Biology subjects

Valadez-Ingersoll, M.

Publications and source records attributed to Valadez-Ingersoll, M..

3 recordsLinked to original sources

bioRxiv2025

Symbiotic State Affects Microbiome Recovery in a Facultatively Symbiotic Cnidarian

The cnidarian holobiont consists of host cells, algal symbionts, and a complex microbiome that resides in and on the host tissue and the algal symbionts. To investigate the interactions between a host cnidarian, its algal symbionts, and its bacterial microbiome, we used antibiotics to deplete the microbiome of the facultatively symbiotic sea anemone Exaiptasia pallida (Aiptasia) in both symbiotic and aposymbiotic states. To understand the dynamics of microbiome reestablishment following disruption, we used 16S gene sequencing of the bacterial microbiome to characterize communities during recovery following antibiotic treatment. We assessed the host molecular response to microbiome depletion and recovery using RNA-seq and Western blotting of the immune transcription factor NF-{kappa}B. 16S results demonstrate that, following depletion, symbiotic Aiptasia can reestablish bacterial communities (based on diversity metrics and community composition) alike to those of controls before microbiome depletion. However, the microbiomes of aposymbiotic Aiptasia fail to reestablish to control conditions even after seven days of recovery. Bacteria in the Family Endozoicomonadaceae reestablish to control levels in symbiotic, but not aposymbiotic, Aiptasia, suggesting an association between Endozoicomonadaceae and algal symbionts. Our molecular analyses show that host immune system gene expression is downregulated during recovery from antibiotic treatment, but that NF-{kappa}B protein levels increase during recovery, suggesting mechanisms for microbiome reestablishment following disruption. This study shows the dynamics of microbiome recovery following depletion and the influence of microbiome community members on host gene expression in a cnidarian model, providing a foundation for future research involving pairwise interactions between microorganisms and cnidarian hosts.

microbiology↗

bioRxiv2024

Single-cell RNA-sequencing reveals immune system compartmentalization under symbiosis in the stony coral Oculina arbuscula

Many cnidarians host single-celled algae within gastrodermal cells, yielding a mutually beneficial exchange of nutrients between host and symbiont, and dysbiosis can lead to host mortality. Previous research has uncovered symbiosis tradeoffs, including suppression of immune pathways in cnidarians hosting intracellular algae and correlations between symbiotic state and pathogen susceptibility. Here, we used a multiomic approach to characterize symbiotic states of the facultatively symbiotic coral Oculina arbuscula by generating genotype-controlled fragments of symbiotic and aposymbiotic tissue. 16S metabarcoding showed no difference in bacterial communities between symbiotic states. Whole-organism proteomics revealed differential abundance of proteins related to immunity, confirming immune suppression during symbiosis. Finally, single-cell RNAseq identified diverse cell clusters within seven cell types across symbiotic states. Specifically, the gastrodermal cell clusters containing algal-hosting cells from symbiotic tissue had higher expression of nitrogen cycling and sugar transport genes than aposymbiotic gastrodermal cells. Furthermore, differential enrichment of immune system gene pathways and lower expression of genes involved in immune regulation were observed in these gastrodermal cells from symbiotic tissue. However, no differences in immune gene expression in the immune cell cluster were observed between symbiotic states. This work reveals a compartmentalization of immune system regulation in specific gastrodermal cells in symbiosis, which may limit symbiosis tradeoffs by simultaneously dampening immunity in algal-hosting cells while maintaining general organismal immunity.

genomics↗

bioRxiv2023

Nutrient deprivation differentially affects gene expression, immunity, and pathogen susceptibility across symbiotic states in a model cnidarian

Mutualistic symbioses between cnidarians and photosynthetic algae are modulated by complex interactions between host immunity and environmental conditions. Here, we investigate how symbiosis interacts with nutrient limitation to influence gene expression and stress response programming in the sea anemone Exaiptasia pallida (Aiptasia). Transcriptomic responses to starvation were similar between symbiotic and aposymbiotic Aiptasia; however, aposymbiotic anemone responses were stronger. Starved Aiptasia of both symbiotic states exhibited increased protein levels of immune-related transcription factor NF-{kappa}B, its associated gene pathways, and putative target genes. However, this starvation-induced increase in NF-{kappa}B only correlated with increased immunity in symbiotic anemones. Furthermore, starvation had opposite effects on Aiptasia susceptibility to pathogen and oxidative stress challenges, suggesting distinct energetic priorities under nutrient scarce conditions. Finally, when we compared starvation responses in Aiptasia to those of a facultative coral and nonsymbiotic anemone, "defense" responses were similarly regulated in Aiptasia and the facultative coral, but not in the nonsymbiotic anemone. This pattern suggests that capacity for symbiosis influences immune responses in cnidarians. In summary, expression of certain immune pathways - including NF-{kappa}B - does not necessarily predict susceptibility to pathogens, highlighting the complexities of cnidarian immunity and the influence of symbiosis under varying energetic demands.

genomics↗