Effect of emerging pollutants on the gut microbiota of freshwater animals: Focusing on microplastics and pesticides.

In recent years, emerging environmental pollutants have increasingly endangered the health of freshwater organisms. The gut microbiota exhibits sensitivity to medications, dietary factors and environmental pollutants, rendering it a novel target for toxicological studies. The gut microbiota can be a potential exposure route affecting the host's health. Herein, we review the current knowledge on two different but concurrent pollutants, microplastics and pesticides, regarding their impact on the gut microbiota, which includes alterations in microbial composition, gene expression, function, and health effects in the hosts. Moreover, synergetic interactions between microplastics and pesticides can exacerbate dysbiosis and health risks. We discuss health-related implications of gut microbial changes based on the consequences in metabolism, immunity, and physiology function. Further research is needed to discover the mechanisms underlying these effects and develop strategies for mitigating their harmful impacts on freshwater animals.

Dietary lysine requirements of Colossoma macropomum (Cuvier, 1818) based on growth performance, hepatic and intestinal morphohistology and hematology.

This study aimed to determine the dietary lysine requirements of juvenile Colossoma macropomum tambaqui based growth performance, hepatic and intestinal morphohistology and hematology. Tambaqui were fed with levels of 6.60, 9.72, 12.84, 15.96, 19.08, and 22.20 g/kg of total lysine and those who received 15.96 g/kg dietary lysine showed higher final weight (p= 0.001) and optimized feed conversion ratio (p= 0.001). Morphohistological modifications (presence of fat droplets) were present in livers of fish fed with low levels of lysine. In the morphohistology of the intestine, the diets influenced the density of the intestinal, cell layers, height and perimeters of the villi and acid mucin secretion by the goblet cells. In the proximal intestine, mucosa layer density was greater at the level of 15.96 g/kg (p= 0.001). In the middle intestine, height (p= 0.001) and perimeter (p= 0.001) of the villi were greater at low levels of lysine (respectively, 9.72 and 12.84 g/kg dietary lysine). No differences were found for the hemoglobin, hematocrit, erythrocytes, MCV, MCH, MCHC, thrombocytes and leukocytes differentiated of fish fed with experimental diets (p>0.05). The biochemical responses were affected by the diet, both in plasma concentration (protein and cholesterol; p<0.05), and in muscle (ash and moisture; p<0.05). In conclusion, the dietary requirement for lysine for tambaqui juveniles was estimated to be 15.4 - 15.6 g/kg of diet (5.7% -5.8% dietary protein).

Proximate and Nutritional Content of Rainbow Trout (Oncorhynchus mykiss) Flesh Cultured in a Tropical Highland Area

Abstract The present study was performed to assess the proximate and nutrient content of rainbow trout flesh, cultured in the Doi Inthanon Fisheries Research Unit, Chiang Mai Inland Fisheries Research and Development Center, Thailand. 240 fish were randomly distributed across 12 cages with 20 fish cage-1. Sixteen individual fish from each cage were randomly collected at different ages of 10, 12 and 24 months. Body composition, pH, water-holding capacity, shear force, collagen content analysis, sensory, lipid oxidation, and fatty acids profile were evaluated. The results indicated that body composition and carcass length were significantly higher in fish aged 24 months, except for carcass and viscero-somatic index percentages (P ≤ 0.05). Fish at 24 months showed significantly higher pH, moisture, fat, shear force, thiobarbituric acid reactive substances, and total collagen content values than fish at 10 and 12 months (P ≤ 0.05). However, protein percentage, sensory measurement and water-holding capacity were significantly higher in younger fish at 10 and 12 months. The average lipid content and n-6/n-3 ratios were significantly greater in fish at 12 months and in ventral fillets (P ≤ 0.05). However, polyunsaturated fatty acids: saturated fatty acid ratio was higher in fish at 24 months and in dorsal fillets. In conclusion, rainbow trout cultured in sub-tropical, montane conditions can be valuable sources of protein, unsaturated fatty acids, eicosapentaenoic acids, and docosahexaenoic acids.

A potential microRNA regulation of immune-related genes in invertebrate haemocytes.

