Background processes at the population level during succession in grasslands on sand

Two population characteristics, reproductive allocation (RA) and the intensity of photosynthesis, were investigated in the successional stages of the sandy grassland communities of the Great Hungarian Plain. Most of the species studied changed their allocational response as succession advanced. Compound path schemes, as casual models, were constructed and analysed for describing intra-individual effects (influence of assimilating organs and root mass of the plant sampled) as well as the phytosociological effects on RA. In pioneer stages, the high values of path coefficients show that the effect of assimilating organs is responsible for the variability of RA. It is also shown that annuals and perennials exhibit different behaviour as to the regulation of RA. It seems that-in terms of path analysis-the reproduction of annuals is influenced by internal factors only. In case of perennials, an external (namely phytosociological) regulation was also observed. It is suggested that successional stages play a role in regulating the photosynthetic intensity of both the dominant species and the whole plant assemblage.Abbreviations RA = Reproductive Allocation     

Do MCF7 cells cope with metformin treatment under energetic stress in low glucose conditions?

There is a growing body of evidence about metformin being effective in cancer therapy. Despite controversies about the ways of its effectiveness, several ongoing clinical trials are evaluating the drug when used as an adjuvant or a neo-adjuvant agent. We aimed to investigate metformin’s effects on proliferation, metastasis, and hormone receptor expressions in breast cancer cell line MCF-7 incubated in two different glucose conditions. MCF-7 cells were incubated in high or low glucose media and treated with various doses of metformin. The cell viability was studied using MTT test. The Ki-67, estrogen and progesterone receptor expression were evaluated by ICC and galectin-3 expression was evaluated by ELISA or spectrophotometrically. The cell viability following consecutive metformin doses in either glucose condition for 24 and 48 h represented a significant decrease when compared to control. The proliferation detected in low glucose medium following metformin at doses < 20 mM was found significantly decreased when compared to high glucose medium at 48 h. In terms of galectin-3 levels, the increase in high glucose medium treated with metformin and the decrease in low glucose medium were found statistically significant when compared to control. Progesterone receptor staining demonstrated a significant increase in low glucose medium. Our findings represent better outcomes for cancer lines incubated in low glucose medium treated with metformin in terms of viability, receptor expression and metastatic activity, and highlight the potential benefit of metformin especially in restraining the cancer cell’s ability to cope energetic stress in low glucose conditions.     

Comparison of ELISA with shell vial cell culture method for the detection of human rotavirus in fecal specimens

The aim of the study was to compare an enzyme immunoassay method with shell vial cell culture method for detection of rotavirus in fecal specimens. In addition, the correlation between laboratory results and clinical scores of patients with gastroenteritis was evaluated. A total of 219 fecal specimens from children (ages 3 weeks to 5 years) with acute gastroenteritis submitted to pediatric emergency room were evaluated by both ELISA and shell vial cell culture. A Vesikari score was used for assessing the severity of the illness. Among 219 stool samples tested, 107 (48.9%) were determined to be positive. Two specimens were positive by shell vial cell culture method while they were ELISA negative. According to these results the calculated sensitivity, specificity, PPV, and NPV of ELISA were 98.1%, 100%, 100%, and 98.2%, respectively. The mean severity score for the 107 episodes of rotavirus diarrhoea was 11.0 +/- 3.6 compared to 4.5 +/- 1.9 for the 112 episodes of non-rotavirus diarrhea in the same population. Our study indicates that ELISA, which is easier to perform, faster and cheaper than cell culture methods may be suitable for routine diagnosis of rotavirus infections. The severity of rotavirus positive gastroenteritis was significantly higher than that of rotavirus negative patients.     

