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Many insects engage in symbiotic associations with diverse assemblages of bacterial symbionts that can deeply impact on their ecology and evolution. The intraspecific variation of symbionts remains poorly assessed while phenotypic effects and transmission behaviors, which are key processes for the persistence and evolution of symbioses, may differ widely depending on the symbiont strains. Serratia symbiotica is one of the most frequent symbiont species in aphids and a valuable model to assess this intraspecific variation since it includes both facultative and obligate symbiotic strains. Despite evidence that some facultative S. symbiotica strains exhibit a free-living capacity, the presence of these strains in wild aphid populations, as well as in insects with which they maintain regular contact, has never been demonstrated. Here, we examined the prevalence, diversity, and tissue tropism of S. symbiotica in wild aphids and associated ants. We found a high occurrence of S. symbiotica infection in ant populations, especially when having tended infected aphid colonies. We also found that the S. symbiotica diversity includes strains found located within the gut of aphids and ants. In the latter, this tissue tropism was found restricted to the proventriculus. Altogether, these findings highlight the extraordinary diversity and versatility of an insect symbiont and suggest the existence of novel routes for symbiont acquisition in insects.

The human voltage‐gated sodium channel Nav1.5 (hNav1.5/SCN5A) plays a critical role in the initiation and propagation of action potentials in cardiac myocytes, and its modulation by various drugs has significant implications for cardiac safety. Drug‐dependent block of Nav1.5 current (INa) can lead to significant alterations in cardiac electrophysiology, potentially resulting in conduction slowing and an increased risk of proarrhythmic events. This review aims to provide a comprehensive overview of the mechanisms by which various pharmacological agents interact with Nav1.5, focusing on the molecular determinants of drug binding and the resultant electrophysiological effects. We discuss the structural features of Nav1.5 that influence drug affinity and specificity. Special attention is given to the concept of state‐dependent block, where drug binding is influenced by the conformational state of the channel, and its relevance to therapeutic efficacy and safety. The review also examines the clinical implications of INa block, highlighting case studies of drugs that have been associated with adverse cardiac events, and how the Vaughan‐Williams Classification system has been employed to qualify “unsafe” sodium channel block. Furthermore, we explore the methodologies currently used to assess INa block in nonclinical and clinical settings, with the hope of providing a weight of evidence approach including in silico modeling, in vitro electrophysiological assays and in vivo cardiac safety studies for mitigating proarrhythmic risk early in drug discovery. This review underscores the importance of understanding Nav1.5 pharmacology in the context of drug development and cardiac risk assessment.

Order versus disorder in the structure of materials plays a key role in the theoretical prediction of their properties. However, this structural description appears to be ineffective for new families of materials such as high entropy alloys (HEAs), which combine crystallographic order with chemical disorder. Here, we demonstrate for five-element HEAs as pure solid solutions that the chemical disorder of the elements decorating their cubic structure underlies the generation of second optical harmonics, overcoming the theoretical limit imposed on centrosymmetric crystals. Moreover, we discover that this disorder, inherent to HEAs, sets a threshold for non-linear light emission from the 4th to the 26th order. As a consequence of the 0.5 eV broadening of the energy levels of the five elements of the HEA, the emission spectrum covers broad visible (400-650 nm) and infrared (800-1600 nm) ranges. In addition to the challenge of theoretically predicting non-linear effects in unconventional materials, the duality of structural order and chemical disorder in HEAs offers the opportunity to design sustainable alternatives to urgently needed optical materials.