Liver Of Catfish Research Articles

New insights into ER stress mediated by ATF6 and IRE1-XBP1 signals in yellow catfish under hypoxia

In aquaculture, fish are often exposed to the major stressor of hypoxia. However, the mechanism of hypoxia-induced stress remains unclear. The present study aimed to investigate the physiological and molecular responses of yellow catfish (Pelteobagrus fulvidraco) to hypoxia stress and to further elucidate its stress response mechanisms. Each fish (28.14 ± 0.75 g) in the hypoxia group was individually placed in a 1 L transparent plastic tank and transferred to a closed hypoxia environment, where the oxygen and carbon dioxide levels were adjusted to 2 % and 0.5 %, respectively. The results showed that hypoxia stress induced a stress response in yellow catfish, characterized by significant changes in lactate dehydrogenase (LD) and cortisol levels in plasma and liver, as well as increased apoptosis of brain cells and liver damage. Additionally, the HPA axis was activated, playing a crucial role in stress regulation during hypoxia exposure. And under hypoxia conditions, endoplasmic reticulum (ER) stress pathways were activated in yellow catfish liver, specifically showing significant upregulation of the activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1 (IRE1)-X-box binding protein 1 (XBP1) signals, while the activated transcription factor 4 (ATF4) pathway remained inactive. The expression levels of atf6, ire1 and xbp1 genes, as well as ATF6, IRE1 and XBP1 proteins in the ATF6 and IRE1-XBP1 pathways, were significantly elevated. However, there was no significant differences in the expression levels of protein kinase R-like ER kinase (perk), eukaryotic translation initiation factor 2α (eif2α) and atf4 key genes, as well as PERK, EIF2α and ATF4 proteins in the PERK-ATF4 pathway. It is concluded for the first time that hypoxia significantly activates ER stress through the ATF6 and IRE1-XBP1 signaling pathways, but not the PERK-ATF4 pathway in yellow catfish. These findings not only provide new insights into the stress response mechanisms of fish but also offer the accurate molecular target of hypoxia-induced stress for aquaculture management.

Histopathology of Liver, Kidney, Intestine, Spleen, and Bile of Catfish with Jaundice

Jaundice is a disease that can affect catfish, resulting in low or unsalable selling prices. The yellow colour in catfish is associated with tissue/organ disorders, particularly bile or liver function. This study aims to compare the histopathological structure of the liver, kidney, intestine, spleen, and bile of naturally jaundiced catfish and those injected with bacteria associated with jaundice. The study employed the observation method, using three variables: healthy catfish as a control (K), yellow catfish treated with Aeromonas spp. bacteria associated with jaundice (KP), and yellow catfish from the farm (KL). The results of the observation showed that the field scale variable (KL) had a higher level of necrosis damage in each organ compared to the laboratory scale variable (KP). The yellow colour in catfish is caused by disrupted organ tissue, particularly in the bile or liver. This can be observed in the liver, intestines, kidneys, spleen, and bile, where the field variable consistently indicates high levels of necrosis damage, with scores ranging from 1.11 to 2.48. Some of these scores indicate moderate damage, with a necrosis percentage of 40% ≤ P < 60% in the liver, kidneys, and bile organs. Keyword: Clarias sp., histopathology, jaundice, necrosis ABSTRAK Salah satu penyakit yang menyerang ikan lele adalah penyakit kuning atau dikenal juga dengan jaundice, yang dapat mengakibatkan harga jual menjadi rendah atau bahkan tidak dapat dijual. Warna kuning pada ikan lele dikaitkan dengan gangguan jaringan / organ, terutama empedu atau fungsi hati. Penelitian ini bertujuan untuk membandingkan struktur histopatologi organ hati, ginjal, usus, limpa, dan empedu ikan lele yang sakit kuning baik yang alami maupun yang diinjeksi dengan bakteri yang berasosiasi dengan penyakit kuning. Penelitian ini menggunakan metode observasi dengan tiga variabel yaitu ikan lele sehat sebagai kontrol (K), ikan lele kuning yang diberi perlakuan injeksi dengan bakteri yang berasosiasi dengan penyakit kuning yaiatu bakteri Aeromonas spp. (KP), dan ikan lele kuning yang berasal dari farm (KL). Hasil pengamatan yang diperoleh menunjukkan bahwa variabel skala lapangan (KL) memiliki tingkat kerusakan nekrosis paling tinggi pada setiap organnya dibandingkan dengan variabel skala laboratorium (KP). Warna kuning pada ikan lele berhubungan dengan terganggunya jaringan organ terutama empedu atau fungsi hati. Terlihat pada organ hati, usus, ginjal, limpa, dan empedu bahwa variabel lapangan selalu mendapatkan skor tingkat kerusakan nekrosis yang tinggi dengan kisaran nilai skoring 1,11-2,48 yang sebagian tergolong kerusakan sedang dengan persentase nekrosis 40% ≤ P<60% pada organ hati, ginjal, dan empedu. Kata kunci: Clarias sp., histopatologi, nekrosis, penyakit kuning

