Sublethal Concentrations Of Atrazine Research Articles

Histoarchitectural Alterations in Various Tissues of Poecilia sphenops Exposed Three Sub Lethal Concentrations of Atrazine

Histoarchitectural Alterations in Various Tissues of Poecilia sphenops Exposed Three Sub Lethal Concentrations of Atrazine

Atrazine promotes immunomodulation by melanomacrophage centre alterations in spleen and vascular disorders in gills from Oreochromis niloticus

Atrazine is a herbicide that is banned in Europe but remains widely used on different types of crops in several countries in the American continent. Atrazine is known to be an endocrine disruptor and its effects on gonads have been extensively reported, but the toxic action on other organs is poorly documented. In this paper, we investigated the toxicity of atrazine on the gills and spleens of Nile tilapia (Oreochromis niloticus). The median lethal concentration (LC50), capable of killing one-half of the test animals was calculated, and sublethal concentrations of atrazine were used in a semistatic and subchronic assay. The following four experimental groups were formed: control not exposed to atrazine, a group exposed to 1 ppm atrazine for 15 days, a group exposed to 2 ppm for 7 days, and a group exposed to 2 ppm for 15 days. The concentrations were verified during the study by high performance liquid chromatography. The gills and spleens were stained with hematoxylin and eosin and histopathological findings were made. The Perls technique was used on the spleens to identify hemosiderin, lipofuscin, and melanin pigments in the cells from melanomacrophage centres (MMCs). The spleens were submitted to proliferating cell nuclear antigen (PCNA) and inducible nitric oxide synthase (iNOS) immunohistochemistry, and morphometry was used to assess splenocyte proliferation and melanomacrophage iNOS expression. Finally, a colorimetric assay for caspase-3 was performed on the spleens to identify apoptosis. Vascular and structural alterations, such as venous sinus congestion, aneurysm, hemorrhage, pillar cell hypertrophy, disarrangement of secondary lamellae, and epithelial lifting were observed in the gills. The frequency of individuals with aneurysms was higher in the groups treated with 2 ppm than in other groups. Atrazine had an immunomodulatory effect on the spleen, observed by the alteration in the percentage of red and white pulp, alteration of the MMC area, changes in the melanomacrophage pigment content, slight iNOS suppression, decrease in splenocyte proliferation under 1 ppm atrazine, and increased caspase 3 activity under 2 ppm atrazine after 7 and 15 d. Such effects could compromise oxygenation and the immune response and, ultimately, the survival and fitness of the fish.

Toxicity of atrazine and nonylphenol in juvenile rainbow trout (Oncorhynchus mykiss): Effects on general health, disease susceptibility and gene expression

Atrazine (ATZ) and nonylphenol (NP) are commonly identified contaminants in aquatic habitats; however, few studies have considered the impact of these endocrine disrupters on immune function and resistance to disease. This study examined the immunotoxicological effects of ATZ and NP at multiple levels of biological organization. Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to a solvent control (0.00625%, v/v anhydrous ethanol), or sub-lethal concentrations of ATZ (59μg/L and 555μg/L) or NP (2.3μg/L or 18μg/L) for 4d. At the end of exposure, fish were assessed for a number of physiological endpoints, including a host resistance challenge, and liver gene expression was assessed using a salmonid microarray (cGRASP, 32K version 1). While the low ATZ and low NP treatments had no measurable effects on the physiological endpoints measured, fish exposed to the high ATZ concentration (555μg/L) exhibited significantly elevated plasma cortisol, a decrease in SSI, and decreased lymphocytes and increased monocytes in peripheral blood, with suppression of early immune system processes apparent at the molecular level. In contrast, fish exposed to the high NP concentration (18μg/L) showed physiological (e.g. significantly elevated LSI) and gene expression changes (e.g. induction of vitellogenin) consistent with estrogenic effects, as well as decreased lymphocytes in the peripheral blood and more limited alterations in immune system related pathways in the liver transcriptome. Fish exposed to high ATZ or NP concentrations incurred higher mortality than control fish following a disease challenge with Listonella anguillarum, while fish exposed to the lower concentrations were unaffected. Microarray analysis of the liver transcriptome revealed a total of 211 unique, annotated differentially regulated genes (DRGs) following high ATZ exposure and 299 DRGs following high NP exposure. Functional (enrichment) analysis revealed effects on immune system function, metabolism, oxygen homeostasis, cell cycle, DNA damage, and other processes affected by ATZ or NP exposure. Overall, this study provides evidence at multiple levels of biological organization that both ATZ and NP are immunotoxic at sub-lethal concentrations and highlights the potential risk posed by these chemicals to wild fish populations.

