Effects of water pollution on the gill apparatus of fish

Functional characterization of a putative lipopolysaccharide-induced TNF-alpha factor (LITAF) from blood clam Tegillarca granosa in innate immunity

Lipopolysaccharide-induced TNF-alpha factor (LITAF), as a transcription factor, activates the transcription of TNF and other cytokines in inflammatory response upon lipopolysaccharide (LPS) stimulation. In the present study, we cloned and identified the full-length cDNA of LITAF homolog from blood clam Tegillarca granosa for the first time. The full-length cDNA of TgLITAF was 1801 bp encoding a polypeptide of 147 amino acids with an estimated molecular mass of 16.13 kDa. TgLITAF contained a zf-LITAF-like zinc ribbon domain at the C-terminal of the protein and the TgLITAF domain showed 48-74% amino acid sequence identity with other known LITAFs from other species. Subcellular localization study showed that TgLITAF was mainly expressed in the nucleus. qRT-PCR analysis showed that the TgLITAF transcription expressed constitutively in all the examined tissues with the highest expression level in the gills. After LPS or V. alginolyticus treatment, expression of TgLITAF in hemocytes was both up-regulated significantly at 3-6 h. Furthermore, in vitro study indicated that overexpression of TgLITAF in HeLa cells resulted in the activation of TNFα, p53, and influenced the expression levels of apoptotic-related genes Bax, Bcl-2, Caspase-3, Caspase-6, and Caspase-7. The proliferation of HeLa cells was inhibited by overexpression of TgLITAF. Apoptotic fluorescence assay further revealed that TgLITAF participated in the apoptotic process of HeLa cells. Western blotting analysis showed that overexpression of TgLITAF increased endogenous level of cleaved Caspase-7. Taken together, these results revealed that TgLITAF participates in the innate immune response to the pathogen invasion in blood clams and induces apoptosis in HeLa cells.

Endocrine-disrupting chemicals impair the innate immune prophenoloxidase system in the intertidal mud crab, Macrophthalmus japonicus

Endocrine-disrupting chemicals (EDCs), xenobiotics that interfere with endogenous hormone function, have been studied for their impacts in aquatic environments. However, there is limited information about the potentially hazardous impact of bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) on the marine environment. The aim of this study was to investigate the effects of BPA and DEHP on the immune response of the intertidal mud crab, Macrophthalmus japonicus. In order to examine immunological responses involving the prophenoloxidase (proPO) system, mRNA transcript and activity levels of six immune-related genes, including lipopolysaccharide and β-1,3-glucan-binding protein (LGBP), proPO, phenoloxidase (PO), peroxinectin (PE), serine protease inhibitor (Serpin), and trypsin (Tryp), were assessed in M. japonicus hepatopancreas and gills exposed to BPA or DEHP. Expression of immune genes generally decreased in M. japonicus hepatopancreas and gills exposed to all concentrations of BPA by days 4 and 7. However, at day 1, expression of Serpin and Tryp genes was significantly increased in M. japonicus hepatopancreas and gills exposed to BPA. For DEHP exposure, all genes, with the exception of Serpin, were significantly downregulated in M. japonicus gills. In the hepatopancreas, gene expression of PO, proPO, and LGBP increased at day 1, and then decreased by day 7, while mRNA expression of Serpin and Tryp exhibited up-regulation over all exposure periods. In addition, PE gene expression was upregulated in hepatopancreas at day 7 in a dose-dependent manner. Taken together, these results indicated that the crab immune responses were perturbed by exposure to BPA, and, in particular, DEHP.