Dietary betulinic acid alleviates high carbohydrate diet-induced hepatic de novo lipogenesis through AMPK signaling and improves liver health in channel catfish (Ictalurus punctatus)

A high carbohydrate diet (HCD) induced excessive hepatic de novo lipogenesis, which caused metabolic disorder and impaired the health of fish species. Betulinic acid (BA) has been applied to ameliorate fatty liver and anti-inflammatory in mammals. Here, we investigated the effects of dietary BA supplementation on HCD-induced hepatic de novo lipogenesis and liver health in channel catfish (Ictalurus punctatus). The catfish were fed with three diets: NCD (18 % carbohydrate), HCD (36 % carbohydrate), HCD+BA (36 % carbohydrate with 150 mg/kg BA). After an 8-week feeding trial, we found that dietary BA decreased hepatosomatic index (HSI) and condition factor (CF) without affecting the growth of channel catfish fed HCD. Dietary BA significantly reduced the HCD-induced excessive lipid accumulation (oil red O area, TG content, and de novo lipogenesis gene expression, P < 0.05). Moreover, we found that dietary BA prevented hepatic lipid accumulation via activating phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and inhibiting sterol regulatory element-binding protein 1 (SREBP1) (P < 0.05) in liver of channel catfish fed HCD. Besides, we also found that dietary BA significantly prevented HCD-induced liver damage, as confirmed by liver H&E staining, reduced inflammation biomarkers (ALT, AST, hydroxyproline, α-sma and tgf-1β), downregulated expression of ER stress-related genes (eif2a, bip, atf4, xbp1) (P < 0.05). Overall, the present study indicated that dietary BA inclusion attenuated hepatic de novo lipogenesis, improved liver inflammation and reduced ER stress in channel catfish fed HCD.

Replacement of fishmeal by fermented spent coffee ground: Effects on growth performance, feed stability, blood biochemistry, liver, and intestinal morphology of African catfish (Clarias gariepinus)

There has been a consistent interest in the aquaculture industry in the use of plant elements as a substitute for fish meal (FM). The present study aimed to examine the impact of substituting FM with varying proportions of fermented spent coffee grounds (FCG) on the growth performance, feed stability, blood biochemistry, liver, and intestinal histology of African catfish, Clarias gariepinus. Five isonitrogenous diets were formulated with a crude protein content of 32 %. These diets were created with different percentages of FM replacement, specifically 0 % (T1), 10 % (T2), 20 % (T3), 40 % (T4), and 80 % (T5). The fish were then fed these diets for a duration of 70 days. The results showed that fish provided with 10 % FCG (T2) gave the highest improvement (p < 0.05) in growth conditions compared with other treatments. The feed’s physical properties were varying, but floatability and water stability were highest in T2 diets. Total bacteria (TB) in feed and intestine were more elevated in fish fed with 10 % FCG compared to other treatments. The histopathological damage in the intestine and liver morphology was observed when the level of inclusion of FCG was increased in all treatments. In addition, T2 gave the highest value (p < 0.05) in villus length, width, and crypt depth. Some parameters were improved in both blood haematology and blood biochemical parameters, and T2 gave the highest value (p < 0.05) in white blood cells, lymphocytosis, monocytes, red blood cells, haemoglobin, albumin, globulin, total protein, and creatine. In summary, the substitution of 10 % FCG with FM holds potential for application within the aquafeed sector, as it has been observed to contribute to enhanced growth and improved health conditions in African catfish and other freshwater species.

