Phylogeographical pattern of Euplotes nobilii,a protist ciliate with a bipolar biogeographical distribution

Nuclear (18S and ITS) and mitochondrial (16S) ribosomal RNA gene sequences were determined from genetically distinct wild‐type strains of Antarctic (nine strains), Fuegian (four strains), Greenland (nine strains) and Svalbard (three strains) populations of the marine ciliate, Euplotes nobilii, and analysed for their nucleotide polymorphisms. A close genetic homogeneity was found within and between the Antarctic and Fuegian populations, while more significant levels of genetic differentiation were detected within and between the two Arctic populations, as well as between these populations and the Antarctic/Fuegian ones. The phylogeographical pattern that was derived from these data indicates that gene flow is not limited among Arctic populations; it equally connects the Arctic and Antarctic populations either directly, or through the Fuegian population. This indication reinforces previous evidence from laboratory assays of mating interactions between some of the strains analysed in this work that Southern and Northern polar populations of E. nobilii belong to a unique, panmictic population that substantially share the same gene pool.     

Different Permeability of Potassium Salts across the Blood-Brain Barrier Follows the Hofmeister Series

The passage of ions across biological membranes is regulated by passive and active mechanisms. Passive ion diffusion into organs depends on the ion-pairing properties of salts present in the serum. Potassium ions could affect brain activity by crossing the blood-brain barrier (BBB) and its accumulation in the extracellular cerebral space could precipitate seizures. In the present study, we analyze passive diffusion of a series of potassium salts in the in vitro isolated guinea pig brain preparation. Different potassium counter-anions confer ion-pairing and lipophilicity properties that modulate membrane diffusion of the salt. Extracellular recordings in different cortical areas demonstrated the presence of epileptiform activities that strongly relate to anion identity, following the qualitative order of the Hofmeister series. Indeed, highly lipophilic salts that easily cross the BBB enhanced extracellular potassium concentration measured by ion-selective electrodes and were the most effective pro-epileptic species. This study constitutes a novel contribution for the understanding of the potential epileptogenicity of potassium salts and, more generally, of the role of counter-anions in the passive passage of salts through biological membranes.     

Glucose Accelerates Copper- and Ceruloplasmin-induced Oxidation of Low-density Lipoprotein and Whole Serum

Glucose at pathophysiological concentrations was able to accelerate copper-induced oxidation of isolated low-density lipoprotein (LDL) and whole serum. The efficiency of glucose was favored under the following circumstances: (a) when LDL oxidation was induced by low copper concentration, (b) when LDL was partly oxidized, i.e. enriched with lipid peroxides. The glucose derivative methyl- &#102 - d -glucoside was ineffective on Cu 2+ -induced LDL oxidation, pointing out the essential role of the reactivity of the aldehydic carbon for the pro-oxidative effect. When LDL oxidation was induced by a peroxyl radical generator, as a model of transition metal independent oxidation, glucose was ineffective. Glucose was found to stimulate oxidation of LDL induced by ceruloplasmin, the major copper-containing protein of human plasma. Thus, glucose accelerated oxidation of LDL induced by both free and protein bound copper. Considering the requirement for catalytically active copper and for the aldehydic carbon, the pro-oxidative effect of glucose is likely to depend on the increased availability of Cu + ; this is more efficient in decomposing lipid peroxide than Cu 2+ , accounting for acceleration of LDL oxidation. The possible biological relevance of our work is supported by the finding that glucose was able to accelerate oxidation of whole serum, which was assessed by monitoring low-level chemiluminescence associated with lipid peroxidation.     

