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Environmental Science & Technology Dec 2023Metamorphosis is a critical process in the life cycle of most marine benthic invertebrates, determining their transition from plankton to benthos. It affects dispersal...
Metamorphosis is a critical process in the life cycle of most marine benthic invertebrates, determining their transition from plankton to benthos. It affects dispersal and settlement and therefore decisively influences the dynamics of marine invertebrate populations. An extended period of metamorphic competence is an adaptive feature of numerous invertebrate species that increases the likelihood of finding a habitat suitable for settlement and survival. We found that crude oil and residues of burnt oil rapidly induce metamorphosis in two different marine invertebrate larvae, a previously unknown sublethal effect of oil pollution. When exposed to environmentally realistic oil concentrations, up to 84% of tested echinoderm larvae responded by undergoing metamorphosis. Similarly, up to 87% of gastropod larvae metamorphosed in response to burnt oil residues. This study demonstrates that crude oil and its burned residues can act as metamorphic inducers in marine planktonic larvae, short-circuiting adaptive metamorphic delay. Future studies on molecular pathways and oil-bacteria-metamorphosis interactions are needed to fully understand the direct or indirect mechanisms of oil-induced metamorphosis in marine invertebrates. With 90% of chronic oiling occurring in coastal areas, this previously undescribed impact of crude oil on planktonic larvae may have global implications for marine invertebrate populations and biodiversity.
Topics: Animals; Petroleum; Invertebrates; Metamorphosis, Biological; Ecosystem; Life Cycle Stages; Larva
PubMed: 37963269
DOI: 10.1021/acs.est.3c05194 -
Current Opinion in Genetics &... Aug 2007The insect compound eye is one of the most precise and highly ordered patterns in the living world. It develops from an unpatterned simple epithelium by a series of cell... (Review)
Review
The insect compound eye is one of the most precise and highly ordered patterns in the living world. It develops from an unpatterned simple epithelium by a series of cell fate decisions and complex morphogenetic movements. In the first days of metamorphosis, this interplay is particularly noticeable. Recent insights have revealed how interactions between neighboring cells drive the process. Interaction between Delta on cone cells and Notch proteins on the surface of their neighbors induces the first pigment cells to differentiate. The primary pigment cells then express a Nephrin protein, Hibris, that interacts with a different Nephrin, Roughest, on their neighbors. Heterophilic adhesion between Hibris and Roughest results in remodeling contacts between cells to favor their contact with the pigment cells. In conjunction, the primary pigment cells signal to their neighbors through the EGF receptor to survive, rather than undergo apoptosis. This sorting and culling process results in a sculpted pattern with a precise number and position of cells that is repeated hundreds of times in each compound eye.
Topics: Animals; Body Patterning; Cell Lineage; Cell Proliferation; Drosophila; Drosophila Proteins; Eye; Gene Expression Regulation, Developmental; Metamorphosis, Biological; Models, Biological
PubMed: 17618111
DOI: 10.1016/j.gde.2007.05.001 -
PLoS Genetics Oct 2022The corpora allata and the prothoracic glands control moulting and metamorphosis in insects. These endocrine glands are specified in the maxillary and labial segments at...
The corpora allata and the prothoracic glands control moulting and metamorphosis in insects. These endocrine glands are specified in the maxillary and labial segments at positions homologous to those forming the trachea in more posterior segments. Glands and trachea can be homeotically transformed into each other suggesting that all three evolved from a metamerically repeated organ that diverged to form glands in the head and respiratory organs in the trunk. While much is known about tracheal specification, there is limited information about corpora allata and prothorathic gland specification. Here we show that the expression of a key regulator of early gland development, the snail gene, is controlled by the Dfd and Scr Hox genes and by the Hedgehog and Wnt signalling pathways that induce localised transcription of upd, the ligand of the JAK/STAT signalling pathway, which lies at the heart of gland specification. Our results show that the same upstream regulators are required for the early gland and tracheal primordia specification, reinforcing the hypothesis that they originated from a segmentally repeated organ present in an ancient arthropod.