Gold nanoparticles exposure modulates antioxidant and innate immune gene expression in the gills of Sparus aurata

This study aimed to assess antioxidant and immune gene transcription alterations in the gills of Sparus aurata exposed during 96 h to 4, 80, and 1600 μg/L of gold nanoparticles (AuNPs) coated with citrate or polyvinyl pyrrolidone (PVP). After 96 h of exposure, gr and cat mRNA levels decreased for all tested concentrations of AuNPs, for both coatings. Instead, gst3 mRNA increased after exposure to 1600 μg/L AuNPs (both coatings) and prdx6 increased after exposure to 1600 μg/L AuNPs-citrate. Concerning immune genes, il1β mRNA levels increased after exposure to 80 μg/L AuNPs-citrate and 1600 μg/L AuNPs-PVP and cox2 mRNA showed increased levels in fish exposed to 1600 μg/L AuNPs-citrate. Results indicate that AuNPs with distinct coatings induced different gene expression profiles in gills, though most of the studied genes remained unaltered for the tested conditions.

Genotoxicity of spent pot liner as determined with the zebrafish (Danio rerio) experimental model

Spent pot liner (SPL) is a solid waste generated during the primary smelting of aluminum, and its toxicity is attributed to the presence of fluoride, cyanide, and aluminum salts, which can be leached into aquatic ecosystems. Since the effects of this waste on aquatic life forms have not yet been investigated, the objective of our study was to evaluate the toxicity of simulated leachates of SPL on zebrafish (Danio rerio). Animals were exposed to 0 (control), 0.32, 0.64, or 0.95 g L^-1 of SPL for 24, 72, and 96 h, and genotoxicity was accessed through micronucleus and comet assays. All of the tested treatments induced DNA fragmentation, and the observed frequency of micronuclei and damaged nucleoids generally increased with increasing SPL concentration. The highest frequency of micronuclei (3.3 per 3000 erythrocytes) was detected after 96 h of exposure with 0.95 g L^-1 SPL. In the comet assay, nucleoids classified with highest level of damage in relation to the control were observed principally after 24 and 96 h of exposure. The data obtained in this study confirm the genotoxicaction and mutagenic potential of SPL and indicate that open-air deposits of the waste material could represent a health risk to humans and ecosystems alike.

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

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

Molecular cloning, characterization and functional analysis of a putative mitogen-activated protein kinase kinase kinase 4 (MEKK4) from blood clam Tegillarca granosa

The mitogen-activated protein kinase (MAPK) cascades stand for one of the most important signaling mechanisms in response to environmental stimuli. In the present study, we cloned and identified for the first time the full-length cDNA of MAPK kinase kinase 4 (TgMEKK4) from Blood clam Tegillarca granosa using rapid amplification of cDNA ends method. The full-length cDNA of TgMEKK4 was of 1605 bp in length, encoding a polypeptide of 364 amino acids with a predicted molecular mass of 41.22 kDa and theoretical isoelectric point of 6.29. The conserved MEKK4-domain was identified in TgMEKK4 by SMART program analysis. Homology analysis of the deduced amino acid sequence of TgMEKK4 with other known sequences revealed that TgMEKK4 shared 58%-80% identity to MEKK4s from other species. TgMEKK4 mRNA transcripts could be detected in all tissues examined with the highest expression level in the gill by qRT-PCR. The mRNA expression of TgMEKK4 was up-regulated significantly in hemocytes after Vibrio parahaemolyticus, Vibrio alginolyticus and Lipopolysaccharide (LPS) challenges. Overexpression of TgMEKK4 in HEK 293T cells resulted in the activation of JNK and ERK, but not p38. Consistently, In vivo study indicated that LPS stimulation enhanced JNK, ERK and p38 phosphorylation in blood clams. These results suggest that TgMEKK4 is a powerful factor in the regulation of genes that may be involved in innate immune response of blood clam.

