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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.

Multiple phase transformations were carried out during dehydrogenation process of TiH2-based powder metallurgy. The influence of phase transformation on the microstructure is highly worthy of attention. In situ synchrotron radiation was employed to investigate the phase transformation sequence of TiH2 powder compact during the vacuum sintering process. It was found that a transformation route TiH1.971 → TiH2 + TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) + β(H) → α(H) → α took place, resulting in an equiaxed microstructure. Increasing heating rate and avoiding the intense dehydrogenation to retain hydrogen-rich β (β(H)) and TiHx aciculae at the interfaces is found to be a feasible method to fabricate hierarchical α-Ti structures. A fully dense fine martensitic microstructure was produced after fast heating the TiH2 powder compact to 1100 °C and an immediate hot extrusion. Subsequently, by vacuum annealing treatment at 700 °C, composite α/βt lamellar structures were generated and a simultaneously enhanced tensile strength of 746 MPa and excellent elongation to fracture of 33.8% were achieved. It is suggested that adjusting the dehydrogenation reactions of TiH2-based powder metallurgy is conductive to generating hierarchical lamellar structures with a highly promising combination of strength and ductility for pure Ti.

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

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 hormone-producing 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.

Artificial gynogenesis is an important method for accelerating the selective breeding of varieties and populations. In this study, ultraviolet-irradiated sperm of Common carp (Cyprinus carpio) was used to activate the mature eggs of mrigal carp (Cirrhinus mrigala, MC), after cold shock at 4–8 °C for 16 min to double the chromosomes, a population of gynogenetic mrigal carp (GMC) was obtained. The fertilization rate, hatching rate and survival rate of GMC exceeded 62.2%, 6.3% and 2.9%, respectively. Comparative analyses of morphological traits, DNA content, chromosome numbers and 5S rDNA sequences showed no significant differences between MC and GMC. However, microsatellite (MFW1, CCA15) analysis revealed that paternal DNA fragments were inserted and a parent DNA fragment was deleted in the GMC. The GMC population survived the natural winter for more than 50 days with a temperature below 10 °C, while all the normal MC individuals perished. In addition, lower critical thermal minimum (CTMin) and lethal temperature (TLD50) values were detected in GMC than that in MC. Our results indicated that the artificial gynogenesis method improved the cold tolerance of mrigal carp. The results of this study are of great significance for fish breeding and application.

