Volume 75, Issue 2, 2023

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https://hdl.handle.net/10524/70422

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Effect of ginger, Zingiber officinale extract on growth performance, digestive enzyme and stress tolerance of whiteleg shrimp, Litopenaeus vannamei juveniles
(2023) Tu, Phan Thi Cam; Lien, Nguyen Thi Kim; Diep, Doan Xuan; Ly, Tien Hai
This study evaluated the effects of ginger extract as a feed additive on the growth performance, digestive enzymes, and resistance to environmental stress of the whiteleg shrimp, *Litopenaeus vannamei*. 1200 juveniles were randomly allocated into four groups with three replicates. Shrimps were fed diets supplemented with 0 (T0-control), 0.5 (T1), 1 (T2), and 1.5 g kg^-1^ of ginger extract (T3) for 56 days. The results indicated that shrimp fed with ginger extract had a lower feed conversion ratio (FCR) than the control. In addition, shrimp fed with 0.5 g kg^-1^ of ginger extract had significantly greater weight gain and protease activity in the intestine than those in the control group. However, dietary supplementation with ginger extract did not significantly affect survival rates. After 56 days of culture, shrimp fed with 0.5 and 1 g kg^-1^ of ginger extract had higher survival rates than the controls after 72 -- 96 h exposure to high ammonia stress (40 mg L^-1^). Based on the study's findings, ginger extract could be recommended for shrimp feed to enhance growth and resistance against stress factors, and the optimal level is 0.5 g kg^-1^.
Population genetics analysis of the black rockfish Sebastes schlegelii in Northern China based on 2b-RAD simplified genome sequencing
(2023) Cao, Wei; Zhang, Mingyi; Wu, Nan; Han, Haiying; Zhong, Rujie; Yu, Tao; Wang, Xiaomei; Ren, Liqun; Zhao, Chunnuan; Li, Bo; Zheng, Yanxin
The black rockfish Sebastes schlegelii is an important fishery species in Japan, South Korea, and China. Overfishing has severely depleted the natural resources of S. schlegelii in recent years, leading to the initiation of programs aimed at enhancing fish stock. However, the genetic structure of northern populations remains elusive, posing challenges in collecting and preserving germplasm resources. In this study, a total of 191 S. schlegelii individuals from seven populations, including one cultured population (Changdao: CDYZ) and six wild populations (Lianyungang: LYG; Qingdao: QD; Weihai: WH; Changdao: CDYS; Beidaihe: BDH) sequenced by 2b-RAD method and their population genetics was analyzed using 27,064 SNPs obtained. The results indicated low genetic diversity in both wild and cultured populations (PIC < 0.25, Ho: 0.174-0.273, He: 0.173-0.234), with the cultured population exhibiting higher diversity than the wild ones. Moderate genetic differentiation existed between the cultured population and six wild populations (0.05 < Fst < 0.25). However, the genetic differentiation was lower among the other wild populations (Fst < 0.05). The analyses of population genetic structure indicated that the wild populations clustered together first and finally with the cultured population CDYZ, which clustered separately except for one individual. Therefore, scientific breeding programs and germplasm conservation can be important in stabilizing genetic structure. In addition, gene flow among the seven populations was high (Nm > 1). This study provides a theoretical basis for conserving and rationalizing germplasm resources for S. schlegelii.
Determination of Growth and Nutritional Composition of Nile Tilapia (Oreochromis niloticus) Fed With L-Glutamic Acid Supplemented Feeds
(2023) Dağdelen, Yılmaz; Taşbozan, Oğuz
The study aimed to assess Nile tilapia's (Oreochromis niloticus) growth performance and body chemical composition through varying levels of L-Glutamic acid supplementation. In the experiment, four different groups of feed were prepared; the control C (0% L-Glutamic acid), G1 (1% L-Glutamic acid), G2 (2% L-Glutamic acid), and G3 (3% L-Glutamic acid). Tilapia juveniles with an average initial weight of 4.86 g were stocked into 12 fiberglass tanks (450L) with 40 individuals and three replications under controlled conditions, and the experiment was continued for a period of 60 days. At the end of the experiment, for the G2 group final weight (FW, 19.31±0.59 g), specific growth rate (SGR; 2.30±0.05), feed conversion ratio (FCR; 1.02±0.03), daily growth rate (DGR; 4.95±0.20) protein efficiency ratio (PER 2.83±0.10) and net protein utilization (NPU; 61.62±3.39) were better than the other groups (P<0.05). Nutritional composition data showed that the groups differed between protein, dry matter, and lipid compositions. The G2 group exhibited the highest whole-body protein level, recording a value of 21.24±0.52, whereas the control group demonstrated the lowest protein level at 20.17±0.15. In conclusion, incorporating 2% L-Glutamic acid into the diet of juvenile Nile tilapia is advisable for both the growth and development of the fish and for enhancing their nutritional composition.
