Freshwater Prawn Research Articles

The Production of Fairy Shrimp as Live Food for Aquatic Animals and Transfer to Farmers

Fairy shrimps are zooplankton, a small crustacean with high nutritional value and carotenoids. Fairy shrimps are aquatic animals that feed on both living and non-living food by filtering. In Thailand, there are 3 species of fairy shrimps, namely Streptocephalus sirindhornae, Branchinella thailandensis, and Streptocephalus siamenesis. The three species of fairy shrimps exhibit distinct characteristics in terms of size, color, and egg morphology. There are 3 types of fairy shrimp culture in Thailand, namely, cement ponds, clay ponds, and hapas, which are adult fairy shrimp cultures. Both living and non-living forms of fairy shrimps are used by freezing. The usage of fairy shrimps come in both living and non-living, frozen forms. Fairy shrimps are fed as food for beautiful aquatic animals such as goldfish, cichlids, etc. They are also used as food pellets to feed aquatic animals such as giant freshwater prawns, Rad tilapia fish, etc. Therefore, it can be concluded that fairy shrimps have a significant potential as a valuable food source for both larval and adult aquatic organisms. Consequently, the widespread dissemination of knowledge about fairy shrimp aquaculture and utilization can greatly enhance their adoption in the aquaculture industry, thereby promoting sustainability.

Proteomic profiling of the Macrobrachium rosenbergii nodavirus infection: A study of early to late-stage infection in vitro

The Macrobrachium rosenbergii nodavirus (MrNV), belonging to the Nodaviridae family, is responsible for a deadly infection in freshwater prawns, especially impacting the post-larvae of Macrobrachium rosenbergii with a mortality rate reaching 100 %. Recent research has shed light on the typical process of MrNV trafficking within the host, illustrating how the virus navigates through cells as the infection advances and the subsequent cellular alterations. Yet, the specific cellular pathways disrupted by MrNV, leading to these alterations, are underexplored. Furthermore, the precise effects of the MrNV capsid protein, known for its strong immune response, on the host cells are not well understood. This study seeks to clarify these impacts by analysing and comparing the protein expression profiles in healthy, MrNV virus-like particle (VLP) invaded, and MrNV-infected Sf9 cells over a 24-h period using a mass spectrometry based proteomics approach. Our findings show that the protein expression in MrNV VLP-invaded and MrNV-infected Sf9 cells during the mid-infection stages is similar, involving key signalling pathways like the eukaryotic translation system, cell cycle, actin cytoskeleton regulation, and the mTOR pathway. However, changes in protein expression for key proteins such as 40S and 60S ribosomal subunits, 14–3-3 protein epsilon, and tubulin beta chain persisted only within the MrNV-infection group whilst the protein expression in the VLP-invasion group reverted to baseline levels over time, underscoring the transient nature of VLP effects due to their inability to replicate. Additionally, a reduction in peroxiredoxin levels was observed in the later stages of MrNV infection, indicating a potential viral strategy to trigger apoptosis and release virions. Our results suggest that MrNV increases expression of 40S ribosome activity to boost viral protein synthesis while suppressing 60S ribosome expression, which impedes the synthesis of host proteins. MrNV also appears to extend the lifespan of host cells by interfering with their cell cycle and blocking apoptotic pathways, thus facilitating viral replication. This research enhances our comprehension of MrNV's infectious mechanism, delineates the pathways exploited by the virus, and identifies crucial molecular targets for potential therapeutic intervention.

Kalman Filter-Based Data Stabilization for an Automated Water Quality Monitoring System in Macrobrachium Rosenbergii Larvae Culture

