ABSTRACT
Colpomenia sinuosa is a cosmopolitan brown macroalgal species complex and hence a great candidate for evolutionary studies in the marine environment. Since 2009, three major C. sinuosa phylogenetic lineages, subdivided into eight subgroups, have been identified based on cox3 DNA sequences from worldwide collections. However, worldwide sampling remains limited and spotty. To date molecular data from Brazilian C. sinuosa populations have been limited to 10 specimens collected in a single locality. Nonetheless, C. sinuosa populations occur along the entire ~8,000 km Brazilian coast. Consequently, knowledge on population genetic diversity and spatial genetic structuring along most of the Brazilian coastline is nonexistent. To fulfill this gap in knowledge, we performed a phylogeographic analysis of C. sinuosa populations in Brazil. The highly variable cox3 marker was sequenced for 148 individuals collected in 12 localities in Brazil. Results identified two genetically distinct population groups (north vs. south) separated at 20.5° S latitude. Genetic diversity in northern populations is 14.6 and 15.5 times greater than southern populations in terms of haplotype and nucleotide diversity, respectively. Among northern populations, the Bahia state holds the largest genetic diversity. The southern populations had lower genetic diversity and no internal genetic sub-structure suggesting past bottlenecks followed by recent colonization from northern haplotypes. Our results do not indicate recent introductions of foreign haplotypes in Brazil and reinforce the crucial importance of historical and extant allopatric, parapatric, and sympatric processes driving marine macroalgal evolution in the Southwestern Atlantic Ocean.
Subject(s)
DNA, Mitochondrial , Phaeophyceae , Brazil , DNA, Mitochondrial/genetics , Genetic Variation , Genetics, Population , Haplotypes , Phaeophyceae/genetics , Phylogeny , PhylogeographyABSTRACT
The cox3 gene, encoding subunit III of cytochrome c oxidase (Cox3) is in mitochondrial genomes except in chlorophycean algae, where it is localized in the nucleus. Therefore, algae like Chlamydomonas reinhardtii, Polytomella sp. and Volvox carteri, synthesize the Cox3 polypeptide in the cytosol, import it into mitochondria, and integrate it into the cytochrome c oxidase complex. In this work, we followed the in vitro internalization of the Cox3 precursor by isolated, import-competent mitochondria of Polytomella sp. In this colorless alga, the precursor Cox3 protein is synthesized with a long, cleavable, N-terminal mitochondrial targeting sequence (MTS) of 98 residues. In an import time course, a transient Cox3 intermediate was identified, suggesting that the long MTS is processed more than once. The first processing step is sensitive to the metalo-protease inhibitor 1,10-ortophenantroline, suggesting that it is probably carried out by the matrix-located Mitochondrial Processing Protease. Cox3 is readily imported through an energy-dependent import pathway and integrated into the inner mitochondrial membrane, becoming resistant to carbonate extraction. Furthermore, the imported Cox3 protein was assembled into cytochrome c oxidase, as judged by the presence of a labeled band co-migrating with complex IV in Blue Native Electrophoresis. A model for the biogenesis of Cox3 in chlorophycean algae is proposed. This is the first time that the in vitro mitochondrial import of a cytosol-synthesized Cox3 subunit is described.
Subject(s)
Electron Transport Complex IV/metabolism , Mitochondrial Proteins/metabolism , Protein Multimerization , Volvocida/enzymology , Biological Transport, Active , Models, Biological , Protein Processing, Post-Translational , Protein TransportABSTRACT
En 2002 Simmons y colaboradores, de la Universidad Brigham Young de Estados Unidos identificaron una nueva isoforma de ciclooxigenasa la cual fue denominada ciclooxigenasa-3. Esta deriva del gen que codifica la ciclooxigenasa-1, pero es estructural y funcionalmente distinta. Se estableció que su papel es a nivel de la producción de la fiebre, el dolor a nivel central y no a nivel de la inflamación. Al evaluar los medicamentos que producen inhibición farmacológica se identificó al acetaminofen como el más selectivo hacia ella y secundario a estos hallazgos luego de casi 60 años se esclareció el mecanismo de acción de este medicamento.
Ciclooxigenasa 3: the new iso-enzime. In 2002 In 2002, Simmons et al from the Brigham Young University identified a new form of cyclooxygenase, which was called cyclooxygenase-3. This, basically, derives from the cyclooxygenase-1 gene codifier but it differs structurally and functionally from COX-1. It has been established that PGs COX-3 produces fever and central pain but not inflammation. When pharmacological inhibition from several drugs were tested, acetaminophen was identified as the most selective inhibitor. Following this discovery, after 60 years finally the pharmacological mechanism for the acetaminophen was clarified.