Project description:How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Native Americans diversified into two basal genetic branches around 13 KYA, one in North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians and Australo-Melanesians, the latter possibly through the ancestors of Aleutian Islanders. Putative relict populations in South America, including the historical Pericúes and Fuego-Patagonians, are not directly related to modern Australo-Melanesians.
Project description:Many fungi form complex three-dimensional fruiting bodies, within which the meiotic machinery for sexual spore production has been considered to be largely conserved over evolutionary time. Indeed, much of what we know about meiosis in plant and animal taxa has been deeply informed by studies of meiosis in Saccharomyces and Neurospora. Nevertheless, the genetic basis of fruiting body development and its regulation in relation to meiosis in fungi is barely known, even within the best studied multicellular fungal model Neurospora crassa. We characterized morphological development and genome-wide transcriptomics in the closely related species Neurospora crassa, Neurospora tetrasperma, and Neurospora discreta, across eight stages of sexual development. Despite diverse life histories within the genus, all three species produce vase-shaped perithecia. Transcriptome sequencing provided gene expression levels of 2479 orthologous genes among all three species. Expression of key meiosis genes and sporulation genes, corresponded to developmental differences among these Neurospora species during sexual development. Screening N. crassa knockout crosses of genes selected for their expression differences across species, eight genes, whose functions were previously unknown, are found to be critical for the successful formation of perithecia. The absence of these genes in mutant crosses resulted in either no perithecium formation or in arrested development at an early stage. Our results provide insight into the genetic basis of Neurospora sexual reproduction, which is also of great importance with regard to other multicelluar ascomycetes, including fungal pathogens closely related to Neurospora in the Sordariomycetes, such as Fusarium spp, Magnaporthe oryzae, and Nectria haematococca mRNA were sampled and compared from eight time points across sexual reproduction in three Neurospora species
Project description:Many fungi form complex three-dimensional fruiting bodies, within which the meiotic machinery for sexual spore production has been considered to be largely conserved over evolutionary time. Indeed, much of what we know about meiosis in plant and animal taxa has been deeply informed by studies of meiosis in Saccharomyces and Neurospora. Nevertheless, the genetic basis of fruiting body development and its regulation in relation to meiosis in fungi is barely known, even within the best studied multicellular fungal model Neurospora crassa. We characterized morphological development and genome-wide transcriptomics in the closely related species Neurospora crassa, Neurospora tetrasperma, and Neurospora discreta, across eight stages of sexual development. Despite diverse life histories within the genus, all three species produce vase-shaped perithecia. Transcriptome sequencing provided gene expression levels of 2479 orthologous genes among all three species. Expression of key meiosis genes and sporulation genes, corresponded to developmental differences among these Neurospora species during sexual development. Screening N. crassa knockout crosses of genes selected for their expression differences across species, eight genes, whose functions were previously unknown, are found to be critical for the successful formation of perithecia. The absence of these genes in mutant crosses resulted in either no perithecium formation or in arrested development at an early stage. Our results provide insight into the genetic basis of Neurospora sexual reproduction, which is also of great importance with regard to other multicelluar ascomycetes, including fungal pathogens closely related to Neurospora in the Sordariomycetes, such as Fusarium spp, Magnaporthe oryzae, and Nectria haematococca mRNA were sampled and compared from eight time points across sexual reproduction in three Neurospora species
