Role of niche and micro-habitat preferences in per- and polyfluoroalkyl substances occurrence in the gills of tropical lake fish species.

The present study has investigated per- and poly-fluoroalkyl substances (PFAS) in the gill tissues of various fish species inhabiting different trophic levels within Eleyele Lake, a tropical freshwater lake in Nigeria. The mean concentrations of PFAS congeners were determined, and their trends and patterns were analyzed across different trophic species. The results revealed variations in congener abundance and species-specific patterns that was influenced by habitat and niche preferences. Multivariate associations using canonical-correlation analysis (CCA) revealed distinct trends in the relationships between gill concentrations of specific PFAS congeners and different trophic groups. The strongest congener relationships were observed in the pelagic omnivore (Oreochromic niloticus: ON) with positive associations for 4:2 FTS, 9CL-PF3ONS, PFTDA, MeFOSA and PFHxS. The differences in congener profiles for the two herbivorous fish (Sarotherodon melanotheron (SM) and Coptodon galilaeus (CG)) reflect possible divergence in microhabitat and niche preferences. Furthermore, the congener overlaps between the herbivore (CG), and benthic omnivore (Clarias gariepinus: ClG) indicate a possible niche and microhabitat overlap. Our study provides valuable insights into the congener dynamics of PFAS at Eleyele Lake. However, the dissimilarity and overlapping PFAS congener profile in fish gills reflects the interplay of species niche preference and microhabitat associations. The present study highlights the need for further research to assess ecological risks and develop effective PFAS management strategies.

Occurrence, bioaccumulation and trophic dynamics of per- and polyfluoroalkyl substances in two tropical freshwater lakes.

We have investigated the occurrence, distribution, and biomagnification of per- and polyfluoroalkyl substances (PFAS) in two tropical lakes (Asejire and Eleyele) of Southwestern Nigeria, with contrasting urban intensities. Over an 8-month period, we sampled sediment and fish species (Clarias gariepinus: CIG; Oreochromis niloticus: ON; Coptodon guineensis: CG; Sarotherodon melanotheron: SM) across trophic levels, and analyzed various PFAS congeners, in addition to a select group of toxicological responses. While herbivores (SM) and benthic omnivores (CIG) at Asejire exhibited elevated levels of PFBS and PFOS, the pelagic omnivores (ON) showed a dominance of PFOS, PFDA, PFHxDA and EtFOSE in the muscle. At the Eleyele urban lake, PFAS patterns was dominated by PFBS, EtFOSE, PFPeS, PFOcDA and PFOS in the herbivores (SM, CG), EtFOSE, PFOS and PFBS in the pelagic omnivore (ON) and benthic omnivore (ClG). The estimated biomagnification factor (BMF) analysis for both lakes indicated trophic level increase of PFOS, PFUnA and PFDA at the suburban lake, while PFOS and EtFOSE biomagnified at the urban lake. We detected the occurrence of diSAMPAP and 9CL-PF3ONS, novel compounds not commonly reported, in PFAS studies at both lakes. The studied toxicological responses varied across trophic groups in both lakes with probable modulations by environmental conditions, trophic structure, and relative PFAS exposures in the lakes. The present study documents, for the first time in Nigeria, or any other African country, the role of urbanization on contaminant load into the environment and their implications for contaminant dynamics within the ecosystem and for aquatic food safety.

Modulatory effects of extract of Heinsia crinita against fructose/streptozotocin-induced oxidative stress in diabetic rat models.

Oxidative stress plays a crucial role in the development of type 2 diabetes and the associated microvascular and cardiovascular complications. In the study, we have investigated the effects of Heinsia crinita (H. crinita) extracts on lipid peroxidation and oxidative stress responses using diabetic rats. Type 2 diabetes was induced with 10 % fructose/40 mg/kg body weight streptozotocin (STZ). H. crinita extract was administered at 200 and 400 mg/kg body weight twice daily for 21 days, in addition to metformin (MET: 500 mg/kg body weight) control. Molecular docking analysis was performed to determine the binding affinity of H. crinita extracts to the DNA binding domains of peroxisome proliferator-activated receptor (Ppar) and retinoid x receptor (Rxr) protein crystal structures, showing different binding affinities for putative active compounds from the plant. Fasting blood glucose (FBG), body and organ weight changes were determined showing that H. crinita extract induced an anti-hyperglycemic effect in the treated animals, with changes (either decrease or increase) in liver and kidney weights. A decrease in mRNA expression of peroxisome proliferator-activated receptors (ppar), sterol regulatory element-binding protein 1 (srebp-1c), liver x-receptor (lxr), retinoid x receptors (rxr), cytochrome p45041 (cyp4a1) and acyl-CoA oxidase (acox1) in diabetic animals were observed, compared to the control. A dose-specific decrease or increase in antioxidant enzymes (superoxide dismutase: SOD, catalase: CAT, reduced glutathione: GSH, glutathione peroxidase: GPx) transcripts and activity levels were also observed. We also observed exposure-specific decrease or increase of malondialdehyde (MDA) levels. Our data suggested that H. crinita extract possesses protective effects against diabetes-induced oxidative stress. These effects might be attributed to their binding and activation of nuclear receptors, indicating their cellular mode of action that is comparable to MET.

