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Jian-fang Gui - One of the best experts on this subject based on the ideXlab platform.

  • Complete genome sequence and architecture of Crucian Carp Carassius auratus herpesvirus (CaHV).
    Archives of virology, 2016
    Co-Authors: Xiao-tao Zeng, Zhong-yuan Chen, Yuan-sheng Deng, Jian-fang Gui, Qi-ya Zhang
    Abstract:

    Crucian Carp Carassius auratus herpesvirus (CaHV) was isolated from diseased Crucian Carp with acute gill hemorrhages and high mortality. The CaHV genome was sequenced and analyzed. The data showed that it consists of 275,348 bp and contains 150 predicted ORFs. The architecture of the CaHV genome differs from those of four cyprinid herpesviruses (CyHV1, CyHV2, SY-C1, CyHV3), with insertions, deletions and the absence of a terminal direct repeat. Phylogenetic analysis of the DNA polymerase sequences of 17 strains of Herpesvirales members, and the concatenated 12 core ORFs from 10 strains of alloherpesviruses showed that CaHV clustered together with members of the genus Cyprinivirus, family Alloherpesviridae.

  • sequence analysis and subcellular localization of Crucian Carp carassius auratus viperin
    Fish & Shellfish Immunology, 2014
    Co-Authors: Bing Wang, Yibing Zhang, Tingkai Liu, Jian-fang Gui
    Abstract:

    Human viperin is known as an interferon (IFN)-inducible antiviral protein and localizes to endoplasmic reticulum (ER) via its N-terminal amphipathic alpha-helix. Little is known about subcellular localization of fish viperin. Herein, we characterized subcellular localization of a fish viperin from Crucian Carp Carassius auratus. Crucian Carp viperin is nearly identical to the other viperin proteins in sequence, with the exception of the first N-terminal 70 amino acids that are defined as N-terminal variable domain including an amphipathic alpha-helix. In addition to N-terminal variable domain, Crucian Carp viperin protein harbors a conserved middle radical SAM domain and a conserved C-terminal domain. Subcellular localization analyses indicate that Crucian Carp viperin is a cytoplasmic protein associated with ER. Sequence analyses reveal that amino acids 1-74 forms an amphipathic alpha-helix domain that drives ER-localization of Crucian Carp viperin. In addition, Coimmunoprecipitation assays show that Crucian Carp viperin proteins are able to self-associate. These results together indicate that similar to mammalian homologs, fish viperins likely play important roles in IFN response. (C) 2014 Elsevier Ltd. All rights reserved.

  • subcellular localization and functional characterization of a fish irf9 from Crucian Carp carassius auratus
    Fish & Shellfish Immunology, 2012
    Co-Authors: Jun Shi, Tingkai Liu, Yibing Zhang, Fan Sun, Jian-fang Gui
    Abstract:

    Mammalian interferon (IFN) regulatory factor 9 (IRF-9) has long been recognized as the DNA sequence recognition subunit of IFN-stimulated gene factor 3 (ISGF3) complex, which is critical for type I IFN to induce the expression of IFN-stimulated genes (ISGs) against viral infection. Recent studies have shown that fish IFN exerts antiviral effects by induction of a number of ISGs and also of itself; however, little is known about the role of fish IRF9 in IFN signaling. Here we identify a fish IRF9 orthologue (CaIRF9) from IFN-producing cell line, Crucian Carp Carassius auratus blastulae embryonic (CAB) cells. Analysis of subcellular distribution of CaIRF9-green fluorescent protein indicates that CaIRF9 is constitutively present in the nucleus, which is driven by two nuclear localization signals (NLS), one locating within DNA-binding domain (DBD) of CaIRF9 and the other immediately behind DBD, although human IRF9 contains only one NLS analogous to the former of CaIRF9. Overexpression of CaIRF9 together with CaSTAT2 not only activates ISRE-containing promoter but also upregulates the expression of fish ISGs. Strikingly, CaIRF9 together with CaSTAT2 also exhibits an ability to activate Crucian Carp IFN promoter, and blockade of cellular CaIRF9 attenuates IFN itself-induced activation of Crucian Carp IFN promoter. Taken together, these data suggest that Crucian Carp IFN induces the expression of ISGs and also of itself possibly by the JAK-STAT signaling pathway that is conserved from fish to mammals. (C) 2012 Elsevier Ltd. All rights reserved.

