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Environmental Science and Pollution... Jul 2022Nitrite, as a part of nitrogen cycle, is one of the most common toxic compounds in aquatic ecosystems. Since skeletal development is an essential process during...
Nitrite, as a part of nitrogen cycle, is one of the most common toxic compounds in aquatic ecosystems. Since skeletal development is an essential process during amphibian metamorphosis, exposure of larval amphibians to nitrite might disrupt skeletal development. To evaluate whether nitrite affects skeletal development of amphibian larvae, Bufo gargarizans larvae at Gs26 were exposed to 10, 100, 500 and 1000 μg/L nitrite-nitrogen (NO-N) in the present study. The metamorphosis rate, body weight, body length, forelimb length and hindlimb length of B. gargarizans exposed to NO-N were decreased. The microscopic structures of thyroid gland were altered under NO-N exposure at Gs42. The skeletal lengths of the humerus, femur and fibulare of tadpole at Gs42 were significantly reduced under 100, 500 and 1000 μg/L NO-N treatment groups, and the lengths of humerus, tibia-fibula and tibiale of tadpole at Gs46 were significantly reduced under 1000 μg/L NO-N treatment groups. In addition, the expression levels of thyroid hormone (TH) and endochondral ossification-related genes of tadpoles at Gs42 and Gs46 were tested by qRT-PCR. Overall, NO-N exposure could affect the expressions of these genes and then may influence the activity and function of thyroid gland, further disturbing the amphibian metamorphosis and skeletal development of amphibian larvae.
Topics: Animals; Bufonidae; Ecosystem; Larva; Metamorphosis, Biological; Nitrites; Nitrogen Dioxide
PubMed: 35253106
DOI: 10.1007/s11356-022-19468-5 -
Developmental Biology Sep 2023The present hypothesis tries to explain animal regeneration in relation to the life cycles and environment of different animals. Regeneration is a basic phenomenon...
The present hypothesis tries to explain animal regeneration in relation to the life cycles and environment of different animals. Regeneration is a basic phenomenon present since the origin of life in the sea, as testimonial in lower or more complex extant marine animals. Aquatic animals that evolved an indirect development, forming larvae and transiting into the adult stage through metamorphosis, use gene networks present in their genome for these transformations. In case of injury or organ loss as adults, they can re-utilize most or part of the gene networks previously activated during larval growth and metamorphosis. In contrast, terrestrial animals that evolved life cycles with the elimination of larvae and metamorphosis for the adaptation to land conditions lost some of the genes implicated in these post-developmental processes and consequently also the ability to regenerate. Few arthropods and lizards are capable to form hydrated regenerative blastemas with a similar consistence of embryonic tissues. The present hypothesis submits that regeneration cannot be activated in the dry land environment and consequently was largely or completely abolished in terrestrial animals. After injury or organ loss, nematodes, most arthropods and terrestrial vertebrates can only form scars or a limited healing or regengrow in juveniles. This is a process where somatic growth is superimposed to wound healing so that the apparent regeneration derives from the combination from both processes. When full growth is terminated these terrestrial animals can only heal by scarring.
Topics: Animals; Wound Healing; Biological Evolution; Cicatrix; Vertebrates; Larva; Metamorphosis, Biological
PubMed: 37353104
DOI: 10.1016/j.ydbio.2023.06.013 -
Scientific Reports Sep 2021Larval metamorphosis in bivalves is a key event for the larva-to-juvenile transformation. Previously we have identified a thyroid hormone receptor (TR) gene that is...
