Acute phenanthrene toxicity to juvenile diploid and triploid African catfish (Clarias gariepinus): Molecular, biochemical, and histopathological alterations

Effects of heavy pollution in different water bodies on male rainbow trout (Oncorhynchus mykiss) reproductive health

This research aimed to investigate the influence of heavy metals on the reproductive health of rainbow trout (Oncorhynchus mykiss) captured from two locations, Verinag (S1) and Panzath (S2). Sixty (n. 60) mature rainbow trout samples (30 from each site) with body weights ranging from 400 to 650 g were collected from Verinag hatchery, which was less polluted (S1), and Panzath hatchery, which was more polluted (S2). The findings revealed significant differences between the two sites, S1 (less polluted) and S2 (more polluted), as well as significant variations within the tissues. Iron (Fe) and Zinc (Zn) were found to be highest in sampling water as well as in fish tissues sampled from S2 sites. Similarly, concerning S1 captured fishes, histopathological examination of testes from S2 captured fish was found. Testicular abnormalities that included disorganization of the seminiferous tubules, reduction in the number of germ cells (sperm cells, spermatozoa), vacuolization, and large empty areas in the seminiferous epithelium were found. In testicular cells, the frequency of apoptotic cells collected from S2 water increased significantly (P < 0.05). SOD, catalase, and glutathione peroxidase activity increased in S1 captured fishes but decreased in S2 captured fishes. MDA levels gradually increased in S2 captured fish, and the degree of heavy metal stress was positively correlated (P < 0.05). In male rainbow trout, testosterone and 11-ketotestosterone levels increased substantially in S1 captured fishes. While the fatty acids of testes in S2 fishes decreased with respect to S1 fishes. In conclusion, S2 captured fish suffered more damage due to heavy metals including cellular damage, apoptosis, oxidative damage, and altered steroid hormones when compared to fish from S1 waters.

Characterization and implication of microplastics on riverine population of the River Ravi, Lahore, Pakistan

Microplastic (MP) pollution in the aquatic environment is an emerging subject worldwide. So far, very few investigations have been reported on the riverine fish population. This study investigated the implications of microplastics for three freshwater fish species (Labeo rohita, Cirrihinus mrigala, and Sperata seenghala) as bioindicators of this pollution. Raman spectroscopy was used to confirm MP polymer type and their distribution in water, sediments, and in different organs (gut, gills, liver, and muscles) of Labeo rohita, Cirrihinus mrigala, and Sperata seenghala collected from River Ravi at two sites (site I, Dhand Nano Dogar and site II, Jhamra). These selected sites were situated predominantly near agricultural lands and received polluted water from nearby sewerage and industries that represented potential sources of microplastic pollution. Histological analysis was combined with Raman spectroscopy to assess the effects of MPs on fish organs. MPs were identified in water and sediment samples with an average load (per 0.5 L or per 0.5 kg) of 33 items and 64 items for water and sediments at site I and 27 items and 19 items at site II, respectively. Of total MPs identified, 56.9% were found in bottom feeder C. mrigala, 37.91% in column feeder L. rohita, and 5.21% in S. seenghala at site I while at site II 60% were found in C. mrigala, 29% in L. rohita and 10.34% in S. seenghala. This was linked with more plastic accumulation in sediments from the nearby residential sewerage and industrial effluent flow. In this study, the identified MPs polymers were in the order of polyvinyl chloride (PVC) > polystyrene (PS) > propylene (PP) > polyethylene (PE). Among plastic shapes, fiber (58%) was the dominant plastic in water followed by fragment (21%), sheet (12%), and cube (9%). In sediment, the fragment was the common plastic shape with 51% followed by fiber (28%), sheet (19%), and cube (2%). Fragments (62.9%) in water and fibers (68.4%) in sediments were abundant at site 2. Microplastic mean occurrence in organs was in the order of gut > gills > muscles > liver at both sites. Significant histological alterations were observed in all three species including intestinal edema, hyperplasia, hepatocyte infiltration, accumulation of lipid droplets in the liver, lamellar fusion and breakage in gills, and muscle fiber necrosis. This study showed MP occurrence in the selected freshwater fishes, so further research is needed to assess plastic pollution in the riverine fish population of Pakistan. This study appeared to be the first in the selected area, as no significant information regarding plastic pollution in that riverine system was found when this study was conducted.

