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Current Biology : CB Sep 2020Feather molt is an important life-history process in birds, but little is known about its evolutionary history. Here, we report on the first fossilized evidence of...
Feather molt is an important life-history process in birds, but little is known about its evolutionary history. Here, we report on the first fossilized evidence of sequential wing feather molt, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather molt patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the molt period. Therefore, we conclude that flight was essential for either its daily foraging or escaping from predators. Our findings propose that the development of sequential molt is the outcome of evolutionary forces to maintain flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 mya. VIDEO ABSTRACT.
Topics: Animals; Dinosaurs; Ecosystem; Feathers; Flight, Animal; Molting; Wings, Animal
PubMed: 32679101
DOI: 10.1016/j.cub.2020.06.046 -
Proceedings. Biological Sciences May 2018Birds and mammals have developed numerous strategies for replacing worn feathers and hair. Moulting usually occurs on an annual basis; however, moults that take place... (Review)
Review
Birds and mammals have developed numerous strategies for replacing worn feathers and hair. Moulting usually occurs on an annual basis; however, moults that take place twice per year (biannual moults) also occur. Here, we review the forces driving the evolution of various moult strategies, focusing on the special case of the complete biannual moult as a convergence of selection pressures across birds and mammals. Current evidence suggests that harsh environmental conditions or seasonality (e.g. larger variation in temperatures) drive evolution of a biannual moult. In turn, the biannual moult can respond to secondary selection that results in phenotypic alteration such as colour changes for mate choice dynamics (sexual selection) or camouflage requirements (natural selection). We discuss the contributions of natural and sexual selection to the evolution of biannual moulting strategies in the contexts of energetics, niche selection, functionality and physiological mechanisms. Finally, we suggest that moult strategies are directly related to species niche because environmental attributes drive the utility (e.g. thermoregulation, camouflage, social dynamics) of the hair or feathers. Functional efficiency of moult may be undermined if the pace of evolution fails to match that of the changing climate. Thus, future research should seek to understand the plasticity of moult duration and phenology, especially in the context of annual cycles.
Topics: Animals; Biological Evolution; Birds; Feathers; Hair; Mammals; Molting
PubMed: 29769361
DOI: 10.1098/rspb.2018.0318 -
Hormone-related genes heterochronically and modularly regulate neotenic differentiation in termites.Developmental Biology May 2022Caste development in social insects requires the coordination of molting and metamorphosis during postembryonic development. In termites, i.e., hemimetabolous eusocial...
Caste development in social insects requires the coordination of molting and metamorphosis during postembryonic development. In termites, i.e., hemimetabolous eusocial insects, caste fate is determined during postembryonic development. However, it is not fully understood how the mechanisms of molting/metamorphosis are regulated in the course of differentiation between reproductive and sterile castes. In termites, only reproductives derived from alates are imagos and other sterile castes (including developmentally-terminal soldier caste) are basically juveniles or nymphs. Furthermore, supplementary reproductives that appear when the original queens and kings die or become senescent, exhibit larval features such as winglessness, and are called neotenics. Therefore, the question of whether neotenics are larvae or imagos is still under debate. In this study, by inducing female neotenic differentiation in a damp-wood termite Hodotermopsis sjostedti, morphological investigations together with juvenile hormone (JH) quantification and expression/functional analyses of genes responsible for molting and/or metamorphosis were carried out. JH titer and expression of one of the downstream genes (Kr-h1) were shown to be temporarily lowered, but increased just prior to the molt into neotenics, while consistently lowered in imaginal molt (i.e., alate differentiation). In contrast, ecdysone-related genes (EcR and E93) were upregulated at both neotenic and alate differentiation, suggesting that the heterochronic actions of ecdysone and JH lead the neotenic differentiation. Moreover, expression analyses, supported by reverse genetic experiments, showed that EcR and E93 were specifically upregulated in genital sternites (EcR and E93) and ovaries (E93) and required for the development of imaginal characters. These results suggest that the resultant mosaic phenotype of female neotenics is due to modular responses of different body parts to hormonal actions.
