Bioaccumulation of Zn in Muscle and Brain Tissues of the African Catfish—Clarias gariepinus

Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising input of recalcitrant pollutants such as the heavy metals in aquatic habitats. This research investigated the presence and levels of Zn in muscle and brain tissues of C. gariepinus sourced from selected markets in Delta State. Replicate adult fish samples were obtained from seven market locations in Oleh, Asaba, Ekpan, Ogwashi-Ukwu, Okere, Abraka and Ughelli towns, labeled and taken to the laboratory in iced coolers. The presence and levels of the heavy metal were determined spectrophotometrically. Concentrations ranged from 0.015 - 0.19 (0.09 ± 0.02) mg/kg d.w. in muscle and 0.035 - 0.36 (0.16 ± 0.03) mg/kg d.w. in brain tissues, even as accumulation levels differed significantly (t = 0.005) between the tissues at p < 0.05. There was also significant locational heterogeneity in accumulations of the metal [F(100.97) > Fcrit(4.02)] at the 95% confidence limit;with least accumulation of 0.03 (±0.01) mg/kg d.w. recorded in fish samples obtained from Ughelli and maximum accumulation of 0.28 (±0.07) mg/kg d.w. recorded in those obtained from Oleh locations. However, levels were below the Food and Agricultural Organization and World Health Organization acceptable limits for Zn in edible fish. Results revealed that lipophilic brain tissues accumulated more heavy metal than muscle tissues. Since accumulation levels were low, they do not currently constitute public health risks to consumers in Delta State.

Alcohol consumption promotes arsenic absorption but reduces tissue arsenic accumulation in mice

Alcohol consumption alters gut microflora and damages intestinal tight junction barriers,which may affect arsenic(As)oral bioavailability.In this study,mice were exposed to arsenate in the diet(6μg/g)over a 3-week period and gavaged daily with Chinese liquor(0.05 or 0.10 mL per mouse per day).Following ingestion,78.0%and 72.9%of the total As intake was absorbed and excreted via urine when co-exposed with liquor at daily doses of 0.05 or 0.10 mL,significantly greater than when As was supplied alone(44.7%).Alcohol co-exposure significantly altered gut microbiota but did not significantly alter As biotransformation in the intestinal tract or tissue.Significantly lower relative mRNA expression was observed for genes encoding for tight junctions in the ileum of liquor co-exposed mice,contributing to greater As bioavailability attributable to enhanced As absorption via the intestinal paracellular pathway.However,As concentration in the liver,kidney,and intestinal tissue of liquortreated mice was decreased by 24.4%-42.6%,27.5%-38.1%,and 28.1%-48.9%compared to control mice.This was likely due to greater renal glomerular filtration rate induced by alcohol,as suggested by significantly lower expression of genes encoding for renal tight junctions.In addition,in mice gavaged daily with 0.05 mL liquor,the serum antidiuretic hormone level was significantly lower than control mice(2.83±0.59 vs.5.40±1.10 pg/mL),suggesting the diuretic function of alcohol consumption,which may facilitate As elimination via urine.These results highlight that alcohol consumption has a significant impact on the bioavailability and accumulation of As.