Biology subjects

Flores, J. A.

Publications and source records attributed to Flores, J. A..

3 recordsLinked to original sources

bioRxiv2025

Diversity and composition of microbial communities in shrimp ponds sediments: A metagenomic approach

The cultivation of Litopenaeus vannamei is of great economic importance to Ecuador, yet it faces significant challenges due to microbial diseases. This study analyzes the microbial metagenome in white shrimp culture ponds sediments, assessing the diversity and communities of both pathogenic and non-pathogenic bacteria. Sediment samples were collected from ponds in three provinces with varying salinity levels: province of Guayas (6.28 g/L), El Oro (21 g/L), and Santa Elena (48 g/L). Through sequencing the V3-V4 region of the 16S rRNA gene, diverse microbial communities were identified, significantly influenced by salinity. Results revealed that microbial communities vary among locations, highlighting the presence of pathogenic bacteria such as Proteobacteria and beneficial ones like Firmicutes. Shannon and Simpson indices indicated high diversity and evenness in Guayas, El Oro, and Santa Elena (Shannon: 5.547, 5.810, and 4.326; Simpson: 0.9953, 0.9957, and 0.982, respectively). This analysis provides crucial information for improving management and sustainability of shrimp aquaculture, offering insights into the complex microbial ecosystems in culture environments and their potential impact on shrimp health and production.

genomics↗

bioRxiv2025

Calcium induced N-terminal gating and pore collapse in connexin-46/50 gap junctions

Gap junctions facilitate electrical and metabolic coupling essential for tissue function. Under ischemic conditions (e.g., heart attack or stroke), elevated intracellular calcium (Ca2+) levels uncouple these cell-to-cell communication pathways to protect healthy cells from cytotoxic signals. Using single-particle cryo-EM, we elucidate details of the Ca2+-induced gating mechanism of native connexin-46/50 (Cx46/50) gap junctions. The resolved structures reveal Ca2+ binding sites within the channel pore that alter the chemical environment of the permeation pathway and induce diverse occluded and gated states through N-terminal domain remodeling. Moreover, subunit rearrangements lead to pore collapse, enabling steric blockade by the N-terminal domains, reminiscent of the "iris model" of gating proposed over four decades ago. These findings unify and expand key elements of previous gating models, providing mechanistic insights into how Ca2+ signaling regulates gap junction uncoupling and broader implications for understanding cell stress responses and tissue protection.

biophysics↗

bioRxiv2020

Connexin-46/50 in a dynamic lipid environment resolved by CryoEM at 1.9 A

Gap junctions establish direct pathways for connected cells and tissues to transfer metabolic and electrical messages1. The local lipid environment is known to affect the structure, stability and intercellular channel activity of gap junctions2-5; however, the molecular basis for these effects remains unknown. To gain insight toward how gap junctions interact with their local membrane environment, we used lipid nanodisc technology to incorporate native connexin-46/50 (Cx46/50) intercellular channels into a dual lipid membrane system, closely mimicking a native cell-to-cell junction. Structural characterization of Cx46/50 lipid-embedded channels by single particle CryoEM revealed a lipid-induced stabilization to the channel, resulting in a 3D reconstruction at 1.9 [A] resolution. Together with all-atom molecular dynamics (MD) simulations and 3D heterogeneity analysis of the ensemble CryoEM data, it is shown that Cx46/50 in turn imparts long-range stabilization to the dynamic local lipid environment that is specific to the extracellular lipid leaflet of the two opposed membranes. In addition, nearly 400 water molecules are resolved in the CryoEM map, localized throughout the intercellular permeation pathway and contributing to the channel architecture. These results illustrate how the aqueous-lipid environment is integrated with the architectural stability, structure and function of gap junction communication channels, and demonstrates the ability of CryoEM to effectively characterize dynamical protein-lipid interactions.

biophysics↗