Topics: Animals; Ecdysone; Female; Isoptera; Juvenile Hormones; Molting; Sex Differentiation
PubMed: 35248548
DOI: 10.1016/j.ydbio.2022.02.012 -
Scientific Reports Jul 2022Termite castes express specialized phenotypes for their own tasks and are a good example of insect polyphenism. To understand the comprehensive gene expression profiles...
Termite castes express specialized phenotypes for their own tasks and are a good example of insect polyphenism. To understand the comprehensive gene expression profiles during caste differentiation, RNA-seq analysis based on the genome data was performed during the worker, presoldier, and nymphoid molts in Reticulitermes speratus. In this species, artificial induction methods for each molt have already been established, and the time scale has been clarified. Three different periods (before the gut purge (GP), during the GP, and after the molt) were discriminated in each molt, and two body parts (head and other body regions) were separately sampled. The results revealed that many differentially expressed genes (head: 2884, body: 2579) were identified in each molt. Based on the independent real-time quantitative PCR analysis, we confirmed the different expression patterns of seven out of eight genes in the presoldier molt. Based on the GO and KEGG enrichment analyses, the expressions of genes related to juvenile hormone titer changes (e.g., JH acid methyltransferase), nutrition status (e.g., Acyl-CoA Delta desaturase), and cell proliferation (e.g., insulin receptor), were shown to specifically fluctuate in each molt. These differences may have a crucial impact on caste differentiation. These data are important resources for future termite sociogenomics.
Topics: Animals; Isoptera; Juvenile Hormones; Molting; Transcriptome
PubMed: 35831400
DOI: 10.1038/s41598-022-15984-z -
Scientific Reports Aug 2022Trilobite exuviae record the development of individual trilobites and their molting process and can also contain information on their behavior. The silt- to fine-grained...
Trilobite exuviae record the development of individual trilobites and their molting process and can also contain information on their behavior. The silt- to fine-grained tuffites of the middle part of the Middle Member of the Upper Devonian Hongguleleng Formation in western Junggar contains abundant phacopidae trilobite, specifically Omegops sp. A, almost all of which are exuviae. Based on the preservation pattern, burial environment, and set of organisms co-occurring with Omegops sp. A, we speculate that the environment represented by the middle part of the Middle Member of the Hongguleleng Formation served only as the molting site of Omegops sp. A, and that their primary habitat was elsewhere. Omegops sp. A would have thus travelled to deep-water to molt. The reasons for allopatric molting may have included avoiding predators and interference from competing organisms during molting. This implies that the migratory behavior of some modern arthropods may have existed since at least the Devonian. This behavior suggests that Late Devonian phacopidae trilobites may have migrated to deeper water expanded their ecological domain as a survival strategy in response to unfavorable ecological environment.
Topics: Animals; Arthropods; Fossils; Molting; Preservation, Biological; Water
PubMed: 35974064
DOI: 10.1038/s41598-022-18146-3 -
Scientific Reports Aug 2020Molt is a critical developmental process in crustaceans. Recent studies have shown that the hepatopancreas is an important source of innate immune molecules, yet...
Molt is a critical developmental process in crustaceans. Recent studies have shown that the hepatopancreas is an important source of innate immune molecules, yet hepatopancreatic patterns of gene expression during the molt cycle which may underlie changes in immune mechanism are unknown. In this study, we performed Illumina sequencing for the hepatopancreas of the mud crab, Scylla paramamosain during molt cycle (pre-molt stage, post-molt stage, and inter-molt stage). A total of 44.55 Gb high-quality reads were obtained from the normalized cDNA of hepatopancreas. A total of 70,591 transcripts were assembled; 55,167 unigenes were identified. Transcriptomic comparison revealed 948 differentially expressed genes (DEGs) in the hepatopancreas from the three molt stages. We found that genes associated with immune response patterns changed in expression during the molt cycle. Antimicrobial peptide genes, inflammatory response genes, Toll signaling pathway factors, the phenoloxidase system, antioxidant enzymes, metal-binding proteins and other immune related genes are significantly up-regulated at the post-molt stage and inter-molt stage compared with the pre-molt stage, respectively. These genes are either not expressed or are expressed at low levels at the pre-molt stage. To our knowledge, this is the first systematic transcriptome analysis of genes capable of mobilizing a hepatopancreas immune response during the molt cycle in crustaceans, and this study will contribute to a better understanding of the hepatopancreas immune system and mud crab prophylactic immune mechanisms at the post-molt stage.
