Dataset Information

Evolutionary Analysis of Unicellular Species in Chlamydomonadales Through Chloroplast Genome Comparison With the Colonial Volvocine Algae.

ABSTRACT: This study is the first determination of six chloroplast genomes of colonial volvocine algae, Colemanosphaera charkowiensis, Volvulina compacta, Pandorina colemaniae, Pandorina morum, Colemanosphaera angeleri, and Yamagishiella unicocca. Based on 55 chloroplast protein-coding genes, we compared the nonsynonymous (dN) and synonymous (dS) substitution rates between colonial volvocine algae and the other unicellular Chlamydomonadales species. When refer to the dN, we found 27 genes were significantly different, among them, 19 genes were significant higher in unicellular species (FDR-adjusted P < 0.05). When refer to the dS, we found 10 genes were significantly different, among them, 6 genes were significant higher in unicellular species (FDR-adjusted P < 0.05). Then we identified 14 putative fast-evolving genes and 11 putative positively selected genes of unicellular species, we analyzed the function of positively selected sites of the overlap genes of putative fast-evolving and positively selected genes, and found some sites were close to the important functional region of the proteins. Photosynthesis is the process to transform and store solar energy by chloroplast, it plays a vital role in the survival of algae, this study is the first to use the chloroplast genomes to analysis the evolutionary relationship between colonial and unicellular species in Chlamydomonadales. We found more genes have higher substitution rates in unicellular species and proposed that the fast-evolving and positively selected two genes, psbA and psbC, may help to improve the photosynthetic efficiency of unicellular species in Chlamydomonadales.

SUBMITTER: Hu Y

PROVIDER: S-EPMC6591512 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Colonial Volvocine Algae (CVA) are of great significance for biological evolution study, but little is presently known about their biogeographic distribution. Meanwhile, with the impact of climate change and human activities, their effects on the distribution and structures of CVA communities also remain largely unknown. Herein, the biogeography of CVA was investigated in the Yangtze River basin, 172 sampling sites were set up within a catchment area of 1,800,000 km2, and the distribution and community composition of CVA were studied using single-molecule real-time sequencing and metabarcoding technology based on the full-length 18S sequence. In 76 sampling sites, CVA was discovered in two families, eight genera, and nine species. Eudorina and Colemanosphaera were the main dominant genus. Based on the result of the random forest model and Eta-squared value, the distribution of CVA was significantly influenced by water temperature, altitude, and TP. CVA could be suitably distributed at an average water temperature of 22°C, an average TP concentration of 0.06 mg/L, and an altitude lower than 3,920 m. To assess the effects of anthropogenic pollution on the structures and co-occurrence patterns of CVA communities, we used a stress index calculated by 10 environmental factors to divide the CVA community into low and high pollution group. Network analysis showed that greater pollution levels would have a negative impact on the co-occurrence patterns and diversity of the CVA community. Finally, to study the scientific distribution of CVA under current and future climate change scenarios, we analyzed the climate suitability regionalization of CVA with the maximum entropy model based on 19 climatic factors and four climate scenarios from 2021 to 2040 published by CMIP6. Our results reveal the suitable areas of CVA, and temperature is an important environmental factor affecting the distribution of CVA. With the change of climate in the future, the Three Gorges Reservoir Area, Chaohu Lake, and Taihu Lake are still highly suitable areas for CVA, but the habitat of CVA may be fragmented, and more thorough temporal surveys and sampling of the sediment or mud are needed to investigate the fragmentation of CVA.

Project description:BACKGROUND:The evolution of oogamy from isogamy, an important biological event, can be summarized as follows: morphologically similar gametes (isogametes) differentiated into small "male" and large "female" motile gametes during anisogamy, from which immotile female gametes (eggs) evolved. The volvocine green algae represent a model lineage to study this type of sex evolution and show two types of gametic unions: conjugation between isogametes outside the parental colonies (external fertilization during isogamy) and fertilization between small motile gametes (sperm) and large gametes (eggs) inside the female colony (internal fertilization during anisogamy and oogamy). Although recent cultural studies on volvocine algae revealed morphological diversity and molecular genetic data of sexual reproduction, an intermediate type of union between these two gametic unions has not been identified. RESULTS:We identified a novel colonial volvocine genus, Colemanosphaera, which produces bundles of spindle-shaped male gametes through successive divisions of colonial cells. Obligately anisogamous conjugation between male and female motile gametes occurred outside the female colony (external fertilization during anisogamy). This new genus contains 16- or 32-celled spheroidal colonies similar to those of the volvocine genera Yamagishiella and Eudorina. However, Colemanosphaera can be clearly distinguished from these two genera based on its sister phylogenetic position to the enigmatic flattened colonial volvocine Platydorina and external fertilization during anisogamy. Two species of Colemanosphaera were found in a Japanese lake; these species are also distributed in European freshwaters based on a published sequence of an Austrian strain and the original description of Pandorina charkowiensis from Ukraine. CONCLUSIONS:Based on phylogeny and morphological data, this novel genus exhibits a missing link between Platydorina and the typical spheroidal colonial volvocine members such as Pandorina or Yamagishiella. Considering the external obligate anisogamy, oogamy evolution may have been preceded by the transition from external to internal fertilization during anisogamy within the volvocine green algae.

Dataset Information

Evolutionary Analysis of Unicellular Species in Chlamydomonadales Through Chloroplast Genome Comparison With the Colonial Volvocine Algae.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets