Biology subjects

del Arco, A.

Publications and source records attributed to del Arco, A..

4 recordsLinked to original sources

bioRxiv2024

Virophage replication mode determines ecological and evolutionary changes in a host-virus-virophage system

Giant viruses can control their eukaryotic host populations, shaping the ecology and evolution of aquatic microbial communities. Understanding the impact of the viruses own parasites, the virophages, on their control of microbial communities remains a challenge. Most virophages have two modes of host infection and replication. They can exist as free particles that co-infect a host cell with the virus and replicate but inhibit viral replication. Virophages can also integrate into the host genome and remain dormant until the host is infected with a virus, leading to virophage reactivation and replication that does not immediately inhibit viral replication. Both replication modes are present within host-virus-virophage communities, and their relative contributions are expected to be context dependent and dynamic over time. The consequences of this dynamic regime for ecological and evolutionary dynamics remain unexplored. Here, we test whether and how the relative contribution of virophage replication modes influences the ecological dynamics of an experimental host-virus-virophage system and the evolutionary responses of the virophage. To do this, we indirectly manipulated the level of virophage (Mavirus) integration into the host (Cafeteria burkhardae) in the presence of the giant Cafeteria roenbergensis virus (CroV) (later identified as Cafeteria burkhardae, Schoenle et al. 2020). Our results show that higher virophage integration is positively correlated with host survival, but negatively correlated with virophage reactivation. In addition, communities with higher virophage integration were characterised by lower population densities and reduced fluctuations in both host and viral populations, whereas virophage fluctuations were increased. This study reveals the complex interplay between virophages, viruses and hosts, in which the virophage dual replication mode is a dynamic and reactive mechanism contributing to persistence of the microbial community.

evolutionary biology↗

bioRxiv2023

Population dynamics hide phenotypic changes driven by subtle chemical exposures: implications for risk assessments

Ecological risk assessment of chemicals focuses on the response of different taxa in isolation not taking ecological and evolutionary interplay in communities into account. Its consideration would, however, allow for an improved assessment by testing for implications within and across trophic levels and changes in the phenotypic and genotypic diversity within populations. We present a simple experimental system that can be used to evaluate the ecological and evolutionary responses to chemical exposure at microbial community levels. We exposed a microbial model system of the ciliate Tetrahymena thermophila (predator) and the bacterium Pseudomonas fluorescens (prey) to iron released from Magnetic Particles (MP-Fedis), which are Phosphorus (P) adsorbents used in lake restoration. Our results show that while the responses of predator single population size differed across concentrations of MP-Fedis and the responses of prey from communities differed also across concentration of MP-Fedis, the community responses (species ratio) were similar for the different MP-Fedis concentrations. Looking further at an evolutionary change in the bacterial preys defence, we found that MP-Fedis drove different patterns and dynamics of defence evolution. Overall, our study shows how similar community dynamics mask changes at evolutionary levels what would be overlooked in the design of current risk assessment protocols where evolutionary approaches are not considered.

evolutionary biology↗

bioRxiv2023

Evolution of virus and virophage facilitates persistence in a tripartite microbial system

Tripartite biotic interactions are inherently complex, and the strong interdependence of species and high levels of exploitation can make these systems short-lived and vulnerable to extinction. The persistence of species depends then on the balance between exploitation and avoidance of exploitation of the resource beyond the point where sustainable exploitation is no longer possible. We used this general prediction to test the potential for long-term persistence in a recently discovered tripartite microbial system in which a eukaryotic host is preyed upon by a giant virus that is in turn parasitized by a virophage. Host and virophage may benefit from this interaction because the virophage reduces the harmful effects of the giant virus on the host population over time and the virophage can survive integrated into the host genome when giant viruses are scarce. Here, we grew hosts in the presence and absence of the giant virus and virophage over ~280 host generations. We found that the three players persisted, but that the beneficial effect of the virophage for the host population diminished over time. We further tested whether the level of exploitation and replication evolved in the giant virus and/or virophage population over the course of the experiment and whether the changes were such that they avoid overexploitation. We found that the giant virus evolved towards lower replication levels and the virophage towards increased replication but decreased giant virus exploitation. These changes are predicted to facilitate persistence by lowering giant virus and host exploitation and consequently reducing the protective effect of the virophage.

evolutionary biology↗

bioRxiv2021

A feed-forward Ca2+-dependent mechanism boosting glycolysis and OXPHOS by activating Aralar-malate-aspartate shuttle, upon neuronal stimulation

Calcium is an important second messenger regulating a bioenergetic response to the workloads triggered by neuronal activation. In cortical neurons using glucose as only fuel, activation by NMDA, which elicits a strong workload dependent on Na+ entry, stimulates glucose uptake, glycolysis, pyruvate and lactate production, and OXPHOS in a Ca2+-dependent way. We find that Ca2+-upregulation of glycolysis, pyruvate levels and respiration, but not glucose uptake, all depend on Aralar/AGC1/Slc25a12, the Ca2+regulated mitochondrial aspartate-glutamate carrier, component of the malate-aspartate shuttle (MAS). Ca2+-activation of MAS increases pyruvate production, which directly fuels workload-stimulated respiration. Also it stimulates glycolysis. MCU silencing had no effect indicating that none of these processes required mitochondrial Ca2+. The neuronal respiratory response to carbachol was also dependent on Aralar, but not on MCU. We also find that cortical neurons are endowed with a constitutive ER-to-mitochondria Ca2+ flow maintaining basal cell bioenergetics in which Ryanodine receptors, RyR2, rather than InsP3R, are responsible for Ca2+ release, and in which MCU does not participate. The results reveal that in neurons using glucose MCU does not participate in OXPHOS regulation under basal or stimulated conditions, while Aralar-MAS appears as the major Ca2+-dependent pathway tuning simultaneously glycolysis and OXPHOS to neuronal activation.

neuroscience↗