Heavy metals and parasitological infection associated with oxidative stress and histopathological alteration in the Clarias gariepinus

The goal of this study was to assess the harmful effects of heavy metal accumulation on Clarias gariepinus (catfish) in two different polluted areas in the Al Sharkia governorate and assess the impact on oxidative stress and histological changes. The results revealed a highly significant difference in heavy metal levels in the water and inside fish tissues (liver and gonads) between the two sites. The total prevalence of parasitic infection was at the highest percentage in area B, in addition to severe histopathological damage to the liver and the gonads. Findings show that the total prevalence of parasitic infection is associated with uptake of metals, depleted antioxidant activity, and incidence of lipid peroxidation in tissue.

Long-term exposure to p-Nitrophenol induces hepatotoxicity via accelerating apoptosis and glycogen accumulation in male Japanese quails

p-Nitrophenol (PNP) is the main end product of organophosphorus insecticides and a derivative of diesel exhaust particles. In addition to its unfavorable impact on reproductive functions in both genders, it also has various harmful physiological effects including lung cancer and allergic rhinitis. The identification of the cellular readout that functions in metabolic pathway perpetuation is still far from clear. This research aimed to study the impact of chronic PNP exposure on the health condition of the liver in Japanese quails. Quails were exposed to different concentrations of PNP as follows: 0.0 (control), 0.01mg (PNP/0.01), 0.1mg (PNP/0.1), and 1mg (PNP/1) per kg of body weight for 2.5 months through oral administration. Liver and plasma samples were collected at 1.5, 2, and 2.5 months post-treatment for biochemical, histopathology, and immunohistochemistry assessment. The plasma aspartate aminotransferase (AST) level was assessed enzymatically. The livers were collected for histopathology, glycogen accumulation, proliferating cell nuclear antigen (PCNA), and apoptosis assessment. Our results revealed an irregularity in body weight due to the long-term exposure of PNP with a significant reduction in liver weight. PNP treatment caused histopathological alterations in the hepatic tissues which increased in severity by the long-term exposure. The low dose led to mild degeneration with lymphocytic infiltration, while the moderate dose has a congestion effect with some necrosis; meanwhile severe hepatocyte degeneration and RBCs hemolysis were noticed due to high dose of PNP. Glycogen accumulation increased in hepatocytes by prolonged exposure to p-Nitrophenol with the highest intensity in the group treated by the high dose. Moderate and high doses of PNP resulted in a significant increase in apoptosis and hepatocytes' proliferation at the different time points after treatment. This increase is markedly notable and maximized at 2.5 months post-treatment. The damage occurred in a time-dependent manner. These changes reflected on the plasma hepatic enzyme AST that was clearly increased at 2.5 months of exposure. Therefore, it could be concluded that PNP has profound toxic effects on the liver in cellular level. Taking into consideration the time and dose factors, both have a synergistic effect on the accumulation of glycogen, apoptosis, and cellular proliferation, highlighting the power of cellular investigation which will potentially open the door for earlier medical intervention to counteract this toxicity. Collectively, PNP could have critical hurtful effects on the health of human beings, wild animals as well as livestock.

Microplastics as vectors of the antibiotics azithromycin and clarithromycin: Effects towards freshwater microalgae

Water pollution due to microplastics (MPs) is recognized as a major anthropogenic impact. Once MPs reach the ecosystems, they are exposed to a variety of other pollutants, which can be sorbed on them, transported and eventually desorbed. In this work, we tested the hypothesis that MPs can behave as conveyors for delivering chemicals toxic to aquatic microorganisms by investigating the vector role of MPs of polyethylene terephthalate (PET), polylactic acid (PLA), polyoxymethylene (POM) and polystyrene (PS) to the macrolide antibiotics azithromycin (AZI) and clarithromycin (CLA). AZI and CLA were chosen, as they are included in the Watch List for EU monitoring concerning water policy by Decision (EU) 2018/840. MPs were loaded in contact with 500 μg/L of AZI or 1000 μg/L of CLA. Results showed that both antibiotics were sorbed on all tested MPs. The more hydrophobic AZI was sorbed in higher proportion than CLA. Both antibiotics were desorbed from MPs upon contact with water with percentages between 14.6 ± 2.6% for AZI and 1.9 ± 1.4% for CLA of the concentrations to which the MPs were initially exposed. Virgin MPs were not toxic to the cyanobacterium Anabaena sp. PCC7120. However, antibiotic-loaded MPs significantly inhibited the growth and chlorophyll content of the cyanobacterium. Most of the sorbed antibiotics became released upon contact with cyanobacterial cultures, which was the cause for the observed toxicity. Therefore, MPs can play a role as vectors of antibiotics in freshwaters systems affecting the basic trophic level of photosynthetic microorganisms.

