Ação do inseticida análogo ao hormônio juvenil Piriproxifeno em larvas de Apis mellifera: estudos morfológicos aplicados a ecotoxicologia

As abelhas são vítimas do uso de inseticidas para combater insetos praga nos agroecossistemas. Apis mellifera, a espécie mais conhecida devido ao seu valor econômico, apresenta voos de grande alcance e, devido à sua estreita relação com a flora e o fato de possuir o corpo coberto por pelos que coletam várias partículas presentes no ambiente, essa espécie de abelha pode ser utilizada para a detecção de resíduos de pesticidas em plantas. Embora haja trabalhos relatando a capacidade de tolerância das abelhas adultas a determinados inseticidas, há falta de dados sobre efeitos subletais, os quais podem estar relacionados ao distúrbio do colapso das colônias, conhecido como CCD. Dentro dos dados existentes, poucos são relacionados às larvas e pupas, indiretamente contaminadas durante a alimentação larval, no caso de Apis melífera. Assim, o objetivo do presente projeto é avaliar a ação de um inseticida análogo ao hormônio juvenil (piriproxifeno) na Concentração Máxima Permitida no Campo (MFRC ) em diferentes proporções dessa concentração (MFRC/2, MFRCx2 e MFRCx5) em glândulas salivares larvais, discos imaginas e corpo gorduroso de Apis mellifera, em condições laboratoriais, por meio de análises morfológicas. Nas glândulas de seda, a MFRC e MFRC/2 não apresentaram características diferentes do grupo controle. Com o dobro da MRFC, observaram-se alterações morfológicas no epitélio secretor em relação ao tamanho das células que foi intenso em resposta ao aumento da concentração de piriproxifeno, indicando alta taxa de endopoliploidia e intensificação da produção de secreção, o que explica a seda só ter sido observada nos grupos experimentais tratados com piriproxifeno, nas dosagens não permitidas. As células do corpo gorduroso também apresentaram tamanho maior nas larvas tratadas com o dobro da MRFC. Embora no corpo gorduroso parietal não tenha ocorrido alterações morfológicas nos trofócitos em resposta à exposição crônica ao piriproxifeno, o corpo gorduroso perivisceral apresentou núcleos com morfologia alterada nos tratamentos com o inseticida, exceto no grupo experimental tratado com metade da MRFC. Os núcleos alterados podem ser um indicativo de início do processo de morte celular programada, o que possivelmente pode ter ocorrido em resposta `a intensificação dos processos metabólicos envolvidos na função de desintoxicação exercida por essas células. Além disso, na concentração mais alta, foram encontrados trofócitos binucleados em grande quantidade, o que também sugere a intensificação dos processos de desintoxicação da larva. As alterações presentes, embora possam ser sutis, podem resultar em anomalias na formação dos ´órgãos do adulto. Dessa forma, são necessárias mais pesquisas para obter dados adicionais como a emergência dos adultos e sua viabilidade.Fil: Machado de Souza, Tatiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones En Recursos Naturales, Agroecología y Desarrollo Rural. - Universidad Nacional de Rio Negro. Instituto de Investigaciones En Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Universidade Federal do São Carlos; BrasilFil: Rodrigues, Barbara Nobrega. Universidade Federal do São Carlos; BrasilFil: Andrade Dantas,Talita de. Universidade Federal do São Carlos; BrasilFil: Malaspina, O.. Universidade Federal do São Carlos; BrasilFil: Silva Zacarin, Elaine Cristina Mathias da. Universidade Federal do São Carlos; BrasilIX Congresso de Ecologia do BrasilSão LourençoBrasilSociedade de Ecologia do Brasi

Effects of larval exposure to the fungicide pyraclostrobin on the post-embryonic development of Africanized Apis mellifera workers