Larval metamorphosis in bivalves is a key event for the larva-to-juvenile transformation. Previously we have identified a thyroid hormone receptor (TR) gene that is crucial for larvae to acquire "competence" for the metamorphic transition in the mussel Mytilus courscus (Mc). The mechanisms of thyroid signaling in bivalves are still largely unknown. In the present study, we molecularly characterized the full-length of two iodothyronine deiodinase genes (McDx and McDy). Phylogenetic analysis revealed that deiodinases of molluscs (McDy, CgDx and CgDy) and vertebrates (D2 and D3) shared a node representing an immediate common ancestor, which resembled vertebrates D1 and might suggest that McDy acquired specialized function from vertebrates D1. Anti-thyroid compounds, methimazole (MMI) and propylthiouracil (PTU), were used to investigate their effects on larval metamorphosis and juvenile development in M. coruscus. Both MMI and PTU significantly reduced larval metamorphosis in response to the metamorphosis inducer epinephrine. MMI led to shell growth retardation in a concentration-dependent manner in juveniles of M. coruscus after 4 weeks of exposure, whereas PTU had no effect on juvenile growth. It is hypothesized that exposure to MMI and PTU reduced the ability of pediveliger larvae for the metamorphic transition to respond to the inducer. The effect of MMI and PTU on larval metamorphosis and development is most likely through a hormonal signal in the mussel M. coruscus, with the implications for exploring the origins and evolution of metamorphosis.
Topics: Animals; Antithyroid Agents; Iodide Peroxidase; Larva; Metamorphosis, Biological; Methimazole; Mytilus; Propylthiouracil; Thyroid Hormones
PubMed: 34588587
DOI: 10.1038/s41598-021-98930-9 -
Proceedings of the National Academy of... Dec 2023The decision to stop growing and mature into an adult is a critical point in development that determines adult body size, impacting multiple aspects of an adult's...
The decision to stop growing and mature into an adult is a critical point in development that determines adult body size, impacting multiple aspects of an adult's biology. In many animals, growth cessation is a consequence of hormone release that appears to be tied to the attainment of a particular body size or condition. Nevertheless, the size-sensing mechanism animals use to initiate hormone synthesis is poorly understood. Here, we develop a simple mathematical model of growth cessation in , which is ostensibly triggered by the attainment of a critical weight (CW) early in the last instar. Attainment of CW is correlated with the synthesis of the steroid hormone ecdysone, which causes a larva to stop growing, pupate, and metamorphose into the adult form. Our model suggests that, contrary to expectation, the size-sensing mechanism that initiates metamorphosis occurs before the larva reaches CW; that is, the critical-weight phenomenon is a downstream consequence of an earlier size-dependent developmental decision, not a decision point itself. Further, this size-sensing mechanism does not require a direct assessment of body size but emerges from the interactions between body size, ecdysone, and nutritional signaling. Because many aspects of our model are evolutionarily conserved among all animals, the model may provide a general framework for understanding how animals commit to maturing from their juvenile to adult form.
Topics: Animals; Drosophila; Drosophila melanogaster; Ecdysone; Body Size; Drosophila Proteins; Larva; Metamorphosis, Biological
PubMed: 38015844
DOI: 10.1073/pnas.2313224120 -
Theoretical Biology Forum Jul 2023Although most discussions on the origin and evolution of insect wings and metamorphosis have assumed that the ancestors of winged insects were terrestrial, it now seems...
Although most discussions on the origin and evolution of insect wings and metamorphosis have assumed that the ancestors of winged insects were terrestrial, it now seems possible that they were actually aquatic. Changing the basic assumptions affects our interpretations of the origin of metamorphosis and our understanding of insect diversity. It is argued that the ancestors of winged insects were similar to primitive mayflies, developing from aquatic larvae into terrestrial adults, and that metamorphosis originated as an inevitable consequence of an amphibiotic life cycle. It is suggested that the first pupae resembled those of Megaloptera.
Topics: Animals; Pupa; Ephemeroptera; Insecta; Metamorphosis, Biological; Pterygota
PubMed: 37638482
DOI: 10.19272/202311402006 -
Proceedings of the National Academy of... May 2022
Topics: Animals; Gene Expression Regulation; Gene Expression Regulation, Developmental; Larva; Metamorphosis, Biological; Transcription Factors
PubMed: 35594389
DOI: 10.1073/pnas.2204972119 -
Scientific Reports Oct 2020Ciona robusta (Ciona intestinalis type A), a model organism for biological studies, belongs to ascidians, the main class of tunicates, which are the closest relatives of...
