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bioRxiv2026

A nuclear targeting approach enables efficient transgenesis in the milkweed bug Oncopeltus fasciatus

Insects show extreme diversity and have long intrigued biologists. Recent technological advancements, such as gene editing and transgenesis, should in principle enable the use of almost any insect species for biological research. However, in practice, species-specific challenges remain and conditions must be optimized carefully. Here, using the milkweed bug Oncopeltus fasciatus, we first generate a useful eye- and body-color mutant strain by using CRISPR/Cas9-mediated genome editing. Then we use this strain to develop an efficient piggyBac-mediated transgenesis system using a nuclear targeting approach. We show that incorporating 1x and 3x nuclear localization signals (NLS) into piggyBac mRNA substantially enhances overall transformation efficiency in O. fasciatus. Taking advantage of both the useful mutant strain and the efficient transgenesis system, we successfully integrated multiple expression cassettes ranging from 1.8 to 7.2 kb, including attP strains for phiC31-mediated site-specific integration and histone-labelled strains for live fluorescence imaging. We further provide evidence that the Q system, a binary expression system, is functional in this species, paving the way for future sophisticated genetic manipulations including functional assays for cis-regulatory elements. Together, our results not only expand the genetic toolkit of O. fasciatus as a comparative model insect, but also provide a practical framework for developing efficient transgenesis in other non-traditional model organisms.

developmental biology↗
bioRxiv2024

Feeding a rich diet supplemented with the translation inhibitor cycloheximide decreases lifespan and ovary size in Drosophila

Drosophila oogenesis has long been an important model for understanding myriad cellular processes controlling development, RNA biology, and patterning. Flies are easily fed drugs to disrupt various molecular pathways. However, this is often done under poor nutrient conditions that adversely affect oogenesis, thus making analysis challenging. Cycloheximide is a widely used compound that binds to and stalls the ribosome, therefore reducing protein synthesis. Since egg production is a highly nutrient-dependent process, we developed a method to feed female Drosophila a rich diet of yeast paste supplemented with cycloheximide to better determine the effect of cycloheximide treatment on oogenesis. We find flies readily consume cycloheximide-supplemented yeast paste. Males and females have reduced lifespans when maintained on cycloheximide, with males exhibiting a dose-dependent decrease. While females did not exhibit decreased egg-laying, their ovaries were smaller and the number of progeny reduced, indicating substandard egg quality. Finally, females fed cycloheximide have disrupted oogenesis, with smaller ovaries, missing ovariole stages, and an increase in apoptotic follicles. Together, these data support that reduced protein synthesis adversely affects oogenesis with a rich diet that provides optimal nutrient conditions. In addition, this method could be used more broadly to test the effect of other drugs on Drosophila oogenesis without the confounding effects caused by poor nutrition.

developmental biology↗
bioRxiv2018

EGFR confers exquisite specificity of Wnt9a-Fzd9b signaling in hematopoietic stem cell development

The mechanisms of Wnt-Frizzled (Fzd) signaling selectivity and their biological implications remain unclear. We demonstrate for the first time that the epidermal growth factor receptor (EGFR) is required as a co-factor for Wnt signaling. Using genetic studies in zebrafish, paired with in vitro cell biology and biochemistry, we have determined that Fzd9b signals specifically with Wnt9a in vivo and in vitro to elicit {beta}-catenin dependent Wnt signals that regulate hematopoietic stem and progenitor cell (HSPC) development in the dorsal aorta. This requirement is conserved in the derivation of HSPCs from human embryonic stem cells. Wnt9a-Fzd9b specificity requires two intracellular domains in Fzd9b, which interact with EGFR as a required co-factor to promote signal transduction. EGFR phosphorylates one tyrosine residue on Fzd9b, a requirement for the Wnt signal. These findings indicate that Wnt signaling interactions can be exquisitely specific and inform protocols for derivation of HSPCs in vitro.\n\nHighlightsO_LIAn in vitro signaling screen identifies Fzd9b as a Wnt9a-specific receptor.\nC_LIO_LIFzd9b and Wnt9a regulate hematopoietic stem cell development as a cognate pair.\nC_LIO_LIWNT9A and FZD9 are required for HSPC derivation from human pluripotent cells in vitro.\nC_LIO_LIEGFR confers specificity to Wnt9a-Fzd9b signaling in zebrafish and human cells.\nC_LI

developmental biology↗
bioRxiv2021

Stretch-induced endogenous electric fields drive neural crest directed collective cell migration in vivo

