Biology subjects

Campos, P.

Publications and source records attributed to Campos, P..

5 recordsLinked to original sources

bioRxiv2026

Differential control of corticotroph Ca2+ signalling by corticotrophin-releasing hormone and arginine vasopressin

Corticotroph cells convert hypothalamic inputs into adrenocorticotrophic hormone secretion via intracellular calcium (Ca2+) signalling, but how they integrate corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) across physiological concentration ranges remains unclear. Here, we quantified intracellular Ca2+ responses in isolated rat corticotrophs to CRH and AVP, applied alone and in combination, to characterise response magnitude, temporal dynamics, and cell recruitment. Both secretagogues increased Ca2+ signalling in a concentration-dependent manner, but with distinct effects: AVP generally evoked larger responses, faster response onset, and greater cell recruitment than CRH when applied alone. Under co-stimulation, increasing CRH concentration increased the proportion of cells classified as synergistic without altering positive synergy values, suggesting CRH-dependent control of interaction likelihood rather than interaction strength. Marked cell-to-cell heterogeneity was observed across all conditions, consistent with corticotroph subpopulations differing in activation thresholds. Together, these findings show that AVP drives broad corticotroph recruitment, whereas CRH modulates how corticotrophs integrate convergent inputs, defining complementary roles in shaping pituitary output.

neuroscience↗

bioRxiv2025

Novel clonal lineages of wheat stem rust in the Southern Cone of South America

Puccinia graminis f. sp. tritici (Pgt) causes wheat stem rust, a devastating disease of cereals. Recent approaches to examine populations at a genomic level have provided valuable information on the genotypic diversity of Pgt populations in Africa, Europe and North America and evolutionary mechanisms underlying the emergence of new races. However, an in-depth characterisation of Pgt populations in South America has been lacking. To bridge this knowledge gap, 91 Pgt isolates were collected from Argentina and Uruguay in 2020 and 2021 and used to generate transcriptome and whole genome sequence data and pathotype information. Phylogenetic analyses revealed that this South American Pgt population includes three clonal lineages, two of which have not been detected elsewhere. The third lineage is globally dispersed, including isolates from Africa and the Middle East. The predominant lineage, unique to South America, encompassed 90% of the samples and showed related pathotypes differing by virulence on single resistance genes consistent with evolution by stepwise mutation within the clonal lineage. There was no evidence of sexual recombination giving rise to new genetic diversity in this population. These observations urge to routinely incorporate and compare genotypic data from South American Pgt isolates to surveillance data from other geographic regions.

evolutionary biology↗

bioRxiv2022

Herbarium Specimen Sequencing Allows Precise Datation of Xanthomonas citri pv. citri Diversification History

Over the past decade, the field of ancient genomics has triggered considerable progress in the study of various pathogens, including those affecting crops. In this context, herbarium collections have been an important source of dated, identified and preserved DNA, whose use in comparative genomics and phylogeography may shed light into the emergence and evolutionary history of plant pathogens. In this study, we reconstructed 13 historical genomes of the bacterial crop pathogen Xanthomonas citri pv. citri (Xci) from infected citrus herbarium specimens using a shotgun-based deep sequencing strategy. Following authentication of the historical genomes based on ancient DNA damage patterns, we compared them to a large set of modern genomes to reconstruct their phylogenetic relationships, pathogeny-associated genes content and estimate several evolutionary parameters, using Bayesian tip-dating calibration and phylogeography inferences. Our results reveal that Xci originated in Southern Asia ~11,500 years ago and diversified during the beginning of the 13th century, after Citrus diversification and before spreading to the rest of the world. This updated scenario links Xci specialization to Neolithic climatic change and the development of agriculture, and its diversification to the human-driven expansion of citriculture through the early East-West trade and later colonization. The analysis of data obtained from such historical specimens is challenging and must undergo adapted treatment before being compared to modern samples. Nevertheless, we confirm here that herbarium collections are a precious tool to improve the knowledge of the evolutionary history of plant pathogens.

evolutionary biology↗

bioRxiv2022

Specialized Tfh cell subsets driving type-1 and type-2 humoral responses in lymphoid tissue

Effective antibody responses are essential to generate protective humoral immunity. Different inflammatory signals polarize T cells towards an appropriate effector phenotype during an infection or immunization. Th1 and Th2 cells have been associated with the polarization of humoral responses for several decades. However, it is now established that T follicular helper cells (Tfh) have a unique ability to access the B cell follicle and support the Germinal Centre (GCs) responses by providing help to B cells. We investigated the specialization of Tfh cells induced under type-1 and type-2 conditions. We first studied homogenous Tfh cell populations generated by adoptively transferred TCR-transgenic T cells in mice immunized with type-1 and type-2 adjuvants. Using a machine learning approach, we established a gene expression signature that discriminates Tfh cells polarized towards type-1 and type-2 response, defined as Tfh1 and Tfh2 cells. The Tfh1 and Tfh2 distinct signature was validated against datasets of Tfh cells induced following LCMV or helminth infection. Using single-cell transcriptomics, we also dissected the heterogeneity of Tfh cells from the two immunizing conditions. Our results show that Tfh cells acquire a specialized function under distinct types of immune responses, but with the coexistence of a small population of Tfh cells of the alternative type. Furthermore, the specific molecular hallmarks of Tfh1 and Tfh2 cells identified herein offer putative new targets for tuning humoral responses.

immunology↗

bioRxiv2018

Functional specialization under multidimensional tradeoffs

Although tradeoffs are expected to play an essential role in shaping the diversity in a community, their effects remain relatively nebulous and notoriously difficult to assess. This is especially true when multiple tradeoffs occur simultaneously. When dealing with single tradeoffs some information can be predicted based on their curvature. Does the same happen when dealing with multiple tradeoffs? What happens if the tradeoffs have opposing curvatures? To address these issues, we develop a resource-based model that encompasses multiple tradeoffs mediated by the acquisition and processing of the resources. The model considers a spatially structured population of microbial organisms that can grow on an arbitrary number of resources, which come into the system at a constant rate and diffuse through the environment. The individuals can adopt a variety of strategies through mutation constrained by tradeoffs, which renders the model adaptive. We assess population sizes and levels of ecological specialization. We find that when multiple tradeoffs are considered the classical intuition developed for single tradeoffs does not hold. The outcome can depend significantly not only on the curvature of the tradeoffs but also on resource availability.

ecology↗