Motility of Dictyostelium discoideum cells studied within the framework of a generalized Langevin model

Analizirana je migracija stanica dvaju sojeva D. discoideum, divljeg tipa AX2 i stanica deficijentnih za korteksiline, u različitim fazama životnog ciklusa – vegetativnoj i agregacijski kompetentnoj fazi. Nenadziranom klasifikacijom svih promatranih stanica identificirane su tri skupine koje se razlikuju prvenstveno po srednjoj brzini kretanja i niskofrekventnom području u periodogramu vektora brzine. Za svaku podskupinu stanica identificiranu unutar pojedine biološke populacije određeni su parametri Langevinovog modela proširenog memorijskim članom

Collective signalling drives rapid jumping between cell states

Development can proceed in "fits and starts", with rapid transitions between cell states involving concerted transcriptome-wide changes in gene expression. However, it is not clear how these transitions are regulated in complex cell populations, in which cells receive multiple inputs. We address this issue using Dictyostelium cells undergoing development in their physiological niche. A continuous single cell transcriptomics time series identifies a sharp "jump" in global gene expression marking functionally different cell states. By simultaneously imaging the physiological dynamics of transcription and signalling, we show the jump coincides with the onset of collective oscillations of cAMP. Optogenetic control of cAMP pulses shows that different jump genes respond to distinct dynamic features of signalling. Late jump gene expression changes are almost completely dependent on cAMP, while transcript changes at the onset of the jump require additional input. The coupling of collective signalling with gene expression is a potentially powerful strategy to drive robust cell state transitions in heterogeneous signalling environments. Based on the context of the jump, we also conclude that sharp gene expression transitions may not be sufficient for commitment

Clearing the slate: RNA turnover to enable cell state switching?

The distribution of mRNA in tissue is determined by the balance between transcription and decay. Understanding the control of RNA decay during development has been somewhat neglected compared with transcriptional control. Here, we explore the potential for mRNA decay to trigger rapid cell state transitions during development, comparing a bistable switch model of cell state conversion with experimental evidence from different developmental systems. We also consider another potential role for large-scale RNA decay that has emerged from studies of stress-induced cell state transitions, in which removal of mRNA unblocks the translation machinery to prioritise the synthesis of proteins that establish the new cell state

Skład olejku eterycznego sosny pospolitej (Pinus sylvestris L.) oraz relacje roślina-owad

A review of methods of isolation, chemical composition and biological activity of essential oil of different organs of Scots pine (Pinus sylvestris) was presented. The data on relation between herbivorous insects and plant were also reviewed.Przedstawiono przegląd literatury dotyczącej metod izolowania, składu chemicznego oraz właściwości biologicznych olejku eterycznego z różnych organów sosny pospolitej (Pinus sylvestris). Omówiono interakcje między rośliną a jej szkodnikami - roślinożernymi owadami