Recombinant near-isogenic lines: a resource for the mendelization of heterotic QTL in maize

Although heterosis is widely exploited in agriculture, a clear understanding of its genetic bases is still elusive. This work describes the development of maize recombinant near-isogenic lines (NILs) for the mendelization of six heterotic QTL previously identified based on a maize (Zea mays L.) RIL population. The efficient and inexpensive strategy adopted to generate sets of NILs starting from QTL-specific residual heterozygous lines (RHLs) is described and validated. In particular, we produced nine pairs of recombinant NILs for all six QTL starting from RHLs F_4:5 originally obtained during the production of the RIL population mentioned above. Whenever possible, two different NIL pairs were generated for each QTL. The efficiency of this procedure was tested by analyzing two segregating populations for two of the selected heterotic QTL for plant height, yield per plant and ears per plant. Both additive and dominant effects were observed, consistently with the presence of the QTL within the introgressed regions. Refinement of QTL detection was consistent with previous observations in terms of effects and position of the considered QTL. The genetic material developed in this work represents the starting point for QTL fine mapping aimed at understanding the genetic bases of hybrid vigor in maize. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Anoxybacillus thermarum sp. nov., a novel thermophilic bacterium isolated from thermal mud in Euganean hot springs, Abano Terme, Italy

A novel aerobe thermophilic endospore-forming bacterium designated strain AF/04^T was isolated from thermal mud located in Euganean hot springs, Abano Terme, Padova, Italy. Strain AF/04^T was Gram-positive, motile, rod-shaped, occurring in pairs, or filamentous. The isolate grew between 55 and 67°C (optimum 65°C) and at pH 6.0–7.5 (optimum pH 7.2). The strain was aerobic and grew on maltose, trehalose, and sodium acetate as sole carbon sources. The G + C content of DNA was 53.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain AF/04^T falls within the genus Anoxybacillus. Levels of 16S rRNA gene sequence similarity between strain AF/04^T and the type strains of recognized Anoxybacillus species ranged from 95 to 99%. Chemotaxonomic data (major isoprenoid quinone–menaquinone-7; major fatty acid iso-C15:0 and anteiso-C17:0) supported the affiliation of strain AF/04^T to the genus Anoxybacillus. Based on phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence analysis and DNA–DNA hybridization data, it was proposed that strain AF/04^T (=DSM 17141^T = ATCC BAA 1156^T) should be placed in the genus Anoxybacillus as the type strain of a novel species, Anoxybacillus thermarum sp. nov.     

Survival and Adaptation of the Thermophilic Species <Emphasis Type="Italic">Geobacillus thermantarcticus</Emphasis> in Simulated Spatial Conditions

Astrobiology studies the origin and evolution of life on Earth and in the universe. According to the panspermia theory, life on Earth could have emerged from bacterial species transported by meteorites, that were able to adapt and proliferate on our planet. Therefore, the study of extremophiles, i.e. bacterial species able to live in extreme terrestrial environments, can be relevant to Astrobiology studies. In this work we described the ability of the thermophilic species Geobacillus thermantarcticus to survive after exposition to simulated spatial conditions including temperature’s variation, desiccation, X-rays and UVC irradiation. The response to the exposition to the space conditions was assessed at a molecular level by studying the changes in the morphology, the lipid and protein patterns, the nucleic acids. G. thermantarcticus survived to the exposition to all the stressing conditions examined, since it was able to restart cellular growth in comparable levels to control experiments carried out in the optimal growth conditions. Survival was elicited by changing proteins and lipids distribution, and by protecting the DNA’s integrity.     

Characterization of the pheromone gene family of an Antarctic and Arctic protozoan ciliate, Euplotes nobilii

Allelic genes encoding water-borne signal proteins (pheromones) were amplified and sequenced from the somatic (macronuclear) sub-chromosomic genome of Antarctic and Arctic strains of the marine ciliate, Euplotes nobilii. Their open reading frames appeared to be specific for polypeptide sequences of 83 to 94 amino acids identifiable with cytoplasmic pheromone precursors (pre-pro-pheromones), requiring two proteolytic steps to remove the pre- and pro-segments and secrete the mature pheromones. Differently from most of the macronuclear genes that have so far been characterized from Euplotes and other hypotrich ciliates, the 5′ and 3′ non-coding regions of all the seven E. nobilii pheromone genes are much longer than the coding regions (621 to 700 versus 214 to 285 nucleotides), and the 5′ regions in particular show nearly identical sequences across the whole set of pheromone genes. These structural peculiarities of the non-coding regions are likely due to the presence of intron sequences and provide presumptive evidence that they are site of basic, conserved activities in the mechanism that regulates the expression of the E. nobilii pheromone genes.