Cyanobacterial Protease Inhibitor Microviridin J Causes a Lethal Molting Disruption in Daphnia pulicaria

Laboratory experiments identified microviridin J as the source of a fatal molting disruption in Daphnia species organisms feeding on Microcystis cells. The molting disruption was presumably linked to the inhibitory effect of microviridin J on daphnid proteases, suggesting that hundreds of further cyanobacterial protease inhibitors must be considered potentially toxic to zooplankton.     

Effects of nutrient and light availability on production of bioactive anabaenopeptins and microviridin by the cyanobacterium <Emphasis Type="Italic">Planktothrix agardhii</Emphasis>

Cyanobacteria produce a large number of bioactive oligopeptides with yet unknown functions. Here the effect of environmental factors on the production of two anabaenopeptins and a microviridin by Planktothrix agardhii was investigated. The results were compared with previous findings on the production of a third family of oligopeptides, the highly toxic microcystins, to test the hypothesis that environmental factors affect the production of different types of cyanobacterial bioactive oligopeptides in a similar manner. Despite marked changes in culture conditions, variations in the amount of cell-bound anabaenopeptins and microviridin I per biomass unit did not exceed a factor of 5. High amounts of cell-bound anabaenopeptins and microviridin I per Planktothrix biovolume were associated with a high availability of nitrogen and phosphorus. The production of anabaenopeptins and microviridin continued as long as the Planktothrix cultures grew. In all cases the oligopeptide net production rate was linearly correlated to the growth rate of Planktothrix, identifying the growth activity as a major regulator of anabaenopeptin and microviridin production. The concentration of anabaenopeptins and microviridins in nature may therefore be estimated from the biomass concentration of their producers. These findings are similar to those previously reported for microcystins and thus support the idea that different types of bioactive cyanobacterial oligopeptides may share common regulation patterns. This may be seen as a hint to a mutual function of cyanobacterial oligopeptides, although further studies are needed to draw final conclusions on this issue. Handling editor: J. Padisak     

Impacts of xenobiotics on crustacean molting: the invisible endocrine disruption

Aquatic pollution has led to the accumulation of various xenobioticsin crustaceans. A number of these environmental chemicals havebeen found to interfere with molting of crustaceans. Resultsof initial mechanistic studies with Uca pugilator suggest thatthe disruption of molting results from the disturbance to theY-organ-ecdysteroid receptor (EcR) axis by xenobiotics. Suchdisturbance to the Y-organ-EcR axis can be caused by interferencewith epidermal ecdysteroid signaling and/or alterations in ecdysteroidogenesisand/or ecdysteroid disposition. Because the adverse impactson crustacean molting cannot be readily seen in the wild, thedisruption of molting represents an invisible form of endocrinedisruption.     

Exploiting the Natural Diversity of Microviridin Gene Clusters for Discovery of Novel Tricyclic Depsipeptides

