A Glutathione Peroxidase Gene from Litopenaeus vannamei Is Involved in Oxidative Stress Responses and Pathogen Infection Resistance

Optimization of Selenium Inclusion Level in the Larval Diet of Labeo rohita

The nutritional requirement of fish larvae remains a limiting factor in advanced aquaculture. Micronutrients are crucial for early development, but their dietary inclusion level in the larval feed of carps has not been standardized. The present study was executed to determine the optimum dietary inclusion level of organic and inorganic selenium in the larval feed of Rohu, Labeo rohita. A 35-day feeding trial in triplicate under semi-control conditions was conducted in 21 troughs divided into seven groups. Each trough (capacity 4.0 L) contained 200 larvae (average body weight 0.4 mg). The first group (control) was reared on nano-particulate basal diet (CP 50%), while three groups Se-Na(0.5), Se-Na(1), and Se-Na(1.5) were fed basal diet supplemented with graded levels (0.5-1.5 mg/kg diet) of inorganic form of Se, sodium selenite (Se-Na). The last three groups (Se-Met(0.5), Se-Met(1), and Se-Met(1.5)) were fed organic form of dietary Se, selenium methionine (Se-Met) at the same inclusion level as Se-Na. Results indicated the curvilinear relationship of dietary Se levels with body weight, activity of digestive enzymes (protease, amylase, lipases, and trypsin), and antioxidant enzymes (SOD, CAT, POD, and GSH-Px) activity, intestinal villi, width, and absorptive area. A positive correlation was observed with up to 0.5 and 1 mg/kg diet of Se-Na and Se-Met, respectively; however, above these levels, a negative impact was observed. The upregulation of growth hormone mediator (IGF-1) and downregulation of heat shock protein (HSP-70) also followed a similar trend in response to Se-Na and Se-Met inclusion. Based on the results, 1 mg/kg diet Se-Met could be considered the optimum level and is recommended for the early rearing of rohu larvae.

Research and Application of Chitosan Nanoparticles in Orthopedic Infections

Orthopedic infection is one of the most intractable orthopedic problems. Bacteria resistant to antibiotics also develop gradually. Chitosan is widely used in the Biomedical field because of its high biocompatibility, biodegradability, and antibacterial activity. Chitosan-based drug delivery systems are frequently utilized to produce controlled medication release. When combined with antibiotics, synergistic antibacterial effects can be achieved. Chitosan-based nanoparticles are one of the most widely used applications in drug delivery systems. The focus of this review is to provide information on new methods being developed for chitosan-based nanoparticles in the field of bone infection treatment, including chitosan nanoparticles for antibacterial purposes, Ch-loaded with antibiotics, Ch-loaded with metal, and used as immune adjuvants. It may Provide ideas for the fundamental research and the prospects of future clinical applications of orthopedic infections.

Toxic effects of microplastics and nitrite exposure on intestinal histology, digestion, immunity, and microbial community of shrimp Litopenaeus vannamei

Nitrite and microplastics (MPs) are environmental pollutants that threaten intestinal integrity and affect immune function of shrimp. In this study, the shrimp Litopenaeus vannamei were exposed to the individual and combined stress of nitrite and microplastics for 14 days, and the changes of intestinal histology and physiological functions were investigated. After single and combined stress, affectations occurred in intestinal tissue; the antioxidant enzyme activities (MDA, H2O2, CAT increased) and gene expression levels (CAT, SOD, GPx, HSP70 up-regulated) changed. The expression levels of detoxification genes (CYP450, UGT down-regulated, GST up-regulated), apoptosis genes (CASP-3 up-regulated) and endoplasmic reticulum stress genes (Bip, GRP94 down-regulated) changed. Furthermore, the stress also increased intestinal microbial diversity, causing bacterial composition variation, especially beneficial bacteria and pathogenic bacteria. These results suggested that nitrite and microplastics stress had adverse effects on the intestinal health of L. vannamei by affecting intestinal tissue morphology, immune response and microbial community.

