Cell markers for ecotoxicological studies in target organs of bees

Bees are important pollinators that, because of extensive deforestation of their natural habitats, now forage widely in agricultural areas. This interaction with human agricultural activity has led to a reduction in the number of bee species because of contact with widely used pesticides. However, little is known about the adverse effects that exposure to such agents has on bee tissues and organs. In this review, we discuss the morphological alterations induced by environmental contaminants in the midgut and Malpighian tubules of bees; these two organs are involved in the absorption and excretion of toxic compounds, respectively. We also discuss the role of heat shock proteins, also known as stress proteins, in the cellular response to chemical compounds, and the importance of cell death as an indicator of the toxicity of these compounds. The analysis of these two cellular markers may be useful for monitoring bees that forage in agricultural areas.

Brochosomes-for-eggs of the Proconiini ( Hemiptera: Cicadellidae, Cicadellinae ) species associated with orchards of Citrus sinensis ( L. ) Osbeck in Rio Grande do Sul, Brazil

Brocossomos são corpos ultramicroscópicos, reticulados, produzidos pelos tubos de Malpighi das cigarrinhas. São geralmente esféricos (brocossomos de tegumento) ou alongados (brocossomos de ovos). Neste estudo, as espécies de Proconiini foram identificadas de acordo com seus brocossomos de ovos. As características e uma chave para a identificação dos brocossomos também foram discutidas. Os espécimes foram coletados em nove pomares de Citrus sinensis ('Valencia'), com o uso da armadilha adesiva de cor amarela. Os pomares estão localizados em sete municípios do Rio Grande do Sul: Tenente Portela, Ijuí, Jaguari, Harmonia, Taquari, Montenegro e Pelotas. Os dados foram coletados de outubro de 1999 a dezembro de 2000 e de outubro de 2001 a março de 2002. Foram identificadas sete espécies capazes de produzir brocossomos de ovos: Acrogonia citrina Marucci & Cavichioli, Homalodisca ignorata Melichar, Molomea consolida Shröder, Molomea lineiceps Young, Molomea magna (Walker), Oncometopia facialis (Signoret), e Oncometopia fusca Melichar. Este estudo demonstra que a diversidade de brocossomos de ovos pode ser uma ferramenta útil para a identificação de espécies de Proconiini.

Changes in nuclear phenotypes following cold shock in Panstrongylus megistus (Burmeister)

The nuclear phenotypes of Malpighian tubule epithelial cells of 5th instar male nymphs of the blood-sucking insect Panstrongylus megistus were studied immediately after a short (1 h) cold shock at 0o.C, and 10 and 30 days later. The objective was to compare the responses to a cold shock with those known to occur after hyperthermia in order to provide insight into the cellular effect of cold in this species. Nuclei which usually exhibited a conspicuous Y chromosome chromocenter were the most frequent phenotype in control and treated specimens. Phenotypes in which the heterochromatin was unravelled, or in which there was nuclear fusion or cell death were more abundant in the shocked specimens. Most of the changes detected have also been found in heat-shocked nymphs, except for nuclear fusion which generates giant nuclei and which appeared to be less effective or necessary than that elicited after heat shock. Since other studies showed that a short cold shock does not affect the survival of more than 14 percent of 5th instar nymphs of P. megistus with domestic habit and can induce tolerance to a prolonged cold shock, heat shock proteins proteins are probably the best candidates for effective protection of the cells and the insects from drastic damage caused by low temperature shocks

Nuclear phenotype changes after heat shock in Panstrongylus megistus (Burmeister)

The nuclear phenotypes of Malpighian tubule epithelial cells of male nymphs of the blood-sucking insect, Panstrongylus megistus, subjected to short- and long-duration heat shocks at 40oC were analyzed immediately after the shock and 10 and 30 days later. Normal nuclei with a usual heterochromatic body as well as phenotypes indicative of survival (unravelled heterochromatin, giants) and death (apoptosis, necrosis) responses were observed in control and treated specimens. However, all nuclear phenotypes, except the normal ones, were more frequent in shocked specimens. Similarly altered phenotypes have also been reported in Triatoma infestans following heat shock, although at different frequencies. The frequency of the various nuclear phenotypes observed in this study suggests that the forms of cell survival observed were not sufficient or efficient enough to protect all of the Malpighian tubule cells from the deleterious effects of stress. In agreement with studies on P. megistus survival following heat shock, only long-duration shock produced strongly deleterious effects.

Changes in the nuclear phenotypes of Triatoma infestans KLug, induced by thermal shocks*

Os fenótipos nucleares de células epiteliais dos túbulos de Malphigi de ninfas de 4§ estadio de Triatoma infestans Klug submetidas a choques de temperatura a 0 gradeC e 40 gradeC por 1 e 12 horas foram investigados imediatamente após o estress e 3 e 30 dias após o mesmo. Além dos fenótipos usualmente descritos para os espécimes controle, nucleos pienóticos, gigantes e vacuolizados, bem como núcleos com uma aparente descompactaçäo da cromatina do cromocentro foram detectados nos espécimes-teste. Admite-se que um decréscimo no número de núcleos a curto ou longo prazo após os choques de temperatura seja contribuído näo só pela degeneraçäo das células que apresentam núcleos vacuolizados e picnóticos, mas também por fusäo nuclear. Supöe-se que os núcleos gigantes, que apareceram com predominância nos espécimes submetidos ao choque hipertérmico e, ao mesmo tempo, a presença de hsp, desempenhem papel na manutençäo da sobrevivência do inseto nesta condiçäo experimental específica. Embora muitas das características nucleares encontradas nos espécimes submetidos aos choques de temperatura tenham sido também descritas após açäo de outros agentes estressantes, o choque hipertérmico foi o mais efetivo na promoçäo da aparente descompactaçäo da heterocromatina do crfomocentro. Com base nos tipos e frequências dos núcleos encontrados após choque hipertérmico e queda na sobrevivência do inseto sob tal circunstância, considera-se que, se existem substâncias crioprotetoras em T. infestans, estas näo seriam eficientes para proteger o inseto de um choque hipotérmico relativamente longo