Obtention de I-D-ribofuranosylade´nines

The I-D-ribosyladenines have been obtained by treatment of 5-amino-4-cyanoimidazole (N-substituted or not) with ethyl N-(2,3-O-isopropylidene-D-ribofuranosyl)formimidate. The anomeric mixtures of the corresponding O-isoprophylidene nucleoside have been separated and the anomer fully characterized. In neutral aqueous medium, these compounds are transformed into an anomeric mixture of the corresponding 6-D-ribofuranosyladenine. In basic medium, however, anomerisation of the starting compounds to give an α,β equilibrium, in which the α anomer preponderates, takes place.     

Botanical origin of honey from south of Calde´n district (Argentina)

We performed palynological analysis of 75 honey samples from the south of Caldén district, which is the part of the phytogeographical province del Espinal. Prosopis caldenia , "caldén" (Fabaceae) is the dominant arboreal species in this region. 79 pollen types that belong to 36 plant families were identified. Honeydew elements are absent or present in negligible amounts. Native flora is intensely utilized. Main nectar sources that characterize monofloral honey samples, are these natives Condalia microphylla (Rhamnaceae), Prosopis sp. and Vicia sp. (Fabaceae), Larrea divaricata (Zygophyllaceae) and Brassicaceae, which are foreign to the area. The pollen from these plants along with the pollen of Trichocline sp. (Asteraceae) and Prosopidastrum globosum (Fabaceae), Schinus fasciculatus (Anacardiaceae), Astereae and Lycium sp.(Solanaceae), characterize honey from Caldén.     

Cryptic dioecy and leaky dioecy in endemic species of Dombeya (Sterculiaceae) on La Re´union

The high frequency of dioecy on oceanic islands such as Hawaii and New Zealand has attracted a great deal of attention from plant evolutionary biologists. One reason suggested for the high prevalence of dioecy on oceanic islands is that taxa considered truly dioecious may have occasional hermaphrodite flowers, i.e., show leaky dioecy. In this study, we quantified the presence and distribution of leaky dioecy in a group of congeneric endemic species of the genus Dombeya (Sterculiaceae) on La Re´union island (Indian Ocean). All eight species show cryptic dioecy. Five species show strict dioecy and three species show leaky dioecy due to the presence of male trees that set fruit. Species with strict dioecy and large populations tend to occur in mid- to high-altitude moist tropical cloud forest, whereas species in smaller populations at lower altitude and in semidry tropical forest tend to show leaky dioecy. Two reasons for this differential distribution of strict dioecy and leaky dioecy are discussed. First, environmental variation along the altitudinal gradient, biotic and/or abiotic, may influence the breeding system. Second, leaky dioecy may be favored in lowland populations due to the small size and disturbed nature of such populations.     

Threatened species, a re-evaluation of the status of eight endemic plants of the Gala´pagos

Although still in relatively good condition, the Gala´pagos Archipelago suffers from increasing human pressures. Apart from direct actions like hunting and logging, endemic plants and animals are threatened by introduced species, and in many cases the present status of the populations is not known. The conservation status of eight plant species considered endangered was studied from literature and field surveys and the main threats were determined. Each of the eight species is endemic to only one island but in some cases is also present on nearby islets. Of these eight species, one is considered extinct, one critically endangered, and the others suffer various levels of threat. As in all island systems of the world, the main threats are introduced organisms, both plants and animals. The extinct species probably disappeared owing to invasion by Lantana camara, one of the most aggressively invasive plants of the islands, and the most endangered species is threatened by goats. The remaining species seem to be regenerating well and we can expect positive results from protection efforts. Today, only one of the eight species benefits from a direct protection action.     

Use of 5´-anchored primers for the enhanced recovery of specific microsatellite markers in Brassica napus L.

