Biology subjects

Martin, C. A.

Publications and source records attributed to Martin, C. A..

8 recordsLinked to original sources

bioRxiv2026

Ontogenetic consequences of developmental temperature in amphibians: simultaneous gains in heat tolerance and cumulative costs to stress physiology

Heat tolerance is critical for ectotherms facing environmental temperature variability, yet how it varies across life stages, and whether trade-offs occur between temperature-induced developmental plasticity and heat tolerance, remain unclear, particularly in organisms undergoing metamorphosis which represent 95% of all animal species. We examined how early-life thermal conditions shape growth, development, survival, acclimation capacity, heat tolerance, and energy allocation across ontogeny in the African clawed frog (Xenopus laevis), reared at six constant temperatures (17-32{degrees}C). We tested whether higher developmental temperatures generate trade-offs between accelerated growth and heat tolerance, and the consequences for post-metamorphic resilience to extreme heat. Rearing at 32{degrees}C was lethal before metamorphosis. At non-lethal warm temperatures (17-29{degrees}C), larvae and juveniles simultaneously accelerated development, maintained growth, and enhanced heat tolerance. However, juveniles reared at 29{degrees}C showed reduced survival, elevated corticosterone responses to acute stress, and diminished acclimation capacity, indicating increased energetic demands and constrained metabolic flexibility. These findings show that amphibians can integrate developmental plasticity with plastic adjustments in heat tolerance, but that such strategies incur cumulative physiological costs. By adopting an across-life-stage approach, our study highlights energy-allocation constraints that may limit population persistence under climate warming in species with complex life cycles.

ecology↗

bioRxiv2025

Identifying the exposure of taxonomic, functional, and phylogenetic diversity of steppe birds to renewable energy developments

Biodiversity is globally threatened by human impacts including land use transformation and climate change. Global warming has prompted a rapid transition from fossil fuels to cleaner energy sources such as photovoltaic (PV) energy. However, utility-scale PV plants demand vast areas and can lead to conflicts with biodiversity conservation, making strategic planning essential. We evaluate the spatial overlap between conservation priorities and PV infrastructure using steppe birds--a highly threatened bird group occurring in lands potentially suitable for PV plants--as a model. First, we quantified and mapped taxonomic (TD), functional (FD), and phylogenetic diversity (PD) of 26 species across a main stronghold for European steppe birds (mainland Spain and Balearic Islands) to identify prioritization scenarios that best preserved all steppe bird diversity facets (TD, FD, and PD), and steppe birds of conservation concern. Next, we generated a diversity hotspot map based on the combination of TD, FD, and PD and overlapped with existing PV infrastructure to determine: (1) exposure areas (high diversity hotspots with high PV occupancy), and (2) no-go areas (high diversity hotspots with low/null PV occupancy). We found that the prioritization scenario combining TD+FD+PD retained 68.5% of TD, 75.5% of FD, 59.7% of PD, and 62.8% of areas with species of conservation concern, providing a more balanced representation across biodiversity facets than other prioritization scenarios. PV infrastructure currently occurs in 53.1% of high diversity hotspot cells. Overall, exposure areas (7.2% of the study area) were mainly concentrated in Central, Southern, and Northwestern Spain, while no-go areas (19.9% of the study area) were concentrated in Northern, Central, and Central-Western Spain. Our methodology is adaptable to other species, communities and regions, offering a robust framework for balancing development projects with biodiversity conservation. As the transition to renewable energy accelerates, including biodiversity in energy planning is crucial for preventing irreversible ecological losses.

ecology↗

bioRxiv2025

A transcriptional atlas of early Arabidopsis seed development suggests mechanisms for inter-tissue coordination

Successful seed development is essential for flowering plant reproduction and requires the coordination of three genetically distinct tissues: the embryo and endosperm, which are the products of fertilization, and the maternal seed coat. Our understanding of the transcriptional programs underlying tissue-specific functions and inter-tissue coordination in seeds remains incomplete. To address this, we performed single nucleus RNA-sequencing on Arabidopsis thaliana seeds at 3, 5, and 7 days after pollination. We characterize all major seed cell or nuclei types, further refine transcriptional states in the endosperm, and map signatures of selection on cell type-specific genes. Among other findings, our analyses reveal the compartmentalization of genes involved in brassinosteroid-responsive transcription factor activation, abundant endosperm expression of genes that encode short, secreted peptides (SSPs), and expression enrichment of rapidly evolving genes in endosperm and seed coat subtypes, illuminating the cell type and species specificity of seed genes.

plant biology↗

bioRxiv2025

Growth but not corticosterone, oxidative stress or telomere length is negatively affected by microplastic exposure in a filter-feeding amphibian

Microplastics (MPs) are of increasing global concern for species inhabiting aquatic habitats. However, the mechanisms behind animal responses to MPs need comprehensive exploration. Amphibians are the most threatened vertebrate group with most species having a complex life cycle, commonly with an aquatic larval stage. Here, we investigated whether exposure to an environmentally-relevant concentration of MPs affects the growth of filter-feeding larvae of the African clawed frog (Xenopus laevis), and the consequences for their stress physiology (corticosterone (CORT) levels), or health and ageing physiology (oxidative stress and telomere length). We conducted a 3x2 experiment with three levels of fibre exposure (fibres absent -control-, and MP and cellulose fibre treatments), and two stress levels (CORT absent -control-, and CORT present simulating a stressful condition). We observed a negative impact of MP exposure on larval growth; however, this did not alter the CORT levels, oxidative stress or telomere length. Our study shows that realistic concentrations of MPs is not enough to induce major alterations on the stress or health and ageing physiology of a filter-feeding amphibian. Whether compensatory growth responses during the post-metamorphic stages could lead to detrimental effects later in life should be explored in amphibians and other organisms with complex-life cycles.

