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Results and Problems in Cell... 2019Regeneration has fascinated both scientists and non-scientists for centuries. Many organisms can regenerate, and arthropod limbs are no exception although their ability... (Review)
Review
Regeneration has fascinated both scientists and non-scientists for centuries. Many organisms can regenerate, and arthropod limbs are no exception although their ability to regenerate is a product shaped by natural and sexual selection. Recent studies have begun to uncover cellular and molecular processes underlying limb regeneration in several arthropod species. Here we argue that an evo-devo approach to the study of arthropod limb regeneration is needed to understand aspects of limb regeneration that are conserved and divergent. In particular, we argue that limbs of different species are comprised of cells at distinct stages of differentiation at the time of limb loss and therefore provide insights into regeneration involving both stem cell-like cells/precursor cells and differentiated cells. In addition, we review recent studies that demonstrate how limb regeneration impacts the development of the whole organism and argue that studies on the link between local tissue damage and the rest of the body should provide insights into the integrative nature of development. Molecular studies on limb regeneration are only beginning to take off, but comparative studies on the mechanisms of limb regeneration across various taxa should not only yield interesting insights into development but also answer how this remarkable ability evolved across arthropods and beyond.
Topics: Animals; Arthropods; Biological Evolution; Cell Differentiation; Extremities; Regeneration
PubMed: 31598866
DOI: 10.1007/978-3-030-23459-1_17 -
Genome Biology Jan 2020Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a...
BACKGROUND
Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods.
RESULTS
Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception.
CONCLUSIONS
These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity.
Topics: Animals; Arthropods; DNA Methylation; Evolution, Molecular; Genetic Speciation; Genetic Variation; Phylogeny
PubMed: 31969194
DOI: 10.1186/s13059-019-1925-7 -
Philosophical Transactions of the Royal... May 2016Antimicrobial peptides (AMPs) are important elements of the innate immune defence in multicellular organisms that target and kill microbes. Here, we reflect on the... (Review)
Review
Antimicrobial peptides (AMPs) are important elements of the innate immune defence in multicellular organisms that target and kill microbes. Here, we reflect on the various points that are raised by the authors of the 11 contributions to a special issue of Philosophical Transactions on the 'evolutionary ecology of arthropod antimicrobial peptides'. We see five interesting topics emerging. (i) AMP genes in insects, and perhaps in arthropods more generally, evolve much slower than most other immune genes. One explanation refers to the constraints set by AMPs being part of a finely tuned defence system. A new view argues that AMPs are under strong stabilizing selection. Regardless, this striking observation still invites many more questions than have been answered so far. (ii) AMPs almost always are expressed in combinations and sometimes show expression patterns that are dependent on the infectious agent. While it is often assumed that this can be explained by synergistic interactions, such interactions have rarely been demonstrated and need to be studied further. Moreover, how to define synergy in the first place remains difficult and needs to be addressed. (iii) AMPs play a very important role in mediating the interaction between a host and its mutualistic or commensal microbes. This has only been studied in a very small number of (insect) species. It has become clear that the very same AMPs play different roles in different situations and hence are under concurrent selection. (iv) Different environments shape the physiology of organisms; especially the host-associated microbial communities should impact on the evolution host AMPs. Studies in social insects and some organisms from extreme environments seem to support this notion, but, overall, the evidence for adaptation of AMPs to a given environment is scant. (v) AMPs are considered or already developed as new drugs in medicine. However, bacteria can evolve resistance to AMPs. Therefore, in the light of our limited understanding of AMP evolution in the natural context, and also the very limited understanding of the evolution of resistance against AMPs in bacteria in particular, caution is recommended. What is clear though is that study of the ecology and evolution of AMPs in natural systems could inform many of these outstanding questions, including those related to medical applications and pathogen control.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'.
Topics: Animals; Anti-Infective Agents; Antimicrobial Cationic Peptides; Arthropods; Evolution, Molecular; Gene Expression; Host-Pathogen Interactions; Immunity, Innate; Insect Proteins; Insecta; Selection, Genetic
PubMed: 27160599
DOI: 10.1098/rstb.2015.0297 -
Arthropod Structure & Development Jan 2017
Topics: Animals; Arthropods; Bedbugs; Chitinases; Developmental Biology; Drosophila melanogaster; Ecology; Insect Proteins; Macromolecular Substances; Models, Animal; Tribolium
PubMed: 28161051
DOI: 10.1016/j.asd.2017.01.004 -
The Journal of Experimental Biology Mar 2024Whether specific immune protection after initial pathogen exposure (immune memory) occurs in invertebrates has long been uncertain. The absence of antibodies, B-cells...