c-Jun N-terminal kinase (JNK) is involved in immune defense against bacterial infection in Crassostrea hongkongensis

c-Jun N-terminal kinase (JNK) is a universal and essential subgroup of the mitogen-activated protein kinase (MAPK) superfamily, which is highly conserved from yeast to mammals and functions in a variety of physiological and pathological processes. In this study, we report the first oyster JNK gene homolog (ChJNK) and its biological functions in the Hong Kong oyster Crassostrea hongkongensis. The ChJNK protein consists of 383 amino acids and contains a conserved serine/threonine protein kinase (S_TKc) domain with a typical TPY motif. Phylogenetic analysis revealed that ChJNK shared a close evolutionary relationship with Crassostrea gigas JNK. Quantitative RT-PCR analyses revealed broad expression patterns of ChJNK mRNA in various adult tissues and different embryonic and larval stages of C. hongkongensis. When exposed to Vibrio alginolyticus or Staphylococcus haemolyticus, ChJNK mRNA expression levels were significantly up-regulated in the hemocytes and gills in a time-dependent manner. Additionally, subcellular localization studies that ChJNK is a cytoplasm-localized protein, and that its overexpression could significantly enhance the transcriptional activities of AP-1-Luc in HEK293T cells. In summary, this study provided the first experimental demonstration that oysters possess a functional JNK that participates in host defense against bacterial infection in C. hongkongensis.

A novel innexin2 forming membrane hemichannel exhibits immune responses and cell apoptosis in Scylla paramamosain

Innexins are a class of transmembrane proteins that are important for embryonic development, morphogenesis and electrical synapse formation. In the present study, a novel innexin2 gene from Scylla paramamosain was named Sp-inx2 and characterized. The complete cDNA and genomic DNA sequences of Sp-inx2 were revealed. Sp-inx2 mRNA transcripts were distributed in various tissues of S. paramamosain and were most abundant in the hemocytes. The Sp-inx2 was significantly upregulated in hemocyte, gill and hepatopancreas tissues with the challenge of either Vibrio alginolyticus, Vibrio parahaemolyticus or lipopolysaccharides (LPSs) when analyzed at 3 and 6 h using quantitative real-time PCR, suggesting that it could activate an immune response against the challenge of LPSs or Vibrio species. Using the chemical inhibitors carbenoxolone and probenecid, the absorption of the fluorescent dye Lucifer yellow decreased in the primary cultured hemocytes of crabs, thus confirming that hemichannels composed of Sp-inx2 existed in the crab hemocytes. With LPS stimulation, the level of mRNA transcripts and protein expression of Sp-inx2 in the same cultured hemocytes gradually increased from 6 to 48 h, while the activity of hemichannels was down-regulated at 6 and 12 h, demonstrating that LPSs could modulate the absorption activity of hemichannels in addition to its upregulation of Sp-inx2 gene expression. Furthermore, the dye uptake rate in HeLa cells in which Sp-inx2 was ectopically expressed increased dramatically but the increase was significantly down-regulated with the addition of 50 μg mL(-1) LPS, suggesting that the LPS stimulation could effectively reduce the activity of hemichannels. Interestingly, with the ectopic expression of Sp-inx2 in HeLa and EPC cells, apoptosis spontaneously occurred in both cultured cell lines when detected using TUNEL assay. In summary, a new Sp-inx2 gene was first characterized in a marine animal S. paramamosain and it had a function associated with immune response and cell apoptosis.

Gill histopathologies following exposure to nanosilver or silver nitrate

Fish gill is the site for many crucial physiological functions. It is among the first sites of xenobiotic exposure, and gill histopathological alterations may be detected soon after toxicant exposure. Silver (Ag) is one of the most toxic metals to aquatic organisms mainly due to its ability to disrupt ionic regulation. The goal of this study was to determine the effect of ionic and nanoscale Ag on fathead minnow gills by examining gill histology and Na(+)/K(+)-ATPase immunoreactivity. Fathead minnows were exposed to two measured concentrations of silver nitrate (AgNO3: 1.3 or 3.7 μg/L as Ag(+)), citrate silver nanoparticles (citrate-AgNP: 15 or 39 μg/L), and polyvinylpyrrolidone-AgNP (PVP-AgNP) (AgNP: 11 or 50 μg/L). Circulatory disturbances were the most prevalent gill alterations detected and were significantly increased in all Ag treatment groups compared to control. AgNO3 (1.3 μg/L) was the only treatment that significantly elevated the number of total mucous goblet cells present. In all other Ag treatments, the percent of degenerated goblet cells was significantly increased compared to control. When the sum of all histopathological abnormalities (weighted index) was calculated, all Ag groups displayed a significantly higher index, with citrate-AgNP having the highest toxicity (index of 10 ± 0.32 versus 2.4 ± 0.6 in controls). Gill Na(+)/K(+)-ATPase immunoreactivity was decreased by Ag. These results indicated that both AgNO3 and AgNP created similar disruptions in gill structure and ionic regulation, possibly due to the ionic Ag portion of each treatment.

