Somatostatin inhibition of insulin release from freshly isolated and organ cultured rat islets of langerhans in vitro

1×10^?6M somatostatin causes a 37–44% inhibition of glucose induced insulin release from freshly isolated rat islets of Langerhans. A 81 to 95% inhibition is observed when the isolated islets are maintained in organ culture for 2 days prior to the somatostatin treatment. The dose curve of somatostatin on cultured islets shows an apparent K_I of 1.4×10^?9. The tetradecapeptide also causes a reversible inhibition of the stimulation of insulin release by 5 mM theophylline and 23 mM K⁺.     

Internal ribosome entry site structural motifs conserved among mammalian fibroblast growth factor 1 alternatively spliced mRNAs

Fibroblast growth factor 1 (FGF-1) is a powerful angiogenic factor whose gene structure contains four promoters, giving rise to a process of alternative splicing resulting in four mRNAs with alternative 5' untranslated regions (5' UTRs). Here we have identified, by using double luciferase bicistronic vectors, the presence of internal ribosome entry sites (IRESs) in the human FGF-1 5' UTRs, particularly in leaders A and C, with distinct activities in mammalian cells. DNA electrotransfer in mouse muscle revealed that the IRES present in the FGF-1 leader A has a high activity in vivo. We have developed a new regulatable TET OFF bicistronic system, which allowed us to rule out the possibility of any cryptic promoter in the FGF-1 leaders. FGF-1 IRESs A and C, which were mapped in fragments of 118 and 103 nucleotides, respectively, are flexible in regard to the position of the initiation codon, making them interesting from a biotechnological point of view. Furthermore, we show that FGF-1 IRESs A of murine and human origins show similar IRES activity profiles. Enzymatic and chemical probing of the FGF-1 IRES A RNA revealed a structural domain conserved among mammals at both the nucleotide sequence and RNA structure levels. The functional role of this structural motif has been demonstrated by point mutagenesis, including compensatory mutations. These data favor an important role of IRESs in the control of FGF-1 expression and provide a new IRES structural motif that could help IRES prediction in 5' UTR databases.     

Severe abnormalities in the oral mucosa induced by suprabasal expression of epidermal keratin K10 in transgenic mice

Previous studies have demonstrated that keratin K10 plays an important role in mediating cell signaling processes, since the ectopic expression of this keratin induces cell cycle arrest in proliferating cells in vitro and in vivo. However, apart from its well known function of providing epithelial cells with resilience to mechanical trauma, little is known about its possible roles in nondividing cells. To investigate what these might be, transgenic mice were generated in which the expression of K10 was driven by bovine K6beta gene control elements (bK6(beta)hK10). The transgenic mice displayed severe abnormalities in the tongue and palate but not in other K6-expressing cells such as those of the esophagus, nails, and hair follicles. The lesions in the tongue and palate included the cytolysis of epithelial suprabasal cells associated with an acute inflammatory response and lymphocyte infiltration. The alterations in the oral mucosa caused the death of transgenic pups soon after birth, probably because suckling was impaired. These anomalies, together with others found in the teeth, are reminiscent of the lesions observed in some patients with pachyonychia congenita, an inherited epithelial fragility associated with mutations in keratins K6 and K16. Although no epithelial fragility was observed in the bK6(beta)hK10 oral epithelia of the experimental mice, necrotic processes were seen. Collectively, these data show that the carefully regulated tissue- and differentiation-specific patterns displayed by the keratin genes have dramatic consequences on the biological behavior of epithelial cells and that changes in the specific composition of the keratin intermediate filament cytoskeleton can affect their physiology, in particular those of the oral mucosa.     

Parasitism in Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) by Encarsia hispida De Santis (Hymenoptera: Aphelinidae), in papaya, in Brazil

Infestation of Trialeurodes variabilis (Quaintance) was observed in October 2004, in papaya plants of cultivar Sunrise Solo, under screenhouse conditions, in Cruz das Almas, State of Bahia, Brazil. In infested leaves, around 20% of parasitism on nymphs was verified. Leaves with parasitized nymphs were kept in laboratory until emergence of the parasitoid, identified as Encarsia hispida De Santis. This is the first time that this parasitoid was detected on T. variabilis nymphs in Brazil.     