Effect of temperature on phenanthrene accumulation from hydraulic fracturing flowback and produced water in rainbow trout (Oncorhynchus mykiss)

Hydraulic fracturing has become widely used in recent years to access vast global unconventional sources of oil and gas. This process involves the injection of proprietary mixtures of water and chemicals to fracture shale formations and extract the hydrocarbons trapped within. These injection fluids, along with minerals, hydrocarbons, and saline waters present within the formations being drilled into, return to the surface as flowback and produced water (FPW). FPW is a highly complex mixture, containing metals, salts and clay, as well as many organic chemicals, including polycyclic aromatic hydrocarbons such as phenanthrene. The present study sought to determine the effects of temperature on the accumulation of phenanthrene in rainbow trout (Oncorhynchus mykiss). This model organism resides in rivers overlapping the Montney and Duvernay formations, both highly developed formations for hydraulic fracturing. Rainbow trout acclimated to temperatures of 4, 13 and 17 °C were exposed to either 5% or 20% FPW, as well as saline mixtures representing the exact ionic content of FPW to determine the accumulation of radiolabelled ¹⁴C phenanthrene within the gill, gut, liver and gallbladder. FPW exposure reduced the overall accumulation of phenanthrene in a manner most often similar to high salinity exposure, indicating that the high ionic strength of FPW is the primary factor affecting accumulation. Accumulation was different at the temperature extremes (4 and 17 °C), although no consistent relationship was observed between temperature and accumulation across the observed tissues. These results indicate that several physiological responses occur as a result of FPW exposure and water temperature change which dictate phenanthrene uptake, particularly in the gills. Temperature (and seasonality) alone cannot be used to model the potential accumulation of polycyclic aromatic hydrocarbons after FPW spills.

Transcriptome changes of Takifugu obscurus liver after acute exposure to phenanthrene

Phenanthrene (Phe) is a model compound in polycyclic aromatic hydrocarbon (PAH) research. Reportedly, Phe treatment induced oxidative stress and histological disorders to Takifugu obscurus liver. In this study, to further explore the molecular responses of T. obscurus liver to Phe exposure, transcriptome sequencing was applied to compare mRNA transcription profiles between Phe treatment and the control. Compared with the control, 1,581 and 1,428 genes were significantly upregulated and downregulated in Phe treatment, respectively. Further analysis revealed that Phe treatment mainly upregulated genes in Ras-MAPK and PI3K-akt signaling pathways, which represented insulin resistance and further activated the FOXO signaling pathway. The triacylglycerol biosynthesis was promoted but the gluconeogenesis process was inhibited in response to Phe treatment, demonstrating that Phe exposure disturbed the sugar and lipid metabolism. Moreover, Phe treatment upregulated the Apelin-APJ and ErbB signaling pathways, promoting angiogenesis in T. obscurus liver. Insulin resistance, promoted triacylglycerol biosynthesis, and angiogenesis might explain the molecular mechanisms underlying carcinogenic toxicity of Phe. Overall, this study provides new insights to understand the environmental risk of Phe to fishes.