Antimicrobial analysis of honey against Staphylococcus aureus isolates from wound, ADMET properties of its bioactive compounds and in-silico evaluation against dihydropteroate synthase.

BACKGROUND: One of the main challenges of wound healing is infection with multi-drug resistant (MDR) bacteria such as Staphylococcus aureus. The spectrum of antibiotics used to treat them is declining; thus, there is a need for alternatives. Our study was designed to evaluate the antimicrobial properties of honey, its pharmacokinetics (ADMET) properties and in-silico analysis of its bioactive compounds against dihydropteroate synthase of S. aureus using trimethoprim as control. METHODS: Standard protocols were employed in collection and preparation of samples, generation of canonical strings, and conduction of microbiological analyses. Bioactive compounds' ADMET properties were evaluated using the SWISSADME and the MCULE toxicity checker tools. The MCULE one-click docking tool was used in carrying out the dockings. RESULTS: The gas chromatography-mass spectrophotometry revealed twenty (20) bioactive compounds and was dominated by sugars (> 60%). We isolated a total of 47 S. aureus isolates from the wound samples. At lower concentrations, resistance to trimethoprim (95.74 to 100.00%) was higher than honey (70.21 to 96.36%). Only seven (7) isolates meet Lipinski's rule of five and ADMET properties. The docking scores of the bioactive compounds ranged from -3.3 to -4.6 while that of trimethoprim was -6.1, indicating better binding or interaction with the dihydropteroate synthase. The bioactive compounds were not substrates to P450 cytochrome enzymes (CYP1A2, CYP2CI9 and CYP2D6) and p-glycoprotein, indicating better gastrointestinal tract (GIT) absorption. CONCLUSION: The favourable docking properties shown by the bioactive compounds suggest they could be lead compounds for newer antimetabolites for management of MDR S. aureus.

Public health implications of endocrine disrupting chemicals in drinking water and aquatic food resources in Nigeria: A state-of-the-science review.

This state-of-the-science review is aimed at identifying the sources, occurrence, and concentrations of EDCs, including potential public health risks associated with drinking water and aquatic food resources from Nigerian inland waters. A total of 6024 articles from scientific databases (PubMed, Scopus, Web of science, ScienceDirect, Google Scholar, and African Journals Online) were identified, out of which, 103 eligible articles were selected for this study. Eleven (11) classes of EDCs (OCPs, PCBs, PBDEs, PAHs, BPA, OTs, PEs, PCs, PPCPs, sterols and n-alkanes) were identified from drinking waters, river sediments and aquatic food species from Nigerian rivers, showing that OCPs were the most studied and reported EDCs. Analytical methods used were HPLC, LC-MS/MS, GC-FID, GC-ECD and GC-MS with all EDCs identified to originate from anthropogenic sources. Carcinogenic, mutagenic, and teratogenic effects were the highest (54.4 %) toxicological effects identified, while reproductive/endocrine disruptive effects (15.2 %) and obesogenic effects (4.3 %) were the least identified toxicological effects. The targeted hazard quotient (THQ) and cancer risk (CR) were generally highest in children, compared to the adult populations, indicating age-specific toxicity. PEs produced the highest THQ (330.3) and CR (1.2) for all the EDCs in drinking water for the children population, suggesting enhanced vulnerability of this population group, compared to the adult population. Due to associated public health, wildlife and environmental risk of EDCs and their increasing concentrations in drinking water and food fish species from Nigerian inland waters, there is an urgent need for focused and strategic interventions, sensitization and policy formulation/implementation towards public health and aquatic food safety in Nigeria.

Toxicity assessment of Lemna solid waste dumpsite (Calabar, Nigeria) using different extraction methods and toxicological responses of PLHC-1 cells.