Alteration in Pimephales promelas mucus production after exposure to nanosilver or silver nitrate

The fish gill's ability to produce mucus effectively is a critical part of the stress response and protection against xenobiotic toxicity. Adult fathead minnows were exposed to silver nitrate (0.82 µg/L or 13.2 µg/L), polyvinylpyrrolidone-coated silver nanoparticles (11.1 µg/L or 208 µg/L), and citrate-coated silver nanoparticles (10.1 µg/L or 175 µg/L) for 96 h. Mucus concentrations based on glucose as a surrogate were determined at 0 h, 1 h, 2 h, 3 h, 4 h and 24 h after re-dosing each day. Higher mucus production rates following silver treatment were observed at the beginning as compared to controls and compared to after 3 d of exposure. Control fish produced consistent mucus concentrations throughout the exposure (0.62 mg/L and 0.40 mg/L at 24 h and 96 h, respectively). Following 24 h of exposure, all silver treatment groups produced significantly more mucus than controls. Following 96 h of exposure, mucus concentrations in treatment groups were significantly reduced compared with each respective treatment at 24 h. Reduced mucus production following long-term silver exposure could prevent the gills from removing silver, and thus increase toxicity.

Characteristic and functional analysis of a ficolin-like protein from the oyster Crassostrea hongkongensis

Ficolins are a group of soluble animal proteins with multiple roles in innate immunity. These proteins recognize and bind carbohydrates in pathogens and activate the complement system, leading to opsonization, leukocyte activation, and direct pathogen killing, which have been reported in many animal species but might not be present in the shellfish lineage. In the present study, we identified the first fibrinogen-related protein from the oyster, Crassostrea hongkongensis. This novel ficolin-like protein contains a typical signal peptide and a fibrinogen-related domain (designated ChFCN) at the N and C termini, respectively, but does not contain the additional collagen-like domain of ficolins. The full-length cDNA of ChFCN is 1105 bp, encoding a putative protein of 297 amino acids with the molecular weight of 35.5 kD. ChFCN is ubiquitously expressed in selected tissues, with the highest expression level observed in the gills. The temporal expression of ChFCN following microbe infection shows that the expression of ChFCN in hemocytes increases at 3 h post-challenge. The ChFCN protein expression was also examined, and fluorescence microscopy revealed that deChFCN (truncated signal peptide) is located in the cytoplasm of HeLa cells. Full-length ChFCN was detected in the medium supernatant by western blot analysis. Recombinant ChFCN proteins with the molecular weight about 50 kD bind Saccharomyces cerevisiae, Staphylococcus haemolyticus or Escherichia coli K-12, but not those from Vibrio alginolyticus. Furthermore, the rChFCN protein could agglutinate Gram-negative bacteria E. coli K-12 and enhance the phagocytosis of C. hongkongensis hemocytes in vitro. These results indicate that ChFCN might play an important role in the immunity response of oysters.

