Phenoloxidase Activity Research Articles

Single and combined effects of CuSO4 and polyethylene microplastics on biochemical endpoints and physiological impacts on the narrow-clawed crayfish Pontastacusleptodactylus

This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L−1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L−1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L−1 MPs and 0.5 mg L−1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs.

Dietary postbiotics supplementation improves growth, survival rate, antioxidant capacity, non-specific immunity and gut health of juvenile oriental river prawn (Macrobrachium nipponense)

Antibiotics use in aquaculture cause multiple adverse effects on aquatic animal health. Accordingly, studies on alternative approaches to antibiotics in aquaculture are urgently required. This study investigated the effects of dietary postbiotics as an alternative to florfenicol antibiotic on growth performance, survival rate, antioxidant capacity, non-specific immunity, and gut health of juvenile oriental river prawn (Macrobrachium nipponense). Seven isonitrogenous and isocaloric experimental diets were formulated containing 0% (control), 0.25%, 0.5%, 1%, 2% and 4% postbiotics. These experimental diets were fed to three replicates of 70 juvenile prawns (initial weight 0.110 ± 0.010 g) for eight weeks. In addition, a diet containing 0.2% florfenicol (FFC0.2) was included as the antibiotic treatment, which was fed to the prawns for two weeks. Results showed that feeding the prawns on the postbiotics diets improved weight gain and survival rate. The prawns fed on the antibiotics or postbiotics diets increased antioxidant capacity in the hepatopancreas. Moreover, the prawns fed on the postbiotics diets increased significantly non-specific immunity. The optimum amount of postbiotics required for maximum non-specific immunity was 0.76%, 0.86% and 2.85% based on acid phosphatase, alkaline phosphatase and phenoloxidase activities, respectively. The prawns fed on the postbiotics diets upregulated significantly the mRNA expression of immunity related genes, which were downregulated significantly in the prawns fed on the FFC0.2 diet. Furthemore, the prawns fed on the 1% and 2% postbiotics diets had longer microvilli with closely packed intestinal epithelial cell and basement membrane. In summary, supplementing 0.76 to 2.66% postbiotics in the diets for M. nipponense improves growth performance, survival rate, antioxidant capacity, non-specific immunity and gut health compared with florfenicol antibiotic.

Role of prophenoloxidase 1 from the beetle Octodonta nipae in melanized encapsulation of a wasp egg

Exploring the function of the host immune system can help to understand the host-parasitoid interaction. Prophenoloxidase (PPO) is crucial in defensive melanization during the encapsulation of wasp eggs. However, the existence of multiple PPO sequences increases the difficulty of exploring the specific functions of individual PPOs. We previously identified three PPOs in the nipa palm hispid beetle, Octodonta nipae. Our current work showed that OnPPO1 and OnPPO2 possessed the typical characteristics of the type III copper family, but OnPPO3 lacked the conserved histidine residues, and its active sites were substituted with Gln. OnPPOs showed the highest expression in hemocytes, but OnPPO3 presented extremely low abundance compared with that of OnPPO1 and OnPPO2, and only OnPPO1 showed a quick response after wasp infection. OnPPO1 knockdown decreased the encapsulation index and inhibited melanization, whereas silencing of OnPPO3 appeared to have no adverse effect on encapsulation and melanization, and silencing of OnPPO2 presented low RNAi efficiency. Moreover, the cleavage of recombinant OnPPO1 produced a 62 kDa fragment with high PO activity. OnPPO1 could be produced by oenocytoids, granulocytes and plasmatocytes, and was distributed around wasp eggs during capsule formation. Overall, our results indicate that proteolytic cleavage of OnPPO1 plays key roles in the melanized encapsulation of wasp eggs. This finding illuminates the mechanism of PPO activation in this invasive beetle and provides guidance for its biological control.