Ciona robusta (Ciona intestinalis type A), a model organism for biological studies, belongs to ascidians, the main class of tunicates, which are the closest relatives of vertebrates. In Ciona, a project on the ontology of both development and anatomy is ongoing for several years. Its goal is to standardize a resource relating each anatomical structure to developmental stages. Today, the ontology is codified until the hatching larva stage. Here, we present its extension throughout the swimming larva stages, the metamorphosis, until the juvenile stages. For standardizing the developmental ontology, we acquired different time-lapse movies, confocal microscope images and histological serial section images for each developmental event from the hatching larva stage (17.5 h post fertilization) to the juvenile stage (7 days post fertilization). Combining these data, we defined 12 new distinct developmental stages (from Stage 26 to Stage 37), in addition to the previously defined 26 stages, referred to embryonic development. The new stages were grouped into four Periods named: Adhesion, Tail Absorption, Body Axis Rotation, and Juvenile. To build the anatomical ontology, 203 anatomical entities were identified, defined according to the literature, and annotated, taking advantage from the high resolution and the complementary information obtained from confocal microscopy and histology. The ontology describes the anatomical entities in hierarchical levels, from the cell level (cell lineage) to the tissue/organ level. Comparing the number of entities during development, we found two rounds on entity increase: in addition to the one occurring after fertilization, there is a second one during the Body Axis Rotation Period, when juvenile structures appear. Vice versa, one-third of anatomical entities associated with the embryo/larval life were significantly reduced at the beginning of metamorphosis. Data was finally integrated within the web-based resource "TunicAnatO", which includes a number of anatomical images and a dictionary with synonyms. This ontology will allow the standardization of data underpinning an accurate annotation of gene expression and the comprehension of mechanisms of differentiation. It will help in understanding the emergence of elaborated structures during both embryogenesis and metamorphosis, shedding light on tissue degeneration and differentiation occurring at metamorphosis.
Topics: Animals; Cell Differentiation; Embryonic Development; Larva; Metamorphosis, Biological; Microscopy, Confocal; Urochordata
PubMed: 33087765
DOI: 10.1038/s41598-020-73544-9 -
Frontiers in Endocrinology 2020Physiological functions of juvenile hormone (JH) and molting hormone have been demonstrated in insects. JH, molting hormone and their mimics (insect growth regulators,...
Physiological functions of juvenile hormone (JH) and molting hormone have been demonstrated in insects. JH, molting hormone and their mimics (insect growth regulators, IGRs) show endocrine-disrupting effects not only on target pest insects but also on other arthropod species such as crustaceans. However, little is known about the endocrine-disrupting effects of IGRs on benthic crustaceans. In this study, laboratory experiments were conducted to investigate effects of representative innate JH in crustaceans (methyl farnesoate, MF) and molting hormone (20-hydroxyecdysone, 20E, active form of ecdysteroid) on larval stages of the kuruma prawn , which is a decapod crustacean living in warm seawater. Larval development of kuruma prawn progresses in the order of nauplius, zoea, mysis, and then post-larvae with molting and metamorphosis, but it is unknown whether both MF and 20E have crucial roles in metamorphosis and molting of this species. Treatments of either MF or 20E on shrimp larvae were attempted at each developmental stage and those effects were validated. In terms of EC values between mortality and metamorphosis, there were apparent differences in the transition from nauplius to zoea (MF: 7.67 and 0.12 μM; 20E: 3.84 and 0.06 μM in survival and metamorphic rates, respectively). In contrast, EC values in MF and 20E treatments showed high consistency in the transitions between zoea to mysis (EC values for survival; MF: 1.25 and 20E: 0.22 μM), and mysis to post-larvae (EC values for survival; MF: 0.65 and 20E: 0.46 μM). These data suggest that nauplius has strong resistance against exposure to MF and 20E. Moreover, both chemicals induced high mortality triggered by the disruption of molting associated with metamorphosis. To our knowledge, this is the first experimental evidence that investigates physiological functions of MF and 20E in the larval stages of kuruma prawn, shedding light on not only ecotoxicological impacts of IGRs released into nature, but also endocrine mechanisms underlying larval development with metamorphosis in benthic decapod crustaceans.
