Biology subjects

Hernandez, A.

Publications and source records attributed to Hernandez, A..

6 recordsLinked to original sources

bioRxiv2021

Integrated Regulation of PKA by Fast and Slow Neurotransmission in the Nucleus Accumbens Controls Plasticity and Stress Responses

Cortical glutamate and midbrain dopamine neurotransmission converge to mediate striatum-dependent behaviors, while maladaptations in striatal circuitry contribute to mental disorders. Here we uncover a molecular mechanism by which glutamatergic and dopaminergic signaling integrate to regulate cAMP-dependent protein kinase (PKA) via phosphorylation of the PKA regulatory subunit, RII{beta}. We find that glutamate-dependent reduction in Cdk5-dependent RII{beta} phosphorylation alters the PKA holoenzyme auto-inhibitory state to increase PKA signaling in response to dopamine. Disruption of RII{beta} phosphorylation by Cdk5, consequently, enhances cortico-ventral striatal synaptic plasticity. Acute and chronic stress in rats inversely modulate RII{beta} phosphorylation and ventral striatal infusion of a small interfering peptide that selectively targets RII{beta} regulation by Cdk5 improves behavioral response to stress. This new signaling mechanism integrating ventral striatal glutamate and dopamine neurotransmission is likely important to brain function, may contribute to neuropsychiatric conditions, and serves as a possible target for the development of novel therapeutics for stress-related disorders.

neuroscience↗

bioRxiv2021

Relationship between bacterial phylotype and specialized metabolite production in the culturable microbiome of two freshwater sponges

Microbial drug discovery programs rely heavily on accessing bacterial diversity from the environment to acquire new specialized metabolite (SM) lead compounds for the therapeutic pipeline. Therefore, knowledge of how certain bacterial taxa are distributed in nature, in addition to the degree of variation of SM production within those taxa, is critical to informing these front-end discovery efforts and making the overall sample collection and bacterial library creation process more efficient. In the current study we employed MALDI-TOF mass spectrometry and the bioinformatics pipeline IDBac to analyze diversity within phylotype groupings and SM profiles of hundreds of bacterial isolates from two Eunapius fragilis freshwater sponges, collected 1.5 km apart. We demonstrated that within two sponge samples of the same species, the culturable bacterial populations contained significant overlap in approximate genus-level phylotypes but mostly non-overlapping populations of isolates when grouped lower than the level of genus. Further, correlations between bacterial phylotype and SM production varied at the species level and below, suggesting SM distribution within bacterial taxa must be analyzed on a case-by-case basis. Our results suggest that two E. fragilis freshwater sponges collected in similar environments can exhibit large culturable diversity on a species-level scale, thus researchers should scrutinize the isolates with analyses that take both phylogeny and SM production into account in order to optimize the chemical space entering into a downstream bacterial library.

microbiology↗

bioRxiv2021

High efficacy of therapeutic equine hyperimmune antibodies against SARS CoV-2 variants of concern

SARS-CoV-2 variants of concern (VoC) show reduced neutralization by vaccine-induced and therapeutic monoclonal antibodies. We tested therapeutic equine polyclonal antibodies (pAbs) against four VoC (alpha, beta, epsilon and gamma). We show that equine pAbs efficiently neutralize VoC, suggesting they are an effective, broad coverage, low-cost and a scalable COVID-19 treatment.

microbiology↗

bioRxiv2021

Cytoskeleton-extracellular matrix interaction is required to maintain mitochondrial Ca2+ control in mouse skeletal muscle fibre