Microviridins are ribosomally synthesized tricyclic depsipeptides produced by different genera of cyanobacteria. The prevalence of the microviridin gene clusters and the natural diversity of microviridin precursor sequences are currently unknown. Screening of laboratory strains and field samples of the bloom-forming freshwater cyanobacterium Microcystis via PCR revealed global occurrence of the microviridin pathway and an unexpected natural variety. We could detect 15 new variants of the precursor gene mdnA encoding microviridin backbones that differ in up to 4 amino acid positions from known isoforms of the peptide. The survey not only provides insights into the versatility of the biosynthetic enzymes in a closely related group of cyanobacteria, but also facilitates the discovery and characterization of cryptic microviridin variants. This is demonstrated for microviridin L in Microcystis aeruginosa strain NIES843 and heterologously produced variants.Bloom-forming freshwater cyanobacteria are a rich source of natural products (30). They flourish in lakes and ponds of different temperate zones, where they can eventually form thick scums at the surface. Microcystis is one of the predominant genera composing these blooms, particularly in lakes suffering from eutrophication (17). Like other bloom-forming species, it is infamous for the production of the hepatotoxin microcystin, a nonribosomal peptide toxin that inhibits protein phosphatases in a broad range of eukaryotes from zooplankton to humans (1, 9). Moreover, Microcystis is known to produce a multitude of other peptides that are considered to be potential drug leads (14, 30).Microviridins form one of the most intriguing classes of peptides, since they feature a cage-like structure (e.g., microviridin B) (Fig. ​(Fig.1A).1A). The highly unusual tricyclic architecture results from ω-ester and ω-amide bonds between amino acid side chains. The past few years have afforded 13 variants of the peptide from both field samples and laboratory strains (5, 8, 13, 15, 21, 22). Most of the variants show inhibitory activities against serine-type proteases, most notably against elastase, which is a target enzyme in the treatment of lung emphysema (28). One of the peptide isoforms, microviridin J, has been shown to inhibit the molting process of Daphnia, leading to death of the animals (23).Open in a separate windowFIG. 1.(A) Representative structure of microviridin B and three-dimensional model. (B) Schematic representation of the microviridin gene cluster of M. aeruginosa NIES298. The positions of primers for the amplification of mdnA, -B, and -C are indicated. GNAT, GCN5-related N-acetyltransferase. (C) PCR gel picture showing the amplification of mdnB from a selection of laboratory strains.Recent studies have revealed a unique biosynthetic mechanism for microviridins in Microcystis and the filamentous cyanobacterial genus Planktothrix (18, 31). The 14-amino-acid (aa) peptide sequence is encoded at the C terminus of the ribosomal precursor peptide MdnA (31). Macrocyclization of the peptide depends on the activities of two ATP grasp-type ligases, MdnB and -C, that are encoded downstream of the precursor gene. Further enzymes encoded by the cluster include the N-acetyltransferase MdnD and the putative transporter-peptidase MdnE (31) (Fig. ​(Fig.1B).1B). The activities of the enzymes MdnB, -C, and -D were confirmed by heterologous production of microviridins in Escherichia coli (31). The MdnB and -C orthologs of the filamentous cyanobacterial strain Planktothrix agardhii CYA126, MvdC and MvdD, were characterized using synthetic precursor peptides in vitro (18). Furthermore, Philmus et al. have shown limited flexibility of MvdD, catalyzing two rounds of microviridin lactonization to accept substrates with altered amino acid compositions and a stringent ring size requirement (19).Recent genome-sequencing projects with cyanobacteria have revealed widespread occurrence of microviridin-related gene clusters in various cyanobacterial genera, although the production of microviridins by these strains remains to be shown (18, 24, 31). Here, we present data showing an unprecedented natural diversity of microviridin precursor genes in a set of closely related Microcystis laboratory strains and field samples. The insights gained from our survey provide lessons about the flexibility of the microviridin ligases in a small group of cyanobacteria and an estimate of the size of the natural microviridin library that still awaits discovery. The detection of novel natural microviridin prepeptides from Microcystis can ultimately guide the heterologous production of novel microviridins in E. coli. As proof of principle, we have identified and characterized the new variant microviridin L from the strain Microcystis aeruginosa NIES843.     

Functional Analysis of Environmental DNA-Derived Microviridins Provides New Insights into the Diversity of the Tricyclic Peptide Family

Microviridins represent a unique family of ribosomally synthesized cage-like depsipeptides from cyanobacteria with potent protease-inhibitory activities. The natural diversity of these peptides is largely unexplored. Here, we describe two methodologies that were developed to functionally characterize cryptic microviridin gene clusters from metagenomic DNA. Environmental samples were collected and enriched from cyanobacterial freshwater blooms of different geographical origins containing predominantly Microcystis sp. Microviridins were produced either directly from fosmid clones or after insertion of environmental DNA-derived gene cassettes into a minimal expression platform in Escherichia coli. Three novel microviridin variants were isolated and tested against different serine-type proteases. The comparison of the bioactivity profiles of the new congeners allows deduction of further structure-function relationships for microviridins. Moreover, this study provides new insights into microviridin processing and gene cluster organization.     

Non-target effects of the insecticide methoprene on molting in the estuarine crustacean Neomysis integer (Crustacea: Mysidacea)

Ecdysteroids, the molting hormones in crustaceans and other arthropods, play a crucial role in the control of growth, reproduction and embryogenesis of these organisms. Insecticides are often designed to target specific endocrine-regulated functions such as molting and larval development such as methoprene, a juvenile hormone analogue.The aim of this study was to examine the effects of methoprene on molting in a non-target species, the estuarine mysid Neomysis integer (Crustacea: Mysidacea). Mysids have been proposed as standard test organisms for evaluating the endocrine disruptive effect of chemicals. Juveniles (< 24 h) were exposed for 3 weeks to the nominal concentrations 0.01, 1 and 100 μg methoprene/l. Daily, present molts were checked and stored in 4% formaldehyde for subsequent growth measurements. Methoprene significantly delayed molting at 100 μg/l by decreasing the growth rate and increasing the intermolt period. This resulted in a decreased wet weight of the organism. The anti-ecdysteroidal properties of methoprene on mysid molting were also evaluated by determining the ability of exogenously administered 20-hydroxyecdysone, the active ecdysteroid in crustaceans, to protect against the observed methoprene effects. Co-exposure to 20-hydroxyecdysone did not mitigate methoprene effects on mysid molting. This study demonstrates the need for incorporating invertebrate-specific hormone-regulated endpoints in regulatory screening and testing programs for the detection of endocrine disruption caused by man-made chemicals.     