Effects of atrazine and iridovirus infection on survival and life‐history traits of the long‐toed salamander (Ambystoma macrodactylum)

Environmental contaminants and emerging infectious diseases are implicated as factors contributing to global amphibian declines. However, few studies have tested the interaction of these factors. We exposed six-week-old, larval long-toed salamanders (Ambystoma macrodactylum) to Ambystoma tigrinum virus (ATV; 0 or 10(3.5) plaque-forming units/ml) and sublethal concentrations of atrazine (0, 1.84, 18.4, and 184 microg/L) in a 4 x 2 factorial design for 30 d. We tested the effects of atrazine and virus on mass and snout-vent length (SVL) at metamorphosis and larval period as well as on rates of mortality and viral infectivity. We confirmed ATV transmission to A. macrodactylum via polymerase chain reaction, but infection rates were lower than expected, consistent with the theory predicting lower pathogen transmission to nonnative hosts. Larvae exposed to both atrazine and ATV had lower levels of mortality and ATV infectivity compared to larvae exposed to virus alone, suggesting atrazine may compromise virus efficacy. The highest atrazine level (184 microg/L) accelerated metamorphosis and reduced mass and SVL at metamorphosis significantly relative to controls. Exposure to ATV also significantly reduced SVL at metamorphosis. The present study suggests moderate concentrations of atrazine may ameliorate effects of ATV on long-toed salamanders, whereas higher concentrations initiate metamorphosis at a smaller size, with potential negative consequences to fitness.

Lipid synthesis by isolated duckweed (Lemna minor) chloroplasts in the presence of a sublethal concentration of atrazine

We have examined the effects of a sublethal concentration of atrazine on the incorporation of sodium-[U-14C] acetate into isolated chloroplast lipids of Lemna minor. A high level of [14C]-acetate was incorporated into diacylgalactosylglycerol (DGG) and diacylglycerol (DAG). Consequently, the conversion of phosphatide acid to DAG and that of DAG to DGG seems to be as active in L. minor (an "18:3-plant") as in "16:3-plants." Chloroplast lipids from atrazine-treated plants were more extensively labelled with [14C]-acetate than the control plants. These results are in agreement with our previous in vivo studies which suggest that sublethal concentrations of atrazine stimulate the lipid metabolism of L. minor to form more thylakoid membranes. Furthermore, the specific radioactivity of linolenic acid was the highest in DAG and the lowest in DGG. These data suggest that desaturation of linoleic acid to linolenic acid mainly occurs before the galactosylation of DAG to form DGG in L. minor.

Effets physiologiques de l'atrazine à doses sublétales sur Lemna minor L. IV. Influence sur la composition lipidique

The lipids and the fatty acids of duck weed (Lemna minor L.), cultivated aseptically during 5, 10, or 15 days in mineral solution containing sublethal concentrations of atrazine (0.05 to 0.75 ppm), were analysed by thin-layer and gas–liquid chromatography. All concentrations of atrazine used, independently of age of plants, increased the total fatty acid content, except for 5-day plants at 0.50 and 0.75 ppm atrazine where a decrease in total fatty acids was observed. α-Linolenic acid content increased while linoleic acid content decreased. Sublethal concentrations of atrazine increased the percentage of monogalactosyldiacylglycerol compared with total phospholipids and total neutral lipids. Monogalactosyldiacylglycerol was the main lipid involved in the α-linolenic acid increase observed in the total fatty acids. The increase in α-linolenic acid and in monogalactosyldiacylglycerol in the presence of sublethal concentrations of atrazine is an indication that these treatments maintain intact and fully functional chloroplast membranes.