evolutionary biology↗

bioRxiv2024

Trehalose supports the growth of Aedes aegypti cells and modifies gene expression and dengue virus replication

Trehalose is a non-reducing disaccharide that is the major sugar found in insect hemolymph fluid. Trehalose provides energy, and promotes growth, metamorphosis, stress recovery, chitin synthesis, and insect flight. Trehalase is the only enzyme responsible for the hydrolysis of trehalose, which makes it an attractive molecular target. Here we show that Aedes aegypti (Aag2) cells express trehalase and that they can grow on trehalose-containing cell culture media. Trehalase activity was confirmed by treating Aag2 cells with trehalase inhibitors, which inhibited conversion of trehalose to glucose and reduced cell proliferation. Cell entry of a fluorescent trehalose probe was dependent on trehalose concentration, suggesting that trehalose moves across the cell membrane via passive transport. Culturing Aag2 cells with trehalose-containing cell culture media led to significant changes in gene expression, intracellular lipids, and dengue virus replication and specific infectivity, and increased their susceptibility to trehalase inhibitors. These data describe an in vitro model that can be used to rapidly screen novel trehalase inhibitors and probes and underscores the importance of trehalose metabolism in Ae. aegypti physiology and transmission of a mosquito-borne virus.

microbiology↗

bioRxiv2024

Imprinting and DNA methylation in water lily endosperm: implications for seed evolution

Endosperm is a key evolutionary innovation associated with the origin of angiosperms (flowering plants). This altruistic seed tissue supports the growth and development of the embryo by mediating the relationship of the mother plant as a nutrient source to the compatriot embryo as a nutrient sink. The endosperm is the primary site of gene imprinting in plants (where expression of an allele in offspring depends on which parent it was inherited from) and of parent-specific epigenetic modifications like DNA methylation, which are differentially patterned during male and female gamete development. Experimental results from a phylogenetically-wide array of monocot and eudicot plants suggest these parent-of-origin effects are a common feature across angiosperms. However, information about genetic imprinting and epigenetic modifications in seeds of angiosperm lineages whose origins predate the monocot-eudicot divergence (such as Nymphaeales, water lilies) is extremely limited. Additionally, Nymphaeales are an intriguing lineage in which to investigate seed genetic and epigenetic phenomena, as they are characterized by diploid endosperm and a maternal storage tissue (perisperm), both of which are unusual across angiosperm diversity. Here, we examined DNA methylation and genetic imprinting using two reproductively compatible water lily sister-species, Nymphaea thermarum and N. dimorpha. Our results suggest that maternally-expressed imprinted genes and differential DNA methylation of maternally and paternally inherited endosperm genomes are an ancestral condition for endosperm, while other seed characters like seed provisioning strategies, endosperm ploidy, and paternally-expressed imprinted genes might have evolved as coinciding, opposing strategies in the evolutionary dialogue over parental control of offspring development.

evolutionary biology↗

bioRxiv2019

RNA binding kinase UHMK1 regulates therapy induced metabolic adaptation in BRAFV600 melanoma

Despite the success of therapies targeting oncogenes in cancer, clinical outcomes are limited by a residual disease that results in relapse. This residual disease is characterized by drug-induced adaptation, that in melanoma includes altered metabolism. Here, we examined how targeted therapy reprograms metabolism in BRAF-mutant melanoma cells using a genome-wide RNAi screen and global gene expression profiling. This systematic approach revealed post-transcriptional regulation of metabolism following BRAF inhibition, involving selective mRNA transport and translation. As proof of concept we demonstrate the RNA binding kinase UHMK1 interacts with mRNAs that encode metabolic proteins and selectively controls their transport and translation during adaptation to BRAF targeted therapy. Inactivation of UHMK1 improves metabolic response to BRAF targeted therapy and delays resistance to BRAF and MEK combination therapy in vivo. Our data support a model wherein post-transcriptional gene expression pathways regulate metabolic adaptation underpinning targeted therapy response and suggest inactivation of these pathways may delay disease relapse.

cancer biology↗

bioRxiv2019

Slide-seq: A Scalable Technology for Measuring Genome-Wide Expression at High Spatial Resolution

The spatial organization of cells in tissue has a profound influence on their function, yet a high-throughput, genome-wide readout of gene expression with cellular resolution is lacking. Here, we introduce Slide-seq, a highly scalable method that enables facile generation of large volumes of unbiased spatial transcriptomes with 10 {micro}m spatial resolution, comparable to the size of individual cells. In Slide-seq, RNA is transferred from freshly frozen tissue sections onto a surface covered in DNA-barcoded beads with known positions, allowing the spatial locations of the RNA to be inferred by sequencing. To demonstrate Slide-seqs utility, we localized cell types identified by large-scale scRNA-seq datasets within the cerebellum and hippocampus. We next systematically characterized spatial gene expression patterns in the Purkinje layer of mouse cerebellum, identifying new axes of variation across Purkinje cell compartments. Finally, we used Slide-seq to define the temporal evolution of cell-type-specific responses in a mouse model of traumatic brain injury. Slide-seq will accelerate biological discovery by enabling routine, high-resolution spatial mapping of gene expression. One Sentence SummarySlide-seq measures genome-wide expression in complex tissues at 10-micron resolution.

genomics↗