Baccharis dracunculifolia (Asteraceae) essential oil toxicity to Culex quinquefasciatus (Culicidae).

The control of mosquitoes by means of chemical insecticides has been a problem, mainly due to the possibility of resistance developed by insects to xenobiotics. For this reason, demand for botanical insecticides has increased. In this sense, the present work aims to verify the susceptibility and morphological and biochemical alterations of Culex quinquefasciatus larvae after exposure to essential oil (EO) of leaves of Baccharis dracunculifolia. To observe the larvicidal action, larvae were exposed to EO at concentrations of 25, 50, 100, and 200 mg/L, until their emergence to adults. The control group was exposed to deionized water and dimethyl sulfoxide. Morphological analyses were also carried out using hematoxylin and eosin, mercury bromophenol blue, Nile blue, and periodic acid Schiff. Biochemical analyses of total glucose, triacylglyceride (TAG), protein, and acetylcholinesterase levels were performed. The phytochemical analysis of the EO showed (E)-nerolidol as the major compound (30.62%). Larvae susceptibility results showed a LC50 of 34.45 mg/L for EO. Morphological analysis showed that there were histological changes in midgut. For biochemical analyses, the glucose level in the larvae exposed to EO for 24 h decreased significantly, unlike the TAG levels, which increased. The total protein level of the larvae also increased after exposure for 24 h, and acetylcholinesterase levels decreased significantly. Taking all our data into account, we can conclude that EO causes destabilization in larva, leading to histological changes, metabolic deregulation and, consequently, their death.

Ultrastructural alterations in colon absorptive cells of alloxan-induced diabetic rats submitted to long-term physical training.

Absorptive cells have notable importance for proper function of the colon, absorbing water and nutrients. In type I diabetes, hyperglycemia leads to remarkable alterations in cell structure. In absorptive cells, such changes may impair the function of the organ as a whole. Also, the effects of physical training, which plays crucial role in the treatment of diabetes, are not yet known in these cells. For this reason, to analyze the changes in colon epithelial absorptive cells of diabetic rats and the effects of physical training, Wistar rats were divided into four groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD), and trained diabetic (TD). The training protocol consisted of swimming for 60 min a day, 5 days per week, during 8 weeks. Colon samples were collected, processed, and evaluated by histochemical and ultrastructural techniques. Although histochemical analysis did not reveal major differences, significant morphological differences were ultrastructurally observed among groups, especially related to the structure of tight junctions, interdigitations, and microvilli, which became longer in diabetics, and whose length was reduced after physical training, as proved by statistical analysis. There were no relevant changes in organelles. Thus, the development of type I diabetes can lead to changes at ultrastructural level that, even subtle, may cause important alterations in cell function. The practice of physical training, in turn, proved to be an important ally in the treatment of such changes. However, it cannot be used singly for treating this disease, requiring the combined practice of other methods.

Ultra-structure and histochemistry of digestive cells of Podisus nigrispinus (Hemiptera: Pentatomidae) fed with prey reared on bt-cotton.

The toxic effects of Bt proteins from the body of the prey/host to predators and parasitoids have been investigated as a route of impact on non-target insects of Bt crops. This research aimed to analyze ultrastructural changes and histochemistry in digestive cells of the middle region of the midgut of Podisus nigrispinus fed, since its second instar, with Spodoptera frugiperda reared on Bt cotton variety Acala90 B, which expresses the toxin Cry 1Ac, and its non-Bt isoline Acala 90. Fragments of the midgut of P. nigrispinus were analyzed by electron microscopy. For the histochemical analysis, Bromophenol Blue, Periodic Acid Schiff von Kossa, Alcian Blue pH 2.5 and Sudan Black were used. The Cry1Ac toxin of Bt cotton ingested by S. frugiperda promotes a disorganization in the perimicrovillar matrix of P. nigrispinus (third trophic level), thus generating ultrastructural changes in the digestive cells, as elongation of microvilli, presence of spherocrystals and granules of different electron densities, in addition to altering the distribution pattern of glycogen, lipids and calcium of these cells in the median region of the midgut. Thus, we conclude that species moderately susceptible to Cry1Ac toxin, such as S. frugiperda, can acquire this toxin and expose it to P. nigrispinus, which can interfere with your ability to predation.

Morphology and protein content of hepatocytes in type I diabetic rats submitted to physical exercises.

The importance of physical exercise practice in the treatment of diabetes has been reported in many studies recently, but only limited data can be found regarding its benefits on liver morphology and protein content of hepatocytes. In order to assess the changes arising from the development of type I diabetes and the benefits of a training protocol, Wistar rats were divided into four groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD) and trained diabetic (TD). The training protocol consisted of swimming for 60 min a day, 5 days/week, during 8 weeks. Liver samples were collected, processed and analyzed by histochemical and ultrastructural techniques. Biochemical tests were also conducted to examine the protein content and quantity of DNA in the liver. In morphological assessment, the presence of areas of cytoplasmic basophilia observed in control subjects was not visualized in sedentary diabetics. It was related to differences in the amount of mitochondria in the cytosol. The mitochondrial structure has not undergone relevant changes, and the number of rough endoplasmic reticulum cisterns was clearly inferior in sedentary diabetics, suggesting lower protein production. However, the biochemical analysis of protein content indicated no statistical differences between groups. The exercise, in turn, was not responsible for major changes in these characteristics. On the whole, the morphological damages arising from type I diabetes were noteworthy. Nevertheless, regular physical training was not responsible for significant improvements in some respects, making evident the need for combined application of a distinct form of treatment.