Cloning and characterization of an apoptosis-related DNA fragmentation factor (DFF) from oyster, Crassostrea hongkongensis

Apoptosis plays an important pathophysiological role in the homeostasis of immune systems. DNA fragmentation factors (DFFs) have been shown to be essential for DNA fragmentation, and the resultant DNA fragments follow a laddering pattern during apoptosis in vertebrates. In invertebrates, the functions of the DFF orthologs are not well characterized; therefore, we cloned and characterized a bivalve DFFA ortholog from the Hong Kong oyster Crassostrea hongkongensis (designated ChDFFA). The full-length cDNA of ChDFFA is 1186 bp in length and encodes a putative protein of 200 amino acids that contains an N-terminal CAD domain and a DFF-C domain at its C-terminus. Real-time RT-PCR results showed that ChDFFA is ubiquitously expressed in several tissues, and its highest expression is in gill. Following a 3- to 48-h challenge by microbial infection, the expression of ChDFFA increased in hemocytes. Using fluorescence microscopy, ChDFFA was localized in nuclei when exogenously expressed in HeLa cells. In addition, over-expression of ChDFFA inhibited the transcriptional activities of p53/p21-Luc reporter genes in HEK293T cells. These results suggest that ChDFFA may be involved in immune response reactions in the Hong Kong oyster C. hongkongensis.

Molecular characterization, expression and function analysis of a five-domain Kazal-type serine proteinase inhibitor from pearl oyster Pinctada fucata

Serine proteinase inhibitors represent an expanding superfamily of endogenous inhibitors that are regulate proteolytic events and involved in a variety of physiological and immunological processes. A five-domain Kazal-type serine proteinase inhibitor (poKSPI) was identified and characterized from pearl oyster Pinctada fucata based on expressed sequence tag (EST) analysis. The full-length cDNA was 737 bp with an open reading frame (ORF) 660 bp encoding a 219 amino acid protein a theoretical molecular weight (Mw) of 23.3 kDa and an isoelectric point (pI) of 8.40. A putative signal peptide of 19 amino acid residues and five tandem Kazal domains were identified. Four of the Kazal domains had the highly conserved motif sequences with six cysteine residues responsible for the formation of disulfide bridges. The deduced amino acid sequence of the poKSPI shared high homology with KSPIs from Hirudo medicinalis. The poKSPI mRNA could be detected in all examined tissues, the expression level of the poKSPI mRNA was the highest in mantle and gonad, while the lowest in haemocyte and intestine. After LPS challenge, the expression level of the poKSPI mRNA in digestive gland was significantly up-regulated at 4 h post-challenge and reached the peak at 12 h post-challenge, which was 4.23-fold higher than control group; the expression level of the poKSPI mRNA in gill was also significantly up-regulated at 8 and 12 h post-challenge, which were 4.48 and 2.26-fold higher than control group. After Vibrio alginolyticus challenge, the expression levels of the poKSPI mRNA in digestive gland were significantly up-regulated at 8, 12, 48 and 72 h post-challenge, which were 1.70, 1.79, 3.89 and 5.69-fold higher than control group, respectively; the expression level of the poKSPI mRNA in gill was significantly up-regulated at 24 h post-challenge, which was 5.30-fold higher than control group. The recombinant poKSPI protein could inhibit chymotrypsin and trypsin activities in dose-dependent manner, when the ratios of rpoKSPI to chymotrypsin and trypsin were 36:1 and 72:1, respectively, the proteinase activities of chymotrypsin and trypsin could be almost completely inhibited, but the rpoKSPI could not inhibit subtilisin.

Molecular characterization and expression analysis of interferon-gamma-inducible lysosomal thiol reductase (GILT) gene from pearl oyster Pinctada fucata

