High level synthesis of levan by a novel Halomonas species growing on defined media

A novel halophilic isolate from soil samples taken from Çamalt? Saltern area in Turkey, Halomonas sp. AAD6 (JCM 15723) strain, was found to produce high levels of exopolysaccharides (EPS), in the presence of sucrose in defined media, by flasks and bioreactor condition yielded 1.073 g L^?1 and 1.844 g L^?1, respectively. Sugar analysis, methylation studies and NMR analysis of EPS indicated the repeating unit of this polysaccharide was composed of β-(2,6)-d-fructofuranosyl residues. Hence with this work, Halomonas sp. has been described as a levan producer microorganism for the first time. Biocompatibility studies showed this EPS did not affect cellular viability and proliferation of osteoblasts and murine macrophages. The protective effect of the polymer against the toxic activity of avarol implied its additional use as an anti-cytotoxic agent. Halomonas sp. AAD6 could represent an alternative cheap source of levan polymer when grown on defined media hypothesizing its larger employment in industrial application being non pathogenic microorganism.     

Production and chemical characterization of an exopolysaccharide synthesized by psychrophilic yeast strain <Emphasis Type="Italic">Sporobolomyces salmonicolor</Emphasis> AL<Subscript>1</Subscript> isolated from Livingston Island,Antarctica

The exopolysaccharide (EPS) production by psychrophilic Antarctic yeast Sporobolomyces salmonicolor AL₁ reached the maximum yield in medium containing sucrose (50 g/L) and diammonium sulfate (2.5 g/L) after a 5-d fermentation (5.64 g/L) at 22 °C, the dynamic viscosity of the culture broth reaching (after 5 d) 15.4 mPa s. EPS showed a mannan-like structure and high molar mass, and did not affect cellular viability and proliferation of murine macrophages. It exhibited also a protective effect against the toxic activity of Avarol.     

Aberrant splicing in MLH1 and MSH2 due to exonic and intronic variants

Single base substitutions in DNA mismatch repair genes which are predicted to lead either to missense or silent mutations, or to intronic variants outside the highly conserved splicing region are often found in hereditary nonpolyposis colorectal cancer (HNPCC) families. In order to use the variants for predictive testing in persons at risk, their pathogenicity has to be evaluated. There is growing evidence that some substitutions have a detrimental influence on splicing. We examined 19 unclassified variants (UVs) detected in MSH2 or MLH1 genes in patients suspected of HNPCC for expression at RNA level. We demonstrate that 10 of the 19 UVs analyzed affect splicing. For example, the substitution MLH1,c.2103G>C in the last position of exon 18 does not result in a missense mutation as theoretically predicted (p.Gln701His), but leads to a complete loss of exon 18. The substitution MLH1,c.1038G>C (predicted effect p.Gln346His) leads to complete inactivation of the mutant allele by skipping of exons 10 and 11, and by activation of a cryptic intronic splice site. Similarly, the intronic variant MLH1,c.306+2dupT results in loss of exon 3 and a frameshift mutation due to a new splice donor site 5 bp upstream. Furthermore, we confirmed complete exon skipping for the mutations MLH1,c.1731G>A and MLH1,c.677G>A. Partial exon skipping was demonstrated for the mutations MSH2,c.1275A>G, MLH1,c.588+5G>A, MLH1,c.790+4A>G and MLH1,c.1984A>C. In contrast, five missense mutations (MSH2,c.4G>A, MSH2,c.2123T>A, MLH1,c.464T>G, MLH1,c.875T>C and MLH1,c.2210A>T) were found in similar proportions in the mRNA as in the genomic DNA. We conclude that the mRNA examination should precede functional tests at protein level. Databases: HNPCC – OMIM 114500, MSH2 – OMIM: 120435; GenBank: NM_000251.1, MLH1 – OMIM: 120436; GenBank: NM_000249.2, InSiGHT mutation database: , Programs: BDGP: , ESEfinder program:     

Resistance and bioaccumulation of Cd2+, Cu2+, Co2+ and Mn2+ by thermophilic bacteria, Geobacillus thermantarcticus and Anoxybacillus amylolyticus

In this study, bioaccumulation and heavy metal resistance of Cd²⁺, Cu²⁺, Co²⁺ and Mn²⁺ ions by thermophilic Geobacillus thermantarcticus and Anoxybacillus amylolyticus was investigated. The bacteria, in an order with respect to metal resistance from the most resistant to the most sensitive, was found to be Mn²⁺ > Co²⁺ > Cu²⁺ > Cd²⁺ for both G. thermantarcticus and A. amylolyticus. It was determined that the highest metal bioaccumulation was performed by A. amylolyticus in Mn²⁺ (28,566 μg/g dry weight), and the lowest metal bioaccumulation was performed by A. amylolyticus in Co²⁺ (327.3 μg/g dry weight). The highest Cd²⁺ capacities of dried cell membrane was found to be 36.07 and 39.55 mg/g membrane for G. thermantarticus and A. amylolyticus, respectively, and the highest Cd²⁺ capacities of wet cell membrane was found to be 14.36 and 12.39 mg/g membrane for G. thermantarcticus and A. amylolyticus, respectively.     

