Influence of season and site location on European cultured sea bass parasites in Corsican fish farms using indicator species analysis (IndVal)

Rapamycin extenuates experimental colitis by modulating the gut microbiota

BACKGROUND AND AIM

Autophagy and gut microbiota correlates closely with the inflammatory bowel disease. Herein, we aimed to study the roles of rapamycin on the gut microbiota in inflammatory bowel disease.

METHODS

Acute colitis was induced with dextran sodium sulfate (DSS) and 2,4,6-trinitrobenzenesulfonic acid solution in mice. Mice were administered with rapamycin or hydroxychloroquine. Weight loss, disease activity index scores, histopathological score, serum inflammatory cytokines, intestinal permeability, and colonic autophagy-related proteins were detected. Cecal content was also preserved in liquid nitrogen and subsequently analyzed following the 16S DNA sequencing. The antibiotic cocktail-induced microbiome depletion was performed to further investigate the relationship between autophagy activation and gut microbiota.

RESULTS

Compared with the control group, the colonic autophagy-related proteins of P62, mTOR, and p-mTOR increased significantly, while the levels of LC3B and ATG16L1 decreased (all P < 0.05) in the model group. After rapamycin intervention, the colonic pathology of mice improved, while the disease activity index score decreased substantially; the colon length increased, and the expression of IL-6 and TNF-α decreased. Following hydroxychloroquine treatment, some indicators suggested aggravation of colitis. Principal coordinates analysis showed that the DSS group was located on a separate branch from the rapamycin group but was closer to the hydroxychloroquine group. Compared with the DSS group, the rapamycin group was associated with higher abundances of f_Lactobacillaceae (P = 0.0151), f_Deferribacteraceae (P = 0.0290), g_Lactobacillus (P = 0.0151), g_Mucispirillum (P = 0.0137), s_Lactobacillus_reuteri (P = 0.0028), and s_Clostridium_sp_Culture_Jar-13 (P = 0.0082) and a lower abundance of s_Bacteroides_sartorii (P = 0.0180). Linear discriminant analysis effect size showed that rapamycin increased the abundances of Lactobacillus-reuteri, Prevotellaceae, Paraprevotella, Christensenella and Streptococcus and decreased those of Peptostreptococcaceae and Romboutsia Bacteroides-sartorii. Besides, the improvement effect of autophagy activation on colitis disappears following gut microbiome depletion.

CONCLUSION

The therapeutic effects of rapamycin on extenuating experimental colitis may be related to the gut microbiota.

Seasonal Prevalence of Gastrointestinal Parasites in Macaques (Macaca thibetana) at Mount Emei Scenic Area in China

The aim of the study was to elucidate the prevalence of intestinal parasites in macaques at the Mt. Emei Scenic Area of Sichuan, China. A total of 168 fecal samples were collected from yellow (n = 31), black (n = 19), new (n = 57), Leidongping (n = 57) and Wuxiangang (n = 4) macaques from 2019 to 2020. The fecal samples were tested for various gastrointestinal parasites following the microscopic detection method. The results showed that the total prevalence rate of the intestinal parasite was 51.19% (86/168), whereas the intestinal parasite with the highest prevalence was Gongylonema spp. (26.79%) for helminth and Entamoeba spp. (18.45%) for protozoa. Interestingly, the highest prevalence of intestinal parasites was observed during the summer season (86.21%), and the lowest was observed during the winter season (7.14%). There was a positive correlation observed between the human contact frequency and total prevalence rate of the intestinal parasites (p < 0.05); however, there was no correlation between the human contact frequency and total prevalence of the intestinal parasites at different seasons (p > 0.05). In conclusion, the dominant parasites Gongylonema spp. and Entamoeba spp. cause various diseases that may be transmitted to humans and other animals; therefore, there is a need for a proper management system, such as parasite control measures and population protection in the Mt. Emei Scenic Area of Sichuan, China.

Parasitic copepod (Lernanthropus kroyeri) on caged sea bass (Dicentrarchus labrax): An estimation of abundance and internal infestation pressure

Infestation by parasitic copepods is a substantial problem in the cage culture of European sea bass (Dicentrarchus labrax). The Copepoda parasite, Lernanthropus kroyeri (Lernanthropidae), is one of the threats to the mariculture of sea bass. In the present study, we evaluated the data of abundance for L. kroyeri pre-adults and adult males (PAAM) and ovigerous adult females (AF_o ) to estimate the internal infection pressure (IIP) in the same cage environment. The sea bass infested by L. kroyeri was collected from grow-out sea cages located in Gulluk Bay (Turkey) in September and October 2019. Mean fish weight and length of sea bass were 75.79 ± 1.66 g and 21.40 ± 0.56 cm, respectively. The fixed lag method was used to predict the abundance of L. kroyeri adult females. The overall prevalence of L. kroyeri was 60%. The mean abundance of PAAM and AF_o varied from 0.8 ± 0.24 to 2.5 ± 0.67 and 2.9 ± 0.40 to 4.3 ± 0.55, respectively. The abundance of AF was strongly correlated with PAAM. The pattern of AF_o and PAAM was interpreted as an indication of the continuous infestation of L. kroyeri on sea bass. Our results showed that the correlation of AF_o abundance for five consecutive weeks was significant, representing the main determinative factor for the continuity of the parasitic load. In our approach, internal infestation pressure is the quantitative estimation of the potential infective copepodids, which are mainly characterized by AF abundance and the prevalence. We predicted that the internal infestation pressure could be high, even exceeding the 50.000 × 10⁶ potential infective copepodids for one sea cage with the fish density of 20 sea bass/m³ .

