scholarly journals Endosymbiotic theories for eukaryote origin

2015 ◽  
Vol 370 (1678) ◽  
pp. 20140330 ◽  
Author(s):  
William F. Martin ◽  
Sriram Garg ◽  
Verena Zimorski
Keyword(s):  
Evolutionary History ◽  
Eukaryotic Cell ◽  
Facultative Anaerobe ◽  
Eukaryotic Nucleus ◽  
Evolutionary Innovation ◽  
Eukaryote Evolution ◽  
Cell Organization ◽  
Energetic Constraints ◽  
Origin Of Eukaryotes

For over 100 years, endosymbiotic theories have figured in thoughts about the differences between prokaryotic and eukaryotic cells. More than 20 different versions of endosymbiotic theory have been presented in the literature to explain the origin of eukaryotes and their mitochondria. Very few of those models account for eukaryotic anaerobes. The role of energy and the energetic constraints that prokaryotic cell organization placed on evolutionary innovation in cell history has recently come to bear on endosymbiotic theory. Only cells that possessed mitochondria had the bioenergetic means to attain eukaryotic cell complexity, which is why there are no true intermediates in the prokaryote-to-eukaryote transition. Current versions of endosymbiotic theory have it that the host was an archaeon (an archaebacterium), not a eukaryote. Hence the evolutionary history and biology of archaea increasingly comes to bear on eukaryotic origins, more than ever before. Here, we have compiled a survey of endosymbiotic theories for the origin of eukaryotes and mitochondria, and for the origin of the eukaryotic nucleus, summarizing the essentials of each and contrasting some of their predictions to the observations. A new aspect of endosymbiosis in eukaryote evolution comes into focus from these considerations: the host for the origin of plastids was a facultative anaerobe.

scholarly journals The role of archaea in the origin of eukaryotes

2017 ◽  
Vol 15 (4) ◽  
pp. 52-59
Author(s):  
Sergey V. Shestakov
Keyword(s):  
Common Ancestor ◽  
Eukaryotic Cell ◽  
Last Eukaryotic Common Ancestor ◽  
Large Sets ◽  
Open Questions ◽  
Evolutionary Branch ◽  
Origin Of Eukaryotes

A key role of particular evolutionary branch of archaea in the emergence of eukaryotic cell is considered on the basis of phylogenomics. Genomes of recently discovered uncultivated proteoarchaea belonging to Lokiarchaea and Asgard-group contain a large sets of eukaryotic-like genes. This allows to suggest that ancient forms of such archaean could participate in symbiotic fusion with bacteria serving as a mitochondrial progenitor. The open questions concerning properties of LECA (so-called last eukaryotic common ancestor) are discussed in the frame of endosymbiotic hypothesis of eukaryogenesis.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

scholarly journals Gut bacteria are essential for normal cuticle development in herbivorous turtle ants

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christophe Duplais ◽  
Vincent Sarou-Kanian ◽  
Dominique Massiot ◽  
Alia Hassan ◽  
Barbara Perrone ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Nitrogen Assimilation ◽  
Isotope Ratio Mass Spectrometry ◽  
Gut Bacteria ◽  
Resonance Spectroscopy ◽  
Nitrogen Flow ◽  
Isotopic Enrichment ◽  
History Of ◽  
Cuticle Development

AbstractAcross the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle.

Origin and Early Evolution of the Eukaryotic Cell

2021 ◽  
Vol 75 (1) ◽  
Author(s):  
Toni Gabaldón
Keyword(s):  
Current Knowledge ◽  
Eukaryotic Cell ◽  
Early Evolution ◽  
Annual Review ◽  
Publication Date ◽  
Eukaryotic Evolution ◽  
Life Itself ◽  
Metabolic Interactions ◽  
Phylogenomic Analyses ◽  
Origin Of Eukaryotes

The origin of eukaryotes has been defined as the major evolutionary transition since the origin of life itself. Most hallmark traits of eukaryotes, such as their intricate intracellular organization, can be traced back to a putative common ancestor that predated the broad diversity of extant eukaryotes. However, little is known about the nature and relative order of events that occurred in the path from preexisting prokaryotes to this already sophisticated ancestor. The origin of mitochondria from the endosymbiosis of an alphaproteobacterium is one of the few robustly established events to which most hypotheses on the origin of eukaryotes are anchored, but the debate is still open regarding the time of this acquisition, the nature of the host, and the ecological and metabolic interactions between the symbiotic partners. After the acquisition of mitochondria, eukaryotes underwent a fast radiation into several major clades whose phylogenetic relationships have been largely elusive. Recent progress in the comparative analyses of a growing number of genomes is shedding light on the early events of eukaryotic evolution as well as on the root and branching patterns of the tree of eukaryotes. Here I discuss current knowledge and debates on the origin and early evolution of eukaryotes. I focus particularly on how phylogenomic analyses have challenged some of the early assumptions about eukaryotic evolution, including the widespread idea that mitochondrial symbiosis in an archaeal host was the earliest event in eukaryogenesis. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Early origin of sweet perception in the songbird radiation