Manual monitoring and management of water quality parameters in Macrobrachium Rosenbergii (freshwater prawn) larval culture are labourintensive, time-consuming, and susceptible to human error. This research aims to develop and evaluate an automated water quality monitoring system for freshwater prawn larval culture, with a specific emphasis on data stabilization. An ESP32 microcontroller is implemented to allow remote communication using an internet connection. The system continuously monitors critical parameters using sensors such as temperature, pH, turbidity, and Total Dissolved Solids (TDS), facilitating remote real-time data acquisition. The Message Queuing Telemetry Transport (MQTT) publish-subscribe protocol is employed for seamless communication between the microcontroller and the monitoring dashboard. A Kalman filter is integrated into the system, enabling real-time sensor noise reduction and dynamic adaptation to changes. The filtered data are displayed remotely using a Node-RED dashboard with graphical representations. The implementation of the ESP32 microcontroller with the MQTT protocol and Node-RED has proven to be a robust platform for seamless data communication and presentation. Integration of the Kalman Filter significantly mitigates fluctuations in sensor readings. This is further proven by comparisons of the filtered data with known-good sensors, which have shown minimal to acceptable error percentages between 1% - 8.5%, where the error can mainly be attributed to environmental factors. Overall, this study has established a framework that can contribute to improving aquaculture practices and promoting environmental sustainability infreshwater prawn culture operations. The validated system provides valuable insights that assist farmers in facilitating a more efficient prawn culture operation.

Postprandial regulation of glucose metabolism and insulin signaling pathways in Macrobrachium rosenbergii

To better understand postprandial glucose metabolic mechanisms in crustaceans, the pathways involved in glucose transport, breakdown, synthesis, and regulation were investigated in the giant freshwater prawn Macrobrachium rosenbergii after feeding. Prawns were fasted for 48 hours and then refed to satiation. Glucose and glycogen contents, along with the transcriptional levels of glucose metabolism-related genes, were measured at 0, 1, 3, 6, and 10 hours after feeding (HAF). Plasma glucose levels peaked at 3 HAF and returned to basal levels by 6–10 HAF. Hepatopancreas glucose followed a similar trend, except for a notable increase at 10 HAF, suggesting gluconeogenesis at this time point. Expression analysis of glucose transporter genes in hepatopancreas revealed a significant upregulation of GLUT1 at 3, 6, and 10 HAF, while GLUT2 showed significant decreases only at 6 HAF. Glycolysis-related genes (GK and PK) exhibited transient increases post-feeding, whereas the gluconeogenesis-related gene FBP was initially suppressed, with expression recovering from 6 HAF onward. The glycogenesis-related gene GS was significantly upregulated at 3, 6, and 10 HAF, correlating with increased glycogen levels in the hepatopancreas. Conversely, the expression of the glycogenolysis-related gene GDE was inhibited after feeding, along with a decrease in the glycogenesis inhibitory gene GSK3. Genes in the insulin signaling pathway (ILP, PI3KCa, and AKT) were upregulated post-feeding, peaking at 3 HAF and subsequently declining. These results suggest that feeding stimulates the insulin signaling pathway and GLUT1 to transport excess glucose, inducing glycolysis and hepatopancreatic glycogenesis, while inhibiting gluconeogenesis and glycogenolysis.

Biological effects of glyphosate and emamectin benzoate based pesticides on the freshwater prawn Macrobrachium macrobrachion juveniles

Biological effects of glyphosate and emamectin benzoate based pesticides on the freshwater prawn Macrobrachium macrobrachion juveniles

The Dmrt1 gene: Identification and functional analysis in testicular development and spermatogenesis in the freshwater prawn, Macrobrachium nipponense

Products of the Dmrt gene family are known to harbor a zinc-finger DM domain and play crucial roles as transcription factors in various physiological processes, including sexual differentiation, gonadal development, and spermatogenesis. Despite their significance, research on the Dmrt family in Crustacea remains limited. In the present study, we identified a member of this gene family in the freshwater prawn Macrobrachium nipponense and designated it as MnDmrt1. We investigated its expression patterns across different tissues, potential target genes, and its influence on testicular development and protein interactions within the testes. Our findings revealed that MnDmrt1 encodes a protein composed of 252 amino acids that is predominantly expressed in the testes and localized in spermatogonia, spermatocytes, and spermatozoa. Silencing MnDmrt1 disrupts spermatogenesis and alters the expression levels of several key genes associated with testicular development, spermatogenesis, and sex reversal, such as Dmrt11E, Insulin receptor, and Masculinizer. Additionally, we identified 59 proteins that interact with MnDmrt1 in the testis using pull-down assays and liquid chromatography-tandem mass spectrometry. Notably, the eyestalk negatively regulates the expression level of MnDmrt1 in the testis. Collectively, these results underscore the essential role of MnDmrt1 in testicular development and spermatogenesis in M. nipponense.

