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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 -
General and Comparative Endocrinology Dec 2021Crustacean Y-organs secrete ecdysteroid molting hormones. Ecdysteroids are released in increased amount during premolt, circulate in hemolymph, and stimulate the events... (Review)
Review
Crustacean Y-organs secrete ecdysteroid molting hormones. Ecdysteroids are released in increased amount during premolt, circulate in hemolymph, and stimulate the events in target cells that lead to molting. During much of the molting cycle, ecdysteroid production is suppressed by molt-inhibiting hormone (MIH), a peptide neurohormone produced in the eyestalks. The suppressive effect of MIH is mediated by a cyclic nucleotide second messenger. A decrease in circulating MIH is associated with an increase in the hemolymphatic ecdysteroid titer during pre-molt. Nevertheless, it has long been hypothesized that a positive regulatory signal or stimulus is also involved in promoting ecdysteroidogenensis during premolt. Data reviewed here are consistent with the hypothesis that an intracellular Ca signal provides that stimulus. Pharmacological agents that increase intracellular Ca in Y-organs promote ecdysteroidogenesis, while agents that lower intracellular Ca or disrupt Ca signaling suppress ecdysteroidogenesis. Further, an increase in the hemolymphatic ecdysteroid titer after eyestalk ablation or during natural premolt is associated with an increase in intracellular free Ca in Y-organ cells. Several lines of evidence suggest elevated intracellular calcium is linked to enhanced ecdysteroidogenesis through activation of Ca/calmodulin dependent cyclic nucleotide phosphodiesterase, thereby lowering intracellular cyclic nucleotide second messenger levels and promoting ecdysteroidogenesis. Results of transcriptomic studies show genes involved in Ca signaling are well represented in Y-organs. Several recent studies have focused on Ca transport proteins in Y-organs. Complementary DNAs encoding a plasma membrane Ca ATPase (PMCA) and a sarcoplasmic/endoplasmic reticulum Ca ATPase (SERCA) have been cloned from crab Y-organs. The relative abundance of PMCA and SERCA transcripts in Y-organs is elevated during premolt, a time when Ca levels in Y-organs are likewise elevated. The results are consistent with the notion that these transport proteins act to maintain the Ca gradient across the cell membrane and re-set the cell for future Ca signals.
Topics: Animals; Brachyura; Calcium Signaling; Ecdysteroids; Hemolymph; Invertebrate Hormones; Molting
PubMed: 34530000
DOI: 10.1016/j.ygcen.2021.113901 -
Insect Biochemistry and Molecular... Jan 2023Digestion and absorption of old cuticles during insect molting are necessary for new cuticle formation, during which complicated enzyme catalysis is essential. To date,...
Digestion and absorption of old cuticles during insect molting are necessary for new cuticle formation, during which complicated enzyme catalysis is essential. To date, a few carboxypeptidases, aminopeptidases and serine proteases (mostly trypsins) connected with cuticle digestion, zymogen activation and histological differentiation during the ecdysis of lepidopteran, dipteran and hymenopteran insects have been identified. However, little is known about these proteins in hemimetabolous insects. In this study, we identified 33 candidate trypsin and trypsin-like homologs, 14 metallocarboxypeptidase and 32 aminopeptidase genes in the brown planthopper Nilaparvata lugens, a hemipteran rice pest. Among the proteins encoded by these genes, 9 trypsin-like proteases, 3 metallocarboxypeptidases and 1 aminopeptidase were selected as potential procuticle hydrolases by bioinformatics analysis and in vivo validation. RNA interference targeting these genes demonstrated that 3 trypsin-like proteases (NlTrypsin-8, NlTrypsin-29 and NlTrypsin-32) genes and 1 metallocarboxypeptidase (NlCpB) gene were found to be essential for ecdysis in N. lugens; specifically, gene silencing led to incomplete cuticle degradation and arrested ecdysis, causing lethal morphological phenotype acquisition. Spatiotemporal expression profiling by quantitative PCR and western blotting revealed their specific expression in the integument and their periodic expression during each stadium, with a peak before ecdysis and eclosion. Transmission electron microscopy demonstrated corresponding ultrastructural defects after RNAi targeting, with NlCpB-silenced specimens having the most undigested old procuticles. Immunohistochemical staining revealed that NlTrypsin-8, NlTrypsin-29 and NlCpB were predominantly located in the exuvial space. This research further adds to our understanding of proteases and its potential role in insect ecdysis.
