Glial fibrillary acidic protein and desmin in salivary neoplasms. Expression of four different types of intermediate filament proteins within the same cell type

The presence of intermediate filament proteins (IFP) in normal salivary gland tissue and investigated by immunohistochemical techniques on frozen sections. Cytokeratins (CKs) were seen in almost all normal epithelial cells. In the parotid gland and in palatal gland tissue, a co-expression of cytokeratin and glial fibrillary acidic protein (GFAP) was seen in some myoepithelial cells, but this was not apparent in the submandibular gland. In some pleomorphic adenomas, carcinomas in pleomorphic adenomas, one mucoepidermoid carcinoma, one mucus-producing adenopapillary carcinoma and one adenoid cystic carcinoma, cells expressing three different IFP classes were found (CKs, vimentin, GFAP). These cells were most often situated peripherally in the tumour cords or ducts. The cytokeratin pattern in these cells, as revealed by mAbs PKK1-3, was similar to that in normal myoepithelial cells. Furthermore, reactivity for a fourth class of IFP, desmin, could be seen in this cell type in two carcinomas in pleomorphic adenomas, and also in a few cells in a pleomorphic adenoma and an adenoid cystic carcinoma. Thus the pattern of IFP expression in salivary gland neoplasms, is very complex, and cannot always be related to the normal tissue.     

Effect of dimethylglycine and trimethylglycine (Betaine) on the response of Atlantic salmon (Salmo salar L.) smolts to experimental Vibrio anguillarum infection

Atlantic salmon (Salmo salar L.) were fed on a control diet or experimental diets containing betaine (15 mg g^-1) or dimethylglycine (DMG, I mg g^-1 or 5 mg g^-1). After 10 weeks of feeding, resistance to infection was assessed following inoculation with Vibrio anguillarum. Total blood and differential leucocyte counts were made, and plasma lysozyme and ceruloplasmin were assayed as non-specific humoral factors. The mortality during the bacterial exposure was of the same magnitude in all feeding groups. Betaine or DMG had no effect on the 'basal' levels of plasma total protein, lysozyme or ceruloplasmin, but 3 days postinjection the lysozyme and ceruloplasmin levels were higher in the control group compared with the experimental groups. In both DMG groups, the lymphocyte response took place 1-2 weeks earlier than in the control or betaine supplemented group indicating that DMG has an immunomodulating effect on salmon.     

Intracellular localization of factor VIII-related antigen and fibronectin in cultured human endothelial cells: evidence for divergent routes of intracellular translocation

Cultured human endothelial cells synthesize and secrete both fibronectin and factor VIII-related antigen (VIIIR:Ag). In immunofluorescence microscopy, intracellular fibronectin was seen diffusely perinuclearly whereas VIIIR:Ag was located both diffusely in the perinuclear cytoplasm and in distinct rod-shaped granules. These granules could, moreover, be visualized with fluorochrome-coupled Ricinus communis agglutinin I (RCA), which also stained the Golgi apparatus as a reticular juxtanuclear structure, and they were identified as Weibel-Palade bodies by immunoelectron microscopy. Puromycin treatment depleted intracellular fibronectin but did not affect the granular localization of VIIIR:Ag. A short exposure of the cells to monensin caused a juxtanuclear accumulation of fibronectin at the Golgi region whereas VIIIR:Ag only was seen in rounded cytoplasmic granules. A prolonged monensin treatment brought about a cytoplasmic accumulation of fibronectin-containing vesicles whereas VIIIR:Ag showed no accumulation and there was no codistribution between granules containing fibronectin or VIIIR:Ag. Type IV procollagen, on the other hand, was distinctly co-localized with fibronectin. In monensin-treated cells RCA mainly stained the VIIIR:Ag-containing vesicles whereas Concanavalin A (Con A) appeared to label the fibronectin-containing vesicles. Immunoelectron microscopy of these cells revealed VIIIR:Ag in some vacuolar structures and typical Weibel-Palade bodies could not be identified. Exposure of the cells to tunicamycin, on the other hand, caused a prominent cytoplasmic accumulation of VIIIR:Ag and, within 96 h, led to the disappearance of most of the VIIIR:Ag-positive granules but did not affect the intracellular distribution of fibronectin. These results, which show that metabolical inhibitors affect differently the intracellular compartmentalization of fibronectin and VIIIR:Ag, indicate, that the two glycoproteins have divergent intracellular pathways in cultured human endothelial cells.     

Inhibition of Klenow DNA polymerase and poly(A)-specific ribonuclease by aminoglycosides

Aminoglycosides are known to bind and perturb the function of catalytic RNA. Here we show that they also are potent inhibitors of protein-based catalysis using Escherichia coli Klenow polymerase (pol) and mammalian poly(A)-specific ribonuclease (PARN) as model enzymes. The inhibition was pH dependent and released in a competitive manner by Mg2+. Kinetic analysis showed that neomycin B behaved as a mixed noncompetitive inhibitor. Iron-mediated hydroxyl radical cleavage was used to show that neomycin B interfered with metal-ion binding in the active sites of both enzymes. Our analysis suggests a mechanism of inhibition where the aminoglycoside binds in the active site of the enzyme and thereby displaces catalytically important divalent metal ions. The potential causes of aminoglycoside toxicity and the usage of aminoglycosides to probe, characterize, and perturb metalloenzymes are discussed.     

