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 LC
50
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.
Sperm and spermatophore production in Callinectes danae Smith, 1869 were examined by histochemistry and correlated with gonadosomatic (GSI) and hepatosomatic (HSI) indices. The GSI from developing ...(DE) and mature (MAT) males increased while the HSI decreased from DE to MAT, demonstrating that the maturation of the male reproductive system requires resources from the hepatopancreas. No histological or histochemical differences were observed between DE and MAT except for the larger amount of secretions produced in MAT. Spermatogenesis occurs in the seminiferous lobules surrounded by accessory cells. Each lobule is filled with cells at the same developmental stage. Spermatid maturation is characterized by an increase in the metachromatic acrosome. Sperm are released into seminiferous ducts, which moves them to the vas deferens divided into anterior (AVD), median (MVD), and posterior (PVD) regions. Spermatophore formation begins at the anterior part of AVD; sperm masses are separated and compacted in small packets by a basophilic and alcianophilic secretion. Small amounts of eosinophilic secretion, positive for proteins and neutral polysaccharides, are added around the sperm initiating the formation of the spermatophore wall. Mature round spermatophores are found in the posterior part of AVD and present a thick glycoproteinaceous wall, surrounded by acidic polysaccharides. The spermatophores are stored in MVD without size difference from DE to MAT. The MVD is filled with a granular secretion composed of glycoproteins. The secretion in PVD is fluid and homogeneous, facilitating the transference of the spermatophores. In conclusion, the hepatopancreas is related to the maturation of the male reproductive system in C. danae. DE males presented all histological conditions to fertilize females as MAT males, but the decrease in HSI and increase in GSI indices correlated with the vas deferens indicate that reserves are necessary to produce large amounts of seminal fluid in MAT males.
Zara, F.J., Gaeta, H.H., Costa, T.M., Toyama, M.H. and Caetano, F.H. 2011. The ovarian cycle histochemistry and its relationship with hepatopancreas weight in the blue crab Callinectes danae ...(Crustacea: Portunidae). —Acta Zoologica (Stockholm) 00:1–13.
Several studies use macroscopic patterns of the ovarian development in crustaceans. Here, we examined the relationship between ovary histochemistry, changes in gonadosomatic and hepatosomatic indices against the macroscopic pattern of the ovarian development in Callinectes danae. Animals were collected in the south coast of São Paulo State, Brazil. Ovaries were macroscopically classified as juvenile, rudimentary, developing, intermediary, mature, and rudimentary ovigerous. Samples were fixed in 4% paraformaldehyde, processed for historesin, and stained with HE, protein, and neutral and acid polysaccharides detection. The juvenile oocytes are not enclosed by follicular cells and have fewer yolk nuclei being less intense in PAS reactivity than rudimentary oocytes. Developing oocytes show yolk granules and thick follicular cells. Yolk granules were positive for proteins and neutral polysaccharides. The intermediary stage is marked by a qualitative increase in yolk granules and the onset of chorion formation. In mature oocytes, cytoplasm is completely filled by yolk granules and the chorion is completely formed. Ovigerous ovaries have several atretic follicles and large quantities of hemocytes in the process of tissue reorganization. In C. danae, the changes in cell, goandosomatic and hepatosomatic indices coinciding with macroscopic observations and any combination of different macroscopic stages in a single pattern should be avoided.
► We analyzed the ultrastructure and histochemistry of the digestive cells of
Podisus nigrispinus fed
Spodoptera frugiperda reared on transgenic cotton. ► The results showed ultrastructural changes ...in the digestive cells, and modification in the distribution pattern of lipids, glycogen and calcium in these cells.
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.
Parasitoids have evolved mechanisms to evade their hosts' defenses. Bracon vulgaris (Ashmead) is a larval ectoparasitoid responsible for natural reduction of Anthonomus grandis (Boheman) and ...Pectinophora gossypiella (Saunders), which are considered the main cotton pests in the cotton agro-ecosystem in northeastern Brazil. This study aimed to analyze the sensory structures (antennae and ovipositor) involved in the parasitism behavior of B. vulgaris, and to describe and evaluate associations between composition, morphology, and functions of these structures in the parasitoid-host interaction. Results showed that the B. vulgaris ovipositor is a multifunctional structure of 2.7 ± 0.3 mm in length composed of 3 valves. Valves 1 and 2 are elongated, rigid, and act jointly to pierce the host's cuticle, to inject the poison glands secretion, and to deposit eggs. Valve 3 covers the other valves, giving them protection. Valve 3 also presents annulations in all its extension, which gives flexibility to the ovipositor, and trichoid sensilla that possibly capture vibrations from the host's feeding and locomotion, thereby aiding the parasite in the host selection. The presence of cuticular microtrichia was possibly responsible for the cleaning of the ovipositor, keeping it functional between the various insertions that occur during the parasitism behavior. The parasitoid's antennae are filliform-like, measure about 2 mm, and are composed of four types of sensilla (trichoids, basiconical, coeloconical, and placodes) that act as olfactory and gustatory receptors and/or express tactile, thermo,- and hygroreception functions. The integrated action of these sensory components corroborates the successful parasitism behavior of the parasitoid B. vulgaris.
