Description of the complete rDNA repeat unit structure of Coturnixjaponica Temminck et Schlegel, 1849 (Aves).

Ribosomal RNA (18S, 5.8S, 28S) gene clusters in genomes form regions that consist of multiple tandem repeats. They are located on a single or several pairs of chromosomes and play an important role in the formation of the nucleolus responsible for the assembly of ribosome subunits. The rRNA gene cluster sequences are widely used for taxonomic studies, however at present, complete information on the avian rDNA repeat unit structure including intergenic spacer sequence is available only for the chicken (Gallusgallusdomesticus Linnaeus, 1758). The GC enrichment and high-order repeats peculiarities within the intergenic spacer described for the chicken rDNA cluster may be responsible for these failures. The karyotype of the Japanese quail (Coturnixjaponica Temminck et Schlegel, 1849) deserves close attention because, unlike most birds, it has three pairs of nucleolar organizer bearing chromosomes, two of which are microchromosomes enriched in repeating elements and heterochromatin that carry translocated terminal nucleolar organizers. Here we assembled and annotated the complete Japanese quail ribosomal gene cluster sequence of 21166 base pairs (GenBank under the registration tag BankIt2509210 CoturnixOK523374). This is the second deciphered avian rDNA cluster after the chicken. Despite the revealed high similarity with the chicken corresponding sequence, it has a number of specific features, which include a slightly lower degree of GC content and the presence of bendable elements in the content of both the transcribed spacer I and the non-transcribed intergenic spacer.

Effects of dietary digestible lysine levels in breeding Japanese quails on productive and reproductive performance, egg quality, blood metabolites and immune responses.

BACKGROUND: The vegetable-based diet alone does not provide the lysine (Lys) needed to maximize poultry productive performance. OBJECTIVES: This experiment aimed to evaluate the effects of dietary digestible Lys (dLys) level on productive and reproductive performance, egg quality, blood metabolites and immune responses in breeding Japanese quails (Coturnix japonica). METHODS: The experiment was conducted in a completely randomized design with 6 treatments, 5 replicates and 15 (12 females and 3 meals) 10-week-old breeding Japanese quails each. A basal diet was formulated to meet nutritional requirements of breeding quails except dLys. The basal diet was supplemented with graded (+0.82 g/kg) levels of l-Lys-HCl, corresponding to dietary dLys levels of 0.690%, 0.755%, 0.820%, 0.885%, 0.950% and 1.015%. The experiment lasted for 12 weeks, which was divided into 3-4-week periods. RESULTS: Significant differences were observed for egg production (EP), egg mass (EM) and feed efficiency (FE) in response to increasing dietary dLys concentration with quadratic trends. The highest traits were observed in the birds fed with a diet containing 0.885% dLys. However, feed intake, egg quality, reproductive performance, blood metabolites and immune responses against sheep red blood cell inoculation were not significantly affected by increasing dietary dLys concentrations. The dLys requirements during 11-14, 15-18, 19-22 and 11-22 (overall) weeks of age for optimal EP, EM and FE, based on the quadratic broken-line regression analysis, were estimated 272, 265, 250 and 266; 293, 285, 264 and 279; and 303, 294, 281 and 293 mg/bird/day, respectively. CONCLUSIONS: The dLys requirements vary depending on the EP phase and the trait being optimized. The estimated dLys requirement for FE was higher than those for EP and EM. During the peak stage of the first laying cycle, the dietary dLys level of 0.932% and a daily intake of 303 mg dLys/bird are sufficient for optimal performance.

Exploring neuronal markers and early social environment influence in divergent quail lines selected for social motivation.

Many species, including humans exhibit a wide range of social behaviors that are crucial for the adaptation and survival of most species. Brain organization and function are shaped by genetic and environmental factors, although their precise contributions have been relatively understudied in the context of artificial selection. We used divergent lines of quail selected on their high versus low level of motivation to approach a group of conspecifics (S + and S-, respectively) to investigate the influence of genetic selection and early social environment on sociability. We observed distinct sex- and brain-region-specific expression patterns of three neuronal markers: mesotocin, and vasotocin, the avian homologues of mammalian oxytocin and vasopressin, as well as aromatase, the enzyme that converts androgens into estrogens. These markers displayed pronounced and neuroanatomically specific differences between S + and S- quail. Additionally, in a second experiment, we assessed the influence of early social environment on social skills in juvenile birds. Mixing S + and S- resulted in more S- males approaching the group without affecting the sociability of S + or other behaviors, suggesting that the early social environment may influence the results of genetic selection. In conclusion, the divergent quail lines offer a valuable model for unraveling the neuronal and behavioral mechanisms underlying social behaviors.