Mediterranean Aquaculture in a Changing Climate: Temperature Effects on Pathogens and Diseases of Three Farmed Fish Species

Climate change is expected to have a drastic effect on aquaculture worldwide. As we move forward with the agenda to increase and diversify aquaculture production, rising temperatures will have a progressively relevant impact on fish farming, linked to a multitude of issues associated with fish welfare. Temperature affects the physiology of both fish and pathogens, and has the potential to lead to significant increases in disease outbreaks within aquaculture systems, resulting in severe financial impacts. Significant shifts in future temperature regimes are projected for the Mediterranean Sea. We therefore aim to review and discuss the existing knowledge relating to disease outbreaks in the context of climate change in Mediterranean finfish aquaculture. The objective is to describe the effects of temperature on the physiology of both fish and pathogens, and moreover to list and discuss the principal diseases of the three main fish species farmed in the Mediterranean, namely gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax), and meagre (Argyrosomus regius). We will attempt to link the pathology of each disease to a specific temperature range, while discussing potential future disease threats associated with the available climate change trends for the Mediterranean Sea.

Identifying indicator species in ecological habitats using Deep Optimal Feature Learning

Much of the current research on supervised modelling is focused on maximizing outcome prediction accuracy. However, in engineering disciplines, an arguably more important goal is that of feature extraction, the identification of relevant features associated with the various outcomes. For instance, in microbial communities, the identification of keystone species can often lead to improved prediction of future behavioral shifts. This paper proposes a novel feature extractor based on Deep Learning, which is largely agnostic to underlying assumptions regarding the training data. Starting from a collection of microbial species abundance counts, the Deep Learning model first trains itself to classify the selected distinct habitats. It then identifies indicator species associated with the habitats. The results are then compared and contrasted with those obtained by traditional statistical techniques. The indicator species are similar when compared at top taxonomic levels such as Domain and Phylum, despite visible differences in lower levels such as Class and Order. More importantly, when our estimated indicators are used to predict final habitat labels using simpler models (such as Support Vector Machines and traditional Artificial Neural Networks), the prediction accuracy is improved. Overall, this study serves as a preliminary step that bridges modern, black-box Machine Learning models with traditional, domain expertise-rich techniques.

Parasitological diagnosis in food fish produced in a fish farm, in the Zona da Mata, Minas Gerais, southeastern Brazil

This study identified the parasitic species in juvenile freshwater finfishes during the fattening stage, from a fish farm located in the Zona da Mata (MG), southeastern Brazil, and revealed both macro and microscopical lesions in fish gills. A total of 172 juvenile fishes of different species (Oreochromis niloticus, Ictalurus punctatus, Ctenopharyngodon idella, Cyprinus carpio, Astyanax bimaculatus and Brycon amazonicus) were transported to a laboratory in São Paulo city. The fish were sedated and then euthanized for parasitological analysis. All fish were infected by at least one parasite species. Ten different species of parasites were identified: Apiosoma sp., Epistylis sp., Ichthyobodo sp., trichodinids, Piscinoodinium pillulare, Ichthyophthirius multifiliis, Tetrahymena sp., monogeneans, Centrocestus formosanus metacercariae, and Dermocystidium sp. The best management practices and lack of sanitary control were also discussed.

Trace Elements and Fatty Acid Profile of Argyrosomus regius (Asso, 1801) from Mediterranean Aquaculture

Although Argyrosomus regius (Asso, 1801) counts among the most appreciated and increasingly consumed fish species in Europe, little information is available on its flesh quality. This research concerns both healthy aquatic resource diversification and good nutritional quality. It is the first study to evaluate the quality of A. regius flesh from Mediterranean aquaculture. It aims to assess the concentration of 19 trace elements and to determine the fatty acid profile of this fish farmed in the Mediterranean Sea and to discuss human exposure risks. The nutritional intake of oligoelements (selenium (Se), zinc (Zn), and chromium (Cr)) and the mean concentrations of contaminants (arsenic (As), barium (Ba), cadmium (Cd), lead (Pb), and tin (Sn)) in A. regius muscles are, respectively, above and below recommended regulatory standards set by the international legislation. Additionally, the low fat content in its muscle mass and its high level of docosahexaenoic acid (C22: 6 n-3; DHA) and, to a lesser extent, eicosapentaenoic acid (C20: 5 n-3; EPA) confers satisfying nutritional qualities. This study allowed to conclude that meager can be considered as a source of seafood with good nutritional qualities for human health.

Temperature-dependent consumption of spiders by little brown bats (Myotis lucifugus), but not northern long-eared bats (Myotis septentrionalis), in northern Canada

Intraspecific variation in diet has been observed in many species, including the geographically widespread little brown bat (Myotis lucifugus (Le Conte, 1831)). Spider consumption by M. lucifugus is more common in northern regions of their distribution, possibly due to reduced availability of aerial prey during low temperatures. However, in previously studied northern regions, M. lucifugus was the only bat species captured. The purpose of our study was to examine whether there is overlap in the diet and morphology of M. lucifugus and the northern long-eared bat (Myotis septentrionalis (Trouessart, 1897)), a species that commonly gleans prey, in the Northwest Territories, Canada. There were significant differences in the dietary composition and wing morphology of the two species, suggesting partitioning of resources. Both species consumed spiders, although unlike M. septentrionalis, the probability of M. lucifugus consuming spiders was significantly greater at low temperatures. Myotis lucifugus demonstrated a different pattern of spider consumption than in other northern regions where it consumes spiders throughout the summer, suggesting the possibility of resource competition where M. lucifugus overlaps with M. septentrionalis. Further research is needed to determine whether arthropods are seasonally limiting at high latitudes and to examine how these species capture nonaerial prey, including spiders.