Gynogenetic Offspring Research Articles

Activin Signaling Pathway Specialization During Embryonic and Skeletal Muscle Development in Rainbow Trout (Oncorhynchus mykiss).

Activin signaling is essential for proper embryonic, skeletal muscle, and reproductive development. Duplication of the pathway in teleost fish has enabled diversification of gene function across the pathway but how gene duplication influences the function of activin signaling in non-mammalian species is poorly understood. Full characterization of activin receptor signaling pathway expression was performed across embryonic development and during early skeletal muscle growth in rainbow trout (RBT, Oncorhynchus mykiss). Rainbow trout are a model salmonid species that have undergone two additional rounds of whole genome duplication. A small number of genes were expressed early in development and most genes increased expression throughout development. There was limited expression of activin Ab in RBT embryos despite these genes exhibiting significantly elevated expression in post-hatch skeletal muscle. CRISPR editing of the activin Aa1 ohnolog and subsequent production of meiotic gynogenetic offspring revealed that biallelic disruption of activin Aa1 did not result in developmental defects, as occurs with knockout of activin A in mammals. The majority of gynogenetic offspring exhibited homozygous activin Aa1 genotypes (wild type, in-frame, or frameshift) derived from the mosaic founder female. The research identifies mechanisms of specialization among the duplicated activin ohnologs across embryonic development and during periods of high muscle growth in larval and juvenile fish. The knowledge gained provides insights into potential viable gene-targeting approaches for engineering the activin receptor signaling pathway and establishes the feasibility of employing meiotic gynogenesis as a tool for producing homozygous F1 genome-edited fish for species with long-generation times, such as salmonids.

The first case of gynogenesis induced by cold- and heat-shock treatment in Thamnaconus modestus

Gynogenesis is an effective technique for establishing homogeneous lines and confirming potential chromosomal mechanisms of sex determination in fish. The objective of this study was to induce meiotic gynogenesis in Thamnaconus modestus through the application of cold- or heat-shock treatment, with the ultimate goal of establishing a foundational population to enhance breeding outcomes. Firstly, we obtained the optimal dosage of ultraviolet irradiation (55 mJ/cm2) required to render the sperm genome inactive while still allowing egg activation without any contribution of genetic material to the progeny. After fertilization with the inactivated sperm, diploidization was achieved through either cold-shock (12 °C for 45 min) or heat-shock (38 °C for 1 min), which suppressed the extrusion of the second polar body. Gynogenetic offspring were confirmed through genotyping using 12 microsatellite markers with parental specificity. The heterozygosity of meiotic gynogenesis group decreased by 35.14% when analyzed using SNP markers through whole genome resequencing technique, compared with the wild populations. Overall, the meiotic gynogenetic families were successfully induced, and this is the first protocol described for the induction of gynogenesis in T. modestus, which establishing a complete method of meiotic gynogenesis induction. The procedure described herein may be used to produce a clonal line of fish or for the breeding of improved varieties of T. modestus and other related species.

Comparative analysis of the texture, composition, antioxidant capacity and nutrients of natural gynogenesis blunt snout bream and its parent muscle

Gynogenesis, as a special method of distant hybridization, can be used to accelerate the formation of breeding lines such as fish varieties and populations, and cultivate lines or varieties with higher dominant traits. While, there are few reports on the study of gynogenesis between trans order species in freshwater fish. Even the meat quality comparison between the gynogenetic offspring obtained above and their parents is rarely studied. In order to understand whether the meat quality of naturally gynogenetic blunt snout bream (GBSB) is better than that of its parents (blunt snout bream♀ and Chinese perch♂), we analyzed the texture, composition, antioxidant capacity and nutrients of natural gynogenesis blunt snout bream and its parent muscle. In the muscle of texture characteristics of hardness, springiness, gumminess and chewiness, natural GBSB were better than those of the normal BSB. Muscle fiber size of GBSB is between the maternal and the paternal fish. Compared with the maternal parent, the natural GBSB had higher antioxidant enzyme activities (CAT, SOD and GSH) and higher mineral element (Na, Mg, Ca, P and Zn) contents. In muscle nutrients, the gynogenetic offspring also had more delicious amino acids (Asp, Glu, Gly, Ala, Tyr and Phe) and fatty acids than the maternal parents. Collectively, through distant hybridization between common BSB and Chinese perch (CP), a high-quality gynogenetic fish with more nutrition and stronger muscle performance than maternal fish was obtained. The above results not only provide evidence for the hybridization origin of gynogenetic fish, but also provide new ideas for the innovation of new species.