Directed collective cell migration (dCCM) is essential for morphogenesis1, 2. Cell clusters migrate in inherently complex in vivo environments composed of chemical, electrical, mechanical as well as topological features. While these environmental factors have been shown to allow dCCM in vitro, our understanding of dCCM in vivo is mostly limited to chemical guidance3. Thus, despite its wide biological relevance, the mechanisms that guide dCCM in vivo remain unclear. To address this, we study endogenous electric fields in relation to the migratory environment of the Xenopus laevis cephalic neural crest, an embryonic cell population that collectively and directionally migrates in vivo4, and whose migratory mode has been linked to cancer invasion and metastasis5. Combining bioelectrical, biomechanical and molecular tools, we show that endogenous electric fields drive neural crest dCCM via electrotaxis in vivo. Moreover, we identify the voltage-sensitive phosphatase 1 (Vsp1) as a key component of the molecular mechanism used by neural crest cells to transduce electric fields into a directional cue in vivo. Furthermore, Vsp1 function is specifically required for electrotaxis, being dispensable for cell motility and chemotaxis. Finally, we reveal that endogenous electric fields are mechanoelectrically established. Mechanistically, convergent extension movements of the neural fold generate membrane tension, which in turn opens stretch-activated channels to mobilise the ions required to fuel electric fields. Overall, our results reveal a mechanism of cell guidance, where electrotaxis emerges from the mechanoelectrical and molecular interplay between neighbouring tissues. More broadly, our data contribute to validate the, otherwise understudied, functions of endogenous bioelectrical stimuli in morphogenetic processes6.

developmental biology↗
bioRxiv2022

Associations of Socioeconomic Disparities With Buccal DNA-Methylation Measures Of Biological Aging

BackgroundIndividuals who are socioeconomically disadvantaged are at increased risk for aging-related diseases and perform less well on tests of cognitive function. The Weathering Hypothesis proposes that these disparities in physical and cognitive health arise from an acceleration of biological processes of aging. Theories of how life adversity is biologically embedded identify epigenetic alterations, including DNA methylation (DNAm), as a mechanistic interface between the environment and health. Consistent with the Weathering hypothesis and theories of biological embedding, recently developed DNAm algorithms have revealed profiles reflective of more advanced aging and lower cognitive function among socioeconomically-at-risk groups. These DNAm algorithms were developed using blood-DNA, but social and behavioral science research commonly collect saliva or cheek-swab DNA. This discrepancy is a potential barrier to research to elucidate mechanisms through which socioeconomic disadvantage affects aging and cognition. We therefore tested if social gradients observed in blood-DNAm measures could be reproduced using buccal-cell DNA obtained from cheek swabs. ResultsWe analyzed three DNAm measures of biological aging and one DNAm measure of cognitive performance, all of which showed socioeconomic gradients in previous studies: the PhenoAge and GrimAge DNAm clocks, DunedinPACE, and Epigenetic-g. We first computed blood-buccal cross-tissue correlations in n=21 adults (GEO111165). Cross-tissue correlations were low-to-moderate across (r=.25 to r=.48). We next conducted analyses of socioeconomic gradients using buccal DNAm data from SOEP-G (n=1128, 57% female; age mean=42 yrs, SD=21.56, range 0-72). Associations of socioeconomic status with DNAm measures of aging were in the expected direction, but were smaller as compared to reports from blood DNAm datasets (r=-.08 to r=-.13). ConclusionsOur findings are consistent with the hypothesis that socioeconomic disadvantage is associated with DNAm indicators of worse physical and cognitive health. However, relatively low cross-tissue correlations and attenuated effect-sizes for socioeconomic gradients in buccal DNAm compared with reports from analysis of blood DNAm suggest that, in order to take full advantage of buccal-DNA samples, DNAm algorithms customized to buccal DNAm are needed.