Toxic effects of copper sulfate on diploid and triploid fin cell lines in Misgurnus anguillicaudatus

The effects of different concentrations of copper sulfate on diploid and triploid fin cell lines (named DIMF and TRMF, respectively) in Misgurnus anguillicaudatus were studied. The LC₅₀ of copper sulfate estimated by an MTT assay was 268.39 in DIMF cells, and 311.54 μmol/L in TRMF cells, respectively. Activity of superoxide dismutase (SOD) in DIMF cells gradually increased as the concentration of copper sulfate increased (up to 200 μmol/L), and then gradually decreased. SOD activity in triploid loach fin cells, as well as glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) activity in both diploid and triploid cells, decreased as the concentration of copper sulfate increased, which suggested that excessive copper exposure at the concentrations tested in this study was detrimental to anti-oxidative capability. In general, SOD, GST and GSH-Px activity was higher in triploid fin cells than in diploid cells. DNA breaks were observed by comet assays after 24 h exposure to 400 and 800 μM copper; DNA percent in the comet's tail was lower in TRMF than in DIMF. Ultrastructurally, there were no significant differences in the organelles of both cells, although a higher number of vesicles were observed in TRMF cells after copper exposure. Pathological changes induced by copper sulfate were similar in DIMF and TRMF cells, and were indicative of cell necrosis. Results above suggested that excessive copper sulfate exposure would lead to antioxidant enzymes activity reduction, along with antioxidant defenses disruption and superoxide radicals increasing, and then to DNA damage, ultrastructural changes and necrosis features in DIMF and TRMF M. anguillicaudatus fin cells. Triploid cell lines had higher resistance to copper than their diploid counterparts especially at higher concentrations of copper due to larger cells and higher intracellular content of detoxification enzymes to resist the toxicity of heavy metals.

Hepatotoxic responses of 4-nonylphenol on African catfish (Clarias gariepinus): antixoidant and histochemical biomarkers

4-Nonylphenol (NP) toxicity in fish attracts much attention due to its ability in targeting several organs; however, the researches regarding its potential hepatotoxicity are conflicting and still require further investigation. Therefore, the objective of this study is to focus on this issue from the histophysiological point of view using NP intoxicated African catfish (Clarias gariepinus) as a model of hepatotoxicity. Twelve adult fish (6 per group) were divided into two groups; the first was considered as a control and the second was exposed to NP dissolved in water at a dose of 0.1 mg/kg BW for 3 weeks. A significant reduction in the hepatic alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase levels was observed in NP-exposed fish. Concerning the oxidant/antioxidant balance, a significant depletion in superoxide dismutase, catalase, and glutathione peroxidase was found along with a significant elevation in total peroxide and malondialdhyde. The histopathological examination of the hepatic tissues revealed that NP had marked hepatotoxic effects including hepatitis, centrilobular and focal hydropic and fatty degeneration, fatty change (steatosis), hepatic coagulative necrosis, and nuclear alterations in addition to apoptosis of hepatocytes and necrosis of endothelial cells. Depletion of the glycogen and increased in pigments (lipofuscin and hemosiderin) content in the hepatocytes were also recorded. Hemosiderosis and proliferation of the connective tissue around the blood vessels and branches of bile ducts and in the portal areas were also observed. In light of these findings, it was concluded that NP has a well-defined hepatotoxic impact paving the road towards other studies to investigate other detrimental cyto-physiological influences of this aquatic pollutant.

Combined toxicity of endosulfan and phenanthrene mixtures and induced molecular changes in adult Zebrafish (Danio rerio)

Individual and combined toxicities of endosulfan (ENDO) with phenanthrene (PHE) were evaluated using zebrafish (Danio rerio) adults. The 96-h LC₅₀ values for ENDO and PHE were 4.6 μg L^-1 and 920 μg L^-1, respectively. To evaluate the mixture toxicity, LC₁₀ and LC₅₀ concentrations were grouped into four combinations as ENDO-LC₁₀ + PHE-LC₁₀, ENDO-LC₁₀ + PHE-LC₅₀, ENDO-LC₅₀ + PHE-LC₁₀, and ENDO-LC₅₀ + PHE-LC₅₀, and their acute toxicities were determined. The combination of LC₅₀-ENDO and LC₁₀-PHE exhibited a synergistic effect. In addition, acetylcholinesterase activity decreased in zebrafish bodies exposed to ENDO with or without PHE. Combined treatments induced higher glutathione S-transferase activity compared to individual treatments. Carboxylesterase activity increased in both heads and bodies of ENDO-treated fishes compared with PHE-treated fishes. Using RT-qPCR technique, CYP1A gene expression significantly up-regulated in all combinations, whereas CYP3A was unchanged, suggesting that enzymes involved in defense may play different roles in the detoxification. CYP7A1 gene responsible for bile acid biosynthesis is dramatically down-regulated after exposure to the synergistic combination exposure, referring that the synergistic effect may be resulted from the reduction of bile production in zebrafishes. Among gender-related genes, CYP11A1 and CYP17A1 genes in female zebrafish decreased after treatment with ENDO alone and combination of LC₅₀-ENDO and LC₁₀-PHE. This might be related to a reduction in cortisol production. The overall results indicated that ENDO and PHE were toxic to zebrafish adults both individually and in combination, and that their co-presence induced changes in the expression of genes responsible for metabolic processes and defense mechanisms.