Micropterus salmoides is an economically important cultured carnivorous fish in China. In recent years, owing to the development and wide application of artificial formula feed, M. salmoides production has rapidly increased and reached 470 000 tons in 2019. However, a low survival rate of M. salmoides larvae is observed during the first feeding and artificial formula feed adaptation.In this study, to better understand the artificial formula feed adaptation of M. salmoides larvae, the developmental characteristics of the digestive tract and digestive gland of the fish larvae from 2~30 dph were observed and described using histological sections and scanning electron microscopy (SEM). Moreover, the digestive tract (stomach and intestine) characteristics of certain dead larval fish during the first feeding and the transformation of artificial formula feed were investigated.For histological analysis, the larval fish (including stomach, intestine, pyloric cecum, liver, and pancreas tissues) were dehydrated with an alcohol gradient (70%, 80%, 90%, and 100%), embedded in paraffin, cut into 5 μm sections, and stained with standard hematoxylin and eosin.For SEM analysis, the stomach, pyloric cecum, and intestine of 30 dph larval fish were fixed in 2.5% glutaraldehyde solution for 12 h. Then, the tissues were fixed in 1% osmium solution for 2 h, dehydrated with gradient alcohol (70%~100%), soaked in tert-butyl alcohol for 2 h, dried with a lyophilizer, and plated with gold by ion sputtering. Finally, the images were captured using a HITACHIX-650 scanning electron microscope.At a water temperature of (23±1)℃, the larval yolk sac and oil drop gradually decreased at 0~4 dph, the digestive tract was initially differentiated, and heartbeat, blood circulation, mouth crack, esophagus, and anus were observed at 4 dph. Larval fish were in the endogenous nutrition period at this stage. In 4~ 6 dph larval fish, the esophagus, stomach, intestine, liver, and pancreas regions gradually formed, the digestive tube opened to the outside initially, and yolk sac and oil drop significantly decreased and then completely disappeared, indicating that the larval fish entered the endo-exotrophic period. At this stage, sufficient Artemia salina should be provided to induce the larval fish to open their mouth and perform first feeding. In 10~16 dph larval fish, the stomach, pylorus caecum, and intestine were closely arranged. From the surface of the intestinal cavity, the mucosa, submucosa, muscular, and serosa layers were successively presented. The size of the mucosa columnar epithelial cells and the number of goblet cells clearly increased. The masses of hepatocytes and pancreatic cells significantly increased, and a vacuole structure appeared in the hepatocytes. The pancreatic cells were arranged closely, and the blood cells and pancreatic ducts were distributed. At this stage, larval fish entered the exogenous nutrition period. From this stage onward, larval fish are better able to transform feeding artificial formula feed step by step. In 20~24 dph larval fish, the stomach gland was well developed, and the stomach wall thickness and number of stomach glands further increased. Furthermore, the mucosal folds and connective tissue of the submucosa were further differentiated, and the longitudinal mucosal folds increased and curled. In addition, secondary mucosal folds in the intestine gradually appeared and the number of mucosal folds in the pyloric cecum increased. Fatty accumulation and secretory granules were observed in the liver and pancreas, respectively, indicating that the larval hepatopancreas was similar to that of adult fish. The digestive system of larval fish was completely developed at this stage, and the larval fish had the ability to transform and adapt to artificial formula feed.No significant differences were observed in body length and body weight of M. salmoides larvae (P > 0.05) during the adaptation to artificial formula feed at 12, 16, and 20 dph. However, the survival rate of 12 dph larval fish (45.59%) was lower than that of 16 (60.60%) and 20 dph larval fish (69.83%). In addition, the body length, body weight, and survival rate of M. salmoides larvae were positively correlated with the time point of feeding artificial formula feed.SEM results showed abundant polygonal reticular mucosal folds in the gastric epidermis of 30-day-old larval fish, and there were dense secretion pores between the gastric pits. Mucosa folds with fixed shapes were observed on the inner surface of the intestine, and mucous cells, secretory pores, and secretory granules were clearly observed between the mucosal folds. Interestingly, the inner surface structure of the pyloric cecum was similar to that of the intestine. A difference was the mucosa folds without a fixed shape on the inner surface of the pyloric caecum. These mucosal folds and secretory pores are important for food digestion, absorption, and excretion, indicating that the larval fish are old enough to adapt to the artificial formula feed at this point.During the first feeding and artificial formula feed adaptation, the stomach and intestine of the larval fish were incompletely developed and accompanied by tissue damage in the dead individuals. For example, the stomach and intestinal cavity were significantly shriveled, the inner epidermis did not have the molding mucous membrane fold and goblet cells, and the mucous membrane layer was cracked or absent. These results indicate that larval fish overfeed and fail to effectively digest, absorb, and expel nutrients, which ultimately results in death associated with nutritional deficiencies, intestinal blockages, and inflammation.During the process of adaptation to artificial formula feed for M. salmoides, the development of larval digestive system was investigated. The digestive system of larval fish at 4~6 dph gradually differentiated and was still in the mixed nutrition period, and sufficient A. salina should be provided to induce the larval fish to open their mouths and perform the first feeding. At 6~16 dph, the digestive system gradually developed and larval fish entered the exogenous nutrition period, and sufficient food could be provided. At 16~20 dph, the digestive system of the larval fish completely developed, and this stage is the optimal time to switch to artificial formula feed. Our study provides basic data for feeding condition optimization of M. salmoides larvae.