Characterization of the defense properties of healthy and diseased coral mucus

The surface mucus layer of corals aids in feeding, silt removal, and defense against pathogens. However, first line of defense of secreted mucus of corals against tissue damage generated through pathogen or environmental factors is poorly understood. Hence, we used various methods such as a well diffusion assay and tests for quorum quenching, free radical scavenging, antioxidant enzyme expression and phenoloxidase (PO) activity to determine the mucus defense properties using mucus of healthy and diseased Porites sp. and Acropora sp. Interestingly the coral mucus showed antimicrobial activity against coral pathogens such as bacteria and protozoan ciliates. Inhibition of the N-Acyl homoserine lactone (AHL) molecule suggests quorum quenching. Free radical scavenging of mucus was screened using hydrogen peroxide, hydroxyl radical, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) methods, which was found significantly more in diseased corals (p < 0.05). Antioxidant enzymes superoxide dismutase (SOD), catalase, and peroxidase activity were observed in both the diseased and healthy coral mucus. The presence of serine and metalloproteases was also detected in coral mucus. Further, phenoloxidase (PO) activity was highest in diseased coral mucus affected by pink line syndrome and white patch Acropora sp. disease than the healthy coral mucus. Thus, the present study of antimicrobial properties, antioxidant enzymes, and quorum quenching properties in coral mucus may aid in understanding the corals defense and survival against pathogens and any abiotic stress.

Assessment of Bacillus subtilis fermented Caulerpa microphysa byproduct as feed additive on the growth performance, immune regulation and disease resistance of white shrimp (Litopenaeus vannamei)

In this study, the immunomodulatory and antioxidant activity of fermented Caulerpa microphysa byproduct (FCMB) by Bacillus subtilis was evaluated, and its potential as a feed additive for white shrimp (Litopenaeus vannamei) was explored. In vitro experiments showed that the FCMB supernatant contained polysaccharides, polyphenols and flavonoids, and exhibited antioxidant properties as assessed by various antioxidant assays. Additionally, the FCMB supernatant was found to increase the production rate of reactive oxygen species and the activity of phenoloxidase in hemocytes in vitro. Furthermore, the results of the in vivo feeding trial showed that dietary 5 g kg−1 FCMB significantly improved the weight gain and specific growth rate of white shrimp after 56 days of feeding. Although there were no significant differences in total hemocyte count, phagocytosis, superoxide anion production rate, and phenoloxidase activity among the experimental groups, upregulation of immune-related genes was observed, particularly in the hepatopancreas and hemocytes of shrimps fed with 5 g or 50 g FCMB per kg feed, respectively. In the pathogen challenge assay, white shrimp fed with 5 % FCMB exhibited a higher survival rate compared to the control group following Vibrio parahaemolyticus challenge. Therefore, it is concluded that the fermented byproduct of C. microphysa, FCMB, holds potential as a feed additive for enhancing the growth performance and disease resistance against V. parahaemolyticus in white shrimp.

The immune response of Locusta migratoria manilensis at different times of infection with Paranosema locustae.

Paranosema locustae is an entomopathogenic microsporidia with promising potential for controlling agricultural pests, including Locusta migratoria manilensis. However, it has the disadvantage of having a slow insecticidal rate, and how P. locustae infection impacts the host immune response is currently unknown. The present study investigated the effect of P. locustae on the natural immune response of L. migratoria and the activities of enzymes that protect against oxidative stress. Infection with P. locustae increased the hemocytes and nodulation number of L. migratoria at the initial stage of infection. The hemocyte-mediated modulation of immune response was also affected by a decrease in the number of hemocytes 12 days postinfection. Superoxide dismutase activity in locusts increased in the early stages of infection but decreased in the later stages, whereas the activities of peroxidase (POD) and catalase (CAT) showed opposite trends may be due to their different mechanisms of action. Furthermore, the transcription levels of mRNA of antimicrobial peptide-related genes and phenoloxidase activity in hemolymph in L. migratoria were suppressed within 15 days of P. locustae infection. Overall, our data suggest that P. locustae create a conducive environment for its own proliferation in the host by disrupting the immune defense against it. These findings provide useful information for the potential application of P. locustae as a biocontrol agent.