Endocrine disruption of phenanthrene in the protogynous dusky grouper Epinephelus marginatus (Serranidae: Perciformes)

The dusky grouper Epinephelus marginatus is a protogynous hermaphrodite fish, that maintains high levels of plasma steroids as juveniles, as substrates for sex inversion. These fish are exposed to marine pollution from oil spills during cargo handling. Polycyclic aromatic hydrocarbons (PAHs), such as phenanthrene (Phe), are the main crude oil components and are toxic to fish, acting as endocrine disruptors (ED). This is the first study that investigated impacts of Phe as an ED in E. marginatus juveniles. An in vivo sublethal exposure (96h) to Phe was carried out at two concentrations (0.1mg/L and 1mg/L); exposure to the vehicle (ethanol; ETOH) was also performed. Plasma levels of 17β-estradiol (E₂), testosterone (T) and 11-ketotestosterone (11-KT) were measured by ELISA. Gonads, liver and spleen were processed for histological analysis. In an in vitro bioassay, gonad fragments were incubated with Phe (8.91mg/L) or ETOH. Steroid levels in the culture media were measured by ELISA. The in vivo exposure to Phe triggered an increase of the area of the hepatocytes, increased number of melanomacrophagic centers and hemosiderosis in the spleen; ETOH induced similar effects on spleen. E₂ and T levels did not change in plasma or in vitro media. In plasma, ETOH decreased 11-KT levels. Phenanthrene sharply reduced 11-KT levels in vitro. Although in vivo bioassay results were not unequivocal owing to ethanol effects, Phe might disrupt steroidogenesis in juvenile grouper, possibly causing dysfunctions during sex change and gonadal maturity, considering the importance of 11-KT in developing ovaries.

Phenanthrene-Induced Apoptosis and Its Underlying Mechanism

Phenanthrene (Phe) is one of the most abundant low-molecular-weight polycyclic aromatic hydrocarbons (PAHs). Widespread human and aquatic organism exposure to Phe has been reported, but the toxic effects of Phe and potential mechanisms are unclear. We focused on the chronic hepatotoxicity of Phe in adult Chinese rare minnows (Gobiocypris rarus) and the underlying mechanisms. The chronic effects of exposing Chinese rare minnows to 8.9, 82.3, or 510.0 μg/L Phe for 30 days were examined by histopathological observation, TUNEL assays, caspase activity assays, and gene expression profiles. The liver lesion frequency and hepatocyte apoptosis were increased in Phe-exposed groups. Caspase 9 and caspase 3 enzyme activity in liver tissues was markedly increased. The expression of miR-17/92 cluster members was significantly increased in the 82.3 and 510.0 μg/L groups. Moreover, the response of primary hepatocytes indicated a significant decrease in the mitochondrial membrane potential (MMP) after a 48 h exposure to Phe. Interestingly, miR-18a was significantly decreased in primary hepatocytes in all treatments. Moreover, molecular docking indicated that Phe might have the same binding domain as pri-miR-18a, forming pi-pi and pi-σ interactions with heterogeneous nuclear ribonucleoprotein (hnRNP) A1. Given the above, Phe caused liver lesions and induced hepatocyte apoptosis through the intrinsic apoptosis pathway, and the interaction of Phe with hnRNP A1 contributes to the suppression of miR-18a expression and hepatocyte apoptosis.

