RESUMO
Thiamethoxam is a neonicotinoid that has been used to control insect pests. The literature reports a few behavioral studies evaluating the toxic effect of thiamethoxam in ants; however, there are scarce studies at the cellular level. The present research evaluated the effects of thiamethoxam in labial (LG) and mandibular glands (MG), fat bodies (FB), and Malpighian tubules (MT) of workers of Atta sexdens, using transmission electron microscopy. The duct and secretory cells of LG were profoundly affected, then the production of saliva can be compromised, as well as its quality and subsequent use. In MG, reservoir and canaliculi cells presented slight alterations; however, MG secretory cells presented vacuoles containing lamellar structures, increased lipid production, and a large amount of mitochondria, which may lead to organ's malfunctioning. The FB cell alterations do not seem enough to cause significant changes that lead to cell death. Prominent changes in MT, such as loss of the electron-dense concentric ring, increased smooth endoplasmic reticulum, loss of basal infolds, vacuoles containing mineralized granules, and lamellar structures associated with mitochondria, suggest that their excretory function is compromised. In conclusion, thiamethoxam acts not only in the nervous system but also contributes to systemic toxicity on the target organism.
Assuntos
Formigas , Corpo Adiposo , Glândulas Salivares , Tiametoxam , Animais , Corpo Adiposo/efeitos dos fármacos , Corpo Adiposo/ultraestrutura , Inseticidas , Microscopia Eletrônica de Transmissão , Mitocôndrias , Saliva , Glândulas Salivares/efeitos dos fármacos , Glândulas Salivares/ultraestruturaRESUMO
The effects of biopesticides on insects can be demonstrated by morphological and ultrastructural tools in ecotoxicological analysis. Azadirachtin-based products are widely used as biopesticides, affecting numerous insect populations. Through morphological biomarkers, this study aimed to characterize the fat bodies of both the southern armyworm Spodoptera eridania and the predator Ceraeochrysa claveri after chronic exposure to azadirachtin. Larvae of S. eridania and C. claveri were fed with fresh purple lettuce leaves (Lactuca sativa) and egg clusters of Diatraea saccharalis treated with azadirachtin solution of 6 mg active ingredient (a.i.)/L and 18 mg a.i./L for 7 days, respectively. The biological data showed a significant reduction in survival and body mass in S. eridania and cytotoxic effects in the parietal and perivisceral fat bodies in both species. Ultrastructural cell damage was observed in the trophocytes of both species such as dilated cisternae of the rough endoplasmic reticulum and swollen mitochondria. Trophocytes of S. eridania and C. claveri of the parietal and perivisceral layers responded to those injuries by different cytoprotective and detoxification means such as an increase in the amount of cytoplasmic granules containing calcium, expression of heat shock protein (HSP)70/HSP90, and development of the smooth endoplasmic reticulum. Despite all the different means of cytoprotection and detoxification, they were not sufficient to recover from all the cellular damages. Azadirachtin exhibited an excellent performance for the control of S. eridania and a moderate selectivity for the predator C. claveri, which presents better biological and cytoprotective responses to chronic exposure to azadirachtin.
Assuntos
Corpo Adiposo/fisiologia , Limoninas/farmacologia , Neópteros/fisiologia , Controle Biológico de Vetores , Comportamento Predatório , Spodoptera/fisiologia , Animais , Bioensaio , Corpo Adiposo/citologia , Corpo Adiposo/efeitos dos fármacos , Corpo Adiposo/ultraestrutura , Larva/efeitos dos fármacos , Larva/ultraestrutura , Neópteros/efeitos dos fármacos , Neópteros/ultraestrutura , Spodoptera/efeitos dos fármacos , Spodoptera/ultraestruturaRESUMO
The fat body (FB) consists of two types of cells: throphocytes and oenocytes. Throphocytes are related to intermediary metabolism storing lipids, carbohydrates, and proteins while oenocytes play role in the lipids and lipoproteins production. The vitellogenin is the precursor of egg yolk (vitelline) and is synthesized on FB. The aim of this work was to analyze the effects of hormones acting in bee reproduction, as juvenile hormone (JH) and ecdisteroids (20 HE) on FB cells, where vitellogenin is synthesized. For the study were chose nurse workers that in Melipona quadrifasciata anthidioides present activated ovaries and produce eggs, and virgin queens whose ovaries are not yet activated, presenting only previtellogenic follicles. FB trophocytes from these classes of bees were cultivated in media containing different amounts of JH and 20-HE. The effects on trophocytes cytoplasm reserves of lipids, proteins, and activity of acid phosphatase were compared by observing preparations from cultured FB, treated and control, by transmission electron microscopy (TEM). The results showed that the hormones effects are related to the bee's caste and functional ovary stage. The role of acid phosphatase on mobilization of the trophocyte reserves was also determined.
