[Show abstract][Hide abstract] ABSTRACT: Fish genetic breeding is a process that remolds heritable traits to obtain neotype and improved varieties. For the purpose of genetic improvement, researchers can select for desirable genetic traits, integrate a suite of traits from different donors, or alter the innate genetic traits of a species. These improved varieties have, in many cases, facilitated the development of the aquaculture industry by lowering costs and increasing both quality and yield. In this review, we present the pertinent literatures and summarize the biological bases and application of selection breeding technologies (containing traditional selective breeding, molecular marker-assisted breeding, genome-wide selective breeding and breeding by controlling single-sex groups), integration breeding technologies (containing cross breeding, nuclear transplantation, germline stem cells and germ cells transplantation, artificial gynogenesis, artificial androgenesis and polyploid breeding) and modification breeding technologies (represented by transgenic breeding) in fish genetic breeding. Additionally, we discuss the progress our laboratory has made in the field of chromosomal ploidy breeding of fish, including distant hybridization, gynogenesis, and androgenesis. Finally, we systematically summarize the research status and known problems associated with each technology.
[Show abstract][Hide abstract] ABSTRACT: Diploid natural gynogenetic goldfish (2nGRCG), triploid hybrids (3nRB) and tetraploid hybrids (4nRB) are generated by distant hybridization of red common goldfish (RCG, Carassius auratus red var.) and blunt snout bream (BSB, Megalobrama amblycephala). In the present study, we obtained the complete mitochondrial DNA (mtDNA) sequences of the hybrid offspring and compared them with the homologous sequences of RCG and BSB. All mtDNA sequences of these hybrids were 16,580bp in length, and the genes number, size, and order were quite similar to that of RCG. Genetic analysis revealed that the mtDNA sequences of these hybrids had high similarity (>99%) and low divergence (<2%) to their maternal RCG, yet lower similarities (84%) and higher divergences (16%) to their paternal BSB. The phylogenetic analysis also showed that the sequences of 2nGRCG, 3nRB and 4nRB were clustered with RCG rather than with BSB. These results indicate that the mitochondrial genomes of 2nGRCG, 3nRB and 4nRB remain maternally inherited after hybridization and polyploidization. Moreover, clade separation of hybrid offspring from their BSB in the phylogenetic tree implies that phylogenetic analysis of mtDNA is incomplete for elucidating the true relationships between different species, particularly when they have undergone hybridization or allopolyploidization. Our study provides significant information for both evolution and genetic studies of mtDNA for hybrid species and allopolyploidization species.
Current Molecular Medicine 12/2014; · 3.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An allotetraploid hybrid lineage derived from the distant hybridization of red crucian carp (Carassius auratus red var., ♀, 2n =100) × common carp (Cyprinus carpio L., ♂, 2n =100) was investigated for its mitochondrial and nuclear genome inheritance patterns. Based on liver transcriptomic data for this hybrid, red crucian carp, and common carp, we identified 94, 136, and 86 contigs corresponding to 41, 46, and 37 mitochondrial respiratory chain nuclear genes, respectively. Mitochondrial respiratory chain nuclear gene sequences from red crucian carp and common carp were both detected in the allotetraploid hybrid, indicating that both parental nuclear genomes had participated in the synthesis of mitochondrial respiratory protein complexes in the hybrid. For mitochondrial respiratory related genes, high sequence similarity (>90%) and a low nucleotide divergence rate (<0.2) between red crucian carp and common carp could be a critical factor allowing cooperation of the three genomes (red crucian carp mitochondrial genome, red crucian and common carp nuclear genomes) in the hybrid lineage. Interestingly, gene duplication events were identified in the allotetraploid hybrid, red crucian and common carp, as confirmed by analysis of orthologous gene trees for these fish. Our findings provide valuable information with which to study cooperation between the nuclear and mitochondrial genomes of other hybrids, and will provide basic genetic information of relevance to mitochondrial-related diseases in humans and animals.