Effects of dietary melatonin on antioxidant and immune function of the Pacific white shrimp (Litopenaeus vannamei), as determined by transcriptomic analysis

Melatonin (MT) is regarded as an antioxidant and immunostimulant that can efficiently scavenge free radicals and activate antioxidant enzymes. The aim of this study was to investigate the effects of dietary MT on the growth performance and immune function of the Pacific white shrimp (Litopenaeus vannamei). Six groups of L. vannamei were supplemented with dietary MT at 0, 22.5, 41.2, 82.7, 165.1, and 329.2 mg/kg levels for 2 months. RNA-Seq analysis was performed to obtain transcriptome data of the control group and the group supplemented with dietary MT at 82.7 mg/kg BW. In total, 1220 DEGs (799 up-regulated and 421 down-regulated) were identified. Pathways and genes related to growth performance and immune function were verified by real-time quantitative polymerase chain reaction. The total hemocyte count, phagocytosis rate, and respiratory burst were significantly increased in the MT (82.7 mg/kg BW) group as compared to the control group. Analysis of antioxidant-related enzymes in the hepatopancreas showed that dietary MT (82.7 mg/kg BW) significantly increased activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, while dietary MT at 41.2 mg/kg BW significantly increased activities of glutathione S-transferase, lysozyme (LZM), and phenoloxidase (PO). At the transcriptional level, dietary MT up-regulated expression levels of genes associated with antioxidant immunity and growth, which included PO, SOD, LZM, GPx, chitin synthase, ecdysone receptor, calcium–calmodulin dependent protein kinase I, and retinoid X receptor. In conclusion, dietary MT may improve the growth performance and immune function of L. vannamei to some extent.

Endophytic colonization of sugar beet by Beauveria varroae and Beauveria bassiana reduces performance and host preference in army worm, Spodoptera littoralis

Spodoptera littoralis (Lepidoptera: Noctuidae) Boisduval 1833 is a voracious leaf feeder and major agricultural pest attacking numerous crops. Development of insecticide resistance hampers management efforts for S. littoralis and entomopathogenic fungi represent one possible alternative management tool. Here, we quantified colonization of sugar beet, Beta vulgaris L, with two fungal entomopathogens, Beauveria varroae Vuillemin 1912 and Beauveria bassiana (Balsamo) Vuillemin 1912 (Ascomycota: Hypocreales), and examined their endophytic effects on biological and reproductive parameters of S. littoralis. Two methods were used to inoculate sugar beet: soaking seeds in spore suspension and spray application of conidia onto leaves. For both methods, fungal suspensions with concentrations of 1 × 104 and 1 × 108 conidia/ml colonized roots, stems, and leaves of sugar beet. The colonization rate increased over time. Following inoculation of seeds, weight gain of S. littoralis larvae fed on leaves infected with endophytic fungi was reduced compared with controls. Furthermore, protease and lipase activities in the gut of S. littoralis decreased with increasing concentration of fungus applied to plants. An increase in phenol oxidase activity in the gut also indicated increased defense response of larvae feeding on Beauveria-infected leaves. Both B. bassiana and B. varroae decreased the duration of larval and pupal stages, adult emergence, and oviposition by females. Incubation of sugar beet seeds with B. varroae or B. bassiana decreased survival of pupae and egg laying by female moths on endophyte-infested treatments by 30 and 50%, respectively, compared with controls. Furthermore, an initially female biased sex ratio decreased toward 50:50 over time in populations of S. littoralis reared on sugar beet colonized by fungal endophytes as compared with controls, which remained female-biased. Endophyte inoculation increased growth of sugar beet compared with controls. Our results indicate that B. bassiana and B. varroae affect survival of S. littoralis and may be useful for management of this pest.

Immunosuppressive effect of Plantago major on the innate immunity of Galleria mellonella.

Greater plantain (Plantago major), a medicinal plant species, is used in folk medicine for the treatment of various diseases in many countries of the world. Different studies have shown that the bioactive components contained in the plant have a dual effect. It was also reported that in vivo and in vitro studies showed different results. The aim of the study was to determine the effects of P. major extract on the hemocyte-mediated and humoral immune responses of the invertebrate model organism Galleria mellonella, which is widely used in immune studies. In the evaluation of these effects, total hemocyte count, encapsulation, melanization, phenoloxidase, superoxide dismutase, catalase, malondialdehyde and total protein parameters were evaluated. The results of the study showed that the total hemocyte count did not change, that the encapsulation responses decreased, that the melanization responses and phenoloxidase activity increased and that the superoxide dismutase activity decreased. As a result, it was determined that high doses of P. major had negative effects on cell-mediated immunity and antioxidant defence and positive effects on melanization. High doses and continuous use of P. major may have negative effects on living things.

