• Volume 44,Issue 4,2020 Table of Contents
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    • Community structure of ichthyoplankton and its relationship with environmental factors in Daiquyang spawning ground

      2020, 44(4):606-620. DOI: 10.11964/jfc.20190411730

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      Abstract:The ichthyoplankton net was used to carry out the survey of fish eggs and larvae of Daiquyang between May 2010 and February 2012. According to the investigation results, 1 042 fish eggs and 2 055 fish larvae were collected, which belonged to 10 orders 19 families 37species. The dominant species of fish eggs were Auxis thazard and Eupleurogrammus muticus while fish larvae were Liza haematocheilus, Engraulis japonicas and Stolephorus chinensis. The average density of fish eggs in the surveyed areas was 8.40 ind./100 m3 while fish larvae was 14.85 ind./100 m3. The results of One-Way ANOVA showed that there were highly significant differences among the diversity index (H') in 4 seasons of spring and summer from 2010 to 2011, so were in the evenness index (J') and richness index (D). The CPUE of fish eggs and larvae showed uneven distribution, it was higher in spring and summer, but lowest in winter, which revealed that fish eggs and larvae resource density demonstrated a tendency of higher in the south stations and lower in the north stations. Pearson correlation analysis proved that the environmental factors most closely related to fish eggs and larvae were temperature, salinity and suspended matter. The results suggested that spring and summer were important seasons for fish spawning and Daiquyang areas were important spawning and nursery grounds for pelagic fishes such as E. japonicas, A. thazard and S. chinensis.

    • Tissue expression of lipid metabolism related genes PPARs and their responses to heat stress in turbot (Scophthalmus maximus)

      2020, 44(4):515-522. DOI: 10.11964/jfc.20190411747

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      Abstract:Scophthalmus maximus is a commercially valuable flatfish and one of most promising aquaculture species in Europe. Since S. maximus was introduced into China in 1990s, it has been a major maricultured fish in northern coastal areas of China. As a kind of cold-water fish, S. maximus has strict requirements for breeding temperature, which greatly limits the breeding range of this important marine fish. Therefore, it is of great research significance to explore the mechanism of heat-resistance in turbot. In this paper, tissue distribution of PPARs and the expression of PPARs in kidney at different temperature were analyzed by qPCR.The results showed that there are significant differences in the tissue distribution of the three subtypes of S. maximus PPARs. PPARα1 and PPARα2 were markedly expressed in the heart, PPARβ was widely distributed in various tissues of S. maximus, while PPARγ was significantly expressed in the gill of S. maximus. What's more, the transcript abundance of PPARs in S. maximus kidney showed different response patterns to the elevated temperature. At 20 ℃, the expression level of PPARα diminished dramatically and then increased with the elevated temperature. The expression of PPARβ was not significantly different at 14, 20, 23 and 25 ℃, however, its transcript abundance increased significantly when the temperature was increased to the lethal temperature of S. maximus at 28 ℃. The expression level of PPARγ showed a tendency to increase with increasing temperature. In summary, our results revealed that there are three subtypes PPARα, PPARβ and PPARγ in S. maximus, which may be involved in the regulation of lipid metabolism in a tissue-specific manner, and more importantly, the expression of three subtypes of PPARs under thermal stress was pointed out for the first time. Collectively, these studies will shed light on the regulation mechanism of PPARs on lipid metabolism in the kidney of S. maximus during heat stress, which will promote the further study of fish lipid metabolism.

    • Niche and interspecific associations of dominant fishes in southern coastal waters in Taizhou, China

      2020, 44(4):621-631. DOI: 10.11964/jfc.20190411721

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      Abstract:Based on the data from fishery resources survey carried out in southern coastal waters in Taizhou in October 2016 (autumn) and April 2017 (spring), this study defined the dominant species and main species that appeared in the two surveys as the dominant fish, and analyzed the niche and interspecific associations of dominant fish by the methods of index of relative importance, niche breadth, niche overlap, the variance ratio, Chi-square test, Pearson correlation test and Spearman rank correlation test. The results showed that there were 8 and 11 dominant fish species in autumn and spring respectively, and 5 common dominant fish species were in these two seasons. The index of niche breadth and overlap of dominant fish in autumn were slightly higher than those in spring. There were 4 wild niche species, 3 middle niche species and 1 narrow niche species in autumn, while 4 wild niche species, 5 middle niche species and 2 narrow niche species were in spring. The number of pairs with significant niche overlap in autumn accounted for 32.14% of the total pairs, while only 12.73% in spring. In autumn, overall interspecific associations indicated that significantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 1.50, 1.33 and 2.11 respectively, and the test significant rates were about 0%, 17.86% and 10.71% respectively. In spring, overall interspecific associations indicated that insignificantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 0.93, 0.90 and 1 respectively, and the test significance rates were about 9.1%, 18.18% and 21.82% respectively.