  • subcellular localization and functional characterization of a fish irf9 from Crucian Carp carassius auratus
    Fish & Shellfish Immunology, 2012
    Co-Authors: Jun Shi, Tingkai Liu, Yibing Zhang, Fan Sun, Jian-fang Gui
    Abstract:

    Mammalian interferon (IFN) regulatory factor 9 (IRF-9) has long been recognized as the DNA sequence recognition subunit of IFN-stimulated gene factor 3 (ISGF3) complex, which is critical for type I IFN to induce the expression of IFN-stimulated genes (ISGs) against viral infection. Recent studies have shown that fish IFN exerts antiviral effects by induction of a number of ISGs and also of itself; however, little is known about the role of fish IRF9 in IFN signaling. Here we identify a fish IRF9 orthologue (CaIRF9) from IFN-producing cell line, Crucian Carp Carassius auratus blastulae embryonic (CAB) cells. Analysis of subcellular distribution of CaIRF9-green fluorescent protein indicates that CaIRF9 is constitutively present in the nucleus, which is driven by two nuclear localization signals (NLS), one locating within DNA-binding domain (DBD) of CaIRF9 and the other immediately behind DBD, although human IRF9 contains only one NLS analogous to the former of CaIRF9. Overexpression of CaIRF9 together with CaSTAT2 not only activates ISRE-containing promoter but also upregulates the expression of fish ISGs. Strikingly, CaIRF9 together with CaSTAT2 also exhibits an ability to activate Crucian Carp IFN promoter, and blockade of cellular CaIRF9 attenuates IFN itself-induced activation of Crucian Carp IFN promoter. Taken together, these data suggest that Crucian Carp IFN induces the expression of ISGs and also of itself possibly by the JAK-STAT signaling pathway that is conserved from fish to mammals.

  • molecular cloning and characterization of Crucian Carp carassius auratus l interferon regulatory factor 7
    Fish & Shellfish Immunology, 2003
    Co-Authors: Yibing Zhang, Qi-ya Zhang, Jing Zhang, Guoping Huang, Lihua Wei, Jian-fang Gui
    Abstract:

    Interferon (IFN) can induce an antiviral state via interferon-regulatory transcription factors (IRFs), which bind to and control genes directed by the interferon-stimulated response element (ISRE). Here we describe a fish IRF, termed CaIRF7, cloned from a subtractive cDNA library which is constructed with mRNAs obtained from Crucian Carp (Carassius auratus L.) blastulae embryonic (CAB) cells infected by UV-inactivated GCHV and mock-infected cells. CaIRF7 cDNA was found to be 1816 bp in length, with a 42 bp 5'UTR and a 508 bp 3'UTR. The open reading frame translates into 421 amino acids in which a DNA-binding domain (DBD) containing the repeated tryptophan motif and IRFs association domain have been identified. Like chicken GgIRF3, CaIRF7 was most similar to mammalian IRF7 with 27 to 30% identity overall and some 37% identity in their DBDs. A single transcript of 1.9 kb was detected in virally induced CAB cells by virtual Northern blotting. RT-PCR analysis revealed a wide tissue distribution of CaIRF7 constitutive expression, with detectable transcript in non-infected CAB cells and various tissues of healthy Crucian Carp. In addition, CaIRF7 expression was differentially increased by stimulation of the CAB cells with active GCHV, UV-inactivated GCHV or CAB IFN, indicating that the activation of CaIRF7 was directly regulated by IFN.

Rosetta C Blackman - One of the best experts on this subject based on the ideXlab platform.

  • assessing the impact of the threatened Crucian Carp carassius carassius on pond invertebrate diversity a comparison of conventional and molecular tools
    Molecular Ecology, 2020
    Co-Authors: Lori Lawson Handley, Carl D Sayer, Lynsey R Harper, Daniel S Read, Rosetta C Blackman, Marco Benucci
    Abstract:

    Fishes stocked for recreation and angling can damage freshwater habitats and negatively impact biodiversity. The pond-associated Crucian Carp (Carassius carassius) is rare across Europe and is stocked for conservation management in England, but its impacts on pond biota are understudied. Freshwater invertebrates contribute substantially to aquatic biodiversity, encompassing many rare and endemic species, but their small size and high abundance complicate their assessment. Practitioners have employed sweep-netting and kick-sampling with microscopy (morphotaxonomy), but specimen size/quality and experience can bias identification. DNA and environmental DNA (eDNA) metabarcoding offer alternative means of invertebrate assessment. We compared invertebrate diversity in ponds (N = 18) with and without Crucian Carp using morphotaxonomic identification, DNA metabarcoding and eDNA metabarcoding. Five 2 L water samples and 3 min sweep-net samples were collected at each pond. Inventories produced by morphotaxonomic identification of netted samples, DNA metabarcoding of bulk tissue samples and eDNA metabarcoding of water samples were compared. Alpha diversity was greatest with DNA or eDNA metabarcoding, depending on whether standard or unbiased methods were considered. DNA metabarcoding reflected morphotaxonomic identification, whereas eDNA metabarcoding produced markedly different communities. These complementary tools should be combined for comprehensive invertebrate assessment. Crucian Carp presence minimally reduced alpha diversity in ponds, but positively influenced beta diversity through taxon turnover (i.e., ponds with Crucian Carp contained different invertebrates to fishless ponds). Crucian Carp presence contributes to landscape-scale invertebrate diversity, supporting continued conservation management in England. Our results show that molecular tools can enhance freshwater invertebrate assessment and facilitate development of more accurate and ecologically effective pond management strategies.

  • assessing the impact of the threatened Crucian Carp carassius carassius on pond invertebrate diversity a comparison of conventional and molecular tools
    bioRxiv, 2020
    Co-Authors: Lynsey R Harper, Lori Lawson Handley, Carl D Sayer, Daniel S Read, Rosetta C Blackman, Marco Benucci, Matthew J Hill, Bernd Hanfling
    Abstract:

    Fishes stocked for recreation and angling can damage freshwater habitats and negatively impact biodiversity. The pond-associated Crucian Carp (Carassius carassius) is rare across its native European range and has been stocked for conservation management in England despite plausible non-native status. However, its impacts on English pond biota have not been broadly assessed. Freshwater invertebrates comprise a large proportion of aquatic biodiversity, encompassing many rare and endemic species, but small size and high abundance complicates their assessment. Practitioners have typically employed sweep-netting and kick-net sampling with microscopy, but specimen size/quality and experience can bias identification. DNA and eDNA metabarcoding now offer alternative means of invertebrate assessment. We compared invertebrate diversity in ponds (N = 18) with and without Crucian Carp using sweep-netting and microscopy, DNA metabarcoding, and eDNA metabarcoding. Five 2 L water samples and 4 minute sweep-net samples were collected at each pond. Inventories produced by morphotaxonomic identification of netted samples, DNA metabarcoding of bulk tissue samples, and eDNA metabarcoding of water samples were compared. Alpha diversity was greatest with DNA or eDNA metabarcoding, depending on whether methods were considered as standard or with potential biases removed. DNA metabarcoding reflected morphotaxonomic identification, whereas eDNA metabarcoding produced markedly different communities. Therefore, these complementary tools should be combined for comprehensive freshwater invertebrate assessment. Crucian Carp presence minimally reduced alpha diversity in ponds, but positively influenced beta diversity through taxon turnover (i.e. ponds with Crucian Carp contained different invertebrate taxa to fishless ponds). Concerning pond invertebrates, the Crucian Carp can be considered a naturalised, non-impactful species in England, supporting continued conservation management in this region. Our results show that molecular tools can enhance freshwater invertebrate assessment and facilitate development of more accurate and ecologically effective pond management strategies.

  • development and application of environmental dna surveillance for the threatened Crucian Carp carassius carassius
    Freshwater Biology, 2019
    Co-Authors: Lynsey R Harper, Lori Lawson Handley, Carl D Sayer, Nathan P Griffiths, Daniel S Read, Kirsten J Harper, Rosetta C Blackman, Bernd Hanfling
    Abstract:

    The Crucian Carp (Carassius carassius ) is one of few fish species associated with small ponds in the UK. These populations contain genetic diversity not found in Europe and are important to conservation efforts for the species which has declined across its range in Europe. Detection and monitoring of extant Crucian Carp populations are crucial for conservation success. Environmental DNA (eDNA) analysis could be very useful in this respect as a rapid, cost‐efficient monitoring tool. We developed a species‐specific quantitative polymerase chain reaction (qPCR) assay for eDNA surveillance of Crucian Carp to enable non‐invasive, large‐scale distribution monitoring. We compared fyke netting and eDNA analysis at ponds with (n = 10) and without (n = 10) Crucian Carp for presence–absence detection. We examined biotic (Crucian Carp density represented by catch‐per‐unit‐effort [CPUE] estimate) and abiotic influences on eDNA detection probability using a hierarchical occupancy model, and eDNA quantification using a mixed‐effects model. eDNA analysis achieved 90% detection for Crucian Carp (n = 10), failing in only one pond where presence was known. CPUE estimate and conductivity had positive and negative influences on eDNA detection probability in qPCR replicates respectively. Similarly, conductivity had a negative effect on DNA copy number, whereas copy number increased with CPUE estimate. Our results demonstrate that eDNA analysis could enable detection of Crucian Carp populations in ponds and benefit ongoing conservation efforts, but imperfect species detection in relation to biotic and abiotic factors and eDNA workflow requires further investigation. Nonetheless, we have established an eDNA framework for the Crucian Carp as well as sources of imperfect detection which future investigations can build upon.