Comparing the effects of different dietary organic acids on the growth, intestinal short-chain fatty acids, and liver histopathology of red hybrid tilapia (Oreochromis sp.) and potential use of these as preservatives

Dietary organic acids are increasingly being investigated as a potential means of improving growth and nutrient utilization in aquatic animals. A 9-week study was performed to compare equal amounts (2%) of different organic acids (sodium butyrate, acetate, propionate, or formate) on the growth, muscle proximate composition, fatty acid composition, cholesterol and lipid peroxidation, differential cell counts, plasma biochemistry, intestinal short-chain fatty acid (SCFA) level, and liver histopathology to red hybrid tilapia (Oreochromis sp.) (initial mean weight of 2.87 g). A second experiment was performed to determine their effects on lipid peroxidation and trimethylamine (TMA) when added at 1% to tilapia meat and left out for 24 h. The results of the first experiment showed no treatment effect to growth, feeding efficiencies, or muscle fatty acid composition, but all dietary organic acids significantly decreased intestinal SCFA. Dietary butyrate and propionate significantly decreased muscle lipid peroxidation compared to the control group, but the dietary formate treatment had the lowest lipid peroxidation compared to all treatments. Muscle crude protein and lipid in tilapia fed the formate diet were significantly lower and higher, respectively, and showed evidence of stress based on the differential cell counts, significantly higher plasma glucose and liver glycogen, as well as inflammatory responses in the liver. Although a potential benefit of dietary organic acids was a reduction to lipid peroxidation, this could be accomplished post-harvest by direct additions to the meat. In addition, inclusions of butyrate and propionate to tilapia meat significantly decreased TMA, which might be a more cost-effective option to improve the shelf life of tilapia products.

A comparison of biomarker responses in juvenile diploid and triploid African catfish, Clarias gariepinus, exposed to the pesticide butachlor

Influence of waterborne butachlor (BUC), a commonly used pesticide, on morphometric, biochemical, and molecular biomarkers was evaluated in juvenile, full sibling, diploid and triploid African catfish (Clarias gariepinus). Fish were exposed for 21 days to one of three concentrations of BUC [mean measured µg/L: 22, 44 or 60]. Unexposed (control) triploids were heavier and longer and had higher visceral-somatic index (VSI) than diploids. Also, they had lighter liver weight (HSI) and showed lower transcript levels of brain gonadotropin-releasing hormone (GnRH), aromatase (cyp191b) and fushi tarazu-factor (ftz-f1), and plasma testosterone levels than diploids. Butachlor treatments had no effects, in either diploid or triploid fish, on VSI, HSI, weight or length changes, condition factor (CF), levels of plasma testosterone, 17-β estradiol (E2), cortisol, cholesterol, or mRNA levels of brain tryptophan hydroxylase (tph2), forkhead box L2 (foxl2), and 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2). Expressions of cyp191b and ftz-f1 in triploids were upregulated by the two highest concentrations of BUC. In diploid fish, however, exposures to all BUC concentrations decreased GnRH transcription and the medium BUC concentration decreased ftz-f1 transcription. Substantial differences between ploidies in basal biomarker responses are consistent with the reported impaired reproductive axis in triploid C. gariepinus. Furthermore, the present study showed the low impact of short term exposure to BUC on reproductive axis in C. gariepinus.

Virgin microplastics cause toxicity and modulate the impacts of phenanthrene on biomarker responses in African catfish (Clarias gariepinus)

Despite the ubiquity of microplastics (MPs) in aquatic environments and their proven ability to carry a wide variety of chemicals, very little is known about the impacts of virgin or contaminant-loaded MPs on organisms. The primary aim of this study was to investigate the impacts of virgin or phenanthrene (Phe)-loaded low-density polyethylene (LDPE) fragments on a suite of biomarker responses in juvenile African catfish (Clarias gariepinus). Virgin LDPE (50 or 500µg/L) were preloaded with one of two nominal Phe concentrations (10 or 100µg/L) and were exposed to the fish for 96h. Our findings showed one or both Phe treatments significantly increased the degree of tissue change (DTC) in the liver while decreased the transcription levels of forkhead box L2 (foxl2) and tryptophan hydroxylase2 (tph2) in the brain of C. gariepinus. Exposure to either levels of virgin MPs increased the DTC in the liver and plasma albumin: globulin ratio while decreased the transcription levels of tph2. Moreover, MPs modulated (interacted with) the impact of Phe on the DTC in the gill, plasma concentrations of cholesterol, high-density lipoprotein (HDL), total protein (TP), albumin, and globulin, and the transcription levels of fushi tarazu-factor 1 (ftz-f1), gonadotropin-releasing hormone (GnRH), 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2), and liver glycogen stores. Results of this study highlight the ability of virgin LDPE fragments to cause toxicity and to modulate the adverse impacts of Phe in C. gariepinus. Due to the wide distribution of MPs and other classes of contaminants in aquatic environments, further studies are urgently needed to elucidate the toxicity of virgin or contaminant-loaded MPs on organisms.