developmental biology↗
bioRxiv2024

Effect of glucose concentration in culture medium on the human preimplantation embryo methylome

Study questionDoes glucose concentration in culture medium have an impact on the DNA methylome of the early human embryo? Summary answerGlucose concentration is associated with changes in gene expression, global DNA methylation, methylation levels at CpG islands and at key histone modifications in human blastocysts. What is known alreadyPreimplantation human embryos are highly sensitive to their local environment, and this may have long term implications for the health of the developing embryo, fetus and offspring. Glucose is a standard component of human embryo culture media, due to its importance as a nutrient. However, concentrations of glucose differ widely between different commercially available types. The present study was designed to determine whether changes in glucose concentration could influence global methylation and gene expression in the human preimplantation embryo. Study design, size, durationHuman embryos were cultured in clinically relevant concentrations of glucose and global DNA methylation analysis was performed. The effect of glucose concentration on the embryo epigenome, specifically DNA methylation, was analysed. Participants/materials, setting, methodsHuman embryos surplus to treatment requirements were donated with informed consent from several ART centres. Embryos were cultured to the blastocyst stage in Vitrolife G-TL medium, either at 0.9 mM or 3.5 mM glucose, separated via immunosurgery into Inner Cell Mass (ICM) and trophectoderm (TE) samples, and compared for both DNA methylation and gene expression. This allowed us to evaluate the association between DNA methylation and previously importantly identified biological pathways. Main results and the role of chanceThe concentration of glucose in human embryo culture medium was associated with changes in gene expression and global DNA methylation in both ICM and TE, and methylation levels at CpG islands and key histone modifications. These results are significant because glucose is a major nutrient metabolised by human embryos in culture, and yet we know relatively little of its downstream effects on the genome and epigenome. Wider implications of the findingsCommercially available embryo culture media with varying glucose levels have also been associated with altered fetal growth, birthweight and postnatal development of IVF offspring. Our findings may have important ramifications for potential clinical markers of embryo quality and pregnancy initiation, and improve understanding of the mechanisms underlying the impact of the early environment on the long term health of ART offspring. Study funding/competing interest(s)This work was funded by the National Council for Science and Technology of Mexico (CONACyT), an NIHR pre-doctoral fellowship (PCAF) to MM, the NIHR Local Comprehensive Research Network and NIHR Manchester Clinical Research Facility, the University of Manchester and Manchester University NHS Foundation Trust. None of the authors has any conflict of interest to declare.

developmental biology↗
bioRxiv2024

Open-hardware solutions for light sheet microscopy specimen chambers

Light sheet fluorescence microscopy (LSFM) is a powerful tool for imaging large three-dimensional biological samples. However, the design and fabrication of specimen chambers for these systems present significant challenges, particularly in maintaining water-tight seals, preventing contamination, and ensuring the flexibility needed for precise positioning of the objective and sample. This study introduces open-hardware solutions to address these challenges, utilising a combination of 3D printing, silicone injection moulding, and FEP-foil thermoforming. We describe the development of custom, highly flexible silicone seals and connectors through a laboratory-scale injection moulding process. These components enable precise, low-resistance movement of imaging objectives and specimen holders, which is crucial for maintaining imaging accuracy. Additionally, we introduce a novel "optical window" design that isolates the objective lens from the immersion medium, significantly reducing the risk of contamination and facilitating easy exchange of chambers and lenses without compromising sterility. The practicality of these designs is demonstrated through their application in long-term live imaging of Tribolium castaneum embryos, honey bee embryos, and human mesenchymal stem cell spheroids. By providing open-source CAD and 3D printing files, this work promotes accessibility and customization in microscopy, enabling researchers to easily replicate and adapt these solutions to their specific needs.