Jin Zhao - One of the best experts on this subject based on the ideXlab platform.

  • shelf life extension of Crucian Carp carassius auratus using natural preservatives during chilled storage
    Food Chemistry, 2012
    Co-Authors: Xuguang Zhang, Jin Zhao
    Abstract:

    Abstract The effect of the natural preservatives, tea polyphenols and rosemary extract, on microbiological [total viable count (TVC)], chemical [pH, total volatile base nitrogen (TVB-N), K -value and thiobarbituric acid (TBA) values], texture and sensory changes of air-packaged whole Crucian Carp ( Carassius auratus ) stored at 4 ± 1 °C was investigated for 20 days. The shelf-life of Crucian Carp was found to be 7–8 days for untreated group (control), 13–14 days for tea polyphenols group and 15–16 days for rosemary extract treated group according to sensory assessment results, for which the corresponding microbiological assessment also showed an increased shelf-life. Meanwhile, the increases of pH, TVB-N, K -value and TBA values were significantly delayed in both treated groups of samples compared to the control group. Thus, either tea polyphenols or rosemary extract could be used as potential preservatives to extend the shelf-life of Crucian Carp during chilled storage.

Zaizhao Wang - One of the best experts on this subject based on the ideXlab platform.

  • molecular mechanism of endocrine system impairment by 17α methyltestosterone in gynogenic pengze Crucian Carp offspring
    Ecotoxicology and Environmental Safety, 2016
    Co-Authors: Yao Zheng, Jiazhang Chen, Yan Liu, Jiancao Gao, Yanping Yang, Yingying Zhang, Xuwen Bing, Zexia Gao, Hongwei Liang, Zaizhao Wang
    Abstract:

    The effects of synthetic androgen 17α-methyltestosterone (MT) on endocrine impairment were examined in Crucian Carp. Immature 7-month old mono-female Pengze Crucian Carp (Pcc) F2 offspring were exposed to 50 and 100 μg/L of MT (week 2, 4, and 8). Gonadosomatic index, hepatosomatic index and intestine weight altered considerably and oocyte development was repressed. In the treatment groups, ovarian 11-ketotestosterone decreased, whereas 17β-estradiol and testosterone increased, and ovarian aromatase activities increased at week 4. However, in the brain tissue, those values significantly decreased. Quantitative RT-PCR analysis demonstrated changes in steroid receptor genes and upregulation of steroidogenic genes (Pcc-3bhsd, Pcc-11bhsd2 Pcc-cyp11a1), while the other three steroidogenic genes (Pcc-cyp17a1, Pcc-cyp19a1a and Pcc-star) decreased from week 4 to week 8. Ovarian, hepatic Pcc-vtg B and vitellogenin concentration increased in both 50 and 100 μg/L of MT exposure groups. This study adds further information regarding the effects of androgens on the development of previtellogenic oocytes, which suggests that MT could directly target estrogen signaling pathway, or indirectly affect steroidogenesis and vitellogenesis.

  • molecular cloning of pcc dmrt1s and their specific expression patterns in pengze Crucian Carp carassius auratus var pengze affected by 17α methyltestosterone
    Fish Physiology and Biochemistry, 2014
    Co-Authors: Yao Zheng, Hongwei Liang, Zaizhao Wang
    Abstract:

    Dmrt1, an important transcription factor associated with testicular differentiation, is conserved among teleost, which could also be detected in ovaries. In the present study, three isoforms of Pcc-dmrt1s (Pcc-dmrt1a, Pcc-dmrt1b and Pcc-dmrt1c) resulting from alternative splicing of the dmrt1 gene were cloned and characterized in the triploid gynogenetic fish, the Pengze Crucian Carp. Their mRNA expression profiling was investigated in juvenile developmental stages, tissues of the adult fish, and the juveniles under 84.2 ng/L 17α-methyltestosterone (MT) treatments. Results showed that their putative proteins shared high identities to Dmrt1 in cyprinid fish species. Gene expression profiling in the developmental stages showed that all the three target genes had a highest/lowest expression at 56/40 days post-hatching (dph), respectively. The period of 40 dph appeared to be a key time during the process of the ovary development of Pengze Crucian Carp. The tissue distribution results indicated that Pcc-dmrt1s were predominantly expressed in hepatopancreas, brain, spleen and ovary of the female fish. MT significantly increased the mRNA expression of Pcc-dmrt1a (all 4-week exposures) and Pcc-dmrt1b (except for week 2), while repressed Pcc-dmrt1c transcripts at all exposure period except for week 2. MT extremely significant repressed cyp19a1a transcripts for 1 week. The present study indicated that MT could influence the ovary development of Pengze Crucian Carp by disturbing gene expressions of Pcc-dmrt1s and cyp19a1a. Furthermore, the present study will be of great significance to broaden the understanding of masculinizing pathway during ovary development in gynogenetic teleost.

  • molecular cloning and characterization of amh dax1 and cyp19a1a genes and their response to 17α methyltestosterone in pengze Crucian Carp
    Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2013
    Co-Authors: Lihong Wang, Yao Zheng, Yingying Zhang, Hongwei Liang, Houpeng Wang, Fang Qin, Shaozhen Liu, Zaizhao Wang
    Abstract:

    The proteins encoded by amh, dax1 and cyp19a1a play important roles in gonad differentiation. Their functions have been far less studied in teleosts. In this study, the full-length cDNAs of amh, dax1 and cyp19a1a were cloned and characterized in a triploid gynogenic fish, the Pengze Crucian Carp. Their expression profilings in juvenile development, adult tissues and juveniles exposed to 100 ng/L 17α-methyltestosterone (MT) were investigated. Results showed that their putative proteins shared high identities to their counterparts in cyprinid fish species, respectively. The tissue distribution results indicated that amh and cyp19a1a were predominantly expressed in the ovary and dax1 was dominantly expressed in the liver. Gene profiling in the developmental stages showed that all the three target genes had a consistent highest expression at 48 days post hatching (dph). The period of 48 dph appeared to be a key time during the process of the gonad development of Pengze Crucian Carp. 100 ng/L MT significantly increased the mRNA expression of amh at 2- and 4-week exposures and enhanced dax1 and cyp19a1a at 6-week exposure. The present study indicated that MT could influence the gonad development in Pengze Crucian Carp by disturbing sex-differentiation associated gene expression. Furthermore, the present study will be of great significance to broaden the understanding of molecular mechanisms of the physiological processes of reproduction in fish.

  • molecular cloning and characterization of cat gpx1 and cu zn sod genes in pengze Crucian Carp carassius auratus var pengze and antioxidant enzyme modulation induced by hexavalent chromium in juveniles
    Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2013
    Co-Authors: Yao Zheng, Yingying Zhang, Hongwei Liang, Fang Qin, Shaozhen Liu, Linhu Zou, Jiejie Sun, Zaizhao Wang
    Abstract:

    Hexavalent chromium (Cr(6+)) is a common pollutant transient metal with high toxicity in the environment. The toxicological effects partly result from oxidative damage due to the production of excessive reactive oxygen species (ROS) in the reductive process of Cr(6+). To explore the influence of ROS induced directly by Cr(6+) on the oxidative stress generation and antioxidant system, the full length cDNAs of antioxidant-related genes cat, gpx1 and Cu/Zn-sod were successfully acquired from pengze Crucian Carp first and analyzed. Furthermore, the mRNA expression of the antioxidant genes encompassing catalase (cat), copper/zinc superoxide dismutase (Cu/Zn-sod) and glutathione peroxidase (gpx1), antioxidant enzyme activities of CAT, SOD, and GPx and total protein content were further studied in the gill, intestine and liver of pengze Crucian Carp (Carassius auratus var. Pengze) juveniles upon acute exposure to Cr(6+) at concentrations of 0.1, 1.0, 10 and 100 mg/L for 4 days. Differential significant changes of the antioxidant enzymes and gene expression were observed in different tissues. The findings contribute to better understanding the antioxidant mechanisms induced by Cr(6+) and selecting the organic-specific sensitive biomarkers to monitor the safety of the aquatic ecosystem.

Yun Liu - One of the best experts on this subject based on the ideXlab platform.

