Showing papers on "Apical cytoplasm published in 2018"

Sublethal dose of deltamethrin damage the midgut cells of the mayfly Callibaetis radiatus (Ephemeroptera: Baetidae)

Abstract: In insects, the midgut performs multiple physiologic functions (e.g., digestion and nutrients absorption) and serves as a physical/chemical barrier against pathogens and chemical stressors such as deltamethrin, a pyrethroid insecticide, commonly used in insect control that are agricultural pests and human disease vectors. Here, we described the midgut cell ultrastructure of Callibaetis radiatus nymphs, which are bioindicators of water quality and the ultrastructural alterations in midgut under sublethal exposure to deltamethrin at three different periods (1, 12, 24 h). The digestive cells of deltamethrin-unexposed nymphs had long microvilli, many mitochondria in the apical cytoplasm, a rough endoplasmic reticulum, a basal labyrinth with openings for hemocele, and the midgut peritrophic matrix which is classified as type I. Nymphs exposed to deltamethrin exhibited digestive cells rich in autophagic vacuoles, basal labyrinth loss, and microvilli disorganization since the first hour of contact with deltamethrin. However, these midgut tissues underwent to autophagic cellular recovery along the 24 h of exposure to deltamethrin. Thus, the sublethal exposure to deltamethrin is sufficient to disturb the ultrastructure of C. radiatus midgut, which might reduce the abilities of these insects to survive in aquatic environments contaminated by pyrethroids.

Electromechanics of polarized cell growth

Abstract: One of the most challenging questions in cell and developmental biology is how molecular signals are translated into mechanical forces that ultimately drive cell growth and motility. Despite an impressive body of literature demonstrating the importance of cytoskeletal and motor proteins as well as osmotic stresses for cell developmental mechanics, a host of dissenting evidence strongly suggests that these factors per se cannot explain growth mechanics even at the level of a single tip-growing cell. The present study addresses this issue by exploring fundamental interrelations between electrical and mechanical fields operating in cells. In the first instance, we employ a simplified but instructive model of a quiescent cell to demonstrate that even in a quasi-equilibrium state, ion transport processes are conditioned principally by mechanical tenets. Then we inquire into the electromechanical conjugacy in growing pollen tubes as biologically relevant and physically tractable developmental systems owing to their extensively characterized growth-associated ionic fluxes and strikingly polarized growth and morphology. A comprehensive analysis of the multifold stress pattern in the growing apices of pollen tubes suggests that tip-focused ionic fluxes passing through the polyelectrolyte-rich apical cytoplasm give rise to electrokinetic flows that actualize otherwise isotropic intracellular turgor into anisotropic stress field. The stress anisotropy can be then imparted from the apical cytoplasm to the abutting frontal cell wall to induce its local extension and directional cell growth. Converging lines of evidence explored in the concluding sections attest that tip-focused ionic fluxes and associated interfacial transport phenomena are not specific for pollen tubes but are also employed by a vast variety of algal, plant, fungal and animal cells, rendering their cytoplasmic stress fields essentially anisotropic and ultimately instrumental in cell shaping, growth and motility.

Morphofunctional analysis of antigen uptake mechanisms following sublingual immunotherapy with beads in mice.

Abstract: Background Recently, sublingual immunotherapy (SLIT) has been used as a safe and efficient method for the treatment of and immunization against asthma and various allergies. However, the routes of antigen/allergen (particulate antigen) uptake through the mucosa of the oral cavity remain incompletely understood, as do the roles of sex and age in the process. For this purpose, to elucidate the mechanism and efficacy of SLIT among different sexes and ages, microbeads were dripped into the sublingual region to mimic particulate antigen uptake by the sublingual mucosa. Methods Twenty microliters of either phosphate buffered saline (PBS) or fluorescently labelled microbeads (latex and silica beads) were placed under the tongue of both male and female C57BL/6 mice at young (3 months) and old (6 months) ages. The lower jaw was examined 30 min after administration, and beads were detected with a fluorescence stereomicroscope. Morphological observations of the mucosa of the fluorescent areas were made with a scanning electron microscope (SEM) and an all-in-one light fluorescence microscope (LM). Fluorescence intensity was compared between both sexes and ages. Results Stereomicroscopic observation revealed fluorescent illuminations in three compartments of the sublingual mucosa: the sublingual caruncles (SC), the oral rostral mucosa (OR) and the buccal mucosa (BM). Interestingly, the fluorescence intensity tended to be higher among females than among males in the SC region in particular. However, there were no significant age-related differences. SEM and LM revealed beads in the lumina of both mandibular ducts and sublingual ducts (Sd). Additionally, the apical cytoplasm of some Sd cells contained silica beads. However, there was no specification in the OR mucosa or BM. Conclusions This study reveals the major role Sd plays in local immunity via the antigen uptake mechanisms. Furthermore, our data suggest that the efficacy of SLIT in humans could be affected by sex.