Current Molecular Medicine 12/2014; · 3.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The establishment of the tetraploid organism is difficult, however, is useful in genetics and breeding. In the present study, we have artificially established an autotetraploid fish line (F2-F8) derived from the distant hybridization of Carassius auratus red var. (RR, 2n=100) (female) × Megalobrama amblycephala (BB, 2n=48) (male). The autotetraploid line (F2-F8) possess four sets of chromosomes from red crucian carp (RRRR, 4n=200), and produce diploid ova and diploid sperm, which maintains the formation of the autotetraploid line. The F2 of the autotetraploid fish resulted from the fertilization of the autodiploidy diploid eggs and diploid sperm from the females and males of F1 hybrids (RRBB, 4n=148), which perform abnormal chromosome behavior during meiosis that is revealed by the experiments of gynogenesis and backcrossing. It is the first report about the establishment of the autotetraploid fish line derived from distant hybridization. The autotetraploid fish line provides an important gamete source for the production of triploids and tetraploids. The autotetraploid fish line also provides an ideal system to investigate the poorly understood mechanisms that drive diploidization in autotetraploids, and to study the hybrid progenies' characteristics including their innovation of new traits, promoting diversity of traits, and facilitating adaptation etc.
Biology of Reproduction 08/2014; · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Distant hybridization refers to crosses between two different species or higher-ranking taxa that enables interspecific genome transfer and leads to changes in phenotypes and genotypes of the resulting progeny. If progeny derived from distant hybridization are bisexual and fertile, they can form a hybrid lineage through self-mating, with major implications for evolutionary biology, genetics, and breeding. Here, we review and summarize the published literature, and present our results on fish distant hybridization. Relevant problems involving distant hybridization between orders, families, subfamilies, genera, and species of animals are introduced and discussed, with an additional focus on fish distant hybrid lineages, genetic variation, patterns, and applications. Our review serves as a useful reference for evolutionary biology research and animal genetic breeding.
Science China. Life sciences 08/2014; · 1.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Distant hybridization can generate transgressive hybrid phenotypes that lead to the formation of new populations or species with increased genetic variation. In this study, we produced an experimental hybrid goldfish (EG) by distant crossing of red crucian carp (Carassius auratus) x common carp (Cyprinus carpio) followed by gynogenesis.
We evaluated the phenotype, ploidy level, gonadal structure, and 5S rDNA of the EG. Diploid EG possessed a high level of genetic variation, which was stably inherited. In particular, the EG combined transgressive phenotypes, including a forked tail and shortened caudal peduncle, traits that are present in common goldfish. The EG and common goldfish share a number of morphological and genetic similarities.
Using the EG, we provide new evidence that goldfish originated from hybridization of red crucian carp x common carp.
[Show abstract][Hide abstract] ABSTRACT: Increasing piRNAs provide RNA-interference pathways to regulate transposons and gene expression in germline cells. We demonstrate that Piwi transcripts are exclusively expressed in adult testes and ovaries in teleosts, with triploids showing the highest Piwi expression in the ovaries. Studies in vivo and in vitro showed that hCG and E2 treatment suppressed Piwi expression. We further cloned 200 small RNAs in the three kinds of fish. Seven piRNAs were obtained from all the three different ploidy fishes. During ovulation, five piRNAs showed significantly higher expression in the ovaries of sterile triploids than fertile diploids and tetraploids. Furthermore, E2 suppressed the expression of the six piRNAs at different levels in vivo and in vitro. The present study bridges the gap between the HPG axis and Piwi-piRNA pathway by suggesting that a dysfunctional HPG axis abrogated the piRNA suppression in triploid fish.
Molecular and Cellular Endocrinology 12/2013; · 4.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mitochondria are sub-cellular organelles responsible for producing the majority of cellular energy through the process of oxidative phosphorylation (OXPHOS), and are found in nearly all eukaryotic cells. Mitochondria have a unique genetic system, mitochondrial DNA (mtDNA), which is a small, self-replicating and diverse genome. In the past 30 years, mtDNA has made significant contribution to molecular ecology and phylogeography. Mitochondria also represent a unique system of mitochondrial-nuclear genomic cooperation. Additionally, mitochondrial dysfunction can be fatal. In this paper, we review several aspects of mitochondria, including evolution and the origin of mitochondria, energy supply and the central role of mitochondria in apoptosis, and mitochondrial dysfunction. It is shown that mitochondria play a critical role in many aspects of life.
