Cytotoxic effects on the midgut, hypopharyngeal, glands and brain of Apis mellifera honey bee workers exposed to chronic concentrations of lambda-cyhalothrin.

The honeybee, Apis mellifera is economically important for its products (honey, wax, and propolis) and for its role in pollination. This insect is threated due to high population losses in both agriculture and beekeeping. Within causes involved in the loss of honeybees is the increased pesticide use on agriculture. Although current testing for the regularization of insecticide use considers its acute toxic effects on pollinators, little is known about the effects of chronic exposure to sublethal concentrations that may persist in the environment. This study investigated the effect of chronic exposure to sublethal concentrations of lambda-cyhalothrin on the midgut, hypopharyngeal glands, and brain of A. mellifera. Honey bees were fed for eight days with LC50/100 insecticide. Subsequently, the midgut, hypopharyngeal glands, and brain were analyzed in light and transmission electron microscopies. The midgut was not affected after exposure, except in the posterior region with cell fragments in the lumen and changes in the mitochondria. The hypopharyngeal glands were severely affected by the insecticide with changes in the rough endoplasmic reticulum and cell death. The brain has extensive gaps in the neuropil as well as in the cellular bodies, especially in the corpora pedunculata. These resembled cellular alterations similar to those seen in death processes. The results of this study indicate that lambda-cyhalothrin is toxic to bees at sublethal concentrations and ingested chronically, causing damage to the midgut, hypopharyngeal glands, and brain, and may affect physiological and behavioral aspects of these insects.

Microarchitecture of the tsetse fly proboscis.

BACKGROUND: Tsetse flies (genus Glossina) are large blood-sucking dipteran flies that are important as vectors of human and animal trypanosomiasis in sub-Saharan Africa. Tsetse anatomy has been well described, including detailed accounts of the functional anatomy of the proboscis for piercing host skin and sucking up blood. The proboscis also serves as the developmental site for the infective metacyclic stages of several species of pathogenic livestock trypanosomes that are inoculated into the host with fly saliva. To understand the physical environment in which these trypanosomes develop, we have re-examined the microarchitecture of the tsetse proboscis. RESULTS: We examined proboscises from male and female flies of Glossina pallidipes using light microscopy and scanning electron microscopy (SEM). Each proboscis was removed from the fly head and either examined intact or dissected into the three constituent components: Labrum, labium and hypopharynx. Our light and SEM images reaffirm earlier observations that the tsetse proboscis is a formidably armed weapon, well-adapted for piercing skin, and provide comparative data for G. pallidipes. In addition, the images reveal that the hypopharynx, the narrow tube that delivers saliva to the wound site, ends in a remarkably ornate and complex structure with around ten finger-like projections, each adorned with sucker-like protrusions, contradicting previous descriptions that show a simple, bevelled end like a hypodermic needle. The function of the finger-like projections is speculative; they appear to be flexible and may serve to protect the hypopharynx from influx of blood or microorganisms, or control the flow of saliva. Proboscises were examined after colonisation by Trypanosoma congolense savannah. Consistent with the idea that colonisation commences in the region nearest the foregut, the highest densities of trypanosomes were found in the region of the labrum proximal to the bulb, although high densities were also found in other regions of the labrum. Trypanosomes were visible through the thin wall of the hypopharynx by both light microscopy and SEM. CONCLUSIONS: We highlight the remarkable architecture of the tsetse proboscis, in particular the intricate structure of the distal end of the hypopharynx. Further work is needed to elucidate the function of this intriguing structure.

Comparing the secretory pathway in honeybee venom and hypopharyngeal glands.

We provide insights into the secretory pathway of arthropod gland systems by comparing the royal jelly-producing hypopharyngeal glands and the venom-producing glands of the honeybee, Apis mellifera. These glands have different functions and different product release characteristics, but both belong to the class 3 types of insect glands, each being composed of two cells, a secretory cell and a microduct-forming cell. The hypopharyngeal secretory cells possess an extremely elongate tubular invagination that is filled with a cuticular structure, the end-apparatus, anchored against the cell membrane by a conspicuous series of actin rings. In contrast, venom glands have no actin rings, but instead have an actin-rich brush border surrounding the comparatively short and narrow end-apparatus. We relate these cytoskeletal differences to the production system and utilisation of secretions; venom is stored in a reservoir whereas royal jelly and enzymes are produced on demand. Fluorescence-based characterisation of the actin cytoskeleton combined with scanning electron microscopy of the end-apparatus allows for detailed characterisation of the point of secretion release in insect class 3 glands.

Proteome comparison of hypopharyngeal gland development between Italian and royal jelly producing worker honeybees (Apis mellifera L.).

The hypopharyngeal gland (HG) of the honeybee (Apis mellifera L.) produces royal jelly (RJ) that is essential to feed and raise broods and queens. A strain of bees (high royal jelly producing bee, RJb) has been selected for its high RJ production, but the mechanisms of its higher yield are not understood. In this study, we compared HG acini size, RJ production, and protein differential expressions between the RJb and nonselected honeybee (Italian bee, ITb) using proteomics in combination with an electron microscopy, Western blot, and quantitative real-time PCR (qRT-PCR). Generally, the HG of both bees showed age-dependent changes in acini sizes and protein expression as worker behaviors changed from brood nursing to nectar ripening, foraging, and storage activities. The electron microscopic analysis revealed that the HG acini diameter of the RJb strain was large and produced 5 times more RJ than the ITb, demonstrating a positive correlation between the yield and HG acini size. In addition, the proteomic analysis showed that RJb significantly upregulated a large group of proteins involved in carbohydrate metabolism and energy production, those involved in protein biosynthesis, development, amino acid metabolism, nucleotide and fatty acid, transporter, protein folding, cytoskeleton, and antioxidation, which coincides with the fact that the HGs of the RJb strain produce more RJ than the ITb strain that is owing to selection pressure. We also observed age-dependent major royal jelly proteins (MRJPs) changing both in form and expressional intensity concurrent with task-switching. In addition to MRJPs, the RJb overexpressed proteins such as enolase and transitional endoplasmic reticulum ATPase, protein biosynthesis, and development proteins compared to the ITb strain to support its large HG growth and RJ secretion. Because of selection pressure, RJb pursued a different strategy of increased RJ production by involving additional proteins compared to its original counterpart ITb. To our knowledge, this morphological and proteomic comparison study on the HG of the two strains of worker honeybees associated with their age-dependent division of labor is the first of its kind. The study provided not only the quantity and quality differences in the HG from the RJb and the ITb, but also addressed the cellular and behavioral biology development question of how the RJb strain can produce RJ more efficiently than its wild type strain (ITb).