    • Prokaryotic protein expression of suppressor of cytokine signaling 1 of yellow catfish (Pelteobagrus fulvidraco) and preparation of their polyclonal antibodies

      2020, 44(4):523-527. DOI: 10.11964/jfc.20190611851

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      Abstract:Suppressor of cytokine signaling (SOCS) is a class of intracellular proteins that inhibited cytokine signaling. We cloned the sequence of SOCS1 gene from yellow catfish Pelteobagrus fulvidraco, whose length was 561 bp. We constructed the recombinant expression plasmid [pET32a (+)-SOCS1] carrying PfSOCS1 protein. The recombinant PfSOCS1 protein was optimally expressed by transformation into Escherichia coli BL21 (DE3) and then highly purified under inclusion body conditions. The polyclonal anti-PfSOCS1 antibodies were prepared by immunizing Balb/C mouse with recombinant PfSOCS1 protein, which could be used to recognize recombinant PfSOCS1 protein by Western blotting. The protein expression of PfSOCS1 was detected in kidney, intestine, liver and ovary, with relatively predominant level in the liver in P. fulvidraco.

    • Cloning and transcriptional regulation of tf and tfr1a promoters in Megalobrama amblycephala

      2020, 44(4):528-538. DOI: 10.11964/jfc.20190311709

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      Abstract:In order to explore the transcriptional regulation mechanism of the tf and tfr1a genes in Megalobrama amblycephala, the genomic sequences of tf and tfr1a were obtained from whole genome sequence database. Transcription factor binding sites and CpG islands in the promoter regions of tf and tfr1a genes were predicted by bioinformatics methods. Fragments of different length of the predicted promoter region of tf and tfr1a were cloned by PCR amplification. The amplified different fragments were ligated to the pGL3-Basic/pEGFP-1 vector. Subsequently, the recombinant plasmids were transiently transfected into Hela cells for fluorescence detection by the Dual-Luciferase Reporter System. Bioinformatics analysis showed that there was no CpG island site in the tf promoter, and there were two CpG island sites in the tfr1a promoter. A total of 9 tf and 10 tfr1a recombinant plasmids containing promoter fragments of different lengths were successfully constructed. The detection of Dual-Luciferase Reporter System showed that the core region of the tf promoter was -268—+56 bp, and the -1 308—-1 102 bp fragment may have a transcription factor binding site that positively regulates the gene expression. The core region of the tfr1a promoter was -224—+48 bp, and the +48—+92 bp region may contain negative regulatory elements that inhibit the transcription of this gene, while the -1 229—-1 219 bp region might contain positive regulatory transcription factor binding sites that promote the tfr1a gene expression.

    • Annual change of primary productivity in Apostichopus japonicus ponds by three water quality regulations

      2020, 44(4):632-641. DOI: 10.11964/jfc.20190511794

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      Abstract:The traditional water quality regulations could not break up thermocline and inhibit macroalgae growth, which result in poor water quality and Apostichopus japonicus growing poorly and even death. Jet water mixing (JWM) can break up thermocline and inhibit the growth of macroalgae. To study the purification efficiency and mechanism of JWM, the primary productivity in the ponds with a jet water mixer (JWM), a submerged aerator (SA) or without any artificial mixing (control) were studied. The results showed that the annual average primary productivity and P/R values of the pond with JWM were the highest, followed by SA pond, and the lowest in the pond without any artificial mixing (control). The mean annual primary productivity in the ponds with JWM, SA and Control pond were 6.22±0.54, 5.37±0.60 and 4.69±0.53 gO2/(m2·d), respectively. The primary productivity in the ponds decreased with the depth of water. There was no significant difference in primary productivity between 30-50 cm water layer and 50-100 cm water layer in JWM pond, while there was significant difference between the SA pond and Control pond (P<0.05). In addition, the primary productivity of the water layer of 50-150 cm in JWM pond was significantly higher than that of the SA and control pond (p<0.05) from June to September. Conclusion: compared with SA facility, JWM can improve significantly the primary productivity of the lower water layer, which can significantly improve the total primary productivity of the pond and facilitate the rapid circulation of the pond substances.

