Biology subjects

Crespo, J. L.

Publications and source records attributed to Crespo, J. L..

5 recordsLinked to original sources

bioRxiv2026

Quantitative Ultrasound Analysis of Gas Embolic Disease in Bycaught Sea Turtles

ObjectivesBycatch-related decompression after forced submersion can result in severe gas embolic disease in sea turtles. This work used qualitative and quantitative ultrasound analyses, including gas grading, brightness analysis, and texture feature extraction, to investigate organ-specific gas burden and temporal evolution in the hearts, kidneys, and livers of bycaught sea turtles. Materials and MethodsUltrasound imaging of the hearts, kidneys, and livers of bycaught turtles was performed as part of veterinary evaluation either onboard fishing vessels immediately after surfacing (boat group, n=47) or after longer periods at shore-based facilities (shore group, n=30). Gas burden in each ultrasound scan was graded on an ordinal scale from 0 (no gas) to 5 (gas completely shadowing organ anatomy). Temporal differences in gas burden were compared between the shore and boat groups. Quantitative brightness and texture features were extracted from all organs, including contrast, correlation, homogeneity, and energy from liver and kidney data. A multivariate logistic regression model with leave-one-out cross-validation was conducted, with shore versus boat as a binary outcome (surrogate of post-surfacing decompression state) and ultrasound texture metrics as independent variables. ResultsMedian grades from the first ultrasound scan were significantly higher in the boat group than in the shore group for the liver, kidney, and heart (3, 3, and 3 vs 1, 1, and 0, respectively). This pattern coincided with a difference in the mean duration until the first scan which was conducted being 54 min for the onboard studies vs 330 minutes in the shore group. Mean pixel brightness within cardiac and liver regions of interest increased with rising bubble grade before decreasing at the highest grades, consistent with acoustic shadowing at severe gas burden. Texture features demonstrated significant organ-specific changes with increasing gas burden, and the regression models achieved areas under the receiver operating characteristic curve of 0.92 for liver texture features and 0.83 for kidney texture features. ConclusionsThese findings demonstrate organ-specific differences in gas evolution over time. Quantitative ultrasound features were associated with gas burden and post-surfacing interval in bycaught sea turtles. These findings support the feasibility of quantitative ultrasound biomarkers for assessment of decompression-related gas burden.

physiology↗

bioRxiv2026

The cyanobacterium Anabaena uses pleomorphism as an acclimation strategy to high light stress

O_LIPhytoplankton species display characteristic morphologies that are generally assumed to confer adaptive advantages, yet the functional significance of cell shape remains poorly understood. Here, we investigated whether pleomorphism contributes to acclimation to changing light environments. C_LIO_LIUsing the cyanobacterium Anabaena sp. PCC 7120 as a model system, we combined molecular genetics, microscopy, physiological measurements and biophysical analyses to determine how morphology is regulated and how it affects photosynthetic performance under different light intensities. C_LIO_LIWe show that Anabaena undergoes a reversible light-dependent morphological transition from rod-shaped cells under low light to large globular cells under high light stress. This transition is controlled by the relative activities of the elongasome and class A penicillin-binding proteins and is accompanied by thylakoid reorganization. The globular morphology reduces light absorption and enables cells to maintain photosynthetic activity under photoinhibitory conditions. C_LIO_LIOur findings establish a mechanistic link between cell-wall remodelling, cellular optics and photosynthetic performance, revealing pleomorphism as a dynamic acclimation strategy to high light stress. More broadly, this work provides experimental support for the packaging effect and highlights morphology as an active determinant of phytoplankton fitness. C_LI

plant biology↗

bioRxiv2025

The yellow-in-the-dark chIL Chlamydomonas mutant as a model for time-resolved chloroplast biogenesis and physiological responses to lincomycin