Calcite particles (Source; CaCO3, ∼0.4 μm in size) were 3D-printed into cube honeycombs (honeycombs) with ∼0.7 mm thick struts and ∼0.6 mm cellular window opening. The sintered honeycombs, regardless of the presence of a sintering aid in the printing slurry, gave ∼3 MPa or more in the compressive stress, which exceeded that of trabecular bone. The conversion of calcite to hydroxyapatite (HAp) was assessed in 0.1 M K2HPO4 (pH: 7.0 or 7.4) at 20 °C–80 °C due to the X-ray diffraction intensity of the calcite and HAp peaks, surface microstructure, and P(V) accumulation on the honeycomb strut surface. Although a premature HAp layer yielded on all samples within 1 h soaking, further conversion depended on the samples. The conversion continued on Source until the volume fraction of the HAp shell layer reached ∼35% (37 °C). It was hardly detected on the grains of sintered honeycombs (from the slurry with the sintering aid) within the whole soaking period (≤24 h). In contrast, the conversion on the sintered honeycombs (from the slurry without the aid) became vigorous when soaked for 5 h, and, it reached at 24 h the highest level that the as-printed honeycombs achieved. The critical factors controlling the conversion were calcite dissolution, the equilibria among the carbonate and phosphate ions, and the rates of migration of Ca(II) and P(V) through the inter-granular channels of pores within the struts. A particle stacking model was proposed for the most plausible interpretation of the present results.

The nano-Zirconia powders doped with different yttrium content (YSZ) were prepared by hydrothermal method, and then calcined in the atmosphere. The grain growth kinetics and mechanism of YSZ powder were analyzed. The addition of Y2O3 can refine the zirconia grains, and the mechanism of its action is discussed, and the grain sizes of the hydrothermal nano-powders (0, 3 and 11 YSZ) prepared with different Y2O3 are 15.4, 13.7 and 8.0 nm, respectively. The phase transformation mechanism of 3 YSZ powder and the influence mechanism of Y2O3 doping in different stages on powder growth are discussed. The growth mechanism of powder in different stages is analyzed and expounded. The first stage grain growth mechanism of 3 YSZ and 11 YSZ powders is dominated by surface diffusion and grain boundary rotational polymerization growth mechanisms, while the second stage grain growth is dominated by lattice diffusion and grain boundary migration polymerization growth mechanisms.

The surprising variation in the number of Hox clusters and genome structure in ray-finned fish lineages reflects the history of duplications and subsequent lineage-specific gene loss. However, there are few studies on whether Hox clusters in the early generations of hybrid lineages show more significant variation due to the continuous genomic oscillation caused by distant hybridization. We sequenced and analyzed Hox gene clusters from a crucian carp-like homodiploid fish (NCRC) lineage (a new hybrid lineage derived from common carp (Cyprinus carpio) (♀) ​× ​blunt snout bream (Megalobrama amblycephala) (♂)). In the NCRC lineage, we reconstructed seven Hox clusters consisting of 48 Hox genes, ten of which were pseudogenes. The number of putative Hox clusters generated in NCRC-F1 was increased greatly by distant hybridization to an average number almost twice that in the maternal parent. This increasing trend continued in the subsequent self-mating generations of NCRC-F1. In contrast, the number of Hox cluster fragments inherited from the original parents gradually decreased as the number of NCRC lineage generations increased. This pattern was also found in the inheritance of recombinant Hox clusters. In terms of base composition, some genetic rules for the inheritance of these Hox clusters between different generations of the NCRC lineage were identified. Furthermore, the newly derived mutated Hox clusters in the NCRC lineage showed phylogenetic relationships that were closer to either crucian carp or silver crucian carp, revealing a clear evolutionary path. This study deepens our understanding of the evolution of Hox genes in the ray-finned fish clade.

The tensile properties and microstructure of hot extruded GW84 alloy stretching at 200 °C, 250 °C and 300 °C were investigated. The results showed that the alloys had excellent high temperature mechanical properties, when stretching at 250 °C, the ultimate tensile strength of alloy reached peak value, 393 MPa, and the tensile strength stretching at 300 °C reached 354 MPa. During high temperature tensile process, the microstructure markedly changed, which is not recognised in previous researches. Stretching at 200 °C, the precipitate phase was still metastable β′ phase. However, when stretching at 250 °C, the nano β′ precipitate transformed into nano β phase (β′ → β), and the precipitation mechanism is mainly inoculation nucleation of β phase. When stretching at 300 °C, the number of β precipitates increased significantly at triangular grain boundaries, which grew up to sub-micron particles, and precipitation mechanism is mainly growth and coarsening.