•The addition of DPI can improve the degree of conversion under low irradiances.•DPI resins had higher polymerization stress, regardless the radiant exposure.•Better chemical/mechanical properties ...are observed at DPI resins.
The use of resin cements in clinical practice entails photopolymerization through prosthetic devices, which precludes light penetration. The objective of this study was to modify experimental resin cements (ERCs) with diphenyliodonium hexafluorophosphate (DPI) in an attempt to improve chemical and mechanical properties of materials cured with reduced irradiance and final radiant exposure.
A co-monomer base containing a 1:1 mass ratio of 2.2-bis4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) was prepared, with 1mol% of camphorquinone and 2mol% of ethyl 4-(dimethylamino)benzoate as initiator system. The resin was divided into 4 fractions according to the DPI concentrations (0, 0.5, 1 and 2mol%). The challenging polymerization condition was simulated performing the light activation (12, 23 and 46s) through a ceramic block (3mm thick). The irradiance was assessed with a calibrated spectrometer (1320mW/cm2), resulting in three levels of radiant exposure (0.58, 1.1 and 2.2J/cm2). The polymerization kinetics was evaluated in real-time using a spectrometer (Near-IR). Water sorption and solubility was analyzed and the cohesive strength of resins obtained through the microtensile test. Polymerization stress was assessed by Bioman method.
Resins containing DPI had higher degree of conversion and rate of polymerization than the control (without DPI). The use of DPI reduced water sorption and solubility, and led to higher cohesive strength compared to resins without the iodonium salt. However, the stress of polymerization was higher for experimental resins with DPI.
Even under remarkably reduced irradiance, cements containing a ternary initiating system with an iodonium salt can present an optimal degree of conversion and chemical/mechanical properties.
Pymetrozine represents a class of compounds for the control of sucking insects. However, chewing insects have also shown sensitivity to this compound. Therefore, although pymetrozine has been ...demonstrated to have a direct action on sucking insects, it could also affect species like the boll worm Anthonomus grandis by promoting histological changes in the intestine and alterations in biochemical parameters such as glycogen, lipids, and glucose. The pymetrozine promoted histological changes are characterized by protrusions and detachments of columnar cells toward the intestinal lumen, presence of vacuolated regenerative cells, and removal of the epithelial lamina in some areas of the muscle layer. The ultrastructure of the midgut in the control group exhibited the basal labyrinth near the mid region of the cell, rough endoplasmic reticulum, Golgi complex, glycogen granules, mitochondria, electron-lucent vesicles, nucleus with well-defined nucleoli, and elongated microvillus. Pymetrozine promoted disarrangement in the basal labyrinth and generated numerous vacuoles and large protrusions between the epithelial lamina and muscular layer. No significant difference was observed in glucose content at 48 h after treatment; however, a significant increase was observed at 144 h after treatment. The glycogen content was reduced in the first 48 h of exposure to pmetrozine and reached the average content of the control insects at 144 h. Significant effects were observed in lipid contents, both in the first 48 h and at 144 h after treatment. Thus, we conclude that pymetrozine compromises the digestive physiology in these insects, affects reproduction, and consequently, it can be a potential alternative to reduce this pest species.
► This study reports structural and biochemical changes of diabetes and exercise. ► Regions of intense cytoplasmic basophilia were observed in control subjects. ► Mitochondria practically filled the ...whole cytosol in diabetic subjects. ► The lower quantity of RER in sedentary diabetics suggests lower protein production. ► It is evident the need for the combined application of a distinct form of treatment.
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 60min 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.
The prion protein (PrP
) has been suggested to operate as a scaffold/receptor protein in neurons, participating in both physiological and pathological associated events. PrP
, laminin, and ...metabotropic glutamate receptor 5 (mGluR5) form a protein complex on the plasma membrane that can trigger signaling pathways involved in neuronal differentiation. PrP
and mGluR5 are co-receptors also for β-amyloid oligomers (AβOs) and have been shown to modulate toxicity and neuronal death in Alzheimer's disease. In the present work, we addressed the potential crosstalk between these two signaling pathways, laminin-PrP
-mGluR5 or AβO-PrP
-mGluR5, as well as their interplay. Herein, we demonstrated that an existing complex containing PrP
-mGluR5 has an important role in AβO binding and activity in neurons. A peptide mimicking the binding site of laminin onto PrP
(Ln-γ1) binds to PrP
and induces intracellular Ca
increase in neurons via the complex PrP
-mGluR5. Ln-γ1 promotes internalization of PrP
and mGluR5 and transiently decreases AβO biding to neurons; however, the peptide does not impact AβO toxicity. Given that mGluR5 is critical for toxic signaling by AβOs and in prion diseases, we tested whether mGlur5 knock-out mice would be susceptible to prion infection. Our results show mild, but significant, effects on disease progression, without affecting survival of mice after infection. These results suggest that PrP
-mGluR5 form a functional response unit by which multiple ligands can trigger signaling. We propose that trafficking of PrP
-mGluR5 may modulate signaling intensity by different PrP
ligands.
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