developmental biology↗
bioRxiv2019

Single-cell analysis of Non-CpG methylation dynamics and gene expression in human oocyte maturation

Oocyte maturation is a coordinated process that is tightly linked to reproductive potential. A better understanding of gene regulation during human oocyte maturation will not only answer an important question in biology, but also facilitate the development of in vitro maturation technology as a fertility treatment. We generated single-cell transcriptome and use previously published single-cell methylome data from human oocytes at different maturation stages to investigate how genes are regulated during oocyte maturation, focusing on the potential regulatory role of non-CG methylation. DNMT3B, a gene encoding a key non-CG methylation enzyme, is one of the 1000 genes upregulated in mature oocytes, which may be at least partially responsible for the increased non-CG methylation as oocytes mature. Non-CG differentially methylated regions (DMRs) between mature and immature oocytes have multiple binding motifs for transcription factors, some of which bind with DNMT3B and may be important regulators of oocyte maturation through non-CG methylation. Over 98% of non-CG DMRs locate in transposable elements, and these DMRs are correlated with expression changes of the nearby genes. Taken together, this data indicates that global non-CG hypermethylation during oocyte maturation may play an active role in gene expression regulation, potentially through the interaction with transcription factors.

developmental biology↗
bioRxiv2019

Efficient generation of zebrafish maternal-zygotic mutants through transplantation of ectopically induced and Cas9/gRNA targeted PGCs

The CRISPR/Cas9 technology has been widely utilized for knocking out genes involved in various biological processes in zebrafish. Despite this technology is efficient for generating different mutations, one of the main drawbacks is low survival rates during embryogenesis when knocking out some embryonic lethal genes. To overcome this problem, we developed a novel strategy using a combination of CRISPR/Cas9 mediated gene knockout with primordial germ cells (PGCs) transplantation to facilitate and speed up the process of zebrafish mutant generation, particularly for embryonic lethal genes. First, we optimized the procedure for gRNA targeted PGCs transplantation (PGCT), by increasing the efficiencies of genome mutation in PGCs and induction of PGCs fates in donor embryos for PGCT. Second, the combined CRISPR/Cas9 with PGCT was utilized for generation of maternal zygotic (MZ) mutants of tcf7l1a (essential gene for head development), pou5f3 (essential gene for zygotic genome activation) and chd (essential gene for dorsal development) at F1 generation with high efficiency. Finally, we revealed some novel phenotypes in the maternal zygotic mutant of tcf7l1a and chd, while MZtcf7l1a showed elevated neural crest development, and MZchd have stronger ventralization than its zygotic counterparts. Therefore, this study presents an efficient and powerful method for generating MZ mutants of embryonic lethal genes in zebrafish.

developmental biology↗
bioRxiv2023

The mechanical force with the physiological movement works as a biological cue in tendon development during the postnatal phase in mice

The musculoskeletal system provides structural stability and coordination to enable movement. Tendons have the essential role of efficiently transmitting force generated from muscle contraction to bone to enable ambulation. In doing so, they resist high external forces. In fact, muscle contraction during embryonic development is required to maintain tendon growth and differentiation. Nonetheless, defining the types and magnitudes of loads that act on tendons during embryonic and early postnatal periods is quite difficult. In this study, we aimed to define the physiologic limb movement and forces experienced during these stages in the murine model. We found that late-stage embryos had limited amniotic space, which attenuated limb movement. In the neonatal phase, physical ability, as measured by rollover function and locomotion, increased. These changes, which likely corresponded to increased forces applied to the tendons, corresponded with the expression of tenogenic markers during the embryo to postnatal phase. In particular, we found that the upregulation of Scx and Tnmd correlated with increased movement during the two weeks after birth. Our results help define the spatiotemporal role of mechanical force, including internal and external factors, in tendon growth and development. HighlightsO_LIAssessed limb movement in amnion. C_LIO_LISpace limitation attenuated limb movement in the late-stage embryos. C_LIO_LIDefined the mechanical force from the limbs physiological environment. C_LIO_LIScx and Tnmd were upregulated synchronically with rollover function and locomotion. C_LIO_LIMechanical forces may work as the cue of tendon development C_LI

developmental biology↗
bioRxiv2025

CreER activation transiently impairs angiogenesis by slowing endothelial proliferation