Changes in performance, cecal microflora counts and intestinal histology of Japanese quails fed diets containing different fibre sources.

The purpose of this experiment was to investigate how various fiber sources impact the performance, microbial population, and intestinal histology of Japanese quail that was performed in a completely randomized design for 42 days. The dietary treatments involved a fiber-free corn-soybean meal-based diet (control, CTL), and CTL with added levels of sunflower hulls (SFH) and sugar beet pulp (SBP) (20 and 40 g kg-1). Body weight gain (BWG) and feed intake (FI) were recorded weekly. Carcass characteristics, cecal microbial population, blood variables and intestinal histology were measured on the 42 day of age. Adding 40 g kg-1 of SBP led to a significant decrease in body weight gain and an increase in the feed conversion ratio of birds from 1 to 21 days (P < 0.05). The relative weight of the gastrointestinal tract and gizzard increased significantly in birds that consumed SFH. Blood triglyceride concentration decreased with the inclusion of fiber in the diet. However, there was a notable increase in blood cholesterol concentration in the birds that were fed SBP (20 and 40 g kg-1) in comparison to those fed SFH (P < 0.05). The population of E. Coli in the cecum increased significantly in the birds that were fed 4 g kg-1 of SBP as opposed to those fed 20 and 40 g kg-1 of SFH (P < 0.05). The villus height of the jejunum in birds that were fed 20 g kg-1 and 40 g kg-1 of SFH demonstrated a significant increase in comparison to the other treatments (P < 0.05). In general, the findings of this research indicated that the inclusion of 40 g kg-1 of SBP in the diet had a negative impact on performance and other physiological parameters. However, the use of SFH and 20 g kg-1 of SBP yielded similar results to birds in the CTL, and in some cases, even better outcomes.

Early-life group size influences response inhibition, but not the learning of it, in Japanese quails.

In complex social environments, animals benefit from suppressing inappropriate responses (known as Response Inhibition) to avoid conflicts and maintain group cohesion. Recent research suggests that an individual's early-life social environment can shape their response inhibition. However, these findings have mostly been correlational, and results vary across species. Furthermore, the role of learning is often overlooked when measuring response inhibition, despite its potential importance to understanding group differences. We investigated the effect of early-life group size, a key determinant of social complexity, on response inhibition in Japanese quails (Coturnix japonica), whilst taking the role of learning into account. Quails (n = 120) were raised in either small groups of five or large groups of 15 individuals. Response inhibition was assessed using the cylinder task. Up to ten trials were administered to assess whether the birds' responses changed with increasing experience of the task. Among the quails that completed ten trials, we found that those raised in large groups consistently spent less time pecking the cylinder than those raised in small groups. The quails' responses were also influenced by their body condition, food motivation and sex. Importantly, the quails learned to inhibit their responses - successful trials increased, and time spent pecking the cylinder decreased, across ten trials. However, learning rates did not differ between the treatment groups. These findings suggest that early-life social group size promotes the development of response inhibition in quails, but not their learning of it, during the cylinder task.

Maternal stress effects across generations in a precocial bird.

Prenatal maternal stress (PMS) is known to shape the phenotype of the first generation offspring (F1) but according to some studies, it could also shape the phenotype of the offspring of the following generations. We previously showed in the Japanese quail that PMS increased the emotional reactivity of F1 offspring in relation to (i) a variation in the levels of some histone post-translational modification (H3K27me3) in their brains and (ii) a modulation of the hormonal composition of the eggs from which they hatched. Here, we wondered whether PMS could also influence the behaviour of the second (F2) and third (F3) generation offspring due to the persistence of the specific marks we identified. Using a principal component analysis, we found that PMS influenced F2 and F3 quail profiles with subtle differences between generations. It increased F2 neophobia, F3 fearfulness and F3 neophobia but only in females. Interestingly, we did not find any variations in the level of histone post-translational modification in F3 brains and we observed inconsistent modulations of androstenedione levels in F1 and F2 eggs. Although they may vary over generations, our results demonstrate that PMS can have phenotypical effects into the third generation.