Trypsin-modulating oostatic factor (TMOF) decreased the survival, growth and digestion enzymes of Macrobrachium rosenbergii

Trypsin-modulating oostatic factor (TMOF) is an effective mosquito larvicide, but information on its potential toxicity to non-target organisms is limited. To investigate this, triplicate groups of 10 Macrobrachium rosenbergii were exposed to 0, 10, 50 or 100 mg/L nominal TMOF concentrations for 12 days. Tail moisture, crude protein, and hepatopancreatic glycogen/histopathology were unaffected, but increasing TMOF linearly decreased survival and growth. TMOF at the lowest concentration employed significantly decreased trypsin and chymotrypsin activities.

Alterations in juvenile diploid and triploid African catfish skin gelatin yield and amino acid composition: Effects of chlorpyrifos and butachlor exposures

Skin is a major by-product of the fisheries and aquaculture industries and is a valuable source of gelatin. This study examined the effect of triploidization on gelatin yield and proximate composition of the skin of African catfish (Clarias gariepinus). We further investigated the effects of two commonly used pesticides, chlorpyrifos (CPF) and butachlor (BUC), on the skin gelatin yield and amino acid composition in juvenile full-sibling diploid and triploid African catfish. In two separate experiments, diploid and triploid C. gariepinus were exposed for 21 days to graded CPF [mean measured: 10, 16, or 31 μg/L] or BUC concentrations [Mean measured: 22, 44, or 60 μg/L]. No differences in skin gelatin yield, amino acid or proximate compositions were observed between diploid and triploid control groups. None of the pesticide treatments affected the measured parameters in diploid fish. In triploids, however, gelatin yield was affected by CPF treatments while amino acid composition remained unchanged. Butachlor treatments did not alter any of the measured variables in triploid fish. To our knowledge, this study is the first to investigate changes in the skin gelatin yield and amino acid composition in any animal as a response to polyploidization and/or contaminant exposure.

Diploid and triploid African catfish (Clarias gariepinus) differ in biomarker responses to the pesticide chlorpyrifos

The impacts of environmental stressors on polyploid organisms are largely unknown. This study investigated changes in morphometric, molecular, and biochemical parameters in full-sibling diploid and triploid African catfish (Clarias gariepinus) in response to chlorpyrifos (CPF) exposures. Juvenile fish were exposed to three concentrations of CPF (mean measured μg/L (SD): 9.71 (2.27), 15.7 (3.69), 31.21 (5.04)) under a static-renewal condition for 21days. Diploid control groups had higher hepatosomatic index (HSI), plasma testosterone (T), and brain GnRH and cyp19a2 expression levels than triploids. In CPF-exposed groups, changes in HSI, total weight and length were different between the diploid and triploid fish. In contrast, condition factor did not alter in any of the treatments, while visceral-somatic index (VSI) changed only in diploids. In diploid fish, exposure to CPF did not change brain 11β-hsd2, ftz-f1, foxl2, GnRH or cyp19a2 mRNA levels, while reduced tph2 transcript levels compared to the control group. In contrast, 11β-hsd2 and foxl2 expression levels were changed in triploids following CPF exposures. In diploids, plasma T levels showed a linear dose-response reduction across CPF treatments correlating with liver weight and plasma total cholesterol concentrations. In contrast, no changes in plasma cholesterol and T concentrations were observed in triploids. Plasma cortisol and 17-β estradiol (E2) showed no response to CPF exposure in either ploidy. Results of this first comparison of biomarker responses to pesticide exposure in diploid and polyploid animals showed substantial differences between diploid and triploid C. gariepinus.