<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Applications of Polylox barcoding to the hematopoietic system"^^ . "Understanding the development of tissues and organs at a single\r\ncell level remains a challenge. In this thesis I present a novel barcoding system\r\nPolylox, recently developed by Hans-Reimer Rodewald and colleagues. Based on\r\nthe loxP-Cre recombination system, Polylox allows endogenous barcoding of single\r\ncells in vivo. Using a Markov chain model for the recombination process, I find\r\nthat n = 1,866,890 individual barcodes can be generated. Due to the structure\r\nof Polylox, barcodes have different generation probabilities. The mathematical\r\nmodel presented in this thesis, calibrated against experimental Polylox data,\r\nallows the assignment of generation probabilities to each observed barcode and\r\nthe selection of informative barcodes based on their generation probabilities for\r\nclonal analyses. Experimental collaborators induced barcodes in hematopoietic\r\nstem cells (HSC) and I analysed the clone size distributions, finding large clone\r\nsizes of up to 3.8% in young mice (< 1 year old) and 21.5% in old mice (2 years old)\r\nof HSC in the adult bone marrow. I show that the appearance of large HSC clones\r\nin older mice is explained by a neutral drift model.\r\nSampling from mature populations of the hematopoietic system revealed that a\r\nvery large proportion of HSC contributes to adult hematopoiesis (85.7%). Additionally,\r\nmany HSC realize multipotency in vivo, yet clustering analysis of barcode\r\nfrequency distributions revealed a fundamental split between myelo- erythroid\r\nand common lymphoid lineage development. These findings support the longheld,\r\nbut currently contested, view of a tree-like hematopoietic structure with few\r\nmajor branches.\r\nThe description of the potential of common myeloid progenitors (CMP) as myeloerythroid\r\nrestricted is largely dependent on transplantation and colony assays.\r\nAnalysis of Polylox data places the CMP compartment downstream of the split inside\r\nthe myelo-erythroid branch and shows the myelo-erythroid potential of CMP.\r\nBy building a mathematical framework that allows the computing of the time\r\nevolution of the moments of barcode clone sizes, I show that Polylox data is consistent\r\nwith previous work by Busch et al. further supporting the tree model of\r\nhematopoiesis.\r\nIn addition to the analyses of single barcodes, I use network analysis techniques\r\non observed barcode sets. The connectivity of barcode sets reflects the proliferative\r\nstate of the system during labelling. I found evidence for a strong proliferative\r\nburst of at least three divisions a day in HSC progenitor cells at the time point of\r\nfetal liver formation at embryonic day 9.5 in the mouse embryo.\r\nPolylox proves to be a valuable technique for fate mapping that is not only applicable\r\nto hematopoiesis but a multitude of systems."^^ . "2020" . . . . . . . "Jens"^^ . "Rößler"^^ . "Jens Rößler"^^ . . . . . . "Applications of Polylox barcoding to the hematopoietic system (PDF)"^^ . . . "thesis.pdf"^^ . . . "Applications of Polylox barcoding to the hematopoietic system (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #27047 \n\nApplications of Polylox barcoding to the hematopoietic system\n\n" . "text/html" . .