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.

scholarly journals Structural characterization of a Thorarchaeota profilin indicates eukaryotic-like features but with an extended N-terminus

2021 ◽  
Author(s):  
Celestine N Chi ◽  
Ravi Teja Inturi ◽  
Sandra Martinez Lara ◽  
Mahmoud Darweesh
Keyword(s):  
Common Ancestor ◽  
Three Dimensional ◽  
Eukaryotic Cell ◽  
Dimensional Structure ◽  
Resonance Spectroscopy ◽  
Last Eukaryotic Common Ancestor ◽  
Rigid Core ◽  
N Terminus ◽  
Metagenomics Analysis

The emergence of the first eukaryotic cell was preceded by evolutionary events which are still highly debatable. Recently, comprehensive metagenomics analysis has uncovered that the Asgard super-phylum is the closest yet known archaea host of eukaryotes. However, it remains to be established if a large number of eukaryotic signature proteins predicated to be encoded by the Asgard super-phylum are functional at least, in the context of a eukaryotic cell. Here, we determined the three-dimensional structure of profilin from Thorarchaeota by nuclear magnetic resonance spectroscopy and show that this profilin has a rigid core with a flexible N-terminus which was previously implicated in polyproline binding. In addition, we also show that thorProfilin co-localizes with eukaryotic actin in cultured HeLa cells. This finding reaffirm the notion that Asgardean encoded proteins possess eukaryotic-like characteristics and strengthen likely existence of a complex cytoskeleton already in a last eukaryotic common ancestor

scholarly journals The role of mitochondrial energetics in the origin and diversification of eukaryotes

2021 ◽  
Author(s):  
Paul E Schavemaker ◽  
Sergio A Munoz-Gomez
Keyword(s):  
Cell Surface ◽  
Surface Area ◽  
Energy Demand ◽  
Common Ancestor ◽  
Eukaryotic Cell ◽  
Cell Surfaces ◽  
Energy Excess ◽  
Potential Factors ◽  
Cell Volumes

The origin of eukaryotic cell size and complexity is thought by some to have required an energy excess provided by mitochondria, whereas others claim that mitochondria provide no energetic boost to eukaryotes. Recent observations show that energy demand scales continuously and linearly with cell volume across both prokaryotes and eukaryotes, and thus suggest that eukaryotes do not have an increased energetic capacity over prokaryotes. However, amounts of respiratory membranes and ATP synthases scale super-linearly with cell surface area. Furthermore, the energetic consequences of the contrasting genomic designs between prokaryotes and eukaryotes have yet to be precisely quantified. Here, we investigated (1) potential factors that affect the cell volumes at which prokaryotes become surface area-constrained, and (2) the amount of energy that is divested to increasing amounts of DNA due to the contrasting genomic designs of prokaryotes and eukaryotes. Our analyses suggest that prokaryotes are not necessarily constrained by their cell surfaces at cell volumes of 100-103 µm3, and that the genomic design of eukaryotes is only slightly advantageous at genomes sizes of 106-107 bp. This suggests that eukaryotes may have first evolved without the need for mitochondria as these ranges hypothetically encompass the Last Eukaryote Common Ancestor and its proto-eukaryotic ancestors. However, our analyses also show that increasingly larger and fast-dividing prokaryotes would have a shortage of surface area devoted to respiration and would disproportionally divest more energy to DNA synthesis at larger genome sizes. We thus argue that, even though mitochondria may not have been required by the first eukaryotes, the successful diversification of eukaryotes into larger and more active cells was ultimately contingent upon the origin of mitochondria.

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 first eukaryotic kinome tree illuminates the dynamic history of present-day kinases

2020 ◽  
Author(s):  
Leny M. van Wijk ◽  
Berend Snel
Keyword(s):  
Phylogenetic Trees ◽  
Evolutionary History ◽  
Evolutionary Dynamics ◽  
Common Ancestor ◽  
Cell Signalling ◽  
Eukaryotic Cell ◽  
Functional Information ◽  
Last Eukaryotic Common Ancestor ◽  
History Of ◽  
Human Kinome