THE EFFECT OF COLCHICINE ON MYOGENESIS IN VIVO IN RANA PIPIENS AND RHODNIUS PROLIXUS (HEMIPTERA)

The effect of colchicine on myogenesis in vivo has been studied in the regenerating tadpole tail of the frog, Rana pipiens, and in the abdominal molting muscles of a blood-sucking bug, Rhodnius prolixus Stål. Colchicine is shown to disrupt microtubules in the differentiating muscle cells of both these organisms. The disruption of microtubules is correlated with a loss of longitudinal anisometry in the myoblasts and myotubes of the regeneration blastema in the tadpole tail. Before colchicine treatment, the myotubes contain longitudinally oriented myofibrils. After colchicine treatment, rounded, multinucleate myosacs containing randomly oriented myofibrils are present. It is suggested that the primary function of microtubules in myogenesis in the Rana pipiens tadpole is the maintenance of cell shape. The abdominal molting muscles of Rhodnius undergo repeated phases of differentiation and dedifferentiation of the sarcoplasm. However, the longitudinal anisometry of the muscle fibers is maintained in all phases by the attachments of the ends of the fibers to the exoskeleton, and microtubule disruption does not alter cell shape. The orientation of the developing myofibrils is also unaltered, indicating that the microtubules do not directly align or support the myofibrils in this system.     

Physiological compensation in unilateral eyestalk ablated crayfish, Cherax quadricarinatus

The eyestalks of crustaceans contain neurosecretory cells involved in the regulation of molting. In crayfish, bilateral ablation results in increased molting frequency and weight gain whereas unilateral ablation typically has no effect on molting frequency and weight gain. The effects of unilateral ablation were examined in juvenile Australian freshwater crayfish, Cherax quadricarinatus. As observed for other crayfish species, molting frequency and weight gain of unilateral ablated crayfish were not significantly different from control (intact) crayfish. Survival of unilateral ablated crayfish, however, was reduced compared to controls and was likely due to stress associated with the surgical procedure itself. Using radiolabeling techniques, protein synthesis was determined for neural tissues from the remaining eyestalk of ablated crayfish and compared to protein synthesis of neural tissues from eyestalks of control, non-ablated crayfish. Protein synthesis of ablated crayfish neural tissues was significantly higher (ca. 45%) than protein synthesis of control neural tissues. Electrophoretic analysis (SDS-PAGE and autoradiography) further demonstrated that protein synthesis increased linearly for all proteins in the remaining eyestalk of ablated crayfish. Together, these results suggest that a compensatory response occurred in unilateral ablated crayfish allowing normal physiological functions, particularly those involved in regulating growth cycles, to be maintained. J. Exp. Zool. 289:184-189, 2001.     

Cloning and characterization of a new hetero-gene cluster of nonribosomal peptide synthetase and polyketide synthase from the cyanobacterium Microcystis aeruginosa K-139

Two nonribosomal peptide synthetase genes responsible for the biosynthesis of microcystin and micropeptin in Microcystis aeruginosa K-139 have been identified. A new nonribosomal peptide synthetase gene, psm3, was identified in M. aeruginosa K-139. The gene is a cluster extending 30 kb and comprising 13 bidirectionally transcribed open reading frames arranged in two putative operons. psm3 encodes four adenylation proteins, one polyketide synthase, and several unique proteins, especially Psm3L consisting of halogenase, acyl-CoA binding protein-like protein, and acyl carrier protein. Alignment of the binding pocket of the adenylation domain and an ATP-PPi exchange analysis using a recombinant protein with the adenylation domain of Psm3B showed that Psm3G and Psm3B activate aspartic acid and tyrosine, respectively. Although disruption of psm3 did not reveal the product produced by Psm3, we identified microviridin B and aeruginosin K139 in the cells of M. aeruginosa K-139. The above-mentioned results indicated that M. aeruginosa possesses at least five nonribosomal peptide synthetase gene clusters.     

Inhibition of cuticular lipid synthesis and its effect on insect survival

A new approach to insect control—using sodium trichloroacetate (NaTCA) to inhibit synthesis of the hydrophobic cuticular lipids that protect insects from dehydration—was tested on Triatoma infestans. In vivo and in vitro studies of incorporation of radioactive precursors showed diminished cuticular hydrocarbon synthesis after NaTCA treatment. Thin layer chromatography and scanning electron microscopy showed disruption of the cuticular lipid layer of NaTCA-treated insects, which also have increased mortality and altered molting cycles. NaTCA treatment enhanced the penetration and increased the lethality of a contact insecticide. © 1994 Wiley-Liss, Inc.     

Proteolytic activity in <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> PCC7806 is inhibited by a trypsin-inhibitory cyanobacterial peptide with a partial structure of microviridin

This paper describes the characterization of proteases in Microcystis aeruginosa PCC7806 cells being inhibited by a metabolite produced by another Microcystis strain, Microcystis Ku1. With casein and oligopeptide substrates and specific inhibitors we detected activity similar to bacterial serine endoproteases. Substrate SDS-polyacrylamide gel electrophoresis revealed the presence of nine bands of proteases (ca. 35∼125 kDa). The cyanobacterial enzymes were insensitive to endogenous trypsin-inhibitory metabolites. Microcystis Ku1 produced a metabolite, tentatively characterized as microviridin, inhibiting both cyanobacterial proteases and trypsin at an estimated IC₅₀ of, respectively, 2.2 and 9.0 μg mL⁻¹. On activity gels, inhibitors specific to animal trypsin and elastase and the putative microviridin led to an inactivation of the proteases associated with the 88 and 110 kDa bands. We hypothesize that in Microcystis populations there is a “cross-talk” between the inhibitors and the proteases, and only the colonies of identical chemotypes can possibly aggregate to form blooms.     

Completeness of seasonal molting in passerine birds (Aves,Passeriformes) in Northwestern Siberia

This paper considers the variability of the completeness of seasonal molting in passerine birds of the forest tundra and tundra areas of Western Siberia. All variants of passerine birds of North Eurasia known for molting—from complete postjuvenile molting at hatching places to its absence and complete postjuvenile molting at wintering places or at migratory routes, from complete prebreeding molting at wintering places to its absence, and from complete postbreeding molting at nesting places to complete molting at wintering places or at migratory routes—are shown. The factors affecting the completeness of molting are discussed—the properties of adaptation to the subarctic region, length of the migratory route, and photoperiodic conditions during molting. The completeness of molting is most significantly affected by the duration of daylight.     

MOLTING PHENOLOGY OF HARBOR SEALS ON TUGIDAK ISLAND, ALASKA

We documented the progression and timing of the annual molt of harbor seals on Tugidak Island, Alaska, from 1997 to 1999. In all years the timing of molting differed among age-sex classes. Yearlings molted first, subadults second, adult females third, and lastly adult males. Timing of molting was nearly identical in 1997–1998, whereas in 1999 molting occurred three to six days later for all age-sex classes except yearlings. Estimated dates when peak proportions of each age-sex class were molting ranged from 2 August (yearlings) to 2 September (adult males). The number of seals hauled out was positively related to the proportion of seals in the molt and negatively related to the proportion of seals in the postmolt. Population trend estimates, based on aerial counts conducted during a narrow window within the molting period, are likely biased toward certain age-sex classes. Statistical models used to estimate trend include covariates to help account for within-year variation in seal numbers, but do not account for compositional changes that occur during molting. Population modeling may elucidate the effects of within-year population structure on trend estimates. Monitoring molting phenology at additional sites is necessary to determine the extent of geographic variation in molting.     

