Search Results (97)

Insect metamorphosis is a complex developmental process regulated by hormonal signaling and gene transcription. To elucidate its transcriptional regulatory mechanisms, we examined chromatin accessibility dynamics during metamorphosis in two holometabolous insects, Harmonia axyridis and Drosophila melanogaster, using ATAC-seq. Our analysis revealed distinct stage-specific chromatin accessibility patterns, with peak accessibility during the prepupal stage in H. axyridis and the wandering larval to prepupal transition in D. melanogaster. Through analysis of differential accessibility regions (DARs), we identified enrichment of metamorphosis-related processes including cell morphogenesis, tissue remodeling, and hormone signaling pathways via Gene Ontology and KEGG pathway analyses. Integration of chromatin accessibility with gene expression data revealed 608 conserved genes exhibiting coordinated accessibility and expression changes across both species. Additionally, we constructed a regulatory network centered around four key transcription factors (dsx, E93, REPTOR, and Sox14) that form core regulatory modules controlling metamorphosis. This study provides novel insights into the epigenetic landscape of insect metamorphosis and establishes a foundation for understanding the transcriptional regulatory mechanisms governing this critical developmental process. Full article

Greater amberjack (Seriola dumerili) shows potential for Mediterranean aquaculture due to its swift growth, consumer appeal, and commercial value. However, challenges in juvenile production, such as growth dispersion and unsynchronized development, impede further expansion. This study explores the impact of rearing temperature and live feed types on early white muscle development in greater amberjack larvae. Findings reveal substantial effects of temperature and diet on larval development, highlighting that the combination of 24 °C and a copepod + rotifer co-feeding scheme resulted in the highest axial growth rate, whereas rotifer-fed larvae at 20 °C exhibited a slower pace. Incorporating both histological and gene expression analyses, the study underscores temperature’s significant influence on white muscle development. Among larvae reared at 24 °C, the two live feed types led to phenotypic variations at metamorphosis, with rotifers supporting longer larvae featuring a smaller total cross-sectional area compared to copepods. Gene expression analysis indicates heightened mylpfb and myog expression at 24 °C during early larval stages, suggesting increased hyperplasia and myoblast differentiation. This study highlights the necessity of considering both temperature and feed type in larval rearing practices for optimal muscle development, and further research exploring combined diets during rearing could offer insights to enhance amberjack aquaculture sustainability. Full article

The Spodoptera litura, a Lepidopteran pest known for its high fecundity, undergoes a complete metamorphosis, including a distinctive process during which the male testes fuse from two separate organs into a single entity, significantly enhancing its fertility. To elucidate the molecular mechanisms underlying this testicular fusion, this study employed an integrated multi-omics approach to investigate concurrent changes at the transcriptomic and proteomic levels. We identified a series of synchronized alterations on the peritestic larval membrane, including heme binding, peptidase activity, hydrolase activity, metal ion transport, redox reactions, and chitin metabolism, all of which are substantially enriched at specific temporal points during testicular fusion. Nine genes/proteins co-expressed at the mRNA and protein levels were selected for targeted quantitative proteomics (PRM) and quantitative PCR (qPCR) validation, leading to the identification of five genes potentially involved in the testicular fusion process: Sl3030, ARCP, PSLRE, Obstructor-E, and Osris9B. Notably, the gene Sl3030, once knocked out, not only disrupted the normal fusion process but also resulted in reduced testis size, thickened peritestic membranes, and abnormal sperm development. Transcriptomic sequencing of the Sl3030 knockout mutant revealed its primary influence on the fusion process by affecting the assembly of the microtubule system and cytoskeleton. This research, for the first time, provides a multi-omics perspective on the response of key signaling pathways and molecular changes during the testicular fusion of S. litura and validates the role of the previously uncharacterized gene Sl3030 in this process, offering valuable insights into the complex mechanisms of testicular fusion in this species. Full article