Tamoxifen-inducible gene targeting in mice with estrogen receptor-dependent Cre (CreER) recombinase has enormously advanced vascular biology research. However, CreER activation under the control of vascular endothelial promoters is now recognized to cause off-target effects that impair angiogenesis in the widely used perinatal mouse retina model. Although ubiquitously expressed CreER is also used to study retinal angiogenesis, it remains unknown whether it causes similar or more severe off-target effects compared to endothelial-selective CreER activation. Moreover, the cellular processes disrupted by CreER-induced endothelial toxicity remain to be identified. Here, we demonstrate that ubiquitous CreER activation in postnatal mice decreases body growth throughout the period of retinal angiogenesis and impairs retinal angiogenesis in a tamoxifen dose-dependent manner. We further show that CreER activation from both endothelial and ubiquitously expressed CreER transgenes suppresses endothelial cell proliferation downstream of p21/CDKNA1 upregulation. By contrast, we find that p21/CDKNA1 is not upregulated in quiescent adult retinal endothelium, and that CreER-induced postnatal angiogenesis defects recover two weeks after tamoxifen discontinuation. Altogether, our findings indicate that ubiquitous promoters should be avoided for CreER expression when studying endothelial genes, and that short-term retinal angiogenesis studies require endothelial CreER toxicity controls that may be less critical for adult vascular studies.

developmental biology↗
bioRxiv2020

Zebrafish Kit ligands cooperate with erythropoietin to promote erythroid cell expansion

Kit ligand (Kitlg) is pleiotropic cytokine with a prominent role in vertebrate erythropoiesis. Although the role of Kitlg in this process has not yet been reported in Danio rerio (zebrafish), in the present study, we show that its function is evolutionary conserved. Zebrafish possess two copies of Kitlg genes (Kitlga and Kitlgb) due to whole genome duplication. To determine the role of each ligand in zebrafish, we performed a series of ex vivo and in vivo gain- and loss-of-function experiments. First, we tested the biological activity of recombinant Kitlg proteins in suspension culture from zebrafish whole kidney marrow and we demonstrate that Kitlga is necessary for expansion of erythroid progenitors ex vivo. To further address the role of kitlga and kitlgb in hematopoietic development in vivo, we performed gain-of-function experiments in zebrafish embryos, showing that both ligands cooperate with erythropoietin (Epo) to promote erythroid cell expansion. Finally, using the kita mutant (kitab5/b5 or sparse), we show that Kita receptor is crucial for Kitlga/b cooperation with Epo in erythroid cells. In summary, using optimized suspension culture conditions with recombinant cytokines (Epo, Kitlga), we are reporting for the first time ex vivo suspension cultures of zebrafish hematopoietic progenitor cells, which can serve as an indispensable tool to study normal and aberrant hematopoiesis in zebrafish. Furthermore, we conclude that although partial functional diversification of Kit ligands has been described in other processes, in erythroid development, both paralogs play a similar role and their function is evolutionary conserved. Key points: O_LIKit signaling contributes to erythroid cell development and is conserved from fish to man C_LIO_LIEx vivo expansion and self-renewal of zebrafish erythroid progenitors requires addition of recombinant Kitlga C_LI

developmental biology↗
bioRxiv2025

Mechanical control of histone serotonylation initiates neural crest migration in vivo

