Biology subjects

Sosa, E.

Publications and source records attributed to Sosa, E..

8 recordsLinked to original sources

bioRxiv2025

Different kinetics of humoral response against individual antigens in the ovine model of Toxoplasma gondii infection and its pathological association

BackgroundToxoplasma gondii is a globally distributed protozoan parasite with major implications for human and animal health. In sheep, infection can cause reproductive failure and represents an important source of zoonotic transmission through contaminated meat. While cell-mediated immunity is the main protective mechanism, the contribution of humoral responses, particularly against individual recombinant antigens (rAGs), remains poorly characterized in ovine toxoplasmosis. MethodsWe analyzed the humoral response of lambs experimentally infected with two reference strains of T. gondii (RH and Me49) using different inoculation doses. Recombinant antigens rGra4Gra7, rGra8, rRop2, rCST9, and rBCLA were tested by IgG-ELISA to evaluate their kinetics during infection. Histopathological analyses of brain tissues were performed to assess lesion severity and cyst presence. Additionally, sera from naturally infected sheep were evaluated to test diagnostic performance. ResultsAn early IgG response against rGra4Gra7 and rGra8 was detected, consistent with markers of acute infections. Anti-rBCLA, rRop2, and rCST9 IgG responses were associated with the chronic phase and correlated with cyst burden. Notably, stronger anti-rGra4Gra7 IgG responses tended to associate with lower lesion scores, suggesting a potential protective role. In naturally infected sheep, IgG-ELISA against rGra4Gra7 and rGra8 demonstrated the highest diagnostic performance, outperforming total lysate antigen (TLA)-based assays. ConclusionOur findings highlight distinct kinetics of specific antibody responses against selected T. gondii antigens in sheep, suggesting their value as markers of infection stage and pathology. rGra4Gra7 and rGra8 appear particularly promising both as diagnostic candidates and for exploring mechanisms of humoral modulation in ovine toxoplasmosis.

pathology↗

bioRxiv2025

Defining the cell and molecular origins of the primate ovarian reserve

The primate ovarian reserve is established during late fetal development and consists of quiescent primordial follicles in the ovarian cortex, each composed of granulosa cells surrounding an oocyte in dictate. As late stages of fetal development are not routinely accessible for study with human tissue, we exploited the evolutionary proximity of the rhesus macaque to investigate primate follicle formation. Similar to human prenatal ovaries, the rhesus also develops multiple types of pre-granulosa (PG) cells, with the majority of primordial follicles derived from PG2 with small variable contributions from PG1. We observed that activated medullary follicles recruit fetal theca cells to establish a two-cell system for sex-steroid hormone production prior to birth, providing a cell-based explanation for mini puberty.

developmental biology↗

bioRxiv2024

Immunization with Plant-based Vaccine Expressing Toxoplasma gondii SAG1 Fused to Plant HSP90 Elicits Protective Immune Response in Lambs

Toxoplasma gondii is a protozoan parasite causing toxoplasmosis, a principal concern for public health and livestock industries. Effective vaccination strategies are crucial for controlling toxoplasmosis, particularly in the lamb, which are significant reservoirs of T. gondii. In addition, ovine toxoplasmosis also causes economic losses due to abortions and reproductive complications. In this study, we evaluated two immunization strategies to elucidate the immune protective potential of SAG1 fused to the plant Hsp90 adjuvant against experimental toxoplasmosis in lambs. We performed an oral administration of AtHsp81.2-SAG1HC-infiltrated fresh leaves homogenate (Plant Vaccine) and a subcutaneous administration of recombinant NbHsp90.3-SAG1HC produced in Escherichia coli (Recombinant Vaccine). Our results showed that only the Recombinant Vaccine significantly increased anti-rSAG1 total IgG values. In addition, only lambs immunized with the Plant Vaccine showed a significant increase in IFN-{gamma} serum levels after the experimental infection (evaluated 8 days post-challenge). On the other hand, we also observed a statistically significant decrease in histopathological lesions (injury score) in challenged vaccinated lambs compared to challenged but not vaccinated animals (vehicle and control groups). Finally, to evaluate T. gondii infection, we choose the chimera rGra4-Gra7 as an acute phase protein marker. All lambs from the control and vehicle groups showed higher rates of serological reactivity than lambs from the vaccinated groups, concurrently with increased severity of lesions. These results suggest that both the plant-based and recombinant vaccines are promising candidates for controlling T. gondii infection in lambs, with potential benefits for enhancing public health and animal welfare.

molecular biology↗

bioRxiv2023

Nitrosative stress under microaerobic conditions triggers inositol metabolism in Pseudomonas extremaustralis