Topics: Animals; Brachyura; Gene Expression Profiling; Hepatopancreas; Molting
PubMed: 32753724
DOI: 10.1038/s41598-020-70139-2 -
PLoS Neglected Tropical Diseases May 2023Sarcoptes scabiei is a permanent obligate ectoparasite that lives and reproduces in the epidermis of humans and other mammals worldwide. There is a lack of information...
BACKGROUND
Sarcoptes scabiei is a permanent obligate ectoparasite that lives and reproduces in the epidermis of humans and other mammals worldwide. There is a lack of information on the molting process of Sarcoptes scabiei. Ivermectin is widely used to treat Sarcoptes infection in humans and animals, while the survival of molting Sarcoptes mites in the presence of ivermectin is unknown. The aim of the present study is to investigate the molting process of Sarcoptes mites and assess the activity of ivermectin during the molting process of Sarcoptes mites.
METHODOLOGY/PRINCIPAL FINDINGS
molting Sarcoptes mites were incubated at 35°C and 80% relative humidity and observed hourly until complete molt. Of the 192 molting mites recorded, the longest molt periods for larvae and nymphs were 23 and 30 h, respectively. The activity of ivermectin on molting Sarcoptes mites was also assessed using two concentrations of the drug (0.1 and 0.05 mg/ml). The exposure time for molting mites was determined by 100% mortality of female mites exposed to the solution of ivermectin. While all female mites were killed after exposure to 0.1 mg/ml ivermectin for 2 h and and 0.05 mg/ml for 7 h, 32% and 36% of molting mites survived and successfully molted, respectively.
CONCLUSIONS/SIGNIFICANCE
The present study demonstrated that molting Sarcoptes mites are less susceptible to ivermectin than active mites. As a consequence, mites may survive after two doses of ivermectin given 7 days apart due not only to hatching eggs but also to the resistance of mites during their molting process. Our results provide insight into the optimal therapeutic regimens for scabies and highlight the need for further research on the molting process of Sarcoptes mites.
Topics: Animals; Humans; Female; Ivermectin; Sarcoptes scabiei; Molting; Scabies; Mammals
PubMed: 37196006
DOI: 10.1371/journal.pntd.0011337 -
Poultry Science Jun 2003Feed deprivation has been adopted by the commercial egg industry to induce molt because it is the easiest method to apply and produces the best results. Feed... (Review)
Review
Feed deprivation has been adopted by the commercial egg industry to induce molt because it is the easiest method to apply and produces the best results. Feed deprivation, however, raises concerns about animal welfare. Birds respond to long-term feed deprivation in three phases. The first phase lasts at most a few days, during which physiological and behavioral adjustments ultimately reduce protein catabolism and energy expenditure. A temporary increase in plasma corticosterone may be observed at this time. Corticosterone promotes gluconeogenesis, helping to maintain plasma glucose levels in the initial stage of the fast. The corticosterone increase may also be linked to increased activity in feed-deprived birds. Hens have been observed to manifest temporarily increased levels of alertness and activity during the first 48 h of feed deprivation. Aggressive behavior of hens also has been observed to increase briefly during the first day of feed deprivation. The second phase is the longest, during which proteins are spared and lipids are catabolized to provide energy. This phase may last several months in some species; in the chicken it can continue more than 20 d. Hens show increasing amounts of resting behavior during this phase. The third phase begins when protein catabolism accelerates. A pathological stage eventually is reached when the bird will cease activity and no longer eat. The phased response to feed deprivation optimizes a tradeoff between the need to maintain constant levels of plasma glucose to sustain activity and the need to preserve critical body structures such as muscles and organs. Hens are capable of vigorous activity throughout feed deprivation periods typical of induced molts, which do not appear to take birds beyond the second phase of fasting. Hens having undergone extended fasts may also have improved livability. Alternative induced molting methods are being sought to reduce animal welfare concerns. The methods of current interest involve alteration of feeding regimen and cause at least some body weight loss. These alternative methods should be evaluated to ensure that they do not actually make aspects of hen welfare worse compared to feed withdrawal, which might happen if hens perceive feed restriction without being allowed to progress fully into the second phase of adaptation to feed deprivation.
