Biology subjects

Delgado, I.

Publications and source records attributed to Delgado, I..

5 recordsLinked to original sources

bioRxiv2026

Early vegetative development and ontogenetic phase transitions in Juglans neotropica Diels: a BBCH-scale approach

Juglans neotropica is an endangered South American walnut species for which standardized descriptions of early development are lacking, limiting its effective use in conservation and restoration programs. We developed a BBCH-scale description of early vegetative growth of J. neotropica based on observations under nursery and field conditions in Colombia. Three principal vegetative stages were described: seed germination (stage 0), leaf development (stage 1), and stem elongation (stage 3). Germination was hypogeal and occurred 30-140 d after sowing, occasionally extending to 180 d. During early growth, leaflet morphology, number, and architecture showed consistent and discrete changes between stages 1 and 3, including shifts in apex, base, margin type, and laminar shape. These modifications indicate that early development is organized into distinct ontogenetic phases rather than continuous variation, marking the transition from juvenile to vegetative adult stages. By providing a standardized, development-based framework independent of chronological age, this BBCH scale facilitates accurate identification and monitoring of seedlings in nursery production, restoration projects, and urban forestry programs. More broadly, this approach contributes to the characterization of ontogenetic phase transitions in tropical tree species and supports the use of development-based criteria for managing early establishment and performance.

plant biology↗

bioRxiv2023

Spatial enhancer activation determines inhibitory neuron identity

The mammalian telencephalon contains a tremendous diversity of GABAergic projection neuron and interneuron types, that originate in a germinal zone of the embryonic basal ganglia. How genetic information in this transient structure is transformed into different cell types is not yet fully understood. Using a combination of in vivo CRISPR perturbation, lineage tracing, and ChIP-seq in mice, we found that the transcription factor MEIS2 favors the development of projection neurons through genomic binding sites in regulatory enhancers of projection neuron specific genes. MEIS2 requires the presence of the homeodomain transcription factor DLX5 to direct its functional activity towards these sites. In interneuron precursors, the activation of projection neuron specific enhancers by MEIS2 and DLX5 is repressed by the transcription factor LHX6. When MEIS2 carries a mutation associated with intellectual disability in humans, it is less effective at activating enhancers involved in projection neuron development. This suggests that GABAergic differentiation may be impaired in patients carrying this mutation. Our research supports a model ("Differential Binding ) where the spatial specific composition of transcription factors at cis-regulatory elements determines differential gene expression and cell fate decisions in the ganglionic eminence.

developmental biology↗

bioRxiv2022

Statistical evaluation of metaproteomics and 16s rRNA amplicon sequencing techniques for the study of the gut microbiota establishment of infants with cystic fibrosis

The newborn screening for cystic fibrosis (CF) can identify affected but still asymptomatic infants. The selection of omic technique for gut microbiota study is therefore crucial due to both the small amount of feces available and the low microorganism load. Our aim was to compare the agreement between 16S rRNA amplicon sequencing and metaproteomics by a robust statistical analysis including McNemar (taxa presence) test and Bland-Altman (taxa abundance) data plotting for studying the sequential establishment of the gut microbiota during the first year of life in 8 infants with CF (28 fecal samples). The taxonomic assignation was similar by the two techniques, whereas certain discrepancies were observed in the abundance detection, mostly the underrepresentation of Bifidobacterium and the overestimation of certain Firmicutes and Proteobacteria by amplicon sequencing. During the first months of life, the CF gut microbiota is characterized by poor alpha diversity, a significant enrichment of Ruminococcus gnavus, the expression of certain virulent bacterial traits, and the detection of human inflammation-related proteins. Our study provides an extended comparative analysis with robust statistical support that could optimize the use of both approaches for gut microbiota research. Metaproteomics provides information on composition and functionality, as well as data on host-microbiome interactions. Its strength is the identification and quantification of Actinobacteria and certain classes of Firmicutes. Both techniques detected an aberrant microbiota in infants with CF during their first year of life, dominated by the enrichment of R. gnavus within a human inflammatory environment.

microbiology↗

bioRxiv2022

TP53 knockout in MCF7 breast cancer cells induces sensitivity to fluoropyrimidine drugs.

TP53 mutations are present in all molecular subtypes of breast cancer and often correlate with decreased survival; however, few therapeutic options exist for patients with TP53-mutant breast cancers. To discover therapeutic strategies for these patients, we investigated the sensitivity of 129 FDA-approved chemotherapies to TP53-KO and TP53-WT MCF7 breast adenocarcinoma cells and found p53 loss to confer sensitivity to 5-fluorouracil (5-FU). We then treated the p53-null cells and isogenic controls with F10, a second-generation polymeric fluoropyrimidine, and found this preferential cytotoxicity of TP53-KO cells to be significantly magnified. F10 killing could only minimally be rescued by addition of exogenous uridine, whereas it was completely abrogated by addition of exogenous thymidine, suggesting DNA incorporation to be central to the cytotoxic mechanism of action. Furthermore, F10 killing of p53-null cells was persistent even in heterogeneous cellular mixtures more reflective of natural tumor evolution. Together, our results suggest F10 may widen the therapeutic window for TP53-mutant breast cancer by enhancing genotoxicity in cells resistant to apoptosis.

cancer biology↗

bioRxiv2020

Axial skeleton anterior-posterior patterning is regulated through feedback regulation between Meis transcription factors and retinoic acid

Vertebrate axial skeletal patterning is controlled by coordinated collinear expression of Hox genes and axial level-dependent activity of Hox protein combinations. Transcription factors of the Meis family act as cofactors of Hox proteins and profusely bind to Hox complex DNA, however their roles in mammalian axial patterning have not been established. Similarly, retinoic acid (RA) is known to regulate axial skeletal element identity through the transcriptional activity of its receptors, however, whether this role is related to Meis/Hox activity in axial patterning remains unknown. Here we study the role of Meis in axial skeleton formation and its relationship to the RA pathway by characterizing Meis1, Meis2 and Raldh2 mutant mice. Meis elimination produces axial skeleton defects without affecting Hox gene transcription, including vertebral homeotic transformations and rib mis-patterning associated to defects in the hypaxial myotome. While Raldh2 and Meis positively regulate each other, Raldh2 elimination largely recapitulates the defects associated to Meis-deficiency and Meis overexpression rescues the axial skeletal defects in Raldh2 mutants. We propose a Meis-RA positive feedback loop whose output is Meis levels and is essential to establish anterior-posterior identities and pattern of the vertebrate axial skeleton.

developmental biology↗