Toxic effect of Cd burden on the gut microflora and immune responses of wolf spider Pardosa pseudoannulata

Spiders are dominant predators in the paddy ecosystem, but the immunotoxicity induced by environmental contaminants like heavy metals is still largely unknown. The gut microbiota-host interaction was the basic immune mechanism discovered in the arthropods. Here, we investigated the gut microflora and immune responses of wolf spider Pardosa pseudoannulata under Cd burden. Cd exposure was identified to shape the gut microbial community structure of spiders, with increased levels of Firmicutes and pathogens, and decreased levels of Proteobacteria and Bacteroidota. The alteration of microbiota-derived immune messengers like peptidoglycan (PGN) was also observed. ELISA and hemolymph metabolomic analysis showed that the activities of immune effectors phenoloxidase (PO) and lysozyme (LZM) and the abundance of tyrosine derivates were decreased, which indicated the suppression of Cd on the melanization immune response of spiders. Correlation analysis revealed a close relationship between the impaired immune system and the disordered microbiota. This study provides insight into the underlying mechanisms of the gut microflora-immune system interaction of P. pseudoannulata in response to Cd burden.

Spätzle processing enzyme is required to activate dorsal switch protein 1 induced Toll immune signalling pathway in Tenebrio molitor.

Dorsal switch protein 1 (DSP1) acts as a damage-associated molecular pattern (DAMP) molecule to activate immune responses in Tenebrio molitor. From a previous study in Spodoptera exigua, we found that DSP1 activates Toll immune signalling pathway to induce immune responses by melanisation, PLA2 activity and AMP synthesis. However, the target site of DSP1 in this pathway remains unknown. The objective of this study was to determine the role of spätzle processing enzyme in the DSP1 induced toll immune signalling pathway. To address this, we analyzed spätzle processing enzyme (Tm-SPE) of the three-step serine protease cascade of T. molitor Toll pathway. Tm-SPE expressed in all developmental stages and larval tissues. Upon immune challenge, its expression levels were upregulated but significantly reduced after RNA interference (RNAi). In addition, the induction of immune responses upon immune challenge or recombinant DSP1 injection was significantly increased. Loss of function using RNA interference revealed that the Tm-SPE is involved in connecting DSP1 induced immune responses like hemocyte nodule formation, phenoloxidase (PO) activity, phospholipase A2 (PLA2) activity and antimicrobial peptide (AMP) synthesis. These suggest that Tm-SPE controls the DSP1 induced activation of Toll immune signalling pathway required for both cellular and humoral immune responses. However, to confirm the target molecule of DSP1 in three-step proteolytic cascade, we have to check other upstream serine proteases like Spatzle activating enzyme (SAE) or modular serine protease (MSP).

The effect of reactive oxygen species (ROS) in immunity and WSSV infection of Scylla paramamosain

Reactive oxygen species (ROS) are typically regarded as being generated by the cellular respiratory chain or by cells under pathological damage, which play a crucial role as signaling molecules in promoting hemocytes circulation and normal cellular physiological functions. In this study, the antioxidant N-acetylcysteine (NAC) was used to reduce ROS in vivo and in vitro, which to analyze the effect of ROS on innate immunity and viral infection of mud crab. The total hemocyte count (THC), phenoloxidase (PO), superoxide dismutase (SOD) activity, immune-relative genes were analyzed, respectively. Moreover, the effect of ROS on WSSV infection was analyzed by THC and hemocytes apoptosis. The data showed that NAC could effectively remove and inhibit intracellular ROS. The THC of NAC group was reduced at 12 h and 24 h compared with that of control. And the inhibition of ROS by NAC could increase the SOD activity with control group, while increased the PO activity caused by early WSSV infection. And NAC could up-regulate the expression of MCM7, JAK, TLR and proPO significantly, while down-regulate the expression of Astakine, proPO, caspase and p53. Similarly, NAC could inhibit WSSV-induced apoptosis of S. paramamosain hemocytes. The data illustrated that ROS participates in the interaction between hemocytes and virus infection by regulating innate immunity. Especially, after NAC inhibited ROS, the expression of hemocytes proliferation gene Astakine was also inhibited, which may indicate that ROS is related to the process of hemocytes proliferation. The data will show a preliminary exploration on the regulatory role of ROS in crustacean immune system.

Enterobacter Strain IPPBiotE33 Displays a Synergistic Effect with Bacillus thuringiensis Bt185.