Current Molecular Medicine 11/2013; · 3.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study we used both cytogenetics (measurement of DNA content, detection of chromosome number, observation of gonadal development)and molecular genetics(microsatellite analysis)to analyze the biological characteristics of gynogenetic M. amblycephala, which werecreatedthrough gynogenesis induced via UV-irradiated E. ilishaeformis spermatozoa to fertilize M. amblycephala eggs. The maternal genome was duplicated by cold shock in 0~4℃ cold water to form a population of M. amblycephala with 48 chromosomes whose DNA content was identical to the diploid maternal parent. Morphologically, this group of gynogenetic M. amblycephala was similar to the control group. All gynogenetic M. amblycephala were female, and no males were found in any of the examined gynogenetic M. amblycephala, providing cytogenetic evidence that our gynogenetic M. amblycephala are type XY. At the same time, microsatellite analysis showed that 63 alleles were amplified in the three test groups of gynogenetic M. amblycephala. Overall, the population of gynogenetic M. amblycephala observed heterozygosity average, and the expected average was significantly lower than the parental averages, demonstrating that after generation gynogenesis the gene homozygosity of M. amblycephala was significantly higher than the ordinary bream and E. ilishaeformis, making it a pure line. The genetic proximity of gynogenetic M. amblycephala to M. amblycephala demonstrates that gynogenesis passes on maternal DNA. Gynogenetic groups developed in this study may provide good genetic material for future breeding projects of M. amblycephala.
[Show abstract][Hide abstract] ABSTRACT: Hybridization and polyploidization may lead to divergence in adaptation and boost speciation in angiosperms and some lower animals. Epigenetic change plays a significant role in the formation and adaptation of polyploidy. Studies of the effects of methylation on genomic recombination and gene expression in allopolyploid plants have achieved good progress. However, relevant advances in polyploid animals have been relatively slower. In the present study, we used the bisexual, fertile, genetically stable allotetraploid generated by hybridization of red var. and L. to investigate cytosine methylation level using methylation-sensitive amplification polymorphism (MSAP) analysis. We observed 38.31% of the methylation changes in the allotetraploid compared with the parents at 355 randomly selected CCGG sites. In terms of methylation status, these results indicate that the level of methylation modification in the allotetraploid may have increased relative to that in the parents. We also found that the major methylation changes were hypermethylation on some genomic fragments and genes related to metabolism or cell cycle regulation. These results provide circumstantial evidence that DNA methylation might be related to the gene expression and phenotype variation in allotetraploid hybrids. Our study partly fulfils the need for epigenetic research in polyploid animals, and provides evidence for the epigenetic regulation of allopolyploids.
PLoS ONE 02/2013; 8(2):e56409. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Growth hormone (GH), growth hormone receptor (GHR) and insulin-like growth factor 1 (IGF-1) are pivotal signaling factors of the GH/IGF axis, which plays a crucial role in regulating growth in vertebrates. In this study, GH, GHR and IGF-1 cDNAs were cloned from triploid and tetraploid crucian carp. In addition, mRNA expression levels were characterized in diploid red crucian carp, triploids and tetraploids. Reverse transcriptase PCR indicated that GH genes were only expressed in the pituitary, while GHR and IGF-1 were widely expressed in all tested tissues. Real-time PCR study of different seasonal profiles showed that triploids had significantly higher expression of the studied genes during both the prespawning and the spawning season. Although different temperatures (22, 26 and 30°C) showed no significant effects on GH, GHR and IGF-1 mRNA expression in either diploids or triploids, triploids had higher expression levels than diploids at each temperature. After 1 week of fasting, the expression of all studied genes was reduced in both diploids and triploids, while the expressions levels were higher in triploids than in diploids. These results suggest that the elevated expression of GH/IGF axis genes in triploids plays a crucial role in the faster growth rate of triploids.