Abstract Background Hybridization, which can quickly merge two or more divergent genomes and form new allopolyploids, is an important technique in fish genetic breeding. However, the merged subgenomes must adjust and coexist with one another in a single nucleus, which may cause subgenome interaction and dominance at the gene expression level and has been observed in some allopolyploid plants. In our previous studies, newly formed allodiploid hybrid fish derived from herbivorous Megalobrama amblycephala (♀) × carnivorous Culter alburnus (♂) had herbivorous characteristic. It is thus interesting to further characterize whether the subgenome interaction and dominance derive dietary adaptation of this hybrid fish. Results Differential expression, homoeolog expression silencing and bias were investigated in the hybrid fish after 70 days of adaptation to carnivorous and herbivorous diets. A total of 2.65 × 108 clean reads (74.06 Gb) from the liver and intestinal transcriptomes were mapped to the two parent genomes based on specific SNPs. A total of 2538 and 4385 differentially expressed homoeologous genes (DEHs) were identified in the liver and intestinal tissues between the two groups of fish, respectively, and these DEHs were highly enriched in fat digestion and carbon metabolism, amino acid metabolism and steroid biosynthesis. Furthermore, subgenome dominance were observed in tissues, with paternal subgenome was more dominant than maternal subgenome. Moreover, subgenome expression dominance controlled functional pathways in metabolism, disease, cellular processes, environment and genetic information processing during the two dietary adaptation processes. In addition, few but sturdy villi in the intestine, significant fat accumulation and a higher concentration of malondialdehyde in the liver were observed in fish fed carnivorous diet compared with fish fed herbivorous diet. Conclusions Our results indicated that diet drives phenotypic and genetic variation, and the asymmetric expression of homoeologous genes (including differential expression, expression silencing and bias) may play key roles in dietary adaptation of hybrid fish. Subgenome expression dominance may contribute to uncovering the mechanistic basis of heterosis and also provide perspectives for fish genetic breeding and application.

Siniperca chuatsi feeds on live fry throughout their life. The sustainable development of its farming industry has urgently necessitated the development of artificial diets to substitute live baits. It has been demonstrated that gut microbiota assists in feed adaptation and improves the feed conversion rate in fish. Therefore, this study aimed to understand the potential role of intestinal microorganisms in the domestication of S. chuatsi with a compound diet. Accordingly, we performed 16S rRNA sequencing of the gut microbial communities in S. chuatsi groups that were fed a compound diet (including large and small individuals) and live baits. A total of 2,471 OTUs were identified, and the large individual group possessed the highest number of unique OTUs. The α-diversity index of the gut microbiota in groups that were fed a compound diet was significantly higher (p < 0.05) than that in the live bait group. There were no significant differences in the α-diversity between the large and small individual groups. However, relatively higher numbers of Lactococcus, Klebsiella, and Woeseia were observed in the intestines of the large individual group. Prediction of the metabolic function of the microbiota among these three fish groups by Tax4Fun revealed that most metabolic pathways, such as glycan metabolism and amino acid metabolism, were typically more enriched for the larger individuals. The results indicated that certain taxa mentioned above exist in large individuals and may be closely related to the digestion and absorption of compound diets. The present study provides a basis for understanding the utilization mechanism of artificial feed by S. chuatsi.

