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Genetic Dissection Of Complex Category Traits In Saccharomyces Cerevisiae

Posted on:2011-05-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:J R LiFull Text:PDF
GTID:1220330434473104Subject:Genetics
Abstract/Summary:PDF Full Text Request
Phenotypic variation of complex quantitative traits is determined by genetic, environmental factors and their interactions. Genetic dissection of the polygenic variation underlying these traits has emerged as one of the greatest challenges facing geneticists in the century of omics. The cell-cell adhesion, an interactive behavior that exist in many eukaryotic cells, refers to a developmental progress during which cells aggregate and form clumps through adhesion factors locating on cellular surface. Many studies have been focused on factors influencing the cell adhesions including embryonic development, organic metabolism and tumor genesis. Saccharomyces cerevisiae is the simplest eukaryote and provides an idea model for genetic dissection of many complex traits including the aforementioned cellular characters. Yeast cell adhesion has been attributed to genetic control of the FLO gene family, which can be divided into two typical types according to biochemical properties of the proteins involved:cell-cell adhesion and cell-abiotic surface adhesion. The former, also referred as to flocculation, was recognized as the mechanism for cells to separate from the fermentation products (e.g. ethanol), and to launch cooperative behavior to escape from environmental threatening (e.g. nutritive deficiency or high concentration ethanol). The latter causes invasive growth, a key cellular character in cancer metastasis and pathogen’s inflammatory invasion. The significant impacts of the cellular behavior traits on evolutionary biology, medicine and industrious applications have stimulated the great interests of research to understanding the molecular basis of the complex behavior characters of eukaryotic cells.In this thesis, we represent a forward genetic approach to dissect genetic control of cell flocculation and invasive growth in natural populations of budding yeast (S. cerevisiae). We carried out genome-wide screening for quantitative trait loci (QTL) underlying phenotypic variation of flocculation and invasive growth and detected4and3significant QTL respectively. The high-resolution mapping of these QTL has enabled to narrow them into the corresponding QTL genes. Of them, two major genes are novel in addition to the two previously reported flocculation genes, FLO1and FLO8, which encode a cell-surface adhesin and its transcriptional factor respectively. Genetic, biochemical and cellular assays unveiled how these genetic factors have contributed individually and interactively to determine the complex multiple threshold traits of formation of flocculation and induce invasive growth of the eukaryotic cells.
Keywords/Search Tags:flocculation and invasive growth of yeast cells, map-based cloningof QTL genes, functional analyses, Saccharomyces cerevisiae
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