    • Identification and evolutionary analysis of Tc1/Mariner transposons in four catfish genomes

      2020, 44(4):539-550. DOI: 10.11964/jfc.20190111615

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      Abstract:To investigate the characteristics of Tc1/Mariner transposons in four catfish genomes (Ictalurus punctatus, Glyptosternum maculatum, Silurus asotus and S. meridionalis) and their role in the evolution, we used de novo and homology methods to predict Tc1/Mariner transposons and explored the role in the evolution of those four catfishes. The results showed that the contents of Tc1/Mariner transposons in the four catfishes were 9.46%, 2.70%, 7.83% and 8.54%, respectively. All the Tc1/Mariner transposons in the four catfishes were classified into 38, 20, 43 and 55 families, respectively. Based on the structural and phylogenetic analysis of the catalytic region of the transposase, the Tc1/Mariner transposons in the four catfishes can be classified into five different subgroups: Tc1 (DD34E), DD35E, DD36E, DD37E and pogo (DD35D). Phylogenetic analysis indicated that the transposons of most of the branches for S. asotus and S. meridionalis were clustered into sister groups. The results indicated that the insertion time of the majority Tc1/Mariner transposons mainly ranges between 0-5 Mya (million years ago). Many Tc1/Mariner transposons have a burst expansion between 0-1 Mya or 2-3 Mya. In addition, most of the Tc1/Mariner transposons in the four catfishes were inserted into the intron of the gene. In summary, this study provides new insights into the evolution of Tc1/Mariner transposons in the fish genomes.

    • Effects of dietary soybean meal on the intestinal microbiota and metabolic enzymes activities of microbial amino acids of Channa argus

      2020, 44(4):642-650. DOI: 10.11964/jfc.20181211583

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      Abstract:This study aimed to investigate the effect of soybean meal on the growth, intestinal microbiota composition and metabolic enzymatic activities of microbial amino acid of Channa argus. Four isonitrogenous and isoenergetic diets were formulated with soybean meal by replacing 0, 25%, 50% and 75% fish meal (G1, G2, G3 and G4, respectively). The fish of (8.65±0.25) g was hand-fed daily to satiation twice in cylindrical fiberglass tanks for 21 days. Results showed that no significant difference in survival rate was found among four groups. The growth performance of C. argus in G4 was significantly lower than those in G1 and G2, while the difference was not statistically significant between G3 and other three groups. The proportion of Firmicutes in the intestine of fish in G1 and G2 was significantly higher than that in G3, and the lowest was found in G4. The proportion of Proteobacteria in G1 and G2 was significantly lower than those in G3 and G4. The proportion of Lactococcus, Bacillus, Pseudomonas, Streptococcus, Laseczka and Acinetobacter in G4 was significantly lower than those in the other three groups. Additionally, the activities of glutamic-pyruvic transaminase and adenosine deaminase were the the highest in G4, while the activity of lactic dehydrogenase was the the highest in G1. All results indicated that, except for the effect on the growth of C. argus, dietary soybean meal significantly induced the changes in the intestinal microbiota composition and the activity of the microbial amino acid metabolic enzymes, which may provide theoretical basis for further understanding the application of soybean meal in the formulated diets of C. argus.

    • Molecular cloning and expression of sepiapterin reductase in Japanese ornamental carp (Cyprinus carpio var. koi)