Macromolecular array patterns of silk gland secretion in social Hymenoptera larvae.

The cocoon, produced by most holometabolous insects, is built with silk that is usually produced by the larval salivary gland. Although this silk has been widely studied in the Lepidoptera, its composition and macromolecular arrangement remains unknown in the Hymenoptera. The macromolecular array patterns of the silk in the larval salivary gland of some meliponids, wasps, and ants were analyzed with polarized-light microscopy, and they were compared with those of Bombyx mori (Lepidoptera). There is a birefringent secretion in the glandular lumen of all larvae, due to filamentous structural proteins that display anisotropy. The silk in the distal, middle and proximal regions of the secretory portion of Formicidae and Vespidae glands presented a lattice optical pattern. We found a different pattern in the middle secretory portion of the Meliponini, with a zigzag rather than a lattice pattern. This indicates that the biopolymer fibers begin their macromolecular reorganization at this glandular region, different from the Formicidae and the Vespidae, in which the zigzag optical pattern was only found at the lateral duct. Probably, the mechanism of silk production in the Hymenoptera is a characteristic inherited from a common ancestor of Vespoidea and Sphecoidea; the alterations in the pattern observed in the Meliponini could be a derived characteristic in the Hymenoptera. We found no similarity in the macromolecular reorganization patterns of the silk between the Hymenoptera species and the silkworm.

Comparative analysis of morphological, structural and morphometric patterns of Polistes versicolor (Olivier) (Hymenoptera: Vespidae) hypopharyngeal glands / Análise comparada do padrão morfológico, estrutural e morfométrico das glândulas hipofaríngeas de Polistes versicolor (Olivier) (Hymenoptera: Vespidae)

O presente estudo descreve, por meio de técnicas de histologia e ultramorfologia, os padrões morfológico e estrutural das glândulas hipofaríngeas de Polistes versicolor (Olivier), comparando-os aos de outros grupos de Hymenoptera. Além disso, analisa a presença de variações intraespecíficas dessas glândulas por meio de análises morfométricas das células secretoras de vespas em diferentes idades. Na espécie estudada foi constatada a presença de glândulas com características primitivas, possuindo células secretoras que desembocam individualmente na placa hipofaríngea. O padrão morfológico encontrado nas glândulas hipofaríngeas foi basicamente o mesmo para todas asvespas estudadas, entretanto o comprimento das células glandulares apresentou variações significativasentre indivíduos. Aparentemente essas variações não estão relacionadas com a idade.

Using ultramorphological and histochemical techniques, this study describes the structural and morphological patterns of Polistes versicolor (Olivier) hypopharyngeal glands, comparing them with patterns of other Hymenopteran groups. Besides, the presence of intra-specific variation was evidenced by morphometric analysis of the secretory cells in wasps with different ages. The studied species presented glands with primitive characteristics, with secretory cells discharging individually in the hypopharyngeal plate. The morphological pattern found in hypopharyngeal glands was basicallythe same for all studied wasps, however, the length of glandular cells showed significant variations between individuals. Apparently these variations are not related with age.

Metapleural- and postpharyngeal-gland secretions from workers of the ants Solenopsis invicta and S. geminata.

Chemical analyses by GC-MS of the metapleural glands (MG) from workers of Solenopsis invicta and S. geminata revealed for the first time the chemical composition of these glands and showed small differences between the two species. The MG of both species contain oleic, stearic, linoleic, and palmitic acid. Both ants, in addition, have small but significant amounts of hydrocarbons in their MG reservoir, which are the same as those found in their postpharyngeal glands (PPG). The PPG of both species contain alkanes, alkenes, and Me-branched alkanes. Each species is characterized by a specific composition of PPG chemicals with some overlap between species. These results suggest that the MG synthesizes mainly palmitic, linoleic, oleic, and stearic acids in these two ants, whereas PPG contains hydrocarbon mixes that widely vary between these two phylogenetically related species.

Ultramorphology and histology of the larval salivary gland of Pachycondyla villosa (Fabricius) (Hymenoptera: Formicidae, Ponerinae) / Utramorfologia e histologia da glândula salivar larval de Pachycondyla villosa (Fabricius) (Hymenoptera: Formicidae, Ponerinae)

The salivary gland possesses a single anterior duct with a columnar epithelium, two lateral ducts with simple cubical epithelium, which becomes columnar in the proximal portion, and two thin-walled reservoirs, from which two secretory regions arise. The dorsal and ventral branches of the secretory regions are connected via transverse commissures and ends in a loop. The secretory region is uniform and consists on a simple cubical epithelium. This paper also presents a review on the morphology of the salivary glands in insects, mainly in Hymenoptera-Aculeata.

A glândula salivar apresenta-se com um duto anterior único, formado por um epitélio colunar, dois dutos laterais curtos, os quais apresentam-se com epitélio cúbico simples e que na sua porção mais proximal torna-se colunar. Posterior a estes, encontram-se os dois reservatórios, os quais possuem o epitélio bastante delgado e é neste reservatório que a região secretora da glândula se abre. Os ramos dorsal e ventral da região secretora da glândula conectam-se por meio de comissuras transversais, sendo que, posteriormente, a região secretora termina em forma de "alça". A região secretora é uniforme, não apresenta tipos celulares distintos e é formada por um epitélio cúbico simples. Neste trabalho é apresentada, também, a revisão sobre a morfologia da glândula salivar larval em insetos, principalmente com relação aos Hymenoptera-Aculeata.