General and Comparative Endocrinology 06/2012; 178(2):291-300. · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: The relationship between recurrent major depression (MD) in women and suicidality is complex. We investigated the extent to which patients who suffered with various forms of suicidal symptomatology can be distinguished from those subjects without such symptoms.Method
We examined the clinical features of the worst episode in 1970 Han Chinese women with recurrent DSM-IV MD between the ages of 30 and 60 years from across China. Student's t tests, and logistic and multiple logistic regression models were used to determine the association between suicidality and other clinical features of MD. RESULTS: Suicidal symptomatology is significantly associated with a more severe form of MD, as indexed by both the number of episodes and number of MD symptoms. Patients reporting suicidal thoughts, plans or attempts experienced a significantly greater number of stressful life events. The depressive symptom most strongly associated with lifetime suicide attempt was feelings of worthlessness (odds ratio 4.25, 95% confidence interval 2.9-6.3). Excessive guilt, diminished concentration and impaired decision-making were also significantly associated with a suicide attempt. CONCLUSIONS: This study contributes to the existing literature on risk factors for suicidal symptomatology in depressed women. Identifying specific depressive symptoms and co-morbid psychiatric disorders may help improve the clinical assessment of suicide risk in depressed patients. These findings could be helpful in identifying those who need more intense treatment strategies in order to prevent suicide.
Psychological Medicine 04/2012; · 5.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Piwi proteins are required for germline maintenance and gonad development. In this study, the cDNAs encoding Piwil1 and Piwil2 were cloned and sequenced from the common carp. The full-length cDNA of Piwil1 and Piwil2 were 3114 and 3421bp, encoding 858 and 1034 amino acids including PAZ domain and PIWI domain, respectively. In addition, the Piwil1 and Piwil2 proteins shared high homology with other teleosts. Reverse transcriptase PCR revealed that the Piwi mRNAs were exclusively expressed in adult testes and ovaries. Using real-time PCR, expression study of different developmental profiles showed that Piwil1 and Piwil2 were down-regulated during pre-ovulation. Further, human chorionic gonadotropin treatment in ovaries (in vivo) and in cultured ovaries cells (in vitro) resulted in down-regulation of Piwi RNAs. These results suggest that the decreased expression which was regulated by hormone plays a crucial role during ovarian differentiation and development.
General and Comparative Endocrinology 02/2012; 176(2):126-31. · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Crucian carp (abbreviated CC) belongs to the genus of Carassius within the family of Cyprinidae. It has been one of the most important freshwater species for Chinese aquaculture and is especially abundant in the Dongting water system of Hunan province. CC used to be considered as all diploid forms. However, coexistence of diploid (abbreviated 2nCC), triploid (abbreviated 3nCC) and tetraploid crucian carp (abbreviated 4nCC) population of the Dongting water system was first found by our recently researches.
We examined the ploidy level and compared biological characteristics in different ploidy CC. In reproductive mode, 2nCC was bisexual generative and 4nCC generated all-female offspring by gynogenesis. However, 3nCC generated progenies in two different ways. 3nCC produced bisexual triploid offspring fertilized with 3nCC spermatozoa, while it produced all-female triploid offspring by gynogenesis when its ova were activated by heterogenous spermatozoa. The complete mitochondrial DNA of three different ploidy fishes was sequenced and analyzed, suggesting no significant differences. Interestingly, microchromosomes were found only in 3nCC, which were concluded to be the result of hybridization. Allogenetic DNA fragments of Sox genes were obtained in 3nCC and 4nCC, which were absent in 2nCC. Phylogenetics analysis based on Sox4 gene indicated 3nCC and 4nCC formed a separate group from 2nCC.
In summary, this is the first report of the co-existence of three types of different ploidy crucian carps in natural waters in China. It was proved that the coexistence of different ploidy CC was reproductively maintained. We further hypothesized that 3nCC and 4nCC were allopolyploids that resulted from hybridization. The different ploidy CC population we obtained in this study possesses great significance for the study of polyploidization and the evolution of vertebrates.