Microsatellite markers have assumed great significance in biological research. The isolation and characterisation of microsatellites involves DNA library construction and screening, DNA sequencing, primer design and PCR optimisation. When a microsatellite is situated close to the beginning or end of a cloned fragment, specific primers cannot be designed for one of the flanking sequences, thus hindering the utilisation of such microsatellites as markers. The present approach was to use one 5′-anchored primer complementary to the microsatellite sequence in combination with one specific Cy5- labelled primer with a view to retrieving useful microsatellites, which would otherwise be lost. Six pairs of a 5′ anchored primer and a specific primer were used across a set of 31 Brassica napus winter cultivars and one accession each of five additional Brassica species. Using laser fluorometry a single labelled product was observed after amplification with each of four primer pairs, and one primer pair gave two labelled products. Three products corresponded in size with the products expected if 5′ anchoring was effective, indicating the amplification of locus-specific full-length products including all of the microsatellite repeats. All six primer pairs showed polymorphisms across the Brassica species examined, but only one primer pair showed polymorphisms within B. napus, making it useful for genetic analysis in rapeseed cultivars. The other primer pairs could be useful in studying gene introgression into B. napus or for investigating interspecific crosses involving different Brassica species. Received: 5 August 1999 / Accepted: 1 November 1999     

A chloroplastic RNA ligase activity analogous to the bacterial and archaeal 2´-5' RNA ligase

Bacteria and archaea contain a 2'-5' RNA ligase that seals in vitro 2',3'-cyclic phosphodiester and 5'-hydroxyl RNA termini, generating a 2',5'-phosphodiester bond. In our search for an RNA ligase able to circularize the monomeric linear replication intermediates of viroids belonging to the family Avsunviroidae, which replicate in the chloroplast, we have identified in spinach (Spinacea oleracea L.) chloroplasts a new RNA ligase activity whose properties resemble those of the bacterial and archaeal 2'-5' RNA ligase. The spinach chloroplastic RNA ligase recognizes the 5'-hydroxyl and 2',3'-cyclic phosphodiester termini of Avocado sunblotch viroid and Eggplant latent viroid RNAs produced by hammerhead-mediated self-cleavage, yielding circular products linked through an atypical, most likely 2',5'-phosphodiester, bond. The enzyme neither requires divalent cations as cofactors, nor NTPs as substrate. The reaction apparently reaches equilibrium at a low ratio between the final circular product and the linear initial substrate. Even if its involvement in viroid replication seems unlikely, the identification of a 2'-5' RNA ligase activity in higher plant chloroplasts, with properties very similar to an analogous enzyme widely distributed in bacterial and archaeal proteomes, is intriguing and suggests an important biological role so far unknown.     

Permanent night workers´ sleep and psychosocial factors in hospital work. A comparison to day and shift work

ABSTRACT

We aimed to study whether permanent night workers sleep and psychosocial factors differ from day workers and shift workers. The participants (n = 9 312, 92% females, average age 45 years, most commonly nurses and departmental secretaries) were day workers (DW, n = 2 672), shift workers (SW, n = 6 486) and permanent night workers (PNW, n = 154). The Finnish Public Sector survey responses from six hospital districts from 2012 were combined to payroll data from 91 days preceding the survey. The data were analyzed using Pearson χ²-test, one-way ANOVA and multinomial logistic regression analysis. The PNWs reported slightly longer average sleep length than the SWs or the DWs (7:27 vs. 7:13 and 7:10 h, p < 0.001). The PNWs reported least often difficulties in maintaining sleep (p < 0.001) compared to the SWs and the DWs. The PNWs reported most often difficulties to fall asleep and fatigue during free-time (p-values <0.001). The DWs and PNWs experienced less often work-life conflict than the SWs (25 and 26 vs. 38%, p < 0.001). The PNWs were more often satisfied with autonomy at work and appreciation and fair treatment by colleagues than the DWs or the SWs (p < 0.001). The SWs and PNWs reported remarkably higher occurrence of verbal (p < 0.001, OR 3.71, 95% CI 3.23–4.27 and OR 7.67, 95% CI 5.35–10.99, respectively) and physical workplace violence (p < 0.001, OR 9.24, 95% CI 7.17–11.90 and OR 28.34, 95% CI 16.64–43.06, respectively) compared to DWs. Conclusively, PNWs reported contradictory differences in sleep quality compared to DWs and SWs. PNWs are more often satisfied with their colleagues and autonomy at work than DWs or SWs but face workplace violence remarkably more often.     