Induction of gynogenesis with ultra-violet irradiated Koi carp (Cyprinus carpio haematopterus) sperm demonstrates the XX/XY sex determination system in Opsariichthys bidens

Opsariichthys bidens (Chinese hooksnout carp) is a small stream fish with high economic value. As the males of this species grow faster than females, it follows that mono-sex breeding has significant potential for commercial production. However, little is known about the sex determination system in O. bidens, this is the key process that is used to develop mono-sex breeding in fish. In the present study, we induced gynogenesis by fertilizing O.bidens eggs with ultra-violet (UV)- inactivated Cyprinus carpio haematopterus (Koi carp) sperm followed by cold shock treatment. Results showed that the optimal induction conditions was 25 min duration of cold shock treatment at 2 min post fertilization (mpf), the highest fertilization rate and hatching rate for gynogenic embryos were 68.24 ± 3.75% and 12.54 ± 1.59%, respectively. Embryos derived from gynogenesis developed normally, but the hybrid embryos failed (created with non-UV-inactivated Koi carp sperm and O.bidens eggs). Genetic analysis demonstrated only maternal inheritance in the gynogenetic offspring. Histological analysis further showed that the gonads of all gynogenetic fish were ovaries, thus suggesting that the sex-determining system of O. bidens is male heterogametic (XX-XY). The present study is the first to establish a procedure for inducing gynogenesis, we also identified the sex determination system (SD) of O. bidens, that will be possible to produce only male.

Induction of meiotic gynogenesis in Lanzhou catfish ( Silurus lanzhouensis ) with heterologous sperm and evidence for female homogamety

As a critical factor in the sustainability of fisheries, gynogenesis can be used to provide a shortcut for the genetic improvement of the endangered and degraded germplasm resources of the important Yellow River fish Silurus lanzhouensis. In this study, ultraviolet-inactivated yellow catfish Pelteobagrus fulvidraco sperm were used to induce meiotic gynogenesis in S. lanzhouensis through cold shock, and the optimal conditions for the genetic inactivation of the sperm and cold shock treatment were selected. Using microsatellite markers and gonadal histology, the genetic purity and sex determination of the gynogenetic offspring of S. lanzhouensis were analysed. The optimal induction conditions were as follows: treatment with P. fulvidraco sperm with 107- µW/cm2 ultraviolet irradiation for 30 min, fertilization of S. lanzhouensis eggs for 6 min and subsequent cold shock treatment at 4–6°C for 25 min. Flow cytometry and microsatellite markers confirmed the successful induction of meiogynogenesis. The homozygosity of the gynogenetic group (0.63) was higher than that of the normal control group (0.32). The sex ratio was determined through gonad histological observations, and 100% of the offspring in the gynogenetic groups were female, strongly indicating that the sex determination system of S. lanzhouensis is the XX/XY-type. In this study, inactivated heterologous sperm were used to successfully obtain meiogynogenetic individuals of S. lanzhouensis, and the study provides an important basis for the establishment of a pure line of these endangered fish and sex-controlled breeding of S. lanzhouensis.

Induction of gynogenesis by heterogenous sperm and cold shock treatment in Epinephelus fuscoguttatus

Gynogenesis is a chromosome set manipulation technique to accelerate inbred lines used for genomics analysis and genetic breeding. Groupers are hermaphroditic fish whereby they sexually mature as females and subsequently change sex to male. Production of the homozygous inbred lines of groupers will take a prolonged period with the traditional method. This study presents the meiotic gynogenesis induction of the commercially cultured grouper Epinephelus fuscoguttatus, using a combination of ultraviolet-irradiated heterogenous sperm of E. lanceolatus and recovering second polar body by cold-shock treatment. DNA ploidy verification by flow cytometry showed that the haploid larvae exhibited abnormalities and diploids developed normally. The results indicated that UV irradiation doses at 150 ​mJ/cm2 produced 100% haploid larvae. The high percentage (52.1% ​± ​8.50%) of gynogenetic diploidy was induced by cold shock at 5–7 ​°C for 10 ​min, initiated 6 ​min after fertilization. The gynogenetic offspring presented 48 chromosomes (2n ​= ​48t) and were morphologically identical to maternal chromosomes. Cytological and morphological evidence suggested that gynogenetic individuals were successfully obtained. Histological examination revealed that the gynogens gonads could develop into ovaries. Summarily, the gynogenesis technique was very representative of creating inbred lines in groupers. The successful production of this inbred lines is of great significance in grouper genetic breeding and genomic analysis.