This study investigates the synergistic effects of integrating ozone nanobubbles (generated via a pure oxygen-fed reactor with nanobubble-diffusing air stones) and biofloc technology (BFT) on water quality optimization, pathogenic load reduction, and growth performance enhancement in Pacific white shrimp (Penaeus vannamei) prenursery aquaculture systems. Four treatments were tested: a clear water control (CW), ozonated clear water (CW + O), biofloc (FLOC), and biofloc with ozone (FLOC + O). The FLOC + O group significantly improved water quality, reducing total ammonia nitrogen (TAN) by 61%, nitrite nitrogen (NO₂⁻-N) by 78% compared to CW, and total suspended solids (TSS) by 21% compared to FLOC (p = 0.0015). Ozone application (maintained above 0.3 mg/L, 15 min/day) demonstrated robust pathogen suppression, achieving a sharp reduction in Muscle Necrosis Virus (MNV), a 99.5% inhibition of Vibrio spp. (from 228,885 to 107 CFU/mL), and the clearance of Epistylis spp., as determined via optical microscope. These enhancements directly translated to superior biological outcomes, with the FLOC + O group exhibiting an 82% survival rate (vs. 40% in CW) and 13% higher final body weight (11.65 mg vs. 10.32 mg in CW). The integration of ozone and BFT also accelerated larval development and improved the Zoea II to Mysis I metamorphosis success rate. By maintaining stable microbial communities and reducing organic waste, the combined system lowered the water exchange frequency by 40% and eliminated the need for prophylactic antibiotics. These results demonstrate that ozone–BFT integration effectively addresses key challenges in shrimp prenursery—enhancing disease resistance, optimizing water conditions, and improving growth efficiency. The technology offers a sustainable strategy for the intensive prenursery of Pacific white shrimp, balancing ecological resilience with production scalability. Full article

Animals often regulate their nutrient intake according to their physiological needs. There is evidence that different traits require specific nutrient blends, and that animals cannot always maximize all traits with a single diet (“nutritional trade-offs”). However, we still do not have a clear understanding of which traits might be involved in nutritional trade-offs. I compiled data from the Geometric Framework of Nutrition literature on the ratio of proteins and carbohydrates that maximize (best PC ratios) or minimize (worst PC ratios) several larval and adult traits in Drosophila melanogaster. Best and worst PC ratios clustered into three regions in the protein-carbohydrate nutrient space: (1) Low PC ratios (1:8 or higher) are best for lifespan but worst for growth or reproductive traits; (2) High PC ratios (1:1 or lower) are best for adult body mass, male reproduction, and larval developmental time but worst for lifespan; and (3) Intermediate PC ratios (<1:1 and >1:8) are best for female lifetime egg production, female reproductive rate, and larval survival. These findings support lifespan–reproduction nutritional trade-offs, highlight the potential for metamorphosis to solve nutritional trade-offs across life stages, and underscore the potential for intralocus sexual conflict to emerge over the expression of metabolic genes. Full article

Metamorphosis is a common developmental process in invertebrate development. It is essential for the degeneration of larval organs, formation of adult organs, and adaptation transformation of the living environment. However, the underlying molecular regulatory mechanism remains to be elucidated. In this study, we used tail regression of ascidian Styela clava as a model to understand the gene regulation pathway and molecular mechanism in organ metamorphosis. The TGFβ signaling pathway was screened and demonstrated to be involved in tail regression based on RNA sequencing on the different larval stages and verification with inhibitor treatment experiments. We further investigated the downstream gene network of the TGFβ signaling pathway through comparative transcriptome data analysis on the TGFβ pathway inhibition samples. Together with qRT-PCR verification, we identified four critical gene functional categories, including ion transporters/water channel, extracellular matrix structural constituent, extracellular matrix organization, and cell polarity establishment. Furthermore, a cross-species comparative analysis between Ciona robusta and S. clava was performed to understand the conservation and divergence of gene regulation in ascidians. Overall, our work identifies a crucial gene regulation pathway in ascidian tail regression and provides several potential downstream targets for understanding the molecular mechanism of larval metamorphosis. Full article

