Fig 3 - uploaded by Jerome Hui
Content may be subject to copyright.
A schematic diagram showing the sesquiterpenoid biosynthetic pathways in arthropods (modified from Bellés et al. 2005; Hui et al. 2010, 2013). (This figure is available in black and white in print and in color at Integrative and Comparative Biology online.)
Source publication
Arthropods are the most successful group of animals, and are found in diverse habitats; they account for more than 80% of described animal species. A rigid exoskeleton is a common feature that is shared across the different groups of arthropods. The exoskeleton offers protection and is shed between developmental stages via a unique evolutionarily c...
Contexts in source publication
Context 1
... The conserved mevalonate pathway existed in the bilater- ian ancestor in the Ordovician period (440-500 mya), and the biosynthetic pathway of arthropods diverged from that of vertebrates at the step cata- lyzed by farnesyl-PP ( Clark and Bloch 1959;Tobe and Bendena 1999;Bellés et al. 2005;Hui et al 2010Hui et al , 2013Nouzova et al. 2011; Fig. 3). In arthro- pods, farnesyl-PP is further modified to farnesol and farnesal because arthropods lack the enzymes squa- lene synthetase (farnesyl-diphosphate farnesyltrans- ferase) and lanosterol synthase, which are required for the production of cholesterol (Clark and Bloch 1959). These two compounds are important sex pheromones in ...
Context 2
... of the biosynthesis of JH. However, the order of the final two steps is depen- dent on the particular order of insect. In Orthoptera, Dictyoptera, Coleoptera, and Diptera, FA undergoes methylation of the carboxyl group to produce MF, which is subsequently epoxidized to generate JH-III. In Lepidoptera, however, epoxidation precedes meth- ylation (Fig. 3). In short, arthropods have developed a pathway uniquely different from the bilaterian ancestral mevalonate pathway for the biosynthesis of esquiter- penoid. The arthropod ancestor probably developed the ability to biosynthesize sesquiterpenoids in the form of FA and MF, and JH subsequently arose in the ancestor of ...
Similar publications
With a view to using the centipede Eupolybothrus nudicornis as a bioindicator in biomonitoring programs we studied the effects of environmental pollution on the activity of the enzyme acetylcholinesterase (AChE) as neurotoxicity marker. Males and females were collected during the spring breeding season at two sites located in the eastern part of Al...
Ecdysteroids are the principal steroid hormones of arthropods, regulating different physiological functions such as growth, metamorphosis and reproduction. Radioimmunoassay indicates the accumulation of ecdysteroids into the ovary during maturation of a sand crab Emerita asiatica. These ecdysteroids are sequestered from the hemolymph during the ent...
The copepod Calanus sinicus Brodsky dominates the zooplankton in the Yellow Sea, China, and undergoes over-summering within the Yellow Sea Cold Water Mass (YSCWM). Termination of over-summering and subsequent development are regarded as key processes in population recruitment, and are probably linked to environmental variations in the YSCWM. In thi...
The insect cuticle is composed of various proteins and formed during the moult under a complex biological process that depends on the cross talk between hormone levels and gene expression. In the present study, we aimed to clarify the ecdysone-dependent temporal regulation mechanisms of cuticular proteins expression and the underlying control of Bo...
The development of the adult optic lobe (OL) ofDrosophila melanogasteris directed by a wave of ingrowth of the photoreceptors over a two day period at the outset of metamorphosis which is accompanied by the appearance of the pupal-specific transcription factor Broad-Z3 (Br-Z3) and expression of early drivers in OL neurons. During this time, there a...
Citations
... This process involved the most drastic morphological change in the life cycle of copepods, which could partly influence the high sensitivity of this endpoint to toxicants. Although the hormone regulation of metamorphosis in copepods is still not fully understood, several studies suggest that this process is controlled by the "juvenile hormones" in conjunction with the actions of ecdysteroids, as known from insects and other crustaceans (Cheong et al., 2015;Laufer et al., 1988;Rodríguez et al., 2007). Certain pollutants, including additives from conventional plastics and synthetic rubber, can cause endocrine disruption in crustaceans (Rodríguez et al., 2007). ...
... Borovsky et al., 1994;Shinoda and Itoyama, 2003). Additionally, the last precursors have been reported to have per se regulatory function in development, metamorphosis, and reproduction (Cheong et al., 2015;De Loof et al., 2015). Pioneer works on the activity of purified compound in Rodnius (Schmialek, 1961;Wigglesworth, 1961) and on functional screening using Galleria wax test already showed the diverse characteristics of JH-like activity of farnesyl derivatives and related compounds (Schneiderman et al., 1965). ...