  • evidence for recombination of mitochondrial dna in triploid Crucian Carp
    Genetics, 2006
    Co-Authors: Xing Hong Guo, Shao Jun Liu, Yun Liu
    Abstract:

    In this study, we report the complete mitochondrial DNA (mtDNA) sequences of the allotetraploid and triploid Crucian Carp and compare the complete mtDNA sequences between the triploid Crucian Carp and its female parent Japanese Crucian Carp and between the triploid Crucian Carp and its male parent allotetraploid. Our results indicate that the complete mtDNA nucleotide identity (98%) between the triploid Crucian Carp and its male parent allotetraploid was higher than that (93%) between the triploid Crucian Carp and its female parent Japanese Crucian Carp. Moreover, the presence of a pattern of identity and difference at synonymous sites of mitochondrial genomes between the triploid Crucian Carp and its parents provides direct evidence that triploid Crucian Carp possessed the recombination mtDNA fragment (12,759 bp) derived from the paternal fish. These results suggest that mtDNA recombination was derived from the fusion of the maternal and paternal mtDNAs. Compared with the haploid egg with one set of genome from the Japanese Crucian Carp, the diploid sperm with two sets of genomes from the allotetraploid could more easily make its mtDNA fuse with the mtDNA of the haploid egg. In addition, the triple hybrid nature of the triploid Crucian Carp probably allowed its better mtDNA recombination. In summary, our results provide the first evidence of mtDNA combination in polyploid fish.

  • production of gynogenetic progeny from allotetraploid hybrids red Crucian Carp common Carp
    Aquaculture, 2004
    Co-Authors: Shao Jun Liu, Yuandong Sun, Chun Zhang, Kaikun Luo, Yun Liu
    Abstract:

    Abstract Following activation by UV-irradiated sperm, diploid eggs of the allotetraploid hybrids (red Crucian Carp ♀×common Carp ♂) developed into normal live gynogens. Cold-shocking these activated diploid eggs failed to induce the expected tetraploidy in them. All these gynogenetic progenies, generated with or without the cold shock, were female diploids with 100 chromosomes, indicating the XXXX genotype of the tetraploid females. The gynogenetic females matured at the age of 2+ suggesting delayed maturity, in comparison to the diploid females of the red Crucian Carp. Thirty percent of these gynogens were fertile with normal ovary and mature eggs. These gynogens were not morphologically distinguishable from the F2 hybrids. Like the diploid F2 hybrids, these diploid gynogens produced diploid eggs, for these eggs developed into triploids with 150 chromosomes, when crossed with red Crucian Carp. Without the treatment for doubling the chromosome number, the diploid eggs, produced by the F1 gynogens, developed into the F2 gynogens following activation by UV-irradiated sperm. Production of these diploid eggs from the diploid gynogens may have resulted from the pre-meiotic endoreduplication of chromosomes. For aquaculture, these diploid eggs remain an important gamete source for the production of tetraploids and triploids, and establishment of diploid gynogenetic hybrid line.

  • the formation of tetraploid stocks of red Crucian Carp common Carp hybrids as an effect of interspecific hybridization
    Aquaculture, 2001
    Co-Authors: Shao Jun Liu, Yun Liu, Gongjiang Zhou, Xuanjie Zhang, Chen Luo, Hao Feng, Guihua Zhu, Hui Yang
    Abstract:

    Abstract F 3 –F 8 hybrids of red Crucian Carp ( Carassius auratus red var.) (♀)×common Carp ( Cyprinus Carpio L.) (♂) were found to be allotetraploids by examining the numbers and karyotypes of chromosomes, the DNA content of red blood cells, and the mean nuclear erythrocyte volumes. The chromosome numbers of F 3 –F 8 were 4 n =200. The chromosome numbers of two types of triploids produced by mating F 3 –F 8 (♂), respectively, with diploid Japanese Crucian Carp ( C. auratus cuvieri T. et S.) (♀) and Xingguo red Carp (♀) were 3 n =150. The mean DNA content of F 3 and the triploid are, respectively, two times and 1.5 times of that of diploid Japanese Crucian Carp. F 3 hybrids had mean erythrocyte nuclear volumes about two times larger than diploid Japanese Crucian Carp. The hybrids F 3 –F 8 were fertile. It is easy for F 3 –F 8 to produce their tetraploid offspring. The triploids were sterile. Based on the analysis of karyotype and the intermediate appearance with two pairs of small bases of barbels, F 3 –F 8 hybrids were proved to be allotetraploids with two chromosome sets of red Crucian Carp and two chromosome sets of common Carp. It is concluded that the females and males of F 2 hybrids were able to produce, respectively, diploid eggs and diploid spermatozoa and they fertilized to form tetraploid fish.