A novel fibrinolytic metalloproteinase,barnettlysin-I from Bothrops barnetti (barnett´s pitviper) snake venom with anti-platelet properties

BackgroundViperid snake venoms contain active components that interfere with hemostasis. We report a new P-I class snake venom metalloproteinase (SVMP), barnettlysin-I (Bar-I), isolated from the venom of Bothrops barnetti and evaluated its fibrinolytic and antithrombotic potential.MethodsBar-I was purified using a combination of molecular exclusion and cation-exchange chromatographies. We describe some biochemical features of Bar-I associated with its effects on hemostasis and platelet function.ResultsBar-I is a 23.386 kDa single-chain polypeptide with pI of 6.7. Its sequence (202 residues) shows high homology to other members of the SVMPs. The enzymatic activity on dimethylcasein (DMC) is inhibited by metalloproteinase inhibitors e.g. EDTA, and by α2-macroglobulin. Bar-I degrades fibrin and fibrinogen dose- and time-dependently by cleaving their α-chains. Furthermore, it hydrolyses plasma fibronectin but not laminin nor collagen type I. In vitro Bar-I dissolves fibrin clots made either from purified fibrinogen or from whole blood. In contrast to many other P-I SVMPs, Bar-I is devoid of hemorrhagic activity. Also, Bar-I dose- and time-dependently inhibits aggregation of washed human platelets induced by vWF plus ristocetin and collagen (IC₅₀ = 1.3 and 3.2 μM, respectively), presumably Bar-I cleaves both vWF and GPIb. Thus, it effectively inhibits vWF-induced platelet aggregation. Moreover, this proteinase cleaves the collagen-binding α2-A domain (160 kDa) of α2β1-integrin. This explains why it additionally inhibits collagen-induced platelet activation.ConclusionA non-hemorrhagic but fibrinolytic metalloproteinase dissolves fibrin clots in vitro and impairs platelet function.General significanceThis study provides new opportunities for drug development of a fibrinolytic agent with antithrombotic effect.     

Purification and characterisation of the dimeric group 12 allergen from Blomia tropicalis heterologously expressed by Escherichia coli Top10F´

Successful research in the wide-ranging field of allergy is usually achieved by definition not only of physicochemical and immunological properties of natural, but also recombinant allergens. Blomia tropicalis mite is a well-known source for various groups of hypersensitivity-causing proteins. The goal of the present work was to produce, purify and characterise by in silico, biochemical and immunological methods the recombinant group-12 allergen of B. tropicalis. The recombinant Blo t 12 aggregation capacity as well as the affinity to antibodies from BALB/c immunised mice and B. tropicalis-sensitised human donors were investigated through in silico analyses, dynamic light scattering, SDS-PAGE, ELISA and Western blot. The presence of Blo t 12 within B. tropicalis extracts was also determined by ELISA and Western blot. High concentrations of dimeric rBlo t 12 were detected through SDS-PAGE next to other aggregates and the results were confirmed by data from DLS and Western blot. The YITVM peptide was predicted to be the most aggregation-prone region. The IgE-reactivity of rBlo t 12 was not completely abolished by aggregate formation but it was significantly decreased compared to rBlo t 5, or B. tropicalis extracts. Natural Blo t 12 may naturally dimerises, but it was detected in non-delipidified B. tropicalis extracts in low amounts. Given that this allergen may be a specific marker for B. tropicalis allergy, the recombinant Blo t 12 herein obtained is characterised as a mid-tier allergen in Brazilian atopic patients and may be useful for the improvement in precision allergy molecular diagnostic applications.

     

Biodiversity,science and development. Towards a new partnership. Edited by F. di Castri and T. Youne´s

World Journal of Microbiology and Biotechnology -