Enhancement of growth, antioxidative status, nonspecific immunity, and disease resistance in gibel carp (Carassius auratus) in response to dietary Flos populi extract

This study investigated the effects of dietary Flos populi extract (FPE) on the growth, antioxidation capability, innate immune response, and disease resistance in gibel carp. A total of 480 fish were fed with five different diets containing 0, 0.5, 1.0, 1.5, or 2.0 g kg−1 FPE (designated as control, D0.5, D1.0, D1.5, or D2.0 groups) for 45 days. The fish were challenged with A. hydrophila after the feeding trial. Compared with the control, the feed efficiency (FE), weight gain (WG), final body weight (FBW), and specific growth rate (SGR) were significantly improved in groups D1.0 and D1.5. Dietary FPE significantly increased serum superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities, as well as glutathione (GSH) content. The contents of protein carbonyl (PCC) and malondialdehyde (MDA) in serum decreased significantly. Additionally, FPE supplementation in diets resulted in significant improvement in serum lysozyme (LZM) and myeloperoxidase (MPO) activities, as well as immunoglobulin M (IgM) and complement 3 (C3) concentrations. The hepatic antioxidant enzymes (CAT and SOD) activities increased, whereas content of MDA decreased in fish treated with dietary FPE than those of control both pre- and post-challenged. After 12 h-challenge, an obvious downregulation of hepatic Kelch-like-ECH-associated protein 1 (Keap1), splenic tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-1β, and toll-like receptor 2 (TLR2) mRNA levels was observed in fish treated with dietary FPE, whereas hepatic Nrf2 transcription level was upregulated compared to the control. Furthermore, compared to group D0.5, higher relative percent survival (RPS) was observed in gibel carp fed dietary 1.0–2.0 g/kg FPE. Our results reveal that FPE supplemented diet has a stimulatory effect on antioxidant capacity and nonspecific immune response, along with improved growth performance and enhanced resistance against A. hydrophila infection in juvenile gibel carp.

Mitochondrial sequence diversity reveals the hybrid origin of invasive gibel carp (Carassius gibelio) populations in Hungary

Background Invasive gibel carp, Carassius gibelio (Bloch, 1782) has become well-established in the Hungarian waters and now are spreading in the European waters. On major concern now is the potential hybridization between gibel carp and the other invasive species in the Carassius auratus complex (CAC), which may further accelerate the spread of the whole invasive species complex. The identification of gibel carp and their hybrids is difficult because of its morphological similarity to the other species in CAC. Here we carry out a genomic assessment to understand the history of gibel carp invasion and its phylogenetic relationship with the other species in CAC. Three loci of the mitochondrial genome (D-loop, CoI, Cytb) were used to determine the phylogenetic origin of individuals and relarionship among six gibel carp populations and the other species in the CAC. Methodolgy A total of 132 gibel carp samples from six locations in Southern Transdanubia (Hungary) were collected after phenotypic identification to measure the genetic diversity within and among gibel carp populations of Southern Transdanubia (Hungary). The genetic background was examined by the sequences of the mitochondrial genome: D-loop, Cytochrome c oxidase I (CoI) and Cytochrome b (Cytb). Mitochondrial genetic markers are excellent tools for phylogenetic studies because they are maternally inherited. Successfully identified haplotypes were aligned and with reference sequences in nucleotide databases (i.e., NCBI-BLAST: National Centre for Biotechnology Information and BOLD: Barcode of Life Data System). The phylogenetic relationships among gibel carp populations were then analyzed together with the reference sequences to understand the relationship and the level of hybridization with the species in CAC. Results Among the 132 aligned D-loop sequences 22 haplotypes were identified. Further examination of representative individuals of the 22 haplotypes, six Cytb and four CoI sequences were detected. The largest number of haplotypes of all three loci were found in Lake Balaton, the largest shallow lake in Central Europe. Based on the NCBI-BLAST alignment of the D-loop, haplotypes of Carassius auratus auratus and Carassius a. buergeri in CAC were identified in the C. gibelio samples. Further analysis of haplotypes with the other two mitochondrial markers confirmed the occurrence of intragenus hybridization of C. gibelio in the Hungarian waters. Conclusion By using three mitochondrial markers (D-loop, Cytb, CoI), we genomically characterized a gibel carp-complex in Hungarian waters and assessed the C. gibelio phylogenetic status between them. Hybrid origin of locally invasive Carassius taxon was detected in Hungary. It points out that invasive species are not only present in Hungary but reproduce with each other in the waters, further accelerating their spread.