Light spectrum effects on giant freshwater prawns, Macrobrachium rosenbergii: Larval development, survival and preferences

The objective of this study was to evaluate the influence of different light spectra on growth, development indices, survival and color preferences in Macrobrachium rosenbergii larvae. First (trial 1, 25 days), prawns (100 larvae/L) were randomly allocated to 30 cylindrical plastic containers (1 L). This trial was designed with five treatments (light spectra) and six replications: red light, blue light, green light and white light or absence of light (controls) in the 12:12 light:dark (LD) cycle. Next (trial 2), 30 groups of five larvae in two different development stages (VII and XI) were allocated to a system of compartments with different lights: white, red, blue or green. This system was connected by tubes to enable light spectra choices. Final weight, weight gain, consumption and metamorphosis significantly improved under the white light condition versus the other tested groups (p<0.05). Survival, the Larval Stage Index, the Larval Condition Index and final biomass clearly improved under the white light condition (p<0.05). Conversely, the red light and no light conditions obtained unsatisfactory results. White light was preferred in larvae stage VII (p<0.05), but this behavior changed to blue when prawns reached life stage XI (p<0.05). These findings suggest that white light may be the best choice to optimize larval growth and survival, while color preferences may vary with development stage.

Chromosome level genome assembly of giant freshwater prawn (Macrobrachium rosenbergii)

The giant freshwater prawn (Macrobrachium rosenbergii) has many advantages in aquaculture, such as fast growth rate, short breeding cycle and good nutrition, which makes it a freshwater shrimp with high economic value. Herein, high-quality chromosome-level genome of both female and male prawns were obtained by combining Illumina paired-end sequencing, PacBio single molecule sequencing technique and High-through chromosome conformation capture (Hi-C) technologies. In ZZ male prawn, a final contig assembly of 3118.58 Mb with a N50 length of 956,237 bp was obtained. In WW female prawn, a final contig assembly of 3333.31 Mb with a N50 length of 1,143,555 bp was obtained. The assembled genome sequences from prawns were anchored to 59 chromosomes. Moreover, the sex chromosomes including W chromosome and Z chromosome were generated in prawn with the length of 36.23 Mb and 27.33 Mb, respectively. The sequence similarity of Z chromosome and W chromosome reached to 74.90%. The high-quality genome resource will be useful for further molecular breeding and functional genomic research of giant freshwater prawns.

NEW RECORD SPECIES OF GIANT FRESH WATER SHRIMP FROM THE DOWNSTREAM OF SERAYU RIVER

Indonesia is characterized by great diversity of freshwater shrimp, consisting of several islands due to the geographical location on the equator. A recent investigation conducted in Central Java has identified Serayu River as the major habitat of freshwater shrimp genus Macrobrachium. Therefore, this research aimed to determine the type of giant freshwater shrimp found downstream of Serayu River using explanatory method. The experiment was conducted for one year (January - December 2023) and the results found two freshwater giant prawn species, namely Macrobrachium rosenbergii and Macrobrachium spinipes. Moreover, this research is the first record of M. spinipes based on the Cytochrome C oxidase Subunit I (CO1) gene. The mtDNA segment of M. rosenbergii was 631 bp (base pairs) (GenBank accession: LC813231.1), while M. spinipes was 616 bp (GenBank accession: PP735157.1). M. spinipes and M. rosenbergii downstream of Serayu River showed similar locations and characteristics. Genetic distance conducted on 15 species of the genus Macrobrachium showed that giant freshwater prawn serayu had a matrix value of 0.09 - 0.18. Genetic analysis conducted with GenBank indicated that M. spinipes showed significant differences from other species, suggesting the natural dispersal of juvenile through currents across Wallace Line. This research also found that M. rosenbergii was similar to M. dacqueti and related to M. malcolmsonii, while M. spinipes was close to M. suphanense. To support these results, recommendation was made to explore further the rivers in the western part of Java, Indonesia.

