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1. Biomineral armor in leaf-cutter ants

   https://doi.org/10.1038/s41467-020-19566-3  

   Li, Hongjie; Sun, Chang-Yu; Fang, Yihang; Carlson, Caitlin M.; Xu, Huifang; Ješovnik, Ana; Sosa-Calvo, Jeffrey; Zarnowski, Robert; Bechtel, Hans A.; Fournelle, John H.; et al (December 2020, Nature Communications)

   null (Ed.)

   Abstract Although calcareous anatomical structures have evolved in diverse animal groups, such structures have been unknown in insects. Here, we report the discovery of high-magnesium calcite [CaMg(CO 3 ) 2 ] armor overlaying the exoskeletons of major workers of the leaf-cutter ant Acromyrmex echinatior . Live-rearing and in vitro synthesis experiments indicate that the biomineral layer accumulates rapidly as ant workers mature, that the layer is continuously distributed, covering nearly the entire integument, and that the ant epicuticle catalyzes biomineral nucleation and growth. In situ nanoindentation demonstrates that the biomineral layer significantly hardens the exoskeleton. Increased survival of ant workers with biomineralized exoskeletons during aggressive encounters with other ants and reduced infection by entomopathogenic fungi demonstrate the protective role of the biomineral layer. The discovery of biogenic high-magnesium calcite in the relatively well-studied leaf-cutting ants suggests that calcareous biominerals enriched in magnesium may be more common in metazoans than previously recognized. 

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2. Success of prophylactic antiviral therapy for SARS-CoV-2: Predicted critical efficacies and impact of different drug-specific mechanisms of action

   https://doi.org/10.1371/journal.pcbi.1008752  

   Czuppon, Peter; Débarre, Florence; Gonçalves, Antonio; Tenaillon, Olivier; Perelson, Alan S.; Guedj, Jérémie; Blanquart, François (March 2021, PLOS Computational Biology)

   Faeder, James R. (Ed.)

   Repurposed drugs that are safe and immediately available constitute a first line of defense against new viral infections. Despite limited antiviral activity against SARS-CoV-2, several drugs are being tested as medication or as prophylaxis to prevent infection. Using a stochastic model of early phase infection, we evaluate the success of prophylactic treatment with different drug types to prevent viral infection. We find that there exists a critical efficacy that a treatment must reach in order to block viral establishment. Treatment by a combination of drugs reduces the critical efficacy, most effectively by the combination of a drug blocking viral entry into cells and a drug increasing viral clearance. Below the critical efficacy, the risk of infection can nonetheless be reduced. Drugs blocking viral entry into cells or enhancing viral clearance reduce the risk of infection more than drugs that reduce viral production in infected cells. The larger the initial inoculum of infectious virus, the less likely is prevention of an infection. In our model, we find that as long as the viral inoculum is smaller than 10 infectious virus particles, viral infection can be prevented almost certainly with drugs of 90% efficacy (or more). Even when a viral infection cannot be prevented, antivirals delay the time to detectable viral loads. The largest delay of viral infection is achieved by drugs reducing viral production in infected cells. A delay of virus infection flattens the within-host viral dynamic curve, possibly reducing transmission and symptom severity. Thus, antiviral prophylaxis, even with reduced efficacy, could be efficiently used to prevent or alleviate infection in people at high risk. 

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3. The Effect of cytoskeleton inhibitors on coccolith morphology in Coccolithus braarudii and Scyphosphaera apsteinii

   https://doi.org/10.1111/jpy.13303  

   Langer, Gerald; Probert, Ian; Cox, Madison B.; Taylor, Alison; Harper, Glenn M.; Brownlee, Colin; Wheeler, Glen (December 2022, Journal of Phycology)