Assuntos
Abelhas/efeitos dos fármacos , Ecdisterona/farmacologia , Corpo Adiposo/citologia , Sesquiterpenos/farmacologia , Animais , Abelhas/crescimento & desenvolvimento , Abelhas/metabolismo , Abelhas/ultraestrutura , Corpo Adiposo/efeitos dos fármacos , Corpo Adiposo/metabolismo , Corpo Adiposo/ultraestrutura , Feminino , Microscopia Eletrônica de Transmissão , Ovário/efeitos dos fármacos , Ovário/crescimento & desenvolvimento , Ovário/metabolismo , Ovário/ultraestrutura , Proteínas/metabolismo , Reprodução/efeitos dos fármacosRESUMO
Fat body cells or throphocytes of individuals during beginning of pupation (pre-pupae) of Apis mellifera were collected and studied by routine and cytochemical preparations for transmission electron microscopy (TEM). The results showed that the trophocytes present large reserves of lipids, proteins, and glycogen. Imidazole osmium treatment revealed that lipids are deposited as droplets in the cytoplasm and also within protein granules. Thiery's reaction showed the presence of glycogen inside protein granules. An acid phosphatase reaction was performed to verify the role of this enzyme in the mobilization of stored reserves during metamorphosis. Positive reaction for acid phosphatase was detected at larger protein granules, at the periphery of the large lipid droplets, and free in the cytoplasm. The contents of protein, lipid and glycogen are stored in the trophocytes at larval phase to be used during metamorphosis. The acid phosphatase present in the products stored might be responsible for their metabolization, while acid phosphatase free in cytoplasm might actuates in the trophocytes histolysis that occurs during metamorphosis for energy production.
Assuntos
Fosfatase Ácida/metabolismo , Abelhas/enzimologia , Abelhas/metabolismo , Corpo Adiposo/enzimologia , Corpo Adiposo/metabolismo , Animais , Abelhas/ultraestrutura , Grânulos Citoplasmáticos/metabolismo , Grânulos Citoplasmáticos/ultraestrutura , Corpo Adiposo/ultraestrutura , Glicogênio/metabolismo , Metabolismo dos Lipídeos , Microscopia Eletrônica de Transmissão , Proteínas/metabolismo , Pupa/metabolismoRESUMO
The insect fat body plays major roles in the intermediary metabolism, in the storage and transport of haemolymph compounds and in the innate immunity. Here, the overall structure of the fat body of five species of mosquitoes (Aedes albopictus, Aedes fluviatilis, Culex quinquefasciatus, Anopheles aquasalis and Anopheles darlingi) was compared through light, scanning and transmission electron microscopy. Generally for mosquitoes, the fat body consists of lobes projecting into the haemocoel and is formed by great cell masses consisting of trophocytes and oenocytes. Trophocytes are rich in lipid droplets and protein granules. Interestingly, brown pigment granules, likely ommochromes, were found exclusively in the trophocytes located within the thorax and near the dorsal integument of Anopheles, which is suggestive of the role these cells play in detoxification via ommochrome storage. This study provides a detailed comparative analysis of the fat body in five different mosquito species and represents a significant contribution towards the understanding of the structural-functional relationships associated with this organ.
Assuntos
Culicidae/anatomia & histologia , Corpo Adiposo/anatomia & histologia , Animais , Culicidae/ultraestrutura , Corpo Adiposo/ultraestrutura , Feminino , Masculino , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Especificidade da EspécieRESUMO
The insect fat body plays major roles in the intermediary metabolism, in the storage and transport of haemolymph compounds and in the innate immunity. Here, the overall structure of the fat body of five species of mosquitoes (Aedes albopictus, Aedes fluviatilis, Culex quinquefasciatus, Anopheles aquasalis and Anopheles darlingi) was compared through light, scanning and transmission electron microscopy. Generally for mosquitoes, the fat body consists of lobes projecting into the haemocoel and is formed by great cell masses consisting of trophocytes and oenocytes. Trophocytes are rich in lipid droplets and protein granules. Interestingly, brown pigment granules, likely ommochromes, were found exclusively in the trophocytes located within the thorax and near the dorsal integument of Anopheles, which is suggestive of the role these cells play in detoxification via ommochrome storage. This study provides a detailed comparative analysis of the fat body in five different mosquito species and represents a significant contribution towards the understanding of the structural-functional relationships associated with this organ.