Diets including l-carnitine and varying oil sources regulate liver and testes fatty acids profile and interfere with sperm production in silver catfish (Rhamdia quelen)

This study aimed to evaluate seminal and sperm production, growth, health, and lipid metabolism of male silver catfish (Rhamdia quelen) fed diets containing l-carnitine and varying lipid sources. Herein, males and females (167.33 ± 9.24 g) were both fed across 223 d with eight (08) isoproteic (282 g of digestible protein kg of ration −1) and isoenergetic (13.34 MJ of digestible energy kg of ration −1) diets, containing 0.00, 0.15, 0.45, and 0.75 g l-carnitine kg −1 of feed, soybean, and marine fish oils. Feeding males with diets containing l-carnitine and different oils resulted in an interactive effect (p < 0.05) that improved sperm production. Furthermore, males fed soybean oil and 0.45 g l-carnitine kg −1 had the highest seminal pH and sperm velocities. Fish fed fish oil and 0.75 g l-carnitine kg−1 had the highest gonadosomatic indexes, sperm production, and superoxide dismutase activities recorded in the testes. The testes of these fish also showed increases in docosahexaenoic acid (DHA), polyunsaturated fatty acids (PUFAs), n-3 fatty acids, and higher n-3: n-6 ratios. The individual effect of oils produced viscera with more (p < 0.05) fat, in addition to having higher (p < 0.05) blood levels of albumin, total cholesterol, triglycerides, alongside the lowest level of aspartate aminotransferase in fish fed marine fish oil. The individual effect of l-carnitine also produced muscles with less (p < 0.05) fat, in addition to the highest (p < 0.05) amount of total cholesterol with the lowest amount of high-density lipoprotein (HDL) cholesterol in the blood of fish fed with 0.75 g l-carnitine kg−1. l-carnitine and oils in the diets promoted hepatic and testicular protection whilst regulating lipid metabolism and fatty acid profile in the liver and testes of silver catfish (Rhamdia quelen) males. These benefits led to greater sperm production when fish oil and 0.75 g kg −1 were used, and faster spermatozoa with soybean oil and 0.45 g kg −1.

Variations of Lipids in Different Tissues (Liver, Intestine and Brain) of Fresh Water Cat Fish [Heteropneustes fossils (Bloch)

In the present study on characterization and identification of lipids by thin layer chromatography in different tissues of Heteropneustes fossilis showed a considerable variation. The number of lipid spots was highest in brain compared to other tissues. The Rf values of spots indicate the regions of similarity between tissues. Comparison of Rf values with those of standards indicated that the presence of phospholipids, choline lipids, gyolopids, ninhydrine, amino group containing lipids were present. Intestine showed more amount of glycolipids and low amount of ninhydrine containing lipids, While liver possessed Iodine containing lipids.in addition these, whereas brain showed glycolipids, ninhydrine containing lipids, Iodine containing lipids and choline lipids too. The present study revealed that the Brain contain highest amount of different classes of lipids. The Liver tissue has shown less number of lipids. Glycolipids and general class of lipids are present in all tissues with minor variations, choline lipids present in brain but not in remaining tissues, while Phospho lipids are present in intestine and brain only, whereas amino group containing lipids were more in all tissues when compared with other class of lipids.

Transcriptomic Association Analysis of the Metabolic Mechanism of Sulfamethoxazole in Channel Catfish (Ictalurus punctatus).