      2020, 44(4):551-561. DOI: 10.11964/jfc.20190711869

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      Abstract:The origin of teleost skin color is from chromatophores. Different chromatophores synthesize distinct pigments, including melanin, carotenoid, pteridine and purine. Sepiapterin is a yellow pteridines, which could be transformed into tetrahydrobiopterin (BH4) and yellow/red pteridines pigments together with sepiapterin reductase (SPR), dihydrofolate reductase (DHFR) and other enzymes. SPR is the last enzyme in the process of de novo BH4 synthesis. In order to explore the function of spr in koi carp color formation, this study amplified the whole cDNA of spr and analyzed the spatio-temporal profile. Furthermore, we also detected the expression and distribution of SPR in the skin, fins and scales of koi carp with different colors by Western blot and immunochemistry methods. The results showed that the size of spr cDNA was 879 bp, including 132 bp and 134 bp 5' and 3' untranslated regions, and a 510 bp open reading frame encoding 170 amino acids. Sequences alignment and phylogenetic analysis revealed the spr gene of koi carp contained a adh_short_C2 conserved domain and had 97.65% similarity with gold fish. spr was expressed in every tissue, especially highest expressed in skin. In the four ontogenetic stages, the expression level of spr firstly decreased, then rose. The expression level of spr mRNA and protein in skins, fins and scales displayed the same condition among three colors (whole red koi carp, whole white koi carp and kohaku koi carp). The highest expression level was detected in whole red koi carp and rarely in white skin, fins and scales of kohaku koi carp. The immunohistochemical positive signals were detected in both skins of whole red and whole white koi carp, and intensively exhibited in red skin compared with white skin. All the results might indicate that the spr gene has relationship with the xanthophores/erythrophores differentiation and formation, involved in koi carp color formation.

    • Effects of mixed culture of Lactobacillus as water additive on the environment of pond, and the health of intestine and gill of tilapia(Oreochromis niloticus)

      2020, 44(4):651-660. DOI: 10.11964/jfc.20190411733

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      Abstract:To provide a basis for the application of Lactobacillus in the healthy aquaculture of tilapia, the effects of mixed culture of Lactobacillus as water additive on the environment of pond, and the health of intestine and gill of tilapia were studied. Mixed culture of Lactobacillus was added to the water of tilapia (Oreochromis niloticus) pond (control group: 0; experimental group: with a final concentration of 1.0×104 cfu/mL) for ten weeks. The components of mixed culture of Lactobacillus were Lactobacillus casei and Lactobacillus acidophilus, with a 1:2.2 ratio. The water quality of pond, immune and antioxidant indexes of the intestine and gill of tilapia were monitored. High throughput sequencing technique (Illumina Miq) was used to compare the community structure of microbiota in water, sediment, intestine and gill mucosa of tilapia between the control and the experimental group. The results showed that the nitrate content in the water samples of the experimental group was lower than that of the control group. From the seventh week, and the nitrate content in the water samples of the experimental group was 72.68% (P< 0.05), 72.00% (P>0.05), 26.27% (P>0.05) and 21.46% (P>0.05) lower than that of the control group, respectively. The total nitrogen content in the water samples of the experimental group was 43.39% (P>0.05), 44.64% (P>0.05), 15.64% (P>0.05), 37.57% (P>0.05) and 34.49% (P>0.05) lower than that of the control group from the sixth week, respectively. The total phosphorus content in the water samples of the experimental group was 40.91% (P>0.05), 33.33% (P>0.05), 50.00% (P>0.05), 33.33% (P>0.05), 17.39% (P>0.05), 39.29% (P< 0.05) and 25.71% (P>0.05) lower than that of the control group from the fourth week, respectively. Compared with the control group, the activity of alkaline phosphatase (AKP) in the intestine of tilapia in the experimental group increased by 45.04% (P< 0.05), and the total superoxide dismutase (SOD) and AKP in the gill of tilapia in the experimental group increased by 58.26% (P< 0.05) and 60.99% (P< 0.05), respectively. Mixed culture of Lactobacillus influenced the community structure of microbiota of pond water, but did not affect that of sediment. Microbiota of intestine and gill of tilapia were affected by the probiotics, among which, the conditional pathogens, Acinetobacter and Pantoea were decreased, while the beneficial bacteria, Cetobacterium was increased. Using mixed culture of Lactobacillus as water additive could improve water quality, the immunity and antioxidant capacity of intestine and gill of tilapia, and regulate the community structure of microbiota of intestine and gill of tilapia.