AbstractEukaryotic Protein Kinases (ePKs) are essential for eukaryotic cell signalling. Several phylogenetic trees of the ePK repertoire of single eukaryotes have been published, including the human kinome tree. However, a eukaryote-wide kinome tree was missing due to the large number of kinases in eukaryotes. Using a pipeline that overcomes this problem, we present here the first eukaryotic kinome tree. The tree reveals that the Last Eukaryotic Common Ancestor (LECA) possessed at least 92 ePKs, much more than previously thought. The retention of these LECA ePKs in present-day species is highly variable. Fourteen human kinases with unresolved placement in the human kinome tree were found to originate from three known ePK superfamilies. Further analysis of ePK superfamilies shows that they exhibit markedly diverse evolutionary dynamics between the LECA and present-day eukaryotes. The eukaryotic kinome tree thus unveils the evolutionary history of ePKs, but the tree also enables the transfer of functional information between related kinases.

scholarly journals Heimdallarchaea encodes profilin with eukaryotic-like actin regulation and polyproline binding

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Sabeen Survery ◽  
Fredrik Hurtig ◽  
Syed Razaul Haq ◽  
Jens Eriksson ◽  
Lionel Guy ◽  
...  
Keyword(s):  
Exact Sequence ◽  
Actin Polymerization ◽  
Common Ancestor ◽  
3D Structure ◽  
Eukaryotic Cell ◽  
Cellular Biology ◽  
Eukaryotic Lineage ◽  
Last Eukaryotic Common Ancestor ◽  
Sequence Of Events

AbstractIt is now widely accepted that the first eukaryotic cell emerged from a merger of an archaeal host cell and an alphaproteobacterium. However, the exact sequence of events and the nature of the cellular biology of both partner cells is still contentious. Recently the structures of profilins from some members of the newly discovered Asgard superphylum were determined. In addition, it was found that these profilins inhibit eukaryotic rabbit actin polymerization and that this reaction is regulated by phospholipids. However, the interaction with polyproline repeats which are known to be crucial for the regulation of profilin:actin polymerization was found to be absent for these profilins and was thus suggested to have evolved later in the eukaryotic lineage. Here, we show that Heimdallarchaeota LC3, a candidate phylum within the Asgard superphylum, encodes a putative profilin (heimProfilin) that interacts with PIP2 and its binding is regulated by polyproline motifs, suggesting an origin predating the rise of the eukaryotes. More precisely, we determined the 3D-structure of Heimdallarchaeota LC3 profilin and show that this profilin is able to: i) inhibit eukaryotic actin polymerization in vitro; ii) bind to phospholipids; iii) bind to polyproline repeats from enabled/vasodilator‐stimulated phosphoprotein; iv) inhibit actin from Heimdallarchaeota from polymerizing into filaments. Our results therefore provide hints of the existence of a complex cytoskeleton already in last eukaryotic common ancestor.

scholarly journals Farm Animals Are Long Away from Natural Behavior: Open Questions and Operative Consequences on Animal Welfare

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 724
Author(s):  
Alberto Cesarani ◽  
Giuseppe Pulina
Keyword(s):  
Animal Welfare ◽  
Farm Animal ◽  
Farm Animals ◽  
Natural State ◽  
Natural Behavior ◽  
Welfare Assessment ◽  
Open Questions ◽  
Naive Approach

The concept of welfare applied to farm animals has undergone a remarkable evolution. The growing awareness of citizens pushes farmers to guarantee the highest possible level of welfare to their animals. New perspectives could be opened for animal welfare reasoning around the concept of domestic, especially farm, animals as partial human artifacts. Therefore, it is important to understand how much a particular behavior of a farm animal is far from the natural one of its ancestors. This paper is a contribution to better understand the role of genetics of the farm animals on their behavior. This means that the naïve approach to animal welfare regarding returning animals to their natural state should be challenged and that welfare assessment should be considered.

scholarly journals miR-205 in Breast Cancer: State of the Art

2020 ◽  
Vol 22 (1) ◽  
pp. 27
Author(s):  
Ilaria Plantamura ◽  
Alessandra Cataldo ◽  
Giulia Cosentino ◽  
Marilena V. Iorio
Keyword(s):  
Breast Cancer ◽  
Cancer Progression ◽  
Normal Breast ◽  
Response To Therapy ◽  
Aberrant Expression ◽  
Open Questions ◽  
Tumor Tissues ◽  
Breast Physiology ◽  
Cancer Types

Despite its controversial roles in different cancer types, miR-205 has been mainly described as an oncosuppressive microRNA (miRNA), with some contrasting results, in breast cancer. The role of miR-205 in the occurrence or progression of breast cancer has been extensively studied since the first evidence of its aberrant expression in tumor tissues versus normal counterparts. To date, it is known that the expression of miR-205 in the different subtypes of breast cancer is decreasing from the less aggressive subtype, estrogen receptor/progesterone receptor positive breast cancer, to the more aggressive, triple negative breast cancer, influencing metastasis capability, response to therapy and patient survival. In this review, we summarize the most important discoveries that have highlighted the functional role of this miRNA in breast cancer initiation and progression, in stemness maintenance, in the tumor microenvironment, its potential role as a biomarker and its relevance in normal breast physiology—the still open questions. Finally, emerging evidence reveals the role of some lncRNAs in breast cancer progression as sponges of miR-205. Here, we also reviewed the studies in this field.