The discovery and isolation of new non-Bt insecticidal bacteria and genes are significant for the development of new biopesticides against coleopteran pests. In this study, we evaluated the insecticidal activity of non-Bt insecticidal bacteria, PPBiotE33, IPPBiotC41, IPPBiotA42 and IPPBiotC43, isolated from the peanut rhizosphere. All these strains showed insecticidal activity against first- and third-instar larvae of Holotrichia parallela, Holotrichia oblita, Anomala corpulenta and Potosia brevitarsis. IPPBiotE33 showed the highest toxicity among the four strains and exhibited virulence against Colaphellus bowringi. The genome of IPPBiotE33 was sequenced, and a new protein, 03673, with growth inhibition effects on C. bowringi was obtained. In addition, IPPBiotE33 had a synergistic effect with Bacillus thuringiensis Bt185 against H. parallela in bioassays and back-inoculation experiments with peanut seedlings. IPPBiotE33 induced a decrease in hemocytes and an increase in phenol oxidase activity in H. parallela hemolymph, known as the immunosuppressive effect, which mediated synergistic activity with Bt185. This study increased our knowledge of the new insecticidal strain IPPBiotE33 and shed new light on the research on new insecticidal coaction mechanisms and new blended pesticides.

Levamisole Influences the Immune Response of Freshwater Prawn, &lt;i&gt;Macrobrachium rosenbergii&lt;/i&gt; and its Resistance to Nitrite Stress and &lt;i&gt;Aeromonas hydrophila&lt;/i&gt; Infection

The present study evaluated the effectiveness of dietary levamisole in the modulation of innate immunity and reducing the percent mortality against nitrite stress or Aeromonas hydrophila infection in giant freshwater prawn, Macrobrachium rosenbergii. Haemolymph agglutinin and total protein levels, lysozyme activity, phenoloxidase (PO) activity, total and differential haemocyte counts, induced nitrite stress and mortality (%) against Aeromonas hydrophila challenge were measured in sub-adult M. rosenbergii fed with diets containing levamisole at 0, 125, 250 and 500 mg/kg feed for 7 or 14 days. M. rosenbergii fed with a diet containing 250 mg levamisole/kg feed for 14 days showed significant (P&lt;0.05) increase in haemagglutination titre, PO activity, undifferentiated haemocyte count, resistance to nitrite stress and survival against A. hydrophila challenge. On the contrary, graded levels of levamisole feeding for 7 days failed to modulate most of the immune parameters or reduce the percent mortality against A. hydrophila challenge or nitrite stress. It is therefore concluded that administration of levamisole in the diet at 250 mg/kg feed for 14 days in sub-adult M. rosenbergii could enhance the immune ability and increase its resistance to A. hydrophila infection and nitrite stress.

Two clip-domain serine protease homologs, cSPH35 and cSPH242, act as a cofactor for prophenoloxidase-1 activation in Drosophila melanogaster.

Insect phenoloxidases (POs) catalyze phenol oxygenation and o-diphenol oxidation to form reactive intermediates that kill invading pathogens and form melanin polymers. To reduce their toxicity to host cells, POs are produced as prophenoloxidases (PPOs) and activated by a serine protease cascade as required. In most insects studied so far, PPO activating proteases (PAPs) generate active POs in the presence of a high Mr cofactor, comprising two serine protease homologs (SPHs) each with a Gly residue replacing the catalytic Ser of an S1A serine protease (SP). These SPHs have a regulatory clip domain at the N-terminus, like most of the SP cascade members including PAPs. In Drosophila, PPO activation and PO-catalyzed melanization have been examined in genetic analyses but it is unclear if a cofactor is required for PPO activation. In this study, we produced the recombinant cSPH35 and cSPH242 precursors, activated them with Manduca sexta PAP3, and confirmed their predicted role as a cofactor for Drosophila PPO1 activation by MP2 (i.e., Sp7). The cleavage sites and mechanisms for complex formation and cofactor function are highly similar to those reported in M. sexta. In the presence of high Mr complexes of the cSPHs, PO at a high specific activity of 260 U/μg was generated in vitro. To complement the in vitro analysis, we measured hemolymph PO activity levels in wild-type flies, cSPH35, and cSPH242 RNAi lines. Compared with the wild-type flies, only 4.4% and 18% of the control PO level (26 U/μl) was detected in the cSPH35 and cSPH242 knockdowns, respectively. Consistently, percentages of adults with a melanin spot at the site of septic pricking were 82% in wild-type, 30% in cSPH35 RNAi, and 53% in cSPH242 RNAi lines; the survival rate of the control (45%) was significantly higher than those (30% and 15%) of the two RNAi lines. These data suggest that Drosophila cSPH35 and cSPH242 are components of a cofactor for MP2-mediated PPO1 activation, which are indispensable for early melanization in adults.

