Chemical Composition of Two Exopolysaccharides from Bacillus thermoantarcticus

The thermophilic bacterium Bacillus thermoantarcticus produces two exocellular polysaccharides (EPS 1 and EPS 2), which can be obtained from the supernatant of liquid cultures by cold-ethanol precipitation, in yields as high as 400 mg liter(sup-1). The EPS fraction was produced with all substrates tested, although a higher yield was obtained with mannose as the carbon and energy source. The EPS content was proportional to the total biomass. On a weight basis, EPS 1 and EPS 2 represented about 27 and 71%, respectively, of the total carbohydrate fraction. EPS 1 is a sulfate heteropolysaccharide containing mannose and glucose in a relative molar proportion of 1.0 and 0.7, respectively. EPS 2 is a sulfate homopolysaccharide containing mannose as the major component. The absolute configurations of hexoses were shown to be d for both EPSs. Nuclear magnetic resonance spectra confirmed the presence of (alpha)-d-mannose and (beta)-d-glucose in EPS 1 and only (alpha)-d-mannose in EPS 2. In addition, (sup1)H nuclear magnetic resonance analysis and chemical analysis indicated the presence of pyruvic acid in EPS 2.     

A new platinum(II) compound anticancer drug candidate with selective cytotoxicity for breast cancer cells

[Pt(O,O′-acac)(γ-acac)(DMS)] (PtAcD) is able to induce apoptosis in various human cancer cells, including the cisplatin-resistant human breast carcinoma MCF-7 cells. Here, to confirm that PtAcD has the potentiality for therapeutic intervention, we studied its effects in primary cultured epithelial breast cells obtained from cancers and also from the corresponding histologically proven non-malignant tissue adjacent to the tumor. We demonstrated that PtAcD (1) is more cytotoxic in cancer than in normal breast cells; (2) activated NAD(P)H oxidase, leading to PKC-ζ and PKC-α tanslocations; (3) activated antiapoptotic pathways based on the PKC-α, ERK1/2 and Akt kinases; (4) activated PKC-ζ and, only in cancer cell PKC-δ, responsible for the sustained phosphorylation of p38 and JNK1/2, kinases both of which are involved in the mitochondrial apoptotic process. Moreover, crosstalk between ERK/Akt and JNK/p38 pathways affected cell death and survival in PtAcD-treated breast cell. In conclusion, this study adds and extends data that highlight the pharmacological potential of PtAcD as an anti breast cancer drug.     

Assembly mechanisms determining high species turnover in aquatic communities over regional and continental scales

Niche and neutral processes drive community assembly and metacommunity dynamics, but their relative importance might vary with the spatial scale. The contribution of niche processes is generally expected to increase with increasing spatial extent at a higher rate than that of neutral processes. However, the extent to what community composition is limited by dispersal (usually considered a neutral process) over increasing spatial scales might depend on the dispersal capacity of composing species. To investigate the mechanisms underlying the distribution and diversity of species known to have great powers of dispersal (hundreds of kilometres), we analysed the relative importance of niche processes and dispersal limitation in determining beta‐diversity patterns of aquatic plants and cladocerans over regional (up to 300 km) and continental (up to 3300 km) scales. Both taxonomic groups were surveyed in five different European regions and presented extremely high levels of beta‐diversity, both within and among regions. High beta‐diversity was primarily explained by species replacement (turnover) rather than differences in species richness (i.e. nestedness). Abiotic and biotic variables were the main drivers of community composition. Within some regions, small‐scale connectivity and the spatial configuration of sampled communities explained a significant, though smaller, fraction of compositional variation, particularly for aquatic plants. At continental scale (among regions), a significant fraction of compositional variation was explained by a combination of spatial effects (exclusive contribution of regions) and regionally‐structured environmental variables. Our results suggest that, although dispersal limitation might affect species composition in some regions, aquatic plant and cladoceran communities are not generally limited by dispersal at the regional scale (up to 300 km). Species sorting mediated by environmental variation might explain the high species turnover of aquatic plants and cladocerans at regional scale, while biogeographic processes enhanced by dispersal limitation among regions might determine the composition of regional biotas.     

