Mechanical stress-induced reorganization of the root stem cel niche of Arabidopsis seedlings cultured in vitro

doi wspólne dla całości materiałów konferencyjnychSesja posterowa - XIV Overall Polish in vitro Culture and Plant Biotechnology Conference Structural, physiological and molecular bases of plant differentiation September 14-17, 2015, Pozna

Easier done than said? An Empirical Analysis of Case Law on Platform Work in the EU

The paper provides a quantitative analysis of case law on platform work issued in the EU Member States by October 2022. It presents a year-to-year deconstruction of case law; examines the distribution of case law per country and sector; compares the reclassification rates across all sectors, and identifies the criteria most referred to when deciding about the employment status of platform workers. It calls for a refocusing of the debate on employment classification on the under-researched sectors of platform work and emphasises the need for effective, comprehensive regulatory solutions

Distribution of lipid transfer protein 1 (LTP1) epitopes associated with morphogenic events during somatic embryogenesis of Arabidopsis thaliana

Using immunocytochemical methods, at both the light and electron microscopic level, we have investigated the spatial and temporal distribution of lipid transfer protein 1 (LTP1) epitopes during the induction of somatic embryogenesis in explants of Arabidopsis thaliana. Immunofluorescence labelling demonstrated the presence of high levels of LTP1 epitopes within the proximal regions of the cotyledons (embryogenic regions) associated with particular morphogenetic events, including intense cell division activity, cotyledon swelling, cell loosening and callus formation. Precise analysis of the signal localization in protodermal and subprotodermal cells indicated that cells exhibiting features typical of embryogenic cells were strongly labelled, both in walls and the cytoplasm, while in the majority of meristematic-like cells no signal was observed. Staining with lipophilic dyes revealed a correlation between the distribution of LTP1 epitopes and lipid substances within the cell wall. Differences in label abundance and distribution between embryogenic and non-embryogenic regions of explants were studied in detail with the use of immunogold electron microscopy. The labelling was strongest in both the outer periclinal and anticlinal walls of the adaxial, protodermal cells of the proximal region of the cotyledon. The putative role(s) of lipid transfer proteins in the formation of lipid lamellae and in cell differentiation are discussed

Various scenarios of the cell pattern formation in Arabidopsis lateral root

During lateral root (LR) development a coordinate sequence of cell divisions, accompanied by a change of the organ form takes place. Both the order of anatomical events and morphological features may vary for individual primordia. At early stages of LR primordia development oblique division walls are inserted in cells that are symmetrically located on both sides of the axis of the developing LR primordium, and thereby allow for the protrusion of the LR. We hypothesize that both oblique cell wall insertion and continuous changes in primordium form could be a consequence of a local change in stress distribution in the region of the LR initiation

Spatio-temporal localization of selected pectic and arabinogalactan protein epitopes and the ultrastructural characteristics of explant cells that accompany the changes in the cell fate during somatic embryogenesis in Arabidopsis thaliana

During somatic embryogenesis (SE), explant cells undergo changes in the direction of their differentiation, which lead to diverse cell phenotypes. Although the genetic bases of the SE have been extensively studied in Arabidopsis thaliana, little is known about the chemical characteristics of the wall of the explant cells, which undergo changes in the direction of differentiation. Thus, we examined the occurrence of selected pectic and AGP epitopes in explant cells that display different phenotypes during SE. Explants examinations have been supplemented with an analysis of the ultrastructure. The deposition of selected pectic and AGP epitopes in somatic embryos was determined. Compared to an explant at the initial stage, a/embryogenic/totipotent and meristematic/pluripotent cells were characterized by a decrease in the presence of AGP epitopes, b/the presence of AGP epitopes in differentiated cells was similar, and c/an increase of analyzed epitopes was detected in the callus cells. Totipotent cells could be distinguished from pluripotent cells by: 1/the presence of the LM2 epitope in the latest one, 2/the appearance of the JIM16 epitope in totipotent cells, and 3/the more abundant presence of the JIM7 epitope in the totipotent cells. The LM5 epitope characterized the wall of the cells that were localized within the mass of embryogenic domain. The JIM8, JIM13 and JIM16 AGP epitopes appeared to be the most specific for the callus cells. The results indicate a relationship between the developmental state of the explant cells and the chemical composition of the cell walls

Endothelin as a local regulating factor in the bovine oviduct

Endothelin (EDN) is a possible regulating factor of oviductal motility, which is important for the transport of gametes and embryo. To clarify the factors that control the secretion of EDN in the bovine oviduct, the expression of EDNs, EDN-converting enzymes (ECEs) and EDN receptors (EDNRs) were investigated. All isoforms of EDN (EDN1-3), ECE (ECE1 and ECE2) and EDNR (EDNRA and EDNRB) were immunolocalised in the epithelial cells of the ampulla and the isthmus. EDNRs were also immunolocalised in smooth-muscle cells. The mRNA expression of EDN2 and ECE2 was higher in cultured ampullary oviductal epithelial cells than in isthmic cells. The expression of EDN1, EDN2 and ECE2 in the ampullary tissue was highest on the day of ovulation. Oestradiol-17β increased EDN2 and ECE1 expression, while progesterone increased only ECE1 expression in cultured ampullary epithelial cells. These results indicate that EDNs are produced by epithelial cells and their target site is smooth-muscle and epithelial cells, and suggest that ovarian steroids are regulators of endothelin synthesis in ampullary oviductal epithelial cells