    • Yellow spot disease in Pyropia species infected by Vibrio mediterranei 117-T6

      2020, 44(4):661-671. DOI: 10.11964/jfc.20190711865

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      Abstract:Pyropia species were the most popular algae cultivated in China with great commercial importance. Yellow spot disease (YSD) was a high-incidence infectious disease in the conchocelis filament sporing stage of Pyropia, which seriously affects the production. In this paper, the free living conchocelis filament of Pyropia haitanensis were infected by Vibrio mediterranei 117-T6, a YSD pathogen. The effects of environmental factors on the growth of the strain and its infectious ability were studied. The activities of SOD, POD and the contents of phycobiliprotein, chlorophyll a (Chl. a), soluble protein, free proline (Pro) and malondialdehyde (MDA) in the algae were measured under susceptible infectious conditions. The results showed that the optimum growth conditions of V. mediterranei 117-T6 were 30 ℃, pH 7.0 and salinity 20, while the most susceptible infectious conditions were temperature 30 ℃, pH 6.0 and salinity 20. After it was infected by V. mediterranei 117-T6 under the susceptible infectious conditions for 12 hours, the activity of SOD, POD, the content of phycobiliprotein, soluble protein and free proline in P. haitanensis conchocelis filaments were significantly higher than those in the control group (P<0.05). The content of MDA reached the highest value at 6 hours and was significantly higher than that in the control (P<0.05). After being infected for 24 hours, the content of Chl a in the infectious group achieved the highest, which was significantly higher than that in the control group (P<0.05). The study showed that in a short period, V. mediterranei 117-T6 could stimulate the algae to produce stress-response reactions. However, with the estension of the infection, the reactive oxygen species and osmotic pressure in the algae caused by pathogen increased and finally could lead to the death of Pyropia. Adverse environmental factors such as high temperature and acidification can exacerbate the infectious ability of V. mediterranei 117-T6, and the secondary factors were temperature, pH and salinity. The results suggested that the comprehensive treatment of Pyropia YSD should be carried out from the two aspects: the environment and the pathogenic bacteria.

    • Cloning and characterization of cytochrome P450 302a1 (CYP302a1) during molting stages in Macrobrachium rosenbergii

      2020, 44(4):562-574. DOI: 10.11964/jfc.20190711868

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      Abstract:The molting process is an essential physiological process in crustaceans that is closely related to the synthesis of ecdysteriods. Cytochrome P450(CYP)302a1 is the key enzyme which plays a critical role in the synthesis of ecdysteriods. Here we present the cloning and characterization of CYP302a1 gene from Macrobrachium rosenbergii (Mr-CYP302a1). The acquired gene was 1 859 bp in full-length with the open reading frame (ORF) of 1 629 bp that encodes 543 amino acids (aa) with a molecular weight of 61.09 ku and an isoelectric point of 8.42. The aa sequence analysis revealed that there were five P450 characteristic conserved regions, i.e., heme-binding, helix-K, helix-C, helix-I, and PERF. Phylogenetic analysis demonstrated that Mr-CYP302a1 was closely related to the CYP302a1 of Neocaridina denticulata, and then clustered with the CYP302a1 from Decapoda crustaceans such as Litopenaeus vannamei and Portunus trituberculatus. Real-time quantitative PCR (qRT-PCR) results showed that Mr-CYP302a1 was expressed in almost all the tissues tested with significantly higher expression levels in the Y-organ. On the other hand, the expression of Mr-CYP302a1 was significantly lower at the postmolt stage (stages A and B), and it was increased gradually at the intermolt (stage C), significantly enhanced and reached the maximal level at the D1 stage. Mr-CYP302a1 was expressed and its polyclonal antibody was generated. Western blot (WB) showed that the expression of Mr-CYP302a1 protein was the highest in Y- organs of M. rosenbergii. The expression level of Mr-CYP302a1 protein also reached a peak at D1 stage during the molting process. In summary, our results indicate that Mr-CYP302a1 may play an important role in molting of M. rosenbergii.

    • Isolation and identification of pathogens of ulcer disease in Cynoglossus semilaevis

