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Biological Reviews of the Cambridge... May 2018Scyphozoan jellyfish, or scyphomedusae, are conspicuous members of many ocean ecosystems, and have large impacts on human health and industry. Most scyphomedusae are the... (Review)
Review
Scyphozoan jellyfish, or scyphomedusae, are conspicuous members of many ocean ecosystems, and have large impacts on human health and industry. Most scyphomedusae are the final stage in a complex life cycle that also includes two intermediate stages: the larval planula and benthic polyp. In species with all three life-cycle stages, the metamorphosis of a polyp into a juvenile scyphomedusa (ephyra) is termed strobilation, and polyps can produce one ephyra (termed monodisc strobilation) or many ephyrae (termed polydisc strobilation). In contrast to species with planula, polyp and medusa stages, a handful of scyphozoan species possess modified life cycles with reduced or absent stages. The evolutionary patterns associated with strobilation and life-cycle type have not been thoroughly investigated, and many studies of ephyra development and strobilation induction are not yet synthesized. Herein, I place the development of scyphomedusae in an evolutionary context. I first review the current evolutionary hypotheses for Scyphozoa. Next, I review what is known about scyphomedusa development across a broad diversity of species, including the first signs of strobilation, the formation of strobila segments, and the morphogenesis of ephyrae. I then review cases where the canonical scyphozoan life cycle has been modified, and take advantage of phylogenetic hypotheses to place these observations in an evolutionary context. I show that the evolution of monodisc strobilation occurred at least twice, and that the loss of intermediate life-cycle stages occurred several times independently; by contrast, the reduction of the medusa stage appears to have occurred within a single clade. I then briefly review the major natural cues of strobilation induction. Finally, I summarize what is currently known about the molecular mechanisms of strobilation induction and ephyra development. I conclude with suggestions for future directions in the field.
Topics: Animals; Life Cycle Stages; Metamorphosis, Biological; Phylogeny; Scyphozoa
PubMed: 29446223
DOI: 10.1111/brv.12393 -
Advances in Kidney Disease and Health Nov 2023
Topics: Humans; Kidney Diseases; Metamorphosis, Biological; Diet
PubMed: 37988040
DOI: 10.1053/j.akdh.2023.10.005 -
Frontiers in Cellular and Infection... 2023Tapeworm larvae cause important diseases in humans and domestic animals. During infection, the first larval stage undergoes a metamorphosis where tissues are formed...
BACKGROUND
Tapeworm larvae cause important diseases in humans and domestic animals. During infection, the first larval stage undergoes a metamorphosis where tissues are formed from a population of stem cells called germinative cells. This process is difficult to study for human pathogens, as these larvae are infectious and difficult to obtain in the laboratory.
METHODS
In this work, we analyzed cell proliferation and differentiation during larval metamorphosis in the model tapeworm , by labelling of proliferating cells with the thymidine analogue 5-ethynyl-2'-deoxyuridine (EdU), tracing their differentiation with a suite of specific molecular markers for different cell types.
RESULTS
Proliferating cells are very abundant and fast-cycling during early metamorphosis: the total number of cells duplicates every ten hours, and the length of G2 is only 75 minutes. New tegumental, muscle and nerve cells differentiate from this pool of proliferating germinative cells, and these processes are very fast, as differentiation markers for neurons and muscle cells appear within 24 hours after exiting the cell cycle, and fusion of new cells to the tegumental syncytium can be detected after only 4 hours. Tegumental and muscle cells appear from early stages of metamorphosis (24 to 48 hours post-infection); in contrast, most markers for differentiating neurons appear later, and the detection of synapsin and neuropeptides correlates with scolex retraction. Finally, we identified populations of proliferating cells that express conserved genes associated with neuronal progenitors and precursors, suggesting the existence of tissue-specific lineages among germinative cells.
DISCUSSION
These results provide for the first time a comprehensive view of the development of new tissues during tapeworm larval metamorphosis, providing a framework for similar studies in human and veterinary pathogens.
Topics: Animals; Humans; Hymenolepis; Metamorphosis, Biological; Cell Differentiation; Muscles; Cell Proliferation; Larva
PubMed: 37908761
DOI: 10.3389/fcimb.2023.1286190 -
Scientific Reports Oct 2023Exploring the timing of life-history transitions has been a pivotal focus in the field of evolutionary ecology. Studies on amphibian metamorphosis are well suited to...
Exploring the timing of life-history transitions has been a pivotal focus in the field of evolutionary ecology. Studies on amphibian metamorphosis are well suited to investigate this aspect. We propose a species-specific model to predict the optimal metamorphosis point for frog individuals with different larval growth trajectories. Because overall fitness will be determined throughout both aquatic and terrestrial stages, we included growth and survival rates of aquatic and terrestrial stages in the fitness equation. Then we conducted a rearing experiment on a brown frog, Rana ornativentris, as an example to obtain the size at metamorphosis, larval period, and larval growth trajectory. Based on these results, we determined the model's parameters to fit the actual metamorphosis patterns. Because the parameters are supposed to be evolutionarily maintained, our data-driven approach enabled obtaining fundamental ecological information (evolutionally-based life-history parameters) of the target species. Comparing the parameters among species will allow us to understand the mechanisms in determining life-history transition more deeply.