Normal versus gamma: stochastic models of copepod molting rate

Molting rate is a key life history parameter in copepods. Sincecopepod population growth is an inherently exponential process,accurate formulation of molting rate is of critical importance.Many experiments have been conducted to culture different copepodspecies under varying temperatures and food concentrations.Probability density functions (PDFs) then were used to estimatethe median development time (MDT) of different copepod stagesfrom the experimental data. These MDTs are used in copepod populationmodels. Asymmetrical PDFs are widely used to model molting rate,because the shapes of these curves are similar to laboratorydata on cohort development. In this paper, we developed an individualstochastic model (ISM) to simulate the molting rate with differentPDFs. We showed that there was no connection between the asymmetryof cohorts and the asymmetry of the molting PDF. Although age-within-stagemodels have been widely used to simulate copepod populationdynamics, we found that none had used the correct formulationof molting rate. The population model requires the probabilityof molting at each time step, whereas the laboratory-derivedPDF is the frequency distribution of stage duration. Therefore,the PDF cannot be applied directly to the population model.We present here a corrected formula based on the PDF for usein copepod population models, termed the probability of moltingfor remaining individuals (PMR). Despite emphasis on use ofthe gamma function for copepod molting, we found simpler functionswork equally well, but that prior use of incorrect molting ratefunctions in copepod models can seriously overestimate generationtime.     

Biological surface coating and molting inhibition as mechanisms of TiO2 nanoparticle toxicity in Daphnia magna

The production and use of nanoparticles (NP) has steadily increased within the last decade; however, knowledge about risks of NP to human health and ecosystems is still scarce. Common knowledge concerning NP effects on freshwater organisms is largely limited to standard short-term (≤48 h) toxicity tests, which lack both NP fate characterization and an understanding of the mechanisms underlying toxicity. Employing slightly longer exposure times (72 to 96 h), we found that suspensions of nanosized (～100 nm initial mean diameter) titanium dioxide (nTiO(2)) led to toxicity in Daphnia magna at nominal concentrations of 3.8 (72-h EC(50)) and 0.73 mg/L (96-h EC(50)). However, nTiO(2) disappeared quickly from the ISO-medium water phase, resulting in toxicity levels as low as 0.24 mg/L (96-h EC(50)) based on measured concentrations. Moreover, we showed that nTiO(2) (～100 nm) is significantly more toxic than non-nanosized TiO(2) (～200 nm) prepared from the same stock suspension. Most importantly, we hypothesized a mechanistic chain of events for nTiO(2) toxicity in D. magna that involves the coating of the organism surface with nTiO(2) combined with a molting disruption. Neonate D. magna (≤6 h) exposed to 2 mg/L nTiO(2) exhibited a "biological surface coating" that disappeared within 36 h, during which the first molting was successfully managed by 100% of the exposed organisms. Continued exposure up to 96 h led to a renewed formation of the surface coating and significantly reduced the molting rate to 10%, resulting in 90% mortality. Because coating of aquatic organisms by manmade NP might be ubiquitous in nature, this form of physical NP toxicity might result in widespread negative impacts on environmental health.     

An essential role in molting and morphogenesis of Caenorhabditis elegans for ACN-1, a novel member of the angiotensin-converting enzyme family that lacks a metallopeptidase active site

Genome sequence analyses predict many proteins that are structurally related to proteases but lack catalytic residues, thus making functional assignment difficult. We show that one of these proteins (ACN-1), a unique multi-domain angiotensin-converting enzyme (ACE)-like protein from Caenorhabditis elegans, is essential for larval development and adult morphogenesis. Green fluorescent protein-tagged ACN-1 is expressed in hypodermal cells, the developing vulva, and the ray papillae of the male tail. The hypodermal expression of acn-1 appears to be controlled by nhr-23 and nhr-25, two nuclear hormone receptors known to regulate molting in C. elegans. acn-1(RNAi) causes arrest of larval development because of a molting defect, a protruding vulva in adult hermaphrodites, severely disrupted alae, and an incomplete seam syncytium. Adult males also have multiple tail defects. The failure of the larval seam cells to undergo normal cell fusion is the likely reason for the severe disruption of the adult alae. We propose that alteration of the ancestral ACE during evolution, by loss of the metallopeptidase active site and the addition of new protein modules, has provided opportunities for novel molecular interactions important for post-embryonic development in nematodes.     

Phenol oxidase is a necessary enzyme for the silkworm molting which is regulated by molting hormone

Insect molting is an important developmental process of metamorphosis, which is initiated by molting hormone. The molting process includes the activation of dermal cells, epidermal cells separation, molting fluid secretion, the formation of new epidermis and old epidermis excoriation etc. Polyphenol oxidases (PPOs), dopa decarboxylase and acetyltransferase are necessary enzymes for this process. Traditionally, the phenol oxidase was considered as an enzyme for epidermal layer’s tanning and melanization. This work suggested that polyphenol oxidases are one set of the key enzymes in molting, which closely related with the role of ecdysone in regulation of molting processes. The data showed that the expression peak of phenol oxidase in silkworm is higher during molting stage, and decreases after molting. The significant increase in the ecdysone levels of haemolymph was observed in the artificially fed silkworm larvae with ecdysone hormone. Consistently, the phenol oxidase expression was significantly elevated compared to the control. PPO1 RNAi induced phenol oxidase expression obviously declined in the silkworm larvae, and caused the pupae incomplete pupation. Overall, the results described that the phenol oxidase expression is regulated by the molting hormone, and is a necessary enzyme for the silkworm molting.     