Metamorphosis is a key process in the life history of sea urchin Heliocidaris crassispina. However, the understanding of its molecular mechanisms is still lacking, especially the basic cell biology pre-metamorphosis and post-metamorphosis. Therefore, we employed single-cell RNA sequencing to delineate the cellular states of larvae and juveniles of H. crassispina. Our investigation revealed that the cell composition in sea urchins comprises six primary populations, encompassing nerve cells, skeletogenic cells, immune cells, digestive cells, germ cells, and muscle cells. Subsequently, we identified subpopulations within these cells. Our findings indicated that the larval peripheral nerves were discarded during metamorphosis. A decrease in the number of spicules was observed during this process. Additionally, we examined the differences between larval and adult pigment cells. Meanwhile, cellulase is highlighted as an essential factor for the development of competent juveniles. In summary, this study not only serves as a valuable resource for future research on sea urchins but also deepens our understanding of the intricate metamorphosis process. Full article

The present, brief review paper summarizes previous studies on a new interpretation of the presence and absence of regeneration in invertebrates and vertebrates. Broad regeneration is considered exclusive of aquatic or amphibious animals with larval stages and metamorphosis, where also a patterning process is activated for whole-body regeneration or for epimorphosis. In contrast, terrestrial invertebrates and vertebrates can only repair injury or the loss of body parts through a variable “recovery healing” of tissues, regengrow or scarring. This loss of regeneration likely derives from the change in genomes during land adaptation, which included the elimination of larval stages and intense metamorphosis. The terrestrial conditions are incompatible with the formation of embryonic organs that are necessary for broad regeneration. In fact, no embryonic organ can survive desiccation, intense UV or ROS exposition on land, and rapid reparative processes without embryonic patterning, such as recovery healing and scarring, have replaced broad regeneration in terrestrial species. The loss of regeneration in land animals likely depends on the alteration of developmental gene pathways sustaining regeneration that occurred in progenitor marine animals. Terrestrial larval stages, like those present in insects among arthropods, only metamorphose using small body regions indicated as imaginal disks, a terrestrial adaptation, not from a large restructuring process like in aquatic-related animals. These invertebrates can reform body appendages only during molting, a process indicated as regengrow, not regeneration. Most amniotes only repair injuries through scarring or a variable recovery healing, occasionally through regengrow, the contemporaneous healing in conjunction with somatic growth, forming sometimes new heteromorphic organs. Full article

The conserved role of juvenile hormone (JH) signals in preventing larvae from precocious metamorphosis has been confirmed in insects. Crustaceans have different metamorphosis types from insects; we previously proved that methyl farnesoate (MF) can prohibit larvae metamorphosis in mud crabs, but the molecular signal of this process still needs to be elucidated. In this study, methoprene-tolerant (Met) of Scylla paramamosain was obtained and characterized, which we named Sp-Met. Sp-Met contains a 3360 bp ORF that encodes 1119 amino acids; the predicted protein sequences of Sp-Met include one bHLH, two PAS domains, one PAC domain, and several long unusual Gln repeats at the C-terminal. AlphaFold2 was used to predict the 3D structure of Sp-Met and the JH binding domain of Met. Furthermore, the binding properties between Sp-Met and MF were analyzed using CD-DOCK2, revealing a putative high affinity between the receptor and ligand. In silico site-directed mutagenesis suggested that insect Mets may have evolved to exhibit a higher affinity for both MF or JH III compared to the Mets of crustaceans. In addition, we found that the expression of Sp-Met was significantly higher in female reproductive tissues than in males but lower in most of the other examined tissues. During larval development, the expression variation in Sp-Met and Sp-Kr-h1 was consistent with the immersion effect of MF. The most interesting finding is that knockdown of Sp-Met blocked the inhibitory effect of MF on metamorphosis in the fifth zoea stage and induced pre-metamorphosis phenotypes in the fourth zoea stage. The knockdown of Sp-Met significantly reduced the expression of Sp-Kr-h1 and two ecdysone signaling genes, Sp-EcR and Sp-E93. However, only the reduction in Sp-Kr-h1 could be rescued by MF treatment. In summary, this study provides the first evidence that MF inhibits crustacean larval metamorphosis through Met and that the MF-Met→Kr-h1 signal pathway is conserved in mud crabs. Additionally, the crosstalk between MF and ecdysteroid signaling may have evolved differently in mud crabs compared to insects. Full article