... The robust crustacean exoskeleton of arthropods serves as a formidable shield, affording them exceptional protection against challenging environmental conditions (Cheong et al. 2015). However, the exoskeleton also constrains the growth and development of arthropods, and they must undergo periodic molting to complete development and maturation. ...
The nuclear receptor gene Ecdysone-induced protein 75 (E75), as the component of ecdysone response genes in the ecdysone signaling pathway, has important regulatory function for insect molting. However, the regulatory function of E75 during the molting process of spider mites is not yet clear. In this study, the expression pattern of E75 in the molting process of the spider mite Tetranychus urticae was analyzed. The results showed that there was a peak at 8 h post-molting, followed by a decline 8 h after entering each respective quiescent stage across various developmental stages. During the deutonymph stage, the expression dynamics of E75, observed at 4-h intervals, indicated that the transcript levels of TuE75 peaked at 24 h, coinciding with the onset of molting in the mites. To investigate the function of TuE75 during the molting process, silencing TuE75 through dsRNA injection into deutonymph mites at the age of 8 h yielded a notable outcome: 78% of the deutonymph mites were unable to progress to the adult stage. Among these phenotypic mites, 37% were incapable of transitioning into the quiescent state and eventually succumbed after a certain period. An additional 41% of the mites successfully entered the quiescent state but encountered difficulties in shedding the old epidermis, leading to eventual mortality. In summary, these results suggested that TuE75 plays a key role in the molting process of T. urticae.
... A significant portion of initial hypotheses for their roles in crustaceans were taken from research of insect CYP450s, as the closest evolutionary relatives with characteristic similarity, however there are also significant differences between crustaceans and insects [7]. This variation is exemplified in the functionally conserved CYP450s named shade in insects and shed in crustaceans; the different naming is owing to their conserved function albeit distinct phylogeny [2]. 2 Conserved CYP450s in crustaceans are involved in ecdysteroidogenesis, the enzymatic pathway which generates the moult hormones [8]. Moulting is used by arthropods, including insects and crustaceans, to allow for growth and morphological changes [9]. ...
Cytochrome P450s (CYP450s) are a versatile superfamily of enzymes known to undergo rapid evolution. They have important roles across growth and development pathways in crustaceans, although it is difficult to characterise orthologs between species due to their sequence diversity. Conserved CYP450s enzymes in crustaceans are those associated with ecdysteroidogenesis; synthesising and breaking down the active moult hormone, 20-hydroxyecdysone. The complex life-cycle of the ornate spiny lobster, Panulirus ornatus, relies on moulting in order to grow and develop. Many of these diverse life stages have been analysed to establish a comprehensive transcriptomic database for this species. The transcripts putatively encoding for CYP450s were mapped using transcriptomic analysis and identified across growth and development stages. With the aid phylogeny, 28 transcripts of 42 putative P. ornatus CYP450s were annotated, including the well conserved Halloween genes, which are involved in ecdysteroidogenesis. Expression patterns across the life-stages determined that only a subset of the CYP450s can be detected in each life-stage or tissue. Four Shed transcripts show overlapping expression between metamorphosis and adult tissues, suggesting pleotropic functions of the multiple Shed orthologs within P. ornatus.
... The process of elimination of the exoskeleton is known as molting/ecdysis and is triggered by steroid hormones, ecdysteroids, with the contribution of juvenile hormones, sesquiterpenes in nature, and neuropeptides. [2][3][4]. ...
:Chitin is the second most
widespread polysaccharide in nature after cellulose
and is mainly found in the world of invertebrate
animals. Its function is protective and structural and
it is present in the exoskeleton of arthropods,
insects, while it is absent in vertebrates. Chitin is
also found in the plant kingdom, as a cellulose
substituent, in the cell membrane of many fungi,
lichens and bacteria. It is insoluble in water, dilute
acids and alkalis; it can be partially deacetylated,
transforming into its derivative, chitosan, with
promising application properties.
In insects, chitin is a material that acts as a scaffold,
supporting the cuticles of the epidermis and
trachea, as well as the peritrophic matrices that line
the intestinal epithelium.
The growth and morphogenesis of insects are
closely dependent on the ability to remodel chitin�containing structures, and to achieve this, insects
continuously produce different enzymes in various
tissues. During their development and growth, it is
important to coordinate the processes of chitin
synthesis and degradation under the control of the
enzymes involved in the process.