Science ◽  
2021 ◽  
Vol 373 (6551) ◽  
pp. 226-231 ◽  
Author(s):  
Yasuka Toda ◽  
Meng-Ching Ko ◽  
Qiaoyi Liang ◽  
Eliot T. Miller ◽  
Alejandro Rico-Guevara ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Genetic Basis ◽  
Sensory Biology ◽  
Avian Evolution ◽  
Nectar Feeding ◽  
Evolutionary Radiation ◽  
History Of ◽  
Sensory Convergence ◽  
Early Origin

Early events in the evolutionary history of a clade can shape the sensory systems of descendant lineages. Although the avian ancestor may not have had a sweet receptor, the widespread incidence of nectar-feeding birds suggests multiple acquisitions of sugar detection. In this study, we identify a single early sensory shift of the umami receptor (the T1R1-T1R3 heterodimer) that conferred sweet-sensing abilities in songbirds, a large evolutionary radiation containing nearly half of all living birds. We demonstrate sugar responses across species with diverse diets, uncover critical sites underlying carbohydrate detection, and identify the molecular basis of sensory convergence between songbirds and nectar-specialist hummingbirds. This early shift shaped the sensory biology of an entire radiation, emphasizing the role of contingency and providing an example of the genetic basis of convergence in avian evolution.

scholarly journals Computational modelling of mitotic exit in budding yeast: the role of separase and Cdc14 endocycles

2011 ◽  
Vol 8 (61) ◽  
pp. 1128-1141 ◽  
Author(s):  
P. K. Vinod ◽  
Paula Freire ◽  
Ahmed Rattani ◽  
Andrea Ciliberto ◽  
Frank Uhlmann ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Budding Yeast ◽  
Cell Cycle Control ◽  
Computational Modelling ◽  
Eukaryotic Cell ◽  
Mitotic Exit ◽  
Intuitive Reasoning ◽  
Systematic Analysis ◽  
Systems View

The operating principles of complex regulatory networks are best understood with the help of mathematical modelling rather than by intuitive reasoning. Hereby, we study the dynamics of the mitotic exit (ME) control system in budding yeast by further developing the Queralt's model. A comprehensive systems view of the network regulating ME is provided based on classical experiments in the literature. In this picture, Cdc20–APC is a critical node controlling both cyclin (Clb2 and Clb5) and phosphatase (Cdc14) branches of the regulatory network. On the basis of experimental situations ranging from single to quintuple mutants, the kinetic parameters of the network are estimated. Numerical analysis of the model quantifies the dependence of ME control on the proteolytic and non-proteolytic functions of separase. We show that the requirement of the non-proteolytic function of separase for ME depends on cyclin-dependent kinase activity. The model is also used for the systematic analysis of the recently discovered Cdc14 endocycles. The significance of Cdc14 endocycles in eukaryotic cell cycle control is discussed as well.

Abstract 20: Resident Cardiac Stem Cell Growth Determines the Number of Ventricular Cardiomyocytes in the Mouse Heart

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Barbara Ogórek ◽  
João Ferreira-Martins ◽  
Donato Cappetta ◽  
Alex Matsuda ◽  
Sergio Signore ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Late Gestation ◽  
Primary Data ◽  
Mouse Heart ◽  
Lineage Specification ◽  
Exponential Equation ◽  
Cell Organization ◽  
Parenchymal Cells ◽  
Best Fit

The objective of this study was to determine the role of c-kit-positive cardiac stem cells (CSCs) in the formation of the heart during prenatal life, and immediately after birth. Mice in which EGFP is under the control of the c-kit-promoter were employed to measure the number of CSCs (Ns), the fraction of cycling MCM5-positive CSCs (f) and the length of the cell cycle (Ts) in CSCs. The number of CSCs committed to the myocyte lineage (LCC: lineage committed cells) included myocyte progenitors (c-kit-positive, Nkx2.5-positive cells), myocyte precursors (c-kit-positive, Nkx2.5-positive, and α-sarcomeric actin-positive cells) and replicating amplifying myocytes (c-kit-negative, Nkx2.5-positive, α-sarcomeric actin-positive, and MCM5-positive cells). These variables derived from CSC growth and lineage specification were evaluated to define the rate of formation of terminally differentiated myocytes (r). Based on a hierarchically structured cell organization, the rate of entry (Rs) of CSCs into the cell cycle was computed from Rs = f x (Ns/Ts), and the rate of generation of mature myocytes, r, was obtained from r = Rs x 2 Gt = ((f x Ns)/Ts) x 2 Gt . The exponent Gt defines the number of transit generations, i.e., the number of divisions that one CSC has to go through before it acquires the terminally differentiated myocyte phenotype. To validate this scenario and establish the number of post-mitotic myocytes formed, the primary data listed above were collected at E9, E14, E19 and P1. The number of mature cardiomyocytes generated by 1 CSC in 1 day was 1.1 x 10 3 , 20 x 10 3 , 501 x 10 3 , and 440 x 10 3 at E9, E14, E19 and P1, respectively. The total number of myocytes (Nm) formed from E9 to E14, E19 and P1 was derived from an exponential equation with the best fit to the experimental data: Nm = exp (0.69 x t) where Nm is the number of myocytes and t is time in days. Accordingly, CSCs generated 1 x 10 5 , 1 x 10 6 and 1.8 x 10 6 myocytes at from E9 to E14, E19 and P1, respectively. These values accounted for all parenchymal cells present at mid and late gestation and in the neonatal heart measured morphometrically. Thus, the expansion of the myocyte mass during embryonic, fetal and immediate postnatal development is controlled by activation, growth and differentiation of resident c-kit-positive CSCs.

