The Key Roles of Makorin RING Finger Protein 3 (MKRN3) During the Development of Pubertal Initiation and Central Precocious Puberty (CPP).

Puberty is initiated from the continuous and growing pulsatile secretion of gonadotropin-releasing hormone (GnRH) in the hypothalamus and then the activation of the hypothalamic-pituitary-gonadal (HPG) axis. Numerous factors involve pubertal initiation, whose abnormality may come from the dysfunction of these regulators. Makorin RING finger protein 3 (MKRN3) inhibits the secretion of GnRH and plays indispensable roles during the development of pubertal onset, and mutations of MKRN3 showed the commonest genetic cause of central precocious puberty (CPP). Recently, growing studies have revealed the functional mechanisms of MKRN3 in the pubertal initiation and the occurrence of CPP. In this review, we mainly summarized the research advances on the roles of MKRN3 in the development of pubertal onset and their underpinning mechanisms, contributing to a better understanding of the precise mechanisms of pubertal initiation and the pathogenesis of CPP.

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 (Carassius auratus, GF, 2n = 100) and Bleeker's yellow tail (Xenocypris davidi 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. All GFYT hybrids possessed 124 chromosomes (3n = 124) with two sets from GF and one set from YT. The measurable and countable traits of GFYT hybrids were identified, and the genetic characteristics of 5S rDNA between GFYT hybrids and their parents were also revealed. There were, respectively, four and three different 5S rDNA types in GF (assigned as GF-Ⅰ∼Ⅳ) and YT (assigned as YT-Ⅰ∼Ⅲ), and GFYT hybrids specifically inherited YT-Ⅰ and YT-Ⅱ 5S rDNA types from YT and GF-Ⅲ and GF-Ⅳ from GF. In addition, there were only testis-like and fat-like gonads been found in GFYT hybrids. Interestingly, there were pyknotic and heteromorphous chromatin and invaginated cell membrane observed in the spermatids of testis-like gonads, but no mature sperm were found. Furthermore, TUNEL assays indicated that, compared with control, apparent apoptotic signals, which were mainly distributed around spermatid regions, were detected in the testis-like gonads, and the expression of apoptosis pathway-related genes including p53, bcl-2, bax, and caspase9 was significantly upregulated. Moreover, the expression of meiosis-related genes including spo11, dmc1, and rad51 showed an abnormally high expression, but mns1 and meig1, two key genes involved in the maturation of spermatid, were extremely downregulated. In brief, this is the first report of allotriploid via distant hybridization between GF and YT that possessing different chromosome numbers in vertebrates. The obtainment of GFYT hybrids not only harbors potential benefits and application in aquaculture but also further extends the understanding of the influence of hybridization and polyploidization on the genomic constitution of the hybrid offspring. Furthermore, they can be used as a model to test the origin and consequences of polyploidization and served as a proper resource to study the underlying mechanisms of spermatogenesis dysfunctions.

Corrigendum: Genetic Variation in an Experimental Goldfish Derived From Hybridization.

[This corrects the article DOI: 10.3389/fgene.2020.595959.].

Genetic Variation in an Experimental Goldfish Derived From Hybridization.

Owning to the extreme difficulty in identifying the primary generation (G0), the common ancestor of various twin-tail goldfish strains remains unclear. However, several authors have hypothesized that this ancestor may have been the crucian carp (Carassius auratus). Previously, we generated an experimental hybrid goldfish (EG) from the interspecific hybridization of red crucian carp (Carassius auratus ♀, RCC) × common carp (Cyprinus carpio ♂, CC). Unlike either parent, EG possessed twin caudal fins similar to those of natural goldfish (Carassius auratus, NG). The genetic characteristics of EG, as well as the mechanisms underlying its formation, are largely unknown. Here, we identified the genetic variation in the chordin gene that was associated with the formation of the twin-tail phenotype in EG: a stop codon mutation at the 127th amino acid. Furthermore, simple sequence repeat (SSR) genotyping indicated that, among the six alleles, all of the EG alleles were also present in female parent (RCC), but alleles specific to the male parent (CC) were completely lost. At some loci, EG and NG alleles differed, showing that these morphologically similar goldfish were genetically dissimilar. Collectively, our results demonstrated that genetic variations and differentiation contributed to the changes of morphological characteristics in hybrid offspring. This analysis of genetic variation in EG sheds new light on the common ancestor of NG, as well as on the role of hybridization and artificial breeding in NG speciation.

Synthesis of novel genistein amino acid derivatives and investigation on their interactions with bovine serum albumin by spectroscopy and molecular docking.