Topics: Aggression; Animal Feed; Animal Husbandry; Animal Welfare; Animals; Attention; Behavior, Animal; Chickens; Corticosterone; Female; Food Deprivation; Glucose; Molting; Weight Loss
PubMed: 12817455
DOI: 10.1093/ps/82.6.992 -
Frontiers in Immunology 2022Molting is one of the most important biological processes of crustacean species, and a number of molecular mechanisms facilitate this complex procedure. However, the...
Molting is one of the most important biological processes of crustacean species, and a number of molecular mechanisms facilitate this complex procedure. However, the understanding of the immune mechanisms underlying crustacean molting cycle remains very limited. This study performed transcriptome sequencing in hemolymph and hepatopancreas of the swimming crab () during the four molting stages: post-molt (AB), inter-molt (C), pre-molt (D), and ecdysis (E). The results showed that there were 78,572 unigenes that were obtained in the hemolymph and hepatopancreas of . Further analysis showed that 98 DEGs were involved in immunity response of hemolymph and hepatopancreas, and most of the DEGs participated in the process of signal transduction, pattern recognition proteins/receptors, and antioxidative enzymes system. Specifically, the key genes and pathway involved in signal transduction including the , , , three genes in mitogen-activated protein kinase (MAPK) signaling cascade (, , and ), and four genes in Toll pathway (, , , and ). For the pattern recognition proteins/receptors, the lowest expression level of 11 genes was found in the E stage, including , and in the hemolymph, and hepatopancreatic , , , , , and . Moreover, the expression level of , , , , , and in stage C or stage D significantly higher than that of stage E or stage AB. These results fill in the gap of the continuous transcriptional changes that are evident during the molting cycle of crab and further provided valuable information for elucidating the molecular mechanisms of immune regulation during the molting cycle of crab.
Topics: Animals; Brachyura; Transcriptome; Molting; Swimming; Down Syndrome; Biological Phenomena; Lectins, C-Type; Integrins; Cell Adhesion Molecules
PubMed: 36389847
DOI: 10.3389/fimmu.2022.1037739 -
Communications Biology Jul 2023Feathers are a primitive trait among pennaraptoran dinosaurs, which today are represented by crown birds (Neornithes), the only clade of dinosaurs to survive the end... (Review)
Review
Feathers are a primitive trait among pennaraptoran dinosaurs, which today are represented by crown birds (Neornithes), the only clade of dinosaurs to survive the end Cretaceous mass extinction. Feathers are central to many important functions and therefore, maintaining plumage function is of great importance for survival. Thus, molt - by which new feathers are formed to replace old ones, is an essential process. Our limited knowledge regarding molt in early pennaraptoran evolution is based largely on a single Microraptor specimen. A survey of 92 feathered non-avian dinosaur and stem bird fossils did not find additional molting evidence. Due to its longer duration, in ornithological collections evidence of molt is found more frequently in extant bird species with sequential molts compared to those with more rapid simultaneous molts. The low frequency of molt occurrence among fossil specimens resembles collections of bird species with simultaneous molts. The dearth of molt evidence in the forelimbs of pennaraptoran specimens may have interesting implications regarding molt strategy during early avian evolution, and suggests that the yearly molting cycle may have evolved later, among crown birds.
Topics: Animals; Dinosaurs; Phylogeny; Molting; Fossils; Wings, Animal; Birds
PubMed: 37400509
DOI: 10.1038/s42003-023-05048-x