Determination of trace elements in standard reference materials by the ko-standardization method

Biological Trace Element Research - The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard...     

Structural and functional homology between the 29 kD rat liver nucleoprotein and the high mobility group 1 protein

A 29 kD soluble rat liver nucleoprotein (p29) has increased binding affinity for the hormone responsive element (RE) of the rat haptoglobin (Hp) gene during the acute-phase reaction. In this work the possibility of its structural and functional homology to the high mobility group 1 (HMG1) nonhistone protein constituent of chromatin was examined. The results of two-dimensional gel electrophoresis, Southwestern and Western immunoblot analyses, showed that p29 and HMG1 are homologous protein species. On the basis of in vitro and in vivo phosphorylation/dephosphorylation experiments, we discuss the modulatory role of phosphate groups in view of the structure and function of p29.     

Trophic role of rotifers in the plankton of lake Kozjak (Plitvice Lakes)

The trophic role of rotifers in the zooplankton community of dimictic, oligotrophic lake Kozjak, the largest lake of the Plitvice Lakes, NW Dinarid Mountains, is analyzed. Their spatial and temporal biomass distribution in relation to that of protozoans, cladocerans and copepods shows that they form a significant part of the non-predatory zooplankton of this karstic standing water.     

Membrane fluidity in glutamic acid-producing bacteria Brevibacterium sp. ATCC 13869

The bacterial secretion of glutamate was studied through plasma membrane fluidity, measured by anisotropy using the fluorophore TMA-DPH incorporated in the lipid part of the cell membrane. Cells of Brevibacterium sp. ATCC 13869 (wild type) were switched from the biotin-limited, producing state to the biotin-supplemented, non-producing state, and back. The following conclusions could be drawn: 1. It was not possible to detect any change in anisotropy by switching the cells from biotin-limited biotin-supplemented, as well as from biotin-supplemented, to biotin-limited, media. 2. The anisotropy value in the glutamic acid fermentation remains constant during the lag, exponential, growth, production and stationary phases. 3. The treatment of cells with a neutral synthetic polyester of ethylene-and propyleneoxide with soya oil-fatty acids increased the anisotropy values, indicating incorporation of the surfactant. 4. Glutamate secretion is not coupled with membrane fluidity, so a leak providing a general fluidization of the membrane could not be detected.     

Significant increase in natural disturbance impacts on European forests since 1950

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m³ of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m³/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes.     

Quality Assessment of Bee Pollen-Honey Mixtures Using Thin-Layer Chromatography in Combination with Chemometrics

The aim of this study is to develop a rapid, effect-directed screening method for quality assessment of bee pollen-honey mixtures. The comparative antioxidant potential and phenolic content of honey, bee pollen, and the bee pollen-honey mixtures, was performed using spectrophotometry. The total phenolic content and antioxidative activity of bee pollen-honey mixtures with 20 % bee pollen share were in the range 3.03–3.11 mg GAE/g, and 6.02–6.96 mmol TE/kg, respectively, while mixtures with 30 % bee pollen share contained 3.92–4.18 mg GAE/g, and 9.69–10.11 mmol TE/kg. Chromatographic fingerprint of bee pollen-honey mixtures was performed by high-performance thin-layer chromatography with conditions developed by authors and reported for the first time. Fingerprint analysis hyphenated with chemometrics enabled authenticity assessments of honey in mixtures. Results indicate that bee pollen-honey mixtures represent a food with highly, both, nutritious characteristics and health-promoting effect.     

Temperature and dissolved oxygen concentration as parameters of Azotobacter chroococcum cultivation for use in biofertilizers

Summary Azotobacter chroococcum was grown in continuous culture at two temperatures (30 °C and 20 °C) and different dissolved oxygen tensions (DOT) (30 % to 40 % and 70 % to 80 % of air saturation), respectively. At the temperature of 30 °C and low DOT a relatively high volumetric productivity and efficiency of nitrogen fixation were obtained. After lowering the temperature to 20 °C, an intensive formation of cysts was observed associated with a drastic decrease of the bacterial growth. Bacteria in the form of cysts kept their physiological activity for a long period of time depending on temperature and preparation.     

Regeneration of Picea omorika plants via organogenesis

Picea omorika plants were regenerated from embryo and seedling shoot tip cultures. Adventitious and axillary shoots were produced on 1/2 MS medium containing benzyladenine and kinetin. Benzyladenine was more effective in bud induction, whereas kinetin hastened shoot development. Excised shoots were elongated on 1/3 MS medium without growth regulators, multiplied with kinetin and rooted with or without indole-3-butyric acid.Abbreviations BA N⁶-benzyladenine - 2IP N ⁶-(²-isopenteny) adenine - NAA -naphthaleneacetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid