-NIR was used to discriminate between Mediterranean anchovies (Engraulis encrasicolus) fished from Adriatic, Balearic, and Tyrrhenian Sea. The spectra were prepared using the standard normal variate (SNV) and the Savitzky-Golay 1st derivative, 2nd order (SG), as well as both together. The model was built, after outlier removal, with linear-support vector machine (L-SVM), polynomial-SVM (P-SVM), k-nearest neighbor (k-NN) and Random Forest (RF). Spectral preprocessing improved model classification accuracy for all algorithms. The data could not be put into groups by linear algorithms like L-SVM and k-NN because the NIR spectra were not linear and had many columns. Non-linear algorithms, P-SVM and RF when coupled with SG+SNV, successfully produced models with maximum robustness. P-SVM and RF models had 100 % accuracy in training set and 95.7 % and 95.5 % accuracy in testing set, respectively and 95.2 and 95.1 accuracy in cross-validation set
Wild immunology: converging on the real world
No full textRecently, the Centre for Immunity, Infection and Evolution sponsored a one-day symposium entitled "Wild Immunology." The CIIE is a new Wellcome Trust-funded initiative with the remit to connect evolutionary biology and ecology with research in immunology and infectious diseases in order to gain an interdisciplinary perspective on challenges to global health. The central question of the symposium was, "Why should we try to understand infection and immunity in wild systems?" Specifically, how does the immune response operate in the wild and how do multiple coinfections and commensalism affect immune responses and host health in these wild systems? The symposium brought together a broad program of speakers, ranging from laboratory immunologists to infectious disease ecologists, working on wild birds, unmanaged animals, wild and laboratory rodents, and on questions ranging from the dynamics of coinfection to how commensal bacteria affect the development of the immune system. The meeting on wild immunology, organized by Amy Pedersen, Simon Babayan, and Rick Maizels, was held at the University of Edinburgh on 30 June 2011
Diverse host-seeking behaviors of skin-penetrating nematodes.
No full textSkin-penetrating parasitic nematodes infect approximately one billion people worldwide and are responsible for some of the most common neglected tropical diseases. The infective larvae of skin-penetrating nematodes are thought to search for hosts using sensory cues, yet their host-seeking behavior is poorly understood. We conducted an in-depth analysis of host seeking in the skin-penetrating human parasite Strongyloides stercoralis, and compared its behavior to that of other parasitic nematodes. We found that Str. stercoralis is highly mobile relative to other parasitic nematodes and uses a cruising strategy for finding hosts. Str. stercoralis shows robust attraction to a diverse array of human skin and sweat odorants, most of which are known mosquito attractants. Olfactory preferences of Str. stercoralis vary across life stages, suggesting a mechanism by which host seeking is limited to infective larvae. A comparison of odor-driven behavior in Str. stercoralis and six other nematode species revealed that parasite olfactory preferences reflect host specificity rather than phylogeny, suggesting an important role for olfaction in host selection. Our results may enable the development of new strategies for combating harmful nematode infections
Experience-dependent olfactory behaviors of the parasitic nematode Heligmosomoides polygyrus.
No full textParasitic nematodes of humans and livestock cause extensive disease and economic loss worldwide. Many parasitic nematodes infect hosts as third-stage larvae, called iL3s. iL3s vary in their infection route: some infect by skin penetration, others by passive ingestion. Skin-penetrating iL3s actively search for hosts using host-emitted olfactory cues, but the extent to which passively ingested iL3s respond to olfactory cues was largely unknown. Here, we examined the olfactory behaviors of the passively ingested murine gastrointestinal parasite Heligmosomoides polygyrus. H. polygyrus iL3s were thought to reside primarily on mouse feces, and infect when mice consume feces containing iL3s. However, iL3s can also adhere to mouse fur and infect orally during grooming. Here, we show that H. polygyrus iL3s are highly active and show robust attraction to host feces. Despite their attraction to feces, many iL3s migrate off feces to engage in environmental navigation. In addition, H. polygyrus iL3s are attracted to mammalian skin odorants, suggesting that they migrate toward hosts. The olfactory preferences of H. polygyrus are flexible: some odorants are repulsive for iL3s maintained on feces but attractive for iL3s maintained off feces. Experience-dependent modulation of olfactory behavior occurs over the course of days and is mediated by environmental carbon dioxide (CO2) levels. Similar experience-dependent olfactory plasticity occurs in the passively ingested ruminant-parasitic nematode Haemonchus contortus, a major veterinary parasite. Our results suggest that passively ingested iL3s migrate off their original fecal source and actively navigate toward hosts or new host fecal sources using olfactory cues. Olfactory plasticity may be a mechanism that enables iL3s to switch from dispersal behavior to host-seeking behavior. Together, our results demonstrate that passively ingested nematodes do not remain inactive waiting to be swallowed, but rather display complex sensory-driven behaviors to position themselves for host ingestion. Disrupting these behaviors may be a new avenue for preventing infections
AUTHORS’ RESPONSE
No full textAuthor\u27s response to the forum of ideas created through the responses by Manulani Aluli Meyer, Ty P. Kāwika Tengan, and Chad Kalepa Babayan
The impact of nutrition and helminth infection on gut health and the microbiome using a lab-to-wild mouse model
No full textThe mammalian gastrointestinal tract is a rich ecosystem composed of complex interactions. It is home to a diverse community of bacterial microbes known as the gut microbiota, the preferential niche for many helminth parasites and the largest site of both the immune system and diet-derived nutrient absorption. To date, most studies exploring the relationship between nutrition, helminth infection and immunity, and the gut microbiota have utilised controlled laboratory-rodent models, with intentionally limited genetic, ecological, and behavioural variation. While these controlled studies have been very valuable for understanding mechanisms, they are limited in their ability to extrapolate the outcome of these interactions to natural populations. Using a lab-to-wild mouse model, with both wild and laboratory-reared wood mice (Apodemus sylvaticus), the key aim of my thesis is to use this unique approach to both elucidate the impacts of nutrition and helminth infection on the gut microbiota and health in the lab, and then importantly to test the consequences of these interactions in the wild.
