Search

The kisspeptin system, which involves hypothalamic neuropeptides, plays pivotal roles in the regulation of teleost reproduction. A previous study suggested that the kiss2/kissr2 system in largemouth bass (Micropterus salmoides) was involved in regulating gonadal development through the hypothalamus-pituitary-gonad (HPG) axis. However, whether the kiss2/kiss2r system directly regulates the activity of pituitary gland were not studied. This study aimed to elucidate the detailed mechanism of kisspeptin-induced effects on gonadotropin hormoneproducing cells in vivo and in vitro. In situ hybridization analysis revealed very widespread expression of kiss2r mRNA in the optic tectum, hypothalamus and pituitary. In the pituitary, kiss2r-expressing cells were mainly located in the proximal pars distalis and pars intermedia, among which the fshβ- and lhβ-positive cells exhibited expression of kiss2r messengers. Furthermore, primary culture of pituitary cells and peptide administration experiments revealed that the Kiss2-10 peptide stimulates the expression of fshβ and lhβ and the secretion of FSH and LH in 24 h. In addition, histology analysis revealed that three injections of the Kiss2-10 peptide promoted ovary development and increased oocyte size but had little effect on testis development. These results suggested that the intrapituitary kisspeptinergic system, as a hypophysiotropic neuropeptide factor, directly modulates of gonadotroph function. This study will help uncover the reproductive endocrinology network and improve artificial breeding technology for largemouth bass. [ABSTRACT FROM AUTHOR]

Sexual selection is critical to animal reproduction. Mate choice not only determines an individual’s capacity for reproduction but is also the primary mode of selection in sexual selection. Mate choice behavior relies on social information, and animals can extract useful information (e.g., genetic quality, hormone levels, physiological status, habitat) about potential mates based on morphological and behavioral traits they observe or perceive and can modify their mate choice strategy by detecting and integrating this information. The information conveyed by potential mates is multimodal. This paper synthesizes the effects of several factors, including individual biological characteristics, sensory systems, hormones and genotype on mate choice, demonstrating that mate choice preferences in the traditional sense are generally more favorable for individuals with superior genes and phenotypes. And the paper also explores the limitations of these studies on mate choice and proposes the future major trend of the correlational research in this field. This work will provide helpful information for guiding the subsequent studies of mate choice in animals. [ABSTRACT FROM AUTHOR]

The common carp (Cyprinus carpio L., COC, 2n = 100) is one of the most widely consumed and distributed freshwater fish in the world. It ranks fourth in total freshwater aquaculture volume in various regions of China, behind Ctenopharyngodon idella, Hypophthalmichthys molitrix, and Aristichthys nobilis. However, in recent years, environmental degradation, inbreeding, disordered breeding, and other adverse effects have caused problems such as low seed quality and poor disease and stress resistance of the carp. In our laboratory, we developed two types of improved diploid carp the hybrid F1 of common carp (♀) × blunt snout bream (Megalobrama amblycephala, BSB, 2n = 48) (♂). To investigate the differences between IDC and IDMC compared to COC, in this study we compared the relevant characteristics of these two types of improved carp with those of COC in terms of muscle nutrient composition, intermuscular bone type, and number. The results showed that among the muscle nutrients, IDC had a higher protein content (18.50%) and lower carbohydrate content (0.70%). In addition, the unsaturated fatty acid content of IDC (3.45%) and IDMC (1.25%) were significantly higher than that of COC (P < 0.05) (0.50%). For monounsaturated fatty acids such as oleic acid (OA, C18:1 n-9) and linoleic acid (PA, C16:1), the content of IDC and IDMC were also abundant. In terms of intermuscular bone morphology, the morphology and type of intermuscular bone in IDC and IDMC medullary arch ossicles were consistent with those of COC. However, the number of intermuscular bones was different, and the average number of intermuscular bones of IDMC decreased by 14.77% (P < 0.05) compared with COC. The advantages of IDC and IDMC are different, with IDC having a higher value of muscle nutrients and IDMC having a lower intermuscular bone content. The distant hybridization of common carp (♀) × blunt snout bream (♂) developed two improved diploid carp varieties with excellent traits, which added carp germplasm resources with high muscle nutrition and lower intermuscular bone, and provided theoretical support for their production application. [ABSTRACT FROM AUTHOR]

Background: Polyploidy and hybridization are both recognized as major forces in evolution. Most of our current knowledge about differences in gene regulation in polyploid hybrids comes from plant studies. The gene expression of diverged genomes and regulatory interactions are still unclear in lower vertebrates. Results: We generated 229 million cleaned reads (42.23 Gbp) from triploid of maternal grass carp (Ctenopharyngodon idellus, Cyprininae, 2n = 48) x paternal blunt snout bream (Megalobrama amblycephala, Cultrinae, 2n = 48) and their diploid parents using next-generation sequencing. In total, 157,878 contigs were assembled and 15,444 genes were annotated. We examined gene expression level changes among the parents and their triploid offspring. The mechanisms of dosage compensation that reduced triploid expression levels to the diploid state were determined in triploid fish. In this situation, novel gene expression and gene silencing were observed. Then, we established a model to determine the extent and direction of expression level dominance (ELD) and homoeolog expression bias (HEB) based on the relative expression level among the parents and their triploid offspring. Conclusions: Our results showed that the genome-wide ELD was biased toward maternal genome in triploid. Extensive alterations in homoeolog expression suggested a combination of regulatory and epigenetic interactions through the transcriptome network. Additionally, the expression patterns of growth genes provided insights into the relationship between the characteristics of growth and underlying mechanisms in triploids. Regulation patterns of triploid state suggest that various expression levels from the initial genomic merger have important roles in adaptation. [ABSTRACT FROM AUTHOR]

Background: Nucleolar dominance is an epigenetic phenomenon that occurs in interspecific hybrids and involves the expression of 45S rRNA genes inherited from one progenitor due to the silencing of the other progenitor's rRNA genes. In this paper, changes in the genetics and expression of 45S rRNA genes in F1 and F2 hybrid progeny of blunt snout bream (BSB, Megalobrama amblycephala) × topmouth culter (TC, Culter alburnus) are investigated. Results: The 45S rDNA loci were analyzed by cloning, RT-PCR and sequencing methods. The results show that nucleolar dominance patterns differ in the F1 and F2 hybrids. In the F1 hybrids of BSB × TC, all the tested individuals inherited and expressed the 45S rRNA genes of both BSB and TC, indicating that nucleolar dominance is not established in the F1 hybrids. However, in the F2 hybrids of BSB × TC, five patterns are observed. Pattern 1 inherits and expresses only the 45S rRNA gene of BSB. Pattern 2 inherits the 45S rRNA gene from both BSB and TC, but only expresses the 45S rRNA of BSB. Pattern 3 inherits and expresses the 45S rRNA gene from both BSB and TC. Pattern 4 inherits the 45S rRNA gene from both BSB and TC, but only expresses the 45S rRNA gene of TC. Pattern 5 inherits and expresses only the 45S rRNA gene of TC. Conclusions: Nucleolar dominance shows distinctive patterns in intergeneric hybrids of BSB × TC. It is not established in F1 hybrids and is random in F2 hybrids. This study provides new insights into the phenomenon of nucleolar dominance in genetic hybrids in vertebrates. [ABSTRACT FROM AUTHOR]