      2020, 44(4):672-680. DOI: 10.11964/jfc.20190711874

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      Abstract:In this study, 40 bacterial strains were isolated from the intestinal tract and surface lesions of the diseased Cynoglossus semilaevis with 2216E and TCBS medium. The hemolytic activity of the strains was tested, and three strains i.e. Vibrio harveyi, V. alginolyticus and V. parahaemolyticus with the strongest hemolysis activity were screened and identified as the three potential pathogenic strains in vitro. By co-culturing the three kinds of potential pathogenic bacteria with the intestinal epithelial cells of the healthy C. semilaevis, the relative expression of the immune genes and the apoptosis rate of the intestinal epithelial cells after co-culture were detected separately to evaluate the pathogenicity of these strains at the cellular level. The results showed that the expression of interleukin-10 gene (IL-10) in intestinal epithelial cells was significantly up-regulated after being stimulated with V. harveyi, suggesting that V. harveyi elicited the most intense immune response after co-culturing, and the apoptosis rate of the intestinal epithelial cells after co-culture with V. harveyi, V. alginolyticus and V. parahaemolyticus was 48.3%, 36% and 34.5%, respectively. It is speculated that V. harveyi is a highly pathogenic strain of C. semilaevis ulcer disease. Finally, the results of the artificial infection showed that the mortality rates of V. harveyi, V. alginolyticus and V. parahaemolyticus were 100% and 95% and 75% respectively on the sixth day after artificial re-infection of C. semilaevis, which is consistent with the results of the cellular level test. The study indicated that the three Vibrio strains screened in this experiment had strong toxicity and pathogenicity, especially the pathogenicity of V. harveyi was the strongest, and it is speculated that C. semilaevis ulcer disease may be caused by co-infection of various pathogenic bacteria.

    • Effect of KK-42 on the carapace ultrastructure in Macrobrachium nipponense during postmolt

      2020, 44(4):575-580. DOI: 10.11964/jfc.20190311677

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      Abstract:In order to further investigate the effect of KK-42 on cuticle structure, the juvenile prawns (Macrobrachium nipponense) in postmolt stage during which the formation of exocuticle gradually ends but that of endocuticle starts, were employed to study the structures of carapace exocuticle and endocuticle using the observation of paraffin section by scanning electron microscopy (SEM). Healthy intermolt M. nipponense with body length of (3.5±0.1) cm were randomly divided into two groups. The M. nipponense were soaked for 1 min in KK-42 solution at a concentration of 1.95×10-4 mol/L (treatment group) or 0 mol /L (control group), respectively. The carapaces of M. nipponense at 1.5, 3.0, 6.0 and 12.0 h after molting were obtained to be used for ultrastructural observation. To observe directly the surface structure of endocuticle, the carapace obtained at 6.0 h after molting was scraped gently with an anatomical knife to remove tissues on the inner surface of carapace, and then examined using SEM. The results showed that the carapace was only composed of the epicuticle and exocuticle at 1.5 and 3.0 h after molting. The number of exocuticle lamellae derived from KK-42 treatment group rose significantly at 1.5 and 3.0 h after molting, and the thickness of exocuticle increased by 72.07% and 38.67%, respectively, compared with the corresponding control group. At 6 and 12 h after molting, the loose lamellae in exocuticle tended to be dense, and there was no significant difference in thickness to be found between two groups. The number of endocuticle lamellae with a loose structure, being only one at 6.0 h, separately increased to two in control group and three in treatment group at 12.0 h after molting. In addition, pore canals within the endocuticle presented different sizes and head-tail orientation. No significant structural change was observed in the endocuticle after KK-42 treatment. The results reveal that KK-42 has a significant effect on the carapace ultrastructure of juvenile M. nipponense during postmolt, and accelerate the formation rate of the exocuticle as well as endocuticle.

    • Supplementary study on reproductive biology and life cycle of Sargassum fusiforme (Phaeophyceae)

      2020, 44(4):581-595. DOI: 10.11964/jfc.20190111639

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      Abstract:In this research, the biological characteristics and life cycle of Sargassum fusiformis, including the sexual reproduction of its mature sporophytes, asexual reproductions of its rhizoids and lateral branches were comprehensively studied. The meiosis and mitosis of the eggs, sperm and fertilized eggs of maricultural and natural S. fusiformis in Dongtou coastal waters were recorded in detail. In addition, the growth, development and differentiation of organs such as rhizoids, stems (main stem and lateral stem), leaves (air-bladders) and receptacles (female and male), as well as the morphology and structure features of embryos, young and mature sporophytes of S. fusiformis were described. On this basis, the existing reproductive biology and life cycle of S. fusiformis were partially supplemented and revised. The contents about asexual reproduction of S. fusiforme lateral branches and sexual reproduction of young S. fusiforme sporophytes were supplemented, and the life cycle diagrams of sexual and asexual reproduction of S. fusiforme were redrawn. The results of this study laid a foundation for the study of the maricultural ecology and the reproductive rhythm of S. fusiformis, as well as the population reproduction and its relationship to environmental factors.

