The use of diplopods in soil ecotoxicology - a review.

Diplopods play an important role in the dynamics of terrestrial ecosystems, actively participating in the decomposition of organic matter and soil aeration. They have gained increased attention from ecotoxicology research because they are continuously exposed to soil contaminants and biological effects of chemical stressors can be measurable at various levels of biological organization. This paper is the first review on the use of diplopods as soil bioindicators and compiles the effects of the different toxic chemical agents on these animals. Special emphasis is given on the interpretation of the effects of heavy metals and complex mixtures in target organs of diplopods.

Morphological alterations of epidermis of rabbits infested by R. sanguineus ticks and exposed to Selamectin (active principle of Pfizer Revolution(®) acaricide): a confocal microscopy study.

The present study analyzed, by means of confocal laser scanning microscopy, the epidermis of rabbits infested by the brown dog tick Rhipicephalus sanguineus and exposed to concentrations of 50%, 80% and 100% of a selamectin-based commercial acaricide (Pfizer's Revolution(®)). The results demonstrated that rabbits exposed to concentrations of 80% and 100% of the Revolution acaricide, which contains 12% selamectin, showed thinning of epithelial tissue of the epidermis with associated cellular disorganization. Individuals exposed to a 50% concentration showed lower epidermal tissue disorganization when compared to those exposed to the higher doses of the acaricide (80% and 100%). Whereas selamectin, when used in higher concentrations (80% and 100% Revolution(®)) can alter the morphology of the epidermis, at lower concentrations (50%), even though still able to eliminate ectoparasites, it causes less toxicity damage to the host. Selamectin can be considered a dose-dependent toxic agent, since higher concentrations increase the morphological changes in the epidermis of the host rabbits.

The occurrence of autophagic cell death in the tegument of rabbits pre-infested with Rhipicephalus sanguineus and exposed to selamectin (active principle of acaricide Pfizer Revolution®).

Ticks of Rhipicephalus sanguineus species have great medical and veterinary importance for being a vector of various diseases. In an attempt to minimize their action on the host, people have resorted to chemical control by using various acaricides, such as selamectin. Although previous studies have demonstrated its toxic action in domestic animals, no studies focused on the detection of cell death when exposed to selamectin. For this reason, the technique for detecting autophagic cell death was used in order to demonstrate the responses of rabbits' skin tissues pre-infested with R. sanguineus and exposed to different concentrations of selamectin. The obtained results when exposed to 100 and 80% concentrations of selamectin showed a strong mark of acid phosphatase on the cells of the connective tissue of the dermis and hair follicles, whereas the ones exposed to the 50% concentration had a weak mark on the cells of the connective tissue of the dermis and moderate staining in hair follicles. It became clear that, when used at high concentrations (100 and 80%), selamectin is capable to induce a large scale occurrence of the autophagic cell death process. On the other hand, the concentration of 50% causes minor morphophysiological changes in the skin of rabbit hosts when evaluated the cell death process. Therefore, the data confirms that selamectin is a powerful dose-dependent toxic agent causes increased activity of the enzyme acid phosphatase.

Histopathology of the tegument of rabbits infested by Rhipicephalus sanguineus (ACARI: IXODIDAE) ticks and exposed to selamectin (active principle of acaricide Revolution, Pfizer).

Ticks are hematophagous ectoparasites which can transmit several diseases to the host during their feeding process. When ticks mechanically damage the tissue, they eventually induce inflammatory responses on the skin spot where they are fixed. One of the alternatives to control these ectoparasites is the use of chemical substances like selamectin-the active principle of Pfizer's antiparasitic Revolution-a macrocyclic lactone capable of doing neurotoxic damage to the tick and eventually eliminating infestation in dogs and cats. The purpose of this study was to analyze, using histological and histochemical techniques, the occurrence of morphophysiological alterations in the skin of the host rabbits exposed to selamectin and infested with Rhipicephalus sanguineus (Acari: Ixodidae). Histologically, the exposed and infested rabbits showed a partial and/or total decrease in the stratum corneum and the epithelium decreased in the number of cell layers, consequently reducing the stratification (thinning) and quite pronounced formations of sub-epidermal edemas with consequent disorganization of collagen fibers in the dermal layer's connective tissue. Histochemical tests showed strong periodic acid-Schiff-positive reaction in the hair follicle and some regions of the dermis, besides resynthesis of collagen fibers detected by Mallory's trichrome technique. The obtained results showed that selamectin acts like a toxicant agent when in contact with the skin of the rabbit infested with ticks, inducing morphophysiological alterations in the acute inflammatory process in the animal's tegument. Selamectin is a chemical substance which has a dose-dependent action since higher concentrations cause greater morphophysiological damage in the skin of rabbits.

Sewage sludge toxicity in edaphic organism: analysis of midgut responses in the diplopod Rhinocricus padbergi.

Diplopods are agile saprophagous invertebrates with the ability to colonize several soil layers. They feed on waste and decaying organic matter, making the soil in which they are present better aerated and mineral-enriched. Because of their habits, diplopods have been suggested to be used in studies to analyze possible toxic effects of impacted soils in edafic fauna. In that respect, this study aimed at checking the feasibility of using morphological analysis from millipede's midgut as a biomarker for soils exposed to sewage sludge from sewage treatment plants. Histological and histochemical techniques, applied to the species Rhinocricus padbergi's midgut, were used. Two sewage sludge samples were used; they were collected in two small towns in the countryside of São Paulo State. Both cities are part of the Piracicaba-Capivari-Jundiaí basin (PCJ-1 and PCJ-3). For 7 and 15-day periods, the animals were exposed to 10% concentrations and crude sludge for the PCJ-1sample and to 1, 10, and 50% concentrations and sludge for the PCJ-3 sample. The material exposed to the PCJ-1 sample showed an increase in the presence of cytoplasmic granules in both concentrations in all periods and a slight increase in the rate of epithelial renewal. The material of PCJ-3 sample presented the same alterations observed in PCJ-1 sample in higher frequence and over that high quantity of neutral polysaccharides in the hepatic cells layer. We can conclude that with the increase of sewage sludge concentrations tested, there is an increase in morphophysiologicals alterations frequencies found in the diplopods' midgut.