Tyramine mediates growth performance, immune response, and physiological regulation of Litopenaeus vannamei through dietary administration

In this study, the effects of feeding diets containing tyramine (TA) to Litopenaeus vannamei at levels of 10 (TA10), 50 (TA50), and 100 (TA100) mg/kg on growth performance, immune parameters, hemolymph glucose and lactate level, biogenic amine synthesis, and resistance against Vibrio alginolyticus were investigated. Results showed that shrimp fed with TA-containing diets had significantly higher feed efficiency and percent weight gain for a period of 56 days. The total hemocyte count increased in TA10, TA50 and TA100 after 7 and 28 days, and increased in TA100 after 14 days. The phenoloxidase activity increased in TA100 after 7 days, and respiratory bursts increased in TA100 after 7 and 14 days. In terms of resistance against V. aliginolyticus infection, the phagocytic activity increased in TA10, TA50 and TA100 after 7–28 days. The clearance efficiency increased in TA10, TA50 and TA100 after 7 and 14 days, and increased in TA 100 after 28 days. Shrimp fed with TA50 and TA100 for 28 days then challenged with V. aliginolyticus had a higher survival rate compared to those fed the basal diet at 48 h–168 h post challenges. The hemolymph glucose level was significantly decreased after being fed with TA10 at 28 days and TA100 for 56 days, while the octopamine synthesis in shrimp was improved after 14 days of being fed with TA50 and TA100, and after 28 days of being fed with TA100. These findings suggest that administering a TA diet regulated the growth performance, immune response and V. aliginolyticus resistance in L. vannamei.

A Comparison of Three Protein Sources Used in Medium-Sized Litopenaeus vannamei: Effects on Growth, Immunity, Intestinal Digestive Enzyme Activity, and Microbiota Structure

The type of protein source in diets has many effects on shrimp. In this study, Litopenaeus vannamei with an initial body weight of 3.68 ± 0.002 g were fed for 8 weeks on three experimental diets (isoproteic: 41.00%; isolipidic: 7.61%) that were formulated using fish meal (FM), Chlorella sorokiniana (CHL), and Clostridium autoethanogenum protein (CAP) as the primary protein sources, respectively. This study examined the growth, non-specific immunity, intestinal digestion, and microbiota of L. vannamei after the feeding experiment concluded. Compared to the FM group, the findings indicate that the weight gain rate (WGR), specific growth rate (SGR), and protein efficiency ratio (PER) of L. vannamei were notably enhanced via dietary CAP. The CHL group exhibited the highest levels of catalase (CAT), phenoloxidase (PO), and superoxide dismutase (SOD) activities in the gills of L. vannamei, whereas the FM group had the lowest levels. Conversely, the malondialdehyde (MDA) content showed the opposite trend. Both dietary CHL and CAP promoted the digestive enzyme activities of L. vannamei, with dietary CAP having a more pronounced promotional effect. An analysis of alpha diversity indicated that the consumption of dietary CHL substantially enhanced the abundance and diversity of microbiota in the intestinal tract of L. vannamei. Furthermore, the dietary CHL significantly increased the colonization of immune-associated beneficial bacteria and inhibited the colonization of pathogenic bacteria in the intestinal tract of L. vannamei, whereas dietary CAP mainly increased the colonization of growth-associated beneficial bacteria. Functional predictions showed that different dietary protein sources affect various metabolic activities and signaling pathways of L. vannamei, and some functions, including signal transduction, cell motility, and the immune system, were significantly enhanced in the CHL group. In summary, both dietary CHL and dietary CAP promoted growth and immunity in L. vannamei compared to dietary FM. The results of this study could be helpful for the sustainable development of shrimp farming.

