Selection and characterization of ssDNA aptamer targeting Macrobrachium rosenbergii nodavirus capsid protein: A potential capture agent in gold-nanoparticle-based aptasensor for viral protein detection

The giant freshwater prawn holds a significant position as a valuable crustacean species cultivated in the aquaculture industry, particularly well-known and demanded among the Southeast Asian countries. Aquaculture production of this species has been impacted by Macrobrachium rosenbergii nodavirus (MrNV) infection, which particularly affects the larvae and post-larvae stages of the prawn. The infection has been recorded to cause mortality rates of up to 100% among the affected prawns. A simple, fast, and easy to deploy on-site detection or diagnostic method is crucial for early detection of MrNV to control the disease outbreak. In the present study, novel single-stranded DNA aptamers targeting the MrNV capsid protein were identified using the systematic evolution of ligands by exponential enrichment (SELEX) approach. The aptamer was then conjugated with the citrate-capped gold nanoparticles (AuNPs), and the sensitivity of this AuNP-based aptasensor for the detection of MrNV capsid protein was evaluated. Findings revealed that the aptamer candidate, APT-MrNV-CP-1 was enriched throughout the SELEX cycle 4, 9, and 12 with the sequence percentage of 1.76%, 9.09%, and 12.42%, respectively. The conjugation of APT-MrNV-CP-1 with citrate-capped AuNPs exhibited the highest sensitivity in detecting the MrNV capsid protein, where the presence of 62.5 nM of the viral capsid protein led to a significant agglomeration of the AuNPs. This study demonstrated the practicality of an AuNP-based aptasensor for disease diagnosis, particularly for detecting MrNV infection in giant freshwater prawns.

A Comprehensive Review on the Processing of Dried Fish and the Associated Chemical and Nutritional Changes

Fish is a good source of nutrients, although it is easily spoiled. As such, drying is a common method of preserving fish to compensate for its perishability. Dried fish exists in different cultures with varying types of fish used and drying methods. These delicacies are not only consumed for their convenience and for their health benefits, as discussed in this review. Most commonly, salt and spices are added to dried fish to enhance the flavours and to decrease the water activity (aw) of the fish, which further aids the drying process. For fish to be dried effectively, the temperature, drying environment, and time need to be considered along with the butchering method used on the raw fish prior to drying. Considering the various contributing factors, several physicochemical and biochemical changes will certainly occur in the fish. In this review, the pH, water activity (aw), lipid oxidation, and colour changes in fish drying are discussed as well as the proximate composition of dried fish. With these characteristic changes in dried fish, the sensory, microbial and safety aspects of dried fish are also affected, revolving around the preferences of consumers and their health concerns, especially based on how drying is efficient in eliminating/reducing harmful microbes from the fish. Interestingly, several studies have focused on upscaling the efficiency of dried fish production to generate a safer line of dried fish products with less effort and time. An exploratory approach of the published literature was conducted to achieve the purpose of this review. This evaluation gathers important information from all available library databases from 1990 to 2022. In general, this review will benefit the fishery and food industry by enabling them to enhance the efficiency and safety of fish drying, hence minimising food waste without compromising the quality and nutritional values of dried fish.

Comparison of Different Dietary Fatty Acids Supplement on the Immune Response of Hybrid Grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) Challenged with Vibrio vulnificus

Aquaculture has been expanding in Malaysia due to the increased demand for fish products. In addition, aquaculture faces challenges in maintaining feed suitability in support of the global growth of fish production. Therefore, improvements in diet formulation are necessary to achieve the optimal requirements and attain a desirable growth efficiency and health performance in fish. Seven weeks of study were conducted to compare the equal amounts of different fatty acids (2%) (oleic acid, stearic acid, palmitic acid, and behenic acid) on the survival, the growth, and the immune response of hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) against V. vulnificus. After six weeks of the feeding trial, fish were challenged with V. vulnificus for 30 min before continuing on the same feeding regime for the next seven days (post-bacterial challenge). Fish supplemented with dietary oleic acid showed significantly (p < 0.05) enhanced immune responses, i.e., lysozyme, respiratory burst, and phagocytic activities compared to the control diet group for both pre-and post-bacterial challenges. Following the Vibrio challenge, no significant effects of supplemented fatty acid diets on survival rate were observed, although dietary oleic acid demonstrated the highest 63.3% survival rate compared to only 43.3% of the control diet group. In addition, there were no significant effects (p > 0.05) on specific growth rate (SGR), white blood cell (WBC), and red blood cell (RBC) counts among all experimental diets. The results from this study suggest that among the tested dietary fatty acids, the oleic acid diet showed promising results in the form of elevated immune responses and increased disease resistance of the hybrid grouper fingerlings challenged with V. vulnificus.

Peculiarities of innate immune memory in crustaceans

Classical characteristic of the innate immune system is the lack of ability to build up immunological memory, contrast to the adaptive immune system that is capable of "remembering" antigens, and rapidly mount a greater magnitude of immune response upon subsequent exposure to the same antigens. Peculiarly, immunological memory of innate immunity is evidenced in invertebrates. At least three different memory phenomena have been described, namely sustained unique response, recalled response, and immune shift. Studies attended to decipher the mechanistic biology of the innate immune memory reveals the role of epigenetics, which modulates the response of immune memory, and the heritability of immune memory to subsequent generations. A parthenogenetic Artemia model demonstrated successful transgenerational epigenetic inheritance of resistance trait against Vibrio campbellii. Following, the role of invertebrate hemocytes and Down syndrome cell adhesion molecule (Dscam) in innate immune memory is reviewed. While there is no vertebrate antibody homolog found in invertebrates, Dscam was found to resemble the functionality of vertebrate antibody. Insight of Dscam as immune factor was illustrated further in the current review.