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = −0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa. Full article

Complete insect metamorphosis requires substantial metabolic and physiological adjustments. Although oxidative stress has been implicated in metamorphosis, details on redox metabolism during larva-to-pupa and pupa-to-adult remain scarce. This study explores redox metabolism during metamorphosis of a lepidopteran (Chlosyne lacinia), focusing on core metabolism, antioxidant systems and oxidative stress. The larva-to-pupa transition was characterized by increased lactate dehydrogenase and glutathione peroxidase (GPX) activities, coupled with depletion of reduced glutathione (GSH), high disulfide-to-total-glutathione ratio (GSSG/tGSH), and increased lipid peroxidation. As metamorphosis progressed, metabolic enzyme activities, citrate synthase and glucose 6-phosphate dehydrogenase increased, indicating heightened oxidative metabolism associated with adult development. Concurrently, GSH and GPX levels returned to larval levels and GSSG/tGSH reached its most reduced state right before adult emergence. Adult emergence was marked by a further increase in oxidative metabolism, accompanied by redox imbalance and enhanced antioxidant mechanisms. These findings highlight a fluctuation in redox balance throughout metamorphosis, with periods of oxidative eustress followed by compensatory antioxidant responses. This study is the first to identify concurrent changes in metabolism, antioxidants, redox balance and oxidative stress throughout metamorphosis. Our findings extend knowledge on redox metabolism adjustments and highlight redox adaptations and oxidative stress as natural components of complete insect metamorphosis. Full article

Spodoptera frugiperda (J.E. Smith) is a crucial agricultural pest owing to its global impact on >300 crops. Among these, the corn strain of S. frugiperda causes significant damage to maize (Zea mays L.). However, limited research exists on the influence of maize nutrients on the metamorphosis of S. frugiperda and the underlying mechanisms. In this study, the effects of different growth stages of maize leaves, namely, tender leaves (tender) and mature leaves (mature), on various aspects of larval development, including body weight, body length, developmental age, pupation rate, and eclosion rate, were investigated. Additionally, we measured the levels of 20-hydroxyecdysone (20E) and three types of juvenile hormone (JH; i.e., JH I–III) in S. frugiperda larvae fed on tender or mature. The results revealed that larvae fed on Tender exhibited significantly prolonged instar duration, reduced body weight and length, and decreased pupation and eclosion rates, with the emergence of abnormal adults. Analysis of nutritional components in maize leaves revealed significantly higher levels of amino acids, soluble sugars, and sterols in mature than in tender. Hormone analysis in S. frugiperda larvae revealed higher 20E titers in individuals feeding on mature during prepupal and pupal stages. We demonstrated the crucial role of sterols in regulating the level of 20E and pupation rate of S. frugiperda. Based on these findings, we propose that isoleucine, arginine, glutamic acid, sucrose, campesterol, and β-sitosterol serve as key nutrients influencing the development of S. frugiperda. Moreover, β-sitosterol is a significant factor influencing the interaction between maize leaves and S. frugiperda. Our research results provide a reference for the control strategy of S. frugiperda based on breeding insect-resistant varieties by altering host nutrition. Full article