Topics: Animals; Genes, Homeobox; Insecta; Ligands; Metamorphosis, Biological; Molting
PubMed: 36191039
DOI: 10.1371/journal.pgen.1010427 -
Brazilian Journal of Biology = Revista... 2019The present study assessed the percentage of survival and metamorphosis of larval stages of Caligus rogercresseyi (Boxshall and Bravo, 2000) nauplius I, nauplius II to...
Evaluation of survival and metamorphosis of larvae of Caligus rogercresseyi (Boxshall and Bravo, 2000) (Crustacea, Copepoda) in Chile, depending on temperature, salinity and oxygen.
The present study assessed the percentage of survival and metamorphosis of larval stages of Caligus rogercresseyi (Boxshall and Bravo, 2000) nauplius I, nauplius II to and nauplius II to copepodite, conducting bioassays in triplicate with 50 larvae each, nauplius I or nauplius II, at temperature of 12 °C, 15 °C and 18 °C; salinity 20, 23, 25, 2729, 31, 33 and 35 g/L and oxygen saturation with ranges between 30-60%, 90-100% and 190 - 200%. Bioassays were performed in station Quillaipe of Fundación Chile, Puerto Montt, Chile. It is concluded that the temperature is inversely proportional to the time of metamorphosis and survival of the larvae of Caligus rogercresseyi . In salinity is observed that increased this, greater is the percentage of survival and metamorphosis is faster, while the larvae do not survive less than 20g/L. Oxygen saturation ranges indicate that the larvae do not survive at saturations between 30-60%, and it had no differences between 90-100% saturation and 190-200%.
Topics: Animals; Chile; Copepoda; Larva; Metamorphosis, Biological; Oxygen; Salinity; Seawater; Temperature
PubMed: 30066732
DOI: 10.1590/1519-6984.173162 -
BMC Genomics Jun 2018Anuran metamorphosis, which is obligatorily initiated and sustained by thyroid hormone (TH), is a dramatic example of extensive morphological, biochemical and cellular...
BACKGROUND
Anuran metamorphosis, which is obligatorily initiated and sustained by thyroid hormone (TH), is a dramatic example of extensive morphological, biochemical and cellular changes occurring during post-embryonic development. Thus, it provides an ideal model to understand the actions of the hormone and molecular mechanisms underlying these developmental and apoptotic processes. In addition to transcriptional factors, microRNAs (miRNAs) play key roles in diverse biological processes via post-transcriptional repression of mRNAs. However, the possible role of miRNAs in anuran metamorphosis is not well understood. Screening and identification of TH-responding miRNAs are required to reveal the integrated regulatory mechanisms of TH during metamorphosis. Given the specific role of TRs during M. fissipes metamorphosis and the characteristics of M. fissipes as an ideal model, Illumina sequencing technology was employed to get a full scope of miRNA in M. fissipes metamorphosis treated by T3.
RESULTS
Morphological and histological analysis revealed that 24 h T3 treatment M. fissipes tadpoles resembled that at the climax of natural metamorphosis. Thus, small RNA libraries were constructed from control and 24 h T3 treatment groups. A total of 164 conserved miRNAs and 36 predicted novel miRNAs were characterized. Furthermore, 5' first and ninth nucleotides of miRNAs were significantly enriched in U in our study. In all, 21 miRNAs were differentially expressed between the T3 and control groups (p < 0.01). A total of 10,206 unigenes were identified as target genes of these differentially expressed miRNAs. KEGG pathway analysis indicated that the most overrepresented miRNA target genes were enriched in the "PI3k-Akt signaling pathway". In addition, a network associated with the TH signaling pathway provides an opportunity to further understand the complex biological processes that occur in metamorphosis.
CONCLUSIONS
We identified a large number of miRNAs during M. fissipes metamorphosis, and 21 of them were differentially expressed in the two groups that represented two different metamorphic stages. These miRNAs may play important roles during metamorphosis. The study gives us clues for further studies of the mechanisms of anuran metamorphosis and provides a model to study the mechanism of TH-affected biological processes in humans.
