Phenoloxidase Expression Research Articles

Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle

With rising global temperatures, permafrost carbon stores are vulnerable to microbial degradation. The enzyme latch theory states that polyphenols should accumulate in saturated peatlands due to diminished phenol oxidase activity, inhibiting resident microbes and promoting carbon stabilization. Pairing microbiome and geochemical measurements along a permafrost thaw-induced saturation gradient in Stordalen Mire, a model Arctic peatland, we confirmed a negative relationship between phenol oxidase expression and saturation but failed to support other trends predicted by the enzyme latch. To inventory alternative polyphenol removal strategies, we built CAMPER, a gene annotation tool leveraging polyphenol enzyme knowledge gleaned across microbial ecosystems. Applying CAMPER to genome-resolved metatranscriptomes, we identified genes for diverse polyphenol-active enzymes expressed by various microbial lineages under a range of redox conditions. This shifts the paradigm that polyphenols stabilize carbon in saturated soils and highlights the need to consider both oxic and anoxic polyphenol metabolisms to understand carbon cycling in changing ecosystems.

Host aphid immunosuppression by Aphidius ervi venom

AbstractThe host immunosuppression by parasitic wasps is an important component of the host regulation strategy. The venom injected at the oviposition is one of the key‐factors involved in this host alteration and, in some parasitoids, its immunosuppressive role is complemented by wasp's symbionts. Most studies in this research area are related to hosts belonging to Lepidoptera and Diptera, for which a strong immune response is observed, whereas little is known for hemimetabolous host species, characterized by apparently much weaker defense barriers. To fill this research gap, here we focus on the host–parasitoid system Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae) – Aphidius ervi Haliday (Hymenoptera: Braconidae). We functionally characterized a serine protease homolog (AeSPH) protein in vivo, identified in the venom of the aphid endoparasitoid A. ervi, generating AeSPH‐depleted female wasps by RNA interference and evaluating their capacity to successfully parasitize the host. Parasitism success rate was negatively affected by AeSPH knockdown and associated with an increased phenoloxidase (PO) cascade activation in aphids, scored by measuring PO enzymatic activity and the expression of phenoloxidase activating factor 2, a proPO‐activating gene upregulated in response to A. ervi parasitism. Our results indicate that AeSPH contributes to parasitism success by inhibiting the melanization response of the host, which is therefore an important component of the defense barriers involved in the parasitoid egg suppression. The ongoing studies on other virulence factors in A. ervi venom will allow to further characterize the immunosuppression strategy and its possible broader role in the host regulation through its action on aphid symbiont development.

Humoral immune response of Galleria mellonella after mono- and co-injection with Hypericum perforatum extract and Candida albicans.

Galleria mellonella is used as a model organism to study the innate immune response of insects. In this study, the humoral immune response was assessed by examining phenoloxidase activity, fungal burden, and the expression of phenoloxidase and antimicrobial peptide genes at different time point following separate and combined injections of Hypericum perforatum extract and a nonlethal dose of Candida albicans. The administration of a plant extract at low doses increased phenoloxidase activity, while higher doses had no effect. Similarly, co-injection of a low dose of the extract with the pathogen allowed half of the yeast cells to survive after 24 h. Co-injection of plant extract with the pathogen decreased the phenoloxidase activity at the end of 4 h compared to C. albicans mono-injection. The phenoloxidase gene expressions was reduced in all experimental conditions with respect to the control. When plant extracts and the pathogen were administered together, gallerimycin and hemolin gene expressions were considerably higher compared to mono-injections of plant extracts and the pathogen. The results of this study reveal that gene activation and regulatory mechanisms may change for each immune gene, and that recognition and signaling pathways may differ depending on the involved immunoregulator.

Effect of Prebiotics and Probiotics on Phenoloxidase Expression and Activity in Penaeus Shrimps: A Meta-Analysis

Effect of Prebiotics and Probiotics on Phenoloxidase Expression and Activity in Penaeus Shrimps: A Meta-Analysis

Effect of Prebiotics and Probiotics on Phenoloxidase Expression and Activity in Penaeus Shrimps: A Meta-Analysis

Effect of Prebiotics and Probiotics on Phenoloxidase Expression and Activity in Penaeus Shrimps: A Meta-Analysis

Physiological, biochemical and HSP70 and HSP90 gene expression profiles of tropical abalone Haliotis squamata in response to Vibrio alginolyticus infection

Vibrio spp. have been known responsible for fish diseases in marine and brackish‐water systems in the tropics regions. Heat shock proteins are a highly conserved protein group that is known for its rapid response to environmental stresses, including infection. This study aimed to investigate physiological and biochemical responses of tropical abalone Haliotis squamata to Vibrio alginolyticus infection. Abalones were infected with V. alginolyticus by intramuscular injection at a dose of 105,106,107 cfu/abalone. The expression of HSP70 and HSP90 genes, the activity of superoxide dismutase, phenol oxidase and catalase enzymes, histology, falling and mortality were observed at 12, 24, 48, 72, and 96 hours post‐infection (hpi). The different expression of HSPs was found in this study. While the expression of HSP70 was downregulated after infection, the expression of HSP90 was upregulated at 12 hpi and followed by downregulated after 24 hpi for 106 cfu infection, but expressed at a normal level for 105 infection treatment. The expression ofsuperoxide dismutase and catalase increased within 12 hpi, and the expression of phenol oxidase increased after 24 hpi. V. alginolyticus is virulent with LD50 of less than 105 cfu on H. squamata with an average weight of 5.13 g, and caused enlargement of hemolymph sinus and development intraepithelial and intramuscular abscesses.