Project description:Many fungi form complex three-dimensional fruiting bodies, within which the meiotic machinery for sexual spore production has been considered to be largely conserved over evolutionary time. Indeed, much of what we know about meiosis in plant and animal taxa has been deeply informed by studies of meiosis in Saccharomyces and Neurospora. Nevertheless, the genetic basis of fruiting body development and its regulation in relation to meiosis in fungi is barely known, even within the best studied multicellular fungal model Neurospora crassa. We characterized morphological development and genome-wide transcriptomics in the closely related species Neurospora crassa, Neurospora tetrasperma, and Neurospora discreta, across eight stages of sexual development. Despite diverse life histories within the genus, all three species produce vase-shaped perithecia. Transcriptome sequencing provided gene expression levels of 2479 orthologous genes among all three species. Expression of key meiosis genes and sporulation genes, corresponded to developmental differences among these Neurospora species during sexual development. Screening N. crassa knockout crosses of genes selected for their expression differences across species, eight genes, whose functions were previously unknown, are found to be critical for the successful formation of perithecia. The absence of these genes in mutant crosses resulted in either no perithecium formation or in arrested development at an early stage. Our results provide insight into the genetic basis of Neurospora sexual reproduction, which is also of great importance with regard to other multicelluar ascomycetes, including fungal pathogens closely related to Neurospora in the Sordariomycetes, such as Fusarium spp, Magnaporthe oryzae, and Nectria haematococca
Project description:Many fungi form complex three-dimensional fruiting bodies, within which the meiotic machinery for sexual spore production has been considered to be largely conserved over evolutionary time. Indeed, much of what we know about meiosis in plant and animal taxa has been deeply informed by studies of meiosis in Saccharomyces and Neurospora. Nevertheless, the genetic basis of fruiting body development and its regulation in relation to meiosis in fungi is barely known, even within the best studied multicellular fungal model Neurospora crassa. We characterized morphological development and genome-wide transcriptomics in the closely related species Neurospora crassa, Neurospora tetrasperma, and Neurospora discreta, across eight stages of sexual development. Despite diverse life histories within the genus, all three species produce vase-shaped perithecia. Transcriptome sequencing provided gene expression levels of 2479 orthologous genes among all three species. Expression of key meiosis genes and sporulation genes, corresponded to developmental differences among these Neurospora species during sexual development. Screening N. crassa knockout crosses of genes selected for their expression differences across species, eight genes, whose functions were previously unknown, are found to be critical for the successful formation of perithecia. The absence of these genes in mutant crosses resulted in either no perithecium formation or in arrested development at an early stage. Our results provide insight into the genetic basis of Neurospora sexual reproduction, which is also of great importance with regard to other multicelluar ascomycetes, including fungal pathogens closely related to Neurospora in the Sordariomycetes, such as Fusarium spp, Magnaporthe oryzae, and Nectria haematococca
Project description:Heterochromatin is a specialized form of chromatin that restricts access to DNA and inhibits genetic processes, including transcription and recombination. In Neurospora crassa, constitutive heterochromatin is characterized by trimethylation of lysine 9 on histone H3, hypoacetylation of histones, and DNA methylation. Here we explore whether the conserved histone demethylase, lysine-specific demethylase 1 (LSD1), regulates heterochromatin in Neurospora, and if so, how. Though LSD1 is implicated in heterochromatin regulation, its function is inconsistent across different systems; orthologs of LSD1 have been shown to either promote or antagonize heterochromatin expansion by removing H3K4me or H3K9me respectively. We identify three members of the Neurospora LSD complex (LSDC): LSD1, PHF1, and BDP-1, and strains deficient for any exhibit variable spreading of heterochromatin and establishment of new heterochromatin domains dispersed across the genome. Heterochromatin establishment outside of canonical domains in Neurospora share the unusual characteristic of DNA methylation-dependent H3K9me3; typically, H3K9me3 establishment is independent of DNA methylation. Consistent with this, the hyper-H3K9me3 phenotype of LSD1 knock-out strains is dependent on the presence of DNA methylation, as well as HCHC-mediated histone deacetylation, suggesting spreading is dependent on some feedback mechanism. Altogether, our results suggest LSD1 works in opposition to HCHC to maintain proper heterochromatin boundaries.
Project description:Expression profiling of the three clonotypic lineages dominating T. gondii populations in North America and Europe provides a first comprehensive view of the parasite transcriptome.
2010-02-02 | GSE20145 | GEO
Project description:Ceratina Population Genetics Across Eastern North America