This study investigated the effect of stocking density on growth performance, blood biochemical profiles, antioxidative capacity, and muscle quality of gibel carp (
Carassius gibelio
)
.
Gibel carps ...(initial body weight 57.04 ± 1.89 g) were reared at high stocking density (HSD, 10.85 kg m
−3
), medium stocking density (MSD, 5.06 kg m
−3
), and low stocking density (LSD, 1.47 kg m
−3
) for 60 days. The LSD group exhibited the highest growth rate, while HSD significantly inhibited fish growth. The muscular compositions of crude fat, crude ash, and moisture were significantly changed by stocking density, but crude protein content did not differ significantly. The stocking density altered the muscular texture profiles of gibel carp. Compared to either the HSD group or the MSD group, the highest levels of resilience and springiness occurred in the LSD group. Significant differences were observed in the levels of plasma glucose, alanine aminotransferase, aspartate aminotransferase, cholesterol, and creatinine among three groups. The fish exhibited the highest level of plasma cortisol as well as the lowest levels of triiodothyronine and thyroxine in the HSD group. The fish stocked in the LSD group showed the highest activities of superoxide dismutase, glutathione peroxidase, and catalase as well as the highest content of glutathione in liver. The significant highest total antioxidant capacity occurred in the fish stocked in the LSD group. The results showed that HSD resulted in chronic crowding stress, and exerted negative impact on growth performance, muscle quality, and antioxidative capacity of gibel carp.
The subject of the work was sports and recreational tourism to highlight the current and new opportunities for the development of a selective form of tourism in Valjevo. The focus was on providing a ...high-quality description and presentation of the tourist and sports infrastructure, existing offers of sports and recreational facilities, and events in this city. The methods of observation, interviews, and document analysis, with a specific emphasis on the analysis of websites and historical research, were used in the preparation of the paper. The conclusion is that Valjevo has sports clubs, thanks to which there is the possibility of recreation and visiting various events during the stay of tourists in this city. However, the main hindrances to the development of a selective form of tourism are accommodation facilities and outdated sports infrastructure.
Glucose and fructose play a central role in the metabolism and cellular homeostasis of organisms. Their absorption is co-mediated by two families of glucose transporters, Na
+
-coupled glucose ...co-transporters (SGLTs) and facilitative Na
+
-independent sugar carriers (GLUTs), in the intestine. However, limited information has been available on these transporters in fish. Therefore, we studied
glut2
,
sglt1
, and
sglt4
genes in grass carp (
Ctenopharyngodon idellus
). The full-length cDNAs of
glut2
was 2308 bp, with an open reading frame (ORF) of 503 amino acids (AAs). The full-length cDNAs of
sglt1
was 2890 bp, with an ORF of 658 AAs. Additionally, the full-length cDNAs of
sglt4
was 2090 bp, with an ORF encoding 659 AAs. The three deduced AA sequences showed high homology between grass carp and other cyprinid fish species. Based on homology modeling, three-dimensional models of GLUT2, SGLT1, and SGLT4 proteins were created and transmembrane domains were noted.
glut2
,
sglt1
, and
sglt4
were abundantly expressed in the anterior and mid intestine. In particular,
glut2
was markedly expressed in liver (
P
< 0.05). Additionally, the results indicated that different stocking densities (0.9 or 5.9 kg m
−2
) did not alter intestinal section-dependent expression patterns of the three transporter genes. However, high stocking density impacted segmental mRNA expression levels. This work demonstrated that mRNA expression of sugar transporter genes in the fish intestine was segment specific, and crowding stress may affect the activity of intestinal sugar transporters. These results provided new insights into the relationship between crowding stress and intestinal sugar transporters in fish.
Cadmium (Cd) is a toxic pollutant in industrial production that induces organ damage and apoptosis, While, selenium (Se) has the biological function of antagonizing Cd toxicity. Hence, to gain ...further insight into the protective mechanisms of selenium against Cd-induced damage in Ctenopharyngodon idella liver (L8824) cells, L8824 were exposed to 5 μM, 15 μM, 25 μM cadmium chloride for 24 h after pre-incubation with 25 μM sodium selenite for 9 h. Cell proliferation and morphological changes, the levels of reactive oxygen species (ROS) and antioxidant enzyme activity, mitochondrial membrane potential (MMP), endoplasmic reticulum stress (ERS)-related pathway genes expression, intracellular calcium levels and apoptosis were assessed to explore the protective effect of selenium in Cd-induced L8824 cell damage. The results showed that Cd caused decreased cell viability, ROS accumulation, reduced activity of antioxidant enzymes (SOD, CAT GPx and T-AOC) and apoptosis in L8824 cells. The incubation of Se prominently ameliorated cell proliferation, activated the Keap1-Nrf2 pathway, and restored antioxidant enzyme activity. Furthermore, the expression of grp78, perk, eif-2α, atf4, chop bax, jnk, caspase-3 and caspase-9 was significantly upregulated after Cd exposure, while the expression of bcl-2 was significantly downregulated. Se supplementation alleviated Cd-induced ERS and apoptosis. Moreover, Cd-induced elevation of intracellular Ca2+ levels were alleviated by dantrolene and 2-APB, suggesting that intracellular calcium disorders were caused by Ca2+ released by RyR and IP3R-mediated ER. The results of this study suggested that Cd could induce oxidative stress, ERS, mitochondrial damage and evoke apoptosis, whereas Se had protective effects in preventing Cd induced damage by inhibiting ERS, maintaining intracellular calcium homeostasis, enhancing the antioxidant capacity of L8824 cells and downregulating the Keap1/Nrf2 pathway.
