Biology subjects

Ortiz, G.

Publications and source records attributed to Ortiz, G..

7 recordsLinked to original sources

bioRxiv2026

Coated Bacterial Vaccine Platform Overcomes Weak Antigen Immunogenicity: A Functional Approach to GnRH-Based Immunocastration

Immunocastration, a non-surgical strategy based on active immunization against gonadotropin-releasing hormone (GnRH), effectively suppresses steroidogenesis and spermatogenesis. However, peptide vaccines targeting poorly immunogenic antigens such as GnRH often fail to elicit robust adaptive immune responses, requiring adjuvants or carrier proteins. Previously, we introduced Coated Bacterial Vaccines (CBVs), a platform that uses chemically inactivated Gram-positive bacteria to display recombinant antigens fused to the SlpA carboxy-terminal domain (dSLPA) on their surface. This system leverages natural pathogen-associated molecular patterns (PAMPs) to enhance immunogenicity without additional adjuvants. In this work, we extended the application of the CBVs platform to enhance the immune response against a poorly immunogenic GnRH-based peptide vaccine. GnRH-CBVs were formulated using inactivated Bacillus subtilis var. natto coated with a recombinant GnRH tandem-repeat-dSLPA fusion protein and administered to male BALB/c mice. A chitosan-adjuvanted GnRH-dSLPA formulation served as a positive control. GnRH-CBVs induced a strong Th2-biased humoral response, characterized by predominant IgG1 levels comparable to those achieved with chitosan. The resulting antibodies effectively neutralized endogenous GnRH, reducing steroidogenesis and spermatogenesis and inducing marked testicular histological alterations. These findings support CBVs as a promising strategy to enhance peptide vaccine immunogenicity for veterinary immunocastration.

immunology↗

bioRxiv2026

Mechanobiological Specialization of Choroid Plexus Macrophages Defined by Titin Expression

Functioning both as the site of cerebrospinal fluid production and as an interface between the peripheral circulation and the central nervous system, the choroid plexus (ChP) modulates the gating of immune cells and signals from the periphery as they pass from the blood into cerebrospinal fluid. We generated a single-nucleus and spatial transcriptomic atlas of the adult human ChP, in donors with and without Alzheimers disease (AD), revealing transcriptionally and spatially distinct macrophage states. We identified a previously unrecognized population of titin-expressing (TTN+) tissue-resident macrophages characterized by coordinated activation of cytoskeletal remodeling, phagocytosis, autophagy, and inflammatory programs. Isoform-specific qPCR, protein immunofluorescence, and single-molecule FISH validated TTN expression in situ. In AD, TTN+ macrophages expand and undergo broad transcriptional rewiring, including activation of MEF2-linked mechanotransduction pathways, elevated senescence signatures, and a loss of ligand-receptor connectivity with epithelial, endothelial, and stromal partners. Collectively, our findings define a mechanosensitive macrophage program at the blood-CSF interface and uncover a TTN-associated shift in macrophage function and microenvironment integration in AD.

neuroscience↗

bioRxiv2023

A red-emitting carborhodamine for monitoring and measuring membrane potential

Biological membrane potentials, or voltages, are a central facet of cellular life. Optical methods to visualize cellular membrane voltages with fluorescent indicators are an attractive complement to traditional electrode-based approaches, since imaging methods can be high throughput, less invasive, and provide more spatial resolution than electrodes. Recently developed fluorescent indicators for voltage largely report changes in membrane voltage by monitoring voltage-dependent fluctuations in fluorescence intensity. However, it would be useful to be able to not only monitor changes, but also measure values of membrane potentials. This study discloses a new fluorescent indicator which can address both. We describe the synthesis of a new sulfonated tetramethyl carborhodamine fluorophore. When this carborhodamine is conjugated with an electron-rich, methoxy (-OMe) containing phenylenevinylene molecular wire, the resulting molecule, CRhOMe, is a voltage-sensitive fluorophore with red/far-red fluorescence. Using CRhOMe, changes in cellular membrane potential can be read out using fluorescence intensity or lifetime. In fluorescence intensity mode, CRhOMe tracks fast-spiking neuronal action potentials with greater signal-to-noise than state-of-the-art BeRST (another voltage-sensitive fluorophore). CRhOMe can also measure values of membrane potential. The fluorescence lifetime of CRhOMe follows a single exponential decay, substantially improving the quantification of membrane potential values using fluorescence lifetime imaging microscopy (FLIM). The combination of red-shifted excitation and emission, mono-exponential decay, and high voltage sensitivity enable fast FLIM recording of action potentials in cardiomyocytes. The ability to both monitor and measure membrane potentials with red light using CRhOMe makes it an important approach for studying biological voltages. Significance StatementBiological membrane potentials are maintained by all forms of life. In electrically excitable cells, fast changes in membrane potential drive downstream events: neurotransmitter release, contraction, or insulin secretion. The ability to monitor changes in and measure values of cellular membrane potentials is central to a mechanistic understanding of cellular physiology and disease. Traditional modes for measuring membrane potential use electrodes, which are invasive, destructive, low throughput, and ill-suited to interrogate spatial dynamics of membrane potentials. Optical methods to visualize potentials with fluorescent dyes offer a powerful complement to traditional electrode approaches. In this study, we show that a new, red to farred fluorophore can both monitor changes in and measure values of membrane potential in a variety of living systems.

