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Developmental Cell May 2022Drosophila has long been a successful model organism in multiple biomedical fields. Spatial gene expression patterns are critical for the understanding of complex...
Drosophila has long been a successful model organism in multiple biomedical fields. Spatial gene expression patterns are critical for the understanding of complex pathways and interactions, whereas temporal gene expression changes are vital for studying highly dynamic physiological activities. Systematic studies in Drosophila are still impeded by the lack of spatiotemporal transcriptomic information. Here, utilizing spatial enhanced resolution omics-sequencing (Stereo-seq), we dissected the spatiotemporal transcriptomic changes of developing Drosophila with high resolution and sensitivity. We demonstrated that Stereo-seq data can be used for the 3D reconstruction of the spatial transcriptomes of Drosophila embryos and larvae. With these 3D models, we identified functional subregions in embryonic and larval midguts, uncovered spatial cell state dynamics of larval testis, and revealed known and potential regulons of transcription factors within their topographic background. Our data provide the Drosophila research community with useful resources of organism-wide spatiotemporally resolved transcriptomic information across developmental stages.
Topics: Animals; Drosophila; Gene Expression Regulation, Developmental; Larva; Male; Transcription Factors; Transcriptome
PubMed: 35512700
DOI: 10.1016/j.devcel.2022.04.006 -
Developmental Dynamics : An Official... Jun 2021Amphibians display very diverse life cycles and development can be direct, where it occurs in ovo and a juvenile hatches directly, or biphasic, where an aquatic larva...
Amphibians display very diverse life cycles and development can be direct, where it occurs in ovo and a juvenile hatches directly, or biphasic, where an aquatic larva hatches and later undergoes metamorphosis followed by sexual maturation. In both cases, metamorphosis, corresponds to the post embryonic transition (PETr). A third strategy, only found in Urodeles, is more complex as larvae reach sexual maturity before metamorphosis, which can become accessory. The resulting paedomorphs retain their larval characters and keep their aquatic habitat. Does it mean that paedomorphs do not undergo PETr? Recent work using high throughput technologies coupled to system biology and developmental endocrinology revisited this question and provided novel datasets indicating that a paedomorph's "larval" tissue undergoes a proper developmental transition. Together with historical data, we propose that this transition is a marker of the PETr, which would be distinct from metamorphosis. This implies that (a) complex life cycles would result from the uncoupling of PETr and metamorphosis, and (b) biphasic life cycles would be a special cases where they occur simultaneously.
Topics: Amphibians; Animals; Larva; Life Cycle Stages; Metamorphosis, Biological
PubMed: 33527613
DOI: 10.1002/dvdy.304 -
Current Biology : CB Jan 2021Animals display a diversity of life cycles, including larvae in some lineages but not in others. A new study reveals a shared genetic toolkit in many animals that...
Animals display a diversity of life cycles, including larvae in some lineages but not in others. A new study reveals a shared genetic toolkit in many animals that regulates the transition to the juvenile form, from an embryo or a larva.
Topics: Animals; Biological Evolution; Larva; Life Cycle Stages
PubMed: 33434485
DOI: 10.1016/j.cub.2020.10.089 -
Integrative and Comparative Biology Sep 2021Ascidians are invertebrate chordates, with swimming chordate tadpole larvae that have distinct heads and tails. The head contains the small brain, sensory organs,... (Review)
Review
Ascidians are invertebrate chordates, with swimming chordate tadpole larvae that have distinct heads and tails. The head contains the small brain, sensory organs, including the ocellus (light) and otolith (gravity) and the presumptive endoderm, while the tail has a notochord surrounded by muscle cells and a dorsal nerve cord. One of the chordate features is a post-anal tail. Ascidian tadpoles are nonfeeding, and their tails are critical for larval locomotion. After hatching the larvae swim up toward light and are carried by the tide and ocean currents. When competent to settle, ascidian tadpole larvae swim down, away from light, to settle and metamorphose into a sessile adult. Tunicates are classified as chordates because of their chordate tadpole larvae; in contrast, the sessile adult has a U-shaped gut and very derived body plan, looking nothing like a chordate. There is one group of ascidians, the Molgulidae, where many species are known to have tailless larvae. The Swalla Lab has been studying the evolution of tailless ascidian larvae in this clade for over 30 years and has shown that tailless larvae have evolved independently several times in this clade. Comparison of the genomes of two closely related species, the tailed Molgula oculata and tailless Molgula occulta reveals much synteny, but there have been multiple insertions and deletions that have disrupted larval genes in the tailless species. Genomics and transcriptomics have previously shown that there are pseudogenes expressed in the tailless embryos, suggesting that the partial rescue of tailed features in their hybrid larvae is due to the expression of intact genes from the tailed parent. Yet surprisingly, we find that the notochord gene regulatory network is mostly intact in the tailless M. occulta, although the notochord does not converge and extend and remains as an aggregate of cells we call the "notoball." We expect that eventually many of the larval gene networks will become evolutionarily lost in tailless ascidians and the larval body plan abandoned, with eggs developing directly into an adult. Here we review the current evolutionary and developmental evidence on how the molgulids lost their tails.