Effects of freshness of poultry by-product meal on the growth performance, immune response, and hepatopancreatic health of Macrobrachium rosenbergii

A 73-day feeding trial was conducted to determine the effects of the freshness of poultry by-product meal on the growth performance, immune response and hepatopancreatic health of giant freshwater prawn, Macrobrachium rosenbergii. Three semi-purified diets were formulated containing 2.5 % poultry by-product meal with different TVB-N value, designated as L group (untreated poultry by-product meal, TVB-N 10 mg/100 g, i.e., dietary TVB-N 55 mg/100 g), M group (TVB-N 300 mg/100 g, i.e., dietary TVB-N 60 mg/100 g), and H group (TVB-N 450 mg/100 g, i.e., dietary TVB-N 68 mg/100 g), and fed to three groups of prawns (initial weight: 0.82 ± 0.01 g), respectively. Results showed that the weight gain rate (WGR) and specific growth rate (SGR) of prawns significantly decreased with the TVB-N value increased (P < 0.05). The survival rate (SR) and hepatosomatic index (HSI) of prawns in group M and group H were significantly decreased (P < 0.05), while the feed conversion ratio (FCR) was significantly increased (P < 0.05). In addition, the lipase (LPS) and α-amylase (α-AMS) activity of prawns in group L was significantly higher than that in group H (P < 0.05). With the poultry by-product meal TVB-N value increased, the activity of total superoxide dismutase (T-SOD) and glutathione S-transferase (GST) was significantly decreased. RT-qPCR results showed that the expression of bok in group H was significantly higher than that in group L and group M (P < 0.05), the expressions of caspase3, caspase9, bax, and nf-κb in group H were significantly higher than that in group L (P < 0.05). High temperature stress and ammonia nitrogen stress significantly decreased the cumulative survival rate of prawns in group M and group H. Conclusively, it is necessary to guarantee the freshness of the ingredients in prawn formulated diets, and the TVB-N value of diets is recommended not to exceed 60 mg/100 g.

Changes in Water Quality and Soil Property in the Rice–Freshwater Animal Co-Culturing System

This study investigated the effects of integrating various fish species in a rice field co-culture system on water quality and soil properties. The species included common carp (Cyprinus carpio), Nile tilapia (Oreochromis niloticus), silver barb (Barbonymus gonionotus), snakeskin gourami (Trichopodus pectoralis), and giant freshwater prawn (Macrobrachium rosenbergii). The key water quality parameters measured included water temperature, dissolved oxygen, pH, transparency, ammonia, and nitrite. Soil properties were evaluated through pH, electrical conductivity, organic matter, nitrogen, phosphorus, and potassium. All the selected aquatic animals showed high adaptability in co-culture systems, with survival rates exceeding 80%. Additionally, rice yields increased by approximately 16%, with the highest yield observed in plots stocked with prawns. The results indicated that the presence of aquatic animals enhanced nutrient cycling, leading to significant improvements in both water quality and soil fertility. Differences in water quality and soil properties throughout the culture period were specific to the species present. These findings suggest that rice-fish co-culture systems serve as an effective nature-based solution for enhancing productivity, sustainability, and food security.

Potential of integrated multitrophic aquaculture to make prawn farming sustainable in Bangladesh

Farmed freshwater prawn (Macrobrachium rosenbergii) and black tiger shrimp (Penaeus monodon) comprise a significant portion of Bangladesh’s seafood exports, raising concerns about their environmental impacts. Freshwater prawn farms, which require a relatively high amount of feed supply, release 1.0 MT CO2-equivalents/year, equating to 18.8 kg CO2e/MT prawn, contributing significantly to global warming and climate change risks. Integrated Multi-Trophic Aquaculture (IMTA) offers an alternative farming method to conventional prawn farming systems, as it minimizes greenhouse gas (GHG) emissions and climate change impacts. Systematically reviewing 112 scientific articles on IMTA, this article offers recommendations for adopting IMTA to promote sustainable freshwater prawn farming in Bangladesh. IMTA is undergoing extensive experimentation and practice in many parts of the world, offering economic benefits, social acceptability, and environmental sustainability. In addition to native prawn species, various indigenous organic extractive freshwater mollusks, and inorganic extractive plants are available which can seamlessly be used to tailor the IMTA system. Extractive organisms, including aquatic mollusks and plants within prawn farms, can capture blue carbon effectively lowering GHG emissions and helping mitigate climate change impacts. Aquatic mollusks offer feed for fish and livestock, while aquatic plants serve as a dual food source and contribute to compost manure production for crop fields. Research on IMTA in Bangladesh was primarily experimented on finfish in freshwater ponds, with the absence of studies on IMTA in prawn farms. This necessitates conducting research at the prawn farmer level to understand the production of extractive aquatic mollusk and plants alongside prawn in the prawn-producing regions of southwestern Bangladesh.