Whether specific immune protection after initial pathogen exposure (immune memory) occurs in invertebrates has long been uncertain. The absence of antibodies, B-cells and T-cells, and the short lifespans of invertebrates led to the hypothesis that immune memory does not occur in these organisms. However, research in the past two decades has supported the existence of immune memory in several invertebrate groups, including Ctenophora, Cnidaria, Nematoda, Mollusca and Arthropoda. Interestingly, some studies have demonstrated immune memory that is specific to the parasite strain. Nonetheless, other work does not provide support for immune memory in invertebrates or offers only partial support. Moreover, the expected biphasic immune response, a characteristic of adaptive immune memory in vertebrates, varies within and between invertebrate species. This variation may be attributed to the influence of biotic or abiotic factors, particularly parasites, on the outcome of immune memory. Despite its critical importance for survival, the role of phenotypic plasticity in immune memory has not been systematically examined in the past two decades. Additionally, the features of immune responses occurring in diverse environments have yet to be fully characterized.
Topics: Animals; Immunologic Memory; Invertebrates; Arthropods; Adaptation, Physiological; Antibodies
PubMed: 38449328
DOI: 10.1242/jeb.246158 -
Journal of Comparative Physiology. A,... Jul 2023The neural basis underlying spatial orientation in arthropods, in particular insects, has received considerable interest in recent years. This special issue of the...
The neural basis underlying spatial orientation in arthropods, in particular insects, has received considerable interest in recent years. This special issue of the Journal of Comparative Physiology A seeks to take account of these developments by presenting a collection of eight review articles and eight original research articles highlighting hotspots of research on spatial orientation in arthropods ranging from flies to spiders and the underlying neural circuits. The contributions impressively illustrate the wide range of tools available to arthropods extending from specific sensory channels to highly sophisticated neural computations for mastering complex navigational challenges.
Topics: Animals; Arthropods; Orientation, Spatial; Space Perception; Insecta; Spiders
PubMed: 37198448
DOI: 10.1007/s00359-023-01635-9 -
Pesticide Biochemistry and Physiology Jun 2015The recent accumulation of molecular studies on mutations in insects, ticks and mites conferring resistance to insecticides, acaricides and biopesticides is reviewed.... (Review)
Review
The recent accumulation of molecular studies on mutations in insects, ticks and mites conferring resistance to insecticides, acaricides and biopesticides is reviewed. Resistance is traditionally classified by physiological and biochemical criteria, such as target-site insensitivity and metabolic resistance. However, mutations are discrete molecular changes that differ in their intrinsic frequency, effects on gene dosage and fitness consequences. These attributes in turn impact the population genetics of resistance and resistance management strategies, thus calling for a molecular genetic classification. Mutations in structural genes remain the most abundantly described, mostly in genes coding for target proteins. These provide the most compelling examples of parallel mutations in response to selection. Mutations causing upregulation and downregulation of genes, both in cis (in the gene itself) and in trans (in regulatory processes) remain difficult to characterize precisely. Gene duplications and gene disruption are increasingly reported. Gene disruption appears prevalent in the case of multiple, hetero-oligomeric or redundant targets.
Topics: Acaricides; Animals; Arthropods; Drug Resistance; Genotype; Insecticides; Mutation; Phenotype
PubMed: 26047113
DOI: 10.1016/j.pestbp.2015.01.004 -
Integrative and Comparative Biology Nov 2015The handling and use of oxygen are central to physiological function of all pancrustaceans. Throughout the Pancrustacea, ventilation is controlled by a central... (Review)
Review
The handling and use of oxygen are central to physiological function of all pancrustaceans. Throughout the Pancrustacea, ventilation is controlled by a central oxygen-sensitive pattern generator. The ancestral condition was likely to achieve ventilation of the gills via leg-associated or mouth-associated muscles, but in insects and some air-breathing crustaceans, new muscles were recruited for this purpose, including intersegmental muscles likely used previously for posture and locomotion. Many aspects of the sensing of oxygen and the occurrence of responses to hypoxia (increased ventilation, depressed growth and metabolic rate, developmental changes that enhance the delivery of oxygen) appear common across most pancrustaceans, but there is tremendous variation across species. Some of this can be explained by habitat (e.g., ventilation of the internal medium occurs in terrestrial species and of the external medium in aquatic species; rearing under hypoxia induces tracheal proliferation in terrestrial insects and hemocyanin production in aquatic crustaceans); some plausibly by evolutionary origin of some responses to hypoxia within the Pancrustacea (the most basal arthropods may lack a ventilatory response to hypoxia); and some by the availability of environmental oxygen (animals adapted to survive hypoxia turn on the response to hypoxia at a lower PO2). On average, crustaceans and insects have similar tolerances to prolonged anoxia, but species or life stages from habitats with a danger of being trapped in hypoxia can tolerate longer durations of anoxia. Lactate is the primary anaerobic end-product in crustaceans but some insects have evolved a more diverse array of anaerobic end-products, including ethanol, alanine, succinate, and acetate. Most clades of Pancrustacea are small and lack obvious respiratory structures. Gilled stem-pancrustaceans likely evolved in the Cambrian, and gills persist in large Ostracoda, Malacostraca, and Branchiopoda. Based on currently accepted phylogenies, invaginations of cuticle to form lungs or tracheae occurred independently multiple times across the Arthropoda and Pancrustacea in association with the evolution of terrestriality. However, the timing and number of such events in the evolution of tracheal systems remain controversial. Despite molecular phylogenies that place the origin of the hexapods before the appearance of land plants in the Ordovician, terrestrial fossils of Collembola, Archaeognatha, and Zygentoma in the Silurian and Devonian, and the lack of fossil evidence for older aquatic hexapods, suggest that the tracheated hexapods likely evolved from Remipedia-like ancestors on land.
