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Meiosis, the process of forming gametes in preparation for sexual reproduction, has long been a focus of intense study. Meiosis has been studied at the cytological, genetic, molecular and cellular levels. Studies in model systems have revealed common underlying mechanisms while in parallel, studies in diverse organisms have revealed the incredible variation in meiotic mechanisms. This book brings together many of the diverse strands of investigation into this fascinating and challenging field of biology.

Meiosis. --- Reduction division (Genetics) --- Cell division --- Karyokinesis --- Medical genetics

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This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact

cell cycle --- nucleoid --- divisome --- cell division --- cell envelope --- cell shape --- chromosome replication --- macromolecular hyperstructures --- Escherichia coli

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The brain consists of a complex but precisely organized neural network, which provides the structural basis of higher order functions. Such a complex structure originates from a simple pseudostratified neuroepithelium. During the developing mammalian cerebral cortex, a cohort of neural progenitors, located near the ventricle, differentiates into neurons and exhibits multi-step modes of migration toward the pial surface. Tight regulation of neurogenesis and neuronal migration is essential for the determination of the neuron number in adult brains and the proper positioning of excitatory and inhibitory neurons in a specific layer, respectively. In addition, defects in neurogenesis and neuronal migration can cause several neurological disorders, such as microcephaly, periventricular heterotopia and lissencephaly. Recent advances in genetic approaches to study the developing cerebral cortex, as well as the use of a number of novel techniques, particularly in vivo electroporation and time-lapse analyses using explant slice cultures, have significantly increased our understanding of cortical development. These novel techniques have allowed for cell biological analyses of cerebral cortical development in vivo or ex vivo, showing that many cellular events, including endocytosis, cell adhesion, microtubule and actin cytoskeletal regulation, neurotransmitter release, stress response, the consequence of cellular crowding (physical force), dynamics of transcription factors, midbody release and polarity transition are required for neurogenesis and/or neuronal migration. The aim of this research topic is to highlight molecular and cellular mechanisms underlying cerebral cortical development and its related neurological disorders from the cell biological point of views, such as cell division, cell-cycle regulation, cytoskeletal organization, cell adhesion and membrane trafficking. The topic has been organized into three chapters: 1) neurogenesis and cell fate determination, 2) neuronal migration and 3) cortical development-related neurological disorders. We hope that the results and discussions contributed by all authors in this research topic will be broadly useful for further advances in basic research, as well as improvements in the etiology and care of patients suffering from neurological and psychiatric disorders.

Endocytosis --- Cell Cycle --- Periventricular heterotopia --- Lissencephaly --- neuronal migration --- Cell Division --- Cytoskeleton --- Microcephaly --- Neurogenesis --- Cell Adhesion

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Bacterial Physiology was inaugurated as a discipline by the seminal research of Maaløe, Schaechter and Kjeldgaard published in 1958. Their work clarified the relationship between cell composition and growth rate and led to unravel the temporal coupling between chromosome replication and the subsequent cell division by Helmstetter et al. a decade later. Now, after half a century this field has become a major research direction that attracts interest of many scientists from different disciplines. The outstanding question how the most basic cellular processes - mass growth, chromosome replication and cell division - are inter-coordinated in both space and time is still unresolved at the molecular level. Several particularly pertinent questions that are intensively studied follow: (a) what is the primary signal to place the Z-ring precisely between the two replicating and segregating nucleoids? (b) Is this coupling related to the structure and position of the nucleoid itself? (c) How does a bacterium determine and maintain its shape and dimensions? Possible answers include gene expression-based mechanisms, self-organization of protein assemblies and physical principles such as micro-phase separations by excluded volume interactions, diffusion ratchets and membrane stress or curvature. The relationships between biochemical reactions and physical forces are yet to be conceived and discovered. This e-book discusses the above mentioned and related questions. The book also serves as an important depository for state-of-the-art technologies, methods, theoretical simulations and innovative ideas and hypotheses for future testing. Integrating the information gained from various angles will likely help decipher how a relatively simple cell such as a bacterium incorporates its multitude of pathways and processes into a highly efficient self-organized system. The knowledge may be helpful in the ambition to artificially reconstruct a simple living system and to develop new antibacterial drugs.

Chromosome replication --- Bacterial growth --- divisome --- Chromosome Segregation --- Cell Cycle --- Cell Division --- Cell envelope --- size control --- model system Escherichia coli --- nucleoid

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What is life? How, where, and when did life arise? These questions have remained most fascinating over the last hundred years. Systems chemistry is the way to go to better understand this problem and to try and answer the unsolved question regarding the origin of Life. Self-organization, thanks to the role of lipid boundaries, made possible the rise of protocells. The role of these boundaries is to separate and co-locate micro-environments, and make them spatially distinct; to protect and keep them at defined concentrations; and to enable a multitude of often competing and interfering biochemical reactions to occur simultaneously. The aim of this Special Issue is to summarize the latest discoveries in the field of the prebiotic chemistry of biomolecules, self-organization, protocells and the origin of life. In recent years, thousands of excellent reviews and articles have appeared in the literature and some breakthroughs have already been achieved. However, a great deal of work remains to be carried out. Beyond the borders of the traditional domains of scientific activity, the multidisciplinary character of the present Special Issue leaves space for anyone to creatively contribute to any aspect of these and related relevant topics. We hope that the presented works will be stimulating for a new generation of scientists that are taking their first steps in this fascinating field.

origin of life --- peptidyl-transferase center --- pseudo-symmetry --- proto-ribosome --- SymR --- emergence of biological systems --- RNA ligation --- dimerization --- standard genetic codes --- codon assignment --- tRNA --- aminoacyl-tRNA synthetase classes --- thiophene --- acetylene --- transition metal sulfides --- hydrothermal conditions --- early metabolism --- origin-of-life --- prebiotic chemistry --- protein–monosaccharide recognition --- protein–monosaccharide interactions --- FRET analysis --- glycocodon theory --- glucose oxidase --- Mars --- prebiotic chemical evolution --- early Earth --- astrobiology --- CHNOPS --- transition elements --- sample return --- exoplanets --- complex organic molecules --- astrochemistry --- interstellar medium --- molecular ices --- solid state --- protoplanetary disks --- star forming regions --- comets --- vesicles --- division --- urea–urease enzymatic reaction --- bending modulus --- budding --- ADE theory --- dynamic kinetic stability --- cognition --- chemical evolution --- systems chemistry --- metabolism --- network expansion simulation --- temperature --- thermodynamics --- protocell --- compartment --- solid interface --- lipid --- polymerization --- cyclic nucleotides --- autocatalytic set --- osmotic pressure --- cell division --- lipid membrane --- bistable reaction system --- template-directed RNA synthesis --- origin of genetic code --- time order of canonical amino acids --- proto-metabolism --- chirogenesis --- quartz --- amino acids --- radiation damage --- GC×GC-TOFMS --- origins of life --- prebiotic membranes --- protoamphiphiles --- metal ions --- hot springs --- N-acyl amino acid --- analogue conditions --- viroids --- ribozyviruses --- primordial replicators --- ribozymes --- bilayer structure --- molecular dynamics --- aggregation process --- selection --- evolution --- Fenton chemistry --- reduced phosphorus --- pyrophosphate --- chemical complexity --- minerals --- schreibersite --- olivine --- serpentinite --- ulexite --- n/a --- protein-monosaccharide recognition --- protein-monosaccharide interactions --- urea-urease enzymatic reaction