Little research has been performed on the
extraction and characterization of chitin present in
insects, as previous studies have focused on chitin
and chitosan present in crustaceans. Currently,
many properties of these substances have been
highlighted and research has been increased for
application in various sectors such as food,
medical, cosmetics and biomaterials engineering.
... Our findings suggest that molting mites are less susceptible to ivermectin than motile mites. This might be attributed to the outer cuticle which offers protection to the mites [16,17]. In the present study, the LC 50 for ivermectin against female mites at 1h was 84.1 μM, which is higher than the values reported in previous studies (50.5 μM and 45.1 μM) [18,19]. ...
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.
... Initiation of development is induced when sensory neurons detect the filling of the cuticle by insect tissues that reach a critical size [118]. Responses to this signal will then involve three major groups of hormones [119]. First, neurosecretory cells in the brain release neuropeptides such as prothoracicotropic hormone (PITH). ...
Insect sequential development evolves from a simple molt towards complete metamorphosis. Like any multicellular host, insects interact with a complex microbiota. In this review, factors driving the microbiota dynamics were pointed out along their development. Special focus was put on tissue renewal, shift in insect ecology, and microbial interactions. Conversely, how the microbiota modulates its host development through nutrient acquisition, hormonal control, and cellular or tissue differentiation was exemplified. Such modifications might have long-term carry-over effects on insect physiology. Finally, remarkable microbe-driven control of insect behaviors along their life cycle was highlighted. Increasing knowledge of those interactions might offer new insights on how insects respond to their environment as well as perspectives on pest- or vector-control strategies.
... As a corollary, however, the benefit of the arthropod exoskeleton as a barrier to ion and water movements is temporally interrupted at regular intervals, since arthropods must molt to grow (Cheong et al. 2015). During pre-molt, increased osmotic permeability and resultant water influx leads to swelling and ecdysis, enabling the discontinuous growth of an everlarger individual during the early post-molt (Freire et al. 2013). ...
Early marine invertebrates like the Branchiopoda began their sojourn into dilute media some 500 million years ago in the Middle Cambrian. Others like the Mollusca, Annelida, and many crustacean taxa have followed, accompanying major marine transgressions and regressions, shifting landmasses, orogenies, and glaciations. In adapting to these events and new habitats, such invertebrates acquired novel physiological abilities that attenuate the ion loss and water gain that constitute severe challenges to life in dilute media. Among these taxon-specific adaptations, selected from the subcellular to organismal levels of organization, and constituting a feasible evolutionary blueprint for invading freshwater, are reduced body permeability and surface (S) to volume (V) ratios, lowered osmotic concentrations, increased osmotic gradients, increased surface areas of interface epithelia, relocation of membrane proteins in ion-transporting cells, and augmented transport enzyme abundance, activity, and affinity. We examine these adaptations in taxa that have penetrated into freshwater, revealing diversified modifications, a consequence ofdistinct body plans, morpho-physiological resources, and occupation routes. Contingent on life history and reproductive strategy, numerous patterns of osmotic regulation have emerged, including intracellular isosmotic regulation in weak hyper-regulators and well-developed anisosmotic extracellular regulation in strong hyper-regulators, likely reflecting inertial adaptations to early life in an estuarine environment. In this review, we address osmoregulation in those freshwater invertebrate lineages that have successfully invaded this biotope. Our analyses show that across 66 freshwater invertebrate species from six phyla/classes that have transmuted into freshwater from the sea, hemolymph osmolalities decrease logarithmically with increasing S:V ratios, particularly among the Arthropoda. The arthropods show the highest osmolalities, from 300 to 650 mOsmoles/kg H2O in the Decapoda with 220–320 mOsmoles/kg H2O in the Insecta; osmolalities in the Annelida range from 150 to 200 mOsmoles/kg H2O, and the Mollusca showing the lowest osmolalities at 40–120 mOsmoles/kg H2O.Overall, arthropod osmolalities reach a cut-off at ∼200 mOsmoles/kg H2O, independently of increasing S:V ratio. The ability of species with small S:V ratios to maintain large osmotic gradients is mirrored in their putatively higher Na+/K+-ATPase activities that drive ion uptake processes. Selection pressures on these morpho-physiological characteristics have led to differential osmoregulatory abilities, rendering possible the conquest of freshwater while retaining some tolerance of the ancestral medium.