•Selenium alleviates endoplasmic reticulum stress and intracellular calcium disorders caused by cadmium exposure.•Selenium reduces oxidative damage caused by cadmium exposure by activating the NRF2-Keap1 signaling pathway.•Selenium reduces L8824 cell proliferation inhibition and apoptosis caused by cadmium exposure.
An experimental recirculating aquaculture system was constructed under ambient seawater conditions to compare microbial community diversity of nitrifying and denitrifying biofilters that were derived ...from a commercial inoculum used for aquarium applications. Next generation sequencing revealed distinct and diverse microbial communities in samples analyzed from the commercial inoculant and the denitrification and nitrification biofilters. In all samples, communities were represented by a few dominant operational taxonomic units (OTUs). Bacteria having the capacity to carry out ammonia and nitrite oxidation were more abundant in the nitrification biofilter. Similarly, the proportion of the bacterial taxa known to carry out heterotrophic and autotrophic denitrification and participate in sulfur cycling were found in the denitrification bioreactor, and likely originated from the ambient environmental water source. Our results indicated that environmental seawater can be a favorable enhancement to the bacterial consortium of recirculating aquaculture systems biofilters.
•Next generation sequencing was performed on populations in a recirculating aquaculture system.•Microbial communities established on biofilters were compared to commercial inoculum.•Environmental seawater used for filling the RAS provided additional bacteria.
In the area of the Neretva delta in the eastern Adriatic, where the European eel, Anguilla anguilla (Linnaeus, 1758) has been traditionally fished for centuries, a decline in its population has been ...observed, as in most of Europe. Despite several studies, systematic monitoring was not performed, and the causes of population decline are attributed to anthropogenic stressors, mainly overfishing and interventions that disrupt the migration. With the stock at a low level, there is a need for a detailed assessment of biological data and the determination of the “zero state” of the eel population in the areas where monitoring was not previously performed, such as the Neretva delta. This data would serve as a basis for the development of an appropriate monitoring and eel management plan. One of the under-researched aspects is still the eel’s morphology, which is closely related to all basic life functions. The aim of this work was to analyze in detail the morphological parameters of yellow and silver eels from the mouth of the Neretva River in different seasons and the relationships between the measured morphometric parameters and physiological indicators and to compare them with previously published results for different life stages across Europe. The samples were collected during spring, summer and autumn of 2021, and winter of 2022. Yellow eels were present in the catch throughout the sampling period, while silver eels were caught in the autumn and winter. Yellow and silver eels were significantly different regarding 22 morphometric measures that were analyzed. Isometric growth was recorded for yellow eels in the spring and autumn of 2021, and positive allometric growth was recorded for yellow eels in the summer and silver eels in the autumn of 2021 and winter of 2022. PCA showed that the main factor that separates the eels grouped by life stage in different seasons is the intestine length (IL), whereas the rest of the factors (weight—W; intestine weight—IW; liver weight—LW; and total length—TL) affect the groupings almost equally. Seasonal averages of the condition factor (CF) for yellow and silver eels did not differ statistically. Three indicators were used to describe intestine morphology: relative gut weight (RGW), relative gut length (RGL), and Zihler’s index (ZHI); and the only statistically significant difference between yellow and silver eels was recorded for the RGW. The hepatosomatic index (HSI) was significantly different between silver eels in winter and yellow eels in spring. In addition to supplementing the already known facts, this paper provides new information on the functional morphology of the European eel. Monitoring of these characteristics is crucial for management of the European eel fisheries as they are directly related to functional performance and affect the ability to maintain sustainable populations in anthropogenically altered environments.
Mediterranean Sea is the sixth largest area of marine litter accumulation in the world, and plastic pollution is a growing problem in its Adriatic sub-basin. The aim of the present study was to ...evaluate the cultivable microbiota associated with plastic litter collected by commercial fishing trawlers in the south-eastern Adriatic Sea in comparison with microbiota in seawater and sediment. Plastic litter in the sea contains an autochthonous microbiota that is different from that of the surrounding seawater and sediment. Vibrio abundance was higher on plastic litter than in surrounding seawater and sediment. All isolated Vibrio showing resistance to ampicillin and vancomycin, while resistance to other antibiotics depended on the isolated species. Overall, this study provides for the first time information on the cultivable microbiota associated with plastic litter collected by commercial fishing trawlers and provides a data base for further studies.
•Plastic litter collected by commercial fishing trawlers was analyzed.•The microbiota on plastic litter, in seawater, and in sediment was determined.•Vibrio parahaemolyticus and Vibrio alginolyticus were detected on plastic litter.•Multiple resistance among Vibrio isolates was detected.
The rapid development and intensive production of aquaculture have brought to light various environmental problems. In particular, fish farming adversely affects the benthic environments through the ...accumulation of organic matter (OM), which leads to the degradation of aquatic sediments and associated biotic communities. To prevent environmental degradation, proper site selection for fish farming is a prerequisite for sustainable aquaculture practices. An important physical factor in selecting a site for fish farming is sediment structure. Coarser sediments are preferred, while their mineral composition is rarely discussed. To investigate relationships between sediment characteristics and the content of OM, sediments were collected from three different sites with different aquaculture practices under different climatic and environmental conditions and analyzed during the one-year monitoring period. Grain size distribution, mineral composition, carbonate content, and organic matter content were determined for three fish farm sites (Ilova, River, Krka River, and Pelješac) and their reference sites. Preliminary results from all studied sites showed that sediment texture in combination with natural mineral composition is one of the key factors for the accumulation of OM in the sediment. In particular, the mineral composition of the fine-grained sediment should be known when conducting an environmental impact assessment of fish farms.
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