Understanding chloroplast biogenesis is key given the importance of photosynthesis and chloroplast metabolism. Chloroplast assembly has been extensively studied in angiosperms, where the main hallmarks have been established, including the need for nuclear and plastid genome coordination through anterograde and retrograde signals. However, recent works in other photosynthetic lineages have revealed both divergent and conserved regulators. These differences likely represent adaptive strategies that emerged during the evolution of the green lineage, and highlight the need for evolutionary studies to fully elucidate the mechanisms controlling chloroplast biogenesis, a light-promoted process. Here, we characterize the yellow-in-the-dark chIL mutant of Chlamydomonas reinhardtii, which carries a mutation in the CHLL subunit of the dark-operative POR enzyme. Dark-adapted chIL cells cannot synthesize chlorophylls and display a de-differentiated chloroplast, and our results show that upon exposure to light, chloroplast biogenesis is initiated very rapidly based on starch reserves. We demonstrate that accumulation of pigments, photosynthesis-related proteins, and functional chloroplast activity is detected within 1-3 hours of illumination. Additionally, we show that lincomycin, an inhibitor of plastid translation, specifically affects chloroplast physiology, and blocks light-induced chloroplast biogenesis and cell growth, establishing lincomycin as a valuable tool for investigating chloroplast physiology and plastid-to-nucleus signals in Chlamydomonas. Together, this study introduces the chIL mutant as a powerful model system to dissect light-induced, time-resolved chloroplast biogenesis, as well as the responses and signaling triggered by lincomycin. By promoting broader adoption of this model, we aim to help inform strategies to enhance photosynthesis and stress tolerance, and optimize bioproduct production.

plant biology↗

bioRxiv2020

Tudor staphylococcal nuclease acts as a docking platform for stress granule components in Arabidopsis thaliana

Adaptation to stress depends on the modulation of gene expression. Regulation of mRNA stability and degradation in stress granules (SGs), - cytoplasmic membraneless organelles composed of messenger ribonucleoprotein (mRNP) complexes, - plays an important role in fine-tuning of gene expression. In addition, SG formation can modulate stress signaling pathways by protein sequestration. Molecular composition, structure, and function of SGs in plants remain obscure. Recently, we established Tudor Staphylococcal Nuclease (TSN or Tudor-SN; also known as SND1) as integral component of SGs in Arabidopsis thaliana. Here, we combined purification of TSN interactome with cell biology, reverse genetics and bioinformatics to study composition and function of SGs in plants. We found that under both normal (in the absence of stress) and stress conditions TSN interactome is enriched in the homologues of known mammalian and yeast SG proteins, in addition to novel or plant-specific SG components. We estimate that upon stress perception, approximately half of TSN interactors are recruited to SGs de novo, in a stress-dependent manner, while another half represent a dense protein-protein interaction network pre-formed before onset of stress. Almost all TSN-interacting proteins are moderately or highly disordered and approximately 20% of them are predisposed for liquid-liquid phase separation (LLPS). This suggests that plant SGs, similarly to mammalian and yeast counterparts, are multicomponent viscous liquid droplets. Finally, we have discovered that evolutionary conserved SNF1-related protein kinase 1 (SnRK1) interacts with TSN in heat-induced SGs and that SnRK1 activation critically depends on the presence of TSN and formation of SGs. Altogether, our results establish TSN as a docking platform for SG-associated proteins and important stress signal mediator in plants.

plant biology↗

bioRxiv2018

Investigating the effect of Target of Rapamycin kinase inhibition on the Chlamydomonas reinhardtii phosphoproteome: from known homologs to new targets

O_LITarget of Rapamycin (TOR) kinase is a conserved regulator of cell growth whose activity is modulated in response to nutrients, energy and stress. Key proteins involved in the pathway are conserved in the model photosynthetic microalga Chlamydomonas reinhardtii, but the substrates of TOR kinase and downstream signaling network have not been elucidated. Our study provides a new resource for investigating the phosphorylation networks governed by the TOR kinase pathway in Chlamydomonas.\nC_LIO_LIWe used quantitative phosphoproteomics to investigate the effects of inhibiting Chlamydomonas TOR kinase on dynamic protein phosphorylation. Wild-type and AZD-insensitive Chlamydomonas strains were treated with TOR-specific chemical inhibitors (rapamycin, AZD8055 and Torin1), after which differentially affected phosphosites were identified.\nC_LIO_LIOur quantitative phosphoproteomic dataset comprised 2,547 unique phosphosites from 1,432 different proteins. Inhibition of TOR kinase caused significant quantitative changes in phosphorylation at 258 phosphosites, from 219 unique phosphopeptides.\nC_LIO_LIOur results include Chlamydomonas homologs of TOR signaling-related proteins, including a site on RPS6 with a decrease in phosphorylation. Additionally, phosphosites on proteins involved in translation and carotenoid biosynthesis were identified. Follow-up experiments guided by these phosphoproteomic findings in lycopene beta/epsilon cyclase showed that carotenoid levels are affected by TORC1 inhibition and carotenoid production is under TOR control in algae.\nC_LI

plant biology↗