    • Attractive effects for different positions and orientations of fishway entrance

      2020, 44(4):681-689. DOI: 10.11964/jfc.20190411735

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      Abstract:In order to find out the influence of different entrance orientations and positions on fish attractive effect, a generalized model of fishway entrance was established and three environmental velocity conditions were designed in this paper. Tests were carried out at fishway entrances of different orientations and positions. The results showed that the fishway entrance in the direction perpendicular to the river flow had better attractive effect than that in the direction parallel to the river flow at the same fishway entrance; When the fishway is located in the middle of the river, the closer the fishway entrance is to the tail water from the power station, the better the fish luring effect will be; In all conditions, when the environmental velocity is 0.3 m/s, there is the best attractive effect for the fishway entrance. The research results will have important reference significance for the layout of fishway entrance in hydraulic engineering and guide the engineering practice.

    • >ROUNDUPS
    • Research progress on the effects of hypoxia stress on crustacean and its molecular regulation

      2020, 44(4):690-704. DOI: 10.11964/jfc.20191112052

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      Abstract:Oxygen is the most critical condition for animal’s life activities. When animals are exposed to hypoxia environment, the biochemical reaction and physiological function of the animals will correspondingly change, which can finally cause a series of metabolic disorders and damage to organisms or even death. Hypoxia stress mechanism is complex physiological regulation process involving multiple genes and regulated by fine-tuning. Hypoxia stress and molecular adaptation mechanism of crustaceans are unclear compared with mammals. In this paper, the causes of hypoxia stress were analyzed, and stress reacting process and physiological adaptation strategies of crustaceans in response to hypoxia, as well as the effects of hypoxia on behavior, survival, antioxidant ability, metabolic reaction, and molecular mechanisms of hypoxia stress of crustacean were described and reviewed. In addition, the molecular mechanism in response to hypoxia was discussed from HIF-1 (hypoxia-inducible factor 1) signaling pathway, AMPK (adenosine 5'-monophosphate (AMP)-activated protein kinase) signaling pathway and apoptosis pathway. On this basis, the multiple measures are necessary to prevent and regulate negative effects of hypoxia stress, including the breeding hypoxia-resistant variety, and nutritional regulation. This paper may provide a theoretical reference for people to deeper understand the mechanism of hypoxia stress and molecular adaptation in crustaceans.

    • >PAPERS
    • Biomass particle size spectrum of fish in the Jiaozhou Bay

      2020, 44(4):596-605. DOI: 10.11964/jfc.20180811435

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      Abstract:In order to understand the grain size structure characteristics of fish communities in the Jiaozhou Bay, in this study, we constructed the biomass particle size spectrum of fish in this area based on the data collected from the four submarine trawl surveys performed during 2016 to 2017. The heterogeneities of the characteristic parameters of biomass particle size spectrum of fish in four seasons were analyzed and compared. The results showed that the Sheldon-type biomass particle size spectrum of fish in the Jiaozhou Bay displayed the unimodal pattern, with the fish particle sizes being ranged from −3 to 10 grain size, showing a relatively uniform particle size distribution spectrum and the highest peak was on the 5-6 grain size. It is mainly composed of small fish, such as Hexagrammos otakii and Sebastiscus marmoratus. There was a significant difference in the degree of curve and curvature of the normalized biomass particle size spectrum of each season. Among them, the spring curvature was the largest and the curve was gentle whereas the summer curvature was the smallest and the curve was relatively steep. The degree of curve and curvature of the curve were mainly related to the presence of a large number of endemic perennial species, such as Liparis tanakae, Ammodytes personatus, and Cryptocentrus filifer as well as the seasonal migratory fish, such as Thrissa kammalensis, and Argyrosomus argentatus. The ABC curve indicated that the spring was in an undisturbed state, the winter was in a moderately disturbed state whereas the summer and autumn were in a state of severe disturbance. These results indicated that the fish biomass spectrum in Jiaozhou Bay was unimodal, and the particle size structure was mainly small-sized fish. The number and size of supplementary populations such as local perennial and seasonal migratory fish affected the peak type and curvature of the biomass particle size spectrum of fish in the Jiaozhou Bay.

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