First, I characterised the gut microbiota of our recently derived paired laboratory wood mouse colonies, and found that our formerly wild, but laboratory-reared wood mice had a wild-like gut microbiota (Wild-like: A. sylvaticus), similar, although less diverse than wild wood mice. In contrast, our recently caesarean re-derived wood mouse colony, who were fostered by standard laboratory mice (Mus musculus) had a more lab-like gut microbiota (Lab-like: A. sylvaticus), but also shared many bacterial taxa with other Wild-like:As mice. Then, I investigated how these Wild-like:As and Lab-like:As colonies responded to infection with the gastrointestinal helminth, Heligmosomoides polygyrus, which is a natural parasite of wood mice within the wild. I assessed how the diversity and stability of the microbiota composition was altered over the course of infection and determined if this differed between the two colonies. I found that immune responses differed between the two wood mouse colonies and that this was impacted by helminth infection, whereby infection was associated with a decrease in gut-microbiota diversity of Wild-like:As mice, but not Lab-like:As mice.
Previously, we have shown that wood mice given a high-quality supplemented diet, were more resistant to helminth infection and generated stronger immune responses, in both the wild and our wild-like colony. Here, I expanded upon the findings of this earlier study, by investigating the role of the gut microbiota on the impact of high-quality diet supplementation and improving helminth resistance. I found that nutrition and to a lesser extent helminth infection significantly drive the microbiota composition and diversity in both lab and wild wood mice; and could be, in part, important in driving the impact of nutrition on helminth immunity.
Overall, this thesis both develops an exciting new lab-to-wild mouse model that will enable both mechanistic studies in the lab, and fitness-relevant experiments in the field to better understand the complex interactions between nutrition, infection, the gut microbiota, and health. Importantly, my results show that the gut microbiota is an important player in the gut ecosystem, and my results provide a greater understanding of how the interplay between nutrition, immunity and helminthiasis can impact host health and infection dynamics
Wild immunology: converging on the real world
No full textRecently, the Centre for Immunity, Infection and Evolution sponsored a one-day symposium entitled “Wild Immunology.” The CIIE is a new Wellcome Trust–funded initiative with the remit to connect evolutionary biology and ecology with research in immunology and infectious diseases in order to gain an interdisciplinary perspective on challenges to global health. The central question of the symposium was, “Why should we try to understand infection and immunity in wild systems?” Specifically, how does the immune response operate in the wild and how do multiple coinfections and commensalism affect immune responses and host health in these wild systems? The symposium brought together a broad program of speakers, ranging from laboratory immunologists to infectious disease ecologists, working on wild birds, unmanaged animals, wild and laboratory rodents, and on questions ranging from the dynamics of coinfection to how commensal bacteria affect the development of the immune system. The meeting on wild immunology, organized by Amy Pedersen, Simon Babayan, and Rick Maizels, was held at the University of Edinburgh on 30 June 2011
Phylogenomics and analysis of shared genes suggest a single transition to mutualism in Wolbachia of nematodes
No full textWolbachia, endosymbiotic bacteria of the order Rickettsiales, are widespread in arthropods but also present in nematodes. In arthropods, A and B supergroup Wolbachia are generally associated with distortion of host reproduction. In filarial nematodes, including some human parasites, multiple lines of experimental evidence indicate that C and D supergroup Wolbachia are essential for the survival of the host, and here the symbiotic relationship is considered mutualistic. The origin of this mutualistic endosymbiosis is of interest for both basic and applied reasons: How does a parasite become a mutualist? Could intervention in the mutualism aid in treatment of human disease? Correct rooting and high-quality resolution of Wolbachia relationships are required to resolve this question. However, because of the large genetic distance between Wolbachia and the nearest outgroups, and the limited number of genomes so far available for large-scale analyses, current phylogenies do not provide robust answers. We therefore sequenced the genome of the D supergroup Wolbachia endosymbiont of Litomosoides sigmodontis, revisited the selection of loci for phylogenomic analyses, and performed a phylogenomic analysis including available complete genomes (from isolates in supergroups A, B, C, and D). Using 90 orthologous genes with reliable phylogenetic signals, we obtained a robust phylogenetic reconstruction, including a highly supported root to the Wolbachia phylogeny between a (A + B) clade and a (C + D) clade. Although we currently lack data from several Wolbachia supergroups, notably F, our analysis supports a model wherein the putatively mutualist endosymbiotic relationship between Wolbachia and nematodes originated from a single transition event
Object distance estimation algorithm for real-time FPGA-based stereoscopic vision system
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