Maria do Carmo Queiroz Fialho

Ultrastructure and cytochemistry of salivary glands of the predator Podisus nigrispinus (Hemiptera: Pentatomidae.

Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a zoophytophagous insect with a potential for use as a biological control agent in agriculture because nymphs and adults actively prey on various insects by inserting mouthparts and regurgitating the contents of the salivary glands inside the prey, causing rapid paralysis and death. However, the substances found in saliva of P. nigrispinus that causes the death of the prey are unknown. As a first step to identify the component of the saliva of P. nigrispinus, this study evaluated the ultrastructure and cytochemistry of the salivary glands of P. nigrispinus. The salivary system of P. nigrispinus has a pair of principal salivary glands, which are bilobed with a short anterior lobe and a long posterior lobe, and a pair of tubular accessory glands. The principal gland epithelium is composed of a single layer of cells enclosing a large lumen. Epithelial cells of the principal salivary gland vary from cubic to columnar shape, with one or two spherical and well-developed nuclei. Cells of the anterior lobe of the principal salivary gland have an apical surface with narrow, short, and irregular plasma membrane foldings; apical and perinuclear cytoplasm rich in rough endoplasmic reticulum; and mitochondria with tubular cristae. The basal portion of the secretory cells has mitochondria associated with many basal plasma membrane infoldings that are short but form large extracellular canals. Secretory granules with electron-dense core and electron-transparent peripheral are dispersed throughout the cytoplasm. Cells of the posterior lobe of the principal salivary gland are similar to those of the anterior lobe, except for the presence of mitochondria with transverse cristae. The accessory salivary gland cells are columnar with apical microvilli, have well-developed nucleus and cytoplasm rich in rough endoplasmic reticulum, and have secretory granules. Cytochemical tests showed positive reactions for carbohydrate, protein, and acid phosphatase in different regions of the glandular system. The principal salivary glands of P. nigrispinus do not have muscle cells attached to its wall, suggesting that saliva-releasing mechanism may occurs with the participation of some thorax muscles. The cytochemical and ultrastructural features suggest that the principal and accessory salivary glands play a role in protein synthesis of the saliva.

Analysis of the morphology and distribution of argentaffin, argyrophil and insulin-immunoreactive endocrine cells in the small intestine of the adult opossum Didelphis aurita (Wied-Neuwied, 1826)

The aim of this study was to identify and quantify the argyrophil, argentaffin and insulin-immunoreactive cells (IIC) in the small intestine of the opossum Didelphis aurita. Seven adult male specimens of opossums were investigated. The animals were captured, and their blood insulin levels were determined. After euthanasia, fragments of the small intestine were processed for light microscopy and transmission electron microscopy, and submitted to histochemistry and immunohistochemistry for identification of argyrophil and argentaffin endocrine cells, and IIC. Argyrophil and argentaffin cells were identified in the intestinal villi and Liberkühn crypts, whereas IIC were present exclusively in the crypts. Ultrastructure of the IIC revealed cytoplasmic granules of different sizes and electron densities. The numbers of IIC per mm(2) in the duodenum and jejunum were higher than in the ileum (p<0.05). The animals had low levels of blood insulin (2.8 ± 0.78 μIU/ml). There was no correlation between insulin levels and the number of IIC in the small intestine. The IIC presented secretory granules, elongated and variable morphology. It is believed that insulin secretion by the IIC may influence the proliferation of cells in the Liberkühn crypts, and local glucose homeostasis, primarily in animals with low serum insulin levels, such as the opossum.

The expression patterns of aquaporin 9, vacuolar H(+)-ATPase, and cytokeratin 5 in the epididymis of the common vampire bat.

Desmodus rotundus is a vampire bat species that inhabits Latin America. Some basic aspects of this species’ biology are still unknown, as the histophysiological characteristics of the male reproductive tract. Our study has focused on its epididymis, which is an important organ for performing a variety of functions, especially the sperm maturation and storage. The aim of this study was to identify principal, narrow, clear, and basal cells using cell-specific markers such as aquaporin 9 (AQP9), vacuolar H+-ATPase (V-ATPase), and cytokeratin 5 (KRT5). Principal cells were labeled by AQP9 from initial segment to cauda region in their stereocilia. They were shown with a columnar shape, whereas V-ATPase-rich cells were identified with a goblet-shaped body along the entire epididymis, including the initial segment, which were named as clear cells. Pencil-shaped V-ATPase-rich cells (narrow cells) were not detected in the initial segment of the bat epididymis, unlike in the rodent. Basal cells were labeled by KRT5 and were located at the basal portion of the epithelium forming a dense network. However, no basal cells with a luminal-reaching body extension were observed in the bat epididymis. In summary, epithelial cells were identified by their specific markers in the vampire bat epididymis. Principal and basal cells were labeled by AQP9 and KRT5, respectively. Narrow cells were not observed in the vampire bat epididymis, whereas clear cells were identified by V-ATPase labeling along the entire duct in a goblet-shaped body. In addition, no luminal-reaching basal cells were observed in the vampire bat epididymis.

