Effects of sublethal levels of tributyltin chloride on a new toxicity test organism,Liza saliens (osteichthyes, mugilidae): a histological study

Retinal toxicity of heavy metals and its involvement in retinal pathology

The objective of the present review is to discuss epidemiological evidence demonstrating the association between toxic metal (Cd, Pb, Hg, As, Sn, Ti, Tl) exposure and retinal pathology, along with the potential underlying molecular mechanisms. Epidemiological studies demonstrate that Cd, and to a lesser extent Pb exposure, are associated with age-related macular degeneration (AMD), while the existing evidence on the levels of these metals in patients with diabetic retinopathy is scarce. Epidemiological data on the association between other toxic metals and metalloids including mercury (Hg) and arsenic (As), are limited. Clinical reports and laboratory in vivo studies have shown structural alterations in different layers of retina following metal exposure. Examination of retina samples demonstrate that toxic metals can accumulate in the retina, and the rate of accumulation appears to increase with age. Experimental studies in vivo and in vitro studies in APRE-19 and D407 cells demonstrate that toxic metal exposure may cause retinal damage through oxidative stress, apoptosis, DNA damage, mitochondrial dysfunction, endoplasmic reticulum stress, impaired retinogenesis, and retinal inflammation. However, further epidemiological as well as laboratory studies are required for understanding the underlying molecular mechanisms and identifying of the potential therapeutic targets and estimation of the dose-response effects.

Distribution of butyltin compounds in Brazil's southern and southeastern estuarine ecosystems: assessment of spatial scale and compartments

Butyltin compounds (BTs), including tributyltin (TBT) and its degradation products, dibutyltin and monobutyltin, have been found in a diversity of aquatic systems and causing toxic effects in target and nontarget organisms. They enter in coastal systems through different sources (as antifouling paints, industrial effluents, etc.) where they interact with biotic and abiotic components, and their distribution is commonly determined by the morphological and hydrodynamic conditions of the coastal systems. In this study, we discuss the contamination by BTs on a spatial scale (eight estuaries with three subareas each) and in different compartments of the estuaries (sediments, suspended particulate matter (SPM), and estuarine catfish tissues (liver and gills). Lower concentrations of BTs were found in the sediments (n.d. to 338 ng g(-1)) in comparison to studies before a ban of TBT in antifouling paints was enacted, mostly indicating an old input or preservation related with sediment properties and composition. For SPM samples (n.d. to 175 ng L(-1)) as well as in fish tissues (n.d. to 1426 ng g(-1)), the presence of these compounds was frequent, especially in the fish due to their movement throughout the estuaries and the potential to assess point sources of BTs. These results indicate that BTs persist in the environment, with variation in amounts between investigated estuaries and even at locations inside the same estuary, because of ideal preservation conditions, transport to remote areas, and input from different sources.

Oxidative stress, genotoxicity and histopathology biomarker responses in Mugil cephalus and Dicentrarchus labrax gill exposed to persistent pollutants. A field study in the Bizerte Lagoon: Tunisia

The use of biomarkers has become an important tool for modern environmental assessment as they can help to predict pollutants involved in the monitoring program. Despite the importance of fish gill in several functions (gaseous exchange, osmotic and ionic regulation, acid-base balance and nitrogenous waste) its use in coastal water biomonitoring focusing on protection and damage is scarce. This field study investigates biochemical (catalase, superoxide dismutase, lipid peroxidation), molecular (DNA integrity) and morphological (histology) parameters in gill of mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) and originating from Bizerte lagoon (a coastal lagoon impacted by different anthropogenic activities) and from the Mediterranean Sea (a reference site). Remarkable alterations in the activities of oxidative stress enzymes and DNA integrity in the tissue of the two studied fish species were detected in Bizerte Lagoon. The study of histopathological alterations of gills in both two fish species from Bizerte Lagoon suggest thickening of primary lamellae, cellular hyperplasia, aneurism, curving, shortening and fusion of secondary lamellae. The adopted approach, considering simultaneously protection responses and damaging effects, revealed its usefulness on the pollution assessment.