Topics: Humans; Animals; Metamorphosis, Biological; Anura; Larva; Ranidae; Morphogenesis
PubMed: 37783741
DOI: 10.1038/s41598-023-43639-0 -
Journal of Thermal Biology May 2018Anurans exhibit plasticity in the timing of metamorphosis and tadpoles show phenotypic plasticity in age and size at metamorphosis as a response to temperature... (Review)
Review
Anurans exhibit plasticity in the timing of metamorphosis and tadpoles show phenotypic plasticity in age and size at metamorphosis as a response to temperature variation. This developmental plasticity to changing thermal conditions is expected to be a primary factor that dictates the vulnerability of amphibians to increasing ambient temperatures such as are predicted in climate change scenarios. We analyzed the patterns of thermal effects on size and age at metamorphosis to investigate whether the intraspecific "temperature-size rule" is applicable over a broad range of anuran species by carrying out a combined analysis based on the data from 25 studies performed on 18 anuran species. Furthermore, we tested whether the thermal background of respective populations impacts the capacity for a plastic response in metamorphic traits. We could confirm this pattern for across-population comparisons. All included populations developed faster and 75% were smaller at the onset of metamorphosis when developmental temperatures were warmer, but the sensitivity of growth and developmental rate to a given temperature change was different. We found that the thermal background of a population influences the sensitivity of metamorphic traits and thus, the capacity for a plastic response in growth and developmental rate. Warm adapted populations were less sensitive to temperature variation indicating a reduced capacity for developmental plasticity and therefore, those species may be more vulnerable to the impacts of climate change. Future studies should include a broader range of rearing temperatures and temperature fluctuations to determine full knowledge of the capacity for developmental plasticity within a species-specific thermal window.
Topics: Animals; Anura; Larva; Metamorphosis, Biological; Temperature; Thermotolerance
PubMed: 29801617
DOI: 10.1016/j.jtherbio.2018.03.005 -
Environmental Pollution (Barking, Essex... Oct 2022Both amphibian metamorphosis assay (AMA) and larval amphibian growth and development assay (LAGDA) can detect thyroid-mediated modality and adversity on the basis of... (Review)
Review
Both amphibian metamorphosis assay (AMA) and larval amphibian growth and development assay (LAGDA) can detect thyroid-mediated modality and adversity on the basis of morphological changes during the thyroid hormone-dependent metamorphosis. They are used for identification of thyroid hormone system disrupting chemicals (TDCs) for non-target organisms or the environment. The EU Guidance recommends that the AMA and the LAGDA should be used to address sufficient investigation of the thyroid-mediated modality and adversity, respectively. In the EU discussions over identification of TDCs, the necessity of using LAGDA as a follow-up of positive results of the AMA has been questioned because of the overlap between the endpoints and the exposure of both tests. This study analyzed similarities, differences, and sensitivity of these two assays in detection of TDCs. For agonists and most of antagonists of the hypothalamic-pituitary-thyroid (HPT) axis, both AMA and LAGDA can detect the thyroid-mediated modality and adversity. The LAGDA, as a follow-up of the positive results of the AMA, may not be needed because the results of AMA are considered enough for identification of TDCs. For chemicals like inhibitors of iodotyrosine deiodinase, the LAGDA is considered necessary for identification of TDCs because the thyroid-mediated adversity cannot be detected until Nieuwkoop and Faber (NF) stage 62. Incorporation of mechanistic endpoints into existing test guidelines and the use of Xenopus Eleutheroembryo Thyroid Assay (XETA), extended amphibian metamorphosis assay (EAMA) and adverse outcome pathways (AOPs) for testing and identification of TDCs are further discussed.
Topics: Animals; Endocrine Disruptors; Larva; Metamorphosis, Biological; Thyroid Gland; Thyroid Hormones; Xenopus laevis
PubMed: 35998776
DOI: 10.1016/j.envpol.2022.120006 -
Genes Dec 2022Metamorphosis is a critical process in the transition from planktonic life to benthic life for marine invertebrates, which is accompanied by a large amount of energy...
