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Martel, C.

Publications and source records attributed to Martel, C..

8 recordsLinked to original sources
bioRxiv2026

Decoupling Transcription from Cell Fate Preserves Germ Cell Totipotency

Only germ cells can give rise to a totipotent embryo, yet a conserved transcriptional program for germ cell identity remains elusive. Profiling Drosophila primordial germ cells (PGCs) across embryogenesis, we find that nascent PGCs are not silent, as previously thought, but instead transcribe the same totipotency program as the early embryo, reflecting an open chromatin state. This chromatin state, established by the pioneer factor Zelda, persists in PGCs throughout development. The associated transcriptional program normally drives somatic differentiation, but in PGCs the conserved RNA-regulator Nanos represses its translation, leaving germline chromatin uncommitted. Cells that fail to establish the totipotent state die before reaching the gonad. Thus, germ cells preserve developmental potential not by restricting transcription, but by preventing transcripts from determining cell fate.

developmental biology↗
bioRxiv2025

Two hundred years of changes in orchid pollination revealed using herbarium specimens

Orchids are one of the most diverse plant families and are renowned for their highly specialised interactions with pollinators. Despite growing evidence of orchid population decline, pollinator decline and rising concerns for orchid reproductive success, long-term changes remain poorly understood. To address this gap, we analysed changes in pollinarium removal, as a proxy for pollination success, in herbarium specimens of three species-rich orchid genera (Disa, Oncidium and Ophrys) hosted at the Royal Botanic Gardens, Kew, which has a rich and diverse orchid collection spanning the past two centuries. The selected genera occur in different major regions (subtropical and tropical Africa, predominantly temperate Europe, and tropical America, respectively). Our analysis reveals that pollinarium removal declined significantly in Disa and Oncidium, particularly among species with deceptive strategies or specialised pollination mechanisms. In contrast, Ophrys showed a significant increase, driven by Apidae-pollinated species, whereas pollinarium removal for Andrenidae-pollinated species declined over time. These contrasting findings reflect the role of orchid identity, pollinator availability and pollination strategy in shaping reproductive success under anthropogenic change. Overall, this study demonstrates the power of herbarium specimens to reveal long-term ecological changes, providing unique insights into the response of specific plant-pollinator interactions to increasing anthropogenic pressure.

plant biology↗
bioRxiv2024

Circular RNAs exhibit exceptional stability in the aging brain and serve as reliable age and experience indicators

Circular RNAs (circRNAs) comprise a large class of stable RNAs produced through backsplicing. While circRNAs have been shown to be very stable in cell culture, it is unknown how stable they are in vivo. Interestingly, studies across various animal systems demonstrated that circRNAs levels increase with age in neural tissue. However, the underlying reasons for this age-related accumulation are still unclear. To address these questions, we profiled circRNAs from fly heads at six timepoints across their lifespan. We found that circRNA levels increase linearly with age, independent of changes in mRNA levels, overall transcription, intron retention, or host genes splicing. This indicates that the age-related accumulation is attributed to their extraordinary stability in neural tissue rather than changes in biosynthesis. Furthermore, exposure to environmental stimuli like different temperatures, resulted in the increase but not decrease of circRNAs subsets, further confirming their stability in vivo. This exceptional stability implies that circRNAs can serve as markers of environmental experience. Indeed, flies subjected to a ten-day regimen at 29{degrees}C exhibit higher levels of specific brain circRNAs even six weeks after returning to standard conditions, indicating that circRNAs can reveal past environmental stimuli. Additionally, circRNA half-life measurements revealed values exceeding 20 days, with some showing no degradation over the animals lifetime. These findings demonstrate the extreme stability of circRNAs in vivo and their use as markers for aging, stress and life experiences.

neuroscience↗
bioRxiv2024

Sequential emergence and contraction of epithelial subtypes in the prenatal human choroid plexus revealed by a stem cell model

Despite the major roles of choroid plexus epithelial cells (CPECs) in brain homeostasis and repair, their developmental lineage and diversity remain undefined. In simplified differentiations from human pluripotent stem cells, derived CPECs (dCPECs) displayed canonical properties and dynamic multiciliated phenotypes that interacted with A{beta} uptake. Single dCPEC transcriptomes over time correlated well with human organoid and fetal CPECs, while pseudotemporal and cell cycle analyses highlighted the direct CPEC origin from neuroepithelial cells. In addition, time series analyses defined metabolic (type 1) and ciliogenic dCPECs (type 2) at early timepoints, followed by type 1 diversification into anabolic-secretory (type 1a) and catabolic-absorptive subtypes (type 1b) as type 2 cells contracted. These temporal patterns were then confirmed in independent derivations and mapped to prenatal stages using human tissues. In addition to defining the prenatal lineage of human CPECs, these findings suggest new dynamic models of ChP support for the developing human brain.

