Biology subjects

Garcia, L. E.

Publications and source records attributed to Garcia, L. E..

6 recordsLinked to original sources

bioRxiv2026

Plastome convergence across heterotrophic plant lineages: genome reduction, extreme AT bias, high substitution rates, and functional persistence in the endoparasitic Mitrastemonaceae

The loss of photosynthesis triggers extreme plastid genome (ptDNA) decay, including complete genome loss. Of the multiple transitions to heterotrophy among angiosperms, the ptDNA status remains poorly defined in lineages such as the endophytic Mitrastemonaceae (Ericales). Adopting a panplastome perspective, we characterized genomic variation across Mitrastemon yamamotoi individuals, assembling two complete circular ptDNAs and re-evaluating all available genomic resources for the genus. Our results reveal a highly minimized ptDNA (18-26 kb) with extreme AT content (>77%) and loss of the typical quadripartite architecture. Despite the absence of the stabilizing inverted repeats, the Mitrastemon panplastome exhibits remarkable structural stability and collinearity among individuals. The reduced suite of 26 genes, which includes accD, infA, clpP, ycf1, ycf2, and the essential tetrapyrrole precursor trnE-UUC, exhibit elevated substitution rates. Evolutionary rate analyses (dN/dS) demonstrate that the core ribosomal suite remains under strong purifying selection ({omega}<1), confirming the organelles functional status. Furthermore, transcriptomic analysis identified a nearly complete set of nuclear-encoded DNA-RRR genes, with the notable exception of the MUTS2 surveillance system. The convergent loss of these homologs in Mitrastemon and another holoparasitic lineage may be linked to the shared structural instability and mutational bias. Our findings demonstrate that despite extreme genome compaction, accelerated substitution rates, and severe AT-bias, the Mitrastemon panplastome remains quite stable, providing a definitive genomic framework for understanding plastid evolution within the endoparasitic Mitrastemonaceae.

evolutionary biology↗

bioRxiv2025

Circle-Mediated HGT shapes the multichromosomal mitochondrial genome of the endoparasite Mitrastemon yamamotoi

Horizontal gene transfer (HGT), a well-established driver of genome evolution in prokaryotes, was historically considered rare in plants. However, accumulating genomic evidence supports its occurrence in angiosperms, impacting both nuclear and mitochondrial genomes, particularly in parasitic species that establish vascular connections with their hosts. Despite the increasing recognition of HGT in a few clades of parasitic plants (e.g., Balanophoraceae, Rafflesiaceae, and Cynomoriaceae), the underlying mechanisms and evolutionary consequences of these transfers are still not fully understood. Mitrastemon yamamotoi, a holoparasitic endoparasite in the order Ericales, invades the roots of host trees in the Fagaceae family, creating favorable conditions for HGT. In this study, we assembled for the first time the mtDNA of Mitrastemon, revealing a multipartite structure consisting of 51 circular-mapping chromosomes. Phylogenetic and comparative genomic analyses uncovered extensive HGT from Fagaceae hosts, affecting both coding and non-coding regions. Notably, more than 60% of the Mitrastemon mtDNA is of foreign origin, and seven chromosomes are entirely foreign, with structural signatures in the donor mtDNA consistent with the recently proposed circle-mediated HGT model. Additionally, we detected six protein-coding genes of foreign origin and one chimeric gene. Remarkably, a foreign atp1 gene has replaced the missing native copy and represents a rare event of functional HGT in plant mitochondria. These results position Mitrastemon as a valuable model for studying mtDNA evolution and deepening our understanding of the HGT process. Our findings expand the range of lineages in which circle-mediated HGT has been documented, suggesting it is a more widespread and fundamental mode of mitochondrial HGT in plants. Significant StatementParasitic plants form intimate connections with their hosts, but how these interactions influence genome evolution remains poorly understood. Our study shows that Mitrastemon yamamotoi has acquired over 60% of its mitochondrial DNA from its host through horizontal gene transfer, including entire foreign chromosomes. These findings provide strong support for a recently proposed mechanism, circle-mediated HGT, and suggest that this process may be a more widespread driver of mitochondrial genome evolution in flowering plants.

evolutionary biology↗

bioRxiv2024

Time- and Dose-dependent Effects of CIGB-300 in the lung squamous cell carcinoma proteomics.

Proteome-wide scale in a dose- and time-depending setting is crucial in drug-regulated proteomics to fully understand the pharmacological mechanism of anticancer drugs as well as the identification of proteins suitable for drug response biomarkers. Here, we investigated the effect of the CIGB-300 anticancer peptide at IC50 and IC80 dose levels during 1 and 4 hours of treatment on squamous lung cancer cell (NCI-H226) proteome. A dose-dependent inhibitory effect of the global proteomics while slight change of the upregulated proteins was observed, by increasing CIGB-300 dose level. The biological processes that were more represented among the modulated proteins were those related to small molecule biosynthetic process, pyridine-containing compound metabolic process and nucleobase-containing small molecule metabolism. Importantly, NSCLC previously described biomarkers and Protein Kinase CK2 substrates were significantly modulated by treating both doses of CIGB-300. These proteins, which are associated with both metabolism and cell survival, reinforce the hypothesis of the therapeutic potential of CIGB-300 as anticancer treatment for squamous non-small cell lung cancer and merits be validated as CIGB-300 response biomarkers in NSCLC patients. Overall, our proteomics-guided strategy based on time and drug dose served not only to deep into the mechanism of action of CIGB-300 but also to identify candidate proteins for pharmacodynamic and drug response biomarkers.