Monitoring of the ecological state of the city lake of Chita

Introduction. The paper presents the results of the studies on assessing the quality of the aquatic ecosystem of a lake located within the city. The European perch (Perca fluviatilis L.) and the Gibel carp (Carassius gibelio) were used as an indicator for determining the quality of the aquatic ecosystem by the method of fluctuating asymmetry. Problem Statement. The aim of the work was to conduct monitoring with the subsequent assessment of the quality of the ecosystem of the city lake using the method of fluctuating asymmetry (hereinafter FA). Theoretical and Practical Part. The quality of the urban lake aquatic ecosystem was assessed using the FA method (indicators: the European perch (Perca fluviatilis L.), 1758 and the Gibel carp (Carassius auratus Bloch), 1783). To identify the reasons for the high PFA values, a chemical analysis (in an accredited laboratory) of the gills of the Gibel carp for heavy metals was performed. Conclusions. As a result of the research, the FA indicators values for these indicators were obtained. According to the results of a laboratory study of the content of heavy metals in the gill arches of the Gibel carp, an excess of the maximum permissible concentration of 8 out of 10 analyzed elements was revealed. It has been established that the ecosystem of the city lake Kenon is experiencing a significant anthropogenic load (5 points — the critical quality of the aquatic environment) and it continues to increase towards the deterioration of the habitat.

Two Duplicated Ptpn6 Homeologs Cooperatively and Negatively Regulate RLR-Mediated IFN Response in Hexaploid Gibel Carp

Src homology region 2 domain-containing phosphatase 1 (SHP1), encoded by the protein tyrosine phosphatase nonreceptor type 6 (ptpn6) gene, belongs to the family of protein tyrosine phosphatases (PTPs) and participates in multiple signaling pathways of immune cells. However, the mechanism of SHP1 in regulating fish immunity is largely unknown. In this study, we first identified two gibel carp (Carassius gibelio) ptpn6 homeologs (Cgptpn6-A and Cgptpn6-B), each of which had three alleles with high identities. Then, relative to Cgptpn6-B, dominant expression in adult tissues and higher upregulated expression of Cgptpn6-A induced by polyinosinic-polycytidylic acid (poly I:C), poly deoxyadenylic-deoxythymidylic (dA:dT) acid and spring viremia of carp virus (SVCV) were uncovered. Finally, we demonstrated that CgSHP1-A (encoded by the Cgptpn6-A gene) and CgSHP1-B (encoded by the Cgptpn6-B gene) act as negative regulators of the RIG-I-like receptor (RLR)-mediated interferon (IFN) response via two mechanisms: the inhibition of CaTBK1-induced phosphorylation of CaMITA shared by CgSHP1-A and CgSHP1-B, and the autophagic degradation of CaMITA exclusively by CgSHP1-A. Meanwhile, the data support that CgSHP1-A and CgSHP1-B have sub-functionalized and that CgSHP1-A overwhelmingly dominates CgSHP1-B in the process of RLR-mediated IFN response. The current study not only sheds light on the regulative mechanism of SHP1 in fish immunity, but also provides a typical case of duplicated gene evolutionary fates.