Among the more than twenty thousand bee species currently described, Apis mellifera stands out for its high economic relevance due to crop pollination. In recent decades, many studies have registered a decline in bee populations associating multiple factors, including pesticides. These molecules can arrive through residues present in the nectar and pollen, which can be ingested by the larvae. However, studies that contemplate the effects of fungicides on larvae and adults are rare. Thus, the objective of the study was to evaluate the effects of the exposure to pyraclostrobin in the larval phase and verify the late effects in newly emerged bees. The larvae were subjected to repeated exposure (third to the sixth day of the bioassay). The concentrations of pyraclostrobin consumption were 127.58 ng/larva (PT1), 13.16 ng/larva (PT2), and 4.24 ng/larva (PT3), both based on residues found in the field like as pollen and bee bread. The effects on larval mortality, pupation, emergence and survival rates, and median lethal time of newly emerged worker bees were evaluated. We also evaluated cell death and chitin marking of the peritrophic matrix in the intestine of larvae and newly emerged bees. No adverse effects were observed on the post-embryonic development of the larvae and survival time of the newly emerged workers, showing tolerance to the fungicide. However, the intestine epithelium of larvae (PT1 and PT2) and adults (PT1) showed immunostaining for cell death and increased intensity of chitin marking in the peritrophic matrix, indicating a late effect of the pyraclostrobin fungicide. Thus, the ingestion of the fungicide in the larval stage can impair the bee development and the health and performance of the colony. In this perspective, studies that consider the effects of fungicides in the different stages of bee development are crucial for a better interpretation of the risks of exposure

Immunodetection of heat shock protein 70 and cell death in liver of a neotropical fish acutely and chronically exposed to acetaminophen and propranolol

The use of pharmaceutical drugs ends frequently in their inappropriate disposal and treatment at waste water treatment plants, which is the cause of their widespread presence in the environment. Yet, there is limited understanding or knowledge of their effects to non-target aquatic organisms. The drugs acetaminophen (analgesic and antipyretic) and propranolol (β-blocker) are widely found in the aquatic environment, where they can interact with non-target exposed organisms, causing adverse effects. Heat shock proteins (namely HSP70) are molecular chaperones which help to refold misfolded cellular proteins, and the increase in their in vivo levels indicates a change in the cell to counteract the proteotoxic effects of the triggered stress, namely which is consequent to exposure to toxicants. The objective of this study was to quantify the levels of liver HSP70 proteins in individuals of the neotropical fish species Phalloceros harpagos, acutely and chronically exposed to concentrations of acetaminophen and propranolol, in the range of those already determined to occur in the wild. Fish acutely exposed to acetaminophen (concentrations of 8, 80, 800, and 8000 μg L-1) and to propranolol (levels of 1, 10, and 1000 μg L-1) evidenced increased intensity of HSP70 immunolabeling in liver cells. Similarly, animals chronically exposed to propranolol, at concentrations of 0.0625, 0.125, 0.25, and 0.5 μg L-1, showed a comparable trend. This finding suggests the triggering of a cytoprotective effect that was effective in preventing cell death in exposed groups in relation to the control group. In contrast, chronic exposure to acetaminophen caused a decrease in HSP70 labeling intensity in fish hepatocytes (animals exposed to 5, 10, 20, 40, and 80 μg L-1), with no induction of DNA fragmentation in the nuclei of hepatocytes of these fish. Some of the hepatic HSP70 responses observed in this study were obtained at levels already reported to occur in the wild. Finally, this study showed how levels of acetaminophen at microliter concentration can exert side effects on non-target organisms after chronic exposure, suggesting that environmentally exposed organisms may be subjected to adverse conditions that modify the typical response pattern of HSP70 levels.publishe

Cellular responses in the Malpighian tubules of Scaptotrigona postica (Latreille, 1807) exposed to low doses of fipronil and boric acid

Studies of sub-lethal effects of pesticide residues on stingless bees are scarce and morphological analysis of organs would add information to toxicological analysis in order to clarify the continuous exposure of Scaptotrigona postica to insecticides. The aim of this study was to evaluate the morphology and histochemistry of the Malpighian tubules (excretory organ) of S. postica exposed to fipronil or boric acid to detect cellular responses that indicate toxicity or adaptative mechanisms to stress induced by exposure of worker bees to low doses of these chemical compounds. Newly emerged bees were submitted to toxicological bioassays and morphological analyses by optical microscopy and Transmission Electron Microscopy, as well as histochemical methods, were performed to detect proteins and glycoconjugates. Additionally, immunohistochemical detection of DNA fragmentation and HSP70 (70-kDa Heat shock protein) were performed to detect cell death and stress response, respectively. Statistical analysis, for the bioassays conducted with ingestion of contaminated diet with boric acid at 0.75% (w/w) or with fipronil at 0.1μg/kg of food, showed that the survival of bees that ingested the contaminated diets were significantly different to the survival rate presented by the control group (P<0.0001). Although some characteristics indicative of initiation of cell death were observed, the cells remained metabolically active in the processes of excretion and inactivation of chemical compounds. The data from this study reinforce the importance of research on sublethal effects of low doses of pesticides on bees in an attempt to assess a possible realistic dose and evaluate the risk assessment of stingless bee S. postica foraging in the vicinity of cultivated fields and/or in green urban areas. © 2013 Elsevier Ltd