Abstract Background Maternal effects contribute to adaptive significance for shaping various phenotypes of many traits. Potential implications of maternal effects are the cause of expression diversity, but these effects on mRNA expression and alternative splicing (AS) have not been fully elucidated in hybrid animals. Results Two reciprocal cross hybrids following hybridization of Megalobrama amblycephala (blunt snout bream, BSB) and Culter alburnus (topmouth culter, TC) were used as a model to investigate maternal effects. By comparing the expression of BSB- and TC- homoeologous genes between the two reciprocal cross hybrids, we identified 49–348 differentially expressed BSB-homoeologous genes and 54–354 differentially expressed TC-homoeologous genes. 2402, 2959, and 3418 AS events between the two reciprocal cross hybrids were detected in Illumina data of muscle, liver, and gonad, respectively. Moreover, 21,577 (TC-homoeologs) and 30,007 (BSB-homoeologs) AS events were found in the 20,131 homoeologous gene pairs of TBF3 based on PacBio data, while 30,561 (TC-homoeologs) and 30,305 (BSB-homoeologs) AS events were found in BTF3. These results further improve AS prediction at the homoeolog level. The various AS patterns in bmpr2a belonging to the bone morphogenetic protein family were selected as AS models to investigate the expression diversity and its potential effects to body shape traits. Conclusions The distribution of differentially expressed genes and AS in BSB- and TC-subgenomes exhibited various changes between the two reciprocal cross hybrids, suggesting that maternal effects were the cause of expression diversity. These findings provide a novel insight into mRNA expression changes and AS under maternal effects in lower vertebrates.

Abstract Background Distant hybridization can generate changes in phenotypes and genotypes that lead to the formation of new hybrid lineages with genetic variation. In this study, the establishment of two bisexual fertile carp lineages, including the improved diploid common carp (IDC) lineage and the improved diploid scattered mirror carp (IDMC) lineage, from the interspecific hybridization of common carp (Cyprinus carpio, 2n = 100) (♀) × blunt snout bream (Megalobrama amblycephala, 2n = 48) (♂), provided a good platform to investigate the genetic relationship between the parents and their hybrid progenies. Result In this study, we investigated the genetic variation of 12 Hox genes in the two types of improved carp lineages derived from common carp (♀) × blunt snout bream (♂). Hox gene clusters were abundant in the first generation of IDC, but most were not stably inherited in the second generation. In contrast, we did not find obvious mutations in Hox genes in the first generation of IDMC, and almost all the Hox gene clusters were stably inherited from the first generation to the second generation of IDMC. Interestingly, we found obvious recombinant clusters of Hox genes in both improved carp lineages, and partially recombinant clusters of Hox genes were stably inherited from the first generation to the second generation in both types of improved carp lineages. On the other hand, some Hox genes were gradually becoming pseudogenes, and some genes were completely pseudogenised in IDC or IDMC. Conclusions Our results provided important evidence that distant hybridization produces rapid genomic DNA changes that may or may not be stably inherited, providing novel insights into the function of hybridization in the establishment of improved lineages used as new fish resources for aquaculture.

Doublesex and mab-3-related transcription factor (dmrt) genes are widely distributed across various biological groups and play critical roles in sex determination and neural development. Here, we applied bioinformatics methods to exam cross-species changes in the dmrt family members and evolutionary relationships of the dmrt genes based on genomes of 17 fish species. All the examined fish species have dmrt1–5 while only five species contained dmrt6. Most fish harbored two dmrt2 paralogs (dmrt2a and dmrt2b), with dmrt2b being unique to fish. In the phylogenetic tree, 147 DMRT are categorized into eight groups (DMRT1–DMRT8) and then clustered in three main groups. Selective evolutionary pressure analysis indicated purifying selections on dmrt1–3 genes and the dmrt1–3–2(2a) gene cluster. Similar genomic conservation patterns of the dmrt1–dmrt3–dmrt2(2a) gene cluster with 20-kb upstream/downstream regions in fish with various sex-determination systems were observed except for three regions with remarkable diversity. Synteny analysis revealed that dmrt1, dmrt2a, dmrt2b, and dmrt3–5 were relatively conserved in fish during the evolutionary process. While dmrt6 was lost in most species during evolution. The high conservation of the dmrt1–dmrt3–dmrt2(2a) gene cluster in various fish genomes suggests their crucial biological functions while various dmrt family members and sequences across fish species suggest different biological roles during evolution. This study provides a molecular basis for fish dmrt functional analysis and may serve as a reference for in-depth phylogenomics.

