Novel C-type lectin mediated non-specific cytotoxic cells killing activity through NCCRP-1 in nile tilapia (Oreochromis niloticus).

Non-specific cytotoxic cells (NCCs) are vital immune cells involved in teleost's non-specific immunity. As a receptor molecule on the NCCs' surface, the non-specific cytotoxic cell receptor protein 1 (NCCRP-1) is known to play a crucial role in mediating their activity. Nevertheless, there have been limited studies on the signal molecule that transmits signals via NCCRP-1. In this study, a yeast two-hybrid (Y2H) library of tilapia liver and head kidney was constructed and subsequently screened with the bait vector NCCRP-1 of Oreochromis niloticus (On-NCCRP-1) to obtain a C-type lectin (On-CTL) with an interacting protein sequence. Consequently, the full-length sequence of On-CTL was cloned and analyzed. The expression analysis revealed that On-CTL is highly expressed in the liver and is widely distributed in other tissues. Furthermore, On-CTL expression was significantly up-regulated in the brain, intestine, and head kidney following a challenge with Streptococcus agalactiae. A point-to-point Y2H method was also used to confirm the binding between On-NCCRP-1 and On-CTL. The recombinant On-CTL (rOn-CTL) protein was purified. In vitro experiments demonstrated that rOn-CTL can up-regulate the expression of killer effector molecules in NCCs via its interaction with On-NCCRP-1. Moreover, activation of NCCs by rOn-CTL resulted in a remarkable enhancement in their ability to eliminate fathead minnow cells, indicating that rOn-CTL effectively modulates the killing activity of NCCs through the NCC receptor molecule On-NCCRP-1. These findings significantly contribute to our comprehension of the regulatory mechanisms governing NCC activity, paving the way for future research in this field.

Complete mitochondrial genome and assembled DNA barcoding analysis of Lutjanus fulgens (Valenciennes, 1830) and its comparison with other Lutjanus species.

Lutjanus fulgens (Valenciennes, 1830) is a teleost species classified under the family Lutjanidae which is a native of the Eastern Atlantic Ocean. Though highly commercialized due to its abundance and good taste, the production output has declined in recent years. This is an indication of the need for effective management and conservation measures. However, accurate species identification will ensure strategic management and conservation measure. DNA-based species identification has proven its reliability in this regard via precise species identification. Several researchers have confirmed the accuracy of DNAbarcode as a species identification tool as well as species phylogeny analysis based on both the complete mitogenome and COI gene. Currently, nine specimens of L. fulgens were sampled from Ghana and subjected to DNA-based analysis, namely, complete mitochondrial DNAand COI gene (DNA barcoding) analyses. The mitogenomic result revealed that L. fulgens is made up of a 16,500 base pairs (bp) mtDNA which consists of 22 transfer RNAs, 13 protein-coding genes, and two ribosomal RNAs (GenBank Accession Number: MN398650). Furthermore, a sequence polymorphism analysis of the COIgene (MN986442-MN986450) detected two haplotypes. These haplotypes were both collected from the same fish landing site which suggests a possible cryptic linage diversity in the L. fulgens population at Vodza. According to the phylogeny examination, a close taxonomic relationship exists between L. fulgens and Lutjanus buccanella caused by a recent evolution termed as sympatric speciation. This study serves as a novel study for this species, building the foundation for future molecular-based study for this species and as a DNA barcode reference data.

Impact of dietary oil replacement on muscle and liver enzymes activity, histomorphology and growth-related genes on Nile tilapia.

This study evaluated the efficacy of replacing dietary fish oil (FO) with vegetable oils (virgin coconut and corn oil) on enzyme activities (glycolytic, oxidative and lipid metabolites), mRNA expression of lipid metabolic genes and histomorphology of liver and intestine in O. niloticus. O. niloticus (6.07 ±â€¯0.07 g) was fed six experimental diets where fish oil (FO) served as the control diet, and then was supplemented by dietary oils; virgin coconut oil (VCO) {3%FO + 3%VCO; 3FVCO}, and corn oil (CO) {3%FO + 3%CO; 3FCO}, 6%VCO (VCO), 6%CO (CO) and 6%VO {3%VCO + 3%CO; VO}. Growth performances measured indicated fish fed diet 3FCO had higher weight gain (WG) and specific growth rate (SGR). Fish fed diet 3FCO recorded the highest activities in lactate dehydrogenase (LDH), pyruvate kinase (PK), citrate synthase (CS), cytochrome coxidase (COX), malic enzymes (ME) and lipoprotein lipase (LPL) respectively. Stearoyl-CoA desaturase (SCD1) was upregulated in groups fed diets 3FVCO and 3FCO. Also, groups fed diet VCO and CO expressed highly in LPL, whereas, elongase of very long-chain fatty acids (ELOVL-5) was not influenced by the lipid sources. Histological representations in the liver were highly impacted in vegetable diets where lipid accumulation was higher except those fed VCO. However, in the digestive tract from distal to middle and posterior, the same group (VCO) exhibited altered morphological structure as those fed diet 3FCO were similar to FO. The study shows that, corn oil in diets relates positively to growth and enzymatic activities which becomes evident in their depositions in liver and functional intestinal tracts. This study indicates dietary alternatives may cause alterations in lipid metabolic pathways (LPL and SCD1) involved in fatty acid transport. As such, polyunsaturated fatty acid (PUFA) rich diets (CO) based on this study results increases metabolic activities involving especially the production, distribution and consumption of adenosine triphosphate (ATP) in O. niloticus.

Assessing the economic impact of climate change in the small-scale aquaculture industry of Ghana, West Africa.

Background: Aquaculture in Ghana is very profitable, but faces sustainability challenges. This paper assessed the impact pathways by which climate change affects the production and profitability of small-scale aquaculture in Ghana. The study analyzed and compared the economic value of smallholder fish farms with and without the incidence of climatic parameters. Methods: Simple random sampling and purposive sampling techniques were used to select the study area and farms. A total of 30 farmers were interviewed using a questionnaire-based interview. Additionally, using document analysis, observation, and data on farms' production input and output values, the economic impact of climate change on fish farms was assessed. Results: Extreme temperatures, erratic rainfall, floods, drought, storm and erosion are prevalent in fish farms. Available data shows a decrease of 53.4% of small-scale revenue, a 6.9% reduction in small-scale aquaculture value from GH¢ 83,000 to GH¢ 120,000 reducing fish supply by 25%. The findings indicate that the profitability, economic value, and livelihoods of the small-scale aquaculture industry is greatly affected by changes in climate. The incidence of floods, drought, erratic rainfall, erosion, and extreme temperature synergistically induce poverty. The implication on the livelihoods of fish farming households is very alarming and poses a serious threat to food security in the country. Conclusion: Based on the findings, this study concludes that; floods, rainfall temperature, and drought are the major climatic factors affecting the profitability and sustainability of the pond aquaculture industry. The preliminary recommendation is that there is an urgent need to map out flood-free zones close to perennial water bodies to overcome floods and droughts. Planting trees around ponds to create a micro-ecologies ideal for fish culture and also the construction of water storage facilities and proper dyke design would overcome drought and erosion issues. The adaptive capacity of fish-farmers must be built.