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Origin of the foraminifera.

ABSTRACT: We report nuclear small-subunit rDNA sequences for two species of the benthic foraminifer Ammonia. Because of their abundance in present and past seas, the foraminifera are a very important group of organisms used in a wide range of geologic studies; however, the ancestry of this group was, until now, unknown. Difficulties in purifying foraminiferal DNA and avoiding PCR contamination led us to develop DNA.DNA in situ hybridization techniques to verify our sequence data. Phylogenetic analysis of verified foraminiferal DNA sequence indicates these taxa are a divergent, "alveolate" lineage, within the major eukaryotic radiation. Our findings cast doubt upon the assumption that all foraminifera are derived from an amoebalike ancestor. Cytological features and the DNA sequences presented herein suggest that the foraminifera were derived from a heterokaryotic flagellated marine protist, probably sometime in the later Proterozoic.

SUBMITTER: Wray CG

PROVIDER: S-EPMC42833 | biostudies-other | 1995 Jan

REPOSITORIES: biostudies-other

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Origin of the foraminifera.

Wray C G CG Langer M R MR DeSalle R R Lee J J JJ Lipps J H JH

Proceedings of the National Academy of Sciences of the United States of America 19950101 1

We report nuclear small-subunit rDNA sequences for two species of the benthic foraminifer Ammonia. Because of their abundance in present and past seas, the foraminifera are a very important group of organisms used in a wide range of geologic studies; however, the ancestry of this group was, until now, unknown. Difficulties in purifying foraminiferal DNA and avoiding PCR contamination led us to develop DNA.DNA in situ hybridization techniques to verify our sequence data. Phylogenetic analysis of ...[more]

PMID: 7816805

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Origin

Project description:metagenome

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2015-10-14 | GSE68347 | GEO

Local origin or external input: modern horse origin in East Asia.

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Microparticles in Peritoneal Carcinomatosis of Colorectal Origin

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Project description:The mechanisms by which entire programs of gene regulation emerged during evolution are poorly understood. Neuronal microexons represent the most conserved class of alternative splicing in vertebrates and are critical for proper brain development and function. Here, we discover neural microexon programs in non-vertebrate species and trace their origin to bilaterian ancestors through the emergence of a previously uncharacterized ‘enhancer of microexons' (eMIC) protein domain. The eMIC domain originated as an alternative, neural-enriched splice isoform of the pan-eukaryotic Srrm2/SRm300 splicing factor gene, and subsequently became fixed in the vertebrate and neuronal-specific splicing regulator Srrm4/nSR100 and its paralog Srrm3. Remarkably, the eMIC domain is necessary and sufficient for microexon splicing, and functions by interacting with the earliest components required for exon recognition. The emergence of a novel domain with restricted expression in the nervous system thus resulted in the evolution of splicing programs that contributed to qualitatively expand neuronal molecular complexity in bilaterians.

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