C-terminal conserved motifs of Neprilysin1 in Cotesia plutellae are not required for immune suppression of the Diamondback moth, Plutella xylostella (L.)

Abstract Cotesia plutellae, an endoparasitoid wasp, parasitizes Plutella xylostella larvae and disrupts host immune responses through parasitic factors. These immune disruptive factors are known as maternal factors (venom proteins, polydnavirus, and ovary proteins) and an embryonic factor (teratocytes). In this study, we identified neprilysin-1 (Cp-NEP1) known as a potential immunosuppressive gene from the transcriptome of venom glands in C. plutellae. Cp-NEP1 encoding 451 amino acids belonged to the hymenopteran NEP1 family through phylogenetic analysis. Based on the structural comparison, Cp-NEP1 has lacked in conserved motifs such as a substrate binding (NAYY/F), zinc-binding (HExxH and ExxxD), and protein folding and maturation (CxxW). In order to investigate the function of Cp-NEP1 in host immune response, we constructed a recombinant Cp-NEP1 (rCp-NEP1) harboring N-terminally fused 6X His-tag. rCp-NEP1 was successfully expressed in Escherichia coli and purified. Pre-heated E. coli induced the spike of nodule formation whereas co-injection of rCp-NEP1 with pre-heated E. coli exhibited suppression of nodule formation. Quantitative real-time PCR showed that expression of phenoloxidase related to nodule formation was also suppressed when rCp-NEP1 was co-injected with preheated E. coli. These results suggest that Cp-NEP1 contributes to immunosuppression and that conserved motifs lacking in Cp-NEP1 are not necessary for immune suppression in the host.

P38 MAPK is involved in the immune response to pathogenic Vibrio in the clam Meretrix petechialis

p38 mitogen-activated protein kinases (MAPKs) are involved in the response to various extracellular stimuli via regulating gene expression. In the present study, a p38 MAPK gene (MpP38) was identified from the clam Meretrix petechialis. The full-length cDNA of MpP38 measures 1,720 bp, consisting of a 134-bp 5′-UTR, a 1,095-bp ORF and a 491-bp 3′-UTR. Both the mRNA and protein expression levels of MpP38 increased after Vibrio challenge, implying that MpP38 is involved in clam immunity. Based on our previous study, a transcription factor activated by p38 MAPK, i.e. microphthalmia-associated transcription factor (MITF), participated in clam immunity by regulating the expression of phenoloxidase (PO). Coupled with other related reports, the mechanism underlying the involvement of MpP38 in clam immunity is most likely that pathogen stimuli induce the phosphorylation of p38 MAPK and thus activate MITF to regulate the expression of the immune-related gene PO. The results obtained in this study support this mechanism. First, we found that the MpP38 phosphorylation level increased in response to Vibrio challenge. Second, as revealed by a yeast two-hybrid assay, there was a direct interaction between MpP38 and MITF. Meanwhile, inhibiting the phosphorylation of MpP38 decreased the phosphorylation level of MpMITF, implying that MpP38 phosphorylation is required for MpMITF activation. Additionally, our results showed that there was a regulatory relationship between MpP38 phosphorylation level and PO expression level. With increased MpP38 phosphorylation level, the PO expression level was also increased after Vibrio challenge; when MpP38 phosphorylation was inhibited, the PO expression level was significantly decreased. This study describes the immune function of p38 MAPK in the clam for the first time and analyses its potential underlying mechanism, which will help to elucidate the immune mechanism in the clam M. petechialis.

Fat and sassy: factors underlying male mating success in a butterfly

AbstractTheory predicts that male mating success depends on resource holding potential (RHP), which is reflected by proxies of condition, such as body mass, fat content, strength, or weaponry. In species lacking any physical means to inflict injuries upon combatants, such as butterflies, the factors determining mating success are less clear. Against this background, we explored the determinants of male mating success in the tropical butterfly Bicyclus anynana Butler (Lepidoptera: Nymphalidae: Satyrinae), by comparing physiological, immunological, and morphological traits between winning and losing males. Our results showed that successful males are characterized by a better flight performance, evidenced by having longer wings, a heavier thorax, a lighter abdomen, a higher fat content, and higher phenoloxidase expression levels than their unsuccessful counterparts, when being compared after their first mating. Males that won three consecutive trials against the same combatant were also characterized by a better flight performance, having larger forewings, a higher body mass, and a higher fat content. Thus, successful males were larger and in better condition than unsuccessful ones. Strikingly, many differences found indicated an enhanced flight performance for the former, which we suggest ultimately plays the key role for male mating success in B. anynana. As fat is the main energy source for flying insects, being crucial to flight endurance and in turn presumably to male mating success, it may represent a key determinant at the proximate level.