Interferon-gamma-inducible lysosomal thiol reductase (GILT) is an important thiol reductase, involved in class, MHC-restricted antigen processing by catalyzing disulfide bond reduction in mammals. Herein, we describe the identification and characterization of pearl oyster Pinctada fucata GILT (designated as poGILT). The poGILT cDNA was 1273bp long and consisted of a 5'-untranslated region (UTR) of 24bp, a 3'-UTR of 484bp with two cytokine RNA instability motifs (ATTTA), and an open reading frame (ORF) of 765bp encoding a polypeptide of 254 amino acids with an estimated molecular mass of 28.9kDa and a theoretical isoelectric point of 7.4. The N-terminus of the poGILT was found to have a putative signal peptide with a cleavage site amino acid position at 19-20. SMART analysis showed that the poGILT contained a GILT active-site C(69)PDC(72) motif and a GILT signature motif C(115)QHGKEECIGNLIETC(130). Homology analysis of the deduced amino acid sequence of the poGILT with other known GILT sequences by MatGAT software revealed that the poGILT shared 42.9-67.3% similarity and 22.9-49.8% identity to the other known GILT sequences. The expression level of poGILT mRNA was higher in digestive gland, moderate in adductor muscle, gills, gonad, intestine and mantle, and lower in hemocytes. The poGILT mRNA expression was significantly up-regulated in gill and digestive gland after LPS or V. alginolyticus stimulation, respectively. These results suggested that the poGILT was a constitutively expressed acute-phase protein, the expression of which can be enhanced after LPS or V. algrinolyticus stimulation, perhaps involved in the innate immune response of pearl oyster.

Molecular characterization and expression analysis of a putative LPS-induced TNF-alpha factor (LITAF) from pearl oyster Pinctada fucata

The lipopolysaccharide-induced TNF-alpha factor (LITAF) is a novel transcription factor, which plays an important role in regulating the expression of TNF-alpha and various inflammatory cytokines in response to LPS stimulation and forms a dependent signaling pathway separated from NF-kappaB. Herein, we described the identification and characterization of pearl oyster Pinctada fucata LPS-induced TNF-alpha factor gene (designated as poLITAF). The poLITAF cDNA was 932 bp long and consisted of a 5'-untranslated region (UTR) of 45 bp, a 3'-UTR of 497 bp with two cytokine RNA instability motifs (ATTTA), and an open reading frame (ORF) of 390 bp encoding a polypeptide of 129 amino acids with an estimated molecular mass of 13.5 kDa and a theoretical isoelectric point of 8.36. A LITAF domain at C-terminal was identified in the poLITAF using SMART analysis, which contained two conserved CXXC motifs. Homology analysis of the deduced amino acid sequence of the poLITAF with other known LITAF sequences by MatGAT software revealed that the poLITAF shared 44.2-67.4% similarity and 35.4-50.0% identity to the other known LITAF sequences. The expression level of poLITAF mRNA was the highest in digestive gland and gill, moderate in adductor muscle, gonad, intestine and mantle, the lowest in haemocytes. The poLITAF mRNA expression was significantly up-regulated at 24 h in gill and at 12 h in digestive gland after LPS stimulation respectively. These results suggested that the poLITAF was a constitutive and inducible acute-phase protein that perhaps involved in the innate immune response of pearl oyster.

An immune responsive complement factor D/adipsin and kallikrein-like serine protease (PoDAK) from the olive flounder Paralichthys olivaceus

The cDNA encoding of a complement factor D/adipsin and kallikrein-like serine protease, designated PoDAK, was isolated from the olive flounder Paralichthys olivaceus. PoDAK cDNA encodes a polypeptide with 277 amino acids containing conserved catalytic triad residues of serine proteases. The amino acid sequence of PoDAK showed high similarity to the kallikrein-like protein of medaka, mammalian adipsin/complement factor D and tissue kallikrein homolog, KT-14 of trout, complement factor D of zebrafish, and shared 31.6-36.8% homology with complement factor D/adipsin known from other species, including mammals. Phylogenetic analysis revealed that PoDAK clustered with the kallikrein-like protein of medaka and mammalian adipsin/complement factor D and tissue kallikrein homolog KT-14 of trout. The expression of PoDAK mRNA was high in the gills and heart, moderate in muscle, liver, intestine, stomach, kidney, and spleen of healthy flounder, and increased in the kidney, liver, and spleen of flounder challenged by the viral hemorrhagic septicemia virus (VHSV) or Streptococcus iniae. In situ hybridization confirmed that PoDAK mRNA is localized in the kidney and heart of individuals infected with VHSV. Further investigations are needed to clarify the function of PoDAK in vivo and in vitro.