Collective cell migration (CCM) is pivotal in several biological contexts, and posttranslational modifications of histones are essential to initiate this process1-3. Here, we show that a recently discovered chromatin mark, termed histone serotonylation4, is involved in the collective migration of cranial neural crest cells - an embryonic multipotent stem cell population5. Our in vivo data reveal that histone serotonylation appears in neural crest cells just before they start migrating and that its occurrence is essential to initiate their CCM. Surprisingly, we found that stiffening of the neural crest migratory substrate, the mesoderm, induces histone serotonylation by promoting nuclear translocation of transglutaminase 2 (Tgm2), the enzyme responsible for adding serotonin to histones4. Moreover, mechanical and molecular perturbations demonstrate that mechanical shuttling of Tgm2 into the nucleus, with concomitant increases in histone serotonylation, are both required and sufficient to allow CCM in vivo. Furthermore, integrated chromatin immunoprecipitation and RNA sequencing analyses uncover a transcriptional module, which is enabled by histone serotonylation in response to mesoderm stiffening. Altogether, our results provide in vivo evidence showing that tissue stiffening leads to increased levels of histone serotonylation to reinforce permissive patterns of gene expression, supporting the switch from non-migratory to migratory cell states.

developmental biology↗
bioRxiv2025

Epigenetic Coalitions Couple Tissue Growth to Generate Periodic Colour Patterns in Birds

Periodic patterning is fundamental to biological organization. In birds, colour stripes and spots on growing embryonic surface and elongating feather filaments provide a unique system to study continuous periodic patterning in expanding domains. Agouti-signaling protein (ASIP) directly reports epigenomic activity during colour patterning. Using a neural-network-like architecture, we show that ASIPs cis-regulatory landscape functions as hidden layers, integrating morphogen feedback, chromatin topology, and tissue geometry to generate discrete colour outputs. Single-nucleus multiome and Micro-C uncover stage- and context-specific enhancer-silencer coalitions. Epidermal Wnt ligands activate ASIP while inducing Wnt inhibitors in fibroblasts, forming a negative-feedback loop coupling periodic patterning to domain expansion. Comparative cross-tissue and cross-species analyses define cis-regulatory modules comprising an epigenetic grammar; functional assays highlight retrotransposon co-option expanding ASIPs cis-regulatory repertoire, potentially contributing to colour pattern evolution. Together, these findings motivate a Turing-principle-based communication model: ASIP reflects epigenetic coalitions shifting to drive diverse, environmentally tunable colour motifs for adaptation.

developmental biology↗
bioRxiv2025

An optogenetic toolkit for robust activation of FGF, BMP, and Nodal signaling in zebrafish

Cell signaling regulates a wide range of biological processes including development, homeostasis, and disease. Accessible technologies to precisely manipulate signaling have important applications in basic and translational research. Here, we present an optogenetic toolkit for signaling manipulation in zebrafish embryos. We introduce a zebrafish-optimized optogenetic FGF signaling activator and a single-transcript Nodal signaling activator, and assess them together with a previously established BMP signaling activator. We thoroughly characterize this suite of tools and demonstrate light-dependent spatiotemporal control of signaling in vivo. In response to [~]455 nm (blue) light, zebrafish receptor kinase domains fused to blue light-dimerizing LOV domains enable robust signaling activation with minimal inadvertent activity in the dark or at wavelengths over 495 nm. Each optogenetic tool initiates pathway-specific signaling and activates known target genes. Signaling is activated with rapid on/off kinetics, and activation strength can be tuned by adjusting light irradiance. Finally, we demonstrate spatially localized signaling activation in vivo. Together, our results establish this optogenetic toolkit as a potent experimental platform and provide guidelines for rapid, direct, and adjustable activation of FGF, BMP, and Nodal signaling in zebrafish embryos.

developmental biology↗
bioRxiv2025

Neural Synchrony in Parent-Child Dyads: Profiles Associated with Interparental Conflict and Internalizing Symptoms