Comparative genome analysis reveals a distinct influence of nucleotide composition on virus-host species-specific interaction of prawn-infecting nodavirus

Discovery of species-specific interaction between the host and virus has drawn the interest of many researchers to study the evolution of the newly emerged virus. Comparative genome analysis provides insights of the virus functional genome evolution and the underlying mechanisms of virus-host interactions. The analysis of nucleotide composition signified the evolution of nodavirus towards host specialization in a host-specific mutation manner. GC-rich genome of betanodavirus was significantly deficient in UpA and UpU dinucleotides composition, whilst the AU-rich genome of gammanodavirus was deficient in CpG dinucleotide. The capsid of MrNV and PvNV of gammanodavirus retains the highest abundance of adenine and uracil at the second codon position, respectively, which were found to be very distinctive from the other genera. ENC-GC3 plot inferred the influence of natural selection and mutational pressure in shaping the evolution of MrNV RdRp and capsid, respectively. Furthermore, CAI/eCAI analysis predicts a comparable adaptability of MrNV in squid, Sepia officinalis than its natural host, Macrobrachium rosenbergii. Thus, further study is warranted to investigate the capacity of MrNV replication in S. officinalis owing to its high codon adaptation index.

Protective effect of apple mangrove Sonneratia caseolaris extract in Edwardsiella tarda-infected African catfish, Clarias gariepinus

Outbreaks of edwardsiellosis have severe impact on the aquaculture production of African catfish Clarias gariepinus. In this study, feed supplemented with apple mangrove Sonneratia caseolaris extract was evaluated for its protective effect against Edwardsiella tarda infection in African catfish. Results showed an increase in growth performance and higher survival rate in the treatment groups in a dose dependent manner. Haematological analyses showed an increase in white blood cell count in the treatment groups. Histopathological analysis revealed degenerative changes and regeneration of liver tissue architecture in both the control and treatment groups. However, the presence of inflammatory cells was found exclusively in the kidney of T3 treatment group that was supplemented with the highest dose of extract at 3.17 mg/ml, which inferred the activation of immune response in the fish. Contrast to the deteriorative alteration observed in the kidney of the control group due to E. tarda infection, treatment group exhibited tissue regeneration and well-defined kidney tissue architecture at 3 dpi. Taken together, these results demonstrated that supplementation with the methanol extract of S. caseolaris possesses protective effect in African catfish against the infection of E. tarda.

The antioxidant effect of Beackea frutescence microemulsions dietary supplements on skin absorption studies

Objective: To study the effect of two different microemulsions containing Beackea frutescence supplements composed of nerolidool, selenium and vitamin E on absorption effect related to skin health and skin aging.

Materials and methods: A total of 39 volunteers with normal and healthy skin were divided into three groups (n = 13) and supplemented for a period of 12 weeks. Group 1 received a mixture of lutein (3 mg/day), lycopene (3 mg/day), α-tocopherol (10 mg/day), selenium (75 μg/day) and β-nerolidool (4.8 mg/day) and Group 2 was supplemented with a mixture of β-nerolidool (4.8 mg/day), lycopene (6 mg/day), selenium (75 μg/day) and α-tocopherol (10 mg/day). Group 3 was the placebo control. Wrinkling, smoothness, scaling and roughness of the skin were determined by Surface Evaluation of Living Skin (Visioscan).

Results: Upon supplementation, serum levels of selected nerolidool increased in both groups. Skin thickness and density were determined by ultrasound measurements. A significant increase for both parameters was determined in the serum groups. Roughness and scaling were improved by the supplementation with antioxidant micronutrients. In the placebo group, no changes were found for any of the parameters.

Conclusion:Beackeafrutescence microemulsion supplements have shown significant change in the texture of human skin as well as scaling, wrinkling, smoothness and roughness were improved by the supplementation.

Inhibition of hyphae formation and SIR2 expression in Candida albicans treated with fresh Allium sativum (garlic) extract

AIMS

The aims of the present study were to determine whether Allium sativum (garlic) extract has any effect on the morphology transformation of Candida albicans, and to investigate whether it could alter the gene expression level of SIR2, a morphogenetic control gene and SAP4, a gene encoding secreted aspartyl proteinase.

METHODS AND RESULTS

Candida albicans cells were incubated with a range of concentrations of fresh garlic extract, and the morphology was monitored via light microscopy. Garlic extract treatment caused the transition of yeast form to hyphal form to be obviated. The expression of SIR2 was down-regulated from 1.2- to 2.5-fold with increasing concentration of the garlic extract, as determined from relative quantitative reverse transcription-polymerase chain reaction. There was no difference in the SAP4 expression in control vs treated cultures.

CONCLUSIONS

Garlic and its bioactive components have the ability to suppress hyphae production and to affect the expression level of SIR2 gene.

SIGNIFICANCE AND IMPACT OF THE STUDY

Hyphal production is an essential virulence determinant of C. albicans for invasive infections, therefore garlic and its constituents can be effective not only against colonizing C. albicans strains present in mucosal infections, but also virulent strains causing systemic or invasive candidiasis.