Sulfamethoxazole is a widely used antimicrobial drug used to treat bacterial diseases in aquaculture. To understand the gene expression in channel catfish liver after treatment with sulfamethoxazole, in this study, the treatment group received sulfamethoxazole (100 mg/kg bw), which was administered orally once, and samples were taken at 5 h, 12 h, and 6 d after the administration of sulfamethoxazole, while the control group was orally administered sterile water. To further identify potentially significant genes, a transcriptome analysis using RNA-seq was carried out. More than 50 million high-quality reads were found. After filtering and quality analysis, these reads were identified as 54,169,682, 51,313,865, 51,608,845, and 49,333,491. After counting 23,707 of these transcripts for gene expression, it was discovered that 14,732 of them had genes with differential expression. Moreover, we found that the annotation with the most GO variation was "cellular process" (1616 genes), "metabolic process" (1268 genes), "binding" (1889 genes), and "catalytic activity" (1129 genes). KEGG pathways showed that the "metabolic pathway" was the pathway that was significantly enriched in both experimental groups when comparing the experimental groups: 5 h and 12 h (128 genes); 5 h and 6 d (332 genes); and 12 h and 6 d (348 genes). Also, UDP- glucuronosyltransferase (ugt), which is associated with glucuronidation, and UDP-glucuronosyltransferase 2C1-like (ugt2a1) showed significant upregulation. Carboxylesterase 5A-like (ces3), which promotes fatty acyl and cholesteryl ester metabolism, and the glutathione transferase family were upregulated in the expression of sulfamethoxazole metabolism in the liver, which significantly affected the metabolic effects of the drug. Meanwhile, dypd, uck2b, and rrm2, which are related to nucleotide synthesis and metabolism, were upregulated. Our study extends the knowledge of gene expression in drug metabolism in channel catfish and further provides insight into the molecular mechanism of sulfamethoxazole metabolism.

Insight Into Dietary Utilization of African Palm Weevil (Rhynchophorus phoenicis) Oil: Assessing the Effect on Growth, Serum Biochemistry, Liver, and Intestinal Histomorphology of African Catfish (Clarias gariepinus)

The quest to reduce dependency on fish‐ or vegetable‐based oil resources has prompted aquaculture experts to intensify their search for a suitable and sustainable alternative for aquafeed production. Based on this reality, the current study was designed to evaluate the dietary influence of African palm weevil oil (PWO) on the growth performance, serum biochemistry, lipid peroxidation products, antioxidant enzyme response, and organ integrity of African catfish (Clarias gariepinus) juveniles. Four diets were formulated, wherein the control diet was prepared using soybean oil (SO) as the main dietary oil source and was replaced with PWO in the treatment diets at 50% (PWO‐50), 75% (PWO‐75), or 100% (PWO‐100). A total of 180 African catfish (average weight: 18.76 ± 0.043) were randomly stocked at 15 fish per 50‐L tank in triplicate and hand‐fed to apparent satiation twice daily for 45 days. The results showed that the highest weight gain (WG), specific growth rate (SGR), and thermal growth coefficient (TGC) were found in control (SO)‐fed fish, which is similar to the PWO 50% but differs significantly from others (p &lt; 0.05). The feed conversion ratio (FCR) and protein productive value (PPV) showed linear and quadratic trends, with a significantly lowest and highest value recorded in fish‐fed control and PWO 50%, respectively, compared to other dietary groups (p &lt; 0.05). The protein efficiency ratio (PER) value decreases linearly (p &lt; 0.001) as the level of PWO increases. The highest total immunoglobulin (TIG) and superoxide dismutase (SOD) activity were recorded in fish fed PWO‐50%, while PWO‐75% registered the highest lysozyme activity (LA). There was no statistically significant difference (p &gt; 0.05) in the physiological parameters such as total cholesterol (TC), triglyceride (TG), low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol (HDL‐C), alanine aminotransferase (ALT), C‐reactive protein (CRP), and lipid peroxidation index (malondialdehyde [MDA]) among the groups. The fish fed PWO‐100% had the lowest recorded values of villus height, area of absorption, and cryptal depth (p &lt; 0.05). In summary, the current finding shows that oil extracted from African palm weevils appears promising at a 50% dietary level without impairing the growth performance, liver, or intestinal health of African catfish.

