-
Hormones and Behavior Jul 2020Almost fifty years ago the advent of assay methods to measure circulating levels of hormones revolutionized endocrinology in relation to investigations of free-living... (Review)
Review
Almost fifty years ago the advent of assay methods to measure circulating levels of hormones revolutionized endocrinology in relation to investigations of free-living and captive animals. This new field "environmental endocrinology" revealed that endocrine profiles in animals in their natural habitat were not only different from captive animals, but often deviated from predictions. It quickly became apparent that the organization and analysis of data from the field should be sorted by life history stages such as for reproductive processes, migration, molt etc. and spaced in time according to natural duration of those processes. Presentation of data by calendar date alone gives much simpler, even misleading, patterns. Stage-organized analyses revealed species-specific patterns of hormone secretion and dramatic inter-individual differences. The "Challenge Hypothesis" sparked exploration of these results, which diverged from expectations of hormone-behavior interactions. The hypothesis led to specific predictions about how the hypothalamo-pituitary-gonad axis, and particularly circulating patterns of testosterone, might respond to social challenges such as simulated territorial intrusions. Initially, a group of studies on free-living and captive birds played a key role in the formulation of the hypothesis. Over the decades since, the effects of social challenge and environmental context on hormonal responses have been tested in all vertebrate taxa, including humans, as well as in insects. Although it is now clear that the Challenge Hypothesis in its original form is simplistic, field and laboratory tests of the hypothesis have led to other concepts that have become seminal to the development of environmental endocrinology as a field. In this special issue these developments are addressed and examples from many different taxa enrich the emerging concepts, paving the way for investigations using recent technologies for genetic and transcriptome analyses.
Topics: Aggression; Animal Migration; Animals; Birds; Ecosystem; Endocrine System; Humans; Insecta; Male; Molting; Sexual Behavior, Animal; Social Environment; Species Specificity; Territoriality; Testosterone
PubMed: 31525343
DOI: 10.1016/j.yhbeh.2019.104588 -
Developmental and Comparative Immunology May 2016Crustacean hemocytes are important mediators of immune reactions, and the regulation of hemocyte homeostasis is of utmost importance for the health of these animals.... (Review)
Review
Crustacean hemocytes are important mediators of immune reactions, and the regulation of hemocyte homeostasis is of utmost importance for the health of these animals. This review discusses the current knowledge on the lineages, synthesis and differentiation of hemocytes in crustaceans. Hematopoietic tissues, their origins, and the regulation of hematopoiesis during molting, seasonal variation and infection are discussed. Furthermore, studies concerning the molecular regulation of hemocyte formation in crustaceans are also described, and the different lineages and their molecular markers are discussed and compared with several insect species. Signaling pathways and the regulation of hematopoiesis by transcription factors are typically conserved among these arthropods, whereas cytokines and growth factors are more variable and species specific. However, considering the great diversity among the crustaceans, one should be cautious in drawing general conclusions from studies of only a few species.
Topics: Animals; Crustacea; Cytokines; Hematopoiesis; Hemocytes; Homeostasis; Humans; Molting
PubMed: 26721583
DOI: 10.1016/j.dci.2015.12.009 -
Biology Letters Aug 2023Palaeoecological deductions are vital for understanding the evolution and diversification of species within prehistoric environments. This review highlights the... (Review)
Review
Palaeoecological deductions are vital for understanding the evolution and diversification of species within prehistoric environments. This review highlights the multitude of ways in which the microanatomy and microscopic structure of bones enables palaeoecological deductions. The occurrence of growth marks in bones is discussed, and their usefulness in deducing the ontogenetic status and age of individuals is considered, as well as how such marks in bones permit the assessment of the growth dynamics of individuals and species. Here osteohistology is shown to provide insight into the structure of past populations, as well as ecological relationships between individuals. In addition, the response of bones to trauma, disease and moulting is considered. Finally, I explore how osteohistology can give insight into ecomorphological adaptations, such as filter feeding, probe feeding and saltatorial locomotion. Methodological advances in three-dimensional microtomography and synchrotron scanning bodes well for future studies in osteohistology and despite some compromises in terms of tissue identity, circumvents the crucial issue of destructive analyses.