Comparative analysis of Streptococcus agalactiae S03 and S07 isolated from Schizothorax spp. with different antibiotic resistance and virulence
(2023) Wang, Yihao; Yuan, Yu; Peng, Kun; Wang, Yilin; Deng, Longjun; Li, Tiancai; Chen, Defang; Ouyang, Ping; Huang, Xiaoli; Guo, Hongrui; Deng, Huidan; Lai, Weiming; Geng, Yi
Streptococcus agalactiae (GBS) is an important Gram-positive pathogen of ﬁsh aquaculture worldwide. In this study, we performed a comparative analysis of GBS S03 (serotype III) and S07 (serotype Ia) isolated from Schizothorax spp.. We explored the association between phenotypic antibiotic resistance, virulence, and genomic characteristics. Antimicrobial sensitivity tests on 12 common antibiotics using the disc diffusion method revealed that the GBS S03 resisted seven antibiotics, while GBS S07 showed sensitivity to eleven antibiotics. Pathogenicity analysis demonstrated greater virulence of GBS S07 than S03. Then, the occurrence of antibiotic resistance and virulence genes were identified using the whole-genome sequence (WGS) of GBS S03 and GBS S07. Besides just GBS S03 had gyrA and parC gene mutations, there were mefE, tetO, lnuB, lsaE, APH3', and sat-4 resistance genes present only in GBS S03 genome. In addition to 51 virulence genes in both GBS S03 and S07 genomes, GBS S07 carried virulence genes associated with invasion, such as SAN1519, rfbA and cylE_ genes. There was complete concordance between genotypic evidence and phenotypic characteristics. Virulence factors and phylogenetic analysis showed that GBS S03 and human sources shared an extremely close evolutionary relationship. Our findings also provide important proof for using WGS as an effective tool for phenotypic predictions of GBS.
Effects of cadmium exposure on tissue structure, antioxidant enzyme activity, serum biochemical indices and gene expression in the liver of juvenile largemouth bass (Micropterus salmoides)
(2023) Liu, Hui; Pei, Zhuo; Fan, Ke; Liu, Yuanyi; Wang, Yang; Liu, Yumei; Huang, Yong
This study aimed to understand the effect of various levels of waterborne cadmium exposure and associated integrated response in largemouth bass (Micropterus salmoides). The experimental fish were randomly divided into 4 groups: Group H (high concentration group): 0.25 mg/L of water (100% of the LC~50~); Group M (medium concentration group): 0.01 mg/L of water (50% of the LC~50~); group L (low concentration group): 0.05 mg/L of water (12.5% of the LC~50~) and group C (control). Experimental fish in group C (control group) were cultured in cadmium (Cd)-free tap water. After 28 days of Cd exposure, the gill and liver tissues were collected for histological analysis and antioxidant enzyme activities assay. Serum biochemical indices and the expression levels of HSP70, HSP90, Cyp1a, and MT in the liver were assayed. Results indicated Cd exposure in group H could significantly damage the gill and liver. The SOD activity of gill and liver exhibited an increasing trend with Cd concentrations increasing, and SOD activities increased significantly in group M compared to that of group C. Still, SOD activity significantly decreased in group H. MDA content increased significantly in both the gill and liver, while T-AOC activities were not significantly different in both the gill and liver. By comparison with group C, the activities of ALT and AST in serum were significantly increased in group M and group H; the contents of ALB and TP significantly decreased in group M and group H except for the content slightly increased in the group L; the contents of GLU, TG, and TC did not show significant changes in the group L and the group M, but increased significantly in the group H. The expression levels of HSP70 and HSP90 in the liver exhibited the highest level in group M, whereas the expression levels of MT and Cyp1a were highest in groups H and L, respectively. Our results are intended to provide a reference basis for the safety risk evaluation of Cd and healthy fish farming.