Temporal changes in streamflow can predict parasitism levels in freshwater prawns better than host traits

Abstract Understanding how changes in the hydrological regime drive parasite loads and dynamics remains a challenging issue in ecological parasitology. Temporal changes in streamflow and rainfall are key hydrological factors that could alter interactions between the parasite and host and affect parasitism levels. However, to investigate the effect of streamflow, rainfall and its mechanisms, it is important to control host traits that can also influence parasitism levels in freshwater systems. Here, we used a cymothoid‐palaemonid prawn model to test the combined effects of streamflow and rainfall accounting for host traits to predict variations in parasite loads in stream ecosystems. We collected the palaemonid prawns monthly for 2 years and measured the variation of rainfall and streamflow (i.e. stream discharge) at the time of prawn sampling. Our best model showed that streamflow can predict parasitism levels in prawns better than host traits. We found a higher prevalence and abundance of parasites in reduced streamflow compared to increased ones. We also found higher ectoparasite loads in females rather than males and occurring in autumn and winter rather than in spring and summer. Our results also showed that ectoparasite loads also suffer an effect of host body size, sex and moult stage, but not host age. Our findings show that reduced streamflow can facilitate host finding that favours parasite transmission in dry seasons and increase parasitism levels in stream systems. Temporal variability in streamflow can have a strong influence on parasite loads and dynamics compared to host traits in stream ecosystems. Identifying how interactions between aquatic invertebrates and parasites respond to variability in the hydrological regime can help to better understand and predict disease outbreaks as habitat reduction and disturbance continue in stream ecosystems.

Biofloc Technology in Improving Shellfish Aquaculture Production – A Review

Abstract Biofloc technology is instrumental in improving growth performance and yield in shellfish aquaculture, while leading to enhanced water quality through maintaining the nutrients level within a safe range. More specifically, toxic nitrogenous wastes are converted into beneficial microbial biomass known as “biofloc”, contributing to improve shellfish immune system. Among the various parameters affecting the efficiency of the process is the carbon source and C:N ratio. In light of these, the present work critically reviews the effects of biofloc systems on growth performance, immunity and diseases resistance in shellfish production. Moreover, it scrutinizes the microbial diversity and nutritional composition of biofloc. Then, the application of the technology in various shellfish cultures, including shrimp, freshwater prawn, crabs, crayfish, clam, and oyster, is presented. Overall, biofloc systems contribute to enhanced shellfish survival rate to the highest value of 96–100% for marine shrimp, 95–99% for freshwater prawn, 70–83% for crayfish, 83–100% for oyster, Crassostrea sp. and up to 2% for mud crabs larvae through substantially reducing the ammonia level in the culture (summarized in Table 1 – Table 5). Finally, the main challenges in utilizing biofloc systems, i.e., suitable aeration and mixing and microbial mechanisms involved are also explained to shed light on future research directions in the field.

Managing Complexities in Giant Freshwater Prawn Breeding Facilities in Perak, Malaysia: A Case Study