The role of olfaction during mating in the southern temperate spiny lobster Jasus edwardsii

Chemosensory communication may be crucial during mate choice and mating in the southern temperate spiny lobster Jasus edwardsii to ensure that females mate with large males capable of supplying adequate numbers of sperm during the short mating window. To clarify the role of pheromones during this process, three laboratory experiments were carried out. In an experiment where the output of urine, which contains sex-specific pheromones, from large and small catheterized males was switched, large post-molt females did not make a clear choice of mate. This indicates that while females distinguish among females, males, and juveniles using their chemosensory sense, they distinguish among males using visual and tactile senses in combination with olfaction. Further, two antennule-ablation experiments were carried out to determine if detection of pheromones by the antennules of females or males was critical for mate selection, courting, or mating. In both cases, we observed a (nonsignificant) trend of slightly delayed mating of treatment females. We found that disruption of female olfaction causes less impact on courtship or mating than ablation of male antennules which increased the variance in the length of the period between molting and mating and resulted in a systematic reduction in clutch size. This lesser impact of female ablation may be because females can still respond to their own internal cues about egg ripeness whereas males cannot. In J. edwardsii, unlike the American clawed lobster, Homarus americanus, one fully functional partner of either sex appears sufficient to initiate mating.     

Functional Analysis of Insect Molting Fluid Proteins on the Protection and Regulation of Ecdysis

Molting fluid accumulates between the old and new cuticles during periodical ecdysis in Ecdysozoa. Natural defects in insect ecdysis are frequently associated with melanization (an immunity response) occurring primarily in molting fluids, suggesting that molting fluid may impact immunity as well as affect ecdysis. To address this hypothesis, proteomic analysis of molting fluids from Bombyx mori during three different types of ecdysis was performed. Many proteins were newly identified, including immunity-related proteins, in each molting fluid. Molting fluids inhibited the growth of bacteria in vitro. The entomopathogenic fungi Beauveria bassiana, which can escape immune responses in feeding larvae, is quickly recognized by larvae during ecdysis, followed by melanization in molting fluid and old cuticle. Fungal conidia germination was delayed, and no hyphae were detected in the hemocoels of pharate instar insects. Molting fluids protect the delicate pharate instar insects with extremely thin cuticles against microorganisms. To explore the function of molting fluids in ecdysis regulation, based on protein similarity, 32 genes were selected for analysis in ecdysis regulation through RNAi in Tribolium castaneum, a model commonly used to study integument development because RNAi is difficult to achieve in B. mori. We identified 24 molting proteins that affected ecdysis after knockdown, with different physiological functions, including old cuticle protein recycling, molting fluid pressure balance, detoxification, and signal detection and transfer of molting fluids. We report that insects secrete molting fluid for protection and regulation of ecdysis, which indicates a way to develop new pesticides through interrupting insect ecdysis in the future.     

棉铃虫蜕皮时期同工酶表达模式

同工酶广泛存在于不同种属生物的组织细胞中,在生物发育的不同阶段有着特定的表达模式和重要的生理功能。昆虫蜕皮是在促前胸腺激素（PTTH）、蜕皮激素和保幼激素共同控制下由一系列基因表达和调控的级联反应。阐明蜕皮发育过程中同工酶的表达模式,可以为研究蜕皮的分子机理提供新的分子靶标,为研制生长调节剂类杀虫剂提供检测的分子标记。该研究分析了棉铃虫Helicoverpa armigera蜕皮时期不同组织中过氧化物酶、乙醇脱氢酶和酯酶的表达模式,找到了3种蜕皮差异表达的过氧化物酶, 2种蜕皮或变态差异表达的乙醇脱氢酶,3种蜕皮差异表达的酯酶。生长调节剂类化学杀虫剂非甾醇类蜕皮激素竞争物RH24-85可以诱导3种酯酶表达上调,可能与蜕皮有关。这些结果为进一步研究棉铃虫蜕皮的分子机理和检测促蜕皮生长调节剂类化学杀虫剂提供了新的分子靶标。