Topics: Humans; Locomotion; Molting
PubMed: 37607578
DOI: 10.1098/rsbl.2023.0245 -
Scientific Reports Jan 2023The ability of animals to sync the timing and location of molting (the replacement of hair, skin, exoskeletons or feathers) with peaks in resource availability has...
The ability of animals to sync the timing and location of molting (the replacement of hair, skin, exoskeletons or feathers) with peaks in resource availability has important implications for their ecology and evolution. In migratory birds, the timing and location of pre-migratory feather molting, a period when feathers are shed and replaced with newer, more aerodynamic feathers, can vary within and between species. While hypotheses to explain the evolution of intraspecific variation in the timing and location of molt have been proposed, little is known about the genetic basis of this trait or the specific environmental drivers that may result in natural selection for distinct molting phenotypes. Here we take advantage of intraspecific variation in the timing and location of molt in the iconic songbird, the Painted Bunting (Passerina ciris) to investigate the genetic and ecological drivers of distinct molting phenotypes. Specifically, we use genome-wide genetic sequencing in combination with stable isotope analysis to determine population genetic structure and molting phenotype across thirteen breeding sites. We then use genome-wide association analysis (GWAS) to identify a suite of genes associated with molting and pair this with gene-environment association analysis (GEA) to investigate potential environmental drivers of genetic variation in this trait. Associations between genetic variation in molt-linked genes and the environment are further tested via targeted SNP genotyping in 25 additional breeding populations across the range. Together, our integrative analysis suggests that molting is in part regulated by genes linked to feather development and structure (GLI2 and CSPG4) and that genetic variation in these genes is associated with seasonal variation in precipitation and aridity. Overall, this work provides important insights into the genetic basis and potential selective forces behind phenotypic variation in what is arguably one of the most important fitness-linked traits in a migratory bird.
Topics: Animals; Molting; Genome-Wide Association Study; Songbirds; Passeriformes; Feathers; Seasons
PubMed: 36646769
DOI: 10.1038/s41598-022-26973-7 -
Frontiers in Endocrinology 2021A pair of Y-organs (YOs) are the molting glands of decapod crustaceans. They synthesize and secrete steroid molting hormones (ecdysteroids) and their activity is... (Review)
Review
A pair of Y-organs (YOs) are the molting glands of decapod crustaceans. They synthesize and secrete steroid molting hormones (ecdysteroids) and their activity is controlled by external and internal signals. The YO transitions through four physiological states over the molt cycle, which are mediated by molt-inhibiting hormone (MIH; basal state), mechanistic Target of Rapamycin Complex 1 (mTORC1; activated state), Transforming Growth Factor-β (TGFβ)/Activin (committed state), and ecdysteroid (repressed state) signaling pathways. MIH, produced in the eyestalk X-organ/sinus gland complex, inhibits the synthesis of ecdysteroids. A model for MIH signaling is organized into a cAMP/Ca-dependent triggering phase and a nitric oxide/cGMP-dependent summation phase, which maintains the YO in the basal state during intermolt. A reduction in MIH release triggers YO activation, which requires mTORC1-dependent protein synthesis, followed by mTORC1-dependent gene expression. TGFβ/Activin signaling is required for YO commitment in mid-premolt. The YO transcriptome has 878 unique contigs assigned to 23 KEGG signaling pathways, 478 of which are differentially expressed over the molt cycle. Ninety-nine contigs encode G protein-coupled receptors (GPCRs), 65 of which bind a variety of neuropeptides and biogenic amines. Among these are putative receptors for MIH/crustacean hyperglycemic hormone neuropeptides, corazonin, relaxin, serotonin, octopamine, dopamine, allatostatins, Bursicon, ecdysis-triggering hormone (ETH), CCHamide, FMRFamide, and proctolin. Contigs encoding receptor tyrosine kinase insulin-like receptor, epidermal growth factor (EGF) receptor, and fibroblast growth factor (FGF) receptor and ligands EGF and FGF suggest that the YO is positively regulated by insulin-like peptides and growth factors. Future research should focus on the interactions of signaling pathways that integrate physiological status with environmental cues for molt control.
