Unveiling the biofloc culture potential: Harnessing immune functions for resilience of shrimp and resistance against AHPND -causing Vibrio parahaemolyticus infection.

In shrimp aquaculture, disease mitigation may be accomplished by reducing the virulence of the pathogen or by boosting the shrimp's immunity. Biofloc technology is an innovative system that improves the health and resistance of shrimp to microbial infections while providing a viable option for maintaining the quality of culture water through efficient nutrient recycling. This review aimed at demonstrating the efficacy of the biofloc system in boosting the immune responses and protective processes of shrimp against Vibrio parahaemolyticus infection, which is known to cause Acute Hepatopancreatic Necrosis Disease (AHPND). Numerous studies have revealed that the biofloc system promotes the immunological capability of shrimp by raising multiple immune -related genes e.g. prophenoloxidase, serine proteinase gene, ras-related nuclear gene and penaeidinexpression and cellular and humoral responses such as hyperaemia, prophenoloxidase activity, superoxide dismutase activity, phagocytic activity; the protection and survival of shrimp when faced with a challenge from the V. parahaemolyticus strain have been enhanced. Furthermore, the use of the biofloc system improves water quality parameters and potentially bolstering their immune and overall health to effectively resist diseases; hence, promotes the growth of shrimp. The present review suggests that biofloc can serve as an effective therapy for both preventing and supporting the management of probable AHPND infection in shrimp culture. This approach exhibits potential for the progress of sustainable shrimp farming, higher productivity, and improved shrimp health.

Gene expression analysis of Ruditapes philippinarum haemocytes after experimental Perkinsus olseni zoospore challenge and infection in the wild.

The production of Manila clam (Ruditapes philippinarum) is seriously threatened by the protistan parasite Perkinsus olseni. We characterized and compared gene expression of Manila clam haemocytes in response to P. olseni in a time-course (10 h, 24 h, 8 d) controlled laboratory challenge (LC), representing the first step of infection, and in a more complex infection in the wild (WI), using a validated oligo-microarray containing 11,232 transcripts, mostly annotated. Several immune-genes involved in NIK/NF-kappaB signalling, Toll-like receptor signalling and apoptosis were activated at LC-10 h. However, down-regulation of genes encoding lysozyme, histones, cathepsins and heat shock proteins indicated signals of immunodepression, which persisted at LC-24 h, when only down-regulated genes were detected. A rebound of haemocyte activity occurred at LC-8 d as shown by up-regulation of genes involved in cytoskeleton organization and cell survival. The WI study showed a more complex picture, and several immune-relevant processes including cytoskeleton organization, cell survival, apoptosis, encapsulation, cell redox- and lipid-homeostasis were activated, illustrating the main mechanism of host response. Our results provide useful information, including potential biomarkers, to develop strategies for controlling Manila clam perkinsosis.

De novo transcriptome assembly of Perkinsus olseni trophozoite stimulated in vitro with Manila clam (Ruditapes philippinarum) plasma.

The protistan parasite Perkinsus olseni is a deadly causative agent of perkinsosis, a molluscan disease affecting Manila clam (Ruditapes philippinarum), having a significant impact on world mollusc production. Deciphering the underlying molecular mechanisms in R. philippinarum-P. olseni interaction is crucial for controlling this parasitosis. The present study investigated the transcriptional expression in the parasite trophozoite using RNA-seq. Control and treatment (in vitro challenged with Manila clam-plasma) P. olseni trophozoite RNA were extracted and sequenced on the Illumina HiSeq 2000 instrument using a 100-bp paired-end sequencing strategy. Paired reads (64.7 million) were de novo assembled using Trinity, and the resultant transcripts were further clustered using CAP3. The re-constructed P. olseni transcriptome contains 47,590 unique transcripts of which 23,505 were annotated to 9764 unique proteins. A large number of genes were associated with Gene Ontology terms such as stress and immune-response, cell homeostasis, antioxidation, cell communication, signal transduction, signalling and proteolysis. Among annotated transcripts, a preliminary gene expression analysis detected 679 up-regulated and 478 down-regulated genes, linked to virulence factors, anti-oxidants, adhesion and immune-response molecules. Genes of several metabolic pathways such as DOXP/MEP, FAS II or folate biosynthesis, which are potential therapeutic targets, were identified. This study is the first description of the P. olseni transcriptome, and provides a substantial genomic resource for studying the molecular mechanisms of the host-parasite interaction in perkinsosis. In this sense, it is also the first evaluation of the parasite gene expression after challenge with clam extracellular products.