A comparative study of the metal ion uptake and antioxidant enzyme activities of Fusarium equiseti and Fusarium acuminatum as a function of external magnesium concentration

The increase of Mg2+, from 1.3 to 3 microM, in growth medium of F. equiseti and F. acuminatum increased intracellular magnesium levels from 0.83 and 0.81 microM to 1.75 and 1.42 microM on the 12th day, respectively. Intracellular magnesium levels also elevated depending upon the number of incubation days. The maximum manganese levels of F. equiseti and F. acuminatum obtained in 1.6 microM Mg2+ culture medium were 0.67 and 1.23 microM, while maximum iron levels were determined to be 1.3 microM Mg2+ as 0.51 and 0.29 microM, respectively. The maximum intracellular iron and manganese levels were decreased significantly with increasing Mg2+ concentration in the culture medium and were increased depending upon the incubation period. However, intracellular zinc levels of these strains didn't change with Mg2+ concentration and incubation period.The maximum superoxide dismutase (MnSOD) activities of F. equiseti and F. acuminatum, related to increased intracellular manganese levels up to 1.6 microM Mg2+ in growth medium, were determined to be 78 and 110 IU/mg, respectively. CAT activity variations showed agreement with SOD activity and reached a maximum at 320 and 225 IU/mg under the same conditions. The minimum LPO levels of the Fusarium strains with the maximum MnSOD and CAT activities were determined as 1.2 and 0.9 nmol MDA/g., wet weight. The higher LPO level of F. equiseti grown at the same condition, in spite of 1.42-fold higher CAT activity due to the 1.41-fold lower SOD activity, as well as a 2.0-fold higher iron level, indicated increases in the generation of reactive oxygen species via the Fenton reaction.     

Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A,Isolated from Hanford 300A Subsurface Sediments

A facultative iron-reducing [Fe(III)-reducing] Paenibacillus sp. strain was isolated from Hanford 300A subsurface sediment biofilms that was capable of reducing soluble Fe(III) complexes [Fe(III)-nitrilotriacetic acid and Fe(III)-citrate] but unable to reduce poorly crystalline ferrihydrite (Fh). However, Paenibacillus sp. 300A was capable of reducing Fh in the presence of low concentrations (2 μM) of either of the electron transfer mediators (ETMs) flavin mononucleotide (FMN) or anthraquinone-2,6-disulfonate (AQDS). Maximum initial Fh reduction rates were observed at catalytic concentrations (<10 μM) of either FMN or AQDS. Higher FMN concentrations inhibited Fh reduction, while increased AQDS concentrations did not. We also found that Paenibacillus sp. 300A could reduce Fh in the presence of natural ETMs from Hanford 300A subsurface sediments. In the absence of ETMs, Paenibacillus sp. 300A was capable of immobilizing U(VI) through both reduction and adsorption. The relative contributions of adsorption and microbial reduction to U(VI) removal from the aqueous phase were ∼7:3 in PIPES [piperazine-N,N′-bis(2-ethanesulfonic acid)] and ∼1:4 in bicarbonate buffer. Our study demonstrated that Paenibacillus sp. 300A catalyzes Fe(III) reduction and U(VI) immobilization and that these reactions benefit from externally added or naturally existing ETMs in 300A subsurface sediments.     

The variation of antioxidant defense system of Streptomyces sp. M4018 with respect to carbon sources

The effect of glycerol, glucose, and starch as carbon sources on the antioxidant defense system such as superoxide dismutase (SOD) and catalase (CAT) activities, pyruvate levels, and membrane lipid peroxidation (LPO) levels of Streptomyces sp. M4018, after isolation from the rhizosphere samples of Colutea arborescens and identification as a strain of S. hiroshimensis based on phenotypic and genotypic characteristics, were investigated. As an antioxidant defense enzyme, SOD activities increased up to 20 g/L of glycerol and 15 g/L of starch, while they showed negative correlation with glucose concentration. CAT activity variations of glycerol- and glucose-supplemented mediums showed significant positive correlations with the trend of SOD activities. However, CAT activity, in contrast to SOD, in Streptomyces sp. M4018 tended to decrease as the starch concentration increased. The production of pyruvate increased with respect to glycerol and starch up to 15 g/L, while it was positively correlated with glucose concentration. The highest pyruvate production was seen at 20 g/L glucose. Membrane LPO levels were negatively correlated with the activities of SOD and CAT enzymes, and the minimum LPO level was determined at 5 g/L of glucose, where SOD and CAT activities reached their maximum levels. Nevertheless, the higher SOD and CAT activities in a wider range of incubation period compared to the beginning by resulting in insignificant increases in membrane LPO levels showed the unusual antioxidant response capacities of the in Streptomyces sp. M4018 against the potentially deleterious effects of reactive oxygen species (ROS) for glycerol, glucose, and starch as carbon sources.