Methylglyoxal metabolism is altered during defence response in pigeonpea (Cajanus cajan (L.) Millsp.) against the spotted pod borer (Maruca vitrata)

Pigeonpea (Cajanus cajan ) production can be affected by the spotted pod borer (Maruca vitrata ). Here, we identified biochemical changes in plant parts of pigeonpea after M. vitrata infestation. Two pigeonpea genotypes (AL 1747, moderately resistant; and MN 1, susceptible) were compared for glyoxalase and non-glyoxalase enzyme systems responsible for methylglyoxal (MG) detoxification, γ-glutamylcysteine synthetase (γ-GCS), glutathione-S-transferase (GST) and glutathione content in leaves, flowers and pods under control and insect-infested conditions. MN 1 had major damage due to M. vitrata infestation compared to AL 1747. Lower accumulation of MG in AL 1747 was due to higher activities of enzymes of GSH-dependent (glyoxylase I, glyoxylase II), GSH-independent (glyoxalase III) pathway, and enzyme of non-glyoxalase pathway (methylglyoxal reductase, MGR), which convert MG to lactate. Decreased glyoxylase enzymes and MGR activities in MN 1 resulted in higher accumulation of MG. Higher lactate dehydrogenase (LDH) activity in AL 1747 indicates utilisation of MG detoxification pathway. Higher glutathione content in AL 1747 genotype might be responsible for efficient working of MG detoxification pathway under insect infestation. Higher activity of γ-GCS in AL 1747 maintains the glutathione pool, necessary for the functioning of glyoxylase pathway to carry out the detoxification of MG. Higher activities of GST and GPX in AL 1747 might be responsible for detoxification of toxic products that accumulates following insect infestation, and elevated activities of glyoxylase and non-glyoxylase enzyme systems in AL 1747 after infestation might be responsible for reducing reactive cabanoyl stress. Our investigation will help the future development of resistant cultivars.

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.

Transcriptomic variations associated with salinity stress in Penaeus indicus

BACKGROUND

The Indian white shrimp, Penaeus indicus a native species of India, is important brackishwater aquaculture species. Shrimps are euryhaline in nature and they regulate osmotic and ionic concentrations by osmoregulatory process. However, variations in abiotic factors such as salinity result in stress to the shrimps during culture period affecting their growth and immunity.

METHODS AND RESULTS

To understand the adaptive mechanism to stress in low salinity conditions, RNA-seq was used to compare the transcriptomic response of P. indicus upto 3 weeks. De novo assembly using Trinity assembler generated a total of 173,582 transcripts. The assembly had a mean length of 854 bp, N50 value of 1243 bp and GC content of 42.33%. Differential gene expression analysis, resulted in identification of 2130, 3090, and 5351 DEGs in 7 days, 14 days and 21 days respectively of salinity stress period. The pathway prediction of the assembled trinity transcripts using KEGG database showed total number of 329 pathways linking 12,430 transcripts. KEGG pathway enrichment analyses led to the identification of several enriched pathways related to lipid metabolism, amino acid metabolism, glycolysis, signalling pathways etc. Selected genes involved in osmoregulatory process and immune response in shrimps were validated and analysed for the gene expression levels by quantitative real-time PCR (qPCR).

CONCLUSION

This study on the adaptive transcriptomic response of P. indicus to low salinity, will further help in our understanding of the molecular mechanisms underlying osmoregulation mechanism in shrimps.

Antiviral Activity of Biosynthesized Silver Nanoparticles from Pomegranate (Punica granatum L.) Peel Extract against Tobacco Mosaic Virus

Tobacco mosaic virus (TMV) is a major pathogen affecting tomato plants worldwide. The efficacy of silver nanoparticles (Ag-NPs) mediated by Punica granatum biowaste peel extract in mitigating the negative impact of TMV infection on tomato growth and oxidative stress was investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Visible (UV-Vis) spectrophotometer, X-ray Diffraction (XRD), dynamic light scattering (DLS), zeta potential, energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectra (FTIR). Results of SEM analysis of green Ag-NPs revealed the presence of condensed spherical or round NPs with diameters ranging between 61 and 97 nm. TEM confirmed the SEM results and showed round-shaped Ag-NPs with an average size of 33.37 ± 12.7 nm. The elemental analysis (EDX) of prepared Ag-NPs revealed the presence of elemental Ag as a major peak (64.43%) at 3-3.5 KeV. The FTIR revealed several functional groups on the prepared Ag-NPs, for which three treatment strategies for Ag-NP applications were evaluated in the greenhouse study and compared to inoculated TMV and control plants: pre-infection treatment (TB), post-infection treatment (TA), and dual treatment (TD). The results showed that the TD strategy is the most effective in improving tomato growth and reducing viral replication, whereas all Ag-NP treatments (TB, TA, and TD) were found to significantly increase expression of the pathogenesis-related (PR) genes PR-1 and PR-2, as well as polyphenolic compounds, HQT, and C4H genes compared to control plants. In contrast, the flavonoid content of tomato plants was not affected by the viral infection, while the phenolic content was significantly reduced in the TMV group. Furthermore, TMV infection led to a significant increase in oxidative stress markers MDA and H₂O₂, as well as a reduction in the enzymatic activity of the antioxidants PPO, SOD, and POX. Our results clearly showed that the application of Ag-NPs on TMV-infected plants reduces virus accumulation, delays viral replication in all treatments, and greatly enhances the expression of the CHS gene involved in flavonoid biosynthesis. Overall, these findings suggest that treatment with Ag-NPs may be an effective strategy to mitigate the negative impact of TMV infection on tomato plants.