The SLC38A9–mTOR axis is involved in autophagy in the juvenile yellow catfish (Pelteobagrus fulvidraco) under ammonia stress

The primary objective of this study was to examine the effect of acute ammonia stress on hepatic physiological alterations in yellow catfish by performing a comprehensive analysis of the metabolome and transcriptome. The present study showed that ammonia stress led to liver metabolic disruption, functional incapacitation, and oxidative damage. Transcriptomic and metabolomic analyses revealed transcriptional and metabolic differences in the liver of yellow catfish under control and high ammonia stress conditions. After 96 h of acute exposure to ammonia, the mRNA levels of 596 liver genes were upregulated, whereas those of 603 genes were downregulated. Enrichment analysis of the differentially expressed genes identified multiple signalling pathways associated with autophagy, including the endocytosis, autophagy-animal, and mammalian target of rapamycin signalling pathways. A total of 186 upregulated and 117 downregulated metabolites, primarily associated with amino acid biosynthesis pathways, were identified. Multi-omics integration revealed the solute carrier family 38 member 9 (SLC38A9)-mammalian target of rapamycin axis as a signalling nexus for amino acid-mediated modulation of autophagy flux, and q-PCR was used to assess the expression of autophagy-related genes (LC3a and sqstm1), revealing an initial inhibition followed by the restoration of autophagic flux during ammonia stress. Subsequent utilisation of arginine as a specific SLC38A9 activator during ammonia stress demonstrated that augmented SLC38A9 expression hindered autophagy, exacerbated ammonia toxicity, and caused a physiological decline (total cholesterol, total triglyceride, acid phosphatase, alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase levels were significantly increased), oxidative stress, and apoptosis. Autophagy activation may be an adaptive mechanism to resist ammonia stress.

Identification of genes related to growth from transcriptome profiles of the muscle and liver of Chinese longsnout catfish (Leiocassis longirostris)

The Chinese longsnout catfish (Leiocassis longirostris) is a commercially important freshwater fish species in China. To understand the molecular mechanisms underlying its growth, we performed a comparative transcriptomic analysis of muscle and liver tissues of fast- and slow-growing L. longirostris. A total of 580 and 511 differentially expressed genes (DEGs) were obtained in the muscle and liver tissues, respectively. We selected 10 DEGs each from muscle and liver tissues by qRT-PCR to verify the reliability of RNA-seq, and it was found that the expression patterns of these genes were consistent with RNA-seq analysis results. According to the differential expression and functional enrichment analysis of genes, we found differences in the expression of several growth-related genes between fast- and slow-growing individuals. These genes may contribute to the differences in the growth of L. longirostris by influencing muscle growth and the metabolism of substances and energy. In particular, the pk and fabp genes were highly expressed in fast-growing individuals, while the cart, leptin, pepck, murf1, trim32, and pparα genes exhibited higher levels in slow-growing individuals. It was speculated that genes related to feeding behavior might be the key genes in regulating the growth of L. longirostris, while glycolytic/gluconeogenic metabolic pathway, lipid metabolism, and ubiquitin-proteasome pathway might be the main pathways involved in regulating body weight of L. longirostris. This study could enrich the available gene resources and provide a valuable basis for further studies on the regulatory mechanisms of growth in L. longirostris.

Comparative transcriptomic analyses of brain-liver-muscle in channel catfish (Ictalurus punctatus) with differential growth rate

Growth is an important economically trait for aquatic animals. The popularity of farmed channel catfish (Ictalurus punctatus) in China has recently surged, prompting a need for research into the genetic mechanisms that drive growth and development to expedite the selection of fast-growing variants. In this study, the brain, liver and muscle transcriptomes of channel catfish between fast-growing and slow-growing groups were analyzed using RNA-Seq. Totally, 63, 110 and 86 differentially expressed genes (DEGs) were from brain, liver and muscle tissues. DEGs are primarily involved in growth, development, metabolism and immunity, which are related to the growth regulation of channel catfish, such as growth hormone receptor b (ghrb), fibroblast growth factor receptor 4 (fgfr4), bone morphogenetic protein 1a (bmp1a), insulin-like growth factor 2a (igf2a), collagen, type I, alpha 1a (col1a1a), acyl-CoA synthetase long chain family member 2 (acsl2) and caveolin 1 (cav1). This study advances our knowledge of the genetic mechanisms accounting for differences in growth rate and offers crucial gene resources for future growth-related molecular breeding programs in channel catfish.

Influence of stocking density and environmental factors on the expression of insulin-like growth factors in cage-reared butter catfish (Ompok bimaculatus, Bloch 1794) within a large reservoir ecosystem.