The assessment of influence of different nitrogen compounds and time on germination of Lupinus angustifolius seeds and chemical composition of final products

The aim of the research was to determine changes in the chemical composition in lupin seeds during seed germination in a solution containing selected nitrogen compounds. Blue lupin seeds of the Neptun cultivar were germinated for 3 or 4 days in darkness, at 24°C in 1% solutions containing the following nitrogen compounds: urea, nitric acid, ammonium sulphate, methionine or yeast extract. The control consisted of seeds germinated in water. The presence of all nitrogen sources has resulted in a poorer growth of the sprouts as compared to seeds germinated in water. There was a significant increase in the true protein content as well as a significant decrease in the content of crude ash and alkaloids in the germinated seeds. The seeds germinated for 4 days had significantly higher total protein content and significantly lower content of nitrogen-free extract compounds and oligosaccharides as compared to the seeds germinated for 3 days. A significant influence of the nitrogen source on the concentration of some amino acids was found. Cystine was found to be absent in seeds germinated in the nitric acid solution, while there occurred a twofold increase in the cystine content and a fivefold increase in the methionine content in seeds germinated in the aqueous solution of methionine and an 50% increase in the cystine concentration was observed in seeds germinated in the yeast extract and ammonium sulphate solution. Methionine and cystine were the limiting amino acids in all the samples, accept of seeds germinated in the methionine solution were it was valine. Aqueous solutions of ammonium sulphate and yeast extract were found to have the most advantageous influence on the chemical composition of lupin germination products

Invisible workers : who is behind the artificial intelligence?

The article is dedicated to microworkers-highly precarious, often "invisible" workers whose labour is pivotal for the development of artificial intelligence (AI). It examines how crowdwork platforms such as Amazon Mechanical Turk, Appen and Clickworker organise the work of globally dispersed workers annotating data. It argues that, more often than not, this kind of work is performed in a highly structured, yet intransparent way, and is subject to substantial algorithmic control. This gives rise to the question of the employment classification of formally independent microworkers. The paper discusses this issue in light of the proposed Directive on the improved working conditions of platform workers

Topological traits of a cellular pattern versus growth rate anisotropy in radish roots

The topology of a cellular pattern, which means the spatial arrangement of cells, directly corresponds with cell packing, which is crucial for tissue and organ functioning. The topological features of cells that are typically analyzed are the number of their neighbors and the cell area. To date, the objects of most topological studies have been the growing cells of the surface tissues of plant and animal organs. Some of these researches also provide verification of Lewis’s Law concerning the linear correlation between the number of neighboring cells and the cell area. Our aim was to analyze the cellular topology and applicability of Lewis’s Lawto an anisotropically growing plant organ. The object of our study was the root apex of radish. Based on the tensor description of plant organ growth, we specified the level of anisotropy in specific zones (the root proper, the columella of the cap and the lateral parts of the cap) and in specific types of both external (epidermis) and internal tissues (stele and ground tissue) of the apex. The strongest anisotropy occurred in the root proper, while both zones of the cap showed an intermediate level of anisotropy of growth. Some differences in the topology of the cellular pattern in the zones were also detected; in the root proper, six-sided cells predominated, while in the root cap columella and in the lateral parts of the cap, most cells had five neighbors. The correlation coefficient rL between the number of neighboring cells and the cell area was high in the apex as a whole as well as in all of the zones except the root proper and in all of the tissue types except the ground tissue. In general, Lewis’s Law was fulfilled in the anisotropically growing radish root apex. However, the level of the applicability (rL value) of Lewis’s Lawwas negatively correlated with the level of the anisotropy of growth, which may suggest that in plant organs in the regions of anisotropic growth, the number of neighboring cells is less dependent on the cell size

Collection and management of collections in the academic library. From the experience of Main Library of the Warsaw University of Technology

In the paper management of Main Library of the Warsaw University of Technology collection during last decade has been discussed. It was discussed matter of collection (in classic and digital version), their development, dependence and autonomy. It was discussed dilemmas about creating library collections. The issue was raised about books collection for academic society, especially for foreign student. The matter was raised about cooperation between the Library and Academy in order to improve quality of education.W artykule omówiono zarządzanie księgozbiorem Biblioteki Głównej Politechniki Warszawskiej w kontekście zmian, które zaszły w nim na przestrzeni ostatnich 10 lat. Omówiono księgozbiór tradycyjny (w wersji papierowej) oraz zasoby elektroniczne, ich rozwój oraz wzajemne przenikanie się, zależności i autonomię. Przedstawiono problemy dotyczące kształtowania zasobów Biblioteki. Poruszono kwestie księgozbioru dydaktycznego, w tym dla studentów zagranicznych. Podjęto temat współpracy Biblioteki z Uczelnią w pracach nad polepszeniem jakości kształcenia