Effects of Mn2+ and flow speed on blood and physiological indexes of larvae GIFT tilapia (Oreochromis niloticus)
(2023) Song, Bolan; Zhao, Luqi
To assess the toxicological effects of heavy metal ions on fish at different flowing speeds within aquatic environments, we investigated the impact of Mn^2+^ and flow speed on the physiological parameters of juvenile GIFT tilapia (95.2±4.3g,15.1±0.21cm). The experiment design included four different levels of Mn^2+^ concentration: control group (0mg/L), 0.1mg/L, 0.5mg/L and 1mg/L, as well as three different flow speeds: control group (0 body length/second), low speed (1 body length/second), and high-speed group (2 body lengths/second). The main research findings were as follows: Mn^2+^ had varying effects on the hematological parameters of juvenile GIFT tilapia. As the levels of Mn^2+^ increased, there was a remarkable reduction in both the red blood cell (RBC) number and hemoglobin content of the fish(*P*\<0.05). The activity of SOD, CAT, the level of MDA in the liver and white blood cell (WBC) number exhibited an initial increase followed by a subsequent decrease, with the highest levels observed mostly in the 0.5mg/L group. However, With the prolongation of Mn^2+^ exposure duration, a significant decline in levels of RBC, hemoglobin, CAT and SOD was observed. In most cases, the highest values of those, as mentioned earlier four physiological parameters were recorded at 24 hours, while the lowest values were recorded at 96 hours when exposed to the same Mn^2+^ level. However, MDA levels reached their peak at 48 hours. These findings suggested that lower levels of Mn^2+^ might enhance the immune capacity of tilapia, while higher levels could impede its immune and antioxidant functions. An increase in flow speed led to a significant elevation in both the RBC number and hemoglobin content of the GIFT tilapia at 30d(*P*\<0.05), but flow speed had no significant impact on the WBC of the fish(*P*\>0.05). Its effect on the fish antioxidant parameters also showed a certain induction, and there were significant correlations between the activity of SOD, CAT, the level of MDA, and flow speed (*P*\<0.05). At the same flow speed, the prolonging water-flow-stimulus duration could not increase the levels of three antioxidant parameters(*P*\>0.05). These findings could provide fundamental data for investigating the influence of heavy metal stress on fish ecotoxicology in aquatic environments and the artificial running water breeding of GIFT tilapia in Hebei province, China.
Comparison of live microalgae and Spray-dried algae powder effects on growth, digestive and antioxidant capacity of juvenile pearl oyster Pinctada maxima
(2023) Li, Yi; Vasquez, Hebert Ely; Yin, Ze; Chen, Yu; Mao, Jing; Wang, Lingfeng; Zhang, Meng; Lan, Shuaiqin; Wei, Shangkun; Yu, Feng; Zheng, Xing; Gu, Zhifeng
The pearl production through the pearl oyster *Pinctada maxima's* culture has developed slowly over the past decades due to over-fishing of wild populations and mass mortality at juvenile stages. Indoor farming is an alternative mode for *P. maxima* juvenile cultivation to improve survival rates. In pursuit of optimizing healthy management under the indoor farming mode, the objective of this investigation was to compare the growth performance, digestion, and antioxidant capacity of juveniles fed with different microalgae-based diets (live *Isochrysis zhanjiangensis,* *Platymonas subcordiformis*, *Chaetoceros muelleri*; and spray-dried *I. zhanjiangensis*, *P. subcordiformis*, *C. muelleri* powder). The juvenile survival rates fed with spray-dried microalgae powder (except *C. muelleri* powder) were not significantly different from those fed on live microalgae. However, the growth performance of juveniles fed with spray-dried microalgae powder could have been better than the live one. The digestive enzymatic activities were consistent with growth performance, and diets affected the antioxidant capacity. The spray-dried *I. zhanjiangensis* powder can serve as a substitute for live microalga in *P. maxima* juvenile indoor farming and is recommended under controlled conditions. The findings from this study would provide essential data to improve health management for *P. maxima* juveniles in indoor farming conditions.