Distant hybridization and gynogenesis between Nile tilapia Oreochromis niloticus and Jaguar cichlid Parachromis managuensis

To investigate the distant hybridization and gynogenesis between Nile tilapia Oreochromis niloticus and Jaguar cichlid Parachromis managuensis, reciprocal crossing was first performed between the two species. No offspring, however, were viable when there were these hybridizations. Gynogenesis was induced in O. niloticus and P. managuensis using ultraviolet (UV)-irradiated spermatozoa from P. managuensis and O. niloticus, respectively. The morphology during embryonic development indicated gynogenetic offspring of both O. niloticus and the P. managuensis were normal and deformed, and the results from flow cytometric analysis indicated normal fry were diploid and deformed fry were haploid. Gynogenetic O. niloticus and P. managuensis had the same DNA content and chromosome number as their species of origin, indicating that gynogenetic individuals were produced in both species. The presence of only females for both gynogenetic P. managuensis and O. niloticus was indicative of an XX genotype in the female P. managuensis and O. niloticus. Results from studies on genetic diversity indicated the average heterozygosity of the gynogenetic diploid population of O. niloticus were less than that of the cultured population, but the genetic homozygosity of the gynogenetic diploid population of O. niloticus was greater than that of the cultured population after one generation of gynogenesis, which achieved the goal of rapidly establishing genetic homozygosity.

Fertility of females of sturgeon hybrids obtained from species with different levels of ploidy ( Acipenser ruthenus and A. dauricus ) and their cloning

Main purpose of this work is the identification of females of artificial sturgeon hybrids capable to produce unreduced oocytes. The importance of this task is due to the ability to receive clonal all-female lines. Experiments were performed on the previously obtained reciprocal hybrids of sterlet, Acipenser ruthenus (S) with ~120 chromosomes and kaluga, Acipenser dauricus (K) with ~260 chromosomes. Karyotypes of backcross hybrids of (S × K) female (obtained by crossing sterlet female with kaluga male) and sterlet male included 180 – 190 chromosomes. This means that (S × K) female produced eggs with ~125 chromosomes and its karyotype consisted of ~250 chromosomes. This number was confirmed by a comparative analysis of erythrocyte size in this female and species with different ploidy. Karyotype with ~250 chromosomes can occur in (S x K) female only as a result of fertilization of a diploid sterlet egg (120 chromosomes) with kaluga haploid sperm (~130 chromosomes). Eggs of hybrid fertile (S × K) female, inseminated with inactivated sperm of Amur sturgeon and sterlet, developed into viable gynogenetic offspring, confirmed by the analysis of five microsatellite loci in this progeny, (S x K) female, and males used for UV-inactivated sperm. These data allow us to propose a method for obtaining fertile females of sturgeon hybrids from species with different ploidy. For this, experimentally obtained diploidized eggs from diploid 120-chromosome species must be fertilized by 250–270-chromosome male. Karyotypes of backcross hybrids of (K × S) female (obtained by crossing kaluga female with sterlet male) and sterlet male included ~250 chromosomes and hybrids of this female with kaluga male had ~320 chromosomes. These results proved an ability of hybrid (K × S) female to produce unreduced eggs, resulting in triploid backcrosses. The absence of reduction during egg development is well known in clonal forms (species) of vertebrates, which are of hybrid origin, and in artificially created fish hybrids. However, this has not been reported previously for sturgeons. Insemination of eggs of (K × S) female with UV-inactivated sperm of sterlet and Amur sturgeon led to offspring generation for which the genetic identity to their mother was proved using microsatellite analysis. That is, clonal inheritance was observed. These results suggest the possibility of developing a technology to produce all-female offspring. Artificial production of clonal lines in hybrid vertebrates can be also considered as experimental reproduction of the first stages of reticular speciation in nature.