Topics: Animals; Biological Evolution; Crustacea; Insecta; Oxygen Consumption; Respiratory Physiological Phenomena
PubMed: 26002563
DOI: 10.1093/icb/icv055 -
Development Genes and Evolution Feb 2022Fox genes encode transcription factors that contain a DNA binding domain, the forkhead domain, and are known from diverse animal species. The exact homology of the Fox...
Fox genes encode transcription factors that contain a DNA binding domain, the forkhead domain, and are known from diverse animal species. The exact homology of the Fox genes of different species is debated and this makes inferences about the evolution of the Fox genes, and their duplications and losses difficult. We have performed phylogenetic analyses of the Fox gene complements of 32 panarthropod species. Our results confirm an ancestral complement of FoxA, FoxB, FoxC, FoxD, FoxF, FoxG, FoxJ1, FoxJ2/3, FoxK, FoxL1, FoxL2, FoxN1/4, FoxN2/3, FoxO, FoxP, and FoxQ2 in the Arthropoda, and additionally FoxH and FoxQ1 in the Panarthropoda (including tardigrades and onychophorans). We identify a novel Fox gene sub-family, that we designate as FoxT that includes two genes in Drosophila melanogaster, Circadianly Regulated Gene (Crg-1) and forkhead domain 3F (fd3F). In a very recent paper, the same new Fox gene sub-family was identified in insects (Lin et al. 2021). Our analysis confirms the presence of FoxT and shows that its members are present throughout Panarthropoda. We show that the hitherto unclassified gene CG32006 from the fly Drosophila melanogaster belongs to FoxJ1. We also detect gene losses: FoxE and FoxM were lost already in the panarthropod ancestor, whereas the loss of FoxH occurred in the arthropod ancestor. Finally, we find an ortholog of FoxQ1 in the bark scorpion Centruroides sculpturatus, confirmed not only by phylogenetic analysis, but also by forming an evolutionarily conserved gene cluster with FoxF, FoxC, and FoxL1. This suggests that FoxQ1 belongs to the ancestral Fox gene complement in panarthropods and also in chelicerates, but has been lost at the base of the mandibulate arthropods.
Topics: Animals; Arthropods; Drosophila melanogaster; Forkhead Transcription Factors; Phylogeny; Scorpions
PubMed: 35230523
DOI: 10.1007/s00427-022-00686-3 -
BMC Biology Jan 2022The evolution of the brain and its major neuropils in Panarthropoda (comprising Arthropoda, Tardigrada and Onychophora) remains enigmatic. As one of the closest...
BACKGROUND
The evolution of the brain and its major neuropils in Panarthropoda (comprising Arthropoda, Tardigrada and Onychophora) remains enigmatic. As one of the closest relatives of arthropods, onychophorans are regarded as indispensable for a broad understanding of the evolution of panarthropod organ systems, including the brain, whose anatomical and functional organisation is often used to gain insights into evolutionary relations. However, while numerous recent studies have clarified the organisation of many arthropod nervous systems, a detailed investigation of the onychophoran brain with current state-of-the-art approaches is lacking, and further inconsistencies in nomenclature and interpretation hamper its understanding. To clarify the origins and homology of cerebral structures across panarthropods, we analysed the brain architecture in the onychophoran Euperipatoides rowelli by combining X-ray micro-computed tomography, histology, immunohistochemistry, confocal microscopy, and three-dimensional reconstruction.
RESULTS
Here, we use this detailed information to generate a consistent glossary for neuroanatomical studies of Onychophora. In addition, we report novel cerebral structures, provide novel details on previously known brain areas, and characterise further structures and neuropils in order to improve the reproducibility of neuroanatomical observations. Our findings support homology of mushroom bodies and central bodies in onychophorans and arthropods. Their antennal nerve cords and olfactory lobes most likely evolved independently. In contrast to previous reports, we found no evidence for second-order visual neuropils, or a frontal ganglion in the velvet worm brain.
CONCLUSION
We imaged the velvet worm nervous system at an unprecedented level of detail and compiled a comprehensive glossary of known and previously uncharacterised neuroanatomical structures to provide an in-depth characterisation of the onychophoran brain architecture. We expect that our data will improve the reproducibility and comparability of future neuroanatomical studies.
Topics: Animals; Arthropods; Brain; Nervous System; Reproducibility of Results; X-Ray Microtomography
PubMed: 35073910
DOI: 10.1186/s12915-021-01196-w