Distribution of acid phosphatases in the hypopharyngeal glands from workers, queens and males of a Brazilian stingless bee Scaptotrigona postica Latreille: an ultrastructural cytochemical study.

The present study reports the localization of acid phosphatase in the hypopharyngeal gland cells from workers (newly-emerged, nurse and forager), queens (newly-emerged and laying) and males (newly-emerged and mature for mating) of the Brazilian stingless bee, Scaptotrigona postica. The phosphatase activity varied in intensity and localization depending on the individual class, physiological age and the substrate used. In newly-emerged workers, the phosphatase-positive sites suggest the involvement of the enzyme with cellular differentiation that occurs in the presecretory phase, in nurse workers with protein synthesis and in forager workers with changes in cellular activity or glandular regression. In males mature for mating and laying queens, the positive sites are related to secretory activity, showing that the gland maintains some activity in spite of the regressive aspect. Of the substrates used, beta-glycerophosphate gave the least specific localization.

Comparative study of the ultrastructure and secretory dynamic of hypopharyngeal glands in queens, workers and males of Scaptotrigona postica Latreille (Hymenoptera, Apinae, Meliponini).

The secretory cycle of hypopharyngeal glands (HPGs) in Scaptotrigona postica resembles that of Apis mellifera: in newly emerged workers the HPGs are in prefunctional state, their maximum development happens in the nurse workers and in forager workers they show signs of reabsorption. In S. postica these glands are also present in queens and males where they are more developed in newly emerged individuals. The ultrastructural features of the HPG secretory cycle in workers of S. postica and A. mellifera are alike: granular endoplasmic reticulum well developed, large secretion masses around the intracellular canaliculus in nurse workers and extensive degenerative structures in forager workers. Then it is suggested that the HPG secrete similar substances in both species. A second secretory cycle seems to occur in early foragers, may be with production of enzymes. The role of the HPGs in queens and males remains unknown but one possibility is enzyme production.

Comparative study of the ultrastructure and secretory dynamic of hypopharyngeal glands in queens, workers and males of Scaptotrigona postica Latreille (Hymenoptera, Apinae, Meliponini)

The secretory cycle of hypopharyngeal glands (HPGs) in Scaptotrigona postica resembles that of Apis mellifera: in newly emerged workers the HPGs are in prefunctional state, their maximum development happens in the nurse workers and in forager workers they show signs of reabsorption. In S. postica these glands are also present in queens and males where they are more developed in newly emerged individuals. The ultrastructural features of the HPG secretory cycle in workers of S. postica and A. mellifera are alike: granular endoplasmic reticulum well developed, large secretion masses around the intracellular canaliculus in nurse workers and extensive degenerative structures in forager workers. Then it is suggested that the HPG secrete similar substances in both species. A second secretory cycle seems to occur in early foragers, may be with production of enzymes. The role of the HPGs in queens and males remains unknown but one possibility is enzyme production.(AU)

Surgical treatment for hypopharyngeal cysts with a side-opened direct laryngoscope.

Two cases of hypopharyngeal cyst are reported. Both cysts occurred in the piriform sinus of the hypopharynx. Histopathological examination indicated that both were retention cysts. These cysts were removed by laryngomicrosurgical technique using a side-opened direct laryngoscope. In the cyst with a distinct base, a laryngomicrosurgical snare was used for removal. In the wide-based cyst, the mucous membrane around the cyst was incised with an electrosurgical instrument and then detached to facilitate removal. In this paper, we describe our surgical procedure for removing hypopharyngeal cysts and discuss the causes of such cysts.

Stereo architecture of the lamina propria in the mouse laryngopharynx in scanning electron microscopy.

In the ventral wall of the mouse laryngopharynx, a fairly large number of the epithelial papillae containing taste bud (provisionally denominated the pharyngeal papillae) were observed. The NaOH cellmaceration method was applied in order to demonstrate the stereo architecture of the connective tissue papillae (CTP) of the pharyngeal papillae. The CTP appeared as a cylindrical wall surrounding a round depression, and consisted of a delicate meshwork of collagen fibrils. It is suggested that the CTP constitute the skeletal framework of the pharyngeal papillae and that the round depression corresponds to the site of taste bud. Furthermore, the collagen fibrillar architecture in the extrapapillary region appeared to be arranged to meet specific functional needs. That is, in the rostral end of the laryngopharynx, the collagen fibrils ran solitarily to form a coarse meshwork and seemed to allow the epithelium a certain degree of freedom of motion in swallowing. On the other hand, in the caudal part the fibrils concentrated into the thick bundles of the fibers running side by side along the long axis of the laryngopharynx and, therefore, appeared to play an important role in resisting the excessive stretching force.