Comparative studies of codon usage profile of Anisakis simplex (Nematoda) and Carassius gibelio (Prussian carp)

Aim: The aim of the present study was to understand the molecular relationship between nematode (parasite) and fish (host) through codon usage bias (CUB) analysis. Methodology: The Codon usage bias analysis has been performed in fish Carassius gibelio (Prussian carp) and nematode fish parasite Anisakis simplex. The complete coding sequences (CDS) of C. gibelio (Prussian carp) and A. simplex (Nematode) were retrieved from National Center for Biotechnology Information and followed to that we have performed bioinformatics analysis to understand the codon usage pattern between host and parasite. Results: Different CUB indices like Relative synonymous codon usage (RSCU), Effective number of codons (ENC), Codon adaptation index (CAI) and Codon bias index (CBI) revealed a similar pattern in the codon usage in C. gibelio and A. simplex. In addition, inclusive analysis using different plots (ENC, parity, neutrality) had shown the influence of both the evolutionary forces i.e mutational and translational selection on codon usage pattern. This describes the role of evolutionary forces in determining the conserved genome to establish species-specific function-level differences for efficient survival. Interpretation: The present study elucidated the association between Carassiusgibelio (host) and Anisakis simplex (parasite) based on the similar pattern of codon usage bias between both the species.

Helminths and helminth communities of Carassius gibelio (Bloch, 1782) from the Panicheri Reservoir, Aegean Water Basin, Bulgaria

Ecologoparasitological research was done based on the helminths and helminth communities of the Prussian carp (Carassius gibelio (Bloch, 1782)) from the freshwater ecosystem of the Panicheri Reservoir, Aegean Water Basin, Bulgaria. As a result of the examined nine specimens of the Prussian carp, two species of helminths were found: Ligula intestinalis (Linnaeus, 1758), larvae and Pomphorhynchus laevis (Müller, 1776). The dominant structure of the helminth communities was determined. The Panicheri Reservoir is a new habitat in Bulgaria of P. laevis and L. intestinalis from C. gibelio. C. gibelio is a new host record for L. intestinalis in Bulgaria. The two helminth species are core species for the helminth communities of the examined species of the freshwater fish. P. laevis was distinguished with higher prevalence and mean intensity (P%=33.34; MI=1.34) than L. intestinalis (P%=22.23; MI=1.0). The circulatory pathways of the helminth flow were traced.

Potentially Toxic Elements in Invasive Fish Species Prussian Carp (Carassius Gibelio) from Different Freshwater Ecosystems and Human Exposure Assessment

Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, and Zn were detected in the muscle and gills of Prussian carp from three different freshwater ecosystems: isolated ponds and the South Morava River in Serbia, and Kopačko Lake in complex wetland ecosystem of the Kopački Rit Nature Reserve in Croatia. The main goals of the paper were to assess the concentrations of potentially toxic elements (PTEs) in the muscle and gills of Prussian carp (Carassius gibelio), to examine whether abiotic factors from three different freshwater ecosystems affect the accumulation of PTEs in fish tissues and to estimate the human health risk resulting from fish consumption. There were only six concentrations of PTEs in the gill tissue (Cr, Hg, Mn, Pb, Sn, and Zn) that were not significantly different among the different freshwater ecosystems. In the muscles, the differences were much less visible. Kopačko Lake distinguished with the highest values of metal pollution index (MPI) for muscles (0.24) and isolated ponds with the highest values of MPI for gills (0.8). The redundancy analysis (RDA) showed that concentrations of Al, Mn, Zn, Cu, and Fe in the gill tissue were significantly correlated with the environmental variables. In contrast, the RDA based on element concentrations in the fish muscles indicated no significant relationship with the environment. Isolated ponds, with no inflow of freshwater, stand out as the most polluted, followed by Kopačko Lake with occasional floods. Flowing freshwater ecosystem South Morava River can be single out as at least polluted with PTEs. The target hazard quotients (THQ) and hazard index (HI) suggested there were no significant noncarcinogenic health risks. The target carcinogenic risk factor (TR) for As and Pb confirmed there were no cancer risks related to human fish consumption. Since the elevated concentrations of toxic Cd and As in Prussian carp were estimated, an early warning should be assumed, especially for fishing activities in these areas.

The structure of fish communities in Bistrita River, upstream the confluence with Siret River (Romania)

The researches were carried out in 2020 on the main course of Bistrița River, upstream the confluence with Siret River. The biological material was sampled in 10 sampling sites placed on the main course of Bistrița River. Seventeen fish species were identified, one of them being a non-native one: Pseudorasbora parva. We found that the chub and the Prussian carp are characteristic species. Species diversity is quite high, being identified even 12 fish species in some of the sampling sites. There is an unequal distribution of individuals by species. The main threats in the research area are the organic inputs and the increase of turbidity. However, there are no great imbalances, and there is a good capacity for self-support of aquatic communities.