Ocimum basilicum-Mediated Synthesis of Silver Nanoparticles Induces Innate Immune Responses against Cucumber Mosaic Virus in Squash

Cucumber mosaic virus (CMV) causes a significant threat to crop output sustainability and human nutrition worldwide, since it is one of the most prevalent plant viruses infecting most kinds of plants. Nowadays, different types of nanomaterials are applied as a control agent against different phytopathogens. However, their effects against viral infections are still limited. In the current study, the antiviral activities of the biosynthesized silver nanoparticles (Ag-NPs) mediated by aqueous extract of Ocimum basilicum against cucumber mosaic virus in squash (Cucurbita pepo L.) were investigated. The prepared Ag-NPs were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and zeta potential distribution techniques. DLS, SEM, and TEM analyses showed that the Ag-NPs were spherical, with sizes ranging from 26.3 to 83 nm with an average particle size of about 32.6 nm. FTIR identified different functional groups responsible for the capping and stability of Ag-NPs. The zeta potential was reported as being -11.1 mV. Under greenhouse conditions, foliar sprays of Ag-NPs (100 µg/mL) promoted growth, delayed disease symptom development, and significantly reduced CMV accumulation levels of treated plants compared to non-treated plants. Treatment with Ag-NPs 24 h before or after CMV infection reduced CMV accumulation levels by 92% and 86%, respectively. There was also a significant increase in total soluble carbohydrates, free radical scavenging activity, antioxidant enzymes (PPO, SOD, and POX), as well as total phenolic and flavonoid content. Furthermore, systemic resistance was induced by significantly increasing the expression levels of pathogenesis-related genes (PR-1 and PR-5) and polyphenolic pathway genes (HCT and CHI). These findings suggest that Ag-NPs produced by O. basilicum could be used as an elicitor agent and as a control agent in the induction and management of plant viral infections.

Protective and Curative Activities of Paenibacillus polymyxa against Zucchini yellow mosaic virus Infestation in Squash Plants

The use of microbial products as natural biocontrol agents to increase a plant's systemic resistance to viral infections is a promising way to make agriculture more sustainable and less harmful to the environment. The rhizobacterium Paenibacillus polymyxa has been shown to have strong biocontrol action against plant diseases, but its antiviral activity has been little investigated. Here, the efficiency of the culture filtrate of the P. polymyxa strain SZYM (Acc# ON149452) to protect squash (Cucurbita pepo L.) plants against a Zucchini yellow mosaic virus (ZYMV, Acc# ON159933) infection was evaluated. Under greenhouse conditions, the foliar application of the culture filtrate of SZYM either in protective or curative treatment conditions enhanced squash growth, reduced disease severity, and decreased ZYMV accumulation levels in the treated plants when compared to the non-treated plants. The protective treatment group exhibited the highest inhibitory effect (80%), with significant increases in their total soluble carbohydrates, total soluble protein content, ascorbic acid content, and free radical scavenging activity. Furthermore, a considerable increase in the activities of reactive oxygen species scavenging enzymes (superoxide dismutase, polyphenol oxidase, and peroxidase) were also found. In addition, the induction of systemic resistance with a significant elevation in the transcriptional levels of polyphenolic pathway genes (CHS, PAL, and C3H) and pathogenesis-related genes (PR-1 and PR-3) was observed. Out of the 14 detected compounds in the GC-MS analysis, propanoic acid, benzenedicarboxylic acid, tetradecanoic acid, and their derivatives, as well as pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) were the primary ingredient compounds in the ethyl acetate extract of the SZYM-culture filtrate. Such compounds may act as elicitor molecules that induce systemic resistance against viral infection. Consequently, P. polymyxa can be considered a powerful plant growth-promoting bacterium (PGPB) in agricultural applications as well as a source of bioactive compounds for sustainable disease management. As far as we know, this is the first time that P. polymyxa has been shown to fight viruses in plants.