Interparental conflict and parental stress are well-established risk factors for child psychopathology, including elevated internalizing and externalizing symptoms. From a family systems framework, these stressors may spill over into the parent-child relationship, undermining emotional attachment and co-regulation processes central to childrens mental health. Neural synchrony, defined as the dynamic, mutual alignment of brain activity between a parent and child, offers a biological index of these dyadic processes. Using functional near-infrared spectroscopy, researchers have shown that greater neural synchrony (NS) in prefrontal brain regions is associated with more attuned caregiving and positive child adjustment. Yet, NS is not uniform; it varies across dyads in pattern and regional distribution, potentially reflecting differences in relational dynamics, regulation, or stress exposure. To capture this heterogeneity, we used latent profile analysis to identify distinct synchrony patterns along the right and left ventrolateral and dorsolateral prefrontal cortices during the DB-DOS:Biosynch - a mild stress, three-context task. We further examined whether interparental conflict and perceived parental stress predicted profile membership, and whether childrens internalizing and externalizing behaviors differed by profile. Among 194 dyads, two profiles emerged: lower baseline synchrony (LB; n = 132) and higher baseline synchrony (HB; n = 62). Greater interparental conflict reduced the odds of membership in HB, while parental stress was not predictive of profile membership. Additionally, children in LB exhibited higher levels of internalizing behaviors compared to HB, with no group differences observed for externalizing behaviors. These findings underscore the value of capturing synchrony heterogeneity in understanding family stress and child psychopathology.

developmental biology↗
bioRxiv2020

Embryogenesis, polyembryony, and settlement in the gorgonian Plexaura homomalla

Understanding the ontogeny and reproductive biology of reef-building organisms can shed light on patterns of population biology and community structure. This knowledge is particularly important for Caribbean octocorals, which seem to be more resilient to long-term environmental change than scleractinian corals and provide some of the same ecological services. We monitored the development of the black sea rod Plexaura homomalla, a common, widely distributed octocoral on shallow Caribbean reefs, from eggs to 3-polyp colonies over the course of 73 days. In aquaria on St John, U.S. Virgin Islands, gametes were released in spawning events three to six days after the July full moon. Cleavage started 3 hours after fertilization and was holoblastic, equal, and radial. Embryos were positively buoyant until becoming planulae. Planulae were competent after 4 days. Symbiodiniaceae began infecting polyps at around 8 days post fertilization. Development was typical for Caribbean octocorals, except for the occurrence of a novel form of asexual reproduction in octocorals: polyembryony. Fragmentation of embryos during development may represent a temporally varied tradeoff between number and size of propagules, in which large eggs have higher fertilization rates followed by polyembryony, which maximizes the number of surviving recruits by generating more, albeit smaller, larvae. Polyembryony may contribute to the success of some gorgonians on Caribbean reefs as other anthozoans are in decline.

developmental biology↗
bioRxiv2022

GPCR Signaling Promotes a Stress-induced Genetic Program for Phenoptosis in C. elegans

How an organism dies is a fundamental yet poorly understood question in biology. An organism can die of many causes, including stress-induced phenoptosis, also defined as organismic death that is regulated by its genome-encoded programs. The mechanism of stress-induced phenoptosis is still largely unknown. Here we show that transient but severe freezing-thaw stress (FTS) in C. elegans induces rapid and robust phenoptosis that is regulated by G-protein coupled receptor (GPCR) signaling. RNAi screens identify the GPCR-encoding fshr-1 in mediating transcriptional responses to FTS. FSHR-1 increases ligand interaction upon FTS and activates a cyclic AMP-PKA cascade leading to a genetic program to promote organismic death under severe stress. FSHR-1/GPCR signaling up-regulates the bZIP-type transcription factor ZIP-10, linking FTS to expression of genes involved in lipid remodeling, proteostasis and aging. A mathematical model suggests that genes may promote organismic death under severe stress conditions, potentially benefiting growth of the clonal population with individuals less stressed and more reproductively privileged. Our studies reveal roles of FSHR-1/GPCR-mediated signaling in stress-induced gene expression and phenoptosis in C. elegans, providing empirical new insights into mechanisms of stress-induced phenoptosis with evolutionary implications.

developmental biology↗