physiology↗

bioRxiv2022

Topological action potentials in engineered tissues

Due to the nonlinear current-voltage relations of ion channels, an interface between two tissues can have very different bioelectrical properties compared to either tissue on its own. Here we show experimentally that gap junction-coupled interfaces between non-excitable tissues can be electrically excitable. This topologically protected excitability occurs over a far larger range of ion channel expression levels than does excitability in the bulk. Topological excitations at tissue interfaces can cause local elevations in calcium concentration, possibly providing a bioelectrical mechanism for interface sensing. As in condensed matter physics, topological excitations in electrophysiology constitute a distinct class of phenomena which may show exotic and novel properties.

biophysics↗

bioRxiv2019

Feasibility analysis of semiconductor voltage nanosensors for neuronal membrane potential sensing

In the last decade, optical imaging methods have significantly improved our understanding of the information processing principles in the brain. Although many promising tools have been designed, sensors of membrane potential are lagging behind the rest. Semiconductor nanoparticles are an attractive alternative to classical voltage indicators, such as voltage-sensitive dyes and proteins. Such nanoparticles exhibit high sensitivity to external electric fields via the quantum-confined Stark effect. Here we report the development of lipid-coated semiconductor voltage-sensitive nanorods (vsNRs) that self-insert into the neuronal membrane. We describe a workflow to detect and process the photoluminescent signal of vsNRs after wide-field time-lapse recordings. We also present data indicating that vsNRs are feasible for sensing membrane potential in neurons at a single-particle level. This shows the potential of vsNRs for detection of neuronal activity with unprecedentedly high spatial and temporal resolution.

bioengineering↗

bioRxiv2019

Bioelectrical signaling via domain wall migration

AbstractElectrical signaling in biology is typically associated with action potentials, transient spikes in membrane voltage that return to baseline. The Hodgkin-Huxley equations of electrophysiology belong to a more general class of reaction-diffusion equations which could, in principle, support patterns of membrane voltage which are stable in time but structured in space. Here we show theoretically and experimentally that homogeneous or nearly homogeneous tissues can undergo spontaneous spatial symmetry breaking into domains with different resting potentials, separated by stable bioelectrical domain walls. Transitions from one resting potential to another can occur through long-range migration of these domain walls. We map bioelectrical domain wall motion using all-optical electrophysiology in an engineered stable cell line and in human iPSC-derived myoblasts. Bioelectrical domain wall migration may occur during embryonic development and during physiological signaling processes in polarized tissues. These results demonstrate a novel form of bioelectrical pattern formation and long-range signaling.

biophysics↗

bioRxiv2018

Multimodal on-axis platform for all-optical electrophysiology with near-infrared probes in human stem-cell-derived cardiomyocytes

Combined optogenetic stimulation and optical imaging permits scalable, high-throughput probing of cellular electrophysiology and optimization of stem-cell derived excitable cells, such as neurons and muscle cells. We report a new \"on-axis\" configuration of OptoDyCE, our all-optical platform for studying human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) and other cell types, optically driven by Channelrhodopsin2 (ChR2). This solid-state system integrates optogenetic stimulation with temporally-multiplexed simultaneous recording of membrane voltage (Vm) and intracellular calcium ([Ca2+]i) dynamics using a single photodetector. We demonstrate the capacity for combining multiple spectrally-compatible actuators and sensors, including newer high-performance near-infrared (NIR) voltage probes BeRST1 and Di-4-ANBDQBS, to record complex spatiotemporal responses of hiPSC-CMs to drugs in a high-throughput manner.

bioengineering↗