Topics: Animals; Trypsin; Molting; Hemiptera; Serine Proteases; RNA Interference; Aminopeptidases; Insect Proteins
PubMed: 36513274
DOI: 10.1016/j.ibmb.2022.103893 -
Comparative Biochemistry and... Oct 2023Crustacean molting is highly related to energy and lipid metabolism. This study was conducted to detect the changes of total lipids (TL), triacylglyceride (TAG),...
Crustacean molting is highly related to energy and lipid metabolism. This study was conducted to detect the changes of total lipids (TL), triacylglyceride (TAG), phospholipid (PL) and lipid droplets in hepatopancreas, and then to investigate the gene expression patterns related to hepatopancreatic lipid metabolism during the molting cycle of Chinese mitten crab Eriocheir sinensis. Hepatopancreatic TL and TAG increased significantly from post-molt stage to pre-molt stage, then decreased significantly from pre-molt stage to ecdysis stage, which is consistent to the changes of neutral lipid-rich adipocytes in hepatopancreas. By transcriptomic analysis, 65,325 transcripts were sequenced and assembled, and 28,033 transcripts were annotated. Most genes were related to energy metabolism, and the enriched genes were involved in carbohydrate and lipid metabolism and biosynthesis, especially in de novo synthesis of fatty acids and TAG, and ketone body production. Compared to the inter-molt stages, acetyl-CoA carboxylase, fatty acid synthase and other genes related to the synthesis of fatty acids were upregulated in the pre-molt stage. TAG synthesis related genes, including Glycerol-3-phosphate acyltransferase and 1-acylglycerol-3-phosphate acyltransferases, were upregulated in the post-molt stage compared to the inter-molt stage. The expression of ketone body-related genes had no significant changes during the molting cycle. Compared to the TAG synthetic pathway, ketone body biosynthesis may contribute less/secondarily to fatty acid metabolic processes, which could be involved in the other physiological processes or metabolism. In conclusion, these results showed that TAG is the major lipid deposition during inter- and pre-molt stages, and the most genes are related to the fatty acids and TAG metabolism in the hepatopancreas during the molting cycle of E. sinensis.
Topics: Animals; Transcriptome; Molting; Lipid Metabolism; Fatty Acids; Phosphates; Ketones; Brachyura; Hepatopancreas
PubMed: 37406959
DOI: 10.1016/j.cbpa.2023.111474 -
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 -
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 -
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 -
Hormones and Behavior Feb 2017Bacteria have had a fundamental impact on vertebrate evolution not only by affecting the evolution of the immune system, but also generating complex interactions with... (Review)
Review
Bacteria have had a fundamental impact on vertebrate evolution not only by affecting the evolution of the immune system, but also generating complex interactions with behavior and physiology. Advances in molecular techniques have started to reveal the intricate ways in which bacteria and vertebrates have coevolved. Here, we focus on birds as an example system for understanding the fundamental impact bacteria have had on the evolution of avian immune defenses, behavior, physiology, reproduction and life histories. The avian egg has multiple characteristics that have evolved to enable effective defense against pathogenic attack. Microbial risk of pathogenic infection is hypothesized to vary with life stage, with early life risk being maximal at either hatching or fledging. For adult birds, microbial infection risk is also proposed to vary with habitat and life stage, with molt inducing a period of increased vulnerability. Bacteria not only play an important role in shaping the immune system as well as trade-offs with other physiological systems, but also for determining digestive efficiency and nutrient uptake. The relevance of avian microbiomes for avian ecology, physiology and behavior is highly topical and will likely impact on our understanding of avian welfare, conservation, captive breeding as well as for our understanding of the nature of host-microbe coevolution.
