Publications by authors named "Yonas I Tekle"

This study investigates the genomic characteristics of Echinamoeba silvestris, a small-sized amoeba within the Tubulinea clade of the Amoebozoa supergroup. Despite Tubulinea's significance in various fields, genomic data for this clade have been scarce. E.

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This study investigates the genomic characteristics of , a small-sized amoeba within the Tubulinea clade of the Amoebozoa supergroup. Despite Tubulinea's significance in various fields, genomic data for this clade have been scarce presents the smallest free-living amoeba genome within Tubulinea and Amoebozoa to date. Comparative analysis reveals intriguing parallels with parasitic lineages in terms of genome size and predicted gene numbers, emphasizing the need to understand the consequences of reduced genomes in free-living amoebae.

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Amoebozoa include lineages of diverse ecology, behavior, and morphology. They are assumed to encompass members with the largest genome sizes of all living things, yet genomic studies in the group are limited. , a polymorphic, multinucleate, marine amoeba with a complicated life cycle, has puzzled experts for over a century.

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The supergroup Amoebozoa unites a wide diversity of amoeboid organisms and encompasses enigmatic lineages that have been recalcitrant to modern phylogenetics. Deep divergences, taxonomic placement of some key taxa and character evolution in the group largely remain poorly elucidated or controversial. We surveyed available Amoebozoa genomes and transcriptomes to mine conserved putative single copy genes, which were used to enrich gene sampling and generate the largest supermatrix in the group to date; encompassing 824 genes, including gene sequences not previously analyzed.

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Article Synopsis
  • Scientists studied a type of amoeba called Cochliopodium minus, which is different because it has unusual ways of reproducing and fusing its cells.
  • They created a draft of its genome, which is like a genetic map, and found that it has genes from bacteria, archaea, and viruses mixed in.
  • The researchers also discovered important genes related to reproduction and noted that this amoeba has some similarities to more complex organisms, which can help us understand how sex works in many living things.
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The evolution and diversity of the supergroup Amoebozoa is complex and poorly understood. The supergroup encompasses predominantly amoeboid lineages characterized by extreme diversity in phenotype, behavior and genetics. The study of natural selection, a driving force of diversification, within and among species of Amoebozoa will play a crucial role in understanding the evolution of the supergroup.

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The Amoebozoa, a group containing predominantly amoeboid unicellular protists has been shown to play an important ecological role in controlling environmental bacteria. Amoebozoans not only graze bacteria but also serve as a safe niche for bacterial replication and harbor endosymbiotic bacteria including dangerous human pathogens. Despite their importance, only a few lineages of Amoebozoa have been studied in this regard.

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Sex is a hallmark of eukaryotes but its evolution in microbial eukaryotes is poorly elucidated. Recent genomic studies revealed microbial eukaryotes possess a genetic toolkit necessary for sexual reproduction. However, the mechanism of sexual development in a majority of microbial eukaryotes including amoebozoans is poorly characterized.

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Cochliopodium is a lens-shaped genus of Amoebozoa characterized by a flexible layer of microscopic dorsal scales. Recent taxonomic and molecular studies reported cryptic diversity in this group and suggested that the often-used scale morphology is not a reliable character for species delineation in the genus. Here, we described three freshwater Cochliopodium spp.

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Thecamoebida Smirnov and Cavalier-Smith, 2011 (Discosea, Amoebozoa) has been molecularly understudied. The group until recently consisted of three genera containing species that live in terrestrial or aquatic environments. Here, we describe a fourth genus, Stratorugosa tubuloviscum gen.

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Background: Transcriptome sequencing has become a method of choice for evolutionary studies in microbial eukaryotes due to low cost and minimal sample requirements. Transcriptome data has been extensively used in phylogenomic studies to infer ancient evolutionary histories. However, its utility in studying cryptic species diversity is not well explored.

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Article Synopsis
  • - Microbial eukaryotes like amoeboids have complex life cycles that may involve sexual reproduction, with recent studies suggesting that the Amoebozoa group is ancestrally sexual; however, some have very low detection of sex-related genes.
  • - In the genus Cochliopodium, known for its unique processes of cell fusion and karyogamy, previous findings showed no meiosis genes; this study generates extensive transcriptome data to better understand its genetic basis and lifecycle.
  • - The study identified a higher number of sex-related genes, including previously undetected meiosis genes, revealing that Cochliopodium has the genetic tools for sexual recombination, although the specifics of its fusion and genome reduction mechanisms are still
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Longamoebia is one of the most morphologically diverse member of Amoebozoa. It includes the human pathogen Acanthamoeba, which causes minor skin and serious eye infections as well as fatal central nervous system complications. The taxonomy and phylogeny of Longamoebia is poorly understood partly due to the growing number of molecular studies that report unsuspected affiliations of lineages with extremely different morphotypes in the group.

