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ELife Mar 2023The way neurons in the brain rewire in larvae as they turn to adult fruit flies sheds light on how complete metamorphosis was 'invented' over the course of evolution.
The way neurons in the brain rewire in larvae as they turn to adult fruit flies sheds light on how complete metamorphosis was 'invented' over the course of evolution.
Topics: Animals; Brain; Arthropods; Fruit; Larva; Metamorphosis, Biological
PubMed: 36867155
DOI: 10.7554/eLife.86696 -
Methods in Cell Biology 2019Echinoderms are favored study organisms not only in cell and developmental biology, but also physiology, larval biology, benthic ecology, population biology and... (Review)
Review
Echinoderms are favored study organisms not only in cell and developmental biology, but also physiology, larval biology, benthic ecology, population biology and paleontology, among other fields. However, many echinoderm embryology labs are not well-equipped to continue to rear the post-embryonic stages that result. This is unfortunate, as such labs are thus unable to address many intriguing biological phenomena, related to their own cell and developmental biology studies, that emerge during larval and juvenile stages. To facilitate broader studies of post-embryonic echinoderms, we provide here our collective experience rearing these organisms, with suggestions to try and pitfalls to avoid. Furthermore, we present information on rearing larvae from small laboratory to large aquaculture scales. Finally, we review taxon-specific approaches to larval rearing through metamorphosis in each of the four most commonly-studied echinoderm classes-asteroids, echinoids, holothuroids and ophiuroids.
Topics: Animals; Developmental Biology; Echinodermata; Larva; Metamorphosis, Biological
PubMed: 30777174
DOI: 10.1016/bs.mcb.2018.11.004 -
Cells May 2022In multicellular organisms, development is based in part on the integration of communication systems. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the... (Review)
Review
In multicellular organisms, development is based in part on the integration of communication systems. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-adrenal/interrenal axes, are central players in orchestrating body morphogenesis. In all vertebrates, the hypothalamic-pituitary-thyroid axis controls thyroid hormone production and release, whereas the hypothalamic-pituitary-adrenal/interrenal axis regulates the production and release of corticosteroids. One of the most salient effects of thyroid hormones and corticosteroids in post-embryonic developmental processes is their critical role in metamorphosis in anuran amphibians. Metamorphosis involves modifications to the morphological and biochemical characteristics of all larval tissues to enable the transition from one life stage to the next life stage that coincides with an ecological niche switch. This transition in amphibians is an example of a widespread phenomenon among vertebrates, where thyroid hormones and corticosteroids coordinate a post-embryonic developmental transition. The review addresses the functions and interactions of thyroid hormone and corticosteroid signaling in amphibian development (metamorphosis) as well as the developmental roles of these two pathways in vertebrate evolution.
Topics: Adrenal Cortex Hormones; Amphibians; Animals; Metamorphosis, Biological; Thyroid Gland; Thyroid Hormones; Vertebrates
PubMed: 35626631
DOI: 10.3390/cells11101595 -
ELife Dec 2023Experiments exploring the role of juvenile hormone during the life cycle of firebrat insects provide clues about the evolution of metamorphosis.
Experiments exploring the role of juvenile hormone during the life cycle of firebrat insects provide clues about the evolution of metamorphosis.
Topics: Animals; Metamorphosis, Biological; Insecta; Life Cycle Stages; Juvenile Hormones
PubMed: 38126357
DOI: 10.7554/eLife.94410 -
Current Opinion in Neurobiology Oct 2023The transition from larval to adult locomotion in the anuran, Xenopus laevis, involves a dramatic switch from axial to appendicular swimming including intermediate... (Review)
Review
The transition from larval to adult locomotion in the anuran, Xenopus laevis, involves a dramatic switch from axial to appendicular swimming including intermediate stages when the tail and hindlimbs co-exist and contribute to propulsion. Hatchling tadpole swimming is generated by an axial central pattern generator (CPG) which matures rapidly during early larval life. During metamorphosis, the developing limbs are controlled by a de novo appendicular CPG driven initially by the axial system before segregating to allow both systems to operate together or independently. Neuromodulation plays important roles throughout, but key modulators switch their effects from early inhibitory influences to facilitating locomotion. Temperature affects the construction and operation of locomotor networks and global changes in environmental temperature place aquatic poikilotherms, like amphibians, at risk. The locomotor control strategy of anurans differs from other amphibian groups such as salamanders, where evolution has acted upon the thyroid hormone pathway to sculpt different developmental outcomes.
Topics: Animals; Spinal Cord; Larva; Locomotion; Swimming; Anura; Metamorphosis, Biological
PubMed: 37549591
DOI: 10.1016/j.conb.2023.102753 -
Annual Review of Entomology Jan 2017MicroRNAs (miRNAs) are involved in the regulation of a number of processes associated with metamorphosis, either in the less modified hemimetabolan mode or in the more... (Review)
Review
MicroRNAs (miRNAs) are involved in the regulation of a number of processes associated with metamorphosis, either in the less modified hemimetabolan mode or in the more modified holometabolan mode. The miR-100/let-7/miR-125 cluster has been studied extensively, especially in relation to wing morphogenesis in both hemimetabolan and holometabolan species. Other miRNAs also participate in wing morphogenesis, as well as in programmed cell and tissue death, neuromaturation, neuromuscular junction formation, and neuron cell fate determination, typically during the pupal stage of holometabolan species. A special case is the control of miR-2 over Kr-h1 transcripts, which determines adult morphogenesis in the hemimetabolan metamorphosis. This is an elegant example of how a single miRNA can control an entire process by acting on a crucial mediator; however, this is a quite exceptional mechanism that was apparently lost during the transition from hemimetaboly to holometaboly.