Pierisin-1 was serendipitously discovered as a strong cytotoxic and apoptosis-inducing protein from pupae of the cabbage butterfly Pieris rapae against cancer cell lines. This 98-kDa protein consists of the N-terminal region (27 kDa) and C-terminal region (71 kDa), and analysis of their biological function revealed that pierisin-1 binds to cell surface glycosphingolipids on the C-terminal side, is taken up into the cell, and is cleaved to N- and C-terminal portions, where the N-terminal portion mono-ADP-ribosylates the guanine base of DNA in the presence of NAD to induce cellular genetic mutation and apoptosis. Unlike other ADP-ribosyltransferases, pieisin-1 was first found to exhibit DNA mono-ADP-ribosylating activity and show anti-cancer activity in vitro and in vivo against various cancer cell lines. Pierisin-1 was most abundantly produced during the transition from the final larval stage to the pupal stage of the cabbage butterfly, and this production was regulated by ecdysteroid hormones. This suggests that pierisn-1 might play a pivotal role in the process of metamorphosis. Moreover, pierisin-1 could contribute as a defense factor against parasitization and microbial infections in the cabbage butterfly. Pierisin-like proteins in butterflies were shown to be present not only among the subtribe Pierina but also among the subtribes Aporiina and Appiadina, and pierisin-2, -3, and -4 were identified in these butterflies. Furthermore, DNA ADP-ribosylating activities were found in six different edible clams. Understanding of the biological nature of pierisin-1 with DNA mono-ADP-ribosylating activity could open up exciting avenues for research and potential therapeutic applications, making it a subject of great interest in the field of molecular biology and biotechnology. Full article

The Transforming Growth Factor-β (TGF-β) cascade plays a critical role in insect metamorphosis and involves cell-surface receptors known as type I and II, respectively (TβRI and TβRII). In Drosophila melanogaster, the TβRI receptor, Baboon (Babo), consists of three variants (BaboA, BaboB, and BaboC), each with isoform-specific functions. However, the isoforms and functional specifications of Babo in non-Drosophilid insects have not been established. Here, we examined babo transcripts from seven coleopteran species whose genomes have been published and found that mutually exclusive alternative splicing of the third exon produces three babo isoforms, identical to the Drosophila babo gene. The same three transcript variants were accordingly recognized from the transcriptome data of a coleopteran Henosepilachna vigintioctopunctata. RNA interference (RNAi)-mediated knockdown of all three babo transcripts at the fourth-instar larval stage hindered gut modeling and arrested larval development in H. vigintioctopunctata. All the resultant larvae became arrested prepupae; they were gradually dried and darkened and, eventually, died. Depletion of HvbaboA rather than HvbaboB or HvbaboC is similar to the phenotypic alterations caused by simultaneous RNAi of all three babo isoforms. Therefore, our results established diverged roles of the three Babo isoforms and highlighted the regulatory role of BaboA during larval-pupal transition in a non-Drosophilid insect species. Full article

Phenotypic traits can evolve independently at different stages of ontogeny, optimizing adaptation to distinct ecological contexts and increasing morphological diversity in species with complex life cycles. Given the relative independence resulting from the profound changes induced by metamorphosis, niche occupation and resource utilization in tadpoles may prompt evolutionary responses that do not necessarily affect the adults. Consequently, diversity patterns observed in the larval shape may not necessarily correspond to those found in the adult shape for the same species, a premise that can be tested through the Adaptive Decoupling Hypothesis (ADH). Herein, we investigate the ADH for larval and adult shape differentiation in Neoaustrarana frogs. Neoaustrarana frogs, particularly within the Cycloramphidae family, exhibit remarkable diversity in tadpole morphology, making them an ideal model for studying adaptive decoupling. By analyzing 83 representative species across four families (Alsodidae, Batrachylidae, Cycloramphidae, and Hylodidae), we generate a morphological dataset for both larval and adult forms. We found a low correlation between larval and adult shapes, species with a highly distinct larval shape having relatively similar shape when adults. Larval morphological disparity is not a good predictor for adult morphological disparity within the group, with distinct patterns observed among families. Differences between families are notable in other aspects as well, such as the role of allometric components influencing shape and morphospace occupancy. The larval shape has higher phylogenetic structure than the adult. Evolutionary convergence emerges as a mechanism of diversification for both larval and adult shapes in the early evolution of neoaustraranans, with shape disparity of tadpoles reaching stable levels since the Oligocene. The widest occupation in morphospace involves families associated with dynamically changing environments over geological time. Our findings support the ADH driving phenotypic diversity in Neoaustrarana, underscoring the importance of considering ontogenetic stages in evolutionary studies. Full article