neuroscience↗
bioRxiv2023

Patterns and drivers of pollen co-transport networks vary across pollinator groups

Pollen transport is an understudied process with consequences for plant reproductive success and floral evolution. Recently, pollinator bodies have been described as pollen competition arenas, with implications for plant community assembly. However, the identity, strength, and diversity of pollen competitive interactions and how they vary across pollinator groups is unknown. Evaluating patterns and drivers of the pollen competition landscape across different pollinator groups is central to further our understanding of plant coexistence mechanisms. Here, we integrate information on insect pollen loads with network analyses to uncover novel pollen co-transport networks and how these vary across pollinators. We evaluate differences in pollen load size, diversity and their phenological and phylogenetic attributes among insect groups and how these relate to body size and sex. Pollen co-transport networks revealed differences in the number and identity of competitors that pollen species encounter across pollinator groups. These networks were highly modular, with groups of pollen species interacting more often on pollinator bodies. Pollen load size and richness were shaped by bee size and sex. Sex also influenced the pollen phylogenetical diversity. Pollinators can impose vastly different competitive landscapes during pollen transport, with so far unknown consequences for plant reproductive success, floral evolution and community assembly.

ecology↗
bioRxiv2022

Use of Solentim verified in-situ plate seeding (VIPSTM) enhances single-cell cloning efficiency

The primary goal in cell line development is to establish high-producer recombinant cell line(s) of single-cell origin. Traditionally, these cell lines are developed using limiting dilution cloning (LDC) method of single cell isolation, a rate-limiting, lengthy and labor-intensive process. The Verified-In-Situ-Plate-Seeding (VIPS) is an automated single-cell seeding and imaging equipment designed to accelerate cell line development workflow. In this study, VIPS was tested for efficiency and accuracy of single cell seeding in parallel with limiting dilution cloning (LDC). Three Chinese hamster ovary (CHO) derived cell lines with known clonal properties were tested under six different growth conditions (three growth media and two different kinds of microplates). Data showed VIPS and limiting dilution (LDC) have comparable cloning efficiency when CHO-M cells were tested. By contrast, the Verified In-Situ Plate Seeding (VIPS) produced 6-8-fold more clones of single-cell origin than LDC when CHO-K1 or CHO-S cells were tested. Moreover, the verified In-Situ Plate Seeding (VIPS) correctly identified single-cell and multiple-cells seeded wells with 65-72% and 52-81% accuracy, respectively. Taken together, the high throughput imaging and single-cell seeding capabilities of VIPS outperformed the rate-limiting LDC method and, therefore, has the potential to accelerate cell line development workflow.

cell biology↗
bioRxiv2021

Gender identity and sexual experience affect mating behaviour and chemical profile in the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Alphitobius diaperinus (Coleoptera: Tenebrionidae), the lesser mealworm, is one of the most significant pests of the poultry industry worldwide. These insects cause structural damage in poultry houses and transmit several diseases, impacting chickens productivity and rearing costs. Although semiochemicals may offer alternative insect pest management strategies, basic information regarding pheromone identity and their role on the behavioural ecology according to their circadian pattern of sexual behaviour of A. diaperinus is essentially lacking. This study is aimed to analyse the relation of gender identity and sexual experience of adults of A. diaperinus on their mating behaviour and whether this response is related to their CHC profiles secreted. The following steps were taken to achieve the studys goal. First, the circadian pattern of their sexual activity was observed in newly emerged pairs for at least twenty-one days (virgin adults) and experienced adults collected from the field to identify a difference based on their sexual experience and achieve the optimal mating season to develop the following assays. Subsequently, Y-tube olfactometer bioassays were conducted to evaluate their odour bouquet attraction based on gender and sexual experience. Additionally, mating behaviour bioassays were conducted to evaluate the two factor effects. Finally, cuticular analysis was performed using gas chromatography-mass spectrometry to evaluate possible chemical differences based on the two factors. With statistical and multivariate analysis, we found that behavioural, mating and chemical responses are different based on their sexual experience. The mating sequences were described into precopulatory, copulatory and postcopulatory phases. This finding gives us a deeper understanding of the sexual communication during mating. In summary, our findings provide new insights into the mating system and chemical ecology of A. diaperinus. The results presented here may serve as a base for further studies to develop strategies for managing this pest.

ecology↗