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Placental malaria, especially when complicated with intervillositis, can cause fetal growth restriction. Transplacental glucose transport by glucose transporter isoform 1 (GLUT-1) on the syncytiotrophoblast microvillous and basal plasma membranes regulates fetal growth. We found that GLUT-1 expression in the microvillous plasma membrane of Plasmodium falciparum-negative placenta biopsy specimens was comparable to that in P. falciparum-positive placenta biopsy specimens with or without intervillositis, whereas GLUT-1 expression in the basal plasma membrane was lowest in P. falciparum-positive placenta biopsy specimens with intervillositis, compared with the other 2 specimen types (P ≤ .0016). GLUT-1 expression in the basal plasma membrane also correlated negatively with monocyte infiltrate density (r = -0.43; P = .003) and positively with birth weight (r = 0.28; P = .06). These findings suggest that intervillositis, more than placental malaria per se, might cause fetal growth restriction, through impaired transplacental glucose transport.

Post-transcriptional regulation of RNA stability and localization underlies a wide array of developmental processes, such as axon guidance and epithelial morphogenesis. In Drosophila, ectopic expression of the classically Golgi peripheral protein dGRASP at the plasma membrane is achieved through its mRNA targeting at key developmental time-points, in a process critical to follicular epithelium integrity. However, the trans-acting factors that tightly regulate the spatio-temporal dynamics of dgrasp are unknown. Using an in silico approach, we identified two putative HOW Response Elements (HRE1 and HRE2) within the dgrasp open reading frame for binding to Held Out Wings (HOW), a member of the Signal Transduction and Activation of RNA family of RNA-binding proteins. Using RNA immunoprecipitations, we confirmed this by showing that the short cytoplasmic isoform of HOW binds directly to dgrasp HRE1. Furthermore, HOW loss of function in vivo leads to a significant decrease in dgrasp mRNA levels. We demonstrate that HRE1 protects dgrasp mRNA from cytoplasmic degradation, but does not mediate its targeting. We propose that this binding event promotes the formation of ribonucleoprotein particles that ensure dgrasp stability during transport to the basal plasma membrane, thus enabling the local translation of dgrasp for its roles at non-Golgi locations.

Cimex hemipterus (Fabricius) is a hematophagous insect that can be an experimental host of Trypanosoma cruzi and may play a role as vector of Chagas' disease. This work analyzed the structure of the salivary glands of C. hemipterus. The secretory portion of main salivary glands has a single oval lobe that is translucent and is formed from a simple columnar epithelium lined by muscle cells. The gland cells are high, with one or two spherical nuclei, nucleolus, and some condensed chromatin. The cell cytoplasm has a well-developed rough endoplasmic reticulum, electron lucent vesicles, lysosomes, and glycogen deposits. The apical plasma membrane has microvilli, zonula adherens, and desmosomes, whereas the basal plasma membrane has some infoldings associated with mitochondria. The duct of the main salivary glands has flattened cells. The secretory portion of the accessory salivary glands is a single vesicular lobe that is translucent and is formed from a single layer of cells that varies from flattened to cubical onto muscle cells. The cytoplasm contains a well-developed smooth endoplasmic reticulum, vacuoles of different sizes containing secretions, electron lucent, and abundant mitochondria. The baso-lateral plasma membrane of adjacent cells shows septate junctions. The duct is formed from a flattened epithelium like the duct of the principal salivary gland. The secretory cells of the main salivary glands are related to protein synthesis and transport of ions. However, the secretory cells of the accessory salivary glands are related mainly to transport of ions and water from the hemolymph to glandular lumen.

The anterior midgut region of stingless bees is anatomically and histologically modified, but its function is uncertain. Here, we describe the ultrastructure of the anterior midgut region of corbiculate bees (Hymenoptera: Apidae) to help understand the structure and function of this section of the digestive tract. The species studied were Apis mellifera L. (Apini), Melipona quadrifasciata anthidioides Leptelier (Meliponini), Bombus morio (Swederus) (Bombini), and Euglossa townsendi Cockrell (Euglossini). The anterior midgut region has a specialized structure only in Meliponini with tall and narrowed cells. However, in M. quadrifasciata anthidioides, as well as in the others species studied, the cells of this midgut region have ultrastrucutural features of digestive cells. The basal plasma membrane infoldings have many openings to the hemocoel, suggesting an absorptive role in this midgut region. The cells of the anterior midgut region of Meliponini, despite having an anatomically and histologically differentiated section, consist of cells with ultrastructural features similar to those of the other corbiculate bees. These cells may play a role in water absorption.