Transcriptome Analysis of the Cultured Hybrid Grouper (♀*Epinephelus fuscoguttatus*×♂*E. lanceolatus*) Immunized with Vibrio harveyi formalin-killed cells vaccine (FKC) combined with chitosan oligosaccharide
(2023) Wan, Xiaoju; Da, Fan; Lin, Guixiang; Huang, Yucong; Cai, Shuanghu; Jian, Jichang
Grouper has become an essential mariculture species in China, while vibriosis caused by Vibrio harveyi significantly impacts its culture. Our previous study confirmed the *V. harveyi* formalin-killed cells vaccine (FKC) combined with chitosan oligosaccharide (FKC+COS) effectively prevents vibriosis. As an adjuvant, COS could significantly enhance FKC effectiveness against *V. harveyi* in grouper. In the present study, we performed transcriptome analysis of grouper spleens tissue 14 days post-immunization of PBS and FKC+COS, respectively. After assembly and annotation, 2,503 differentially expressed genes (DEGs) were obtained, including the upregulated 1,894 DEGs and downregulated 609 DEGs between the PBS group and FKC+COS group. To explore the relevance of DEGs in immunity, enrichment analysis in the KEGG database revealed that the main pathways of DEGs distribution associated with immunity were antigen processing and presentation, lysosome, the intestinal immune network for IgA production and FcγR-mediated phagocytosis. In conclusion, transcriptome analysis of spleens was performed to explore the potential mechanism of COS as an adjuvant enhancing the protection effectiveness of FKC against vibriosis in grouper.
Effects of replacing dietary fishmeal with zymolytic black soldier fly larvae on the growth performance of the mud crab (scylla paramamosain) larvae
(2023) Yang, Qibin; Fan, Rui; Ma, Zhenhua; Jiang, Song; Huang, Jianhua; Yang, Lishi; Li, YunDong; Yang, Rui; Hu, Jing; Zhou, Shengjie; Su, Qiong; Zhou, Fa-Lin
Black soldier fly have been shown to be one of the optimal alternatives to fishmeal, but there are few reports on the effects of zymolytic black soldier fly larvae (ZBSFL) on the growth and digestion of crustaceans. An 8-week feeding trial was conducted to evaluate the effects of different replacement levels of ZBFLS on growth performance, body composition, and digestive enzyme activity of the mud crab larvae. Four diets were formulated by replacing fishmeal with 0%, 5%, 10% and 15% ZBSFL in the basal diet. Crab larvae were randomly divided into four groups of three replicates each and fed twice daily. The results showed that the SR of crab larvae was higher than that of the no-substitution group when the substitution rate reached 5% (P < 0.05). There was no significant change in SR when the substitution rate was further increased. Weight growth rate and Specific growth rate were similar, both highest at 10% substitution ratio. The crude protein content of whole crab larvae gradually increased as the proportion of FM substituted by ZBSFL increased. The lipid content of whole crab larvae in the 5% substitution ratio group was significantly higher than that in all other groups (P < 0.05). Meanwhile. The activities of amylase, protease and lipase gradually increased. In this experiment, when the percentage of ZBSFL substitution for FM reached 10%, its growth performance was optimal, with higher SR, less negative effects and more balanced indicators in all aspects. When the substitution rate was further increased, it might increase the digestive burden of the crab and negatively affect its growth.
Using black soldier fly larvae as feed for Thai frog (Rana rugosa Temminck and Schlegel, 1838) – Preliminary study of the effect on production parameters
(2023) Nghia, Vo D.; Lan, Pham T.P.; Tram, Nguyen D.Q.