Comparison of Allogeneic Stem Cell Transplantation and Non-Transplant Approaches in Elderly Patients with Advanced Myelodysplastic Syndrome: Optimal Statistical Approaches and a Critical Appraisal of Clinical Results Using Non-Randomized Data

Allogeneic stem cell transplantation (ASCT) from related or unrelated donors may cure patients with myelodysplastic syndromes (MDS), a heterogeneous group of clonal stem cell disorders. We analysed 384 elderly patients (55-69 years) with advanced MDS who received either ASCT (n=247) and were reported to The European Group for Blood and Marrow Transplantation (EBMT) or a non –transplant approach (n=137) reported to the Düsseldorf registry. Besides an attempt to answer the question of „comparison“, the purpose of this work is to explain the difficulties in comparing a non-transplant with a transplant cohort, when death before transplant is likely but unknown and the selection of patients for transplant is based on assumptions. It shows which methods are almost always biased and that even the most sophisticated approaches crucially rely on clinical assumptions. Using the most appropriate model for our data, we derive an overall univariate non-significant survival disadvantage for the transplant cohort (HR: 1.29, p = 0.11). We show that such an “average” hazard ratio is however misleading due to non-proportionality of the hazards reflecting early treatment related mortality, the occurring of which is logically correlated with the interval between diagnosis and transplant creating a disproportional drop in the (reconstructed) survival curve of the transplanted patients. Also in multivariate analysis (correcting for age > 60 (HR: 1.4, p = 0.02) and abnormal cytogenetics (HR: 1.46, p = 0.01)), transplantation seems to be worse (HR: 1.39, p = 0.05) but only in the (incorrect but commonly applied) model without time varying covariates. The long term (time depending) hazard ratio is shown to be virtually 1 and overall survival is virtually identical in both groups. Nonetheless no conclusion can be reached from a clinical point of view without assumptions which are by their very nature untestable unless all patients would be followed from diagnosis.     

Biosorption of Heavy Metals (Cd2+, Cu2+, Co2+, and Mn2+) by Thermophilic Bacteria,Geobacillus thermantarcticus and Anoxybacillus amylolyticus: Equilibrium and Kinetic Studies

ABSTRACT

Two strains of thermophilic bacteria, Geobacillus thermantarcticus and Anoxybacillus amylolyticus, were employed to investigate the biosorption of heavy metals including Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ ions. The effects of different biosorption parameters such as pH (2.0–10.0), initial metal concentrations (10.0–300.0 mg L^?1), amount of biomass (0.25–10 g L^?1), temperature (30–80°C), and contact time (15–120 min) were investigated. Concentrations of metal ions were determined by using an inductively coupled plasma optical emission spectrometry (ICP-OES). Optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption by Geobacillus thermantarcticus were found to be 4.0, 4.0, 5.0, and 6.0, respectively. For Anoxybacillus amylolyticus, the optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption were found to be 5.0, 4.0, 5.0, and 6.0, respectively. The Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ removals at 50 mg L^?1 in 60 min by 50 mg dried cells of Geobacillus thermantarcticus were 85.4%, 46.3%, 43.6%, and 65.1%, respectively, whereas 74.1%, 39.8%, 35.1%, and 36.6%, respectively, for Anoxybacillus amylolyticus. The optimum temperatures for heavy metal biosorption were near the optimum growth temperatures for both strains. Scatchard plot analysis was employed to obtain more compact information about the interaction between metal ions and biosorbents. The plot results were further studied to determine if they fit Langmuir and Freundlich models.     

Molasses as fermentation substrate for levan production by <Emphasis Type="Italic">Halomonas</Emphasis> sp.

Levan is a homopolymer of fructose with many outstanding properties like high solubility in oil and water, strong adhesiveness, good biocompatibility, and film-forming ability. However, its industrial use has long been hampered by costly production processes which rely on mesophilic bacteria and plants. Recently, Halomonas sp. AAD6 halophilic bacteria were found to be the only extremophilic species producing levan at high titers in semi-chemical medium containing sucrose, and in this study, pretreated sugar beet molasses and starch molasses were both found to be feasible substitutes for sucrose. Five different pretreatment methods and their combinations were applied to both molasses types. Biomass and levan concentrations reached by the Halomonas sp. AAD6 cells cultivated on 30 g/L of pretreated beet molasses were 6.09 g dry cells/L and 12.4 g/L, respectively. When compared with literature, Halomonas sp. was found to stand out with its exceptionally high levan production yields on available fructose. Molecular characterization and monosaccharide composition studies confirmed levan-type fructan structure of the biopolymers. Rheological properties under different conditions pointed to the typical characteristics of low viscosity and pseudoplastic behaviors of the levan polymers. Moreover, levan polymer produced from molasses showed high biocompatibility and affinity with both cancerous and non-cancerous cell lines.     

Experimental evidence for adaptive personalities in a wild passerine bird

Individuals of the same species differ consistently in risky actions. Such ‘animal personality’ variation is intriguing because behavioural flexibility is often assumed to be the norm. Recent theory predicts that between-individual differences in propensity to take risks should evolve if individuals differ in future fitness expectations: individuals with high long-term fitness expectations (i.e. that have much to lose) should behave consistently more cautious than individuals with lower expectations. Consequently, any manipulation of future fitness expectations should result in within-individual changes in risky behaviour in the direction predicted by this adaptive theory. We tested this prediction and confirmed experimentally that individuals indeed adjust their ‘exploration behaviour’, a proxy for risk-taking behaviour, to their future fitness expectations. We show for wild great tits (Parus major) that individuals with experimentally decreased survival probability become faster explorers (i.e. increase risk-taking behaviour) compared to individuals with increased survival probability. We also show, using quantitative genetics approaches, that non-genetic effects (i.e. permanent environment effects) underpin adaptive personality variation in this species. This study thereby confirms a key prediction of adaptive personality theory based on life-history trade-offs, and implies that selection may indeed favour the evolution of personalities in situations where individuals differ in future fitness expectations.