... Like other arthropods, myriapods possess a rigid chitinous exoskeleton that offers protection and prevents water loss. This exoskeleton is moulted periodically during ecdysis under the regulation of endocrine factors, including sesquiterpenoid hormones 6 . ...
... We also compare the content and organisation of developmentally relevant genes and pathways between centipedes and millipedes, to examine their respective roles in myriapod evolution. In particular, we consider homeobox genes, the content and organisation of which can have profound impacts on animal phenotypes 13 , and hormonal pathways which regulate arthropod development 6 . Collectively, our findings significantly expand current knowledge of the myriapod genomics, and provide novel insights into the evolution of genome size, gene repertoire, and genetic pathways across myriapod diversity. ...
Animals display a fascinating diversity of body plans. Correspondingly, genomic analyses have revealed dynamic evolution of gene gains and losses among animal lineages. Here we sequence six new myriapod genomes (three millipedes, three centipedes) at key phylogenetic positions within this major but understudied arthropod lineage. We combine these with existing genomic resources to conduct a comparative analysis across all available myriapod genomes. We find that millipedes generally have considerably smaller genomes than centipedes, with the repeatome being a major contributor to genome size, driven by independent large gains of transposons in three centipede species. In contrast to millipedes, centipedes gained a large number of gene families after the subphyla diverged, with gains contributing to sensory and locomotory adaptations that facilitated their ecological shift to predation. We identify distinct horizontal gene transfer (HGT) events from bacteria to millipedes and centipedes, with no identifiable HGTs shared among all myriapods. Loss of juvenile hormone O-methyltransferase, a key enzyme in catalysing sesquiterpenoid hormone production in arthropods, was also revealed in all millipede lineages. Our findings suggest that the rapid evolution of distinct genomic pathways in centipede and millipede lineages following their divergence from the myriapod ancestor, was shaped by differing ecological pressures. Myriapods play an important ecological role in soil and forest ecosystems. Here the authors analyse nine myriapod genomes, showing rapid evolution of distinct genomic pathways in centipede and millipede lineages, shaped by differing ecological pressures.
... Hormones are important regulators of animal development and play important roles in both physiology and body plan diversification during animal evolution [1,2]. Sesquiterpenes are a class of terpenes that consist of three isoprene units, and a sesquiterpenoid hormone named juvenile hormone (JH) is precisely controlled for their titers, together with ecdysteroid, in the processes of complete and incomplete metamorphosis of insects (i.e., holometabolous and hemimetabolous) [1,3,4]. ...
... Hormones are important regulators of animal development and play important roles in both physiology and body plan diversification during animal evolution [1,2]. Sesquiterpenes are a class of terpenes that consist of three isoprene units, and a sesquiterpenoid hormone named juvenile hormone (JH) is precisely controlled for their titers, together with ecdysteroid, in the processes of complete and incomplete metamorphosis of insects (i.e., holometabolous and hemimetabolous) [1,3,4]. In brief, JH binds to intracellular receptor, Methoprene-tolerant (Met) and triggers the expression of downstream genes, including Kruppel homolog 1 (Kr-h1), that regulate development and metamorphosis in insects [5][6][7] (Figure 1). ...
... The biosynthesis of JH has long known to be specific to insects since its discovery in the 1930s by Vincent Wigglesworth [1,6,23,27]. Different insects are now known to have different sesquiterpenoid biosynthetic pathways and modified products [7]. ...
The sesquiterpenoid hormone juvenile hormone (JH) controls development, reproduction, and metamorphosis in insects, and has long been thought to be confined to the Insecta. While it remains true that juvenile hormone is specifically synthesized in insects, other types or forms of sesquiterpenoids have also been discovered in distantly related animals, such as the jellyfish. Here, we combine the latest literature and annotate the sesquiterpenoid biosynthetic pathway genes in different animal genomes. We hypothesize that the sesquiterpenoid hormonal system is an ancestral system established in an animal ancestor and remains widespread in many animals. Different animal lineages have adapted different enzymatic routes from a common pathway, with cnidarians producing farnesoic acid (FA); non-insect protostomes and non-vertebrate deuterostomes such as cephalochordate and echinoderm synthesizing FA and methyl farnesoate (MF); and insects producing FA, MF, and JH. Our hypothesis revolutionizes the current view on the sesquiterpenoids in the metazoans, and forms a foundation for a re-investigation of the roles of this important and yet neglected type of hormone in different animals.