Abstract 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 duplicated-gene expression patterns of the two types of hybrids were explored using RNA-Seq data. In total, 5.44 × 108 (69.32 GB) clean reads and 499,631 assembled unigenes were obtained from the testis transcriptomes. The sequence similarity analysis of 4265 orthologs revealed that the merged genomes were dominantly expressed in different ploidy hybrids. The differentially expressed genes in the two types of hybrids were asymmetric compared with those in both parents. Furthermore, the genome-wide expression level dominance (ELD) was biased toward the maternal BSB genome in both the allodiploid and triploid hybrids. In addition, the dosage-compensation mechanisms that reduced the triploid expression levels to the diploid state were determined in the triploid hybrids. Conclusions Our results indicate that divergent genomes undergo strong interactions and domination in allopolyploid offspring. Genomic merger has a greater effect on the gene-expression patterns than genomic doubling. The various expression mechanisms (including maternal effect and dosage compensation) in different ploidy hybrids suggest that the initial genomic merger and doubling play important roles in polyploidy adaptation and evolution.

Anisotropic bonded NdFeB permanent magnets have wide potential applications in the areas such as brushless DC motors, spindle motors, and stepping motors due to their excellent processing property and high magnetic properties. Anisotropic NdFeB bonded magnets prepared by hydrogen-disproportionation–desorption-recombination (HDDR) process have large energy product at room temperature. However, they are not stable at ∼100°C, which is the working temperature of many electric motors. In order to improve their thermal stability, we developed bonded NdFeB/SmCo magnets and investigated the effects of powder particle size and SmCo content on their magnetic properties. We proposed a model to clarify the filling effect of the powder, which played a key role in the enhanced (BH)max when reducing the SmCo particle size. As for the SmCo content, the bonded magnets showed improved (BH)max at 100°C-150°C and thermal stability with the increase of SmCo content. And through adjusting the SmCo content, the remanence temperature coefficient and coercivity temperature coefficient from 25-150°C were able to be regulated in the range of -0.14%/°C to -0.04%/°C and -0.51%/°C to -0.14%/°C, respectively. This work provides a design strategy and a facile route to improve the magnetic properties and thermal stability of the bonded magnets.

Based on the formation of an autotetraploid fish line (4nAUT, 4n = 200; F2–F11) derived from the distant hybridization of female Carassius auratus red var. (RCC, 2n = 100) × male Megalobrama amblycephala (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 Cyprinus carpio (CC, 2n = 100) with males of 4nAUT. The aim of this study was to comparatively investigate the reproductive characteristics of 3nALT and 3nAUT. We investigated morphological traits, chromosomal numbers, DNA content and gonadal development in 3nAUT and 3nALT. The results indicated both 3nAUT and 3nALT possessed 150 chromosomes and were triploid hybrids. The females and males of 3nALT and males of 3nAUT had abnormal gonadal development and could not generate mature eggs or sperm, but the females of 3nAUT had normal gonadal development and generated mature eggs at 2 years old. The females of 3nAUT generated different sizes of eggs, which fertilized with haploid sperm from RCC and formed viable diploid, triploid, and tetraploid offspring. The formation of these two kinds of triploid hybrids provides an ideal model for studying the reproductive traits of triploid hybrids, which is of great value in animal genetics and reproductive biology.

Polyploidization can significantly alter the size of animal gametes. Autotetraploid fish (RRRR, 4nRR = 200) (4nRR) possessing four sets of chromosomes were derived from whole-genome duplication in red crucian carp (RR, 2n = 100) (RCC). The diploid eggs of the 4nRR fish were significantly larger than the eggs of RCC. To explore the differences between the ovaries of these two ploidies of fishes at the molecular level, we compared the ovary transcriptome profiles of 4nRR fish and RCC and identified differentially expressed genes (DEGs). A total of 19,015 unigenes were differentially expressed between 4nRR fish and RCC, including 12,591 upregulated and 6,424 downregulated unigenes in 4nRR fish. Functional analyses revealed that eight genes (CDKL1, AHCY, ARHGEF3, TGFβ, WNT11, CYP27A, GDF7, and CKB) were involved in the regulation of cell proliferation, cell division, gene transcription, ovary development and energy metabolism, suggesting that these eight genes were related to egg size in 4nRR fish and RCC. We validated the expression levels of these eight DEGs in 4nRR fish and RCC using quantitative PCR. The study results provided insights into the regulatory mechanisms underlying the differences in crucian carp egg sizes.

