Insight into the Assembly Properties and Functional Organisation of the Magnetotactic Bacterial Actin-like Homolog, MamK

Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth’s magnetic field. MamK, an actin-like homolog of MreB has been identified as a central component in this organisation. Gene deletion, fluorescence microscopy and in vitro studies have yielded mechanistic differences in the filament assembly of MamK with other bacterial cytoskeletal proteins within the cell. With little or no information on the structural and behavioural characteristics of MamK outside the cell, the mamK gene from Magnetospirillium gryphiswaldense was cloned and expressed to better understand the differences in the cytoskeletal properties with its bacterial homologues MreB and acitin. Despite the low sequence identity shared between MamK and MreB (22%) and actin (18%), the behaviour of MamK monitored by light scattering broadly mirrored that of its bacterial cousin MreB primarily in terms of its pH, salt, divalent metal-ion and temperature dependency. The broad size variability of MamK filaments revealed by light scattering studies was supported by transmission electron microscopy (TEM) imaging. Filament morphology however, indicated that MamK conformed to linearly orientated filaments that appeared to be distinctly dissimilar compared to MreB suggesting functional differences between these homologues. The presence of a nucleotide binding domain common to actin-like proteins was demonstrated by its ability to function both as an ATPase and GTPase. Circular dichroism and structural homology modelling showed that MamK adopts a protein fold that is consistent with the ‘classical’ actin family architecture but with notable structural differences within the smaller domains, the active site region and the overall surface electrostatic potential

Productivity and wholesomeness of faba bean in relation to quality of the sown material and method and period fungicides application

Field experiment was carried out in 1992-1994 in the Agricultural Experimental Station Balcyny to study the effect of the quality seeds faba bean and the effectiveness of different fungicides applications on the growth, wholesomeness and yield of faba bean, Dino cultivar. Wholesomeness of the sown material and applied fungicides did not significantly affect on yield bean. Fungicides Sportak 45 EC and combined treatment Sportak 45 EC + Ronilan WP limited the infestation of plants only in early phases of growth

Wpływ nawożenia azotem i inokulacji Rhizobium na plon i jakość Trigonella foenum-graecum L.

Fenugreek is one of the oldest known medicinal plants that have been used in traditional medicine in many parts of the world. The aim of this study was to determine the effects of nitrogen fertilization and Rhizobium meliloti inoculation on the yield, yield components and seed quality of fenugreek. The experiment was performed during two growing seasons. Chlorophyll content was determined with the use of the SPAD-502 chlorophyll meter. After harvest, biometric measurements were performed and the chemical composition of vegetative organs and seeds was determined in fenugreek plants. At 43 DAS, the chlorophyll content of control plant leaves was determined as 46 SPAD, and it decreased with plant growth. In treatments fertilized with nitrogen, the chlorophyll content of leaves increased from 48.5 (N0.5) - 56.1 (N1) SPAD (43 DAS) to 58.2 (N0.5) - 60.6 (N1) SPAD (58 DAS).Seed inoculation with Rhizobium meliloti was more highly correlated with seed quality than plant habitus and yield components. Inoculation decreased (by 11.5%) the crude fat content of fenugreek seeds, and increased phosphorus, calcium and sodium concentrations. Nitrogen fertilization significantly influenced morphological parameters and yield components, and it contributed to a significant increase in the total protein content of seeds.Kozieradka pospolita jest jedną z najstarszych roślin leczniczych, była wykorzystywana w tradycyjnej medycynie w wielu częściach świata. Celem badań było określenie wpływu nawożenia azotem i inokulacji Rhizobium meliloti na plonowanie i zawartość składników w nasionach kozieradki. Eksperyment przeprowadzono w dwóch sezonach wegetacyjnych. Zawartość chlorofilu określono za pomocą chlorofilomierza SPAD-502. Po zbiorze wykonano pomiary biometryczne i oznaczono skład chemiczny nasion i wegetatywnych części roślin. W 43. dniu po siewie (DAS) zawartość chlorofilu w liściach roślin kontrolnych wynosiła 46 SPAD i zmniejszała się wraz ze wzrostem roślin. Na obiektach nawożonych azotem zawartość chlorofilu w liściach zwiększała się z 48,5 (N0.5) - 56,1 (N1) SPAD (43 DAS) do 58,2(N0.5) - 60,6(N1) SPAD (58 DAS ). Inokulacja materiału siewnego Rhizobium meliloti w większym stopniu wpływała na jakość nasion niż na pokrój roślin i komponenty plonu, zmniejszyła (do 11,5%) zawartość tłuszczu surowego i zwiększyła zawartość fosforu, wapnia i sodu w nasionach kozieradki. Nawożenie azotem istotnie różnicowało parametry morfologiczne roślin i komponenty plonu, co skutkowało istotnym wzrostem zawartości białka w nasionach

Mechanical properties of a single red clover seed

W pracy przedstawiono właściwości mechaniczne nasion diploidalnych i tetraploidalnych odmian koniczyny czerwonej uprawianych w różnych gęstościach siewu i w trzech latach badań. W tym celu nasiona poddano testowi jednoosiowego ściskania do założonego odkształcenia, za pomocą uniwersalnej maszyny testującej INSTRON. określono siłę niszczącą nasiono, odpowiadającą granicy wytrzymałości biologicznej (Fmax) i energię (pracę) powodującą zniszczenie struktury nasiona (Emax) oraz obliczono parametr odkształcenia nasion będący ilorazem siły (DF) i odkształcenia względnego (DD). Przeprowadzona analiza statystyczna wykazała różnice pomiędzy badanymi cechami mechanicznymi nasion w zależności od odmiany, gęstości siewu i kolejnych lat badań. Wszystkie parametry mechaniczne nasion zależały od warunków klimatycznych w latach badań; uprawa w warunkach niesprzyjających (nadmiar opadów) powodowała wzrost wartości tych parametrów. Wytrzymałość nasion na ściskanie zależała istotnie od ploidalności odmian koniczyny czerwonej oraz od warunków uprawy. Stwierdzono, że Fmax, Emax, oraz DF/DD określają w podobnym stopniu właściwości mechaniczne pojedynczych nasion koniczyny czerwonej.The paper presents the results of determination of mechanical properties of seeds of di- and tetraploid red clover cultivars which were cultivated at different sowing density and in varied climatic conditions of the three years 2002-2004. The batches of seeds collected in each year were subjected to the test of uniaxial compression up to the anticipated seed deformation (75%) with the use of the universal test apparatus INSTRON. The measurements included the force of seed destruction related to the limit of biological strength, the energy (work) causing the destruction of seed structure, and a parameter of deformation which is the ratio between the increase of the force (DF) and relative deformation (DD). Statistical analysis showed significant contrasts between diand tetraploid cultivars, sowing densities and years of study. All the measured characteristics were determined by the climatic conditions in the vegetation seasons. The cultivation of red clover under conditions of excessive precipitation caused an increase in all of the measured mechanical properties. The strength parameters of red clover seeds depended on the ploidity of cultivars which, depending on the climatic conditions, reacted variously. Besides, sowing density may also have had a significant impact on the seed mechanical parameters. It was observed that Fmax, Emax, as well DF/DD gave similar information on red clover seed strength