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.

Rapid evolution of phenoloxidase expression, a component of innate immune function, in a natural population of Daphnia magna

We show rapid microevolution of one component of invertebrate innate immunity, phenoloxidase activity, in a natural population of the water flea Daphnia magna. In Daphnia hatched out of different depths of a sediment core, levels of Daphnia phenoloxidase activity showed genetic variation and increased significantly in less than a decade. We discuss this increase in Daphnia immunity over time in the light of coinciding changes in predator and parasite environment. Together with earlier-found microevolutionary responses in stress protein expression of this Daphnia population, we find simultaneous changes of different defense systems in response towards multiple enemies.

Expression of phenol oxidase and heat-shock genes during the development of Agaricus bisporus fruiting bodies, healthy and infected by Lecanicillium fungicola

The fungal pathogen Lecanicillium fungicola (formerly Verticillium fungicola) is responsible for severe losses worldwide in the mushroom (Agaricus bisporus) industry. Infected crops are characterised by masses of undifferentiated tissue (bubbles) growing in place of sporophores. The expression of three laccase genes (lcc1, lcc2 and lcc3), two tyrosinase genes (AbPPO1 and AbPPO2) and the hspA gene encoding a heat-shock protein known to be potentially associated with host-pathogen interaction was investigated in mycelial aggregates and during the development of healthy sporophores and bubbles of a susceptible cultivar. The lcc3, AbPPO2 and hspA genes were each expressed at different levels at the different stages of sporophore morphogenesis, whilst they showed a stable expression throughout bubble development. The transcript levels were similar in bubbles and at the first developmental stage of healthy fruiting bodies, both showing no tissue differentiation. These observations suggest that lcc3, AbPPO2 and hspA are associated with A. bisporus morphogenesis. Comparing the expression of the hspA gene in three susceptible and three tolerant strains showed that the latter displayed a higher level of transcript in the primordium, which is the stage receptive to the pathogen. The six strains exhibited a comparable expression in the vegetative mycelium, non-receptive to L. fungicola.

Atmospheric nitrate deposition and the microbial degradation of cellobiose and vanillin in a northern hardwood forest

Human activity has increased the amount of N entering terrestrial ecosystems from atmospheric NO 3 − deposition. High levels of inorganic N are known to suppress the expression of phenol oxidase, an important lignin-degrading enzyme produced by white-rot fungi. We hypothesized that chronic NO 3 − additions would decrease the flow of C through the heterotrophic soil food web by inhibiting phenol oxidase and the depolymerization of lignocellulose. This would likely reduce the availability of C from lignocellulose for metabolism by the microbial community. We tested this hypothesis in a mature northern hardwood forest in northern Michigan, which has received experimental atmospheric N deposition (30 kg NO 3 −–N ha −1 y −1) for nine years. In a laboratory study, we amended soils with 13C-labeled vanillin, a monophenolic product of lignin depolymerization, and 13C-labeled cellobiose, a disaccharide product of cellulose degradation. We then traced the flow of 13C through the microbial community and into soil organic carbon (SOC), dissolved organic carbon (DOC), and microbial respiration. We simultaneously measured the activity of enzymes responsible for lignin (phenol oxidase and peroxidase) and cellobiose (β-glucosidase) degradation. Nitrogen deposition reduced phenol oxidase activity by 83% and peroxidase activity by 74% when compared to control soils. In addition, soil C increased by 76%, whereas microbial biomass decreased by 68% in NO 3 − amended soils. 13C cellobiose in bacterial or fungal PLFAs was unaffected by NO 3 − deposition; however, the incorporation of 13C vanillin in fungal PLFAs extracted from NO 3 − amended soil was 82% higher than in the control treatment. The recovery of 13C vanillin and 13C cellobiose in SOC, DOC, microbial biomass, and respiration was not different between control and NO 3 − amended treatments. Chronic NO 3 − deposition has stemmed the flow of C through the heterotrophic soil food web by inhibiting the activity of ligninolytic enzymes, but it increased the assimilation of vanillin into fungal PLFAs.

Effects of age and gender on immune function of dragonflies (Odonata, Lestidae) from a wild population

Immunity is a crucial determinant of fitness. Despite this, very few studies have addressed the expression of immune function in insect populations in the wild. I present data on two immune parameters, hemocyte load and expression of phenoloxidase, in adult damselflies (Lestes viridis) from a wild population. In a comparison of newly emerged with sexually mature adults, it was found that the latter had higher hemocyte loads but lower phenoloxidase expression. Mature females showed significantly higher phenoloxidase expression than mature males. The sexual differences might be explained by gender differences in life history.

Prediction of phenol-oxidase expression in a fungus using the Fractal Dimension

The filamentous white-rot fungus Pycnoporus cinnabarinus secretes extracellular phenol-oxidases. This paper demonstrates that the Fractal Dimension of branching complexity can be used to predict the generalized yield of this oxidase in submerged culture. This confirms a positive correlation between the amount of hyphal tip branching and exo-enzyme secretion in this fungus, and under these conditions.