This study aimed to evaluate the effect of the inclusion of either fresh or dried black soldier fly larvae (BSFL) in diets on the production parameters and chemical composition of Thai frogs (Rana rugosa) cultured in net cages. Frog fingerlings have an initial weight of 20.4 g and were distributed randomly into fifteen net cages (2 x 3 x 1.5 m) at a density of 240 frog.net cage-1. Including five dietary treatments named: T1 (100% commercial feed used as a control), T2 (100% dried BSFL), T3 (50% dried BSFL + 50% commercial feed), T4 (50% fresh BSFL + 50% commercial feed), and T5 (100% fresh BSFL) with three replicates for each treatment. The results showed that the survival rate of frogs ranged from 64.3% to 87.0%, improved feed conversion ratio (1.43 to 1.90%), increased live weight (194.7 – 244.6 g), daily weight gain (2.9 – 3.7 g.day-1), and frog’s yield (6.30 – 7.96 kg.m-2). The contents of crude protein (18.21 – 23.19%), ether extract (0.28 – 0.53%), and total ash (0.99 – 1.05%) of frog meat in this study were affected by the inclusion of either fresh or dried BSFL in the diets of frogs. In recommendation, the diet comprised from 50% fresh BSFL + 50% commercial feed could be applied successfully in Thai frog cage production.
Chitosan Decelerates Melanosis in Shrimp: A Novel Technique for Visual Quality Assessment Using Digital Image Analysis
(2023) Kadak, Ali Eslem
The study aimed to determine the effects of chitosan, sodium metabisulfite, and citric acid against melanosis, which causes significant economic losses during the storage of shrimps. For this purpose, two different types of chitosan were extracted from tiger prawn shell wastes. The extracted chitosan was characterized by viscosity, FT-IR, XRD, SEM imaging, and color analyses. Prevention of melanosis formation was investigated by testing chitosan, sodium metabisulfite, and citric acid. To achieve this, fresh deep-water pink shrimp samples immersed in different solutions were stored for 12 days at 4℃. Melanosis formation in the samples was observed via color measurement, sensory evaluation, and image analysis. According to the results of the research, the deacetylation degrees of chitosans were found to be 99.50 and 89.51% and 76.31 and 78.24% by two different methods, respectively. Viscosities were measured as 0.34 and 4.17 cSt, respectively. Regarding the color parameters, the L* values were 83.68 and 78.94, a* values were 0.55 and 2.71, and b* values were 10.33 and 13.85, respectively. According to the sensory evaluation conducted throughout the study, melanosis formation was observed in all groups starting from the 6th day. On the 8th day, the control groups exceeded the acceptability threshold, and on the 12th day, melanosis formation spread throughout the body in all groups. The sensory evaluation results were supported by the color measurement and image analysis implemented for the first time in this study. The present study’s results showed that chitosan obtained from shellfish wastes decelerates melanosis formation as an alternative to commercially used chemicals.
Transcriptome analysis of the allometric growth of golden pompano (Trachinotus ovatus) following soybean meal feed
(2023) Liu, Bo; Liu, Bao-Suo; Guo, Hua-Yang; Yang, Jing-Wen; Zhang, Nan; Lin, Xian; Zhu, Ke-Cheng; Zhang, Dian-Chang
Golden pompano (*Trachinotus ovatus*) is a marine fish of great commercial value. It was selected for a study on allometric growth using fermented soybean meal (SBM) as the primary protein source during an 8-week culture period. By comparing the gene expression levels of different individuals in the fermented soybean meal group, we discovered that 1026 genes exhibited significant changes in slow and fast-growth individuals. Among these genes, 358 showed high expression levels, while 668 showed low ones. Subsequently, we conducted go function annotation and KEGG pathway enrichment analysis on all the significantly differentially expressed genes. This analysis revealed that many of these genes were associated with oxidative phosphorylation, steroid biosynthesis, glyceride metabolism, alanine, aspartic acid, and glutamate metabolism. Identifying these differentially expressed genes is a foundation for unraveling the molecular mechanisms behind growth and development. Additionally, it provides valuable gene data for future studies on the cloning and expression of growth-related genes and offers insights for subsequent biological research.