Topics: Animals; Biological Evolution; Insecta; Metamorphosis, Biological; MicroRNAs
PubMed: 27813669
DOI: 10.1146/annurev-ento-031616-034925 -
Current Biology : CB Jun 2019Many animals undergo a transition during their lifetime from a larval to an adult form, a major developmental change known as metamorphosis. This developmental process,...
Many animals undergo a transition during their lifetime from a larval to an adult form, a major developmental change known as metamorphosis. This developmental process, which involves behavioural, morphological, physiological and biochemical changes, has a broad phylogenetic distribution, occurring in diverse branches of the animal kingdom, from invertebrates (molluscs, arthropods, tunicates) to certain classes of vertebrates, including amphibians (Figure 1). This phenomenon, which has fascinated biologists for centuries, remains an attractive experimental model for studying mechanisms of post-embryonic development as well as molecular mechanisms underlying hormonal regulation.
Topics: Amphibians; Animals; Larva; Locomotion; Metamorphosis, Biological; Nerve Net; Neuronal Plasticity; Respiration
PubMed: 31211970
DOI: 10.1016/j.cub.2019.05.005 -
Philosophical Transactions of the Royal... Oct 2019Many animals depend on microbial symbionts to provide nutrition, defence or other services. Holometabolous insects, as well as other animals that undergo metamorphosis,... (Review)
Review
Many animals depend on microbial symbionts to provide nutrition, defence or other services. Holometabolous insects, as well as other animals that undergo metamorphosis, face unique constraints on symbiont maintenance. Microbes present in larvae encounter a radical transformation of their habitat and may also need to withstand chemical and immunological challenges. Metamorphosis also provides an opportunity, in that symbiotic associations can be decoupled over development. For example, some holometabolous insects maintain the same symbiont as larvae and adults, but house it in different tissues; in other species, larvae and adults may harbour entirely different types or numbers of microbes, in accordance with shifts in host diet or habitat. Such flexibility may provide an advantage over hemimetabolous insects, in which selection on adult-stage microbial associations may be constrained by its negative effects on immature stages, and vice versa. Additionally, metamorphosis itself can be directly influenced by symbionts. Across disparate insect taxa, microbes protect hosts from pathogen infection, supply nutrients essential for rebuilding the adult body and provide cues regulating pupation. However, microbial associations remain completely unstudied for many families and even orders of Holometabola, and future research will undoubtedly reveal more links between metamorphosis and microbiota, two widespread features of animal life. This article is part of the theme issue 'The evolution of complete metamorphosis'.
Topics: Animals; Insecta; Larva; Metamorphosis, Biological; Microbiota; Symbiosis
PubMed: 31438811
DOI: 10.1098/rstb.2019.0068 -
Science Translational Medicine Dec 2016
Topics: Larva; Metamorphosis, Biological
PubMed: 28003541
DOI: 10.1126/scitranslmed.aal3700 -
Current Opinion in Insect Science Feb 2021Metamorphosis (Greek for a state of transcending-form or change-in-shape) refers to a dramatic transformation of an animal's body structure that occurs after development... (Review)
Review
Metamorphosis (Greek for a state of transcending-form or change-in-shape) refers to a dramatic transformation of an animal's body structure that occurs after development of the embryo or larva in many species. The development of a fly (or butterfly) from a crawling larva (or caterpillar) that forms a pupa (or chrysalis) before eclosing as a flying adult is a classic example of metamorphosis that captures the imagination and has been immortalized in children's books. Powerful genetic experiments in the fruit fly Drosophila melanogaster have revealed how genes can instruct the behaviour of individual cells to control patterns of tissue growth, mechanical force, cell-cell adhesion and cell-matrix adhesion drive morphogenetic change in epithelial tissues. Together, the distribution of mass, force and resistance determines cell shape changes, cell-cell rearrangements, and/or the orientation of cell divisions to generate the final form of the tissue. In organising tissue shape, genes harness the power of self-organisation to determine the collective behaviour of molecules and cells, which can often be reproduced in computer simulations of cell polarity and/or tissue mechanics. This review highlights fundamental discoveries in epithelial morphogenesis made by pioneers who were fascinated by metamorphosis, including D'Arcy Thompson, Conrad Waddington, Dianne Fristrom and Antonio Garcia-Bellido.
Topics: Animals; Epithelial Cells; Epithelium; Insecta; Metamorphosis, Biological; Morphogenesis
PubMed: 32898719
DOI: 10.1016/j.cois.2020.08.008