Water Quality, Nutritional, Hematological, and Growth Profiles of Ompok pabda Fish Fry Reared in Biofloc Technology and Traditional Culture System with Different Stocking Densities.

The present study evaluated water quality, immune responses, nutritional condition, and production of Ompok pabda fry (0.29-0.31 g) reared in a Biofloc technology (BFT) system (C:N = 20:1; molasses as organic carbon source), compared to the traditional culture system (TS; farmer's practice). The experiment had stocking densities for the treatments of 17 (TS1) and 22 (TS2), 17 (BFTS1), 22 (BFTS2), and 27 (BFTS3) fish/m2. The fishes were fed at 3-10% of their body weight, and reared in cemented tanks for 90 days. Regarding water quality, dissolved oxygen (DO), pH, and total ammonia nitrogen (TAN) levels varied significantly (p < 0.05) between the traditional and BFT tanks. The highest specific growth rate (SGR) was in the BFTS1-reared fishes (4.11 ± 0.17) but the lowest was in the TS2-fish (3.51 ± 0.05). The fish reared in BFT had higher levels of protein, lipids, polyunsaturated fatty acids, essential amino acids, hematocrit, and neutrophil than the fish reared in TS tanks. Moreover, 98.33% survival was recorded in the BFTS1 while 86.67% was in the TS2. The highest BCR was estimated for the BFTS2 (1.22). Taking into account FCR and BCR values, a stocking density of 22 fry/m2 is likely practicable for an O. pabda BFT system.

New insights into the Manila clam - Perkinsus olseni interaction based on gene expression analysis of clam hemocytes and parasite trophozoites through in vitro challenges.

The Manila clam (Ruditapes philippinarum) is the bivalve species with the highest global production from both fisheries and aquaculture, but its production is seriously threatened by perkinsosis, a disease caused by the protozoan parasite Perkinsus olseni. To understand the molecular mechanisms underlying R. philippinarum-P. olseni interactions, we analysed the gene expression profiles of in vitro challenged clam hemocytes and P. olseni trophozoites, using two oligo-microarray platforms, one previously validated for R. philippinarum hemocytes and a new one developed and validated in this study for P. olseni. Manila clam hemocytes were in vitro challenged with trophozoites, zoospores, and extracellular products from P. olseni in vitro cultures, while P. olseni trophozoites were in vitro challenged with Manila clam plasma along the same time-series (1 h, 8 h, and 24 h). The hemocytes showed a fast activation of the innate immune response, particularly associated with hemocyte recruitment, in the three types of challenges. Nevertheless, different immune-related pathways were activated in response to the different parasite stages, suggesting specific recognition mechanisms. Furthermore, the analyses provided useful complementary data to previous in vivo challenges, and confirmed the potential of some proposed biomarkers. The combined analysis of gene expression in host and parasite identified several processes in both the clam and P. olseni, such as redox and glucose metabolism, protease activity, apoptosis and iron metabolism, whose modulation suggests cross-talk between parasite and host. This information might be critical to determine the outcome of the infection, thus highlighting potential therapeutic targets. Altogether, the results of this study aid understanding the response and interaction between R. philippinarum and P. olseni, and will contribute to developing effective control strategies for this threatening parasitosis.