Ultrastructure of the excretory organs of Bombus morio (Hymenoptera: Bombini): bee without rectal pads.

Bumblebees need to keep bodily homeostasis and for that have an efficient system of excretion formed by the Malpighian tubules, ileum, and rectum. We analyzed the excretory organs of Bombus morio, a bee without rectal pads. In addition, we analyzed the rectal epithelium of Melipona quadrifasciata anthidioides which has rectal pads. The Malpighian tubules exhibited two cell types and the ileum four types. However, comparative analysis of the rectum showed that only cells of the anterior region of the rectal epithelium of B. morio are structurally distinct. We suggest that cells of the Malpighian tubules of B. morio have an excretory feature and that cells of ileum have different functions, such as ion absorption and water, organic compound, and protein secretion. In addition, only the anterior region of the rectum of B. morio showed characteristic absorption. We suggest that Malpighian tubules participate in the excretion of solutes and that the ileum and rectal epithelium are responsible for homeostasis of water and solutes, compensating for the absence of rectal papillae. These results contribute to our understanding of the morphophysiology of the excretory organs of bees without rectal pads.

Nonsteroidal anti-inflammatory is more effective than anti-oxidant therapy in counteracting oxidative/nitrosative stress and heart disease in T. cruzi-infected mice

We compared the relevance of ibuprofen, vitamins C and E to control oxidative/nitrosative stress and heart disease in mice infected by Trypanosoma cruzi. Swiss mice were randomized into five groups: control, uninfected; infected without treatment; and infected treated with vitamins C, E or ibuprofen. Animals were inoculated with 2000 trypomastigote forms of T. cruzi. After 20 days, infected mice presented reduced vitamin C and E tissue levels, high cytokines (interferon gamma, tumour necrosis factor-α, interleukin 10 and chemokine ligand 2), prostaglandin F2α (PGF2α ) and nitric oxide (NO) cardiac production, intense myocarditis and reactive tissue damage, which was directly correlated with the intensity of the inflammatory infiltrate and the degree of pathological cardiac remodelling. Vitamins C and E supplementation were irrelevant to counteract reactive tissue damage and myocarditis in infected animals. Conversely, ibuprofen reduced tissue levels of cytokines, PGF2α and NO, as well as lipid and protein oxidation, antioxidant enzyme activity and the cardiac damage, without interfering with heart parasitism. Our results do not support the applicability of vitamin C and E supplementation in the management of acute Chagas cardiomyopathy. By controlling the inflammatory infiltrate, anti-inflammatory-based therapy proved to be a more rational strategy than a direct antioxidant therapy in attenuating oxidative/nitrosative stress and cardiac damage.

Stink bug predator kills prey with salivary non-proteinaceous compounds.

Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a predator insect with potential applications in biological control because both nymphs and adults have been shown to prey on other insect pests by injection of toxic salivary gland contents. This study identified non-proteinaceous compounds with insecticidal activity from the saliva of P.xa0nigrispinus in Anticarsia gemmatalis. In particular, the ether extract from P.xa0nigrispinus saliva led to mortality in A.xa0gemmatalis larvae, with a LC50xa0=xa02.04xa0μL and LC90xa0=xa03.27xa0μL. N,N-dimethylaniline and 1,2,5-trithiepane fractions were identified as non-proteinaceous extract components. N,N-dimethylaniline had a LC50xa0=xa0136.1xa0nL and LC90xa0=xa0413.8xa0nL, suggesting that it could be responsible for toxicity in P.xa0nigrispinus saliva.