Immunolocalization of tenascin and cellular fibronectins in diverse glomerulopathies

Frozen samples of minimal change glomerulopathy (MCG), and of membranous, segmental and diffuse lupus glomerulonephritis (MGN, SGN, DLGN) were studied to assess the distribution of tenascin (Ten), and the extradomains A and B (EDA-and EDB-) and oncofetal (Onc-) isoforms of cellular fibronectin (cFn). Cryosections were immunostained by the ABC method with specific monoclonal antibodies. In MCG, mesangial Ten and EDA-cFn reactions were increased. In MGN, mesangial Ten and EDA-cFn staining was enhanced except in segmental scars; convincing reactions were seen in cases with membranous transformation; spikes stained strongly. In SGN, variably intense staining for Ten and all cFn isoforms was seen in glomerular necrosis, proliferation and crescents; parietal epithelium EDA-cFn staining was noted. In DLGN, strong and extensive mesangial Ten and EDA-cFn staining was seen as were focal EDB-and Onc-cFn reactions. Parietal cells with and without crescents stained variably with all Mabs. Obsolete glomeruli were unreactive save for rare periglomerular Ten rims. Interstitial inflammation and fibrosis in MGN, SGN and DLGN had moderate to strong Ten and EDA-cFn staining with rare traces of EDB-and Onc-cFn. We conclude that enhanced Ten and EDA-cFn is a potentially reversible response to glomerular injury whereas the expression of EDB-and Onc-cFn apparently result from necrosis and/or cellular proliferation which lead to scarring. And, while mesangial cells are the major source of these molecules, epithelial cells might also partake in their synthesis.     

Performance of moth larvae on birch in relation to altitude, climate, host quality and parasitoids

We studied topographical and year-to-year variation in the performance (pupal weights, survival) and larval parasitism of Epirrita autumnata larvae feeding on mountain birch in northernmost Finland in 1993–1996. We found differences in both food plant quality and parasitism between sites ranging from 80 m to 320 m above sea level. Variation in food plant quality had particularly marked effects on larval survival. The advanced phenology of the birches in relation to the start of the larval period reduced pupal weights. Parasitism rates were different between years and between sites. The clearest site differences were in the proportions of different parasitoid species: Eulophus larvarum was most abundant at the lowest-altitude sites, and Cotesia jucunda at the highest. Differences in the performance of E. autumnata were related to temperature conditions: at higher temperatures, survival and the egg production index were lower, and larval parasitism was higher than at lower temperatures. The higher parasitism at higher temperatures was probably due to greater parasitoid activity during warmer days. In the comparison of different sources of spatial and annual variation in the performance of E. autumnata, the most important factor appeared to be egg mortality related to minimum winter temperature, followed by parasitism and, finally, the variation in food plant quality. If, as predicted, the climate gradually warms up, the effects of warmer summers on the outbreaks of E. autumnata suggest a decrease in outbreak intensity. Received: 4 January 1999 / Accepted: 22 March 1999     

Seasonal Phenology and Species Composition of the Aphid Fauna in a Northern Crop Production Area

Background

The species diversity of aphids and seasonal timing of their flight activity can have significant impacts on crop production, as aphid species differ in their ability to transmit plant viruses and flight timing affects virus epidemiology. The aim of the study was to characterise the species composition and phenology of aphid fauna in Finland in one of the northernmost intensive crop production areas of the world (latitude 64°).

Methodology/Principal Findings

Flight activity was monitored in four growing seasons (2007–010) using yellow pan traps (YPTs) placed in 4–8 seed potato fields and a Rothamsted suction trap. A total of 58,528 winged aphids were obtained, identified to 83 taxa based on morphology, and 34 species were additionally characterised by DNA barcoding. Seasonal flight activity patterns analysed based on YPT catch fell into three main phenology clusters. Monoecious taxa showed early or middle-season flight activity and belonged to species living on shrubs/trees or herbaceous plants, respectively. Heteroecious taxa occurred over the entire potato growing season (ca. 90 days). Abundance of aphids followed a clear 3-year cycle based on suction trap data covering a decade. Rhopalosiphum padi occurring at the end of the potato growing season was the most abundant species. The flight activity of Aphis fabae, the main vector of Potato virus Y in the region, and Aphis gossypii peaked in the beginning of potato growing season.

Conclusions/Significance

Detailed information was obtained on phenology of a large number aphid species, of which many are agriculturally important pests acting as vectors of plant viruses. Aphis gossypii is known as a pest in greenhouses, but our study shows that it occurs also in the field, even far in the north. The novel information on aphid phenology and ecology has wide implications for prospective pest management, particularly in light of climate change.     

The murine IgM secretory poly(A) site contains dual upstream and downstream elements which affect polyadenylation.

Regulation of polyadenylation efficiency at the secretory poly(A) site plays an essential role in gene expression at the immunoglobulin (IgM) locus. At this poly(A) site the consensus AAUAAA hexanucleotide sequence is embedded in an extended AU-rich region and there are two downstream GU-rich regions which are suboptimally placed. As these sequences are involved in formation of the polyadenylation pre-initiation complex, we examined their function in vivo and in vitro . We show that the upstream AU-rich region can function in the absence of the consensus hexanucleotide sequence both in vivo and in vitro and that both GU-rich regions are necessary for full polyadenylation activity in vivo and for formation of polyadenylation-specific complexes in vitro . Sequence comparisons reveal that: (i) the dual structure is distinct for the IgM secretory poly(A) site compared with other immunoglobulin isotype secretory poly(A) sites; (ii) the presence of an AU-rich region close to the consensus hexanucleotide is evolutionarily conserved for IgM secretory poly(A) sites. We propose that the dual structure of the IgM secretory poly(A) site provides a flexibility to accommodate changes in polyadenylation complex components during regulation of polyadenylation efficiency.