If theoretical physicists can seriously entertain canonical "standard models" even for the big-bang generation of the entire universe, why cannot life scientists reach a consensus on how life has emerged and settled on this planet? Scientists are hindered by conceptual gaps between bottom-up inferences (from early Earth geological conditions) and top-down extrapolations (from modern life forms to common ancestral states). This book challenges several widely held assumptions and argues for alternative approaches instead. Primal syntheses (literally or figuratively speaking) are called for in at least five major areas. (1) The first RNA-like molecules may have been selected by solar light as being exceptionally photostable. (2) Photosynthetically active minerals and reduced phosphorus compounds could have efficiently coupled the persistent natural energy flows to the primordial metabolism. (3) Stochastic, uncoded peptides may have kick-started an ever-tightening co-evolution of proteins and nucleic acids. (4) The living fossils from the primeval RNA World thrive within modern cells. (5) From the inherently complex protocellular associations preceding the consolidation of integral genomes, eukaryotic cell organization may have evolved more naturally than simple prokaryote-like life forms. - If this book can motivate dedicated researchers to further explore the alternative mechanisms presented, it will have served its purpose well.

It will be some time beforewe see Relax, there's nothing wrong with the "slime, protoplasm, &c. "generating transpositionpaper. People aren't a new animal. ButI have long readyforthisyet. Istopped publishing regretted that I truckled to public in refereed journals in 1965 because opinion,andusedthePentateuchal therewas nointerest in themaize term of creation,by which I really controlling elements. meant "appeared" by some wholly Barbara McClintockto Mel Green, unknownprocess. It is mere rubbish, 1969 thinking at presentof theorigin of life; onemight as well think of the originof matter. Charles Darwin to James D. Hooker, March29, 1863 Sometimes my students and others have asked me: "what was ?rst in evo- tion - retroviruses or retrotransposons?" Since HowardTemin proposed that retrovirusesevolvedfromretrotransposons(Temin1980;Teminetal. 1995)the other alternative that retroviruses emerged ?rst and were the predecessors of LTR-retrotransposons has since been a controversial issue (Terzian et al. , this BOOK). While DNA-transposons could not have existed in an ancestral R- world by de?nition, sure enough, some arguments de?nitely point towards apre-DNAworldscenarioinwhichretroelementswerethedirectdescendants of the earliest replicators representing the emergence of life. First, these rep- cators likely catalyzed their own or other's replication cycles via the catalytic properties of RNA molecules. After translation had emerged some replicators possibly encoded an RNA polymerase ?rst. This later evolved into reverse transcriptase(RT),i. e. themostprominentkey-factoratthetransitionintothe DNA world. Simultaneously, replicators could also have encoded membrane protein-genessuchastheenvgeneofrecentDNA-proviruses. Membraneswere likely present muchearlier as prebioticoily ?lms that supported theevolution of a prebiotic-protometabolism (Dyson 1999; Grif?ths 2007).

If theoretical physicists can seriously entertain canonical "standard models" even for the big-bang generation of the entire universe, why cannot life scientists reach a consensus on how life has emerged and settled on this planet? Scientists are hindered by conceptual gaps between bottom-up inferences (from early Earth geological conditions) and top-down extrapolations (from modern life forms to common ancestral states). This book challenges several widely held assumptions and argues for alternative approaches instead. Primal syntheses (literally or figuratively speaking) are called for in at least five major areas. (1) The first RNA-like molecules may have been selected by solar light as being exceptionally photostable. (2) Photosynthetically active minerals and reduced phosphorus compounds could have efficiently coupled the persistent natural energy flows to the primordial metabolism. (3) Stochastic, uncoded peptides may have kick-started an ever-tightening co-evolution of proteins and nucleic acids. (4) The living fossils from the primeval RNA World thrive within modern cells. (5) From the inherently complex protocellular associations preceding the consolidation of integral genomes, eukaryotic cell organization may have evolved more naturally than simple prokaryote-like life forms. - If this book can motivate dedicated researchers to further explore the alternative mechanisms presented, it will have served its purpose well.