A comparative study of the antennal sensilla in corbiculate bees

Summary Sensilla are the basic structures that allow the perception of environmental cues that play a role as mechanoreceptors, chemoreceptors, thermoreceptors and hygroreceptors associated with their morphology. Because bees have different degrees of sociability, they are a good model for the study of sensilla types and distribution linked with behaviour. This work identifies the types of sensilla in the antennae of bees with different degrees of sociability. The antennae of 18 species of bee were analysed with a scanning electron microscope. Trichoid and placoid sensilla are present in all antennomers of the species studied. The honey bee Apis mellifera and bumble bee Bombus pauloensis workers have higher diversity and sensillum distribution in comparison with males. In stingless bees, species of Meliponaare representative of a homogeneous group for sensilla types and distribution. The types and distribution of sensilla in the antennae of bees seems to be associated with the degree of sociability.

Cadmium-induced testicular damage is associated with mineral imbalance, increased antioxidant enzymes activity and protein oxidation in rats

Aims: Currently, the spectrum of pathological manifestations associated with cadmium‐induced testicular toxicity is poorly understood. Thus, we investigated the impact of cadmium (Cd) exposure on testicular mineral bioavailability, activity of antioxidant enzymes, testicular structure and germ cells ultrastructure Main methods: Cadmium chloride was administered in a single dose to thirty rats equally randomized into five groups: Saline, 0.9% NaCl; Cd1 – Cd4, 0.67, 0.74, 0.86 and 1.1 mg Cd/kg. Seven days after Cd exposure, animals were euthanized and testes were collected for biochemical analysis, as well as light, scanning and transmission electron microscopy. Key findings: Cadmium exposure induced dose‐dependent testicular toxicity. Tubular and intertubular compartments were targets of Cd and calcium (Ca) deposits, marked structural and ultrastructural pathologic remodeling, and a reduced distribution of iron, selenium, magnesium, copper, zinc and total protein. Despite upregulation in antioxidant enzyme activities (i.e. catalase [CAT] and superoxide dismutase [SOD]), morphologic and molecular testis damage such as protein oxidation was not prevented, especially with higher doses of Cd. As non‐degenerated tissue areas also presented Ca deposits, Ca imbalance was not only a consequence but also a cause of Cd‐induced testis toxicity and germ cell death Significance: Taken together, our findings indicated that Cd exposition induced dose‐dependent testicular dystrophic calcification, which was associated with increased antioxidant enzymes activity and protein oxidation, mineral imbalance, germ cell calcification and death in rats. Although increased CAT and SOD activity represents a counter‐regulatory reaction to cadmium‐induced toxicity, this reaction is insufficient to prevent testicular pathological remodeling.

Changes in follicular cells architecture during vitellogenin transport in the ovary of social Hymenoptera

Vitellogenins are the major yolk proteins, synthesized in the fat body, released into the hemolymph and captured by the developing oocytes, but the mechanisms by which these proteins cross the follicular cell layer are still poorly understood. This study describes the actin distribution in follicular cells during vitellogenin transport to the oocyte in social Hymenoptera represented by bees Apis mellifera and Melipona quadrifasciata, the wasp Mischocyttarus cassununga and the ant Pachycondyla curvinodis. In oocytic chambers of vitellogenic follicles, vitellogenin was found within the follicular cells, perivitelline space and oocyte, indicating a transcellular route from the hemolymph to the perivitelline space. The cortical actin cytoskeleton in follicular cells underwent reorganization during transport of vitellogenin across this epithelium suggesting that in the ovary of social hymenopterans, vitellogenin delivery to oocytes requires a dynamic cytoskeletal rearrangement of actin filaments in the follicular cells.

Aquaporins in the honeybee crop—a new function for an old organ

Nectar used by bees as a food source is collected and stored in the crop, where it is transported and converted into honey. The production of honey involves water uptake from nectar. However, the crop is a portion of the insect foregut that has been characterized solely as a food storage organ. Aquaporins are integral membrane proteins that function as specific canal for water transport and are abundant in tissues with high water permeability. In this study, we detected five predicted genes for aquaporins in the gut of the honeybee Apis mellifera. We evaluated the aquaporins’ localization in the crop by using an anti-aquaporin antibody produced against the peptide sequence from one of the expressed genes, which was detected in the crop epithelium, particularly in the apical portions of the cells. Furthermore, we also showed an increase in sugar concentration in a sucrose solution collected from the crop lumen a few minutes after feeding, indicating that water uptake occurs during storage of nectar in the crop, suggesting a previously unidentified function for the honeybee crop.