Fisheries & Aquatic Life

Applicability of an in-house Chelex-100 DNA isolation method for extracting genetic material from sterlet (Acipenser ruthenus) embryos

Dorota Fopp-Bayat, Tomasz Raczyński, Marcin Kuciński — Sun, 31 Mar 2024 00:00:00 +0100

Efficient, cost-effective DNA extraction methods are crucial for molecular research on sturgeon embryos given that substantial sample sizes must frequently be analyzed in short periods of time. The high lipid and carbohydrate contents of sturgeon embryo yolk sacs mean that obtaining genetic material of sufficient quality is challenging. The predominant methods used include tissue/cell lysis, organic extraction, purification on spin columns, and ethanol precipitation. However, these methods are expensive and time-consuming, which significantly limits the throughput of PCR-based molecular analyses. In the present study, we evaluated the usefulness of an in-house Chelex-100 DNA extraction method on sterlet (Acipenser ruthenus) embryos at the neurula developmental stage (48 hours post fertilization) and compared it with two other commercial silica membrane-based kits for isolating genetic material–NucleoSpin Tissue® (Macherey Nagel, Duren, Germany) and Sherlock AX (A&A Biotechnology, Gdynia, Poland). The yield and quality of nucleic acid, its suitability for PCR amplification, and the total cost and complexity of the extraction methods were evaluated and compared. Our results indicated that the in-house Chelex-100 is inexpensive and can be used as an effective high-throughput method of DNA isolation for sterlet embryos.

Spatial and temporal patterns of fish assemblages in Lake Nokoué and the Porto-Novo Lagoon (Benin, West Africa)

Sun, 31 Mar 2024 00:00:00 +0100

Fish distribution in the lagoon complex of Lake Nokoué and Porto-Novo Lagoon is poorly documented. The lagoon complex is of particular interest because of its contribution to the local supply of animal protein. The fish communities in the complex were studied monthly between January and December 2015 at six sampling sites using two sets of gillnets with varying mesh sizes. The study applied a non-linear self-organizing map (SOM) method to classify the sampling sites based on the composition of fish assemblages, and an index of indicator value (IndVal) was calculated for each species identified. In total, 58 species from 49 genera and 34 families were cataloged with 45 species observed in Lake Nokoué and 48 in the Porto-Novo Lagoon. Notably, 35 species were common to both water bodies. The analysis revealed a dominance of occasional continental (20.7%) and strict estuarine species (20.7%). The SOM analysis suggested a tripartite structure of the fish communities, largely influenced by the geographical positioning of the sampling sites. The IndVal method identified 28 indicator species in the typical assemblages delineated by the SOM approach. The study highlights the importance of these indicator species for the conservation efforts aimed at sustaining the ichthyofauna of the lagoon complex.

Preliminary rearing outcomes of Siberian sturgeon, Acipenser baerii Brandt, juveniles in autonomous hatching and rearing modules

Iwona Piotrowska, Michał Kozłowski — Sun, 31 Mar 2024 00:00:00 +0100

This study analyzed the rearing indicators of Siberian sturgeon (Acipenser baerii) juveniles reared in tanks of different shapes and at various stocking densities. Rearing was conducted in autonomous hatching and rearing modules. Fish of an average body weight of 47.3±1.0 g were divided into four experimental groups: C_L, R_L, C_H, and R_H, which differed in stocking density (20 specimens and 50 specimens) and tank shape (C – circular, R – rectangular). The experiment ran for 28 days. Two-factor analysis indicated that lower stocking density significantly affected the final body weight of juvenile Siberian sturgeon, while tank shape had no effect on growth. The results of the current study on rearing Siberian sturgeon juveniles indicated that tanks of different shapes can be applied, but faster growth was obtained at a lower stocking density.

Effects of dietary supplementation with mannan-rich oligosaccharides and solid-state fermented Aspergillus niger on the growth performance of juvenile Asian seabass, Lates calcarifer

Sun, 31 Mar 2024 00:00:00 +0100

Feed additives are gaining popularity as dietary supplements with the potential to support growth, immune competence, and the general health of aquaculture species. This study aimed to evaluate growth performance and feed utilization in juvenile Asian seabass, Lates calcarifer, fed experimental diets containing enzymes derived from the solid-state fermentation (SSF) of Aspergillus niger and mannan oligosaccharides (MOS), both individually and in combination. Fish were fed six experimental diets: control (no additives), SSF (0.025% & 0.05%), MOS (0.1% & 0.2%), and combined SSF (0.025%) + MOS (0.05%). The feeding trial was conducted for ten weeks in triplicate for each experimental diet consisting of 51 fish in 120 L tanks. Following the collection of growth performance metrics, proximate analysis of muscle and feces samples was performed, and all datasets were statistically analyzed with One-way ANOVA. The results showed that the highest specific growth rate (SGR = 1.29%) and lowest feed conversion rate (FCR = 1.0) were obtained by fish fed the diet supplemented with SSF (0.025%) + MOS (0.05%). The synergistic effects of SSF as an exogenous enzyme source and MOS in supporting gut health likely facilitated enhanced nutrient digestibility and absorption, which supported the growth of juvenile Asian seabass.

Modulation of oxidative stress biomarkers and lysosomal functioning in gills and liver of rainbow trout (Oncorhynchus mykiss Walbaum) fed a diet supplemented with yeast β-glucans

Natalia Kurhaluk, Joanna Grudniewska, Halina Tkaczenko — Sun, 31 Mar 2024 00:00:00 +0100

The present study was performed to investigate the effects of dietary yeast β-1,3/1,6-D-glucans after 15-, 30-, and 45-day feeding periods on the development of oxidative stress, antioxidant defenses, and lysosomal functioning in gills and hepatic tissue of rainbow trout, Oncorhynchus mykiss (Walbaum). The fish were fed a control diet or an experimental diet containing the supplement Yestimun^® at a dose of 1% in the basal feed (with 85% content of β-1,3/1,6-glucans). On days 15, 30, and 45 of the experiment, the following were analyzed in gills and hepatic tissue: oxidative stress biomarkers (2-thiobarbituric-acid-reacting substances [TBARS]); aldehydic and ketonic derivatives of oxidatively modified proteins; activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx); total antioxidant capacity (TAC); activities of lysosomal enzymes (alanyl aminopeptidase [AAP], leucyl aminopeptidase [LAP], acid phosphatase [AcP], β-N- acetylglucosaminidase [NAG]). The dietary β-glucans stimulated CAT, GPx, LAP, and AcP activities in gills and hepatic tissue compared to the control group; however, the opposite trend was observed in TAC levels in gills on days 30 and 45. The present study suggests that β-glucans can enhance immune response, antioxidant capacity, and lysosomal functioning effectively in rainbow trout.