Efficacy of a formalin-inactivated vaccine against Lactococcus garvieae infection in golden pompano Trachinotus ovatus
(2023) Lv, Jing; Yang, Lindi; Li, Yanping; Yang, Shiping; Cai, Shuanghu; Jian, Jichang; Huang, Yucong
*Lactococcus garvieae* is one of the primary pathogens causing the severe disease to golden pompano (*Trachinotus ovatus*). Vaccination is the most effective measure of preventing the occurrence and spread of infectious diseases. However, no commercially available vaccine protects *T. ovatus* against *L. garvieae* infection. In the present study, the formalin-inactivated *L. garvieae* vaccines, consisting of bacterin alone (aqueous vaccine) and combined with oil adjuvant Montanide™ ISA 763 A VG (vaccine+763A), were prepared and administered to *T. ovatus* by intraperitoneal injection. The protective efficacy was evaluated by testing the relative percent survival (RPS), serum enzyme activity, and expression levels of immune-related genes in the tissues of *T. ovatus* after immunization. The results indicated that the relative percentage survival (RPS) values of aqueous vaccine and vaccine+763A were 80% and 90.8% at 8 weeks post-vaccination. The level of antibody titer, lysozyme activities, superoxide dismutase, and catalase in the two vaccinated fish groups increased significantly compared to that in the control group. Moreover, the expression levels of immune-related genes *IgM*, *TNF-α*, *IL-8*, *MHCI-α*, *MHCII*, *CD4*, *CD8α,* and *IL-1β* in all the tested tissues from *T. ovatus* were significantly enhanced after inoculation with aqueous vaccine and vaccine+763A. These findings demonstrated that the developed vaccine combined with oil adjuvant ISA 763 A VG improved immune responses and provided good protective efficacy against *L. garvieae* infection in the golden pompano culture.
Effects of biofloc technology on water quality and growth performance of Macrobrachium rosenbergii
(2023) Camarin, Ma-ann; Gonzaga, Alejandro; Jamis, Jhumar; Calpe, Adelaida
This study aimed to evaluate the effects of biofloc technology on the water quality and growth performance of *Macrobrachium rosenbergii*. The experiment was carried out over 165 days at the hatchery complex of the College of Fisheries and Aquatic Sciences, Mindanao State University-Marawi, Philippines. Postlarvae of *M. rosenbergii* (0.011±0.05 g) were stocked in 18 circular tanks (1200 L) consisting of six treatments under biofloc and non-biofloc systems in a completely randomized experimental design with tapioca flour as the carbohydrate source. Commercial pelletized sinking prawn feed with three dietary protein levels, viz., 42, 38, and 35% were chosen as experimental feeds. Results of the present study show that the water parameters were within the optimum range required in the culture of freshwater prawns. However, biofloc technology (BFT) did not influence sediment and water samples' dissolved oxygen, temperature, and pH values. On the other hand, total ammoniacal nitrogen (TAN) and nitrate showed significant variation (*p*\<0.05) among treatments, with higher values in the control treatment compared to the biofloc treatments. Moreover, the dietary protein level and carbohydrate addition had no significant effect on soil pH and organic carbon except for the soil total nitrogen value, where higher values were observed in the biofloc treatments. Furthermore, significantly higher mean prawn weight gain, net prawn yield, specific growth rate (SGR), and average daily weight gain (ADG) were recorded in the biofloc treatments compared to non-biofloc treatments. At the end of the culture period, there was 100% survival in all of the tanks. On the other hand, no significant variations were observed in feed conversion ratio (FCR) and protein efficiency ratio (PER) in the control treatment compared to the treatment with biofloc except in tanks using feed of 42% CP under the biofloc system. Therefore, based on the results of the present study, the use of BFT in the culture system of *M. rosenbergii*, helped reduce the protein percentage from 42 to 35, while maintaining the yield.
Study a natural co-infection case of Largemouth bass ranavirus, Aeromonas vickert, and Aeromonas hydrophila in Micropterus salmoides
(2023) Li, Yankai; Wei, Wenyan; Wu, Jianing; Liu, Shuya; Ren, Yonngiang; Huang, Xiaoli; Chen, Defang; Geng, Yi; Ouyang, Ping
The largemouth bass (LMB) is a significant aquaculture species widely cultivated in China. High-density culture has led to an increased susceptibility of LMB to infection by the opportunistic bacterium Aeromonas. This study investigates a case of natural co-infection with the Largemouth bass ranavirus (LMBV), Aeromonas veronii, and Aeromonas hydrophila in Sichuan Province, China. To identify the causative agents of the infection, two bacterial strains were isolated from diseased LMB specimens and identified through 16S rRNA sequencing as Aeromonas vickert and Aeromonas hydrophila, both of which are gram-negative bacteria. The infection of LMBV was confirmed through polymerase chain reaction (PCR) analysis of tissue samples from the infected fish. After two blind passes of the virus fluid, the typical cytopathological effect (CPE) can be observed. Phylogenetic analysis of the virus sequences showed the highest similarity with LMBV isolates (ON418985 and MW630113) from Guangdong Province, China. This study offers important insights into diagnosing mixed infections in LMB and provides a reference for future research.