Adaptive convergent evolution of genome proofreading in SARS-CoV2: insights into the Eigen’s paradox

2021 ◽  
Author(s):  
Keerthic Aswin ◽  
Srinivasan Ramachandran ◽  
Vivek T Natarajan
Keyword(s):  
Convergent Evolution ◽  
Genome Stability ◽  
Evolutionary History ◽  
Rna Binding ◽  
Phylogenetic Analyses ◽  
Comparative Genome Analysis ◽  
The Family ◽  
History Of ◽  
Key Residues

AbstractEvolutionary history of coronaviruses holds the key to understand mutational behavior and prepare for possible future outbreaks. By performing comparative genome analysis of nidovirales that contain the family of coronaviruses, we traced the origin of proofreading, surprisingly to the eukaryotic antiviral component ZNFX1. This common recent ancestor contributes two zinc finger (ZnF) motifs that are unique to viral exonuclease, segregating them from DNA proof-readers. Phylogenetic analyses indicate that following acquisition, genomes of coronaviruses retained and further fine-tuned proofreading exonuclease, whereas related families harbor substitution of key residues in ZnF1 motif concomitant to a reduction in their genome sizes. Structural modelling followed by simulation suggests the role of ZnF in RNA binding. Key ZnF residues strongly coevolve with replicase, and the helicase involved in duplex RNA unwinding. Hence, fidelity of replication in coronaviruses is a result of convergent evolution, that enables maintenance of genome stability akin to cellular proofreading systems.

Love, the Brain, and Becoming Human

2019 ◽  
pp. 44-71
Author(s):  
Riane Eisler
Keyword(s):  
Human Brain ◽  
Human Development ◽  
Human Evolution ◽  
Evolutionary History ◽  
Negative Effects ◽  
New Perspective ◽  
The Brain ◽  
The Continuum

This chapter introduces a new perspective on the role of love in human evolution and human development. The bonds of love, whether between parent and child, lovers, or close friends, may all have a common biological root, activating neurochemicals that make us feel good. Like other human capacities, such as consciousness, learning, and creativity, love has a long and fascinating evolutionary history. Indeed, the evolution of love appears to be integral to the development of our human brain and hence to much that distinguishes us from other species. Moreover, love plays a vital, though still largely unrecognized, role in human development, with evidence accumulating about the negative effects of love deprivation as well as the benefits of love. But whether or not our needs for meaning and love are met, and whether or not our capacities for creativity and love are expressed, are largely determined by the interaction of biology and culture—specifically, the degree to which a culture or subculture orients to the partnership or domination end of the continuum.

scholarly journals Morphological stasis in the first myxomycete from the Mesozoic, and the likely role of cryptobiosis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jouko Rikkinen ◽  
David A. Grimaldi ◽  
Alexander R. Schmidt
Keyword(s):  
Evolutionary History ◽  
Molecular Data ◽  
Fruiting Bodies ◽  
Ecological Adaptations ◽  
Environmental Selection ◽  
Morphological Stasis ◽  
Ancient Lineage ◽  
History Of ◽  
Spore Mass

AbstractMyxomycetes constitute a group within the Amoebozoa well known for their motile plasmodia and morphologically complex fruiting bodies. One obstacle hindering studies of myxomycete evolution is that their fossils are exceedingly rare, so evolutionary analyses of this supposedly ancient lineage of amoebozoans are restricted to extant taxa. Molecular data have significantly advanced myxomycete systematics, but the evolutionary history of individual lineages and their ecological adaptations remain unknown. Here, we report exquisitely preserved myxomycete sporocarps in amber from Myanmar, ca. 100 million years old, one of the few fossil myxomycetes, and the only definitive Mesozoic one. Six densely-arranged stalked sporocarps were engulfed in tree resin while young, with almost the entire spore mass still inside the sporotheca. All morphological features are indistinguishable from those of the modern, cosmopolitan genus Stemonitis, demonstrating that sporocarp morphology has been static since at least the mid-Cretaceous. The ability of myxomycetes to develop into dormant stages, which can last years, may account for the phenotypic stasis between living Stemonitis species and this fossil one, similar to the situation found in other organisms that have cryptobiosis. We also interpret Stemonitis morphological stasis as evidence of strong environmental selection favouring the maintenance of adaptations that promote wind dispersal.

Sign in / Sign up

Export Citation Format

Share Document