Seed lectin from pisum arvense: isolation, biochemical characterization and amino acid sequence

A glucose/mannose lectin was purified by affinity chromatography from Pisum arvense seeds (PAL) and the 50 kDa molecular mass in solution determined by size exclusion chromatography. SDS-PAGE and electrospray ionization mass spectrometry showed two distinct polypeptide chains: alpha (Mr. 5591 Da) and beta (19986 Da). The lectin was extensively characterized in terms of its biochemical and biological aspects. The amino acid sequence was established by Edman degradation of overlapping peptides. PAL in solution behaves as a dimer and has its monomeric structure formed by two distinct polypeptide chains named alpha (Mr. 5591 Da) and beta (19986 Da) by Electrospray ionization (ESI) mass spectrometry. PAL possesses identical amino acid sequences to that of pea seed lectin but undoubtedly does not exhibit sequence heterogeneity. It is discussed that P. arvense should be considered as a synonym of P. sativum. Furthermore, like pea lectin, PAL discriminates biantennary fucosylated glycan, determined by surface plasmon resonance.     

Antimicrobial compounds of fungi vectored by Clusia spp. (Clusiaceae) pollinating bees

The production of antimicrobial compounds by fungi associated with Clusia spp. pollinating bees (Trigona sp., Trigonini) was investigated in order to approach natural mechanisms of microbial density control within nest environment. By using a bioassay-guided approach based on bioautography and minimal inhibitory concentration (MIC), known alpha,beta-dehydrocurvularin and curvularin were isolated from Curvularia eragrostidis (CCT 5634) and Curvularia pallescens (CCT 5654), and known cochlioquinone A and isocochlioquinone A were isolated from Drechslera dematioidea (CCT 5631).     

Quantitative determination of anti-fungal and insecticide amides in adult plants, plantlets and callus from Piper tuberculatum by reverse-phase high-performance liquid chromatography

A rapid, sensitive and reliable reverse-phase HPLC method was used for the quantitative determination of the anti-fungal and insecticide amides, dihydropiplartine (1), piplartine (2), deltaalpha,beta-dihydropiperine (3) and pellitorine (4) in plants in natura, in plantlets in vitro and ex vitro, and in callus of Piper tuberculatum. Well-resolved peaks were obtained with good detection response and linearity in the range of 15.0-3000 microg/mL. The plants in natura contained compounds 1-4, the plantlets ex vitro and in vitro accumulated compounds 1-2 and 1-4, respectively, while only amide 4 was found in callus.     

Distribution patterns of benthic diatoms in a Pampean river exposed to seasonal floods: the Cuarto River (Argentina)

The diatom community growing on cobbles and sand substrata along the Cuarto River (Córdoba, Argentina) was studied during 2000 and 2001. Multivariate analyses of the data (PCA and CCA) showed distinct differences in water chemistry and substrata types between the upstream sites (sites 1–10) and downstream sites (sites 11–19). Sites 1–10 supported an epilithic diatom community associated with low water conductivity and gravel substrata. This consisted of adnate Achnanthes (A. biasolettiana, A. minutissima), as well as stalked (Gomphonema aff. angustum, Reimeria uniseriata, Fragilaria capucina var. rumpens) or prostrate (Nitzschia lacuum) taxa. Downstream sites were associated with high conductivity, fast flowing waters and finer substrata (sand, silt), and were colonised by prostrate diatoms, including several species of Navicula (N. pupula, N. mutica, N. veneta, N. insociabilis) and Nitzschia (N. umbonata, N. palea). Variations in water flow caused significant changes in the diatom communities of the river. During periods of low flow (winter and autumn), chain forming (Diatoma vulgaris, D. moniliformis) or stalked (Synedra ulna) taxa partially replaced the former community of Navicula and Nitzschia in the downstream sites. High flow (in summer) led to diatoms of large size being replaced by smaller size diatoms, such as Achnanthes lanceolata, Navicula mutica, Hantzschia amphioxys and Amphora montana. The severe effect of floods in the lower part of the Cuarto led to these taxa having a much higher proportion in the lower stretch of the river, taking advantage of the subaerial conditions created by the floods. Local episodes of water pollution were associated with a transient shift towards the dominance of Navicula pupula, Synedra ulna, Nitzschia lacuum and Reimeria uniseriata during winter, when inputs were least diluted because of the low flow.     

