Protist Diversity Responses to Experimental N Deposition in Biological Crusts of a Semiarid Mediterranean Ecosystem

Pérez-Uz, Blanca; Galfione, Virginia C.; Ochoa‐Hueso, Raúl; Martín‐Cereceda, Mercedes

doi:10.1016/j.protis.2022.125929

Cited by 2 publications

(1 citation statement)

References 93 publications

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“…Colpoda species share a common feature typical of all ciliates—the presence of a dimorphic nuclear apparatus, comprising both micronucleus and macronucleus sequestered in the same cytoplasm. To date, a total of 32 nominal species of Colpoda have been documented, and their cosmopolitan distribution has been empirically substantiated through an extensive body of global investigations ( 3 – 6 ). Moreover, they show highly similar life histories, characterized by distinct life stages, including trophonts—cells in a state of vegetative growth when food bacteria are abundant, reproductive cysts—a mode of asexual reproduction within a cyst wall that distinguishes them from most other ciliates ( 7 ), and resting cysts—a dormant stage that helps endure harsh and highly fluctuating soil environments ( 7 , 8 ).…”

Section: Introductionmentioning

confidence: 99%

Integrative analyses on the ciliates Colpoda illuminate the life history evolution of soil microorganisms

Li,

Wu,

Feng

et al. 2024

mSystems

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Microorganisms play a central role in sustaining soil ecosystems and agriculture, and these functions are usually associated with their complex life history. Yet, the regulation and evolution of life history have remained enigmatic and poorly understood, especially in protozoa, the third most abundant group of organisms in the soil. Here, we explore the life history of a cosmopolitan species— Colpoda steinii . Our analysis has yielded a high-quality macronuclear genome for C. steinii , with size of 155 Mbp and 37,123 protein-coding genes, as well as mean intron length of ~93 bp, longer than most other studied ciliates. Notably, we identify two possible whole-genome duplication events in C. steinii , which may account for its genome being about twice the size of C. inflata’s , another co-existing species. We further resolve the gene expression profiles in diverse life stages of C. steinii , which are also corroborated in C. inflata . During the resting cyst stage, genes associated with cell death and vacuole formation are upregulated, and translation-related genes are downregulated. While the translation-related genes are upregulated during the excystment of resting cysts. Reproductive cysts exhibit a significant reduction in cell adhesion. We also demonstrate that most genes expressed in specific life stages are under strong purifying selection. This study offers a deeper understanding of the life history evolution that underpins the extraordinary success and ecological functions of microorganisms in soil ecosystems. IMPORTANCE Colpoda species, as a prominent group among the most widely distributed and abundant soil microorganisms, play a crucial role in sustaining soil ecosystems and promoting plant growth. This investigation reveals their exceptional macronuclear genomic features, including significantly large genome size, long introns, and numerous gene duplications. The gene expression profiles and the specific biological functions associated with the transitions between various life stages are also elucidated. The vast majority of genes linked to life stage transitions are subject to strong purifying selection, as inferred from multiple natural strains newly isolated and deeply sequenced. This substantiates the enduring and conservative nature of Colpoda ’s life history, which has persisted throughout the extensive evolutionary history of these highly successful protozoa in soil. These findings shed light on the evolutionary dynamics of microbial eukaryotes in the ever-fluctuating soil environments. This integrative research represents a significant advancement in understanding the life histories of these understudied single-celled eukaryotes.

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