Preliminary Identification of Candidate Genes Related to Survival of Gynogenetic Rainbow Trout (Oncorhynchus mykiss) Based on Comparative Transcriptome Analysis.

Simple SummaryGynogenetic doubled haploid zygotes in fish are produced by the activation of eggs with irradiated spermatozoa, followed by the exposure of the activated eggs to the temperature or high hydrostatic pressure (HHP) shock that prevents the first cell cleavage. Variation in the survival rates of the gynogenetic embryos developing in eggs originating from different females have been reported in several studies. As eggs of different origin show altered ability for the gynogenetic development, it was tempting to assume that the ova showing such a vast difference in potential for gynogenesis may have also had different maternal gene expression profiles. To verify these hypotheses, we compared the next-generation sequencing data of the maternal mRNA collected from rainbow trout eggs showing varied ability to develop after activation with UV-irradiated spermatozoa. Eggs originating from females whose gynogenetic offspring had the highest survival showed an increased expression of 46 genes associated among others with cell survival, migration and differentiation, triglyceride metabolism, the biosynthesis of polyunsaturated fat, and early embryogenic development, 5S RNA binding, embryonic neurogenesis and tissue modelling during development as well as senescence and aging, among others. Such genes may be considered as potential candidate genes whose expression enable efficient gynogenesis in rainbow trout.In the present research, the eggs from four rainbow trout females were used to provide four groups of gynogenetic doubled haploids (DHs). The quality of the eggs from different clutches was comparable, however, interclutch differences were observed in the gynogenetic variants of the experiment and the survival of DH specimens from different groups varied from 3% to 57% during embryogenesis. Transcriptome analysis of the eggs from different females exhibited inter-individual differences in the maternal genes’ expression. Eggs originating from females whose gynogenetic offspring had the highest survival showed an increased expression of 46 genes when compared to the eggs from three other females. Eggs with the highest survival of gynogenetic embryos showed an up-regulation of genes that are associated with cell survival, migration and differentiation (tyrosine-protein kinase receptor TYRO3-like gene), triglyceride metabolism (carnitine O-palmitoyltransferase 1 gene), biosynthesis of polyunsaturated fat (3-oxoacyl-acyl-carrier-protein reductase gene), early embryogenic development (protein argonaute-3 gene, leucine-rich repeat-containing protein 3-like gene), 5S RNA binding (ribosome biogenesis regulatory protein homolog) as well as senescence and aging (telomerase reverse transcriptase, TERT gene), among others. Positive correlation between the genotypic efficiency and egg transcriptome profiles indicated that at least some of the differentially expressed genes should be considered as potential candidate genes for the efficiency of gynogenesis in rainbow trout.

Rapid Genomic and Epigenetic Alterations in Gynogenetic Carassius auratus Red Var. Derived from Distant Hybridization.

Gynogenesis is an important reproductive mode in fish and is used fairly widely in genetic breeding. Gynogenetic offspring (2n = 100, abbreviated as GRCC) were generated through the distant hybridization of Carassius auratus red var. (2n = 100, RCC) (♀) × Megalobrama amblycephala (2n = 48, BSB) (♂), in which male and female individual both had normal gonadal development. To better understand genomic and epigenetic consequences of GRCC, fluorescence in situ hybridization, amplified fragment length polymorphism, and methylation-sensitive amplification polymorphism analysis were performed on GRCC and RCC. GRCC possess two sets of RCC-derived chromosomes and one to three microchromosomes, in which 30.44% of bands inherit these patterns from red crucian carp and blunt snout bream, and 24.12% of novel bands were found by amplified fragment length polymorphism analysis. In terms of methylation, the DNA methylation level of GRCC was lower than that of their parents, and 45.29% of methylation patterns in GRCC were altered compared with their parents. GRCC show a special genetic composition in the genome, in which genome-wide changes and the adjustment of DNA methylation levels and patterns occurred. The result revealed that genetic and epigenetic changes were rapidly triggered in gynogenetic fish that were derived from distant hybridization, showing a special genetic composition in the genome. This study provides new insights into fish genetic breeding and the evolutionary patterns of the vertebrate genome.