   The calcite platelets of coccolithophores (Haptophyta), the coccoliths, are among the most elaborate biomineral structures. How these unicellular algae accomplish the complex morphogenesis of coccoliths is still largely unknown. It has long been proposed that the cytoskeleton plays a central role in shaping the growing coccoliths. Previous studies have indicated that disruption of the microtubule network led to defects in coccolith morphogenesis inEmiliania huxleyiandCoccolithus braarudii. Disruption of the actin network also led to defects in coccolith morphology inE. huxleyi, but its impact on coccolith morphology inC. braarudiiwas unclear, as coccolith secretion was largely inhibited under the conditions used. A more detailed examination of the role of actin and microtubule networks is therefore required to address the wider role of the cytoskeleton in coccolith morphogenesis. In this study, we have examined coccolith morphology inC. braarudiiandScyphosphaera apsteiniifollowing treatment with the microtubule inhibitors vinblastine and colchicine (S. apsteiniionly) and the actin inhibitor cytochalasin B. We found that all cytoskeleton inhibitors induced coccolith malformations, strongly suggesting that both microtubules and actin filaments are instrumental in morphogenesis. By demonstrating the requirement for the microtubule and actin networks in coccolith morphogenesis in diverse species, our results suggest that both of these cytoskeletal elements are likely to play conserved roles in defining coccolith morphology. 

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4. Multiple infection of cells changes the dynamics of basic viral evolutionary processes

   https://doi.org/10.1002/evl3.95  

   Wodarz, Dominik; Levy, David_N; Komarova, Natalia_L (February 2019, Evolution Letters)

   Abstract The infection of cells by multiple copies of a given virus can impact viral evolution in a variety of ways, yet some of the most basic evolutionary dynamics remain underexplored. Using computational models, we investigate how infection multiplicity affects the fixation probability of mutants, the rate of mutant generation, and the timing of mutant invasion. An important insight from these models is that for neutral and disadvantageous phenotypes, rare mutants initially enjoy a fitness advantage in the presence of multiple infection of cells. This arises because multiple infection allows the rare mutant to enter more target cells and to spread faster, while it does not accelerate the spread of the resident wild-type virus. The rare mutant population can increase by entry into both uninfected and wild-type-infected cells, while the established wild-type population can initially only grow through entry into uninfected cells. Following this initial advantageous phase, the dynamics are governed by drift or negative selection, respectively, and a higher multiplicity reduces the chances that mutants fix in the population. Hence, while increased infection multiplicity promotes the presence of neutral and disadvantageous mutants in the short-term, it makes it less likely in the longer term. We show how these theoretical insights can be useful for the interpretation of experimental data on virus evolution at low and high multiplicities. The dynamics explored here provide a basis for the investigation of more complex viral evolutionary processes, including recombination, reassortment, as well as complementary/inhibitory interactions. 

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5. Jamaican fruit bats’ competence for Ebola but not Marburg virus is driven by intrinsic differences

   https://doi.org/10.1038/s41467-025-58305-4  

   van_Tol, Sarah; Port, Julia R; Fischer, Robert J; Gallogly, Shane; Bushmaker, Trenton; Griffin, Amanda; Schulz, Jonathan E; Carmody, Aaron; Myers, Lara; Crowley, Daniel E; et al (December 2025, Nature Communications)

   Abstract Ebola virus (EBOV) and Marburg virus (MARV) are zoonotic filoviruses that cause hemorrhagic fever in humans. Correlative data implicate bats as natural EBOV hosts, but neither a full-length genome nor an EBOV isolate has been found in any bats sampled. Here, we model filovirus infection in the Jamaican fruit bat (JFB),Artibeus jamaicensis,by inoculation with either EBOV or MARV through a combination of oral, intranasal, and subcutaneous routes. Infection with EBOV results in systemic virus replication and oral shedding of infectious virus. MARV replication is transient and does not shed. In vitro, JFB cells replicate EBOV more efficiently than MARV, and MARV infection induces innate antiviral responses that EBOV efficiently suppresses. Experiments using VSV pseudoparticles or replicating VSV expressing the EBOV or MARV glycoprotein demonstrate an advantage for EBOV entry and replication early, respectively, in JFB cells. Overall, this study describes filovirus species-specific phenotypes for both JFB and their cells. 

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