Bivalve mollusks have been employed as sentinel organisms in environmental health programs due to their sedentary lifestyle, filter-feeding behavior and their ability to accumulate pathogens or toxin molecules inside tissues. Endocrine disrupting chemicals (EDCs) can be up taken and bioaccumulated, and due to sensibility of mollusks to these EDCs, being able to cause immune alterations. Recently, microRNAs (miRNAs) were shown to be involved in modulation and buffering developmental processes against the effects of environmental alterations and pathogenic microorganisms. Moreover, it is suggested that this miRNAs are incorporated into the estrogen-controlled immune network, regulating mechanism of immune gene expression at the posttranscriptional level, modulating immune responses as phagocytosis, redox reaction and apoptosis in bivalve haemocytes. Thus, miRNAs can be used as biomarkers that specifically elucidate immunotoxic effects caused by exogenous biotic or abiotic factors, and can act as useful tools in integrated monitoring environmental health programs. In this review, we aim to describe the investigations that have been carried out on miRNAs in bivalve mollusks, especially those associated with immune responses against infectious agents and xenobiotic exposure.

An approach to the study of the immunity functions of bivalve haemocytes: Physiology and molecular aspects.

The Mediterranean mussel Mytilus galloprovincialis is an ecologically and economically important species. It has been used in programs of monitoring of pollution, since it is sessile organism that is capable of accumulating pollutants in tissues through filter feeding. Due to an increase of pollutants in the environment, marine mussels present physiological alterations that compromise their innate immune system, which can latter lead to opportunistic diseases. The haemocytes are the cells in charge of the immune response in the Mediterranean mussel and in other mollusks. In this review, we summarize the physiological and genetic response capacity of these immune cells to the presence of xenobiotics, pathogens and the interplay. The identification of the basic mechanisms of immunity and their modulation in mussels can give important information for the possible utilization of this species as an invertebrate model for studies on innate immunity, future immunotoxicological studies, and predict changes in the community for the future.

Potential Use of Polysaccharides from the Brown Alga Undaria pinnatifida as Anticoagulants

Undaria pinnatifida (U. pinnatifida) is a highly invasive species and has caused concern all over the world because it has invaded coastal environments, has the potential to displace native species, significantly alters habitat for associated fauna, and disturbs navigation. Any attempt to eradicate it would be futile, owing to the elusive, microscopic gametophyte, and because the alga thrives in sites rich in anthropic activities. Venice Lagoon is the largest Mediterranean transitional environment and the spot of the highest introduction of non-indigenous species, including U. pinnatifida, which is removed as a waste. We demonstrated that polysaccharide extracts from U. pinnatifida have an anticoagulant effect on human blood in vitro and are not cytotoxic. The results obtained by PT (normal values 70-120%) and APTT (normal values 28-40s) assays were significantly prolonged by the polysaccharide extracts of U. pinnatifida, therefore algal extracts are ideal candidates as antithrombotic agents.

Copper Induced Lysosomal Membrane Destabilisation in Haemolymph Cells of Mediterranean Green Crab (Carcinus aestuarii, Nardo, 1847) from the Narta Lagoon (Albania)

ABSTRACTDestabilisation of blood cell lysosomes in Mediterranean green crabCarcinus aestuarii was investigated using Neutral Red Retention Assay (NRRA). Crabs collected in Narta Lagoon, Vlora (Albania) during May 2014 were exposed in the laboratory to sub-lethal, environmentally realistic concentrations of copper. Neutral Red Retention Time (NRRT) and glucose concentration in haemolymph of animals were measured. The mean NRRT showed a significant reduction for the animals of the treatment group compared to the control one (from 118.6 ± 28.4 to 36.4 ± 10.48 min, p<0.05), indicating damage of lysosomal membrane. Haemolymph glucose concentration was significantly higher in the treatment group (from 37.8 ± 2.7 to 137.8.4 ± 16.2 mg/dL, p<0.05) than in control group, demonstrating the presence of stress on the animals. These results showed thatC. aestuarii could be used as a successful and reliable bioindicator for evaluating the exposure to contaminants in laboratory conditions. NRRA provides a successful tool for rapid assessment of heavy metal pollution effects on marine biota.