Biology subjects

Pacheco, Y.

Publications and source records attributed to Pacheco, Y..

3 recordsLinked to original sources

bioRxiv2025

SLAMF6 enables efficient attachment, synapse formation, and killing of HIV-1-infected CD4+ T cells by virus-specific CD8+ T cells

Efficient recognition and elimination of HIV-1-infected CD4+ T cells by cytotoxic CD8+ T cells (CTLs) require target cell engagement and the formation of a well-organized immunological synapse. Surface proteins belonging to the SLAM family are known to be crucial for stabilizing the immunological synapse and regulating antiviral responses during lymphotropic viral infections. In the context of HIV-1, there have been reports of SLAMF6 down-regulation in HIV-1-infected CD4+ T cells; however, the significance of this modulation for CTL function remains unclear. In this investigation, we used CTL lines from People living with HIV (PLWH) to examine the impact of SLAMF6 blockade on three pivotal processes: (1) the formation of CD8+-CD4+ T-cell conjugates, (2) the establishment of the immunological synapse, and (3) the killing and cytokine production capacity of HIV-1-specific CTLs during HIV-1 infection. Our findings reveal that the inability to form CD8+-CD4+ T-cell conjugates following incubation with an anti-SLAMF6 blocking antibody is primarily attributable to a defect in actin ring formation at the immunological synapse. Furthermore, SLAMF6 blockade leads to a reduction in the killing efficiency of HIV-1-infected CD4+ T cells by HIV-1-specific CTLs, underscoring the critical role of SLAMF6 in cytolytic function. This study highlights the importance of SLAMF6 receptors in modulating cytotoxic antiviral responses, shedding light on potential avenues for manipulation and enhancement of this pathway in the context of HIV and other lymphotropic viral infections.

immunology↗

bioRxiv2024

Antennal sensilla diversity in diurnal and nocturnal fireflies (Coleoptera, Lampyridae)

Insects use their antennae to collect environmental information. While the structural diversity of insect antennae is immediately obvious, the diversity of the minute antennal sensilla that interact with the environmental stimuli and translate them into sensory input, is largely unknown for many insect groups. This includes the beetle family Lampyridae, which includes nocturnal species that use bioluminescent signals during mate search, and diurnal species that rely exclusively on pheromones to identify and locate a potential mate. Diurnal species tend to have relatively larger antennae, and diurnal males have larger antennae than their females. It is generally assumed that antennal size reflects sensilla numbers, but this remains to be tested. Here we use Scanning Electron Microscopy to document the sensilla diversity of both males and females of three diurnal and four nocturnal firefly species, as well as total sensilla numbers, densities and their distribution along the antenna. We identified 14 sensilla morphotypes across the seven species, including 12 morphotypes that are new for Lampyridae. Mechanosensilla (3 morphotypes) were the most abundant and conserved sensilla across firefly species, and the distribution of chemosensilla (9 morphotypes) was unexpectedly variable across species. We hypothesized that the differences in mating signals between diurnal and nocturnal fireflies would be reflected in their chemosensilla counts or densities. As predicted, diurnal and nocturnal fireflies did not differ in their mechanoreceptor counts or densities, nor did males and females. In contrast, firefly males had significantly more chemoreceptors (and higher densities) than females and the interaction term (activity by sex) was also significant: diurnal males had significantly more chemoreceptors than nocturnal males, highlighting the importance of pheromones for diurnal species. Based on a series of predictions, we also identified a pheromone sensilla candidate for each species that will facilitate functional testing in future studies.

evolutionary biology↗

bioRxiv2021

Firefly bioluminescence outshines aerial predators

Bioluminescence is found across the tree of life and has many functions. Yet we understand very little about its timing and origins, particularly as a predator avoidance strategy. Understanding the timing between bioluminescence and predator origins has yet to be examined and can help elucidate the evolution of this ecologically important aposematic signal. Using the most prevalent bioluminescent group, fireflies, where bioluminescence primarily functions as aposematic and sexual signals, the timing for the origins of both potential predators of fireflies and bioluminescence is explored. Divergence time estimations were performed using genomic-scale phylogenetic reconstructions, and multiple fossil calibration points, allowing for a robust estimate for the origin of lampyrid bioluminescence as a terrestrial and as an aerial signal. Our results recover the origins of terrestrial beetle bioluminescence at 141.17 (122.63-161.17) mya and firefly aerial bioluminescence at 133.18 (117.86-152.47) mya with a large dataset focused on Lampyridae; and terrestrial bioluminescence as 148.03 (130.12-166.80) mya, with the age of aerial bioluminescence at 104.97 (99.00-120.90) mya with a complementary broad Elateroidea dataset. These ages predate the origins of all known extant aerial predators (i.e., bats and birds) and support the much older terrestrial predators (assassin bugs, frogs, ground beetles, lizards, snakes, hunting spiders, and harvestmen) as the most likely drivers of terrestrial bioluminescence in beetles, and sexual signaling likely being the original function in aerial fireflies.

evolutionary biology↗