Topics: Animals; Anura; Female; Gene Expression Regulation, Developmental; Intestines; Larva; Male; Metamorphosis, Biological; MicroRNAs; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Thyroid Hormones; Triiodothyronine
PubMed: 29954327
DOI: 10.1186/s12864-018-4848-x -
BMC Developmental Biology Jul 2020Before metamorphosis, almost all anuran tadpoles are omnivores. Larval carnivory occurs in some species and, it is associated with distinctive morphotypes. Obligatory...
BACKGROUND
Before metamorphosis, almost all anuran tadpoles are omnivores. Larval carnivory occurs in some species and, it is associated with distinctive morphotypes. Obligatory carnivorous tadpoles exhibit structural changes in the gastrointestinal tract compared to larvae that are predominately omnivores. The most distinctive feature of the anuran family Ceratophyridae (three genera) overall is the enormous gape of adults. This feature increases their ability to capture extremely large and active prey. The larvae of Ceratophyrid genera are remarkably distinct from each other and carnivory has diversified in a manner unseen in other anurans. The larvae of one genus, Lepidobatrachus, has a massive gape like the adult. Herein, we report on larval developmental variation, diet, gross morphology of the gastrointestinal tract, and histology of the cranial segment of the gut before, during and after metamorphosis in larval series for the following ceratophryid species: Chacophrys pierottii, Ceratophrys cranwelli, Lepidobatrachus laevis and Lepidobatrachus llanensis.
RESULTS
We described patterns of larval development with variation in growth with consequence to the final size at the end of metamorphosis. These patterns seem to be influenced by food quantity/quality, and most predominant by animal protein. Prey items found in pre and post-metamorphic Lepidobatrachus spp. are similar. Tadpoles of Ceratophrys and Chacophrys (and other anurans) share a short cranial segment of the gut with an internal glandular, mucous secreting epithelium, a double coiled intestine and the sequence of metamorphic changes (tract is empty, the stomach differentiates and the intestine shortens abruptly). In contrast, Lepidobatrachus tadpoles have a true stomach that acquires thickness and increased glandular complexity through development. As larvae they have a short intestine without double coils, and the absence of intestine shortening during metamorphosis.
CONCLUSIONS
The larval development of the gastrointestinal tract of Lepidobatrachus is unique compared with that of other free-living anuran larvae. An abrupt metamorphic transformation is missing and most of the adult structural features start to differentiate gradually at the beginning of larval stages.
Topics: Animals; Anura; Biological Evolution; Gastrointestinal Microbiome; Larva; Metamorphosis, Biological
PubMed: 32723314
DOI: 10.1186/s12861-020-00221-5 -
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 -
ELife Jul 2021Individual neurons can undergo drastic structural changes, known as neuronal remodeling or structural plasticity. One example of this is in response to hormones, such as...
Individual neurons can undergo drastic structural changes, known as neuronal remodeling or structural plasticity. One example of this is in response to hormones, such as during puberty in mammals or metamorphosis in insects. However, in each of these examples, it remains unclear whether the remodeled neuron resumes prior patterns of connectivity, and if so, whether the persistent circuits drive similar behaviors. Here, we utilize a well-characterized neural circuit in the larva: the moonwalker descending neuron (MDN) circuit. We previously showed that larval MDN induces backward crawling, and synapses onto the Pair1 interneuron to inhibit forward crawling (Carreira-Rosario et al., 2018). MDN is remodeled during metamorphosis and regulates backward walking in the adult fly. We investigated whether Pair1 is remodeled during metamorphosis and functions within the MDN circuit during adulthood. We assayed morphology and molecular markers to demonstrate that Pair1 is remodeled during metamorphosis and persists in the adult fly. MDN-Pair1 connectivity is lost during early pupal stages, when both neurons are severely pruned back, but connectivity is re-established at mid-pupal stages and persist into the adult. In the adult, optogenetic activation of Pair1 resulted in arrest of forward locomotion, similar to what is observed in larvae. Thus, the MDN-Pair1 neurons are an interneuronal circuit - a pair of synaptically connected interneurons - that is re-established during metamorphosis, yet generates similar locomotor behavior at both larval and adult stages.