The directional flow of the plant hormone auxin mediates multiple developmental processes, including patterning and tropisms. Apical and basal plasma membrane localization of AUXIN-RESISTANT1 (AUX1) and PIN-FORMED1 (PIN1) auxin transport components underpins the directionality of intercellular auxin flow in Arabidopsis thaliana roots. Here, we examined the mechanism of polar trafficking of AUX1. Real-time live cell analysis along with subcellular markers revealed that AUX1 resides at the apical plasma membrane of protophloem cells and at highly dynamic subpopulations of Golgi apparatus and endosomes in all cell types. Plasma membrane and intracellular pools of AUX1 are interconnected by actin-dependent constitutive trafficking, which is not sensitive to the vesicle trafficking inhibitor brefeldin A. AUX1 subcellular dynamics are not influenced by the auxin influx inhibitor NOA but are blocked by the auxin efflux inhibitors TIBA and PBA. Furthermore, auxin transport inhibitors and interference with the sterol composition of membranes disrupt polar AUX1 distribution at the plasma membrane. Compared with PIN1 trafficking, AUX1 dynamics display different sensitivities to trafficking inhibitors and are independent of the endosomal trafficking regulator ARF GEF GNOM. Hence, AUX1 uses a novel trafficking pathway in plants that is distinct from PIN trafficking, providing an additional mechanism for the fine regulation of auxin transport.

We have investigated re-epithelialization following induction of suction blisters in humans in intact blisters, open wounds, i.e. blister roofs removed immediately after blister induction, and calcipotriol-pretreated open wounds. Intact blisters simulate blister healing in bullous disease, while open wounds simulate re-epithelialization during wound healing. Re-epithelialization was clearly faster in open wounds than in intact blisters, and was not affected by calcipotriol pretreatment. Bullous pemphigoid antigen 2 (BP180), bullous pemphigoid antigen 1 (BP230), plectin/hemidesmosomal 1 protein (HD1), laminin 5, laminin alpha5, laminin beta1, type VII collagen, tenascin-C, beta4, alphavbeta5, alpha5 and alpha9 integrins were studied in intact blisters and open wounds by immunohistochemistry. Hemidesmosomal plaque proteins BP230 and plectin/HD1, which connect the keratin cytoskeleton to the hemidesmosome, appeared earlier at the leading edge in intact blisters than in open wounds. Band-like immunostaining in the basement membrane for laminin 5, alpha5 and beta1 chains was continuous in blister bases, but partially discontinuous in open wound bases. The other antigens studied showed similar expression in intact blisters and open wounds. BP180, BP230, plectin/HD1, beta4 integrin, laminin 5 and tenascin-C expression were further studied in calcipotriol-pretreated open wounds. Calcipotriol did not affect the expression of these antigens. The immunohistochemical results suggest that the keratin cytoskeleton is linked to the basal plasma membrane of migrating basal cells via BP230 and plectin/HD1 earlier in the more slowly re-epithelializing blisters than in open wounds. An intact laminin sheath may inhibit keratinocyte migration in intact blisters.

In the rat hind limb bud aged between prenatal days 14 and 16, immunoreactions of fibronectin in the apical ectodermal ridge were localized on the plasma membranes of epidermal cells and cytoplasmic projections of the underlying mesenchymal cells, which are in contact with the basal lamina. Those of integrin alpha 3 and alpha 5 subunits also appeared on such areas. Definite immunoreactions of fibronectin and both integrin subunits were seen in cell to cell contact areas of mesenchymal cells which are associated with the marginal vein, or with each other forming solid cell cords, and appeared on the basal plasma membrane of endothelial cells of the growing capillaries arising from the marginal vein. These findings suggest that fibronectin may work as a ligand for alpha 3 beta 1 and/or alpha 5 beta 1 integrins expressed by the mesenchymal and vasoformative cells in developing limb bud.

The anterior midgut (crop) cells of Rhodnius prolixus Stl undergo several modifications following a blood meal. The basal plasma membrane is highly folded, and within 2 h of feeding these folds separate so that a large surface area of membrane is exposed for rapid transport of water across the epithelium. On the apical cell surface, extracellular membrane layers are produced, but their extensive proliferation is not seen. In contrast to other midgut regions, no well-defined post-bloodmeal modifications to the lysosomes or rough endoplasmic reticulum are observed. Intracellular spherites are present only in crop cells of Rhodnius and are considered to be reservoirs of inorganic ions retained during diuresis. Large quantities of lipidlike inclusions are also found in the crop cells, many more than in other midgut regions. The crop ultrastructure is related to its functions in rapid diuresis of water from the midgut lumen, in mineral ion regulation, in digestion of some nonprotein components, and as a nutrient storage organ. Differences between the ultrastructure of the anterior and posterior midgut cells are attributed to their different functions during digestion.

SUMMARY.— The fine structure of periderm and germinative cells of the bilaminar epidermis of a 14 mm. human embryo is described. Desmosomes at different stages of differentiation are present at intervals along the apposed plasma membranes of cells of both layers, but hemi-desmosomes have not yet developed along the basal plasma membranes of the germinative cells. Cytoplasmic tono-filaments are not diffusely distributed within the germinative cells, but a continuous band of filamentous material lies just within, and parallel with the basal plasma membrane. Cells occasionally present between periderm and germinative layers exhibit features suggesting they may be immigrant mesenchymal elements.