Bacteria are exposed to reactive oxygen and nitrogen species that provoke oxidative and nitrosative stress which can lead to macromolecule damage. Coping with stress conditions involves the adjustment of cellular responses, which helps address metabolic challenges. In this study, we performed a global transcriptomic analysis of the response of Pseudomonas extremaustralis to nitrosative stress, induced by S-nitrosoglutathione (GSNO), a nitric oxide donor, under microaerobic conditions. The analysis revealed the upregulation of genes associated with inositol catabolism; a compound widely distributed in nature whose metabolism in bacteria has aroused interest. The RNA-seq data also showed heightened expression of genes involved in essential cellular processes like transcription, translation, amino acid transport and biosynthesis, as well as in stress resistance including iron-dependent superoxide dismutase, alkyl hydroperoxide reductase, thioredoxin, and glutathione S-transferase in response to GSNO. Furthermore, GSNO exposure differentially affected the expression of genes encoding nitrosylation target proteins, encompassing metalloproteins and proteins with free cysteine and /or tyrosine residues. Notably, genes associated with iron metabolism, such as pyoverdine synthesis and iron transporter genes, showed activation in the presence of GSNO, likely as response to enhanced protein turnover. Physiological assays demonstrated that P. extremaustralis can utilize inositol proficiently under both aerobic and microaerobic conditions, achieving growth comparable to glucose-supplemented cultures. Moreover, supplementing the culture medium with inositol enhances the stress tolerance of P. extremaustralis against combined oxidative-nitrosative stress. Concordant with the heightened expression of pyoverdine genes under nitrosative stress, elevated pyoverdine production was observed when myo-inositol was added to the culture medium. These findings highlight the influence of nitrosative stress on proteins susceptible to nitrosylation and iron metabolism. Furthermore, the activation of myo-inositol catabolism emerges as a protective mechanism against nitrosative stress, shedding light on this pathway in bacterial systems, and holding significance in the adaptation to unfavorable conditions.

microbiology↗

bioRxiv2022

An optimized approach for multiplexing single-nuclear ATAC-seq using oligonucleotide conjugated antibodies

BackgroundSingle-cell technologies to analyze transcription and chromatin structure have been widely used in many research areas to reveal the functions and molecular properties of cells at single-cell resolution. Sample multiplexing techniques are valuable when performing single-cell analysis, reducing technical variation and permitting cost efficiencies. Several commercially available methods are available and have been used in many scRNA-seq studies. On the other hand, while several methods have been published, the multiplexing techniques for single nuclear Assay for Transposase-Accessible Chromatin (snATAC)-seq assays remain under development. We developed a simple nucleus hashing method using oligonucleotide conjugated antibodies recognizing nuclear pore complex proteins, NuHash, to perform snATAC-seq library preparations by multiplexing. ResultsWe performed multiplexing snATAC-seq analyses on the mixture of human and mouse cell samples (two samples, 2-plex, and four samples, 4-plex) using NuHash. The demultiplexing accuracy of NuHash was high, and only ten out of 9,144 nuclei (2-plex) and 150 of 12,208 nuclei (4-plex) had discordant classifications between NuHash demultiplexing and discrimination using reference genome alignments. We compared results between snATAC-seq and deeply sequenced bulk ATAC-seq on the same samples and found that most of the peaks detected in snATAC-seq were also detected in deeply sequenced bulk ATAC-seq. The bulk ATAC-seq signal intensity was positively correlated with the number of cell subtype clusters detected in snATAC-seq, but not the subset of peaks detected in all clusters. These subsets of snATAC-seq peaks showed different distributions over different genomic features, suggesting that the peak intensities of bulk ATAC-seq can be used to identify different types of functional loci. ConclusionsOur multiplexing method using oligo-conjugated anti-nuclear pore complex proteins, NuHash, permits high accuracy demultiplexing of samples. The NuHash protocol is straightforward, it works on frozen samples, and requires no modifications for snATAC-seq library preparation.