Ambient copper modulates immunocompetence and induces physiological responses in Penaeus monodon against white spot syndrome virus infection.

Among trace metals, copper is essential for crustaceans' normal growth and metabolism. In the present study, an attempt was made to determine whether the addition of copper in rearing water influences the physiological and immunological responses of Penaeus monodon to white spot syndrome virus infection (WSSV). Adult P. monodon were distributed in experimental tanks and exposed to 0, 0.05, 0.1, 0.2 and 0.3mgl-1 copper concentrations. After 14 days, the shrimps were challenged with WSSV and the biochemical/immune variables were determined on post-metal exposure day 14 and post-challenge days 2 and 5. Significant variations could be observed in the haemolymph (biochemical and immune) variables of P. monodon on exposure to copper and WSSV challenge. Shrimps exposed to copper at 0.1mgl-1 showed higher total haemocyte count, phenol oxidase activity, nitro blue tetrazolium salt reduction, alkaline/acid phosphatase activity, total protein, carbohydrates, lipids, glucose and cholesterol besides maximum post-challenge survival. However, exposure to copper at 0.2 and 0.3 mgl-1 increased the susceptibility to WSSV infection, showing a decrease in the biochemical/immune variables. Therefore, the present study concludes that copper in ambient water induces immunomodulation and evokes physiological responses in P. monodon at sub-lethal doses. Immunostimulatory effects elicited by copper at 0.1mgl-1 enhanced the immunocompetence and reduced the susceptibility of P. monodon to WSSV infection, conferring protection to the animals and resulting in higher survival.

Dietary administration of mangosteen, Garcinia mangostana, peel extract enhances the growth, and physiological and immunoendocrinological regulation of prawn, Macrobrachiumrosenbergii.

In this study, we investigated the potential immunostimulatory effects of mangosteen (Garcinia mangostana) peel extract on Macrobrachium rosenbergii, specifically in enhancing immunity and resistance against Lactococcus garvieae. We employed a dietary administration approach to assess the impact of different extract preparations from mangosteen peel, namely mangosteen peel powder (MPP), boiled mangosteen peel powder (MPB), and mangosteen peel extract (MPE). Following the administration of mangosteen peel extract, we evaluated growth performance, innate immune parameters, and disease resistance in the prawns. The results revealed a significant increase in total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), as well as phagocytic activity and clearance efficiency against L. garvieae. Based on these findings, we suggest that mangosteen peel extract can be utilized as an immunostimulant for prawns through dietary administration, regulating immune responses and enhancing resistance against pathogens by modulating carbohydrate metabolism.

How temperature and aridity drive lignin decomposition along a latitudinal transect in western Siberia

AbstractClimate change drives a northward shift of biomes in high‐latitude regions. This might have consequences on the decomposition of plant litter entering the soil, including its lignin component, which is one of the most abundant components of vascular plants. In order to elucidate the combined effect of climate and soil characteristics on the decomposition pattern of lignin, we investigated lignin contents and its degree of oxidative decomposition within soil profiles along a climosequence in western Siberia. Soil samples were collected from organic topsoil to mineral subsoil at six sites along a 1500‐km latitudinal transect, stretching from tundra, through taiga and forest steppe to typical steppe. The stage of lignin degradation, as mirrored by decreasing organic carbon‐normalized lignin contents and increasing oxidative alteration of the remnant lignin (acid‐to‐aldehyde ratios of vanillyl‐ and syringyl‐units [(Ac/Al)V and (Ac/Al)S]) within soil horizons, increased from tundra to forest steppe and then decreased to the steppe. Principal component analysis, involving also climatic conditions such as mean annual temperature and aridity index, showed that the different states of lignin degradation between horizons related well to the activity of phenoloxidases and peroxidases, enzymes involved in lignin depolymerization that are produced primarily by fungi and less importantly by bacteria. The low microbial lignin decomposition in the tundra was likely due to low temperature and high soil moisture, which do not favour the fungi. Increasing temperature and decreasing soil moisture, facilitating a higher abundance of fungi, led to increased fungal lignin decomposition towards the forest‐steppe biome, while drought and high pH might be responsible for the reduced lignin decomposition in the steppe. We infer that a shift of biomes to the north, driven by climate change, might promote lignin decomposition in the northern parts, whereas in the south a further retardation might be likely.