Topics: Animals; Drosophila; Drosophila melanogaster; Interneurons; Larva; Locomotion; Metamorphosis, Biological; Motor Neurons; Neuronal Plasticity; Optogenetics; Synapses
PubMed: 34259633
DOI: 10.7554/eLife.69767 -
BMC Developmental Biology Nov 2020Molting is an essential biological process occurring characteristic times throughout the life cycle of holometabolous insects. However, it is not clear how insects...
BACKGROUND
Molting is an essential biological process occurring characteristic times throughout the life cycle of holometabolous insects. However, it is not clear how insects determine the direction of molting to remain status quo or to initiate metamorphosis. To explore the functional factors that determine the direction of molts, liquid chromatography-mass spectrometry was used to identify the molecules involved in larval and metamorphic molting, and the differentially expressed proteins (DEPs) were compared in the two processes.
RESULTS
There were 321 and 1140 DEPs identified in larval and metamorphic molting process, respectively. Bioinformatics analyses show that the amino sugar pathway was up-regulated in both processes. The up-regulated protease contributed to the metamorphosis. In addition, several proteins with different expression patterns in larval-larval and larval-pupal transitions, including Endochitinase, GRIM-19 (Genes associated with retinoid-IFN-induced mortality-19), IDE (Insulin-degrading enzyme), Sorcin (Soluble resistance related calcium binding protein), OBP (Odorant-binding protein-2 precursor), TRAP1(Tumor necrosis factor receptor associated protein-1), etc., were further identified by parallel reaction monitoring, which may play diverse functions in larval-larval and larval-pupal transitions.
CONCLUSIONS
These results provide a proteomic insight into molecules involved in larval and metamorphic molts, and will likely improve the current understanding of determination of direction of molts.
Topics: Animals; Gene Expression Regulation, Developmental; Insect Proteins; Larva; Lepidoptera; Metamorphosis, Biological; Molting; Proteomics; Pupa; Reproducibility of Results
PubMed: 33234135
DOI: 10.1186/s12861-020-00227-z -
Philosophical Transactions of the Royal... Oct 2019Developmental, genetic and endocrine data from diverse taxa provide insight into the evolution of insect metamorphosis. We equate the larva-pupa-adult of the...
Developmental, genetic and endocrine data from diverse taxa provide insight into the evolution of insect metamorphosis. We equate the larva-pupa-adult of the Holometabola to the pronymph-nymph-adult of hemimetabolous insects. The hemimetabolous pronymph is a cryptic embryonic stage with unique endocrinology and behavioural modifications that probably served as preadaptations for the larva. It develops in the absence of juvenile hormone (JH) as embryonic primordia undergo patterning and morphogenesis, the processes that were arrested for the evolution of the larva. Embryonic JH then drives tissue differentiation and nymph formation. Experimental treatment of pronymphs with JH terminates patterning and induces differentiation, mimicking the processes that occurred during the evolution of the larva. Unpatterned portions of primordia persist in the larva, becoming imaginal discs that form pupal and adult structures. Key transcription factors are associated with the holometabolous life stages: Krüppel-homolog 1 (Kr-h1) in the larva, broad in the pupa and E93 in the adult. Kr-h1 mediates JH action and is found whenever JH acts, while the other two genes direct the formation of their corresponding stages. In hemimetabolous forms, the pronymph has low Broad expression, followed by Broad expression through the nymphal moults, then a switch to E93 to form the adult. This article is part of the theme issue 'The evolution of complete metamorphosis'.
Topics: Animals; Biological Evolution; Insect Proteins; Insecta; Juvenile Hormones; Larva; Metamorphosis, Biological; Nymph; Pupa
PubMed: 31438820
DOI: 10.1098/rstb.2019.0070