Metamorphosis is a critical process in the transition from planktonic life to benthic life for marine invertebrates, which is accompanied by a large amount of energy consumption. Previous studies have proved that AMP-activated protein kinase (AMPK), as a vital energy regulator, plays a prominent role in mediating the growth and development of terrestrial animals. However, its function in the growth and development of marine invertebrates, especially in metamorphosis, remains elusive. This study explored the function of AMPK in the larval metamorphosis of . The full-length cDNA of genes in was cloned and characterized, which is composed of three subunits, , , and . Pharmacological tests demonstrated that through the application of an AMPK activator, AMP substantially enhanced the larval metamorphosis rate ( < 0.05). By contrast, the larval metamorphosis rate decreased significantly after being treated with the AMPK inhibitor Compound C ( < 0.05). gene knock-down resulted in a reduction in gene expression ( < 0.05), and the larval metamorphosis of was significantly restrained ( < 0.05). These results indicated that AMPK signaling is vital in the larval metamorphosis of , which advances further understanding in exploring the molecular mechanisms in the metamorphosis of marine invertebrate larvae.
Topics: Animals; Mytilus; AMP-Activated Protein Kinases; Metamorphosis, Biological; Larva
PubMed: 36553651
DOI: 10.3390/genes13122384 -
Science (New York, N.Y.) Nov 2018
Topics: Adaptation, Physiological; Animals; Anura; Biological Evolution; Caenorhabditis elegans; Cannibalism; Carnivory; Gene-Environment Interaction; Larva; Lizards; Metamorphosis, Biological
PubMed: 30498109
DOI: 10.1126/science.362.6418.988 -
Frontiers in Bioscience (Landmark... Jan 2020In some adult holometabolous insects, specific epithelial tissues form imaginal discs, small sac-like clusters of cells that form in the larval body. During... (Review)
Review
In some adult holometabolous insects, specific epithelial tissues form imaginal discs, small sac-like clusters of cells that form in the larval body. During metamorphosis, in response to hormones, the discs undergo dramatic changes including cell proliferation and differentiation. In Bombyx mori insects, the cuticular protein (CP) genes, which are expressed at prepupal stage in the wing discs, are divided into six groups according to their developmental expression profile and responsiveness to steroid hormones. In this article, we discuss the expression of CP genes in the wing disc, and examine the molecular mechanisms by which metamorphosis and cell transformations are regulated by hormones in insects.
Topics: Animals; Bombyx; Ecdysone; Gene Expression Regulation, Developmental; Imaginal Discs; Insect Proteins; Larva; Metamorphosis, Biological; Pupa; Wings, Animal
PubMed: 31585879
DOI: 10.2741/4796 -
Advances in Protein Chemistry and... 2019Cell-to-cell signaling is responsible for regulation of many developmental processes such as proliferation, cell migration, survival, cell fate specification and axis... (Review)
Review
Cell-to-cell signaling is responsible for regulation of many developmental processes such as proliferation, cell migration, survival, cell fate specification and axis patterning. In this article we discussed the role of signaling in the metamorphosis of sponges with a focus on epithelial-mesenchymal transition (EMT) accompanying this event. Sponges (Porifera) are an ancient lineage of morphologically simple animals occupying a basal position on the tree of life. The study of these animals is necessary for understanding the origin of multicellularity and the evolution of developmental processes. Development of sponges is quite diverse. It finishes with the metamorphosis of a free-swimming larva into a young settled sponge. The outer surface of sponge larvae consists of a ciliated epithelial sheath, which ensures locomotion, while their internal structure varies from genus to genus. The fate of larval ciliated cells is the most intriguing aspect of metamorphosis. In this review we discuss the fate of larval ciliated cells, the processes going on in cells during metamorphosis at the molecular level and the regulation of this process. The review is based on information about several sponge species with a focus on Halisarca dujardini, Sycon ciliatum and Amphimedon queenslandica. In our model sponge, H. dujardini, ciliated cells leave the larval epithelium during metamorphosis and migrate to the internal cell mass as amoeboid cells to be differentiated into choanocytes of the juvenile sponge. Ciliated cells undergo EMT and internalize within minutes. As EMT involves the disappearance of adherens junctions and as cadherin, the main adherens junction protein, was identified in the transcriptome of several sponges, we suppose that EMT is regulated through cadherin-containing adherens junctions between ciliated cells. We failed to identify the master genes of EMT in the H. dujardini transcriptome, possibly because transcription was absent in the sequenced stages. They may be revealed by a search in the genome. The master genes themselves are controlled by various signaling pathways. Sponges have all the six signaling pathways conserved in Metazoa: Wnt, TGF-beta, Hedgehog, Notch, FGF and NO-dependent pathways. Summarizing the new data about intercellular communication in sponges, we can put forward two main questions regarding metamorphosis: (1) Which of the signaling pathways and in what hierarchical order are involved in metamorphosis? (2) How is the organization of a young sponge related to that of the larva or, in other words, is there a heredity of axes between the larva and the adult sponge?
Topics: Animals; Epithelial-Mesenchymal Transition; Larva; Metamorphosis, Biological; Porifera; Signal Transduction
PubMed: 31036299
DOI: 10.1016/bs.apcsb.2019.02.002