Malaysia's aquaculture industry has seen significant growth in recent years, with the giant freshwater prawn (Macrobrachium rosenbergii) emerging as a key species of economic importance. This study examines the intricate challenges faced by hatchery owners’ breeding facilities in Manjung, Perak, Malaysia as they strive to maintain and improve the brood stock production of this valuable crustacean. The research focuses on multifaceted, operational aspects of managing giant freshwater prawn hatcheries. Through a combination of field studies guided by qualitative methodology, the identification of primary obstacles encountered at Manjung breeding facilities was evaluated via current management practices. The findings revealed that hatchery owners lack adequate managerial skills in handling operational matters such as budgeting, labor utilization, utilities, marketing, and networking. The most critical factor was cost-effective sourcing of healthy, brood stock supply from local fishermen. Furthermore, the research underscores the importance of genetic diversity in broodstock populations as hatcheries struggle with inbreeding depression, necessitating the development of more robust breeding programs. From the socio-economic standpoint, a holistic approach to addressing these issues, emphasizes the need for increased collaboration between research institutions, government agencies, and private sector stakeholders. The study provided a comprehensive overview of the complexities inherent in managing giant freshwater prawn breeding facilities in Malaysia. By identifying key challenges and potential solutions, it aims to contribute to the sustainable development of this vital sector of Malaysia's aquaculture industry. The findings have implications for policy-making, industry practices, and future research directions in the field of freshwater prawn aquaculture and food security agenda.????????????????

Teknik Pendederan Udang Galah (Macrobrachium Rosenbergii) di Instalasi Budidaya Air Payau (IBAP) Probolinggo, Jawa Timur

Giant Freshwater Prawn (Macrobrachium rosenbergii) or also known as Giant Freshwater Prawn is a type of crustacean that has the largest size compared to other freshwater prawns. Giant prawns are a freshwater fisheries commodity that has great potential to be developed because it has a high selling value. This Field Work Practice (PKL) activity was carried out at the Brackish Water Cultivation Installation (IBAP) in Probolinggo City, East Java. The results of Field Work Practices (PKL) regarding giant prawn nursery techniques start from preparing nursery ponds, preparing water for rearing media, stocking juveniles, managing water tanks for rearing media, water quality management, feed management, controlling pests and diseases, as well as harvesting and packaging. Water quality measurements include DO with values obtained at 5.1-5.6 mg/L, pH 7.1-8.7, temperature reaching 24-28°C, and salinity ranging from 0-5 ppt. The feed given is Artemia salina, corn bran mixed with flakes in a ratio of 3:1, and commercial feed is in the form of pellets with a frequency of administration twice a day, namely in the morning and evening.

Genome resequencing reveals genetic status of Macrobrachium rosenbergii populations in China

The giant freshwater prawn (Macrobrachium rosenbergii) has been widely cultured in China since 1990s. In this study, 189 individuals were sampled from 10 distinct populations, including original populations introduced from abroad and domesticated strains in China, namely Florida (FD), "Nantaihu No.2" (NT), Vietnam (YN), Sri Lanka (SK), Bangladesh (ML), Thailand (TG), Taiwan (TW), "Shufeng No.1" (SF), Zhengda (ZD) and New Myanmar (NMD). The genetic diversity and population structure of these populations were analyzed based on a dataset of 300,828 genome-wide SNP loci. The population structure analysis showed that the 10 populations shared 4 ancestors, and the domestic populations (i.e., SF, ZD, TW and NT) shared a common ancestor. The phylogenetic analysis showed that the 10 populations were grouped into 4 branches, with all the domestic populations clustering together. Estimation of fixation index (Fst) values revealed relatively lower Fst values among the domestic populations, in contrast to the more significant differences observed between domestic and foreign-origin populations. Gene flow analysis revealed three significant events of genetic exchange among the 10 populations: (1) from YN to the common ancestor of FD, TG and the domestic populations, (2) from NMD to the common ancestor of TG and FD, and (3) from the common ancestor of NMD, YN, ML and SK to ZD population. In addition, selective sweep analysis, utilizing Fst and nucleotide diversity (Pi) estimations, was conducted on representative populations (i.e., ML and SF), and 7 positively selected genes were identified, including Prospero Homeobox 1 (Prox1), Forkhead Box L1 (Foxl1), Tousled Like Kinase 2 (TLK2), G Protein Subunit Alpha 14 (Gna14), Uronyl 2-sulfotransferase (Ust), MAX Network Transcriptional Repressor (Mnt) and Importin-9 (Ipo9). These findings contribute to elucidating the breeding potential of the introduced populations and provide insights into the genetic status of the domestic breeding strains of M. rosenbergii in China.

Insights on the virulence and genomic features of Lactococcus garvieae isolated from giant freshwater prawn Macrobrachium rosenbergii (de Man 1879).

