Metabolic Contributions of an Alphaproteobacterial Endosymbiont in the Apicomplexan Cardiosporidium cionae

Apicomplexa is a diverse protistan phylum composed almost exclusively of metazoan-infecting parasites, including the causative agents of malaria, cryptosporidiosis, and toxoplasmosis. A single apicomplexan genus, Nephromyces, was described in 2010 as a mutualist partner to its tunicate host. Here we present genomic and transcriptomic data from the parasitic sister species to this mutualist, Cardiosporidium cionae, and its associated bacterial endosymbiont. Cardiosporidium cionae and Nephromyces both infect tunicate hosts, localize to similar organs within these hosts, and maintain bacterial endosymbionts. Though many other protists are known to harbor bacterial endosymbionts, these associations are completely unknown in Apicomplexa outside of the Nephromycidae clade. Our data indicate that a vertically transmitted α-proteobacteria has been retained in each lineage since Nephromyces and Cardiosporidium diverged. This α-proteobacterial endosymbiont has highly reduced metabolic capabilities, but contributes the essential amino acid lysine, and essential cofactor lipoic acid to C. cionae. This partnership likely reduces resource competition with the tunicate host. However, our data indicate that the contribution of the single α-proteobacterial endosymbiont in C. cionae is minimal compared to the three taxa of endosymbionts present in the Nephromyces system, and is a potential explanation for the virulence disparity between these lineages

\u3cem\u3eNephromyces\u3c/em\u3e Encodes a Urate Metabolism Pathway and Predicted Peroxisomes, Demonstrating These Are Not Ancient Losses of Apicomplexans

The Phylum Apicomplexa is a quintessentially parasitic lineage, whose members infect a broad range of animals. One exception to this may be the apicomplexan genus Nephromyces, which has been described as having a mutualistic relationship with its host. Here we analyze transcriptome data from Nephromyces and its parasitic sister taxon, Cardiosporidium, revealing an ancestral purine degradation pathway thought to have been lost early in apicomplexan evolution. The predicted localization of many of the purine degradation enzymes to peroxisomes, and the in silico identification of a full set of peroxisome proteins, indicates that loss of both features in other apicomplexans occurred multiple times. The degradation of purines is thought to play a key role in the unusual relationship between Nephromyces and its host. Transcriptome data confirm previous biochemical results of a functional pathway for the utilization of uric acid as a primary nitrogen source for this unusual apicomplexan

Figure 6 from: Minton RL, McGregor BL, Hayes DM, Paight C, Inoue K (2017) Genetic structuring in the Pyramid Elimia, Elimia potosiensis (Gastropoda: Pleuroceridae), with implications for pleurocerid conservation. Zoosystematics and Evolution 93(2): 437-449. https://doi.org/10.3897/zse.93.14856

The Interior Highlands, in southern North America, possesses a distinct fauna with numerous endemic species. Many freshwater taxa from this area exhibit genetic structuring consistent with biogeography, but this notion has not been explored in freshwater snails. Using mitochondrial 16S DNA sequences and ISSRs, we aimed to examine genetic structuring in the Pyramid Elimia, Elimia potosiensis, at various geographic scales. On a broad scale, maximum likelihood and network analyses of 16S data revealed a high diversity of mitotypes lacking biogeographic patterns across the range of E. potosiensis. On smaller geographic scales, ISSRs revealed significant population structure, even over the distance of a few hundred meters. Unlike other freshwater mollusks like mussels, E. potosiensis showed no evolutionary patterns relating to biogeography. The species does show population-level genetic structure, which may have implications in conservation efforts

Genetic structuring in the Pyramid Elimia, Elimia potosiensis (Gastropoda, Pleuroceridae), with implications for pleurocerid conservation

Volume: 93Start Page: 437End Page: 44

Dry mass (A), protein (B), glycogen (C), and triglycerides (D) content for F₁ from isofemale lines of <i>D. melanogaster</i> raised on HPS or LPS diets.

<p>Values (means ± standard errors) are given for each isofemale line (numbers 1, 2, 3, 5 and 6) and sex, F = female and M = male.</p

ANOVA of glycogen content for F₁ from isofemale lines of <i>D. melanogaster</i> raised on larval diets HPS and LPS.

*<p><i>P</i><0.05,</p>**<p><i>P</i><0.01,</p>***<p><i>P</i><0.001.</p