[Show abstract][Hide abstract] ABSTRACT: Grass carp (Ctenopharyngodon idellus) eggs were activated by UV-irradiated diploid sperm of allotetraploid hybrids derived from red crucian carp (♀) × common carp (♂) and then duplicated by cold shock in 4-6°C water for 10-12 min. Different cold shock initiation times resulted in two types of diploid gynogenetic grass carp: meiotic gynogenetic (meiG) and mitotic gynogenetic (mitG). Over a 5-year period, a total of 17,170 meiG and 1,080 mitG fry were produced and 6,862 meiG and 372 mitG grass carp survived. The gynogenetic fish were confirmed by morphological characteristics, chromosome examination, and microsatellite DNA analysis. The morphological traits of the gynogenetic grass carp were similar to those of wild diploid grass carp. Normal gynogenetic fish were identified as diploid with 48 chromosomes by chromosomal metaphases examination, while nonviable abnormal embryos were detected as haploid with 24 chromosomes. Microsatellite DNA analysis indicated that after one generation of gynogenesis, the genetic purity of meiG and mitG grass carp was significantly increased over that of wild grass carp. In addition, both meiG and mitG grass carp groups were 100% female, and 88% of these showed normal ovary development. Thus, the sex determination mechanism in female grass carp was homogamety. The ability to establish pure all-female groups of meiG and mitG grass carp should be a valuable contribution to both fish genetics and grass carp breeding.
[Show abstract][Hide abstract] ABSTRACT: In many species of aquaculture importance, all-female and sterile populations possess superior productivity due to faster growth and a relatively homogenous size of individuals. However, the production of all-female and sterile fish in a large scale for aquaculture is a challenge in practice, because treatments necessary for gynogenesis induction usually cause massive embryonic and larval mortality, and the number of induced gynogens is too small for their direct use in aquaculture. Here we report the massive production of all-female triploid crucian carp by combining artificial gynogenesis, sex reversal and diploid-tetraploid hybridization. Previously, we have obtained an allotetraploid carp population (4n = 200) by hybridization between red crucian carp (Carassius auratus red var; ♀) and common carp (Cyprinus carpio; ♂). We induced all-female diploid gynogens of the Japanese crucian carp (Carassius cuvieri; 2n = 100). We also generated male diploid gynogens of the same species treated gynogenetic fry with 17-α-methyltestosterone, leading to the production of sex-revered gynogenetic males. Finally, these males were used to cross with the female diploid Japanese crucian carp gynogens and the allotetraploid females, resulting in the production of fertile all-female diploid Japanese crucian carp (2n=100) and sterile all-female triploid hybrids (3n = 150), respectively. Therefore, diploid crucian carp gynogenetic females and sex-reversed male together with an allotetraploid line provide an opportunity to produce all-female triploid populations in a large scale to meet demands in aquaculture industry.
International journal of biological sciences 01/2011; 7(4):487-95. · 4.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The occurrence of polyploidy, or whole genome duplication, can result in instantaneous speciation. Because new polyploids
are immediately reproductively isolated from their non-polyploid congeners, polyploidization has played an important role
in the diversification of flowering plants and some vertebrates. Newly formed polyploids must respond to this instantaneous
genomic change, which resembles “genome shock” syndrome to survive and reproduce successfully. Epigenetic changes, which do
not cause changes to the sequence of DNA, can significantly contribute to the survival of and ultimately to the evolutionary
success of new polyploids. Epigenetic regulation, both transcriptional and post-transcriptional, entails changes in DNA methylation,
gene status and/or nucleolus dominance. These changes provide effective and flexible ways for a new polyploid to respond quickly
to the enormous change in genetic material, to survive and potentially reproduce. We examine and assess certain epigenetic
phenomena and possible pathways that may facilitate the evolutionary success of polyploid organisms.