Using binders for feed producing needed for aquaculture

The article is dedicated to binders, which are used as components of aquaculture feeds. It includes generalization results of modern scientific-applied stuff, mostly obtained by foreign researches, since this kind of information presented at domestic specialized journals in extremely small volume. An information about functional purpose for main feed components — protein- and oil-containing, antioxidants and some others — was presented. Binders impaction on aquatic feed attraction and it’s nutritional value was shown, general functional purposes for binding agents also explained. A small analytical description for Russian binder market presented, a modern classification for binders also was shown as well as main segments in feed market where these binders can be used. Differences in rheological characteristics of various binders and it’s interaction mechanism with feed components within granules are described. Significant differences between Russian and foreign methodologies, used for researching of structurally-mechanical characteristics of feed pellets, are indicated and needs in domestic and foreign analytical techniques harmonization was justified. This article includes results of foreign investigations, dedicated of binders applied using (such as starches, obtained from various raw sources, carrageenan, CMC, pectin, agar, gelatin and so on) while pelleted and extruded feeds production was summarized. Crayfishes, shrimps, sea urchins and fishes (gibel carp, olive flounder) were used for researching and were fed by feeds with these binders. The best kinds of binders and it’s most effective concentrations for feeds, used for various species was defined, impaction on fish farming efficiency also was studied for some of these binders. Needs for further researching works with binders for using in feed production industry was justified. English version of the article is available at URL: https://panor.ru/articles/use-of-binding-substances-in-the-production-of-mixed-feeds-for-aquaculture/74633.html

Non-invasive ploidy determination in live fish by measuring erythrocyte size in capillaries

Information about ploidy is important in both commercial and conservation aquaculture and fish research. Unfortunately, methods for its determination, such as karyology, determination of the amount of DNA in a cell using microdensitometry or flow cytometry and/or measuring erythrocytes in a blood smear can be stressful or even destructive. Some of these methods are also limited by the relatively large minimum size of the individual being measured. The aim of this study was to test a new low-stress method of determining ploidy by measuring the size of erythrocytes in the capillaries of a fish, including small individuals. First, we examined diploid and triploid loach (Cobitis sp.) and gibel carp, Carassius gibelio (Bloch, 1782), using flow cytometry and blood smears, with these results being used as a control. Subsequently, we measured the size of erythrocytes in the caudal fin capillaries of anesthetized fishes of known ploidy under a light microscope. For both the loaches and gibel carp, direct observation of the mean erythrocyte size in epithelial fin capillaries provided a consistent and reliable determination of ploidy when compared with the controls based on flow cytometry and blood smears. This new method allows for rapid determination of ploidy in living small fish, where collection of tissue using other methods may cause excessive stress or damage. The method outlined here simply requires the measurement of erythrocytes directly in the bloodstream of a live fish, thereby making it possible to determine ploidy without the need for blood sampling. The method described is sufficiently efficient, less demanding on equipment than many other procedures, can be used by relatively inexperienced personnel and has benefits as regards animal welfare, which is especially important for fish production facilities or when dealing with rare or endangered species.

Non-invasive ploidy determination in live fish by measuring erythrocyte size in capillaries

Information about ploidy is important in both commercial and conservation aquaculture and fish research. Unfortunately, methods for its determination, such as karyology, determination of the amount of DNA in a cell using microdensitometry or flow cytometry and/or measuring erythrocytes in a blood smear can be stressful or even destructive. Some of these methods are also limited by the relatively large minimum size of the individual being measured. The aim of this study was to test a new low-stress method of determining ploidy by measuring the size of erythrocytes in the capillaries of a fish, including small individuals. First, we examined diploid and triploid loach (Cobitis sp.) and gibel carp, Carassius gibelio (Bloch, 1782), using flow cytometry and blood smears, with these results being used as a control. Subsequently, we measured the size of erythrocytes in the caudal fin capillaries of anesthetized fishes of known ploidy under a light microscope. For both the loaches and gibel carp, direct observation of the mean erythrocyte size in epithelial fin capillaries provided a consistent and reliable determination of ploidy when compared with the controls based on flow cytometry and blood smears. This new method allows for rapid determination of ploidy in living small fish, where collection of tissue using other methods may cause excessive stress or damage. The method outlined here simply requires the measurement of erythrocytes directly in the bloodstream of a live fish, thereby making it possible to determine ploidy without the need for blood sampling. The method described is sufficiently efficient, less demanding on equipment than many other procedures, can be used by relatively inexperienced personnel and has benefits as regards animal welfare, which is especially important for fish production facilities or when dealing with rare or endangered species.