Topics: Animals; Decapoda; Ecdysteroids; Gene Expression Regulation; Insect Proteins; Molting; Signal Transduction
PubMed: 34234741
DOI: 10.3389/fendo.2021.674711 -
Journal of Morphology Nov 2016Crustaceans are a morphologically, physiologically, and ecologically highly diverse animal group and correspondingly diverse are their reproductive characteristics. They... (Review)
Review
Crustaceans are a morphologically, physiologically, and ecologically highly diverse animal group and correspondingly diverse are their reproductive characteristics. They have evolved structural specialties with respect to penis construction, sperm form, sperm storage, fertilization, and brood care. Unique in the animal kingdom are safety lines that safeguard hatching and first molting. Further curiosities are dwarf males in parasitic and sessile crustaceans and bacteria-induced feminization and gigantism of crustacean hosts. Record-breaking features are relative penis length, sperm size, clutch size, chromosome number, viability of dormant eggs, and fossil ages of penis, sperm, and brooded embryos. These examples from a single invertebrate subphylum and a single life history aspect illustrate that morphological solutions to functional requirements can be as spectacular as behavioral adaptations. They may provide valuable sources for comparative morphologists, ecologists, evolutionary biologists, and applied biologists to advance topical issues such as sperm competition, posthumous paternity, evolution of brood care, adaptation to freshwater, infectious feminization, sustainable male-based fishery, maintenance of genetic diversity under conditions of limited mating opportunity, and long-term impact of pollution on genotype and phenotype. J. Morphol. 277:1399-1422, 2016. © 2016 Wiley Periodicals, Inc.
Topics: Adaptation, Physiological; Animal Structures; Animals; Crustacea; Female; Male; Molting; Reproduction; Sexual Behavior, Animal
PubMed: 27454749
DOI: 10.1002/jmor.20582 -
The Journal of Steroid Biochemistry and... Jan 2019Arthropods have long been utilized as models to explore molecular function, and the findings derived from them can be applied throughout metazoa, including as a basis... (Review)
Review
Arthropods have long been utilized as models to explore molecular function, and the findings derived from them can be applied throughout metazoa, including as a basis for medical research. This has led to the adoption of many representative insect models beyond Drosophila, as each lends its own unique perspective to questions in endocrinology and genetics. However, non-insect arthropods are yet to be realised for the potential insight they may provide in such studies. The Crustacea are among the most ancient arthropods from which insects descended, comprising a huge variety of life histories and ecological roles. Of the events in a typical crustacean development, metamorphosis is perhaps the most ubiquitous, challenging and highly studied. Despite this, our knowledge of the endocrinology which underpins metamorphosis is rudimentary at best; although several key molecules have been identified and studied in depth, the link between them is quite nebulous and leans heavily on well-explored insect models, which diverged from the Pancrustacea over 450 million years ago. As omics technologies become increasingly accessible, they bring the prospect of explorative molecular research which will allow us to uncover components and pathways unique to crustaceans. This review reconciles known components of crustacean metamorphosis and reflects on our findings in insects to outline a future search space, with focus given to the ecdysone cascade. To expand our knowledge of this ubiquitous endocrine system not only aids in our understanding of crustacean metamorphosis, but also provides a deeper insight into the adaptive capacity of arthropods throughout evolution.