Effects of propanil on the European eel Anguilla anguilla and post-exposure recovery using selected biomarkers as effect criteria

The aim of this study was to assess the physiological response of Anguilla anguilla to propanil and the degree of recovery after being moved to clean water. Preliminary acute toxicity test was carried out in the laboratory and the median lethal concentration (LC50) at 96 h was calculated as 31.33 mg/L (29.60-33.59 mg/L). NOEC and LOEC values (at 96 h) were also calculated as 20 and 25mg/L, respectively. The fish were exposed to 0.63 and 3.16 mg/L of propanil for 72 h and allowed to recover for 144 h. Total proteins (TPs), gamma-glutamil transpeptidase (gamma-GT), alanin aminotransferase (AlAT), alkaline phosphatase (AP), lactate dehydrogenase (LDH) and water content (WC) were assayed in muscle and liver tissues, liver somatic index (LSI) was also determined. Liver TPs and gamma-GT activity decreased after propanil exposure while AlAT and LDH increased. Muscular AP, AlAT and proteins decreased in intoxicated eels while LDH and gamma-GT activities increased. WC increased in both tissues after herbicide exposure as well as LSI. These results revealed that propanil affects the intermediary metabolism of A. anguilla and that the assayed enzymes can be used as good biomarkers of herbicide contamination. However a longer recovery period should be necessary to re-establish eel physiology. The parameters measured in the present study can be used as herbicide toxicity indicators and are recommended for environmental monitoring assessments.

A stereological study of copper toxicity in gills of Oreochromis niloticus

Stereological methods were used to estimate the volumetric density (V(V)) of the filamentar epithelium (FE, 39%), lamellae (L, 28%), central venous sinus (CVS, 14%), central axis (16%), mucous cells (MC, 2%) and chloride cells (CC, 1%) in the gill filament of control Nile Tilapia. The relative volumes of FE and L, and the relative volumes of CVS and central axis, varied inversely under exposure to copper, with high copper toxic levels declanching a chronic defence mechanism that was, nevertheless, overcome, and low copper toxic levels causing adaptation within a moderate acute phase type of response. Copper also induced a decrease of the V(V) (MC, gill filament) due to reduction of surface MC, despite the marked increase of stem MC at chronic exposure to high copper toxic levels. Diminution of the numerical density of filamentar CC was responsible for the decreased V(V) (CC, gill filament), although lamellar CC significantly increased at chronic exposure to low copper toxic levels. The present results demonstrate that cell relative volumes, mean volumes and numerical densities are dependent on the variations of the FE and L, which without a quantitative approach may be misinterpreted, thus stressing the importance of using stereological tools for analyzing histopathological patterns.

Cloning, characterization and expression analysis of the gene for a putative lipopolysaccharide-induced TNF-alpha factor of the Pacific oyster, Crassostrea gigas

Lipopolysaccharide-induced TNF-alpha factor (LITAF) is an important transcription factor that mediates the expression of inflammatory cytokines, including TNF-alpha, in lipopolysaccharide (LPS)-induced processes. In the present study, the Pacific oyster Crassostrea gigas LITAF (Cg-LITAF) gene was cloned and characterized. The full-length Cg-LITAF cDNA consists of 906bp and encodes a polypeptide of 115 amino acids. The Cg-LITAF gene consists of three exons and two introns, with a length of approximately 1.8kb. The Cg-LITAF protein showed 34-45% amino acid sequence identity with other known LITAF sequences. Although the Cg-LITAF coding sequence (115 aa) is shorter than all previously reported LITAF genes, the LITAF domain which contains two CXXC motifs is well conserved. An in vivo expression study showed that Cg-LITAF mRNA was expressed predominantly in gills and moderately in digestive gland and labial palps of healthy oysters. The accumulation of Cg-LITAF mRNA in oyster haemocytes determined by real-time PCR showed the peak 12h after bacterial challenge. This expression pattern suggests that Cg-LITAF is a potent factor in the regulation of genes that are involved in innate defence mechanisms.

