Formation of Different Polyploids Through Disrupting Meiotic Crossover Frequencies Based on cntd1 Knockout in Zebrafish.

Polyploidy, a significant catalyst for speciation and evolutionary processes in both plant and animal kingdoms, has been recognized for a long time. However, the exact molecular mechanism that leads to polyploid formation, especially in vertebrates, is not fully understood. Our study aimed to elucidate this phenomenon using the zebrafish model.

Formation of the synaptonemal complex in a gynogenetic allodiploid hybrid fish.

The correct pairing and separation of homologous chromosomes during meiosis is crucial to ensure both genetic stability and genetic diversity within species. In allodiploid organisms, synapsis often fails, leading to sterility. However, a gynogenetic allodiploid hybrid clone line (GDH), derived by crossing red crucian carp ( ♀) and common carp ( ♂), stably produces diploid eggs.

Symmetric subgenomes and balanced homoeolog expression stabilize the establishment of allopolyploidy in cyprinid fish.

Background: Interspecific postzygotic reproduction isolation results from large genetic divergence between the subgenomes of established hybrids. Polyploidization immediately after hybridization may reset patterns of homologous chromosome pairing and ameliorate deleterious genomic incompatibility between the subgenomes of distinct parental species in plants and animals. However, the observation that polyploidy is less common in vertebrates raises the question of which factors restrict its emergence.

A Novel Allotriploid Hybrid Derived From Female Goldfish × Male Bleeker's Yellow Tail.

Hybridization is a traditional and effective strategy to alter the genotypes and phenotypes of the offspring, and distant hybridization is a useful strategy to generate polyploids in fish. In this study, goldfish (, GF, 2n = 100) and Bleeker's yellow tail ( Bleeker, YT, 2n = 48), which belong to different subfamilies, were crossed with each other. The cross of female GF × male YT successfully obtained hybrid offspring (GFYT hybrids), while the cross of female YT × male GF was lethal, and all the fertilized eggs stopped developing before the neurula stage of embryogenesis.

Localization of RNA Pol II CTD (S5) and Transcriptome Analysis of Testis in Diploid and Tetraploid Hybrids of Red Crucian Carp (♀) × Common Carp (♂).

Polyploidy occurs naturally in fish; however, the appearance of these species is an occasional and gradual process, which makes it difficult to trace the changes in phenotypes, genotypes, and regulation of gene expression. The allotetraploid hybrids (4nAT) of red crucian carp (RCC; ♀) × common carp (CC; ♂) generated from interspecies crossing are a good model to investigate the initial changes after allopolyploidization. In the present study, we focused on the changes in the active sites of the testicular transcriptome of the allotetraploid by localization of RNA Pol II CTD YSPTSPS (phospho S5) using immunofluorescence and RNA-seq data bioinformatic analysis.

Elevated expression of inhibin α gene in sterile allotriploid crucian carp.

Inhibin and Activin, belong to the transforming growth factor β superfamily (TGF-β), which associate with the regulation of the reproductive process by the modulation of the hypothalamic-pituitary-gonad (HPG) axis. In this study, we reported the molecular cloning and tissue expression of inhibin α in allotriploid crucian carp and its parent- diploid red crucian carp. The full-length cDNA of inhibin α were respectively 1632 bp and 1642 bp in allotriploids and diploids, which both consisted of a 1044 bp open reading frame (ORF) encoding 347 amino acids.

Abnormal meiosis in fertile and sterile triploid cyprinid fish.

Meiosis is the key process for producing mature gametes. A natural fertile triploid Carassius auratus population (3nDTCC) and an artificially derived sterile triploid crucian carp (3nCC) have been previously observed, providing suitable model organisms for investigating meiosis characteristics in triploid fish. In the present study, the microstructures and ultrastructures of spermatogenesis were studied in these fishes.

Comparative analyses of hypothalamus transcriptomes reveal fertility-, growth-, and immune-related genes and signal pathways in different ploidy cyprinid fish.

Triploid crucian carp (TCC) is obtained by hybridization of female diploid red crucian carp (Carassius auratus red var., RCC) and male allotetraploid hybrids. In this study, high-throughput sequencing was used to conduct the transcriptome analysis of the female hypothalamus of diploid RCC, diploid common carp (Cyprinus carpio L.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var.

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs.

The Hybrid Genome of a New Goldfish-Like Fish Lineage Provides Insights Into the Origin of the Goldfish.

Distant hybridization leads to obvious changes in genotypes and phenotypes, giving rise to species with novel capabilities. However, the fusion of distinct genomes also polymerizes the DNA or gene variations that occur during the course of evolution. Knowledge of the early stages of post-hybridization evolution is particularly important.

Hox genes reveal variations in the genomic DNA of allotetraploid hybrids derived from Carassius auratus red var. (female) × Cyprinus carpio L. (male).

Background: Hox transcription factors are master regulators of animal development. Although highly conserved, they can contribute to the formation of novel biological characteristics when modified, such as during the generation of hybrid species, thus potentially serving as species-specific molecular markers. Here, we systematically studied the evolution of genomic sequences of Hox loci in an artificial allotetraploid lineage (4nAT, 4n = 200) derived from a red crucian carp (♀, RCC, 2n = 100) × common carp (♂, CC, 2n = 100) cross and its parents (RCC and CC).

Evolutionary dynamics of 18S and 5S rDNA in autotriploid Carassius auratus.

The Carassius auratus (crucian carp) complex of the Dongting water system exhibits coexistence of diploid and triploid forms. As reported, triploid C. auratus is autotriploid origin.