Topics: Animals; Crustacea; Ecdysone; Endocrine System; Insecta; Models, Animal; Molting
PubMed: 30157455
DOI: 10.1016/j.jsbmb.2018.08.012 -
General and Comparative Endocrinology Aug 2020Endocrine control of molting in decapod crustaceans involves the eyestalk neurosecretory center (X-organ/sinus gland complex), regenerating limbs, and a pair of Y-organs... (Review)
Review
Endocrine control of molting in decapod crustaceans involves the eyestalk neurosecretory center (X-organ/sinus gland complex), regenerating limbs, and a pair of Y-organs (YOs), as molting is induced by eyestalk ablation or multiple leg autotomy and suspended in early premolt by limb bud autotomy. Molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH), produced in the X-organ/sinus gland complex, inhibit the YO. The YO transitions through four physiological states over the molt cycle: basal in intermolt; activated in early premolt; committed in mid- and late premolt; and repressed in postmolt. We assembled the first comprehensive YO transcriptome over the molt cycle in the land crab, Gecarcinus lateralis, showing that as many as 23 signaling pathways may interact in controlling ecdysteroidogenesis. A proposed model of the MIH/cyclic nucleotide pathway, which maintains the basal YO, consists of cAMP/Ca triggering and nitric oxide (NO)/cGMP summation phases. Mechanistic target of rapamycin (mTOR) signaling is required for YO activation in early premolt and affects the mRNA levels of thousands of genes. Transforming Growth Factor-β (TGFβ)/Activin signaling is required for YO commitment in mid-premolt and high ecdysteroid titers at the end of premolt may trigger YO repression. The G. lateralis YO expresses 99 G protein-coupled receptors, three of which are putative receptors for MIH/CHH. Proteomic analysis shows the importance of radical oxygen species scavenging, cytoskeleton, vesicular secretion, immune response, and protein homeostasis and turnover proteins associated with YO function over the molt cycle. In addition to eyestalk ganglia, MIH mRNA and protein are present in brain, optic nerve, ventral nerve cord, and thoracic ganglion, suggesting that they are secondary sources of MIH. Down-regulation of mTOR signaling genes, in particular Ras homolog enriched in brain or Rheb, compensates for the effects of elevated temperature in the YO, heart, and eyestalk ganglia in juvenile Metacarcinus magister. Rheb expression increases in the activated and committed YO. These data suggest that mTOR plays a central role in mediating molt regulation by physiological and environmental factors.
Topics: Animals; Brachyura; Hormones; Molting; Proteomics; Signal Transduction; Transcriptome
PubMed: 32339519
DOI: 10.1016/j.ygcen.2020.113493 -
Marine Drugs Mar 2021Chitin is among the most important components of the crustacean cuticular exoskeleton and intestinal peritrophic matrix. With the progress of genomics and sequencing... (Review)
Review
Chitin is among the most important components of the crustacean cuticular exoskeleton and intestinal peritrophic matrix. With the progress of genomics and sequencing technology, a large number of gene sequences related to chitin metabolism have been deposited in the GenBank database in recent years. Here, we summarized the genes and pathways associated with the biosynthesis and degradation of chitins in crustaceans based on genomic analyses. We found that chitin biosynthesis genes typically occur in single or two copies, whereas chitin degradation genes are all multiple copies. Moreover, the chitinase genes are significantly expanded in most crustacean genomes. The gene structure and expression pattern of these genes are similar to those of insects, albeit with some specific characteristics. Additionally, the potential applications of the chitin metabolism genes in molting regulation and immune defense, as well as industrial chitin degradation and production, are also summarized in this review.
Topics: Animals; Chitin; Chitinases; Crustacea; Genomics; Molting
PubMed: 33804177
DOI: 10.3390/md19030153 -
British Poultry Science Oct 20221. Moulting is a natural physiological process in birds when they shed their old feathers and replace them with new ones, and it is followed by reproductive quiescence... (Review)
Review
1. Moulting is a natural physiological process in birds when they shed their old feathers and replace them with new ones, and it is followed by reproductive quiescence resulting in reduced egg production. Different birds undergo moulting at different points in their life. Some birds have seasonal moulting while some moult at the end of their breeding cycle. This review will mainly focus on moulting practices associated with commercial layer birds because, in all other bird types, this is not managed.2. Commercial farms commonly analyse the cost-benefit ratio to decide the time and method to adopt for moulting. Commercial layer farms adopt different practices to force birds out of moult and restart the production cycle. Animal welfare groups consider this as stressful and against animal welfare, raising questions about the ethics of this practice.3. Many studies have been conducted using complete or partial feed withdrawal and non-feed withdrawal programs to measure their effectiveness in maintaining animal welfare, economy, and post-moult performance in mind.4. Animal welfare should not be compromised during moulting. The United States Egg Producers and other such groups from the United Kingdom and Europe have decided to sell eggs produced only through a non-feed withdrawal moulting programs.
Topics: Animals; Female; Molting; Chickens; Ovum; Feathers; Reproduction
PubMed: 35363112
DOI: 10.1080/00071668.2022.2059339