Topics: Animals; Biological Evolution; Birds; Breeding; Ecosystem; Life Cycle Stages; Microbiota; Molting; Reproduction
PubMed: 28065710
DOI: 10.1016/j.yhbeh.2016.12.003 -
Arthropod Structure & Development Jan 2017Comparative ultrastructural studies of the integument in terrestrial isopod crustaceans show that specific environmental adaptations of different eco-morphotypes are... (Review)
Review
Comparative ultrastructural studies of the integument in terrestrial isopod crustaceans show that specific environmental adaptations of different eco-morphotypes are reflected in cuticle structure. The biphasic molting in isopods is a valuable experimental model for studies of cuticular matrix secretion and degradation in the same animal. The aim of this review is to show structural and functional adaptations of the tergal cuticle in terrestrial isopods inhabiting cave habitats. Exoskeletal cuticle thickness, the number of cuticular layers, epicuticle structure, mineralization, pigmentation and complexity of sensory structures are compared, with greater focus on the well-studied cave trichoniscid Titanethes albus. A large number of thinner cuticular layers in cave isopods compared to fewer thicker cuticular layers in related epigean species of similar body-sizes is explained as a specific adaptation to the cavernicolous life style. The epicuticle structure and composition are compared in relation to their potential waterproofing capacity in different environments. Cuticle mineralization is described from the functional point of view as well as from the aspect of different calcium storage sites and calcium dynamics during the molt cycle. We also discuss the nature and reduction of pigmentation in the cave environment and outline perspectives for future research.
Topics: Adaptation, Physiological; Animal Shells; Animals; Calcification, Physiologic; Calcium; Caves; Ecosystem; Insect Proteins; Isopoda; Molting; Oxygen Consumption; Pigmentation; Species Specificity
PubMed: 27502824
DOI: 10.1016/j.asd.2016.08.002 -
Biological Reviews of the Cambridge... Apr 2019Although feathers are the unifying characteristic of all birds, our understanding of the causes, mechanisms, patterns and consequences of the feather moult process lags... (Review)
Review
Although feathers are the unifying characteristic of all birds, our understanding of the causes, mechanisms, patterns and consequences of the feather moult process lags behind that of other major avian life-history phenomena such as reproduction and long-distance migration. Migration, which evolved in many species of the temperate and arctic zones, requires high energy expenditure to endure long-distance journeys. About a third of Western-Palearctic passerines perform long-distance migrations of thousands of kilometres each year using various morphological, physiological, biomechanical, behavioural and life-history adaptations. The need to include the largely non-overlapping breeding, long-distance migration and feather moult processes within the annual cycle imposes a substantial constraint on the time over which the moult process can take place. Here, we review four feather-moult-related adaptations which, likely due to time constraints, evolved among long-distance Western-Palearctic migrants: (i) increased moult speed; (ii) increased overlap between moult and breeding or migration; (iii) decreased extent of plumage moult; and (iv) moult of part or all of the plumage during the over-wintering period in the tropics rather than in the breeding areas. We suggest that long-distance migration shaped the evolution of moult strategies and increased the diversity of these strategies among migratory passerines. In contrast to this variation, all resident passerines in the Western Palearctic moult immediately after breeding by renewing the entire plumage of adults and in some species also juveniles, while in other species juvenile moult is partial. We identify important gaps in our current understanding of the moult process that should be addressed in the future. Notably, previous studies suggested that the ancestral moult strategy is a post-breeding summer moult in the Western Palearctic breeding areas and that moult during the winter evolved due to the scheduling of long-distance migration immediately after breeding. We offer an alternative hypothesis based on the notion of southern ancestry, proposing that the ancestral moult strategy was a complete moult during the 'northern winter' in the Afro-tropical region in these species, for both adults and juveniles. An important aspect of the observed variation in moult strategies relates to their control mechanisms and we suggest that there is insufficient knowledge regarding the physiological mechanisms that are involved, and whether they are genetically fixed or shaped by environmental factors. Finally, research effort is needed on how global climate changes may influence avian annual routines by altering the scheduling of major processes such as long-distance migration and feather moult.
Topics: Age Factors; Analysis of Variance; Animal Migration; Animals; Biological Evolution; Breeding; Climate; Feathers; Female; Male; Molting; Passeriformes; Seasons; Sex Factors; Time Factors
PubMed: 30334341
DOI: 10.1111/brv.12474