In the present study, we have investigated the effects of three (elutriate, polar and non-polar) different soil extraction methods from the Lemna solid waste dumpsite (Calabar, Nigeria) on the biotransformation, antioxidant and cellular defense responses of PLHC-1 cell line. Following a 48 h exposure period to different concentrations of each extract, the PLHC-1 cells were evaluated for enzymatic activities - glutathione peroxidase (Gpx), glutathione reductase (Gr), glutathione S-transferase (Gst), 7-ethoxy-, pentoxy-, and benzyloxyresorufin O-deethylase (EROD, PROD and BROD) and mRNA expressions for catalase (cat), gpx, gst, cyp1a, cyp3a, mammalian target of rapamycin (mtor), nuclear factor erythroid 2-related factor 2 (nrf2) and Kelch-like erythroid cell-derived protein (keap-1). Overall, our results showed parameter-, extract- and concentration-specific increases in transcripts and functional product levels for biotransformation, antioxidant and cellular defense/cytoprotective responses, compared with control. These responses were mostly characterized by a biphasic pattern of effects by either, increasing at low concentration, and thereafter decrease, as the concentration increases or vice versa, depending on the extract type. These observations paralleled soil contaminants (organics and inorganics) burden from the dumpsite. Principal component analysis (PCA) showed that cells treated with the non-polar extract produced more pronounced effects on the measured toxicological responses, compared with the polar and elutriate extracts. Thus, our data highlight peculiar risks to cells exposed to each soil extract, indicating complex and multiple chemical interactions with diverse functional groups that contaminants may have in mixture scenarios. Given the limitations and cost implications of contaminants analysis for the numerous soil- or sediment-bound compounds, we propose that this approach represents an analytical benchmark and endpoints for assessing the risk of complex environmental matrices such as soil and sediments, for ecotoxicological monitoring programs.

Detection and occurrence of microplastics in the stomach of commercial fish species from a municipal water supply lake in southwestern Nigeria.

Microplastics (MPs) are physical anthropogenic pollutants and their ability to act as contaminant vectors in biological matrices is of serious ecosystem and human health concern. In the present study, we have, for the first time, screened and detected MPs in the stomach of a select group of commonly consumed fish species from a municipal water supply lake (Eleyele) in Nigeria. A total of 109 fish samples consisting of eight (8) species: Coptodon zillii (CZ: n = 38), Oreochromis niloticus (ON: n = 43), Sarotheron melanotheron (SM: n = 19), Chrysicthys nigrodigitatus (CN: n = 3), Lates niloticus (LN: n = 3), Paranchanna obscura (PO: n = 1), Hemichromis fasiatus (HF: n = 1), and Hepsetus odoe (HO: n = 1) were collected between February-April, 2018. Fish stomach content was screened for the presence of MPs using the density gradient separation technique (NaCl hypersaline solution) and examined using a fluorescence microscope. MPs were present in all the species screened (except H. fasciatus) with a frequency of 69.7% positive individuals in the examined species. MP prevalence was highest in ON (34%) > CZ (32%) > SM (13%) > CN (6%) and 5% each, for PO HO, and LN. On average, 1-6 MPs with sizes ranging between 124 µm and 1.53 mm were detected per individual. However, the highest number (34) of MPs was detected in the stomach of SM. Principal coordinate analysis (PCA) identified ecological variables such as habitat, feeding mode, and trophic levels as critical factors that may determine and influence MP uptake in fish population. The PCA showed stronger association between fish habitat, feeding mode, and trophic level with MP size and number in the benthopelagic species (ON CZ and SM), compared to demersal species (PO CN HO and LN). Given that MPs can act as vectors for the transfer of pathogens and environmental contaminants (both legacy and emerging), in addition to direct health risks to aquatic organisms, our findings raise concerns on the potential human/wildlife health effects of MPs in these economically and ecologically important food fishes.

Biotransformation and oxidative stress responses in relation to tissue contaminant burden in Clarias gariepinus exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria.

In this study, we have investigated biotransformation and oxidative stress responses in relation to tissue contaminant burden in the African sharptooth catfish (Clarias gariepinus) exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria. Fish were exposed to simulated leachate, diluted to 0:0 (negative control), 1:10, 1:50, 1:100 and phenanthrene (a PAH: 50 µg/L used as a positive control) for 3, 7 and 14 days. Hepatic transcripts for cat, sod1, gpx1, gr, gst, cyp1a, cyp2d3, and cyp27 were analyzed by real-time PCR, while enzymatic assays for ethoxyresorufin O-deethylase (EROD), buthoxyresorufin O-deethylase (BROD), methoxyresorufin O-deethylase (MROD), pentoxyresorufin O-deethylase (PROD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), uridine diphospho-glucuronosyltransferase (UDPGT) and lipid peroxidase (LPO) were measured using standard methods. In addition, protein expression for CYP1A, CYP3A and metallotheionin (MT) were measured by immunoblotting. Fish muscle samples were analyzed for selected group of contaminants after 14 days exposure showing significantly high uptake of heavy metals (Cd, Hg and Pb), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorophenols, organochlorine (OC) and organophosphate pesticides in exposed fish. We observed significant concentration- and time-specific increases in biotransformation and oxidative stress responses at transcript and functional (enzyme and protein) levels, that paralleled tissue contaminants bioaccumulation patterns, after exposure to the simulated leachates. Our results highlighted the potential environmental, wildlife and public health consequences from improper solid waste disposal. In addition, it also provides a scientific basis for local sensitization and inform legislative decisions and policy formulation towards sustainable environmental management of solid wastes in Nigeria and other developing countries.