Genistein amino acid derivatives 4a-4d were synthesized and evaluated for their cytotoxic activities against MCF-7, Hela, MGC-803 and HCT-116 cell lines by MTT assays in vitro. The results revealed that compounds 4a-4d showed better activity than the parent compound genistein. Particularly, compound 4b displayed the most significant anticancer activity against MGC-803 with an IC50 value of 12.08 µM. In addition, the mechanisms of interaction between genistein, compounds 4a-4d and BSA were investigated via multi-spectroscopic techniques such as ultraviolet (UV) spectroscopy, fluorescence, circular dichroism (CD), and molecular docking under physiological conditions. The results suggested that endogenous fluorescence of BSA could be quenched by genistein and compounds 4a-4dvia forming BSA-compound complex, which meant a static quenching mechanism was involved. The negative values of enthalpy (ΔH) and entropy (ΔS) indicated that interactions between BSA and the ligands were spontaneous, and hydrogen bonding and van der Waals interactions were involved in the BSA-compound complexion formation. The UV, synchronous and 3D fluorescence results revealed that the micro-environment of tryptophan and conformation of BSA were changed after binding to ligands. CD analysis demonstrated the variation in the secondary structure and that the α-helix content of BSA decreased. Eventually, molecular docking was executed to forecast the binding forces and binding sites between BSA and compounds 4a-4d.

The formation of diploid and triploid hybrids of female grass carp × male blunt snout bream and their 5S rDNA analysis.

BACKGROUND: Hybridization is a useful strategy to alter the genotypes and phenotypes of the offspring. It could transfer the genome of one species to another through combing the different genome of parents in the hybrid offspring. And the offspring may exhibit advantages in growth rate, disease resistance, survival rate and appearance, which resulting from the combination of the beneficial traits from both parents. RESULTS: Diploid and triploid hybrids of female grass carp (Ctenopharyngodon idellus, GC, Cyprininae, 2n = 48) × male blunt snout bream (Megalobrama amblycephala, BSB, Cultrinae, 2n = 48) were successfully obtained by distant hybridization. Diploid hybrids had 48 chromosomes, with one set from GC and one set from BSB. Triploid hybrids possessed 72 chromosomes, with two sets from GC and one set from BSB.The morphological traits, growth rates, and feeding ecology of the parents and hybrid offspring were compared and analyzed. The two kinds of hybrid offspring exhibited significantly phenotypic divergence from GC and BSB. 2nGB hybrids showed similar growth rate compared to that of GC, and 3nGB hybrids significantly higher results. Furthermore, the feeding ecology of hybrid progeny was omnivorous.The 5S rDNA of GC, BSB and their hybrid offspring were also cloned and sequenced. There was only one type of 5S rDNA (designated type I: 180 bp) in GC and one type of 5S rDNA (designated type II: 188 bp) in BSB. However, in the hybrid progeny, diploid and triploid hybrids both inherited type I and type II from their parents, respectively. In addition, a chimera of type I and type II was observed in the genome of diploid and triploid hybrids, excepting a 10 bp of polyA insertion in type II sequence of the chimera of the diploid hybrids. CONCLUSIONS: This is the first report of diploid and triploid hybrids being produced by crossing GC and BSB, which have the same chromosome number. The obtainment of two new hybrid offspring has significance in fish genetic breeding. The results illustrate the effect of hybridization and polyploidization on the organization and variation of 5S rDNA in hybrid offspring.

Organization and variation analysis of 5S rDNA in different ploidy-level hybrids of red crucian carp × topmouth culter.

Through distant crossing, diploid, triploid and tetraploid hybrids of red crucian carp (Carassius auratus red var., RCC♀, Cyprininae, 2n = 100) × topmouth culter (Erythroculter ilishaeformis Bleeker, TC♂, Cultrinae, 2n = 48) were successfully produced. Diploid hybrids possessed 74 chromosomes with one set from RCC and one set from TC; triploid hybrids harbored 124 chromosomes with two sets from RCC and one set from TC; tetraploid hybrids had 148 chromosomes with two sets from RCC and two sets from TC. The 5S rDNA of the three different ploidy-level hybrids and their parents were sequenced and analyzed. There were three monomeric 5S rDNA classes (designated class I: 203 bp; class II: 340 bp; and class III: 477 bp) in RCC and two monomeric 5S rDNA classes (designated class IV: 188 bp, and class V: 286 bp) in TC. In the hybrid offspring, diploid hybrids inherited three 5S rDNA classes from their female parent (RCC) and only class IV from their male parent (TC). Triploid hybrids inherited class II and class III from their female parent (RCC) and class IV from their male parent (TC). Tetraploid hybrids gained class II and class III from their female parent (RCC), and generated a new 5S rDNA sequence (designated class I-N). The specific paternal 5S rDNA sequence of class V was not found in the hybrid offspring. Sequence analysis of 5S rDNA revealed the influence of hybridization and polyploidization on the organization and variation of 5S rDNA in fish. This is the first report on the coexistence in vertebrates of viable diploid, triploid and tetraploid hybrids produced by crossing parents with different chromosome numbers, and these new hybrids are novel specimens for studying the genomic variation in the first generation of interspecific hybrids, which has significance for evolution and fish genetics.