A widespread coral-infecting apicomplexan contains a plastid encoding chlorophyll biosynthesis

Abstract

The Apicomplexa are an important group of obligate intracellular parasites that include the causative agents of human diseases like malaria and toxoplasmosis. They evolved from free-living, phototrophic ancestors, and how this transition to parasitism occurred remains an outstanding question. One potential clue lies in coral reefs, where environmental DNA surveys have uncovered several lineages of uncharacterized, basally-branching apicomplexans. Reef-building corals form a well-studied symbiotic relationship with the photosynthetic dinoflagellate Symbiodinium, but identification of other key microbial symbionts of corals has proven elusive. Here, we used community surveys, genomics, and microscopy to identify an apicomplexan lineage, which we name 'corallicola', that was found in high prevalence (>80%) across all major groups of corals. In-situ fluorescence and electron microscopy confirmed that corallicola lives intracellularly within the tissues of the coral gastric cavity, and possesses clear apicomplexan ultrastructural features. We sequenced the plastid genome, which lacked all genes for photosystem proteins, indicating that corallicola harbours a non-photosynthetic plastid (an apicoplast). However, the corallicola plastid differed from all other known apicoplasts because it retains all four genes involved in chlorophyll biosynthesis. Hence, corallicola shares characteristics with both its parasitic and free-living relatives, implicating it as an evolutionary intermediate, and suggesting that a unique ancestral biochemistry likely operated during the transition from phototrophy to parasitism.

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals

“…In addition to the Symbiodiniaceae, there is a diversity of eukaryotes associated with corals that include the apicomplexan-related lineages (ARLs), many of which are largely uncharacterized (Clerissi et al, 2018), but can occur in high prevalence across coral groups (Kirk et al, 2013a,b; Kwong et al, 2018) Further, the discovery of apicomplexan-like algae with a functional photosynthetic plastid that live in close association with corals potentially opens new opportunities for assisted evolution to take advantage of alternative sources of phototrophic energy. Alternative photosymbionts include Chromera velia, first isolated from the coral Plesiastrea versipora in Sydney Harbor and formally described as an apicomplexan-like alga in the Phylum Chromerida (Moore et al, 2008).…”

Babesia bovis: Actualidad del desarrollo de una vacuna

“…Las primeras formulaciones de vacunas fueron basadas en protozoos vivos que consistían en la inoculación de sangre infectada de un portador asintomático o que hubiera resuelto la infección a animales sanos, desencadenando una respuesta inmunológica que protegía parcialmente de la infección natural (51). Sin embargo, la necesidad de mantener gran cantidad de ganado bajo condiciones libres de garrapatas, el poco uso de animales donantes infectados, la gran antelación con que deben ser realizados los pedidos, los altos costos de producción y, sumado a esto, la dificultad para certificar su calidad, ha provocado que varios países hayan descontinuado la producción de este tipo de vacuna (19).…”

Proteínas importantes para la invasión de Babesia bovis a las células huésped

“…Una vez en su interior, los parásitos se reproducen por fisión binaria dando lugar a la formación de merozoítos con capacidad infectiva con lo cual se perpetua el crecimiento del parásito dentro del hospedero (8,9). El primer paso del proceso de invasión de merozoitos de Babesia a eritrocitos bovinos consiste en el reconocimiento inicial que se da gracias a la interacción entre proteínas de superficie de los merozoítos babesiales con las moléculas de superficie presentes en las células del hospedero (10,11). Posteriormente, el parásito se reorienta hacia su polo apical para disponer el contenido de las roptrias y micronemas y así establecer una unión móvil (UM) que facilita la invaginación de la membrana y la internalización del parásito dentro de la célula (12,13).…”