The role of MmpL8 in sulfatide biogenesis and virulence of Mycobacterium tuberculosis

To study the role of MmpL8-mediated lipid transport in sulfatide biogenesis, we insertionally inactivated the mmpL8 gene in Mycobacterium tuberculosis. Characterization of this strain showed that the synthesis of mature sulfolipid SL-1 was interrupted and that a more polar sulfated molecule, termed SL-N, accumulated within the cell. Purification of SL-N and structural analysis identified this molecule as a family of 2,3-diacyl-alpha,alpha'-D-trehalose-2'-sulfates. This structure suggests that transport and biogenesis of SL-1 are coupled and that the final step in sulfatide biosynthesis may be the extra-cellular esterification of two trehalose 6-positions with hydroxyphthioceranic acids. To assess the effect of the loss of this anionic surface lipid on virulence, we infected mice via aerosol with the MmpL8 mutant and found that, although initial replication rates and containment levels were identical, compared with the wild type, a significant attenuation of the MmpL8 mutant strain in time-to-death was observed. Early in infection, differential expression of cytokines and cytokine receptors revealed that the mutant strain less efficiently suppresses key indicators of a Th1-type immune response, suggesting an immunomodulatory role for sulfatides in the pathogenesis of tuberculosis.     

Aspartate aminotransferase ofLactobacillus murinus

Aspartate aminotransferase from Lactobacillus murinus is thermostable, its activity being not changed for two months at temperatures between 4 and -70 degrees C. Maximum activity was observed at 40 degrees C and pH 7.3 in phosphate buffer (30 mmol/L). delta G* Value of 26.3 kJ/mol was calculated from the Arrhenius plot. The Km values for L-aspartate and 2-oxoglutarate at pH 7.3 were 25 and 100 mmol/L, respectively. Sodium maleate and glutamate acted as inhibitors of the enzyme activity. The Ki values for sodium maleate with L-aspartate of 2-oxoglutarate as variable substrates were 1.1 and 0.5 mmol/L, respectively. The Ki values for glutamate with L-aspartate or 2-oxoglutarate were 8.0 and 4.0 mmol/L, respectively. An inhibitory effect was observed with 1 mM Hg2+ ions (1 mmol/L). The activity of the enzyme was diminished by only 12% in the absence of pyridoxal 5'-phosphate.     

Electrophoretic and chromatographic evidence for allelic polymorphisms in the river buffalo α-globin gene complex

Isoelectric focusing in the ultranarrow immobilized (7.1–7.5) pH gradient (IPG) of hemoglobin and high-performances liquid chromatography (HPLC) of globin chains were used to investigate Hb polymorphism in Italian river buffalo. Six different phenotypes, each characterized by two or four different Hbs, were detected by IPG, whereas two different^IIα-globin chains were separated from two different^Iα-chains by HPLC. Two α-chains (^Iα¹ and^IIα³), and Hbs with similar mobilities (Hb1 andHb3), were associated with the AA Hb phenotype: two α-chains (^Iα² and^IIα⁴), and Hbs with different mobilities (Hb2 andHb4), were associated with the BB phenotype: two sets of doublet Hbs were associated with the AB phenotype, thus suggesting allelic polymorphisms at the two α loci. An allele at the β locus is responsible for increasing to as many as eight the number of different Hbs, thus further complicating the notable Hb polymorphism of the river buffalo.     

Arctotheca calendula (L.) Levyns: An emerging invasive species in Italy

Abstract

Prevention and early detection are considered to be the most effective means of managing non-native invasive species that have serious ecological and economic impacts. Consequently, the study of those taxa that are still in an early stage of invasion but are highly likely to spread and to have a significant adverse impact in future is becoming an increasingly important issue in both the research on and management of invasive species. In Italy, one such species is Arctotheca calendula (L.) Levyns, a herbaceous plant of the Asteraceae family that is native to South Africa. Here, we present an overview of current knowledge on the distribution and potential impacts of this species in Italy, and we outline some features that are crucial to understanding and preventing its invasive spread.