In vertebrates, insulin-like growth like factors (IGFs) play an important role in growth and other physiological processes. The GH-IGF axis is considered a valuable tool to monitor fish growth performance. Herein, we report the molecular characterization of igf-1, igf-2, and β-actin transcripts and relative expression of igf-1 and igf-2 in the liver and muscle tissue of cage-reared butter catfish, Ompok bimaculatus, in response to different stocking densities (T1, 15 fingerlings m-3; T2, 25 fingerlings m-3; and T3, 35 fingerlings m-3) over 180days of culture duration. The length of the partial amplified transcript sequence of Obigf-1, Obigf-2, and Obβ-actin was 325, 438, and 924bp, respectively. Phylogenetically, Obigf-1 and Obigf-2 were closely clustered with catfishes, viz., Clarias magur, Bagarius yarrelli, and Silurus asotus. The expression of igf-1 was significantly downregulated in the liver at higher densities after 120days as biomass in the cages increased, while igf-2 expression did not change with the stocking densities over the culture period. Cortisol concentration was significantly elevated in T3 groups post 150days of the culture period and correlated negatively with the expression of igf-1 (p < 0.05) and igf-2 (p > 0.05). Environmental parameters, pH, TDS, hardness, conductivity, and alkalinity showed a significant positive correlation with hepatic IGF expression. Our study indicates that the liver-derived igf-1 plays a more important role in the regulation of growth in response to culture density in the species studied, and thus, igf-1 can be used effectively as a biomarker for growth. Furthermore, this study will help in planning a proper harvest schedule and optimize the culture practices of O. bimaculatus in an open water cage system.

Effects of acute hypoxic post-feeding condition on respiratory metabolism and digestion in yellow catfish (Pelteobagrus fulvidraco)

In this study, acute hypoxia was applied to two states of yellow catfish (Pelteobagrus fulvidraco) (non-feeding and feeding) for 48 h. We investigated the effects of acute hypoxia on the respiratory metabolism and digestive ability of yellow catfish (mean body length: 7.61 ± 0.52 cm). The results indicated that the respiratory frequency of yellow catfish under acute hypoxic post-feeding condition was rapidly accelerated and the oxygen consumption rate was reduced. The level of succinate dehydrogenase in the gills first increased and then significantly decreased (p < 0.05) and the level of lactate dehydrogenase significantly increased (p < 0.05). When the expression level of hypoxia-inducing factor was significantly increased (p < 0.05), the downstream coding genes (hexokinase 1 (hk1), phosphofructokinase (pfkla), and pyruvate kinase M1/2a (pkma)), key molecules of glycolysis, and the activity of crucial enzymes (hexokinase, phosphofructokinase, and pyruvate kinase) increased. At the same time, the glucose level dropped and the lactic acid level increased, indicating that the metabolic mode in the gills of yellow catfish under acute hypoxic post-feeding condition gradually changed to anaerobic, and the anaerobic glycolysis process was activated to provide the required energy for the body. In addition, we found that the activity of digestive enzymes (trypsin, lipase, and amylase) and expression levels of digestive genes (trypsin, lipase, and amylase) were inhibited in the liver and intestine of yellow catfish under the acute hypoxic post-feeding condition, indicating that their digestive ability was reduced. This may adversely affect growth and development. This study analyzed the effects of acute hypoxic post-feeding exposure on the respiratory metabolism and digestive capacity of yellow catfish, providing new insights into fish physiology and sustainable fish culture.

Heavy metal concentration in blood and selected tissues of cat fish from Kwalkwalawa River, Sokoto

Fish is a cheap source of omega- 3 polyunsaturated fatty acids for humans. However, the presence of toxic heavy metals in water can be detrimental to both fish and humans. The aim of this study was to investigate the levels of heavy metals in the liver, kidney and gills of cat fish obtained from Kwalkwalawa River, Sokoto. Water, sediments, blood and tissue samples of (10) cat fish (Clarias gariepinus) species caught from Kwalkwalawa river were analysed quantitatively for the presence of zinc, copper, lead, chromium and cadmium using atomic absorption spectrophotometer. Bioaccumulation of these heavy metals was estimated in these organs. Results showed that lead concentrations in the water was significantly higher (p &lt; 0.05) compared to the sediment sample. Also, copper and lead accumulated most in the liver and kidney when compared with that observed for the gills. In conclusion, lead and cadmium levels in the samples were above WHO certified limits hence the concentration of metals in this water should be monitored periodically.