Cadmium Accumulation and Depuration in the Muscle of Prussian Carp (Carassius gibelio Bloch) after Sub-Chronic Cadmium Exposure: Ameliorating Effect of Melatonin

The aim of this study was to investigate the bioaccumulation of cadmium in the muscle tissue of Prussian carp during 7 and 13 weeks of exposure to different concentrations of this metal in water (0.4 and 4.0 mg/L), and the depuration of cadmium from muscle during the following 6-week depuration period in the presence of melatonin implants. Furthermore, the relationship between cadmium accumulation and the levels of essential bioelements (copper, zinc, iron) in muscle was evaluated, as well as the bioconcentration factor of cadmium. Heavy metal concentration was determined using atomic absorption spectrometry. Cadmium accumulation in fish muscle increased with the duration of exposure. Cd concentrations exceeded the permissible levels for human consumption in groups exposed to the higher concentration of this metal. Moreover, a significant increase of Zn and Fe levels in the muscle was observed. In the fish that received melatonin implants and were exposed to Cd, its level in the muscle was significantly lower. The depuration of accumulated cadmium depended mainly on the duration of the elimination period. This is the first study to report that melatonin co-administration can effectively protect the fish from the accumulation of cadmium in muscle tissue and changes in trace metal levels.

Advancing improvement in riverine water quality caused a non-native fish species invasion and native fish fauna recovery

The knowledge of biotic and abiotic drivers that put non-native invasive fishes at a disadvantage to native ones is necessary for suppressing invasions, but the knowledge is scarce, particularly when abiotic changes are fast. In this study, we increased this knowledge by an analysis of the biomass of most harmful Prussian carp Carassius gibelio in a river reviving from biological degradation. The species' invasion followed by the invasion's reversal occurred over only two decades and were documented by frequent monitoring of fish biomass and water quality. An initial moderate improvement in water quality was an environmental filter that enabled Prussian carp’s invasion but prevented the expansion of other species. A later substantial improvement stimulated native species’ colonization of the river, and made one rheophil, ide Leuciscus idus, a significant Prussian carp’s replacer. The redundancy analysis (RDA) of the dependence of changes in the biomass of fish species on water quality factors indicated that Prussian carp and ide responded in a significantly opposite way to changes in water quality in the river over the study period. However, the dependence of Prussian carp biomass on ide biomass, as indicated by regression analysis and analysis of species traits, suggests that the ecomorphological similarity of both species might have produced interference competition that contributed to Prussian carp’s decline.

Cadmium Accumulation in the Scales of Prussian Carp (Carassius Gibelio Bloch, 1782) Following Exposure to Cadmium in Water

The aim of the study was to investigate the accumulation of cadmium in the scales of Prussian carp (Carassius gibelio Bloch, 1782) as an indicator tissue of water contamination by cadmium. The study was carried out on 130 mature Prussian carp, which were placed in three 300L tanks. The fish were exposed to cadmium dissolved in water at a concentration of 0.0, 0.4 or 4.0 mg/L for a period of 84 days. After 42 and 84 days of exposure, 10 fish were randomly sampled from each tank. The fish were decapitated and all their scales were collected. The scales were rinsed and each of them was then carefully sectioned into an inner part and an outer part, removing the outermost growth ring, which most likely included scale increment from the exposure period. Cadmium concentration in the samples was then measured using the atomic absorption method. The analysis of the results showed that the concentration of cadmium in the scales increased with the duration of exposure and was significantly higher in the outer growth rings. The accumulation of cadmium in this part of the scales was correlated with the dose of cadmium and the duration of exposure. The results obtained confirmed the hypothesis that the concentration of cadmium in the outermost growth rings of fish scales reflects the most recent status of environmental contamination by this metal. Scales, which unlike other tissues such as the liver and muscle, can be sampled non-lethally, seem to be an excellent bioindicator of environmental contamination by heavy metals.

ГІСТОЛОГІЧНА ХАРАКТЕРИСТИКА ЗЯБЕР ТА НИРОК КАРАСЯ СРІБЛЯСТОГО З ЗАПОРІЗЬКОГО (ДНІПРОВСЬКОГО) ВОДОСХОВИЩА

In this article the histological structure of gills and kidneys of the Prussian carp is considered and researched. The research was conducted in the waters of the Zaporizhian (Dnipro) reservoir, namely in the Samara Bay and the lower part of the reservoir (near the village of Viiskove) during 2017–2019. Previous studies have revealed the excess of maximum permissible concentrations of heavy metals in the water of the Samara Bay compared to the lower part of the Zaporozhian reservoir. High levels of nickel and cadmium were observed in the Samara Bay. Statistically significant differences were found between the content of copper, zinc, nickel, lead and cadmium in the two areas of the reservoir (p