Topics: Animals; Ecdysterone; Fatty Acids, Unsaturated; Juvenile Hormones; Larva; Metamorphosis, Biological; Penaeidae
PubMed: 32849271
DOI: 10.3389/fendo.2020.00475 -
Aquatic Toxicology (Amsterdam,... Nov 2023The bufonid species Melanophryniscus admirabilis is restricted to a single location in the southern Atlantic Forest, Brazil. Although the site of occurrence of M....
The bufonid species Melanophryniscus admirabilis is restricted to a single location in the southern Atlantic Forest, Brazil. Although the site of occurrence of M. admirabilis is covered with native forest and it is not directly exposed to pesticides application, the area is surrounded by agricultural activity. Our objectives were to evaluate possible alterations in morphological parameters (body mass, snout-vent length, and body index), metamorphosis (time to reach Gosner stages 42, 46 and to complete metamorphosis), and survival of M. admirabilis exposed to isolated Roundup® Original DI (R1: 234 and R2: 2340 µg.L of glyphosate) and Boral® 500 SC, (B1: 130 and B2: 980 µg.L of sulfentrazone) or mixed (R1+B1, R2+B1, R1+B2, R2+B2). Spawns of M. admirabilis were collected in natural lakes in the municipality of Arvorezinha and taken to laboratory cultivation. After the tadpoles acquired free swimming, the animals were acclimated for five days and fed ad libitum. The aquariums were contaminated with herbicides on the sixth day of cultivation, and the animals stayed in these aquariums for four days. Afterwards, the tadpoles were transferred to aquariums with clean water and monitored until metamorphosis (Gosner stage 46), when they were weighed, measured (snout-cloacal length) and cryoeuthanized. We observed no alterations in morphological parameters; however, survival was reduced in exposed groups (mortality index: 71 % in R2 and 29-64 % in mixed groups), suggesting energy allocation for metamorphosis at the expense of survival. Boral did not alter metamorphosis time. Roundup isolated and mixed with Boral altered the timing of Gosner stages 42 and 46 and reduced metamorphosis time, suggesting endocrine disruption. Thus, monitoring the presence and limiting the use of these pesticides in the area where M. admirabilis occurs can be crucial for conservation strategies.
Topics: Animals; Herbicides; Larva; Water Pollutants, Chemical; Bufonidae; Pesticides; Metamorphosis, Biological
PubMed: 37820410
DOI: 10.1016/j.aquatox.2023.106715 -
The Journal of Experimental Biology May 2023Environmental challenges early in development can result in complex phenotypic trade-offs and long-term effects on individual physiology, performance and behavior, with...
Environmental challenges early in development can result in complex phenotypic trade-offs and long-term effects on individual physiology, performance and behavior, with implications for disease and predation risk. We examined the effects of simulated pond drying and elevated water temperatures on development, growth, thermal physiology and behavior in a North American amphibian, Rana sphenocephala. Tadpoles were raised in outdoor mesocosms under warming and drying regimes based on projected climatic conditions in 2070. We predicted that amphibians experiencing the rapid pond drying and elevated pond temperatures associated with climate change would accelerate development, be smaller at metamorphosis and demonstrate long-term differences in physiology and exploratory behavior post-metamorphosis. Although both drying and warming accelerated development and reduced survival to metamorphosis, only drying resulted in smaller animals at metamorphosis. Around 1 month post-metamorphosis, animals from the control treatment jumped relatively farther at high temperatures in jumping trials. In addition, across all treatments, frogs with shorter larval periods had lower critical thermal minima and maxima. We also found that developing under warming and drying resulted in a less exploratory behavioral phenotype, and that drying resulted in higher selected temperatures in a thermal gradient. Furthermore, behavior predicted thermal preference, with less exploratory animals selecting higher temperatures. Our results underscore the multi-faceted effects of early developmental environments on behavioral and physiological phenotypes later in life. Thermal preference can influence disease risk through behavioral thermoregulation, and exploratory behavior may increase risk of predation or pathogen encounter. Thus, climatic stressors during development may mediate amphibian exposure and susceptibility to predators and pathogens into later life stages.
Topics: Animals; Anura; Metamorphosis, Biological; Larva; Ranidae; Ponds
PubMed: 37039737
DOI: 10.1242/jeb.244883