cancer biology↗

bioRxiv2023

Break-induced replication is the primary recombination pathway in plant somatic hybrid mitochondria: a model for mt-HGT

Somatic hybrids between distant species offer a remarkable model to study genomic recombination events after mitochondrial fusion. Recently, our lab described highly chimeric mitogenomes in two somatic hybrids between the Solanaceae Nicotiana tabacum and Hyoscyamus niger resulting from interparental homologous recombination. To better examine the recombination map in somatic hybrid mitochondria, we developed a more sensitive bioinformatic strategy to detect recombination activity based on high-throughput sequencing without assembling the hybrid mitogenome. We generated a new intergeneric somatic hybrid and re-analyzed the two Solanaceae somatic hybrids. We inferred 213 homologous recombination events across repeats of 2.1 kb on average. Most of them ([~]80%) were asymmetrical, consistent with the break-induced replication (BIR) pathway. Only rare (2.74%) non-homologous events were detected. Interestingly, independent events frequently occurred in the same regions within and across somatic hybrids, suggesting the existence of recombination hotspots in plant mitogenomes. BIR is the main pathway of interparental recombination in somatic hybrid mitochondria. Likewise, under the fusion compatibility model of mitochondrial horizontal transfer, foreign mitochondria fuse with those in the recipient cell and their genomes likely recombine via BIR, resulting in the integration and/or loss of mitochondrial DNA. Findings of this study are also relevant to mitogenome editing assays. HighlightWe show that the chimeric mitochondrial genomes of somatic hybrids result from one of the three described homologous recombination pathways (BIR), mimicking the fusion compatibility model for plant HGT.

molecular biology↗

bioRxiv2019

Gene expression is associated with virulence in murine macrophages infected with Leptospira spp

Leptospira genus contains species that affect human health with varying degrees of pathogenicity. In this context, we aimed to evaluate the differences in modulation of host gene expression by strains of Leptospira with varied virulence degrees. Our data showed a high number of differentilly expressed transcripts in murine macrophages following 6h of infection with both virulent and culture-attenuated L. interrogans and to a lesser degree, with the saprophyte strain L. biflexa. That suggests that certain genes are modulated by Leptospira infection independent of their degree of virulence, whether others are virulence and species associated. Pathway analysis indicated that Apoptosis, ATM Signaling and Cell Cycle: G2/M DNA Damage Checkpoint Regulation were exclusively regulated following infection with the virulent strain. Results demonstrated that species and virulence play a role during host response to Leptosppira spp in murine macrophages.\n\nAuthor summaryLeptospirosis is an infectious disease that is transmitted from animals to humans. It is a re-emerging neglected zoonosis that is found in a range of environments worldwide, most notably tropical regions prone to flooding. This bacteria is found in soil and water and are eliminated in the urine by rats, their natural host reservoir. Through skin contacts with the bacteria people or animals can get infected however the infection process is still poorly understood, such as the fact that different strains can cause different severity of illness. In this study, we aimed to evaluate the differences in modulation of host gene expression by strains of Leptospira varying in virulence. After transcriptomic analysis, the results showed a high number of differentially expressed genes after 6h of infection by virulent and attenuated L. interrogans, and to a lesser extent with L. biflexa saprophytic lineage. This suggests that RNAs are modulated after infection by Leptospira in macrophages, in a species and virulence related manner. It is hoped that the data produced will contribute to further our understanding on the pathogenesis of leptospirosis.

molecular biology↗

bioRxiv2018

Elucidating genomic patterns and recombination events in plant cybrid mitochondria

The maintenance of a dynamic equilibrium between the mitochondrial and nuclear genomes requires continuous communication and a high level of compatibility between them, so that alterations in one genetic compartment need adjustments in the other. The co-evolution of nuclear and mitochondrial genomes has been poorly studied, even though the consequences and effects of this interaction are highly relevant for human health, as well as for crop improvement programs and for genetic engineering. The mitochondria of plants represent an excellent system to understand the mechanisms of genomic rearrangements, chimeric gene formation, incompatibility between nucleus and cytoplasm, and horizontal gene transfer. We carried out detailed analyses of the mitochondrial genome (mtDNA) of a repeated cybrid between the solanaceae Nicotiana tabacum and Hyoscyamus niger. The mtDNA of the cybrid was intermediate between the size of parental mtDNAs and the sum of them. Noticeably, most of the homologous sequences inherited from both parents were lost. In contrast, the majority of the sequences exclusive of a single parent were maintained. The mitochondrial gene content included a majority of N. tabacum derived genes, but also chimeric, two-parent derived, and H. niger-derived genes in a tobacco nuclear background. Any of these alterations in the gene content could be the cause of CMS in the cybrid. The parental mtDNAs interacted through 28 homologous recombination events and a single case of illegitimate recombination. Three main homologous recombination mechanisms were recognized in the cybrid mitochondria. Break induced replication (BIR) pathway was the most frequent. We propose that BIR could be one of the mechanisms responsible for the loss of the majority of the repeated regions derived from H. niger.

molecular biology↗