The first case of induced gynogenesis in Neotropical fishes using the yellowtail tetra (Astyanax altiparanae) as a model organism

Gynogenesis is a chromosome manipulation technique applicable on the production of all-female populations, generation of inbred or clonal lines and identification of genetic sex determination mechanisms in fish. Therefore, the aim of this study was induce meiotic gynogenesis in Astyanax altiparanae and determine the genetic basis of sex determination. Firstly, we evaluated the best UV-irradiation dosage in order to inactivate sperm genome, preserving the capacity of egg activation without the genetic material contribution to the offspring. After the fertilization using the inactivated sperm, diplodization was achieved by heat-shock (40 °C; 2 min) by suppression of the 2nd polar body extrusion. Diploid control and gynogenetic individuals were raised until 240 days. The gynogenetic offspring were confirmed by genotyping using microsatellite markers and the sex ratio of gynogenetic progenies suggests that most data fit to a XX/XY model of sex determination. However, unexpected sex ratios were also observed and possible reasons are discussed. This was the first protocol of induced gynogenesis in a Neotropical fish and such a procedure may be used to produce clonal linage of fish and for future mass production of monosex populations in A. altiparanae and other related species.

Evidence for paternal DNA transmission to gynogenetic grass carp

BackgroundGrass carp (Ctenopharyngodon idellus, GC), as the highest-output fish in China, is economically important. The production of gynogenetic grass carp (GGC) will provide important germplasm resource for producing improved GC. At present, knowledge regarding the heterologous sperm DNA in gynogenetic offspring is little. Thus, revealing paternal DNA in GGC at the molecular level would be highly significant for fish genetic breeding.ResultIn this study, ultraviolet-treated sperm of koi carp (Cyprinus carpio haematopterus, KOC, 2n = 100), was used to activate the eggs of GC (2n = 48). Afterwards, cold shock (0–4 °C) was administered for 12 min to double the chromosomes, resulting in GGC. No significant difference (p > 0.05) was found between GGC and GC in appearance, erythrocytes size and chromosome numbers. However, at the molecular level, a specific microsatellite DNA fragment (MFW1-gynogenetic grass carp, MFW1-G) derived from the paternal parent KOC was found to be transmitted into GGC.ConclusionsFor the first time, this study provided an evidence at the molecular level that the DNA fragment derived from the paternal parent occurred in GGC. This finding is of great significance for fish genetic breeding.

Cloning in sturgeon hybrids (Acipenseridae): experimental reproduction of the first stages of reticular speciation in fish and the method of obtaining all-female offspring

Cloning in sturgeon hybrids (Acipenseridae): experimental reproduction of the first stages of reticular speciation in fish and the method of obtaining all-female offspring

Induced gynogenesis in autotetraploids derived from Carassius auratus red var. (♀) × Megalobrama amblycephala (♂)

Autotetraploids fish (4nRR) (4n = 200, AAAA) were resulted from the whole-genome duplication of Carassius auratus red var. (RCC) (2n = 100, AA). Following activation by UV-irradiated Megalobrama amblycephala (BSB) sperm, the autodiploid eggs (2n = 100, AA) of 4nRR females developed into all-female autodiploid gynogenetic offspring (G1) (2n = 100, AA) without chromosome doubling treatment, indicating an XXXX genotype of the female autotetraploids. Compared with 4nRR and RCC, G1 individuals matured after 2 years, suggesting obviously delayed maturity. Tetraploid offspring (4nRG) (4n = 200) were also produced by crossing G1 females with male autotetraploids, suggesting that G1 individuals can produce unreduced eggs (2n = 100). After activation by UV-irradiated BSB sperm, the fertilized eggs of G1 females developed into a second generation of autodiploid gynogenetic offspring (G2) (2n = 100, AA) without chromosome doubling treatment. The diploid gametes are an important gamete source for the production of polyploid fish and the establishment of a diploid gynogenetic clone line, which will be useful for genetic analyses and breeding.