From watersheds to dinner plates: Evaluating PFAS exposure through fish consumption in Southeast Michigan

Muscle tissue and organ samples of six different fish species were collected from ten locations in Southeast Michigan's Huron and Rouge watersheds. Per- and polyfluoroalkyl substances (PFAS) were analyzed in 36 samples comprising filets, liver, gut, and eggs using targeted analysis and the direct total oxidizable precursor (dTOP) assay on a subset of six samples. The median concentrations of the ∑PFAS in filets from the Huron and Rouge watersheds were 13 and 6.3 ng/g wet weight (w.w.), respectively. Perfluorooctane sulfonate (PFOS) was the most detected and abundant compound in fish organs, with the liver having the largest overall burden of PFAS. The highest percent increase in targeted PFAS after the dTOP assay was observed in the Catfish filet (552%) while the smallest increase was in the Catfish liver (32%) accounting for 1.3 and 8.1 nMole F/g dry weight (d.w.), respectively. The positive matrix factorization (PMF) analysis revealed three distinct PFAS sources, of which the one attributed to PFOS explained 73% of the data. Results from this work have important implications for fish consumption in Michigan waterways. Among the filet samples analyzed, the calculated daily consumption limit of total PFOS was exceeded in approximately 82% and 91% of samples for adults and children over the age of seven years old, respectively.

Oxidative stress responses to heavy metal burden in African catfish (&lt;i&gt;Clarias gariepinus&lt;/i&gt;) from Warri River, Niger-Delta, Southern Nigeria

Despite the degradation and threat of ubiquitous contaminants, such as heavy metals, in Warri River, Southern Nigeria, little is known about the ecological effects of such pollution using pro-oxidant variables. This study investigated oxidative stress responses to heavy metals (lead (Pb), cadmium (Cd), manganese (Mn), nickel (Ni) and copper (Cu)) burden in the heart, kidney, liver and gills of African catfish inhabiting Warri River. Fish (N=30) were collected during August-September, 2018 from two contaminated sites along the course of Warri River and a fish farm which was considered a reference site. The concentrations of Pb, Cd and Ni in the two contaminated sites were above the WHO permissible limits and significantly higher (p&lt;0.05) as compared to the fish collected from the reference site. The trend of accumulation of the metals followed the order: Reference site (site 1)-Mn&gt;Ni&gt;Cu&gt;Pb&gt;Cd; site 2-Pb&gt;Cu&gt;Cd&gt;Mn&gt;Ni and site 3-Ni&gt;Mn&gt;Cu&gt;Cd and Pb respectively. The activities of catalase (CAT) and superoxide dismutase (SOD) were significantly higher (p&lt;0.05) in the organs of fish caught at the two contaminated sites. Malondialdehyde (MDA) was significantly elevated (p&lt;0.05), in the liver and heart of fish obtained from site 3, relative to sites 2 and 1. Fish obtained from the two contaminated sites had significantly decreased (p&lt;0.05) levels of reduced glutathione (GSH) in their organs, however, the reduction was more in site 2. The results of this study confirm that environmental stressors, such as heavy metals, can alter antioxidant enzymes and glutathione systems, as well as induce lipid peroxidation, leading to oxidative stress in aquatic organisms.

Effect of Raw Leachate on Gills and Liver of Juvenile African catfish (Clarias gariepinus)

Effect of Raw Leachate on Gills and Liver of Juvenile African catfish (Clarias gariepinus)

Histopathological Alterations in Gills, Liver and Kidney of African Catfish (Clarias gariepinus, Burchell 1822) Exposed to Melaleuca cajuputi Extract.