Tilapia islet grafts are highly alloxan-resistant

We have previously shown that dose-response studies performed in streptozotocin (STZ)-diabetic nude mouse recipients bearing established, functioning islet xenografts can be used to directly compare in vivo STZ-sensitivity between donor species and that tilapia (fish) islet grafts are exceedingly STZ-resistant. Using this method, we tested whether tilapia islets are sensitive to alloxan. Tilapia or rat islets were transplanted under the renal capsules of STZ-diabetic nude mice. Recipients with normal glucose tolerance tests (GTTs) on day 30-35 were injected with increasing i.v. doses of alloxan and blood glucose levels were followed for 5-7 days and then GTTs were repeated. Next, mice were killed and their grafts/native pancreata examined histologically (including insulin stains). Control nude mice were also injected with increasing i.v. doses of alloxan. Based upon non-fasting blood glucose levels, GTT, and graft histology, the following observations were made: (1) Tilapia islet xenografts were uniformly resistant to i.v. doses of 75 mg/kg (n=3), 150 mg/kg (n=4), and 300 mg/kg (n=3). (2) Rat islet recipients became uniformly severely diabetic after alloxan i.v. doses of 50-70 mg/kg (n=6) (i.e., equivalent to the dosage needed to induce diabetes in rats). (3) Control nude mice were severely diabetic at doses of 75 mg/kg (4/5) and 150 mg/kg (n=3/3). Alloxan dose-response studies were also performed in tilapia. Interestingly, tilapia appeared more sensitive than tilapia islet grafts. Although 75 mg/kg i.v. had little effect in tilapia, higher doses caused severe beta cell necrosis, diabetes, and systemic damage; however, this seeming discrepancy can be explained as tilapia have about one-quarter of the blood volume of mice (i.e., as a percentage of body weight) and so the actual concentration in the blood was about 4-fold higher at each dose. We conclude that tilapia beta cells are highly resistant to the beta cell toxin alloxan.

Structural changes in gill DNA reveal the effects of contaminants on Puget Sound fish

Structural differences were identified in gill DNA from two groups of English sole collected from Puget Sound, Washington, in October 2000. One group was from the industrialized Duwamish River (DR) in Seattle and the other from relatively clean Quartermaster Harbor (QMH). Chemical markers of sediment contamination [e.g., polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)] established that the DR was substantially more contaminated than QMH. The levels of these chemicals in the sediments of both sites were consistent with levels of cytochrome P450 1A (CYP1A) expression in the gills of English sole from the same sites. Structural differences in gill DNA between the groups were evinced via statistical models of Fourier transform-infrared (FT-IR) spectra. Marked structural damage was found in the gill DNA of the DR fish as reflected in differences in base functional groups (e.g., C-O and NH2) and conformational properties (e.g., arising from perturbations in vertical base stacking interactions). These DNA differences were used to discriminate between the two fish groups through principal components analysis of mean FT-IR spectra. In addition, logistic regression analysis allowed for the development of a "DNA damage index" to assess the effects of contaminants on the gill. The evidence implies that environmental chemicals contribute to the DNA changes in the gill. The damaged DNA is a promising marker for identifying, through gill biopsies, contaminant effects on fish.

Ecotoxicology and innate immunity in fish

This review summarizes the scattered literature on the effects of toxicants on the external and internal innate immunity of fish. Insecticides, heavy metals and surfactants have been the most frequently examined toxicants, whereas dioxins, furans and polychlorinated biphenyls have been tested less frequently. Studies to date have been conducted at the levels of cells in vitro, of fish in the laboratory and microcosms, and also of fish in the field. Among innate immune parameters, phagocyte respiratory burst appears especially sensitive to toxicants. Toxicant-induced alterations in external mucous production have also been observed repeatedly. Field studies have occasionally examined changes to melano-macrophage centers, but the meaning of such changes is not clear. Advances in basic knowledge of fish innate immunity should lead to improvements in monitoring fish health and predicting the impact of toxicants on fish populations, which is a fundamental ecotoxicological goal.