Paradigm shift in eukaryotic biocrystallization

Despite the widespread occurrence of crystalline inclusions in unicellular eukaryotes, scant attention has been paid to their composition, functions, and evolutionary origins, assuming just their inorganic contents. The advent of Raman microscopy, still scarcely used for biological samples, allowed chemical characterization of cellular inclusions in vivo. Using this method, herein we provide a substantial revision of the cellular crystalline inclusions across the broad diversity of eukaryotes examining all major supergroups. Surprisingly, here we show that 80 % of these crystalline inclusions contain purines, mostly anhydrous guanine (62 %), guanine monohydrate (2 %), uric acid (12 %) and xanthine (4 %). Hence, our findings indicate that purine biocrystallization is a very general and an ancestral eukaryotic process operating by an as-yet-unknown mechanism. Purine crystalline inclusions are high-capacity and rapid-turnover reserves of nitrogen of a great metabolic importance, as well as optically active elements, e.g., present in the light sensing eyespots of flagellates, possessing even more hypothetical functions. Thus, we anticipate our work to be a starting point for more in-depth studies of this phenomenon on the detailed level spanning from cell biology to global ecology, with further potential applications in biotechnologies, bio-optics or in human medicine.

A Key for the Microhistological Determination of Plant Fragments Consumed by Carpathian Forest Cervids

We present a microhistological key for identification of plant fragments consumed and partially digested by free-roaming, forest cervids based on collection of 92 plant species representing forage availability of the Western Carpathian forests. The key represents a determination tool to facilitate microhistological analyses of faecal and ruminal material. We summarized, integrated, and developed current knowledge on microstructures of plants consumed by Cervidae using specific diagnostic features of plant fragments including type, shape, orientation, and arrangement of cells and stomata, type of venation, presence, and type of trichomes and crystalline inclusions. Since most plant species of the same taxa show common patterns in morphology of the different epidermal traits, we categorized collected material into seven functional botanical groups, i.e., grasses and sedges, herbs and leaves of broadleaved trees, needles, ferns and mosses, seeds and fruits, and genera Rubus, Rosa, Vaccinium. The key is consistent with classifications used in the majority of studies on diet of wild cervids and is supported with photographs of the main diagnostics features. The key has the potential to decrease amount of time needed for processing of the reference material, and to improve consistency between users studying feeding behaviour of forest cervids in central Europe.

Research of Regularities of Aerosol Synthesis of Iron Oxide Particles

The influence of the concentration of the initial solution on the size and composition of the particles obtained by the method of ultrasonic spray pyrolysis (USP) was investigated. An aqueous solution of Fe (NО3)3·9Н2О, the concentration of which varied in the range of 0,0025–0,03 mol/l, was used as the starting material. As a result of the process, iron oxide particles were obtained, the average size of which varied from 123 to 292 nm. Based on FTIR and XRD, powders consist of several phases and have crystalline inclusions α-Fe2O3, β-Fe2O3, and γ-Fe2O3.