Sperm quality in adult male rats exposed to cadmium in utero and lactation

Recent studies indicate that several anomalies of the male reproductive system may be produced by acute or chronic exposure to chemical substances released into the environment, attributed to increased industrial development. Among these substances are trace metals such as cadmium (Cd). The aim of this study was to assess reproductive parameters in adult male rats whose mothers were exposed to Cd during pregnancy and lactation. For this, pregnant rats were divided into two experimental groups: treated rats, which received ad libitum cadmium acetate (CdAc) solution in distilled water (10 mg Cd/L), and control rats, which received sodium acetate (NaAc) solution in distilled water (equimolar to the CdAc). The results showed that the exposure to Cd in utero and through lactation adversely affected sperm quality of adult rats, as evidenced by compromised sperm morphology and motility and increased rate of cell death in testis7516-1710471058CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2009/02044-

SPERM QUALITY IN ADULT MALE RATS EXPOSED TO CADMIUM IN UTERO AND LACTATION

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Recent studies indicate that several anomalies of the male reproductive system may be produced by acute or chronic exposure to chemical substances released into the environment, attributed to increased industrial development. Among these substances are trace metals such as cadmium (Cd). The aim of this study was to assess reproductive parameters in adult male rats whose mothers were exposed to Cd during pregnancy and lactation. For this, pregnant rats were divided into two experimental groups: treated rats, which received ad libitum cadmium acetate (CdAc) solution in distilled water (10 mg Cd/L), and control rats, which received sodium acetate (NaAc) solution in distilled water (equimolar to the CdAc). The results showed that the exposure to Cd in utero and through lactation adversely affected sperm quality of adult rats, as evidenced by compromised sperm morphology and motility and increased rate of cell death in testis.7516-1710471058Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

SPERM QUALITY IN ADULT MALE RATS EXPOSED TO CADMIUM IN UTERO and LACTATION

Recent studies indicate that several anomalies of the male reproductive system may be produced by acute or chronic exposure to chemical substances released into the environment, attributed to increased industrial development. Among these substances are trace metals such as cadmium (Cd). The aim of this study was to assess reproductive parameters in adult male rats whose mothers were exposed to Cd during pregnancy and lactation. For this, pregnant rats were divided into two experimental groups: treated rats, which received ad libitum cadmium acetate (CdAc) solution in distilled water (10 mg Cd/L), and control rats, which received sodium acetate (NaAc) solution in distilled water (equimolar to the CdAc). The results showed that the exposure to Cd in utero and through lactation adversely affected sperm quality of adult rats, as evidenced by compromised sperm morphology and motility and increased rate of cell death in testis.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Cardiac Adaptations Of Bullfrog Tadpoles In Response To Chytrid Infection.

The chytrid fungus Batrachochytrium dendrobatidis (Bd) can result in heart failure in Bd-susceptible species. Since Bd infection generally does not cause mortality in North American bullfrogs, the aim of this work was to verify whether this species presents any cardiac adaptation that could improve the tolerance to the fungus. Thus, we analyzed tadpoles' activity level, relative ventricular mass, ventricle morphology, in loco heart frequency, and in vitro cardiac function. The results indicate that infected animals present an increase in both ventricular relative mass and in myofibrils' incidence, which accompanied the increase in myocytes' diameter. Such morphological alterations enabled an increase in the in vitro twitch force that, in vivo, would result in elevation of the cardiac stroke volume. This response requires much less energy expenditure than an elevation in heart frequency, but still enables the heart to pump a higher volume of blood per minute (i.e., an increase in cardiac output). As a consequence, the energy saved in the regulation of the cardiac function of Bd-infected tadpoles can be employed in other homeostatic adjustments to avoid the lethal effect of the fungus. Whether other species present this ability, and to what extent, remains uncertain, but such possible interspecific variability might explain different mortality rates among different species of Bd-infected amphibians.323487-49