scholarly journals Lack of support for Deuterostomia prompts reinterpretation of the first Bilateria

2020 ◽  
Author(s):  
Paschalia Kapli ◽  
Paschalis Natsidis ◽  
Daniel J. Leite ◽  
Maximilian Fursman ◽  
Nadia Jeffrie ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Tree Reconstruction ◽  
Simulation Experiments ◽  
Animal Evolution ◽  
Internal Branch ◽  
Embryonic Cleavage ◽  
Branch Lengths ◽  
Statistical Support ◽  
The Common ◽  
Molecular Characters

AbstractThe bilaterally symmetric animals (Bilateria) are considered to comprise two monophyletic groups, Protostomia and Deuterostomia. Protostomia contains the Ecdysozoa and the Lophotrochozoa; Deuterostomia contains the Chordata and the Xenambulacraria (Hemichordata, Echinodermata and Xenacoelomorpha). Their names refer to a supposed distinct origin of the mouth (stoma) in the two clades, but these groups have been differentiated by other embryological characters including embryonic cleavage patterns and different ways of forming their mesoderm and coeloms. Deuterostome monophyly is not consistently supported by recent studies. Here we compare support for Protostomia and Deuterostomia using five recently published, phylogenomic datasets. Protostomia is always strongly supported, especially by longer and higher quality genes. Support for Deuterostomia is always equivocal and barely higher than support for paraphyletic alternatives. Conditions that can cause tree reconstruction errors - inadequate models, short internal branch, faster evolving genes, and unequal branch lengths - correlate with statistical support for monophyletic deuterostomes. Simulation experiments show that support for Deuterostomia could be explained by systematic error. A survey of molecular characters supposedly diagnostic of deuterostomes shows many are not valid synapomorphies. The branch between bilaterian and deuterostome common ancestors, if real, is very short. This finding fits with growing evidence suggesting the common ancestor of all Bilateria had many deuterostome characteristics. This finding has important implications for our understanding of early animal evolution and for the interpretation of some enigmatic Cambrian fossils such as vetulicolians and banffiids.

scholarly journals Lack of support for Deuterostomia prompts reinterpretation of the first Bilateria

2021 ◽  
Vol 7 (12) ◽  
pp. eabe2741
Author(s):  
Paschalia Kapli ◽  
Paschalis Natsidis ◽  
Daniel J. Leite ◽  
Maximilian Fursman ◽  
Nadia Jeffrie ◽  
...  
Keyword(s):  
Systematic Error ◽  
Tree Reconstruction ◽  
Simulation Experiments ◽  
Animal Evolution ◽  
Phylogenetic Studies ◽  
Branch Lengths ◽  
Molecular Phylogenetic ◽  
Common Ancestors

The bilaterally symmetric animals (Bilateria) are considered to comprise two monophyletic groups, Protostomia (Ecdysozoa and the Lophotrochozoa) and Deuterostomia (Chordata and the Xenambulacraria). Recent molecular phylogenetic studies have not consistently supported deuterostome monophyly. Here, we compare support for Protostomia and Deuterostomia using multiple, independent phylogenomic datasets. As expected, Protostomia is always strongly supported, especially by longer and higher-quality genes. Support for Deuterostomia, however, is always equivocal and barely higher than support for paraphyletic alternatives. Conditions that cause tree reconstruction errors—inadequate models, short internal branches, faster evolving genes, and unequal branch lengths—coincide with support for monophyletic deuterostomes. Simulation experiments show that support for Deuterostomia could be explained by systematic error. The branch between bilaterian and deuterostome common ancestors is, at best, very short, supporting the idea that the bilaterian ancestor may have been deuterostome-like. Our findings have important implications for the understanding of early animal evolution.

The Possible Common Origin of tRNA and 5S rRNA

1983 ◽  
Vol 38 (5-6) ◽  
pp. 501-504 ◽  
Author(s):  
Mária Ujhelyi
Keyword(s):  
Common Ancestor ◽  
Common Origin ◽  
5S Rrna ◽  
Mitochondrial Trna ◽  
Trna Molecule ◽  
The Common

Seryl tRNA (anticodon GCU) from mammalian mito­chondria shows in comparison to other mitochondrial tRNAs additional special features differing from the generalized tRNA model. When arranged in the tradi­tional cloverleaf form, eight bases fall within the TΨC loop, and the entire dihydrouridine loop is lacking. This seryl tRNA molecule is therefore shorter than other tRNAs. It was originally thought to represent a mito­chondrial analogon of 5 S rRNA and its precise classifica­tion is still disputed. The present studies suggest that this mitochondrial tRNA represents a fossil molecule which is related to the common ancestor of the present tRNA and 5 S rRNA molecules.

