Mucociliary transport, differential white blood cells, and cyto-genotoxicity in peripheral erythrocytes in fish from a polluted urban pond

Abstract

The present study evaluated the water quality of a polluted pond through the analysis of in vitro mucociliary transport, hematological parameters, and biomarkers of cyto-genotoxicity in the Nile tilapia (Oreochromis niloticus). Blood and mucus samples were collected from ten specimens from the polluted pond and from ten specimens from a control area. The fish were anesthetized with 3% benzocaine, mucus was collected directly from the gills, and blood was drawn from the caudal artery. Blood smears were stained using the May-Grünwald Giemsa process for the differential leukocyte counts and to determine the frequency of leukocytes, thrombocytes, erythroblasts, micronuclei, and nuclear abnormalities. The results revealed low transportability in vitro, a high percentage of monocytes and eosinophils, and increased frequency of leukocytes and nuclear abnormalities in fish from the polluted pond. However, the frequency of thrombocytes and erythroblasts and the percentage of lymphocytes and neutrophils were significantly lower. It is possible to conclude that changes in fish are due to poor water quality and that these non-destructive biomarkers can be used for the biomonitoring of aquatic environments vulnerable to contamination.

Time-dependent hematological responses of Nile tilapia Oreochromis niloticus exposed to an estuarine contaminated water

“…Studies have shown that exposure to polluted water causes anemia in fish with a decrease in hemoglobin concentration, hematocrit, and total circulating erythrocytes (Seriani et al 2010, Saleh & Marie 2016). However, contrary to previous studies that collected fish in situ (Seriani et al, 2010(Seriani et al, , 2013Silva et al, 2018), O. niloticus experimentally exposed for 72h and 120h to the contaminated water from Santos-São Vicente Estuary did not present an anemic picture. Once red blood cells account for gas transport in blood, fish erythrocytes are quite sensitive to changes in dissolved oxygen concentration, as a compensatory response to hypoxic environments (Sweilum, 2006;Cruz, Prado, Maciel, & Couto, 2015), a condition usually found in polluted waters by domestic organic effluents.…”

“…Similar results were reported by Seriani et al (2012), where O. niloticus exposed for 10 days to different selenium concentrations presented increased leukocyte types compared to the collection performed on the third day. Also, samples of O. niloticus collected in a polluted artificial lake showed increased total leukocyte number, associated with increased monocytes, eosinophils, and the presence of erythrocyte nuclear abnormalities, which was accompanied by the reduction of neutrophils, lymphocytes, and erythrocytes (Silva et al, 2018). Leukocytosis was also observed in fish collected in polluted areas, relative to reference values, as detected in Arius thalassinus species from the Red Sea Coast of Hodeida, Republic of Yemen (Saleh & Marie, 2016),…”

“…Xenobiotics with immunotoxic potential might promote not only the suppression but also the stimulation of the immune system, modifying the extent of immune responses (Burns-Naas, Meade, & Munson, 1996). The cellular apoptosis (Schrek & Tort, 2016), depression of leucopoiesis centers (Seriani et al, 2011), and leukocytes mobilization from the bloodstream to damaged tissues (Saleh & Marie, 2016;Silva et al, 2018) have been related to the immunosuppression seen in fish exposed to xenobiotics such as the pesticide diazinon (Alishahi, Mohammadi, Mesbah, & Razi, 2016), and metals as lead, copper, cadmium and zinc (Witeska, 2005). Thus, the immunosuppression can make fish living in impacted water bodies immunologically susceptible to infections and diseases (Yada & Tort, 2016).…”

Application of haematology parameters for health management in fish farms

“…261 The function of eosinophils is still not well understood, but eosinophils certainly have phagocytic functions. 262,263 Roberts (1989) found a correlation between the number of these cells and the activity of inflammatory and macrophage cells. 264 In cases of acute tissue damage or pathogen infection, a large number of eosinophils are non-specifically aggregated in the lesion to engulf pathogens and cause tissue damage.…”

“…The cell is round with a larger nucleus, rod‐shaped, kidney‐shaped or semicircular, occasionally dichotomous, and located on one side of the cell 261 . The function of eosinophils is still not well understood, but eosinophils certainly have phagocytic functions 262,263 . Roberts (1989) found a correlation between the number of these cells and the activity of inflammatory and macrophage cells 264 .…”