Radioactivity as a Significant Energy Source in Prebiotic Synthesis

Radioactivity in the continental crust (due mainly to the isotopes ²³⁸U,²³⁵U, ²³²Th and ⁴⁰K), as a energysource for chemical evolution in the early Archean (between 3.5 and 4 Ga bp), is reviewed.The most important radioactive sourcein the continental crust is due to theproduction and accumulation of radioactivegases within the crust voids (porosity). Thestudy of such mechanism has allowed us toreach a deeper understanding about the nature of the radioactive source and to describe itsbehavior, particularly with regard to prebiotic chemical evolution. An effectivetotal energy of 3 × 10^{18 Ja -1} hasbeen obtained for a depth of 1 km, 4 Ga ago. If a depth of 30 km is taken, the obtained valueis almost equal to the UV solar energyradiation (<150 nm). Within thevoids the radioactive source of thecontinental crust played a relevant role inprebiotic synthesis. In uraniumdeposits of the same age, the role ofradiactivity must have been even more relevantin favoring chemical evolution.     

In vitro antifungal activities of voriconazole and reference agents as determined by NCCLS methods: Review of the literature

Voriconazole (Vfend™) is a new triazole that currently is undergoing phase III clinical trials. This review summarizes the published data obtained by NCCLS methods on the in vitro antifungal activity of voriconazole in comparison to itraconazole, amphotericin B, fluconazole, ketoconazole and flucytosine. Voriconazole had fungistatic activity against most yeasts and yeastlike species (minimum inhibitory concentrations [MICs] <2 μg/ml) that was similar or superior to those of fluconazole, amphotericin B, and itraconazole. Against Candida glabrata and C. krusei, voriconazole MIC ranges were 0.03 to 8 and 0.01 to >4 μg/ml, respectively. For four of the six Aspergillus spp. evaluated, voriconazole MICs (< 0.03 to 2 μg/ml) were lower than amphotericin B (0.25 to 4 μg/ml) and similar to itraconazole MICs. Voriconazole fungistatic activity against Fusarium spp. has been variable. Against F. oxysporum and solani, most studies showed MICs ranging from 0.25 to 8 μg/ml. Voriconazole had excellent fungistatic activity against five of the six species of dimorphic fungi evaluated (MIC₉₀s < 1.0 μg/ml). The exception was Sporothrix schenckii (MIC₉₀s and geometric mean MICs ≥ 8 μg/ml). Only amphotericin B had good fungistatic activity against the Zygomycetes species (voriconazole MICs ranged from 2 to >32 μg/ml). Voriconazole showed excellent in vitro activity (MICs < 0.03 to 1.0 μg/ml) against most of the 50 species of dematiaceous fungi tested, but the activity of all the agents was poor against most isolates of Scedosporium prolificans and Phaeoacremonium parasiticum (Phialophora parasitica). Voriconazole had fungicidal activity against most Aspergillus spp., B. dermatitidis, and some dematiaceous fungi. In vitro/in vivo correlations should aid in the interpretation of these results. This revised version was published online in June 2006 with corrections to the Cover Date.     

Age and growth,reproduction and diet of a sublittoral population of the rock goby Gobius paganellus (Teleostei,Gobiidae)

Colonisation of extremely acidic waters (pH 3) by aquatic angiosperms occurs widely, but is poorly documented. Unlike acid rain affected and other naturally acidic aquatic ecosystems, waters with pH 3 usually have a high conductivity, with high concentrations of SO₄ ^2- and often high concentrations of Fe³⁺, other heavy metal ions and Al³⁺. Where Fe³⁺ concentration is high, as in many mine waters, it provides a strong buffering system. In such waters, the biogeochemical Fe cycle exerts over water chemistry and the availability of nutrients and carbon for organisms. Biological activity is limited by low concentrations of phosphorus and inorganic carbon (DIC), which in this pH range is essentially all in the form of dissolved CO₂. A number of angiosperms grow in such waters including Phragmites australis, Typha spp. and Juncus bulbosus, though the last is the only one reported to grow totally submerged in waters with pH 3 . J. bulbosus occurs in many lignite mining lakes in Lusatia (north eastern Germany) with pH 3. The characteristics and possible survival strategies for this and other species are discussed.