scholarly journals Role of the Digestive Gland in Ink Production in Four Species of Sea Hares: An Ultrastructural Comparison

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jeffrey S. Prince ◽  
Paul Micah Johnson
Keyword(s):  
Digestive Gland ◽  
Common Ancestor ◽  
Aplysia Californica ◽  
Digestive Cell ◽  
Digestive Cells ◽  
Sea Hare ◽  
Red Algal ◽  
The Common ◽  
Algal Chloroplast

The ultrastructure of the digestive gland of several sea hare species that produce different colored ink (Aplysia californicaproduces purple ink,A. julianawhite ink,A. parvulaboth white and purple ink, whileDolabrifera dolabriferaproduces no ink at all) was compared to determine the digestive gland’s role in the diet-derived ink production process. Rhodoplast digestive cells and their digestive vacuoles, the site of digestion of red algal chloroplast (i.e., rhodoplast) inA. californica, were present and had a similar ultrastructure in all four species. Rhodoplast digestive cell vacuoles either contained a whole rhodoplast or fragments of one or were empty. These results suggest that the inability to produce colored ink in some sea hare species is not due to either an absence of appropriate digestive machinery, that is, rhodoplast digestive cells, or an apparent failure of rhodoplast digestive cells to function. These results also propose that the digestive gland structure described herein occurred early in sea hare evolution, at least in the common ancestor to the generaAplysiaandDolabrifera. Our data, however, do not support the hypothesis that the loss of purple inking is a synapomorphy of the white-ink-producing subgenusAplysia.

Phylogenetic relations of European shrubby taxa of the genusUsnea

2011 ◽  
Vol 43 (5) ◽  
pp. 427-444 ◽  
Author(s):  
Lauri SAAG ◽  
Tiiu TÕRRA ◽  
Andres SAAG ◽  
Ruth DEL-PRADO ◽  
Tiina RANDLANE
Keyword(s):  
Maximum Parsimony ◽  
Chemical Separation ◽  
Molecular Data ◽  
Beta Tubulin ◽  
Phylogenetic Relations ◽  
Branch Lengths ◽  
Nuclear Its ◽  
Molecular Characters

AbstractThis study focuses on EuropeanUsneaspecies with sorediate shrubby thalli, with the aim to evaluate the morphological and chemical separation of species in the light of molecular data. Twenty-twoUsneaspecies, including widely distributed taxa such asU. diplotypus, U. fulvoreagens, U. glabrescens, U. lapponica, U. subfloridana, U. substerilisandU. wasmuthii, were included in the study using Bayesian and maximum parsimony analyses of nuclear ITS and beta-tubulin sequences. The analyses showed that: 1) most taxa that are morphologically well delimited are also distinct by means of molecular characters, 2) shrubby taxa in the sectionUsneathat are difficult to determine by traditional characters form a group of closely related but still genetically distinct entities, exceptU. diplotypusandU. substeriliswhich appear to be polyphyletic. The branch lengths differed largely between two parts of the ITS tree (sectionsUsneaandCeratinae).Usnea intermediais proposed as the sexually reproducing counterpart for the sorediateU. lapponica. Additionally, some new chemotypes ofUsneaspecies were determined.

scholarly journals Sexual reproduction and genetic exchange in parasitic protists

Parasitology ◽  
2014 ◽  
Vol 142 (S1) ◽  
pp. S120-S127 ◽  
Author(s):  
GARETH D. WEEDALL ◽  
NEIL HALL
Keyword(s):  
Life Cycle ◽  
Genome Sequencing ◽  
Common Ancestor ◽  
Life Cycles ◽  
Animal Disease ◽  
Eukaryotic Evolution ◽  
Sequencing Technology ◽  
Parasite Reproduction ◽  
The Common ◽  
Higher Eukaryotes

SUMMARYA key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a topic of debate for many years. Traditionally, protists were considered to be primitive relatives of the ‘higher’ eukaryotes, which may have diverged prior to the evolution of sex and to reproduce by binary fission. More recent views of eukaryotic evolution suggest that sex, and meiosis, evolved early, possibly in the common ancestor of all eukaryotes. However, detecting sex in these parasites is not straightforward. Recent advances, particularly in genome sequencing technology, have allowed new insights into parasite reproduction. Here, we review the evidence on reproduction in parasitic protists. We discuss protist reproduction in the light of parasitic life cycles and routes of transmission among hosts.

Whole-genome analysis-based phylogeographic investigation of Streptococcus pneumoniae serotype 19A sequence type 320 isolates in Japan.

