Mobilization of R387 Inc K conjugative plasmid by the conjugative plasmid R64 Inc I

Plasmid aggregate (R387, R64) was constructed in E. coli K12 strain. Plasmid R387 Inc K was stimulated to conjugational transfer by plasmid R64 Inc I. This stimulation was caused neither by recombination between both plasmids nor by trans-complementation of R387 conjugational systems by gene(s) product(s) of R64 plasmid. The observed phenomenon resembled rather mobilization of nonconjugative plasmids by conjugative ones. As in mobilization, the observed increase in R387 transfer frequency could take place only when both interacting plasmids were present in donor cells. Moreover, the entry exclusion system functioning in recipient cells, toward stimulating R64 plasmid affected strongly the conjugational transfer of stimulated R387 plasmid. Analogous phenomenon was observed during mobilization of nonconjugative plasmids by conjugative ones.     

Identification of actin from hepatoma Morris 5123 cells

The hepatoma Morris 5123 tumor growth is accompanied by changes in actin content and polymerization (Malicka-B?aszkiewicz et al. (1995) Mat. Med. Pol., 27, 115-118; Nowak et al. (1995) J. Exp. Cancer Res. 14, 37-40). Presently actin isoforms from cytosol and cytoskeleton fractions were separated by SDS/PAGE and identified with antibodies directed against different actin isoforms. Actin isolated from the cytosol by affinity chromatography on DNase I bound to agarose shows the presence of only one protein spot on 2D gel electrophoresis corresponding to the mobility of the rabbit a skeletal muscle actin (Mr 43,000) and isoelectric point equal to 5.3. It interacts only with monoclonal anti beta actin isoform antibodies, posing the question of differential affinity of actin isoforms to DNase I.     

The optimality of the standard genetic code assessed by an eight-objective evolutionary algorithm

Background

The standard genetic code (SGC) is a unique set of rules which assign amino acids to codons. Similar amino acids tend to have similar codons indicating that the code evolved to minimize the costs of amino acid replacements in proteins, caused by mutations or translational errors. However, if such optimization in fact occurred, many different properties of amino acids must have been taken into account during the code evolution. Therefore, this problem can be reformulated as a multi-objective optimization task, in which the selection constraints are represented by measures based on various amino acid properties.

Results

To study the optimality of the SGC we applied a multi-objective evolutionary algorithm and we used the representatives of eight clusters, which grouped over 500 indices describing various physicochemical properties of amino acids. Thanks to that we avoided an arbitrary choice of amino acid features as optimization criteria. As a consequence, we were able to conduct a more general study on the properties of the SGC than the ones presented so far in other papers on this topic. We considered two models of the genetic code, one preserving the characteristic codon blocks structure of the SGC and the other without this restriction. The results revealed that the SGC could be significantly improved in terms of error minimization, hereby it is not fully optimized. Its structure differs significantly from the structure of the codes optimized to minimize the costs of amino acid replacements. On the other hand, using newly defined quality measures that placed the SGC in the global space of theoretical genetic codes, we showed that the SGC is definitely closer to the codes that minimize the costs of amino acids replacements than those maximizing them.

Conclusions

The standard genetic code represents most likely only partially optimized systems, which emerged under the influence of many different factors. Our findings can be useful to researchers involved in modifying the genetic code of the living organisms and designing artificial ones.

     

Polyploid speciation across a suture zone: phylogeography and species delimitation in S French <Emphasis Type="Italic">Leucanthemum</Emphasis> Mill. representatives (Compositae–Anthemideae)

Chromosome counts suggest that the three varieties of the SE French and NW Italian Leucanthemum vulgare subsp. glaucophyllum (var. glaucophyllum: decaploid; var. esterellense: octoploid; var. subglaucum: hexaploid) deserve acknowledgement as independent species. Here we use AFLP fingerprinting and sequence information from two chloroplast regions (psbA-trnH, rpl16) to gain insight into the evolutionary relationships among those species, along with those with the co-occurring and ecologically similar L. pallens (hexaploid) and the closely related L. ircutianum subsp. leucolepis (tetraploid). Both genetic marker systems reveal a geographical differentiation pattern in L. pallens with the Rhône valley forming a suture zone between the western (SW France, Spain) and eastern (SE France, NW Italy) populations, arguing for the existence of two lineages in the species that may have survived the Last Glacial Maximum (LGM) in refugia on the Iberian and Apennine Peninsulas. Transgressions of this suture zone are observable in the case of the hexaploid L. subglaucum from the Massif Central, which shows genetic relationships to the more eastern decaploid L. glaucophyllum from the Alps Maritimes, and the octoploid L. esterellense from the Esterel Massif (Côte d´Azur), for which relationships to the more western populations of the hexaploids L. pallens and L. subglaucum are observable. The genetic and cytological survey of a mixed stand of L. pallens and L. glaucophyllum on Monte Bignone (Liguria, NW Italy) reveals patterns of recent hybridisation of these two species with intermediate octoploid and nonaploid cytotypes that are, however, genetically distinct from L. esterellense.     