Cells rapidly lose their physiological phenotype upon disruption of their extracellular matrix (ECM)-intracellular cytoskeleton interactions. Here, we investigated acute effects of ECM disruption on cellular and mitochondrial morphology, transcriptomic signatures, and Ca2+ handling in adult mouse skeletal muscle fibers. Adult skeletal muscle fibers were isolated from mouse toe muscle either by collagenase-induced dissociation of the ECM or by mechanical dissection that leaves the contiguous ECM intact. Experiments were generally performed four hours after cell isolation. At this time, there were striking differences in the gene expression patterns between fibers isolated with the two methods; 24h after cell isolation, enzymatically dissociated fibers had transcriptomic signatures resembling dystrophic phenotypes. Mitochondrial appearance was grossly similar in the two groups, but 3D electron microscopy revealed shorter and less branched mitochondria in enzymatically dissociated than in mechanically dissected fibers. Similar increases in free cytosolic [Ca2+] during repeated tetanic stimulation were accompanied by marked mitochondrial Ca2+ uptake only in enzymatically dissociated muscle fibers. The aberrant mitochondrial Ca2+ uptake was partially prevented by the mitochondrial Ca2+ uniporter inhibitor Ru360 and by cyclosporine A and NV556, which inhibit the mitochondrial protein Ppif (also called cyclophilin D). Importantly, inhibition of Ppif with NV556 significantly improved survival of mice with mitochondrial myopathy in which muscle mitochondria take up excessive amounts of Ca2+ even with an intact ECM. In conclusion, skeletal muscle fibers isolated by collagenase-induced dissociation of the ECM display aberrant mitochondrial Ca2+ uptake, which involves a Ppif-dependent mitochondrial Ca2+ influx resembling that observed in mitochondrial myopathies.

physiology↗

bioRxiv2020

Development and pre-clinical characterization of two therapeutic equine formulations towards SARS-CoV-2 proteins for the potential treatment of COVID-19

In the current global emergency due to SARS-CoV-2 outbreak, passive immunotherapy emerges as a promising treatment for COVID-19. Among animal-derived products, equine formulations are still the cornerstone therapy for treating envenomations due to animal bites and stings. Therefore, drawing upon decades of experience in manufacturing snake antivenom, we developed and preclinically evaluated two anti-SARS-CoV-2 polyclonal equine formulations as potential alternative therapy for COVID-19. We immunized two groups of horses with either S1 (anti-S1) or a mixture of S1, N, and SEM mosaic (anti-Mix) viral recombinant proteins. Horses reached a maximum anti-viral antibody level at 7 weeks following priming, and showed no major adverse acute or chronic clinical alterations. Two whole-IgG formulations were prepared via hyperimmune plasma precipitation with caprylic acid and then formulated for parenteral use. Both preparations had similar physicochemical and microbiological quality and showed ELISA immunoreactivity towards S1 protein and the receptor binding domain (RBD). The anti-Mix formulation also presented immunoreactivity against N protein. Due to high anti-S1 and anti-RBD antibody content, final products exhibited high in vitro neutralizing capacity of SARS-CoV-2 infection, 80 times higher than a pool of human convalescent plasma. Pre-clinical quality profiles were similar among both products, but clinical efficacy and safety must be tested in clinical trials. The technological strategy we describe here can be adapted by other producers, particularly in low- and middle-income countries.

microbiology↗

bioRxiv2020

Does participation in acoustic experiments provide enrichment to animals under human care? A case study of three grey seals (Halichoerus grypus)

Both mental and physiological conditions determine the well-being state in an animal. Enrichment is a way to increase an animals well-being and may require problem solving through thinking, tolerance of ambiguity, openness, and intrinsic motivation. It is unclear if it is enriching when an animal participates in different types of research. Therefore, it is important to answer the question of whether research can be used as an enrichment tool in zoological facilities. Here, we examine if participation in psychophysical research affected the mental stimulation of three grey seals under human care. The effects varied amongst the three individuals that took part in the research, and indicated that their participation in the research task was dependent on their individual personalities and life history. Two seals indicated that their involvement in the research was positive and motivating, and therefore can be considered enriching. In comparison, the third seal displayed a tendency for frustration and low motivation. Our results indicate that research can be a powerful enrichment tool with animals that find research motivating.

animal behavior and cognition↗