Once per life cycle, mitotic nuclear divisions are replaced by meiosis I and II reducing chromosome number from the diploid level to a haploid genome and recombining chromosome arms by crossing-over. In animals, all this happens during formation of eggs and sperm in yeasts before spore formation. The mechanisms of reciprocal exchange at crossover/chiasma sites are central to mainstream meiosis. To initiate the meiotic exchange of DNA, surgical cuts are made as a form of calculated damage that subsequently is repaired by homologous recombination. These key events are accompanied by ancillary provisions at the level of chromatin organization, sister chromatid cohesion and differential centromere connectivity. Great progress has been made in recent years in our understanding of these mechanisms. Questions still open primarily concern the placement of and mutual coordination between neighboring crossover events. Of overlapping significance, this book features two comprehensive treatises of enzymes involved in meiotic recombination, as well as the historical conceptualization of meiotic phenomena from genetical experiments. More specifically, these mechanisms are addressed in yeasts as unicellular model eukaryotes. Furthermore, evolutionary subjects related to meiosis are treated."

Once per life cycle, mitotic nuclear divisions are replaced by meiosis I and II reducing chromosome number from the diploid level to a haploid genome and recombining chromosome arms by crossing-over. In animals, all this happens during formation of eggs and sperm in yeasts before spore formation. The mechanisms of reciprocal exchange at crossover/chiasma sites are central to mainstream meiosis. To initiate the meiotic exchange of DNA, surgical cuts are made as a form of calculated damage that subsequently is repaired by homologous recombination. These key events are accompanied by ancillary provisions at the level of chromatin organization, sister chromatid cohesion and differential centromere connectivity. Great progress has been made in recent years in our understanding of these mechanisms. Questions still open primarily concern the placement of and mutual coordination between neighboring crossover events. Of overlapping significance, this book features two comprehensive treatises of enzymes involved in meiotic recombination, as well as the historical conceptualization of meiotic phenomena from genetical experiments. More specifically, these mechanisms are addressed in yeasts as unicellular model eukaryotes. Furthermore, evolutionary subjects related to meiosis are treated."

This fascinating volume addresses the processes and mechanisms taking place in the cell during meiosis and recombination. It covers multicellular eukaryotes such as Drosophila, Arabidopsis, mice and humans. Once per life cycle, mitotic nuclear divisions are replaced by meiosis I and II reducing chromosome number from the diploid level to a haploid genome, reshuffling the homologous chromosomes by their centromeres, and recombining chromosome arms by crossing-over.

This is the first book to give a full overview on genome integrity in different species. From microorganisms to humans, this volume provides an interdisciplinary overview of how genome integrity is maintained. Written by an international panel of experts, the book addresses the connection between genome integrity and human disease.

This is the first book to give a full overview on genome integrity in different species. From microorganisms to humans, this volume provides an interdisciplinary overview of how genome integrity is maintained. Written by an international panel of experts, the book addresses the connection between genome integrity and human disease.

It will be some time beforewe see Relax, there's nothing wrong with the "slime, protoplasm, &c. "generating transpositionpaper. People aren't a new animal. ButI have long readyforthisyet. Istopped publishing regretted that I truckled to public in refereed journals in 1965 because opinion,andusedthePentateuchal therewas nointerest in themaize term of creation,by which I really controlling elements. meant "appeared" by some wholly Barbara McClintockto Mel Green, unknownprocess. It is mere rubbish, 1969 thinking at presentof theorigin of life; onemight as well think of the originof matter. Charles Darwin to James D. Hooker, March29, 1863 Sometimes my students and others have asked me: "what was ?rst in evo- tion - retroviruses or retrotransposons?" Since HowardTemin proposed that retrovirusesevolvedfromretrotransposons(Temin1980;Teminetal. 1995)the other alternative that retroviruses emerged ?rst and were the predecessors of LTR-retrotransposons has since been a controversial issue (Terzian et al. , this BOOK). While DNA-transposons could not have existed in an ancestral R- world by de?nition, sure enough, some arguments de?nitely point towards apre-DNAworldscenarioinwhichretroelementswerethedirectdescendants of the earliest replicators representing the emergence of life. First, these rep- cators likely catalyzed their own or other's replication cycles via the catalytic properties of RNA molecules. After translation had emerged some replicators possibly encoded an RNA polymerase ?rst. This later evolved into reverse transcriptase(RT),i. e. themostprominentkey-factoratthetransitionintothe DNA world. Simultaneously, replicators could also have encoded membrane protein-genessuchastheenvgeneofrecentDNA-proviruses. Membraneswere likely present muchearlier as prebioticoily ?lms that supported theevolution of a prebiotic-protometabolism (Dyson 1999; Grif?ths 2007).