Contaminant levels and endocrine disruptive effects in Clarias gariepinus exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria.

Solid waste dumpsites (SWDs) and landfills are significant sources of emerging contaminants to terrestrial and aquatic ecosystems. We have studied the endocrine disruptive effects of simulated leachate from a solid waste dumpsite in Calabar, Nigeria. Juvenile C. gariepinus were exposed to simulated leachate, diluted to 0:0 (control), 1:10, 1:50, 1:100 for 3, 7 and 14 days. In addition, 17ß-estradiol (E2: 100 µg/L)-exposed positive control group was included. Hepatic transcripts for the genes encoding vitellogenin (vtg), estrogen receptor-α (er-α), and aromatase (cyp19a1) were analyzed by real-time PCR. Protein expression for Vtg and Cyp19 were measured by immunoblotting and plasma steroid hormones (testosterone: T and E2) were measured using enzyme immunoassay (EIA). Soil samples from the dumpsite were analyzed for selected group of contaminants showing that DEHP was the only detected phthalate ester (PE) at 1300 ±â€¯400 ng/g. Further, perfluoroalkyl substances (PFASs) such as PFBS, PFOS, PFHxA, PFOA, PFNA, PFDA, PFUnDA and PFDoDA were detected in the soil samples from the dumpsite. We observed significant and apparent concentration-dependent increases in mRNA (vtg, er-α, and cyp19a1) and their corresponding functional protein products, after exposure to the simulated leachates. Further, the simulated leachate produced concentration-specific changes in plasma E2 and T levels. In general, the estrogenic endocrine and reproductive alterations in the exposed fish may directly be attributed to the PFASs and DEHP detected at the dumpsites. However, in addition to PFASs and DEHP, there could be other estrogenic contaminants in the leachate. Given the rapid utilization, for residential purposes, and increases in human settlement in areas around the Lemna SWDs, this study provides a direct cause-and-effect evidence of the potential contaminants at the dumpsite with significant environmental and human health consequences.

Sex-differences in physiological and oxidative stress responses and heavy metals burden in the black jaw tilapia, Sarotherodon melanotheron from a tropical freshwater dam (Nigeria).

Black jaw tilapia (S. melanotheron) collected from Awba Dam (a watershed recipient of effluents from anthropogenic sources) was analysed for biological responses and trace metal burden with the aim of evaluating sex differences in these responses as a measure of environmental and biota health status. Concentration of heavy metals in fish muscle were analysed and showed values above WHO permissible limits for food. Physiological and biochemical responses (AST, ALT, ALP, total protein, albumin, globulin, BUN, Na+, K+ and creatinine) showed apparent sex-related differences. Among antioxidant defence system, mt mRNA and proteins showed higher levels in male S. melanotheron. CAT and GPx activities were significantly higher in males than in female fish, while the corresponding mRNA showed an opposite trend with higher transcripts in females than males. Further, while GST activity was apparently higher in females, GR activity was significantly higher in males, compared to female fish. ZnCu-sod mRNA showed significantly higher transcript levels in males, than females. Overall, the trend in these biological responses showed direct relationship with heavy metal concentrations in fish muscle and sediment. These relationships were revealed using PCA that produced significant groupings between physiological, biochemical and oxidative stress variables and muscle/sediment trace element burden. Specifically, the PCA biplots showed that these biological variables were due to the presence of the heavy metals in the dam. Therefore, the sex differences in the measured cellular adaptations of S. melanotheron in relation to the toxic conditions at the dam may have significant consequences on osmotic balance and cellular processes that regulate biochemical/antioxidant responses towards metabolism, behaviour, growth, reproduction and survival of Awba dam resident fish species. Thus, these responses should be compared to a suitable reference site to discern the extent of effects of the Awba Dam biota for monitoring purposes.