Mechanisms by which the antitumor compound di-n-butyl-di-(4-chlorobenzohydroxamato)tin(IV) induces apoptosis and the mitochondrial-mediated signaling pathway in human cancer SGC-7901 cells

The mechanisms by which the strong antitumor diorganotin(IV) compound di-n-butyl-di-(4-chlorobenzohydroxamato)tin(IV) (DBDCT) induces apoptosis of SGC-7901 cells were first investigated. Inhibition of proliferation of four cancer cell lines compared with normal human hepatic L-O2 cells, cancer cell apoptosis, and expression of related mRNA and protein were detected using the methyl thiazolyl tetrazolium (MTT), flow cytometry, reverse transcription polymerase chain reaction (RT-PCR), Western blot, and DNA ladder assays, and electron microscopy and immunocytochemistry. DBDCT decreased cancer cell proliferation rates in a dose- and time-dependent manner and changed the cycle distribution of SGC-7901 cells; the proportion of cells in G(0)-G(1) phase was increased, whereas the numbers in S and G(2)-M phases were decreased. Blockade of the cell cycle was perhaps associated with increased levels of p21, p27, p53 and the decreased level of proliferating cell nuclear antigen (PCNA). Apoptosis was characterized by DNA fragmentation, chromosomal condensation, apoptotic bodies, sub-G(1) peaks, and an increased apoptotic rate, as shown using the annexin V-FITC method. Pretreatment of cells with N-acetylcysteine and caspase-9 inhibitor could reduce growth inhibition and DBDCT-induced apoptosis. The results showed that DBDCT-mediated cell-cycle arrest might occur through the induction of p21 in a p53-dependent manner and that DBDCT induction of the mitochondrial apoptotic signaling pathway is perhaps mediated by increasing Bax/Bcl-2 ratios, which result in the loss of DeltaPsi(m), release of cytochrome c into the cytoplasm, activation of caspase-3 and -9, and increased reactive oxygen species (ROS) generation.

Monitoring pollution in Esmoriz-Paramos lagoon, Portugal: liver histological and biochemical effects in Liza saliens

The Esmoriz-Paramos lagoon is one important ecosystem located in the Northwest coast of Portugal. This study is concerned with the assessment of pollution of the lagoon contributed by urban, industrial and agricultural activities. The parameters selected for this aim were the occurrence of hepatic histological alterations and plasma blood biochemistry in Liza saliens, the dominant fish in this lagoon. Blood parameters were compared between mullets collected from the lagoon and from the sea and included plasma enzyme activities (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)), glucose (GLU) and total protein (TP). A positive relationship between hepatocyte vacuolization index and hepatosomatic index was found, suggesting that lipid accumulation could have contributed to the increase of liver weight. The hepatic alterations recorded included general diagnostic categories and additionally large areas of heterogeneous parenchyma, composed of hepatocytes with different spectrum of vacuolization. Liver histopathological evaluation revealed a sample prevalence of 34% for heterogeneous parenchyma, 31% for foci of necrosis and 9% for non-neoplastic lesions. No neoplastic lesions were found. Livers with heterogeneous parenchyma showed higher Cu and Zn content than livers without this category of lesion, suggesting that metals accumulated could trigger this hepatic alteration. AST was higher in mullets from the lagoon than in mullets from the sea, but no differences in ALP and ALT were found, suggesting a change in protein metabolism as an adaptive response to metals exposure. The higher glucose and protein contents observed in fish caught in the lagoon are consistent with a stress response and the measurement of plasma AST activity could be a sensitive indicator of lagoon fish stress. In conclusion, Esmoriz-Paramos lagoon biomonitorization, using indicator species will proceed to assess the impact of the restoration program under development by the Portuguese government.