Giant freshwater prawn (Macrobrachium rosenbergii (MR)) is a significant aquafarm species commercially cultured in Taiwan. Intensive farming practices have led to the outbreak of Lactococcus garvieae (LG), which causes Lactococcosis in MR. Recently, LG has re-emerged and the number of mortalities in prawn farms has increased in Taiwan. However, there is no preventative strategy described and a lack of knowledge on virulence factors and pathogenesis from LG in MR. The most virulent strain of L. garvieae from M. rosenbergii was screened invivo among seven isolates selected for infectivity testing injecting 0.1 mL of 108 CFU/mL bacterial concentration. Among the seven isolates screened, L. garvieae 109-6 resulted in 100% mortality within 3 days post-infection. Furthermore, 109-6 L. garvieae LD50 dosage from in MR was found to be 106 CFU/mL. Subsequently, the most virulent strain 109-6 was sequenced using MinIon Nanopore sequencing. Results indicated that the LG genome yielded a protein-coding of 3857 with 59 tRNA and 16 rRNA and no plasmid. Interestingly, the distribution of subsystems in the annotated genome revealed genes related to virulence, defence, and disease among LG 50 genes. Altogether, the virulent strain and its genome data revealed distinctive features of LG, which hinted toward its pathogenicity and could facilitate for better preventive strategies.

Short-term dietary supplementation of β-glucan and chitosan modulates the immune response in freshwater prawn, Macrobrachium rosenbergii (De Man, 1879)

Aim: The present study evaluates the immunomodulatory potentials of β-glucan and chitosan administered orally for 15 days to the freshwater prawn, Macrobrachium rosenbergii juveniles. Methodology: Two diets were formulated supplementing 1.5 g kg-1 and 20 g kg-1 of β-glucan (diet G) and chitosan (diet C), respectively, with a control diet (diet B). The prawns were fed twice daily at 5% biomass. At the end of the feeding trials, mRNA expression profiles of immune-related genes lipopolysaccharide- and β-1,3-glucan binding protein (LGBP) and chitinase 3 were analyzed in qPCR. Corresponding LGBP protein and chitinases/CBP (chitinase 1, chitinase 1C and obstructor E, a chitin-binding protein) protein levels were also estimated by ELISA. Results: Supplementation of the immunostimulants (diets G and C) significantly enhanced the mRNA expression of both LGBP and chitinase 3 in the hepatopancreas. The protein expression of LGBP and chitinases/CBP was also significantly increased in the serum and hepatopancreas samples of both treatment groups. Interpretation: The short-term supplementation of β-glucan and chitosan in diets demonstrated beneficial effects in M. rosenbergii by enhancing the expression of important immune molecules like LGBP and chitinases, indicating their potential applications during the period of biotic stress. Key words: β-glucan, Chitinase, Hepatopancreas, Immunostimulants, LGBP, Macrobrachium rosenbergii

Integration of Gut Microbiota with Transcriptomic and Metabolomic Profiling Reveals Growth Differences in Male Giant River Prawns (Macrobrachium rosenbergii).

The giant freshwater prawn (GFP; Macrobrachium rosenbergii), a tropical species cultured worldwide, has high market demand and economic value. Male GFP growth varies considerably; however, the mechanisms underlying these growth differences remain unclear. In this study, we collected gut and hemolymphatic samples of large (ML), medium (MM), and small (MS) male GFPs and used the 16S rRNA sequencing and liquid chromatography-mass spectrometry-based metabolomic methods to explore gut microbiota and metabolites associated with GFP growth. The dominant bacteria were Firmicutes and Proteobacteria; higher growth rates correlated with a higher Firmicutes/Bacteroides ratio. Serum metabolite levels significantly differed between the ML and MS groups. We also combined transcriptomics with integrative multiomic techniques to further elucidate systematic molecular mechanisms in the GFPs. The results revealed that Faecalibacterium and Roseburia may improve gut health in GFP through butyrate release, affecting physiological homeostasis and leading to metabolic variations related to GFP growth differences. Notably, our results provide novel, fundamental insights into the molecular networks connecting various genes, metabolites, microbes, and phenotypes in GFPs, facilitating the elucidation of differential growth mechanisms in GFPs.