2021 ◽  
Author(s):  
Satoshi Nakano ◽  
Takao Fujisawa ◽  
Bin Chang ◽  
Yutaka Ito ◽  
Hideki Akeda ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Sampling Bias ◽  
Health Concern ◽  
Recent Common Ancestor ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Identification Rate ◽  
Most Recent Common Ancestor ◽  
The Common ◽  
The U.S

After the introduction of the seven-valent pneumococcal conjugate vaccine, the global spread of multidrug resistant serotype 19A-ST320 strains became a public health concern. In Japan, the main genotype of serotype 19A was ST3111, and the identification rate of ST320 was low. Although the isolates were sporadically detected in both adults and children, their origin remains unknown. Thus, by combining pneumococcal isolates collected in three nationwide pneumococcal surveillance studies conducted in Japan between 2008 and 2020, we analyzed 56 serotype 19A-ST320 isolates along with 931 global isolates, using whole-genome sequencing to uncover the transmission route of the globally distributed clone in Japan. The clone was frequently detected in Okinawa Prefecture, where the U.S. returned to Japan in 1972. Phylogenetic analysis demonstrated that the isolates from Japan were genetically related to those from the U.S.; therefore, the common ancestor may have originated in the U.S. In addition, Bayesian analysis suggested that the time to the most recent common ancestor of the isolates form Japan and the U.S. was approximately the 1990s to 2000, suggesting the possibility that the common ancestor could have already spread in the U.S. before the Taiwan 19F-14 isolate was first identified in a Taiwanese hospital in 1997. The phylogeographical analysis supported the transmission of the clone from the U.S. to Japan, but the analysis could be influenced by sampling bias. These results suggested the possibility that the serotype 19A-ST320 clone had already spread in the U.S. before being imported into Japan.

scholarly journals Comparing the folding landscapes of evolutionarily divergent procaspase-3

2022 ◽  
Author(s):  
Liqi Yao ◽  
Clay Clark
Keyword(s):  
Conformational Change ◽  
Common Ancestor ◽  
Folding Pathway ◽  
Free Energies ◽  
Folding Intermediates ◽  
Effector Caspases ◽  
The Common ◽  
Ph Dependent ◽  
Species Specific ◽  
Dimeric Intermediate

All caspases evolved from a common ancestor and subsequently developed into two general classes, inflammatory or apoptotic caspases. The caspase-hemoglobinase fold has been conserved throughout nearly one billion years of evolution and is utilized for both the monomeric and dimeric subfamilies of apoptotic caspases, called initiator and effector caspases, respectively. We compared the folding and assembly of procaspase-3b from zebrafish to that of human effector procaspases in order to examine the conservation of the folding landscape. Urea-induced equilibrium folding/unfolding of procaspase-3b showed a minimum three-state folding pathway, where the native dimer isomerizes to a partially folded dimeric intermediate, which then unfolds. A partially folded monomeric intermediate observed in the folding landscape of human procaspase-3 is not well-populated in zebrafish procaspase-3b. By comparing effector caspases from different species, we show that the effector procaspase dimer undergoes a pH-dependent conformational change, and that the conformational species in the folding landscape exhibit similar free energies. Together, the data show that the landscape for the caspase-hemoglobinase fold is conserved, yet it provides flexibility for species-specific stabilization or destabilization of folding intermediates resulting in changes in stability. The common pH-dependent conformational change in the native dimer, which yields an enzymatically inactive species, may provide an additional, albeit reversible, mechanism for controlling caspase activity in the cell.

scholarly journals Loss of plastid developmental genes coincides with a reversion to monoplastidy in hornworts

2022 ◽  
Author(s):  
Alexander Istvan MacLeod ◽  
Parth K Raval ◽  
Simon Stockhorst ◽  
Michael Knopp ◽  
Eftychios Frangedakis ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Nuclear Division ◽  
Developmental Pathways ◽  
Ancestral State ◽  
Plastid Division ◽  
Plastid Development ◽  
State Reconstruction ◽  
Transcriptomic Data ◽  
The Common ◽  
Almost All

The first plastid evolved from an endosymbiotic cyanobacterium in the common ancestor of the Archaeplastida. The transformative steps from cyanobacterium to organelle included the transfer of control over developmental processes; a necessity for the host to orchestrate, for example, the fission of the organelle. The plastids of almost all embryophytes divide independent from nuclear division, leading to cells housing multiple plastids. Hornworts, however, are monoplastidic (or near-monoplastidic) and their photosynthetic organelles are a curious exception among embryophytes for reasons such as the occasional presence of pyrenoids. Here we screened genomic and transcriptomic data of eleven hornworts for components of plastid developmental pathways. We find intriguing differences among hornworts and specifically highlight that pathway components involved in regulating plastid development and biogenesis were differentially lost in this group of bryophytes. In combination with ancestral state reconstruction, our data suggest that hornworts have reverted back to a monoplastidic phenotype due to the combined loss of two plastid division-associated genes: ARC3 and FtsZ2.

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