Investigation of Reactive Red 198 Dye Removal by Chitosan from Aqueous Solution
(2023) Carbaş, Hamiyet Ö.; Kadak, Ali E.; Küçükgülmez, Aygül; Gülnaz, Osman; Çelik, Mehmet
This study used chitosan, a biopolymer with high adsorption capacity obtained from shrimp shells, to remove Reactive Red 198 dye from water. The effects of pH, temperature, dye concentration, and particle size on adsorption were investigated. The optimum pH level for the adsorption was determined as 5. The effect of the temperature was found to be adverse, and it was observed that the adsorption capacity of chitosan decreases as the temperature increases. Considering the effect of the initial dye concentration, the adsorption values of under-size chitosan (passed through a 150-mesh sieve) and over-size chitosan (retained on a 150-mesh sieve) at 200 mg/L dye concentration were 197.38 and 196.22 mg/g, respectively. At 100 mg/L dye concentration, these values were 97.41 and 96.10 mg/g, respectively. Adhesion of the Reactive Red 198 was easier because the adsorption surface area expanded with the reduction of the particle size of the chitosan. According to the results of the study, it was seen that the isotherm model of adsorption is a suitable monolayer for the Langmuir isotherm model. Langmuir isotherm's maximum adsorption capacity (Qmax) was calculated as 500 mg/g. The kinetic model was in line with the pseudo-second-order kinetic model. The FTIR spectra of the chitosan before and after adsorption showed that the adsorption is indeed chemical. Furthermore, SEM results demonstrated that the adsorption was more efficient due to the fibrous and porous structure of the chitosan.
Application of fuzzy model for the shelf-life determination of whole sea bass (Dicentrarchus labrax) under refrigerated temperatures
(2023) Genç, İsmail Y.
In this study, microbiological deterioration of whole sea bass stored at refrigerator temperatures (4°C) was determined through fuzzy modeling. Total Mesophilic Aerobic Bacteria (TMAB), Total Psychrophilic Aerobic Bacteria (TPAB), Lactic Acid Bacteria (LAB), *Pseudomonas sp*., and Enterobacteriaceae counts were observed during 12 days of storage. Quality Index Method (QIM) was used for sensory analysis of the samples and shelf life was determined according to sensory deterioration. The growth of the microorganisms was statistically significant (p\<0.05) at the end of the storage period. Additionally, significant differences (p\<0.05) were observed for QI scores after the 8^th^ day of the storage in whole sea bass stored under refrigerated conditions. A total of 12 rules were determined in the fuzzy logic application. Mamdani was used as the fuzzy type for fuzzy modeling, and centroid was used as the defuzzification method. Fuzzy membership values were computed using triangular membership functions. According to the research results, the shelf life of sea bass fish was determined as 8 days from the time of 12 days storage. As a result, it was observed that the sensory score could be determined by using Fuzzy logic (R^2^=0.96) according to microbiological parameters in sea bass stored in refrigerator conditions. In this context, it was concluded that Fuzzy logic could be used in shelf-life estimation in seafood products.
The use of sesame oil in sea bream feeds and its effects on growth and body chemical composition
(2023) Taşbozan, Oğuz; Erbaş, Celal; Tabakoğlu, Şefik S.; Yılmaz, Özgür; Atanasoff, Alexander; Gökçe, Mahmut A.