Microsatellite genetic analysis of gynogenetic grass carp group and two common grass carp groups

PDF HTML阅读 XML下载 导出引用 引用提醒 雌核发育草鱼群体及两个普通草鱼群体的微卫星遗传分析 DOI: 作者: 作者单位: 山东省淡水渔业研究院, 山东省淡水水产遗传育种重点实验室, 山东 济南 250017 作者简介: 朱树人(1986-),男,博士,研究方向为水产动物遗传育种.E-mail:zhshr229@163.com 通讯作者: 中图分类号: S917 基金项目: 国家自然科学基金项目（31440090）；国家大宗淡水鱼产业技术体系济南综合试验站项目（CARS-45-43）；山东省农业良种工程项目（2014lz042）；山东省现代农业产业技术体系鱼类创新团队项目（SDAIT-14-011-01）；山东省重点研发计划项目（2018GNC110034）. Microsatellite genetic analysis of gynogenetic grass carp group and two common grass carp groups Author: Affiliation: Shandong Provincial Key Laboratory of Freshwater Genetics and Breeding, Shandong Freshwater Fisheries Research Institute, Jinan 250017, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以草鱼（）养殖群体（YZ）为母本，以紫外线灭活的鲤鱼精子激活草鱼卵子，冷休克抑制第二极体排出的方法诱导获得异精雌核发育草鱼群体（CH）。利用12对微卫星引物对YZ群体、YS （扬州广陵长江系家鱼原种场引进草鱼群体）群体、CH群体进行PCR扩增并分析，共检测出194个等位基因，其中75.8个有效等位基因。YZ群体、YS群体、CH群体的平均等位基因数依次为13.0、12.6、4.7；平均有效等位基因数依次是7.7、6.6、2.3；平均期望杂合度依次为0.87、0.82、0.56；平均多态信息含量依次为0.84、0.79、0.49。从每个个体在微卫星位点的纯合率看，YZ群体中个体的纯合度在0.00~0.33，YS群体中个体的纯合度在0.00~0.42，CH群体中个体的纯合度在0.42~0.92。这表明与YZ群体和YS群体相比，CH群体的遗传多样性显著下降，并且在每个位点的纯合率CH群体均高于普通草鱼群体，表明人工诱导减数雌核发育可加速草鱼大多数基因位点的纯合，是快速建立高纯品系的有效手段。同时，本研究筛选并利用微卫星位点组合建立了雌核发育草鱼子代不同家系及其母本亲缘关系的简易、高效鉴别技术，旨在为雌核发育草鱼标记辅助育种打下基础。 Abstract:We induced the gynogenetic offspring of the breeding grass carp (YZ) using UV-inactivated grass carp sperm and cold shock method to inhibit extrusion of the second polar body. Twelve pairs of microsatellite primers were used for amplification and genetic analysis of the YZ population and control population (YS). A total of 194 alleles were detected in the YZ and YS populations, of which 75.8 were effective alleles. The average number of alleles in the YZ, YS and CH populations was 13.0, 12.6, and 4.7, respectively; the average number of effective alleles was 7.7, 6.6, and 2.3, respectively; the average expected heterozygosities were 0.87, 0.82, and 0.56, respectively; and the average polymorphism information content was 0.84, 0.79, and 0.49, respectively. Homozygosity was analyzed for the microsatellite loci:the homozygosity of individuals in the YZ population was 0.00-0.33, the homozygosity of individuals in the YS population was 0.00-0.42, and the homozygosity of individuals in the CH population was 0.42-0.92. The results showed that the genetic diversity of the CH population was significantly lower than that of the YZ population and the YS population, and the homozygosity of the CH population at each locus was higher than that of the common grass carp groups. This suggests that artificially induced meiotic gynogenesis can accelerate the homozygosity of most grass carp gene loci and is an effective means of rapidly establishing a high purity strain. At the same time, this study screened and used microsatellite loci combinations to establish a simple and efficient identification technique for the genetic relationship among different families and their female parent, laying a foundation for the marker-assisted breeding of gynogestidium. 参考文献 相似文献 引证文献

Presence of gynogenetic males suggests a female heterogamety in sterlet Acipenser ruthenus L.

Investigation of the heterogametic sex in sterlet Acipenser ruthenus L. was performed using meiotic gynogenesis and gonadal histology. Eggs from the albino females were activated by UV irradiated sperm of wild colored males and exposed to a heat shock. The resultant fish were all albino and exhibited exclusively maternal inheritance of the microsatellite DNA markers. Cytogenetic analysis indicated that gynogenetic progeny were diploids with 120 chromosomes. Based on the histological analysis, more than 86% of the gynogenetic individuals were found to be females. Moreover, some males (7%), sterile speciemens (3.5%) and fish with unidentified gonads (3.5%) were observed among the gynogenetic fish. Presence of both females and males in the gynogenetic offspring is indicative that the heterogametic sex in sterlets is female.