In silico analysis of selenoprotein N (Gallus gallus): absence of EF-hand motif and the role of CUGS-helix domain in antioxidant protection

Metallomics ◽  
2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Shi-Yong Zhu ◽  
Li-Li Liu ◽  
Yue-Qiang Huang ◽  
Xiao-Wei Li ◽  
Milton Talukder ◽  
...  
Keyword(s):  
In Silico ◽  
Common Ancestor ◽  
In Silico Analysis ◽  
Antioxidant Protection ◽  
Jnk Pathway ◽  
Downstream Target ◽  
Ef Hand ◽  
Silico Analysis

Abstract Selenoprotein N (SEPN1) is critical to the normal muscular physiology. Mutation of SEPN1 can raise congenital muscular disorder in human. It is also central to maturation and structure of skeletal muscle in chicken. However, human SEPN1 contained an EF-hand motif, which was not found in chicken. And the biochemical and molecular characterization of chicken SEPN1 remains unclear. Hence, protein domains, transcription factors, and interactions of Ca2+ in SEPN1 were analyzed in silico to provide the divergence and homology between chicken and human in this work. The results showed that vertebrates’ SEPN1 evolved from a common ancestor. Human and chicken's SEPN1 shared a conserved CUGS-helix domain with function in antioxidant protection. SEPN1 might be a downstream target of JNK pathway, and it could respond to multiple stresses. Human's SEPN1 might not combine with Ca2+ with a single EF-hand motif in calcium homeostasis, and chicken SEPN1 did not have the EF-hand motif in the prediction, indicating the EF-hand motif malfunctioned in chicken SEPN1.

scholarly journals How Can Psychological Science Help Counter the Spread of Fake News?

2021 ◽  
Vol 24 ◽  
Author(s):  
Sander van der Linden ◽  
Jon Roozenbeek ◽  
Rakoen Maertens ◽  
Melisa Basol ◽  
Ondřej Kácha ◽  
...  
Keyword(s):  
Research Agenda ◽  
Source Credibility ◽  
Fake News ◽  
Intervention Effectiveness ◽  
Motivated Cognition ◽  
Individual Level ◽  
Psychological Science ◽  
Open Questions ◽  
The Individual

Abstract In recent years, interest in the psychology of fake news has rapidly increased. We outline the various interventions within psychological science aimed at countering the spread of fake news and misinformation online, focusing primarily on corrective (debunking) and pre-emptive (prebunking) approaches. We also offer a research agenda of open questions within the field of psychological science that relate to how and why fake news spreads and how best to counter it: the longevity of intervention effectiveness; the role of sources and source credibility; whether the sharing of fake news is best explained by the motivated cognition or the inattention accounts; and the complexities of developing psychometrically validated instruments to measure how interventions affect susceptibility to fake news at the individual level.

Introgression between non-sister species of honeyeaters (Aves: Meliphagidae) several million years after speciation

2019 ◽  
Vol 128 (3) ◽  
pp. 583-591
Author(s):  
Leo Joseph ◽  
Alex Drew ◽  
Ian J Mason ◽  
Jeffrey L Peters
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Sex Chromosomes ◽  
Common Ancestor ◽  
Sister Species ◽  
Species Boundaries ◽  
North Eastern ◽  
The City

Abstract We reassessed whether two parapatric non-sister Australian honeyeater species (Aves: Meliphagidae), varied and mangrove honeyeaters (Gavicalis versicolor and G. fasciogularis, respectively), that diverged from a common ancestor c. 2.5 Mya intergrade in the Townsville area of north-eastern Queensland. Consistent with a previous specimen-based study, by using genomics methods we show one-way gene flow for autosomal but not Z-linked markers from varied into mangrove honeyeaters. Introgression barely extends south of the area of parapatry in and around the city of Townsville. While demonstrating the long-term porosity of species boundaries over several million years, our data also suggest a clear role of sex chromosomes in maintaining reproductive isolation.

Sign in / Sign up

Export Citation Format

Share Document