Keywordspolyploidization–epigenetics–DNA methylation–gene status–nucleolus dominance
Chinese Science Bulletin 01/2011; 56(3):245-252. · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gynogenesis was induced by using UV-irradiated spermatozoa of blunt snout bream Megalobrama amblycephala to activate eggs of common carp Cyprinus carpio. The maternal genome was then duplicated by cold shock in 0 to 4° C cold water to retain the second polar body. Two kinds of fry, normal fry and abnormal tortuous fry, were hatched. Their DNA content was measured by flow cytometry. The normal fry were identified as diploid, representing the successful gynogenesis in C. carpio whereas the abnormal tortuous fry were haploid. Ten microsatellite loci were used to study the genetic diversity among C. carpio, diploid gynogenetic C. carpio and unduplicated haploid tortuous fry. The results indicated that the genetic homozygosity of gynogenetic C. carpio was significantly higher than that of C. carpio. The genetic homozygosity of the haploid C. carpio was intermediate between that of gynogenetic C. carpio and C. carpio. It might be easier for the allogenetic DNA fragments to be integrated into the haploid genome than into diploid gynogenetic genome.
Journal of Fish Biology 01/2011; 78(1):150-65. · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The gonadotropin-releasing hormone (GnRH) and the gonadotropin hormone (GTH) play crucial roles in regulating the gonadal development of the vertebrate. In this study, the Gnrh2, Fshβ and Lhβ cDNAs were cloned and characterized in red crucian carp, triploids and tetraploids, and their phylogenetic relations were comparatively analyzed. All the Gnrh2 cDNAs in different ploidy fishes encoded proteins of 86 amino acids, which consisted of a signal peptide, a GnRH2 decapeptide and a GnRH-associated peptide (GAP) linked by a proteolytic cleavage site (Gly-Lys-Arg). The GnRH2 decapeptide and proteolytic cleavage site were absolutely consistent among the three ploidy fishes, but the differences in signal peptide and GAP between diploids and tetraploids were fewer than those between diploids and triploids. It was presumed that the red crucian carp was the original maternal parent of tetraploids, so they had closer relationship. In addition, the Fshβ and Lhβ cDNAs of these three fishes encoded proteins of 130 and 140 amino acids, respectively. Compared with the molecules of other teleosts, the cysteine residues and potential glycosylation sites of Lhβ in these three fishes are fully conserved. However, most teleosts of Fshβ had 12 cysteine residues, while those of these three fishes were 13, and 12 of which might form six conserved disulfide bridges by utilizing the cleavage sites between the first and the second cysteine residues. Moreover, the lack of the second glycosylation site in Fshβ of these three fishes might influence the special structure and biological activities. On the other hand, the phylogenic tree analyses revealed that Gnrh2, Fshβ and Lhβ had similar phylogeny relationships among the cyprinids, which indicated that they were conserved in molecular structure and function during the evolution.
Progress in Natural Science 11/2009; 19(11):1569-1579. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gonadotropin-releasing hormone (GnRH), gonadotropin hormone (GTH), and gonadotropin hormone receptor (GTHR) are the pivotal signal molecules of the hypothalamic-pituitary-gonad (HPG) axis, which plays a crucial role in regulating gonadal development in vertebrate. In this study, we comparatively analyze the expression characteristics of Gnrh2, Gthbeta, and Gthr in red crucian carp diploids, triploids, and allotetraploids. The expression patterns of these genes are similar in the three fish ploidy types: the Gnrh2 gene is expressed in midbrains, pituitaries, and gonads; the Gthbeta gene is expressed in pituitaries; the Gthr gene is mainly expressed in gonads. These results indicate that the three genes participate in the regulation of gonadal development. By real-time polymerase chain reaction and in situ hybridization, we find that, among these three fish ploidy types, the expression level of Gthr in the gonads of triploids is lower than those of diploids and tetraploids; this weakens the combination of GTHR with GTH released from the pituitary and leads to the sterility of triploids, since the gonad cannot produce enough sex steroids. In addition, the low expression of Gthr in triploids may affect the down-regulation of Gthbeta, which then affects the down-regulation of Gnrh2; hence, the expression levels of Gnrh2 and Gthbeta genes in triploids are the highest after the breeding season. In conclusion, the differential expression of Gnrh2, Gthbeta, and Gthr in triploids and tetraploids is related to their sterility and bisexual fertility, respectively.
Cell and Tissue Research 09/2009; 338(1):151-9. · 3.33 Impact Factor