This study evaluated the histopathological changes in the gill, liver and kidney of African catfish (Clarias gariepinus) intoxicated with a sub-lethal dose of Melaleuca cajuputi leaves extract (MCLE) for 96 h. The acute toxicity test has been determined previously with a value of 96-h LC50 = 127 mg/L, hence the selection of sub-lethal ranges from 60 mg/L to 160 mg/L of MCLE. Degenerative alterations were prominent in all tested organs, particularly after exposure to a high concentration of MCLE. Gill exhibited haemorrhage, epithelial lifting, lamellar disorganisation, and necrosis after exposure to a high MCLE concentration. Alterations in the liver include congestion, hydropic degeneration, and vacuolation, whereas lesions in the kidney were pyknosis, vacuolation, hydropic degeneration, and tubular necrosis. The obtained data showed that the organs experienced severe changes proportional to the increase in MCLE concentration. In addition, fish exposed to higher concentrations than the LC50 value experienced irreversible lesions. The present study suggests that the use of MCLE below the LC50 is recommended to avoid severe alterations to organs, particularly in African catfish. This study demonstrated that the use of MCLE above the LC50 promotes severe damage to the gills, liver and kidney of African catfish. However, further investigations are needed to define the causing-mechanisms underlying these effects.

Complete genome sequence data of multidrug-resistant Aeromonas hydrophila Ah27 isolated from intussusception channel catfish (Ictalurus punctatus)

Aeromonas hydrophila Ah27, a multidrug-resistant bacterium, was separated from the liver of an intussusception channel catfish (Ictalurus punctatus) in Guizhou province, China. The genome of A. hydrophila Ah27 was sequenced using the PacBio RS and Illumina sequencing platforms. The complete genome of A. hydrophila Ah27 consists of a circular chromosome with 5,102,912 bp and a plasmid with 6162 bp. The chromosome's average GC content is 60.75 %. NCBI Prokaryotic Genome Annotation Pipeline (v1.02) was used to annotate the genome with the default parameters. The results showed that the chromosome contained 4726 coding genes, including 4505 protein coding sequences, 119 tRNA genes, 31 rRNA genes, 7 ncRNAs and 64 Pseudo Genes. According to the annotation analysis, strain Ah27 encodes β-lactams, aminoglycosides, quinolones, macrolides, sulfonamides, tetracyclines resistance genes, and four significant types of efflux pump genes. The Kirby-Bauer disk method was used to detect the sensitivity or resistance of Ah27. The results showed that strain Ah27 was resistant to 27 antibiotics, including spectinomycin, streptomycin, enrofloxacin, tetracycline, bacitracin, clarithromycin, erythromycin, trimethoprim, etc. At the same time, 30 mobile genetic elements were also obtained by comparison with the MobileElementFinder tool. The complete genome sequence of A. hydrophila Ah27 may also provide a fresh perspective on disease prevention and antimicrobial resistance mechanisms.

Effect of mercury on histological alterations in gill, liver and stomach tissues of Indian catfish, Clarias batrachus

Heavy metal pollution poses a great threat to aquatic ecosystem, ultimately threatening the survival of safe and healthy life on earth. Contaminated water persuades pathological alterations and behavioural changes in fish. Mercury is highly toxic and seriously affects aquatic organisms, ultimately affecting humans.The present study aimed to assess the histological alterations in tissues like gill, liver and stomach of Indian catfish Clarias batrachus. The fish were divided in to four groups i.e. one control (Group I) and three groups of different concentration of mercury chloride treated groups, i.e.0.0002mg/l (Group II), 0.002mg/l(Group III), and 0.02mg/l (Group IV) for 14 days. Each group contained 25 number of fish.The results indicated degenerative changes in gill, liver and stomach tissues of exposed fish. Level of changes were higher with respect to higher in concentration. Rupture of epithelial layer, club shaped gill filament, broken gill lamellae, hyperplasia of interlamellar epithelium, deletion of secondary lamellae, formation of vacuoles, blood conjugation and necrosis in gill filaments were observed in gill tissues of exposed fish. Liver damage included hepatocellular dissociation, inflamed hepatocytes, cloudy swelling, vacuole formation and hydropic degeneration. Besides, stomach tissues showed alterations such as thinner serosa, vacuolization, muscle damage, and necrosis at several points. The study confirmed that mercury is life hazardous even at very low concentration.