Topics: Animals; Biological Evolution; Larva; Notochord; Tail; Urochordata
PubMed: 33881514
DOI: 10.1093/icb/icab022 -
Scientific Reports Jun 2021Chemosensory signals allow vertebrates and invertebrates not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid...
Chemosensory signals allow vertebrates and invertebrates not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid unpleasant or even poisonous substrates. Ethanol is a substance found in the natural environment of Drosophila melanogaster. Accordingly, D. melanogaster has evolved specific sensory systems, physiological adaptations, and associated behaviors at its larval and adult stage to perceive and process ethanol. To systematically analyze how D. melanogaster larvae respond to naturally occurring ethanol, we examined ethanol-induced behavior in great detail by reevaluating existing approaches and comparing them with new experiments. Using behavioral assays, we confirm that larvae are attracted to different concentrations of ethanol in their environment. This behavior is controlled by olfactory and other environmental cues. It is independent of previous exposure to ethanol in their food. Moreover, moderate, naturally occurring ethanol concentration of 4% results in increased larval fitness. On the contrary, higher concentrations of 10% and 20% ethanol, which rarely or never appear in nature, increase larval mortality. Finally, ethanol also serves as a positive teaching signal in learning and memory and updates valence associated with simultaneously processed odor information. Since information on how larvae perceive and process ethanol at the genetic and neuronal level is limited, the establishment of standardized assays described here is an important step towards their discovery.
Topics: Animals; Behavior, Animal; Drosophila melanogaster; Ethanol; Larva; Learning; Neurons; Odorants; Smell
PubMed: 34112872
DOI: 10.1038/s41598-021-91677-3 -
Cellular and Molecular Life Sciences :... Nov 2020Drosophila larvae need to adapt their metabolism to reach a critical body size to pupate. This process needs food resources and has to be tightly adjusted to control... (Review)
Review
Drosophila larvae need to adapt their metabolism to reach a critical body size to pupate. This process needs food resources and has to be tightly adjusted to control metamorphosis timing and adult size. Nutrients such as amino acids either directly present in the food or obtained via protein digestion play key regulatory roles in controlling metabolism and growth. Amino acids act especially on two organs, the fat body and the brain, to control larval growth, body size developmental timing and pupariation. The expression of specific amino acid transporters in fat body cells, and in the brain through specific neurons and glial cells is essential to activate downstream molecular signaling pathways in response to amino acid levels. In this review, we highlight some of these specific networks dependent on amino acid diet to control DILP levels, and by consequence larval metabolism and growth.
Topics: Amino Acid Transport Systems; Amino Acids; Animals; Drosophila; Drosophila Proteins; Hormones; Larva; Signal Transduction
PubMed: 32358623
DOI: 10.1007/s00018-020-03535-6 -
Journal of Insect Science (Online) Jul 2020Mosquito-transmitted diseases pose a threat for a great portion of the world population. Chemical insecticides are the main tool for mosquito control. Heavy dependence... (Review)
Review
Mosquito-transmitted diseases pose a threat for a great portion of the world population. Chemical insecticides are the main tool for mosquito control. Heavy dependence on chemicals created several problems such as resistance development in many mosquito species, environmental effects, and human health issues. Other tools for mosquito control were developed and used in some parts of the world. Ribonucleic acid interference (RNAi) is a reverse genetic mechanism that was recently introduced as a new tool for pest control. Regarding mosquito, RNAi was used to study gene function and to discover genes that can be used as targets for control purposes. Several delivery methods are used to induce RNAi in mosquito larvae. Some methods such as injection and soaking are used routinely in RNAi research but have no application in the field. Other methods such as nanoparticles and microbes have some characteristics that make them good candidates for field application. In this report, we will focus on delivery methods for RNAi in mosquito larvae and will give examples for each method.
Topics: Animals; Culicidae; Larva; Mosquito Control; RNA Interference
PubMed: 32725159
DOI: 10.1093/jisesa/ieaa074 -
Trends in Microbiology Jan 2020Zebrafish (Danio rerio) larvae are widely recognized for studying host-pathogen interactions in vivo because of their optical transparency, genetic manipulability, and... (Review)
Review
Zebrafish (Danio rerio) larvae are widely recognized for studying host-pathogen interactions in vivo because of their optical transparency, genetic manipulability, and translational potential. The development of the zebrafish immune system is well understood, thereby use of larvae enables investigation solely in the context of innate immunity. As a result, infection of zebrafish with natural fish pathogens including Mycobacterium marinum has significantly advanced our understanding of bacterial pathogenesis and vertebrate host defense. However, new work using a variety of human pathogens (bacterial, viral, and fungal) has illuminated the versatility of the zebrafish infection model, revealing unexpected and important concepts underlying infectious disease. We propose that this knowledge can inform studies in higher animal models and help to develop treatments to combat human infection.
Topics: Animals; Communicable Diseases; Disease Models, Animal; Drug Resistance, Bacterial; Host-Pathogen Interactions; Humans; Immunity, Innate; Larva; Macrophages; Mycobacterium marinum; Zebrafish
PubMed: 31604611
DOI: 10.1016/j.tim.2019.08.005 -
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 -
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