Effect of Cattle on Salmonella Carriage,Diversity and Antimicrobial Resistance in Free-Ranging Wild Boar (Sus scrofa) in Northeastern Spain

Salmonella is distributed worldwide and is a pathogen of economic and public health importance. As a multi-host pathogen with a long environmental persistence, it is a suitable model for the study of wildlife-livestock interactions. In this work, we aim to explore the spill-over of Salmonella between free-ranging wild boar and livestock in a protected natural area in NE Spain and the presence of antimicrobial resistance. Salmonella prevalence, serotypes and diversity were compared between wild boars, sympatric cattle and wild boars from cattle-free areas. The effect of age, sex, cattle presence and cattle herd size on Salmonella probability of infection in wild boars was explored by means of Generalized Linear Models and a model selection based on the Akaike’s Information Criterion. Prevalence was higher in wild boars co-habiting with cattle (35.67%, CI 95% 28.19–43.70) than in wild boar from cattle-free areas (17.54%, CI 95% 8.74–29.91). Probability of a wild boar being a Salmonella carrier increased with cattle herd size but decreased with the host age. Serotypes Meleagridis, Anatum and Othmarschen were isolated concurrently from cattle and sympatric wild boars. Apart from serotypes shared with cattle, wild boars appear to have their own serotypes, which are also found in wild boars from cattle-free areas (Enteritidis, Mikawasima, 4:b:- and 35:r:z35). Serotype richness (diversity) was higher in wild boars co-habiting with cattle, but evenness was not altered by the introduction of serotypes from cattle. The finding of a S. Mbandaka strain resistant to sulfamethoxazole, streptomycin and chloramphenicol and a S. Enteritidis strain resistant to ciprofloxacin and nalidixic acid in wild boars is cause for public health concern.     

Hypolipidemic and antiatherosclerotic potential of Pleurotus ostreatus, cultived by submerged fermentation in the high-fat diet fed rats

The ability of Pleurotus ostreatus biomass, cultived by submerged fermentation, to produce beneficial effect on lipid profile and macrophages activity during a high-fat diet (HFD) for a long-term intake was investigated. Blood samples were collected through cardiac puncture to measure the plasma cholesterol, triglycerides, low-density protein (LDL), high-density protein (HDL), aspartate aminotransferase (AST) activity, urea-blood urea nitrogen (BUN)/creatinine ratio of rats fed on an HFD for 4 months. Dosage of lipid hydroperoxides was carried out on methanolic extract of liver tissue. Peritoneal macrophages activity was evaluated in relation to the superoxide anion, hydrogen peroxide and nitric oxide production, phagocytosis and lysosomal volume. The administration of P. ostreatus significantly altered the lipid profile and oxidative stress as related to the LDL and triglycerides decrease and inhibitory effects on superoxide anion and hydrogen peroxide production. All findings of this study lead us to suggest that the P. ostreatus maybe a beneficial agent in the hyperlipidemia and atherosclerosis treatments.     

Permeability of three boreal forest landscape types to bird movements as determined from experimental translocations

Efficient dispersal is critical to metapopulation persistence in fragmented landscapes. Yet, this phenomenon is poorly understood because it is difficult to study. We used an indirect method, experimental translocation, to investigate the permeability of three landscape types of the boreal mixedwood forest region of Canada to movements of a forest specialist, the ovenbird (Seiurus aurocapillus), and a habitat generalist, the white-throated sparrow (Zonotrichia albicollis). We captured a total of 148 males (84 ovenbirds; 64 sparrows), which were then colour banded and displaced ca. 2 km away from their territories in landscapes fragmented either by agriculture, timber harvesting, or natural disturbances. We measured the probability and time of return of individuals to their territories during the 48 h following their translocation. We examined the relative influence of landscape type, territory quality, and age, physical characteristics, and pairing status of individuals on their probability or time of return. For both species, landscape type was the only significant predictor of the probability and time of return of individuals. For the ovenbird, the agricultural landscape was least permeable, followed by the harvested and naturally patchy landscapes. The agricultural and harvested landscapes were equally permeable to white-throated sparrow movements, and the naturally patchy landscape was the least permeable. Permeability to ovenbird movements increased with the proportion of forest in the landscape. Because matrix type and the proportion and configuration of forest differed significantly among the three landscape types, we could not determine their relative influence on landscape permeability to bird movements. However, our results do indicate that even a long-distance migrant such as the ovenbird can move more rapidly and efficiently across the landscape as the proportion of suitable (or permeable) habitat increases.