As fish oil availability declines worldwide and its price rises, there is a growing need to engage in scientific investigations into alternative oil sources for incorporation into fish feeds. This study aimed to determine the effects of dietary sesame oil on the growth performance, feed utilization, and nutritional composition of sea bream (*Sparus aurata*). Twenty-five individual fish (initial mean weight: 32.38±0.27 g) were placed in each tank in triplicate. Four experimental fish meal-based (iso-proteic 49% and iso-lipidic 20%) diets were formulated; the control (C) group contains 100% of fish oil (FO) and varying amounts (20, 40, 60%) of sesame oil (SO). During the 75-day experiment, the fish were fed 3 times a day, and the mean ambient temperature and dissolved oxygen values were measured as 22.5±0.5°C and 6.8±0.3 mg/L, respectively. At the beginning of the experiment, 20 fish were sampled to determine their nutrient composition and somatic indexes. In the end, 4 fish were collected for the same procedures and 4 for each tank's muscle and liver fatty acid compositions. At the end of the study, the S60 group exhibited the lowest final weight (FW) and feed utilization parameters. On the other hand, there were no statistical differences between FO, SO20, and SO40 in terms of FW. In addition, the SO40 group had the best feed conversion ratio (FCR) among the groups (P\<0.05). The whole-body lipid compositions of the groups were different. The highest lipid level was found in SO40 with 15.83±0.36%. Muscle and liver fatty acid composition was significantly affected by the fatty acid profile of experimental feeds. While total ω-6 fatty acids were higher in the SO groups than in group C, total ω-3 fatty acids were higher in the C group compared to the SO groups (P\<0.05). The ω-3/ω-6 ratios in the SO20 and SO40 groups showed similarity, while the highest ratio was observed in the control group (P\<0.05). As a result, according to data obtained from our study, it is predicted that 40% SO could be added to sea bream feed instead of FO in terms of growth performance, feed utilization, and nutritional composition.
Transcriptome analysis of Litopenaeus vannamei during the early stage of limb regeneration process
(2023) Yue, Wucheng; Yuan, Ruiming; Jang, Donghuo; Guo, Xiangzhao; Li, Fuhua; Qian, Xueqiao
Regeneration is a process in which organisms regrow new tissues or organs at the injury site, which has attracted the attention of many scientists and nonscientists. However, the underlying molecular mechanisms of regeneration after autotomy are largely unknown. In this study, we conducted RNA-seq sequencing on regenerated limb bud tissues of *Litopenaeus vannamei* at 0 hours post autotomy (0 hpa), 12 hours post autotomy (12 hpa), and 24 hours post autotomy (24 hpa). A total of 2,192 differentially expressed genes related to energy metabolism, transcription and translation, and epidermis development were identified between 0 hpa and 12 hpa, such as triosephosphate isomerase A, triosephosphate isomerase B, and zinc finger protein 367 that is upregulated in 12 hpa. Between 12 hpa and 24 hpa, 1,447 differentially expressed genes were identified that were related to cuticle development and energy metabolism, such as cuticle protein 6, which is upregulated in 24 hpa, and triosephosphate isomerase is downregulated in 24 hpa. The results indicated that energy metabolism, transcription and translation, epidermal formation, and chitin metabolism processes are involved during the early stage of limb regeneration. This study provides basic knowledge for investigating the molecular mechanisms associated with limb regeneration in crustaceans at the early regeneration stage.
Study on the Realization of Freshwater Ecosystem Services from the Perspective of Consumer Willingness to Pay in China
(2023) Dai, Yunyun; Zhou, Zhen; Yu, Lin; Yu, Yunbo; Yang, Hong
The realization of freshwater ecosystem services value plays a vital role in the survival of human beings and the sustainable development of fisheries, and this process is inseparable from the support of consumers. This paper decomposes freshwater ecosystem services in multiple dimensions. From the perspective of consumers' willingness to pay for ecosystem services, using the survey data of 821 consumers in China, the influence of various dimensions of freshwater ecosystem services on consumers' willingness is explored by the structural equation model. The results show that: (1) consumers already have a certain awareness of freshwater ecosystem services, but the proportion of consumers willing to pay extra for them is not high; (2) the individual characteristics (age, gender, education, and income ) affect consumers’ willingness to pay for freshwater ecosystem services value, but the impact degree is not high; (3) regulating, cultural, and provisional servers functions of freshwater ecosystem services significantly affect consumers’ willingness to pay, especially freshwater ecosystem services’ role on regulating carbon emissions, controlling algal biomass, enhancing local fishery culture and improving leisure and leisure entertainment services. This study is helpful to deeply understand consumers' willingness to pay for various dimensions of freshwater ecosystem services and provide more targeted and detailed guidance for realizing it.

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