Natural variation identifies SNI1, the SMC5/6 component, as a modifier of meiotic crossover in Arabidopsis.

The frequency and distribution of meiotic crossovers are tightly controlled; however, variation in this process can be observed both within and between species. Using crosses of two natural Arabidopsis thaliana accessions, Col and Ler, we mapped a crossover modifier locus to semidominant polymorphisms in SUPPRESSOR OF NPR1-1 INDUCIBLE 1 (SNI1), which encodes a component of the SMC5/6 complex. The sni1 mutant exhibits a modified pattern of recombination across the genome with crossovers elevated in chromosome distal regions but reduced in pericentromeres. Mutations in SNI1 result in reduced crossover interference and can partially restore the fertility of a Class I crossover pathway mutant, which suggests that the protein affects noninterfering crossover repair. Therefore, we tested genetic interactions between SNI1 and both RECQ4 and FANCM DNA helicases, which showed that additional Class II crossovers observed in the sni1 mutant are FANCM independent. Furthermore, genetic analysis of other SMC5/6 mutants confirms the observations of crossover redistribution made for SNI1 The study reveals the importance of the SMC5/6 complex in ensuring the proper progress of meiotic recombination in plants

Animals' ethics in the light of the idea of sustainable development

W artykule podejmuje się próbę nakreślenia historyczno-kulturowych źródeł etyki zwierząt. W związku z tym wyróżnia się w porządku chronologicznych status predmitologiczny, mitologiczny, religijny oraz filozoficzny zwierząt. Tylko w przypadku pierwszego mamy do czynienia wyłącznie ze statusem praktycznym, pozostałe mają charakter statusów teoretycznych określających "wyższe racje" traktowania zwierząt w danej kulturze. Obecnie jesteśmy w sytuacji, w której nasz etyczny stosunek do zwierząt podyktowany jest przez ich praktyczne znaczenie. Idea zrównoważonego rozwoju może stać się poważnym programem naprawczym, jeśli tylko będzie w stanie wygenerować w obrębie swej integralnej propozycji nowy teoretyczny (filozoficzny) status zwierząt, oparty na współczesnych badaniach biologicznych (etologicznych, socjobiologicznych, genetycznych).The article is an attempt to present historical and cultural sources of animals' ethics. In chronological order the premythological, mythological, religious and philosophical statuses of animals are presented. Only the first of which is wholly the practical status. The rest of them are theoretical, each presents 'superior cause' for treating animals in specific culture. Presently we are in situation in which our ethical relation towards animals is determined by their practical importance. The idea of sustainable development may become significant remedy programme for such issue, if only it would be able to generate within its integral proposition a new theoretical (philosophical) animals' status based on modern biological studies (ethological, sociobiological, genetical)

Horizontal and vertical distribution of lignin in surface sediments of the Gdańsk Basin

The aim of this study was to identify and quantify lignin transported from the River Vistula to the accumulation area in the Gdańsk Basin. Sediment samples collected along the Vistula mouth –Gdańsk Deep transect were analysed for lignin. Lignin was characterised by oxidative degradation, cupric oxide being chosen as the most suitable oxidising agent. The polar functional groups of the oxidation products were silylated and the derivatives analysed by capillary gas chromatography on fused capillary silica columns with flame ionisation detection. Lignin-derived oxidation products were quantified in the range from 3 to 20 μg g−1 dry wt. for phenolic acids and from 6 to 12 μg g−1 dry wt. for phenolic aldehydes. Differences in oxidation products contents are assigned to different lignin sources in the marine environment. The horizontal and vertical gradients of these compounds in the sediments of the Gdańsk Basin are documented. The results are discussed in terms of the origin and fate of organic matter in the Gdańsk Basin. The measured differences in quality and quantity of the identified oxidation products provide insight into diagenetic processes in the surface marine sediments

Wpływ zwięzłości gleby na jej parametry wytrzymałościowe

Przedstawiono wyniki pomiarów naprężeń ścinających przeprowadzonych w warunkach polowych, metodą bezpośredniego ścinania dla dwóch gleb o zróżnicowanym składzie granulometrycznym, przy różnych poziomach naprężeń normalnych i zwięzłości gleby. Naprężenia normalne, zwięzłość gleby i jej skład granulometryczny wpływają na wartości naprężeń ścinających. Wzrost zwięzłości gleby powoduje wzrost spójności, nie wpływa natomiast na wartość kąta tarcia wewnętrznego.There are presented the results of shearing stress measurements carried out in field conditions with the method of direct shearing. Tests were performed on two kinds of soil of differentiated granulometric composition with different level of normal stress and soil compaction. Normal stress, soil compaction and its granulometric composition were found to have influenced the values of shearing stresses. On the grounds of derived empirical formulae the dependence of shearing stresses on normal ones and soil compaction appeared to be linear. Increase in soil compaction brought about increased cohesion, but had no influence on the internal friction angle