Assuntos
Animais , Feminino , Masculino , Culicidae/anatomia & histologia , Corpo Adiposo/anatomia & histologia , Culicidae/ultraestrutura , Corpo Adiposo/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Especificidade da EspécieRESUMO
Morphological studies have been performed in invertebrates to elucidate cellular and/or tissue damage caused by environmental contamination. In present work, the exposure to industrial soil contaminated with polycyclic aromatic hydrocarbons and metals led to histological alterations in the midgut of Rhinocricus padbergi (Diplopoda). The following alterations were observed: increase of cytoplasmic granules in the fat body; increase in the number of regions of the epithelium in the process of renewal; increase in the number of hemocytes present among the cells of the fat body and degenerative changes in the midgut epithelium. Based on the results, we concluded that R. padbergi proved to be an excellent bioindicator for the evaluation of soil quality. The observed changes could be used as biomarkers for assessing sublethal effects of contaminated soils.
Assuntos
Artrópodes/efeitos dos fármacos , Monitoramento Ambiental/métodos , Trato Gastrointestinal/efeitos dos fármacos , Resíduos Industriais , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Poluentes do Solo/toxicidade , Animais , Artrópodes/metabolismo , Artrópodes/ultraestrutura , Biomarcadores/análise , Relação Dose-Resposta a Droga , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/ultraestrutura , Corpo Adiposo/efeitos dos fármacos , Corpo Adiposo/metabolismo , Corpo Adiposo/ultraestrutura , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/ultraestrutura , Hidrocarbonetos Policíclicos Aromáticos/farmacocinética , Medição de Risco/métodos , Poluentes do Solo/química , Poluentes do Solo/farmacocinética , Fatores de TempoRESUMO
During the process of Arthropoda reproduction, the synthesis and uptake of proteins, carbohydrates, and lipids by oocytes is termed vitellogenesis. These compounds that will make up the yolk may be in ticks endogenously synthesized by the oocytes and/or exogenously produced by the fat body and pedicel cells. This study examined the fat body of Amblyomma cajennense ticks at the cytochemical ultrastructural level to demonstrate the presence of lipids, proteins and carbohydrates in trophocytes. The lipids were detected in higher quantity than proteins and carbohydrates in the fat body cells, suggesting that the role of the fat body in tick is stored lipids and carbohydrates to convert them in energy, or still they could be used with cell structural purpose. The electrophoresis technique applied at A. cajennense fat body demonstrated specifically the molecular mass of proteins: about 98kDa. By the other hands, the fat body is not the organ responsible for the synthesis of the yolk protein, role probably performed by the pedicel cells.
Assuntos
Corpo Adiposo/citologia , Ixodidae/fisiologia , Vitelogênese/fisiologia , Animais , Carboidratos/análise , Eletroforese em Gel de Poliacrilamida , Corpo Adiposo/fisiologia , Corpo Adiposo/ultraestrutura , Feminino , Ixodidae/citologia , Lipídeos/análise , Microscopia Eletrônica de Transmissão , Peso Molecular , Proteínas/análise , Proteínas/químicaRESUMO
The fat body is the intermediary metabolism organ of insects and the main source of hemolymph components. In the current study, the microanatomy of Aedes aegypti (L., 1762) fat body was studied through scanning electron microscopy to observe the effects of blood feeding and aging. Three groups of female mosquitoes were used: newly emerged females, 18-d-old sugar-fed females, and 18-d-old blood-fed females. In Ae. aegypti, the fat body is located beneath the integument, and it is subdivided into dorsal, ventral, and lateral lobes, with the latter two being larger than the dorsal lobes. The lobes projected into the body cavity, and they were covered externally by a basal lamina with rounded cells beneath it. In 18-d-old sugar-fed females, the ventral and dorsal fat bodies seemed more developed than in newly emerged mosquitoes. The fat body hypertrophy caused by aging in the sugar-fed mosquito was probably associated with lipid accumulation due to the sugar diet. The blood-fed 18-d-old mosquitoes showed flattened fat bodies in all locations. The fat body modifications after the blood ingestion may be associated with midgut expansion after blood feeding, followed by ovary hypertrophy that mechanically compresses the fat body against the body wall. The structural changes in the fat body after a bloodmeal may be important for midgut extension to maximize blood storage and subsequent ovary enlargement, leading to the organ's reorganization in the body cavity. In addition, the depletion of fat body content during vitellogenesis could be responsible for the shrinking and flattening of the fat body lobes.
