Liver is very sensitive to environmental contaminants such as pesticides, it being the first target of toxicity of a substance. The objective of this study was to investigate the possible effects of the insecticide imidacloprid (IMI) on the liver of Oreochromis niloticus according concentrations used for growing sugarcane. A semi-quantitative analysis of histopathological alterations of IMI on liver was performed by light microscopy and cellular labeling of heat shock proteins (HSP70) by immunohistochemistry. The most common changes in liver at all concentrations of IMI were hydropic degeneration, pyknotic nuclei, and loss of cell limits. Steatosis and increased levels of HSP70 were detected in hepatocytes with the highest concentration of IMI. In conclusion, the tested concentrations of IMI induced histopathological changes in the liver of O. niloticus and active defence mechanisms to maintain the morphophysiological integrity of the liver. This insecticide has a toxicity potential for these fish, which is a non-target organism of its action.

Diplopods are considered important macroarthropods the soil as part of its maintenance and balance. These animals usually do not occur in high densities, but population explosions caused by environmental disturbances, climate changes, and use of pesticides that eliminate possible competitors, have been reported. The millipede Urostreptus atrobrunneus Pierozzi and Fontanetti, 2006 have become a nuisance to humans in infestation sites in urban centers of the state of Sao Paulo, Brazil. As a contribution to the understanding of this potential pest, this study describes the histology, histochemistry, and ultrastructure of the U. atrobrunneus midgut, and presents the redefinition of hepatic cells somewhat controversial in the literature. The region of the midgut is characterized by the absence of a cuticular intima, and composed of a pseudostratified epithelium on a thick basal membrane, followed by a muscle layer, a layer of hepatic cells, lined by an external membrane. The morphology observed in U. atrobrunneus is similar to that reported for other species of diplopods. The hepatic cells have been previously described as randomly without forming a layer, however, the present results clearly demonstrate that these cells form a continuous layer over the whole midgut.Keywords: histology, histochemistry, ultrastructure, Diplopoda, digestive tract. Intestino médio do diplópodo Urostreptus atrobrunneus: estrutura, função e redefinição das células hepáticas ResumoDiplópodos são considerados importantes macro-artrópodes do solo, uma vez que participam de sua manutenção e equilíbrio. Comumente estes animais não apresentam população numerosa, porém há relatos de explosões populacionais ocasionadas por desequilíbrios ambientais, mudanças climáticas e utilização de pesticidas que eliminam possíveis competidores. O milípede Urostreptus atrobrunneus Pierozzi e Fontanetti, 2006, têm apresentado pontos de infestação em centros urbanos, do estado de São Paulo, Brasil, causando muitos transtornos à população humana. Com objetivo de contribuir para o conhecimento desta potencial praga, este trabalho apresenta a descrição histológica, histoquímica e ultra-estrutural do intestino médio do milípede U. atrobrunneus, bem como apresenta a redefinição das células hepáticas, um tanto controversa na literatura pertinente. A região do intestino médio é caracterizada pela ausência da íntima cuticular, sendo formado por um epitélio pseudoestratificado, apoiado por uma membrana basal espessa, seguido de uma camada muscular, uma camada de células hepáticas, revestido por uma membrana externa. A morfologia observada neste trabalho assemelha-se bastante com as descrições de outras espécies de diplópodos estudadas até o momento. As células hepáticas foram previamente descritas como dispostas aleatoriamente sem a formação de uma camada, contudo, os presentes resultados demonstram claramente que estas células formam uma camada contínua ao longo de todo o intestino médio.

Large amounts of residues generated by agricultural, urban and industrial activities are dumped daily on the soil. This practice deserves special attention because it causes serious environmental problems. This study evaluated the toxic potential of the sugarcane vinasse, a by-product of the sugar-alcohol industry, and the biosolid, a residue produced by wastewater treatment plants, both widely used as fertilizers. The evaluation was performed through bioassays using a typical soil bioindicator, the diplopod Rhinocricus padbergi. The specimens were exposed to soils containing these residues in concentrations that are compatible with the Brazilian regulation for agricultural use. Semi-quantitative immunolabelling analyses of the stress protein HSP70 were performed on the midgut of the studied diplopods. There was a significant increase in the immunolabelling of HSP70 proteins as a response to xenobiotics from both residues, particularly in regions where the function of the cells is the detoxification of the organ (e.g. the hepatic cell layer and specific regions of the epithelium). Higher immunolabelling was observed in the specimens exposed to vinasse in comparison with the biosolid exposure. This demonstrates that the substances in the tested residues had proteotoxic action in the exposed animals and induced a cytoprotective response, which led to higher stress protein immunolabelling. Therefore, caution is needed for the use of such residues in agriculture.

HSP70 are the most studied proteins and among all HSPs are highlighted due to their high sensitivity and abundance, as well as being ubiquitously expressed and associated with all subcellular compartments. For this reason, this work specifically approaches HSP70, since its multiple responsibilities actively participate in the homeostasis of all living organisms and its rapid response to any agent stressor is efficient in assessing environmental pollution/contamination processes. HSP70, heat shock proteins thus classified according to their molecular weight of 70 kDa, are proteins that have maintained their structures conserved from the most primitive to the most complex organisms. They belong to the chaperone family, which comprises proteins with different structures that share a common function. In general, they participate in the process of correct folding of proteins; however, it has been described that they also participate in numerous complex processes of metabolism; its synthesis can usually be increased or decreased under stressful conditions. The classical activation of this protein is due to the increase in environmental temperature, but several factors can trigger the gene expression process of this protein, not only as the increase or decrease of heat or cold, but also the exposure to substances of a chemical nature, physical or biological (metals, metabolism inhibitors, chemotherapeutic agents, inflammatory and infectious processes, processes leading to cell death, the cycle of cell division itself and growth factors, cellular mechanisms considered normal). Given the broad repercussion of these proteins in metabolic processes and in organism physiology, numerous studies have evaluated the HSP70 production under adverse conditions, highlighting their connection to pollution and environmental contamination. Hence, this work aimed to literature review the vast array of HSP70 metabolic functions and its possible applications as biomarkers in the evaluation of contaminated environments by compiling the different physiological responses observed in various animal groups exposed to different conditions.

The digestive tract of millipedes is a straight tube, differentiated into three large regions: foregut, midgut, and hindgut (Fig. 5.1). Except for the midgut, of mesodermal origin, the other two regions, of ectodermal origin, are internally lined by cuticle (Hopkin & Read, 1992). A pair of salivary glands, or a single one, runs along the foregut and is responsible for the production of a secretion that in addition to lubricating the food, may contain digestive enzymes. From the pylorus, the first portion of the hindgut, a pair of Malphighian tubules arise which play a role in the osmoregulation and excretion of nitrogen residues and inorganic material (Hopkin & Read, 1992; Fantazzini et al., 1998; Moreira-de-Sousa & Fontanetti, 2012). Histological and, to a very limited extent, ultrastrucural studies have been performed in the last fifty years on representatives of most millipede orders, i.e. Polyxenida: Polyx