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Comparative Genomics Supports Sex and Meiosis in Diverse Amoebozoa.

ABSTRACT: Sex and reproduction are often treated as a single phenomenon in animals and plants, as in these organisms reproduction implies mixis and meiosis. In contrast, sex and reproduction are independent biological phenomena that may or may not be linked in the majority of other eukaryotes. Current evidence supports a eukaryotic ancestor bearing a mating type system and meiosis, which is a process exclusive to eukaryotes. Even though sex is ancestral, the literature regarding life cycles of amoeboid lineages depicts them as asexual organisms. Why would loss of sex be common in amoebae, if it is rarely lost, if ever, in plants and animals, as well as in fungi? One way to approach the question of meiosis in the "asexuals" is to evaluate the patterns of occurrence of genes for the proteins involved in syngamy and meiosis. We have applied a comparative genomic approach to study the occurrence of the machinery for plasmogamy, karyogamy, and meiosis in Amoebozoa, a major amoeboid supergroup. Our results support a putative occurrence of syngamy and meiotic processes in all major amoebozoan lineages. We conclude that most amoebozoans may perform mixis, recombination, and ploidy reduction through canonical meiotic processes. The present evidence indicates the possibility of sexual cycles in many lineages traditionally held as asexual.

SUBMITTER: Hofstatter PG

PROVIDER: S-EPMC6263441 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Comparative Genomics Supports Sex and Meiosis in Diverse Amoebozoa.

Hofstatter Paulo G PG Brown Matthew W MW Lahr Daniel J G DJG

Genome biology and evolution 20181101 11

Sex and reproduction are often treated as a single phenomenon in animals and plants, as in these organisms reproduction implies mixis and meiosis. In contrast, sex and reproduction are independent biological phenomena that may or may not be linked in the majority of other eukaryotes. Current evidence supports a eukaryotic ancestor bearing a mating type system and meiosis, which is a process exclusive to eukaryotes. Even though sex is ancestral, the literature regarding life cycles of amoeboid li ...[more]

PMID: 30380054

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Project description:"Actinobacillus porcitonsillarum" is considered a nonpathogenic member of the Pasteurellaceae family, which phenotypically resembles the pathogen Actinobacillus pleuropneumoniae. Previous studies suggested that "A. porcitonsillarum" may represent a new species closely related to Actinobacillus minor, yet no full genome has been sequenced so far. We implemented the Oxford Nanopore and Illumina sequencing technologies to obtain the highly accurate and complete genome sequence of the "A. porcitonsillarum" strain 9953L55. After validating our de novo assembly strategy by comparing the A. pleuropneumoniae S4074T genome sequence obtained by Oxford Nanopore Technology combined with Illumina reads with a PacBio-sequenced S4074T genome from the NCBI database, we performed comparative analyses of the 9953L55 genome with the A. minor type strain NM305T, A. minor strain 202, and A. pleuropneumoniae S4074T. The 2,263,191 bp circular genome of 9953L55 consisted of 2168 and 2033 predicted genes and proteins, respectively. The lipopolysaccharide cluster resembled the genetic organization of A. pleuropneumoniae serotypes 1, 9, and 11, possibly explaining the positive reactions observed previously in serotyping tests. In contrast to NM305T, we confirmed the presence of a complete apxIICABD operon in 9953L55 and 202 accounting for their hemolytic phenotype and Christie-Atkins-Munch-Petersen (CAMP) reaction positivity. Orthologous gene cluster analysis provided insight into the differential ability of strains of the A. minor/"porcitonsillarum" complex and A. pleuropneumoniae to ferment lactose, raffinose, trehalose, and mannitol. The four strains showed distinct and shared transposable elements, CRISPR/Cas systems, and integrated prophages. Genome comparisons based on average nucleotide identity and in silico DNA-DNA hybridization confirmed the close relationship among strains belonging to the A. minor/"porcitonsillarum" complex compared to other Actinobacillus spp., but also suggested that 9953L55 and 202 belong to the same novel species closely related to A. minor, namely, "A. porcitonsillarum." Recognition of the taxon as a separate species would improve diagnostics and control strategies of pig pleuropneumonia.

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Comparative Genomics Supports Sex and Meiosis in Diverse Amoebozoa.

Publications

Comparative Genomics Supports Sex and Meiosis in Diverse Amoebozoa.

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