The subgenomes show asymmetric expression of alleles in hybrid lineages of × .

Hybridization drives rapid speciation by shaping novel genotypic and phenotypic profiles. Genomic incompatibility and transcriptome shock have been observed in hybrids, although this is rarer in animals than in plants. Using the newly sequenced genomes of the blunt snout bream ( [BSB]) and the topmouth culter ( [TC]), we focused on the sequence variation and gene expression changes in the reciprocal intergeneric hybrid lineages (F-F) of BSB × TC.

Diploid hybrid fish derived from the cross between female Bleeker's yellow tail and male topmouth culter, two cyprinid fishes belonging to different subfamilies.

Background: Bleeker's yellow tail (Xenocypris davidi Bleeker, YT) and topmouth culter (Culter alburnus Basilewsky, TC) are both famous and important economic freshwater fish in China. YT, a kind of omnivorous fish, has strong resistance. TC, a kind of carnivorous fish, has high-quality meat but poor resistance.

Differential expression of activin β and β genes in female allotriploid and diploid red crucian carp Carassius auratus red var.

activin β and β from diploid and allotriploid crucian carp were cloned.The differential expression of activin β and β genes in female allotriploid and diploid red crucian carp Carassius auratus red var. were studied and found to be expressed in all the tested tissues; particularly, the expression of activin β and β was elevated in the ovaries of allotriploids and differential expression in pituitaries during the non-breeding season and the breeding season period.

Correction to: Analysis of Chromosomal Numbers, Mitochondrial Genome, and Full-Length Transcriptome of Onychostoma brevibarba.

The original version of this article unfortunately contained an error in the abstract section. In line 5, the phrase "..

Analysis of Chromosomal Numbers, Mitochondrial Genome, and Full-Length Transcriptome of Onychostoma brevibarba.

Onychostoma brevibarba is a new discovered species which is distributed in Xiang Jiang River of the middle Chang Jiang basin in Hunan Province, South China. In this study, the ploidy levels of O. brevibarba were confirmed by counting chromosomal numbers and analyzing karyotype.

The Sterility of Allotriploid Fish and Fertility of Female Autotriploid Fish.

Based on the formation of an autotetraploid fish line (4nAUT, 4n = 200; F-F) derived from the distant hybridization of female red var. (RCC, 2n = 100) × male (BSB, 2n = 48), we produced autotriploid hybrids (3nAUT) by crossing females of RCC with males of 4nAUT and allotriploid hybrids (3nALT) by crossing females of (CC, 2n = 100) with males of 4nAUT. The aim of this study was to comparatively investigate the reproductive characteristics of 3nALT and 3nAUT.

Genetic Effects on the Gut Microbiota Assemblages of Hybrid Fish From Parents With Different Feeding Habits.

Gut microbiota play critical roles in host nutrition and metabolism. However, little is known about the genetic effects on the gut microbiota assemblages because a suitable model for investigation is lacking. In the present study, we established the reciprocal hybrid fish lineages derived from the parents with different feeding habits, namely, herbivorous blunt snout bream (, BSB, 2n = 48) and carnivorous topmouth culter (, TC, 2n = 48).

Establishment and application of distant hybridization technology in fish.

Hybridization is widely used. However, for a long time, systematic theories and technologies related to hybridization in fish have been lacking. In this study, through long-term systematic research, we investigated and obtained the main rules regarding inheritance and reproduction related to fish distant hybridization.

Comparative analysis of testis transcriptomes associated with male infertility in triploid cyprinid fish.

Spermatogenesis involves a series of cellular transformations and thousands of regulated genes. Previously, we showed that the triploid fish (3nBY) cannot produce mature spermatozoa. In the present study, evaluation of the testis microstructure revealed that germ cells of 3nBY could develop into round spermatids, but then degenerated, resulting in male infertility.

Asymmetric expression patterns reveal a strong maternal effect and dosage compensation in polyploid hybrid fish.

Background: Hybridization and polyploidization are regarded as the major driving forces in plant speciation, diversification, and ecological adaptation. Our knowledge regarding the mechanisms of duplicated-gene regulation following genomic merging or doubling is primarily derived from plants and is sparse for vertebrates.

Results: We successfully obtained an F1 generation (including allodiploid hybrids and triploid hybrids) from female Megalobrama amblycephala Yih (BSB, 2n = 48) × male Xenocypri davidi Bleeker (YB, 2n = 48).

The chimeric genes in the hybrid lineage of Carassius auratus cuvieri (♀)×Carassius auratus red var. (♂).

Hybridization can combine the genomes of different strains or species, which leads to changes of genotype and phenotype in the hybrids. In this study, we aimed to investigate the genetic variations of hybrids (WR-F and WR-F) derived from the intraspecific hybridization of white crucian carp (Carassius auratus cuvieri, WCC, ♀) and red crucian carp (Carassius auratus red var., RCC, ♂).

A new type of homodiploid fish derived from the interspecific hybridization of female common carp × male blunt snout bream.

It is commonly believed that hybridization might lead to the formation of new polyploidy species, but it is unclear whether hybridization can produce a new homodiploid species. Here, we report the spontaneous occurrence of a new crucian carp-like homodiploid fish (2n = 100) that originated from the interspecific hybridization of female common carp (Cyprinus carpio, Cyprininae, 2n = 100) × male blunt snout bream (Megalobrama amblycephala, Cultrinae, 2n = 48). The phenotype and reproductive traits of this new crucian carp-like homodiploid fish were found to be very similar to those of the existing diploid species (diploid crucian carp; Carassius auratus).