In this study, the Ag3PO4/SnO2 heterojunction on carbon cloth (Ag3PO4/SnO2/CC) was successfully fabricated via a facile two-step process. The results showed that the Ag3PO4/SnO2/CC heterojunction exhibited a remarkable photocatalytic performance for the degradation of Rhodamine B (RhB) and methylene blue (MB), under visible light irradiation. The calculated k values for the degradation of RhB and MB over Ag3PO4/SnO2/CC are 0.04716 min−1 and 0.04916 min−1, which are higher than those calculated for the reactions over Ag3PO4/SnO2, Ag3PO4/CC and SnO2/CC, respectively. The enhanced photocatalytic activity could mainly be attributed to the improved separation efficiency of photogenerated electron-hole pairs, after the formation of the Ag3PO4/SnO2/CC heterojunction. Moreover, carbon cloth with a large specific surface area and excellent conductivity was used as the substrate, which helped to increase the contact area of dye solution with photocatalysts and the rapid transfer of photogenerated electrons. Notably, when compared with the powder catalyst, the catalysts supported on carbon cloth are easier to quickly recycle from the pollutant solution, thereby reducing the probability of recontamination.

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 (Megalobrama amblycephala, BSB, 2n = 48) and carnivorous topmouth culter (Culter alburnus, TC, 2n = 48). We investigated the genetic effects on gut microbiota assemblages by using 16S rRNA gene sequencing. The results showed that the gut characteristics (structure, relative gut length, relative gut mass, and Zihler’s index) differed between the two types of hybrids and the two parents. In particular, a strong correlation between genotype and gut microbial assemblages indicated that host genetic (subgenome) significantly altered the gut microbial communities. In addition, the microbial structures (composition and abundance) in the two types of hybrids were more similar to those in BSB parent (P > 0.05) than to those in TC parent (P < 0.05), and the cellulase contents in the gut (produced by gut microbes) also showed the similar results. The results suggested that the host genomic interaction (mainly subgenome domination) had a sizeable effect on shaping the gut microbiota assemblages in reciprocal hybrid fish. This study enriches our understanding of the relationship between host genetic and gut microbiota assemblages, and provides insight into gut microbiota and metabonomics.

The biological concentration effect of radionuclides in marine fish has exacerbated public anxiety about seafood security in the context of Fukushima nuclear-contaminated water discharged into the ocean. However, the most polluted port near the Fukushima Daiichi Nuclear Power Plant (FDNPP) has seldom been investigated, especially for radioactivity in marine fish. In this study, decadal observations of radiocesium in marine fish and seawater from the most polluted port were simultaneously established after the Fukushima Nuclear Accident. We found a generally decreasing trend of historical 137Cs activity in seawater, with seasonal variations modulated by precipitation. Seasonal variations were elucidated with finer detail and divided into exponential decline in the dry season and steady variation in the wet season. A novel method was proposed to estimate the continuing source term of 137Cs derived from the FDNPP, which was 3.9 PBq in 2011 and 19.3 TBq between 2012 and 2022 on the basis of historical 137Cs. The biological concentration effect of marine fish is quantitatively emphasized according to the higher ratio of over-standards for radiocesium in marine fish relative to that in seawater. Long-term observation and analysis of radiocesium in marine fish and seawater from the most polluted port would provide insights into the scientific evaluation of the effectiveness of the decommissioning of the FDNPP in the past and share lessons on the fate of Fukushima-derived radionuclides in the future.