Assuntos
Aedes/ultraestrutura , Envelhecimento/fisiologia , Corpo Adiposo/ultraestrutura , Aedes/fisiologia , Animais , Corpo Adiposo/fisiologia , Comportamento Alimentar , Feminino , Microscopia Eletrônica de VarreduraRESUMO
The ultrastructural cytochemistry study and the chemical analysis carried out to examine the fat body of workers of the basal Attini Cyphomyrmex rimosus and Mycetarotes parallelus and the derived Acromyrmex disciger and Atta laevigata revealed very electrondense protein granules of varied sizes and shapes distributed throughout the cytoplasm of parietal and perivisceral trophocytes and oenocytes. Lipids were present in the cytoplasm of trophocytes as very electrondense granules. In M. parallelus, A. disciger, and A. laevigata, lipids were present as droplets. In parietal as well as perivisceral oenocytes, lipid granules were very electrondense. In A. laevigata, lipids were present as droplets. The chemical analysis using gas chromatography showed that the main lipid compounds present in trophocytes and oenocytes were saturated (myristic, palmitic, and stearic) and unsaturated fatty acids (oleic and linoleic). Also, in basal species, lipid compounds consisted of mainly saturated fatty acids, while in derived species saturated as well as unsaturated fatty acids were observed.
Assuntos
Formigas/química , Formigas/citologia , Corpo Adiposo/citologia , Hierarquia Social , Proteínas de Insetos/análise , Lipídeos/análise , Animais , Formigas/ultraestrutura , Corpo Adiposo/ultraestruturaRESUMO
The present ultramorphological, histological and ultrastructural study on the fat body of semi-engorged females of Amblyomma cajennense revealed that this tissue is diffuse and consists of strands of cells surrounding the tracheal trunks. Morphometric analysis showed that the cellular and nuclear areas of round-shaped trophocytes are larger than those of cuboidal trophocytes, indicating that the arrangement of the former provides more contact area with the haemolymph. In this species, the fat body is found right underneath the integument and around organs. It consists of two cell types that despite distinct morphological characteristics and locations in the tissue, present the same histological features. In this study, these cells were termed cuboidal trophocytes when arranged as strands of cells and present in larger numbers, and round-shaped trophocytes when lying on these strands and observed in fewer numbers. Histological observations revealed that both types of trophocytes have one nucleus in their cytoplasm and also exhibit numerous vacuoles of different sizes and contents. Ultrastructural examination revealed that the organelles more frequently observed were the vesicular and lamellar rough endoplasmic reticulum, and mitochondria with tubular crests, indicating that they might be involved in lipid synthesis. Smooth endoplasmic reticulum was not observed. Cuboidal trophocytes arranged in strands, despite being closely associated, do not exhibit fused plasma membranes. Rather, the fusion of basal lamina of two neighboring cells is occasionally observed, acting as a selective permeability barrier. Here, a new terminology for tick fat body is proposed. It is based on fat body location (parietal, when located right underneath the integument instead of peripheral; and perivisceral, when located around organs instead of central) terminologies previously suggest by Obenchain and Oliver and for the cells constituting them, cuboidal trophocytes when arranged as strands, and round-shaped trophocytes when lying on these strands. Nephrocytes were not observed in semi-engorged females of A. cajennense.
Assuntos
Ixodidae/ultraestrutura , Animais , Corpo Adiposo/citologia , Corpo Adiposo/ultraestrutura , Feminino , Ixodidae/citologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de TransmissãoRESUMO
The fat body cells of Pachycondyla (=Neoponera) villosa are disposed in a single layer between the cuticle and the digestive tract, forming a group of cells enclosed by a thin membrane. Histological studies have revealed three different cellular types: trophocyte (more abundant), urate, (located among the trophocytes), and oenocyte (the scarcest), usually observed laying near the cuticle. Histochemically, the trophocytes showed a positive reaction for basic proteins in the nucleus and cytoplasm, as well as a strong positive reaction in the cytoplasmic granules. The test for carbohydrates showed a strong positive reaction throughout the cytoplasm, while the test for lipids was positive for the cytoplasmic vesicles. The urate cells showed a positive reaction for basic proteins in the nucleus and in the areas of the cytoplasm surrounding the vesicles. These cells did not react to the PAS test or to Sudan Black B. The oenocytes showed a weak positive reaction to PAS and a strong positive reaction to Sudan Black B and Mercuric-bromophenol Blue.