Differential effects of depot formulations of GnRH agonist leuprorelin and antagonist degarelix on the seminiferous epithelium of the rat testis.

Abstract: Despite their pharmacologically opposite actions, long-acting depot formulations of both GnRH agonists and antagonists have been clinically applied for treatment of androgen-sensitive prostate cancer. Sustained treatment with GnRH analogues commonly suppresses both the synthesis and release of gonadotropins, leading to depletion of testicular testosterone. To clarify the underlying differences in the effects of GnRH agonists and antagonists on spermatogenesis, we compared histological changes in the seminiferous epithelium after administration of depot formulations of GnRH agonist leuprorelin and antagonist degarelix to male rats. Testicular weight had markedly declined by 28 days after administration of both GnRH analogues, although the testicular weight was decreased more promptly by leuprorelin compared with degarelix. Shortly after administration, massive exfoliation of premature spermatids and anomalous multinucleated giant cells was observed in seminiferous tubules of leuprorelin-treated rats, probably via the initial hyperstimulatory effects on the hypothalamic-pituitary-testicular axis, whereas no discernible changes were found in those of degarelix-treated rats. Long term treatment with both types of GnRH analogues similarly induced a marked reduction in the height of the epithelium and deformation of apical cytoplasm in Sertoli cells, resulting in premature detachment of spermatids from the epithelium. Lipid droplets had accumulated progressively in Sertoli cells, especially in those of degarelix-treated rats. These findings clearly demonstrate the differences in the effects of GnRH agonists and antagonists on the spermatogenic process. This study suggests that an appropriate choice of GnRH analogues is necessary to minimize their adverse effects on spermatogenesis when reproductive functions should be preserved in patients.

Morphofunctional analysis of antigen uptake mechanisms following sublingual immunotherapy with beads in mice

Abstract: Background Recently, sublingual immunotherapy (SLIT) has been used as a safe and efficient method for the treatment of and immunization against asthma and various allergies. However, the routes of antigen uptake through the mucosa of the oral cavity remain incompletely understood, as do the roles of sex and age in the process. For this purpose, to elucidate the mechanism and efficacy of SLIT among different sexes and ages microbeads were dripped into the sublingual region to mimic antigen uptake by the sublingual mucosa. Methods Twenty microliters of either phosphate buffered saline (PBS) or fluorescently labelled microbeads (latex and silica beads) were placed under the tongue of both male and female C57BL/6 mice at young (3 months) and old (6 months) ages. The lower jaw was examined 30 min after administration, and beads were detected with a fluorescence stereomicroscope. Morphological observations of the mucosa of the fluorescent areas were made with scanning electron microscopy (SEM) and an all-in-one light fluorescence microscope (LM). Fluorescence intensity was compared between both sexes and ages. Results Stereomicroscopic observation revealed fluorescent illuminations in three compartments of the sublingual mucosa: the sublingual caruncles (SC), the oral rostral mucosa (OR) and the buccal mucosa (BM). Interestingly, the fluorescence intensity tended to be higher among females than among males in the SC region in particular. However, there were no significant age-related differences. SEM and LM revealed beads in the lumina of both mandibular ducts and sublingual ducts (Sd). Additionally, the apical cytoplasm of some Sd cells contained silica beads. However, there were no specification in the OR mucosa or BM. Conclusions This study reveals the major role Sd play in local immunity via the antigen uptake mechanisms. Furthermore, our data suggest that the efficacy of SLIT in humans could be affected by sex.

Prostate-specific membrane antigen and renal cell carcinoma: a new diagnostic and therapeutic target?

Abstract: The prostate-specific membrane antigen (PSMA) is a membrane glycoprotein (type II-carboxypeptidase) encoded by the FOLH1 gene, which is hyper-expressed in prostate cancer (PCa). 68Ga-PSMA PET/CT is a new diagnostic tool for the localization of PCa foci in patients with biochemical recurrence. Its use in pre-surgical staging as well as in early treatment evaluation is also under investigation (1). Moreover, the possibility of labeling PSMA antagonists with radionuclides emitting α and/or β-particles is becoming an interesting therapeutic application for the same molecule (2). However, PSMA, despite its name, is not really specific for PCa as it is also expressed by endothelial cells in the neovascular tissue of many solid tumors including kidney cancer. It has also been reported that the expression of PSMA in normal renal parenchyma can be detected within the brush borders and apical cytoplasm in a subset of proximal tubules (3,4).