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Article Synopsis
  • Sex in eukaryotes boosts genetic diversity, but its evolutionary origins, especially in the amoeboid supergroup Amoebozoa, remain unclear; recent studies hint at hidden sexual cycles within this group despite a general belief in their asexuality.* -
  • This study analyzed the genes related to meiosis in 39 different amoebozoans, revealing that while they have many meiosis genes, they lack genes for the synaptonemal complex, which is important for chromosome pairing during meiosis.* -
  • Findings indicate that not only do amoebozoans possess functional sex genes, but also suggest that the group originally had sexual reproduction, challenging the idea that asexuality is the norm and implying
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The cytoskeleton is the hallmark of eukaryotic evolution. The molecular and architectural aspects of the cytoskeleton have been playing a prominent role in our understanding of the origin and evolution of eukaryotes. In this study, we seek to investigate the cytoskeleton architecture and its evolutionary significance in understudied amoeboid lineages belonging to Amoebozoa.

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The majority of amoeboid lineages with flattened body forms are placed under a taxonomic hypothetical class 'Discosea' sensu Smirnov et al. (2011), which encompasses some of the most diverse morphs within Amoebozoa. However, its taxonomy and phylogeny is poorly understood.

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A new species of Cochliopodium isolated from freshwater at Arabia Lake in Lithonia, GA, USA is described based on light microscopic morphology, fine structure, and molecular genetic evidence. Cochliopodium arabianum n. sp.

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The majority of microbial eukaryotes have long been considered asexual, though new evidence indicates sex, or sexual-like (parasexual) behaviors that deviate from the usual union of two gametes, among other variant aspects. Over a dozen amoebozoans are implicated to have sexual stages. However, the exact mechanism by which sex occurs in these lineages remains elusive.

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The diversity of microbial eukaryotes in general and amoeboid lineages in particular is poorly documented. Even though amoeboid lineages are among the most abundant microbes, taxonomic progress in the group has been hindered by the limitations of traditional taxonomy and technical difficultly in studying them. Studies using molecular approaches such as DNA barcoding with cytochrome oxidase I (COI) gene are slowly trickling in for Amoebozoa, and they hopefully will aid in unveiling the true diversity of the group.

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Cochliopodium pentatrifurcatum n. sp. (ATCC(©) 30935(TM) ) is described based on light microscopic morphology, fine structure, and molecular genetic evidence.

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Vaccination has proven effective in controlling many infectious diseases. However, differential effectiveness with regard to pathogen genotype is a frequent reason for failures in vaccine development. Often, insufficient immune response is induced to prevent infection by the diversity of existing serotypes present in pathogenic populations of bacteria.

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A principal objective for phylogenetic experimental design is to predict the power of a data set to resolve nodes in a phylogenetic tree. However, proactively assessing the potential for phylogenetic noise compared with signal in a candidate data set has been a formidable challenge. Understanding the impact of collection of additional sequence data to resolve recalcitrant internodes at diverse historical times will facilitate increasingly accurate and cost-effective phylogenetic research.

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Article Synopsis
  • Epidemiological studies suggest self-interested (Nash) vaccination rates are usually lower than the optimal levels (utilitarian) needed for community health, except for diseases like chickenpox that worsen with age.
  • The choice to vaccinate against chickenpox can negatively impact unvaccinated individuals by raising the average age of infection and increasing the severity, as well as heightening the risk of breakthrough infections in those already vaccinated.
  • A game-theory model applied to the USA and Israel indicates that for chickenpox, achieving herd immunity may require financial subsidies or regulations when vaccination costs are high, while boosting awareness about the vaccine is key when costs are lower.
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An accurate reconstruction of the eukaryotic tree of life is essential to identify the innovations underlying the diversity of microbial and macroscopic (e.g., plants and animals) eukaryotes.

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Six eukaryotic supergroups have been proposed based on both morphological and molecular data. However, some of these supergroups are contentious and the deep relationships among them are poorly resolved. This is due to a limited number of morphological characters and few molecular markers in current use.

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