genomics↗

bioRxiv2022

Overview of the SARS-CoV-2 genotypes circulating in Latin America during 2021

Latin America is one of the regions in which the COVID-19 pandemic has had a stronger impact, with more than 72 million reported infections and 1.6 million deaths until June 2022. Since this region is ecologically diverse and is affected by enormous social inequalities, efforts to identify genomic patterns of the circulating SARS-CoV-2 genotypes are necessary for the suitable management of the pandemic. To contribute to the genomic surveillance of the SARS-CoV-2 in Latin America, we extended the number of SARS-CoV-2 genomes available from the region by sequencing and analyzing the viral genome from COVID-19 patients from seven countries (Argentina, Brazil, Costa Rica, Colombia, Mexico, Bolivia and Peru). Subsequently, we analyzed the genomes circulating mainly during 2021 including records from GISAID database from Latin America. A total of 1534 genome sequences were generated from seven countries, demonstrating the laboratory and bioinformatics capabilities for genomic surveillance of pathogens that have been developed locally. For Latin America, patterns regarding several variants associated with multiple re-introductions, a relatively low percentage of sequenced samples, as well as an increment in the mutation frequency since the beginning of the pandemic, are in line with worldwide data. Besides, some variants of concern (VOC) and variants of interest (VOI) such as Gamma, Mu and Lambda, and at least 83 other lineages have predominated locally with a country-specific enrichments. This work has contributed to the understanding of the dynamics of the pandemic in Latin America as part of the local and international efforts to achieve timely genomic surveillance of SARS-CoV-2.

microbiology↗

bioRxiv2020

Wnt-inducible Lrp6-APEX2 Interacting Proteins identify ESCRT Machinery and Trk-Fused Gene as Components of the Wnt Signaling Pathway

The canonical Wnt signaling pathway serves as a hub connecting diverse cellular physiological processes, such as {beta}-catenin signaling, differentiation, growth, protein stability, macropinocytosis, and nutrient acquisition in lysosomes. We have proposed that sequestration of {beta}-catenin destruction complex components in multivesicular bodies (MVBs) is required for sustained canonical Wnt signaling. In this study, we investigated the events that follow activation of the canonical Wnt receptor Lrp6 using an APEX2-mediated proximity labeling approach. The Wnt co-receptor Lrp6 was fused to APEX2 and used to biotinylate targets that are recruited near the receptor during Wnt signaling at different time periods. Lrp6 proximity targets were identified by mass spectrometry, and revealed that many components of the ESCRT (Endocytic Sorting Components Required for Transport) machinery interacted with Lrp6 within 5 minutes of Wnt3a treatment. This supports the proposal of a central role of multivesicular endosomes in canonical Wnt signaling. Interestingly, proteomic analyses identified the Trk-fused gene (TFG), previously known to regulate the cell secretory pathway and to be rearranged in thyroid and lung cancers, as being strongly enriched in the proximity of Lrp6. We provide evidence that TFG specifically co-localized with MVBs after Wnt stimulation. TFG depletion with siRNA, or knock-out with CRISPR/Cas9, significantly reduced Wnt/{beta}-catenin signaling in cell culture. In vivo, studies in the Xenopus system showed that TFG is required for endogenous Wnt-dependent embryonic patterning. The results suggest that the multivesicular endosomal machinery and the novel player TFG have important roles in Wnt signaling. SignificanceWnt/{beta}-catenin signaling is a conserved pathway involved in cell differentiation and in the regulation of many other processes, including cell growth and proliferation, macropinocytosis, and cell metabolism. Endocytosis is required to regulate Wnt signaling, but the precise factors at play are still elusive. Here, we describe a biotin-dependent proximity labeling approach using ascorbate peroxidase-tagged Lrp6, a Wnt co-receptor. Proteomic analysis of biotinylated-enriched targets identified numerous multivesicular endosome proteins that were recruited to the receptor shortly after addition of Wnt protein. Additionally, we identified the protein TFG as one of the strongest interactors with Lrp6. TFG co-localized with Wnt-induced multivesicular endosomes. Xenopus embryo assays revealed that TFG is required in vivo for canonical Wnt signaling.

cell biology↗

bioRxiv2017

Differentiation of primate primordial germ cell-like cells following transplantation into the adult gonadal niche

A major challenge in stem cell differentiation validation is the availability of bioassays to prove cell types generated in vitro are equivalent to cells in vivo. In the mouse model, differentiation of primordial germ cell-like cells (PGCLCs) from pluripotent cells was validated by transplantation, leading to the generation of spermatogenesis and to the birth of offspring. Here we report the use of xenotransplantation (monkey to mouse) and homologous transplantation (monkey to monkey) to validate our in vitro protocol for differentiating male rhesus macaque PGCLCs (rPGCLCs) from rhesus macaque induced pluripotent stem cells (riPSCs). Specifically, transplantation of aggregates containing rPGCLCs into mouse and nonhuman primate testicles overcomes a major bottleneck in rPGCLC differentiation with the expression of VASA and MAGEA4, but not ENO2. These findings suggest that immature rPGCLCs once transplanted into an adult gonadal niche commit to differentiate towards late PGCs and spermatogonia-like cells but do not complete the conversion into ENO2-positive spermatogonia.

developmental biology↗