Genetic identification of a newly synthetic allopolyploid strain with 206 chromosomes in polyploid gibel carp

A newly synthetic allopolyploid strain (SAS) was selected and established from gynogenetic offspring of gibel carp clone A+ with 156 chromosomes induced by common carp sperm with 50 chromosomes. In this study, the allopolyploid strain was detected to contain 206 chromosomes, and the growth trait was evaluated to have 25.15% growth faster than that of clone A+. Genetic marker analyses of transferrin (Tf) alleles, ITS1 sequences and mtDNA D-loop sequences indicated that the allopolyploid strain was synthetized from maternal gibel carp clone A+ and paternal common carp, and the synthetic chromosome sets were further confirmed by genomic in situ hybridization (GISH) and chromosome localization of 45S rDNA. Significantly, the synthetic allopolyploid strain has tended to be stable by five successive generations of gynogenesis, because it still keeps unisexual reproduction mode of gynogenesis. Therefore, it will become a novel variety for gibel carp aquaculture in future.

Disturbances in the ploidy level in the gynogenetic sterlet Acipenser ruthenus

Artificial mitotic gynogenesis, a chromosome set manipulation, is applied to provide the homozygous progeny with only maternal inheritance. Here, gynogenetic development was induced in the sterlet Acipenser ruthenus L. (Acipenseridae) by activation of the eggs originating from albino females with the UV-irradiated spermatozoa from wild-coloured males, followed by the heat shock applied to suppress the first mitotic division in the haploid zygotes. All experimentally obtained gynogenetic offspring possessed recessive albino coloration. Moreover, the genetic verification, based on three microsatellite DNA markers, confirmed the only maternal inheritance in the albino progeny. Cytogenetic screening enabled identification of the aneuploids, haploids, diploids, triploids, tetraploids and mosaic individuals among the gynogenetic larvae that hatched from the eggs subjected to the heat shock. Furthermore, 40% of the larvae from the haploid variants of the research that were not exposed to the temperature shock showed the diploid chromosome number. A variation of the ploidy level observed in the gynogenetic sterlets may be the consequence of the spontaneous polyploidisation that occurred in the haploid zygotes. Moreover, observation during embryogenesis showed varied stages of eggs development and the asynchronous cell cleavages that may have resulted in the chromosomal disturbances observed in the gynogenetic sterlets here.

Spontaneous polyploidy, gynogenesis and androgenesis in second generation (F2 ) koi Cyprinus carpio × goldfish Carassius auratus hybrids.

The objective of this study was to characterize the genetics of second generation (F2 ) koi Cyprinus carpio × goldfish Carassius auratus hybrids. Spermatozoa produced by a novel, fertile F1 male were found to be diploid by flow-cytometric analysis. Backcross (F1 female × C. carpio male and C. carpio female × F1 male) juveniles were triploid, confirming that female and male F1 hybrids both produced diploid gametes. The vast majority of surviving F2 juveniles was diploid and small proportions were aneuploid (2·1n-2·3n and 3·1n-3·9n), triploid (3n) and tetraploid (4n). Microsatellite genotyping showed that F2 diploids repeated either the complete maternal or the complete paternal genotype. Fish with the maternal genotype were female and fish with the paternal genotype were male. This demonstrates that F2 diploids were the result of spontaneous gynogenesis and spontaneous androgenesis. Analysis of microsatellite inheritance and the sex ratio in F2 crosses showed that spontaneous gynogenesis and androgenesis did not always occur in equal proportions. One cross was found to have an approximate equal number of androgenetic and gynogenetic offspring while in several other crosses spontaneous androgenesis was found to occur more frequently than spontaneous gynogenesis.

Induced gynogenesis of sturgeon with expertise of offspring origin by microsatellite DNA markers

The approach for the application of the gynogenesis induction method of sturgeon based on physical methods to influence the sexual products was considered. As a result of this work, the optimal exposure settings of the bester sperm by ultraviolet rays and gynogenesis induction of the sterlet by the thermal shock were defined. The origin of the obtained gynogenetic offspring was proved by the expertise of microsatellite DNA markers