Chlorophyll fluorescence as a tool for nutrient status identification in rapeseed plants

In natural conditions, plants growth and development depends on environmental conditions, including the availability of micro- and macroelements in the soil. Nutrient status should thus be examined not by establishing the effects of single nutrient deficiencies on the physiological state of the plant but by combinations of them. Differences in the nutrient content significantly affect the photochemical process of photosynthesis therefore playing a crucial role in plants growth and development. In this work, an attempt was made to find a connection between element content in (i) different soils, (ii) plant leaves, grown on these soils and (iii) changes in selected chlorophyll a fluorescence parameters, in order to find a method for early detection of plant stress resulting from the combination of nutrient status in natural conditions. To achieve this goal, a mathematical procedure was used which combines principal component analysis (a tool for the reduction of data complexity), hierarchical k-means (a classification method) and a machine-learning method—super-organising maps. Differences in the mineral content of soil and plant leaves resulted in functional changes in the photosynthetic machinery that can be measured by chlorophyll a fluorescent signals. Five groups of patterns in the chlorophyll fluorescent parameters were established: the ‘no deficiency’, Fe-specific deficiency, slight, moderate and strong deficiency. Unfavourable development in groups with nutrient deficiency of any kind was reflected by a strong increase in F _o and ΔV/Δt ₀ and decline in φ _Po, φ _Eo δ _Ro and φ _Ro. The strong deficiency group showed the suboptimal development of the photosynthetic machinery, which affects both PSII and PSI. The nutrient-deficient groups also differed in antenna complex organisation. Thus, our work suggests that the chlorophyll fluorescent method combined with machine-learning methods can be highly informative and in some cases, it can replace much more expensive and time-consuming procedures such as chemometric analyses.     

Recent advances in biological production of erythritol

Erythritol is a natural sweetener commonly used in the food and pharmaceutical industries. Produced by microorganisms as an osmoprotectant, it is an ideal sucrose substitute for diabetics or overweight persons due to its almost zero calorie content. Currently, erythritol is produced on an industrial scale through the fermentation of sugars by some yeasts, such as Moniliella sp. However, the popularity of erythritol as a sweetener is still small because of its high retail price. This creates an opportunity for further process improvement. Recent years have brought the rapid development of erythritol biosynthesis methods from the low-cost substrates, and a better understanding of the metabolic pathways leading to erythritol synthesis. The yeast Yarrowia lipolytica emerges as an organism effectively producing erythritol from pure or crude glycerol. Moreover, novel erythritol producing organisms and substrates may be taken into considerations due to metabolic engineering. This review focuses on the modification of erythritol production to use low-cost substrates and metabolic engineering of the microorganisms in order to improve yield and productivity.     

Combination of resveratrol and 5‐azacytydine improves osteogenesis of metabolic syndrome mesenchymal stem cells

Endocrine disorders have become more and more frequently diagnosed in humans and animals. In horses, equine metabolic syndrome (EMS) is characterized by insulin resistance, hyperleptinemia, hyperinsulinemia, inflammation and usually by pathological obesity. Due to an increased inflammatory response in the adipose tissue, cytophysiological properties of adipose derived stem cells (ASC) have been impaired, which strongly limits their therapeutic potential. Excessive accumulation of reactive oxygen species, mitochondria deterioration and accelerated ageing of those cells affect their multipotency and restrict the effectiveness of the differentiation process. In the present study, we have treated ASC isolated from EMS individuals with a combination of 5‐azacytydine (AZA) and resveratrol (RES) in order to reverse their aged phenotype and enhance osteogenic differentiation. Using SEM and confocal microscope, cell morphology, matrix mineralization and mitochondrial dynamics were assessed. Furthermore, we investigated the expression of osteogenic‐related genes with RT‐PCR. We also investigated the role of autophagy during differentiation and silenced PARKIN expression with siRNA. Obtained results indicated that AZA/RES significantly enhanced early osteogenesis of ASC derived from EMS animals. Increased matrix mineralization, RUNX‐2, collagen type I and osteopontin levels were noted. Furthermore, we proved that AZA/RES exerts its beneficial effects by modulating autophagy and mitochondrial dynamics through PARKIN and RUNX‐2 activity.