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5-Lipoxygenase (5-LO) catalysis is positively regulated by Ca2+ ions and phospholipids that both act via the N-terminal C2-like domain of 5-LO. Previously, we have shown that 1-oleoyl-2-acetylglycerol (OAG) functions as an agonist for human polymorphonuclear leukocytes (PMNL) in stimulating 5-LO product formation. Here we have demonstrated that OAG directly stimulates 5-LO catalysis in vitro. In the absence of Ca2+ (chelated using EDTA), OAG strongly and concentration-dependently stimulated crude 5-LO in 100,000 x g supernatants as well as purified 5-LO enzyme from PMNL. Also, the monoglyceride 1-O-oleyl-rac-glycerol and 1,2-dioctanoyl-sn-glycerol were effective, whereas various phospholipids did not stimulate 5-LO. However, in the presence of Ca2+, OAG caused no stimulation of 5-LO. Also, phospholipids or cellular membranes abolished the effects of OAG. As found previously for Ca2+, OAG renders 5-LO activity resistant against inhibition by glutathione peroxidase activity, and this effect of OAG is reversed by phospholipids. Intriguingly, a 5-LO mutant lacking tryptophan residues (Trp-13, -75, and -102) important for the binding of the 5-LO C2-like domain to phospholipids was not stimulated by OAG. We conclude that OAG directly stimulates 5-LO by acting at a phospholipid binding site located within the C2-like domain.
An account of the bryological activities on the Azores is given. Three phases can be distinguished: one at the end of the 19. century, when first collections of non-bryologists were made, which resulted in the discovery of less than one third of the presently known species and the description of many so called endemics. A second phase in the thirties of the 20. century is characterized by an intensive collecting activity of some bryologists, which enormously raised the species numbers. In a third phase at the end of the 20. century, tourism as well as activities of local bryologists raised again the species numbers. Revisions of genera reduced the number of endemic species and revisions of herbarium specimens of doubtful records even reduced the species numbers of hepatics.
A bryophyte checklist of the Ecological Reserve of Gurjaú (08º10’00'’-08º15’00"S; 35º02’30"- 35º05’00"W), a remnant of the Atlantic Forest in the State of Pernambuco, has been compiled. The Reserve covers an area of approximately 1362 ha, including several forest fragments of diverse sizes and stages of conservation. Specimens collected during the years 2000 and 2001, and voucher specimens from the UFP Herbarium at the Federal University of Pernambuco (UFPE) were analyzed. Bryophytes were collected on live and dead trunks, rocks, leaves and soil. The studied bryoflora is composed of 53 species of liverworts, 37 species of mosses and one hornwort. Among the twenty-three registered families, Lejeuneaceae (41 spp.) was the most representative one with the highest generic and specific richness, which confirms its status as predominant in tropical rain forests. Fissidens (7 spp.), Lejeunea and Cheilolejeunea (6 spp.), and Calymperes (4 spp.) were the most representative genera. The studied bryoflora is predominantly composed of species of neotropical distribution, widely spread throughout Brazil. The presence of an endemic species of the Atlantic Forest, Vitalianthus bichlerianus (Pôrto & Grolle) Schust. & Giancotti, and some other exclusively Brazilian species, e.g., Riccardia regnellii (Ängstr.) Hell have been recorded from the site.
The Distrito Federal, one of the most important centers of plant endemism in central Brazil, is located in the center of Brazil, with an area of 5,814 km2 at coordinates 15o30’ S, 16o03’W. Cerrado vegetation covers the region. The main city in the Distrito Federal is Brasília, the capital of Brazil with a population of 2.5 million. In the last two decades the anthropogenic action has reduced the original plant cover drastically. In this paper a checklist of the bryophytes (Marchantiophyta, Bryophyta and Anthocerotophyta) is presented. A total of 176 species are listed, 114 among Bryophyta, 61 among Marchantiophyta and 1 in the Anthocerotophyta. The families best represented are the Bryaceae and Sematophyllaceae (Bryophyta), and the Jubulaceae and Lejeuneaceae (Marchantiophya).
The study offers a discourse-based account of the Spanish copula forms ser and estar, which are generally considered to be lexical exponents of the stage-level/individual-level contrast. It argues against the popular view that the distinction between SLPs and ILPs rests on a fundamental cognitive division of the world that is reflected in the grammar. As it happens, conceptual oppositions like “temporary vs. permanent” or “arbitrary vs. essential“ provide only a preference for the interpretation of estar and ser. In addition, the evidence for an SLP/ILP impact on the grammar turns out to be far less conclusive than is currently assumed. The study argues against event-based accounts of the ser/estar contrast in particular, showing that ser and estar pattern alike in failing all of the standard eventuality tests. The discourse-based account proposed instead assumes that ser and estar both display the same lexical semantics (which is identical to the semantics of English be, German sein, etc.); estar differs from ser only in presupposing a relation to a specific discourse situation. By using estar a speaker restricts his or her claim to a specific discourse situation, whereas by using ser, the speaker makes no such restriction. The preference for interpreting estar predications as denoting temporary properties and ser predications as denoting permanent properties follows from economy principles driving the pragmatic legitimation of estars discourse dependence. The analysis proposed in this paper can also account for the observation that ser predications do not give rise to thetic judgements. The proposal is couched in terms of the framework of DRT.