Assuntos
Formigas/ultraestrutura , Carboidratos/análise , Corpo Adiposo/ultraestrutura , Proteínas de Insetos/análise , Lipídeos/análise , Animais , Formigas/química , Corpo Adiposo/química , Histocitoquímica , Larva/química , Larva/ultraestruturaRESUMO
It is already known that the behaviour of the honeybee Apis mellifera is influenced by the Earth's magnetic field. Recently it has been proposed that iron-rich granules found inside the fat body cells of this honeybee had small magnetite crystals that were responsible for this behaviour. In the present work, we studied the iron containing granules from queens of two species of honeybees (A. mellifera and Scaptotrigona postica) by electron microscopy methods in order to clarify this point. The granules were found inside rough endoplasmic reticulum cisternae. Energy dispersive X-ray analysis of granules from A. mellifera showed the presence of iron, phosphorus and calcium. The same analysis performed on the granules of S. postica also indicated the presence of these elements along with the additional element magnesium. The granules of A. mellifera were composed of apoferritin-like particles in the periphery while in the core, clusters of organised particles resembling holoferritin were seen. The larger and more mineralised granules of S. postica presented structures resembling ferritin cores in the periphery, and smaller electron dense particles inside the bulk. Electron spectroscopic images of the granules from A. mellifera showed that iron, oxygen and phosphorus were co-localised in the ferritin-like deposits. These results indicate that the iron-rich granules of these honeybees are formed by accumulation of ferritin and its degraded forms together with elements present inside the rough endoplasmic reticulum, such as phosphorus, calcium and magnesium. It is suggested that the high level of phosphate in the milieu would prevent the crystallisation of iron oxides in these structures, making very unlikely their participation in magnetoreception mechanisms. They are most probably involved in iron homeostasis.
Assuntos
Abelhas/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Corpo Adiposo/ultraestrutura , Ferritinas/metabolismo , Ferro/metabolismo , Animais , Abelhas/metabolismo , Grânulos Citoplasmáticos/metabolismo , Microscopia Eletrônica/métodosRESUMO
The fat body of the diplopod Rhinocricus padbergi is located in two preferential areas of its body: a) immediately below the tegument, denominated parietal, and b) filling the body cavity, close to the viscera, mainly the ovaries and alimentary canal, denominated perivisceral. Ultrastructurally, its cells, the adipocytes, presented varied morphology and contained organelles indicating that they are cells that mainly produce and store lipids and proteins. The presence of cells similar to the oenocytes found in insects was observed for the first time in diplopods, associated to the fat body of R. padbergi. Our observations suggest that this tissue probably maintains activity cycles, since the presence of cells undergoing apoptosis was detected.
Assuntos
Artrópodes/ultraestrutura , Corpo Adiposo/ultraestrutura , Animais , Artrópodes/citologiaRESUMO
The fat body of the diplopod Rhinocricus padbergi is located in two preferential areas of its body: a) immediately below the tegument, denominated parietal, and b) filling the body cavity, close to the viscera, mainly the ovaries and alimentary canal, denominated perivisceral. Ultrastructurally, its cells, the adipocytes, presented varied morphology and contained organelles indicating that they are cells that mainly produce and store lipids and proteins. The presence of cells similar to the oenocytes found in insects was observed for the first time in diplopods, associated to the fat body of R. padbergi. Our observations suggest that this tissue probably maintains activity cycles, since the presence of cells undergoing apoptosis was detected.(AU)
Assuntos
Animais , RESEARCH SUPPORT, NON-U.S. GOVT , Artrópodes/ultraestrutura , Corpo Adiposo/ultraestrutura , Artrópodes/citologiaRESUMO
The effects of food intake and carbohydrate administration on fatty acid delta9-desaturation were investigated in isolated microsomes from Triatoma infestans fat body. Fifth instar nymphs, which were solely blood-fed just after the molt and then fasted, were used as controls and for determination of optimal assay conditions. Both [1-14C]palmitic and [1-14C]stearic acids in a medium containing ATP, CoA, MgCl2, NADH, NaF, and O2 were tested. For the control group, optimal conditions were a pH of 6.8-7.2, an incubation temperature of 29 degrees C, and an incubation time of 10 min. delta9-Desaturation depended on the presence of reduced pyridine dinucleotides; NADH and NADPH were equally efficient. Stearic acid showed a higher apparent Vmax than palmitic acid, but the apparent Km were very similar. When fifth instar nymphs were blood-fed weekly, a marked increase of delta9-desaturation was observed for both acids. Higher desaturation activity was also induced by injection of the carbohydrate trehalose into the hemolymph of fasted nymphs. These results indicate that insect delta9-desaturation, like the mammalian counterpart, is sensitive to dietary changes and carbohydrate administration.