Ovomucoid gene polymorphism and its influence on quality changes at various storage timepoint of eggs from two strains of Japanese quail.

During storage, irreversible changes occur in eggs, resulting in a decline in their quality, predominantly affecting the albumen. Ovomucoid, a major protein found in egg white, belongs to the Kazal-type serine proteinase inhibitors and serves to protect the embryo from microorganisms. Notably, in chicken eggs, it is a significant allergen. There is a possibility that its polymorphism also influences the quality and stability of table eggs. Hence, this study aimed to evaluate the potential effect of polymorphism in the ovomucoid gene and protein on quality changes during the storage of eggs derived from 2 strains of Japanese quail, encompassing various utility types. Eggs from selected females of laying and meat-type breeds were stored for 14 wk, with egg quality traits assessed 10 times during this duration. DNA was isolated from each female, and sequencing was conducted on all exons of the ovomucoid gene. In total, 5 SNPs were identified in exons and adjacent intronic sequences, with SNP1 (13:12355585), SNP4 (13:12356594), and SNP5 (13:12358538) leading to amino acid substitutions in the ovomucoid protein. Notably, all SNPs except SNP5 were identified in the ovomucoid gene of Japanese quail for the first time. The results demonstrated that in the F33 strain, SNP1, SNP3, and SNP4 exhibited significant associations with egg weight, whereas in the S22 strain, SNP5 significantly affected yolk color and various eggshell quality traits, including eggshell weight, eggshell thickness, and breaking strength, throughout the storage period. Furthermore, a haplotype block containing 2 SNPs (3 and 4) was identified, exhibiting 2 distinct haplotypes that significantly affected egg weight, eggshell weight, and breaking strength at various storage time points during egg quality analyses. These findings provide novel insights into the genetic basis of egg quality during storage and have the potential to be integrated into breeding programs for these strains.

RNA sequencing analysis of sexual dimorphism in Japanese quail.

Introduction: Japanese quail are of significant economic value, providing protein nutrition to humans through their reproductive activity; however, sexual dimorphism in this species remains relatively unexplored compared with other model species. Method: A total of 114 RNA sequencing datasets (18 and 96 samples for quail and chicken, respectively) were collected from existing studies to gain a comprehensive understanding of sexual dimorphism in quail. Cross-species integrated analyses were performed with transcriptome data from evolutionarily close chickens to identify sex-biased genes in the embryonic, adult brain, and gonadal tissues. Results: Our findings indicate that the expression patterns of genes involved in sex-determination mechanisms during embryonic development, as well as those of most sex-biased genes in the adult brain and gonads, are identical between quails and chickens. Similar to most birds with a ZW sex determination system, quails lacked global dosage compensation for the Z chromosome, resulting in directional outcomes that supported the hypothesis that sex is determined by the individual dosage of Z-chromosomal genes, including long non-coding RNAs located in the male hypermethylated region. Furthermore, genes, such as WNT4 and VIP, reversed their sex-biased patterns at different points in embryonic development and/or in different adult tissues, suggesting a potential hurdle in breeding and transgenic experiments involving avian sex-related traits. Discussion: The findings of this study are expected to enhance our understanding of sexual dimorphism in birds and subsequently facilitate insights into the field of breeding and transgenesis of sex-related traits that economically benefit humans.

Initial formation of and sex differences in primordial germ cells in Japanese quail.

DEAD-box RNA helicase 4 (DDX4) is posited to be a key maternal germ cell factor regulating avian germ cell formation. We herein showed that the DDX4 gene product of zygotic genome activation associated with the nuclear localization of the cyclin D1 protein in presumptive primordial germ cells (PGCs) plays an essential role in the proliferation of PGCs using a CRISPR/Cas9 system approach combined with in vitro fertilization techniques in Japanese quail. A proteome analysis also revealed molecular-based differences in the features of early male and female PGCs.

The influence of dietary supplementation with fermented agro-industrial residue of faba bean on Japanese quail performance, immunity, gut microbiota, blood chemistry, and antioxidant status.

Antibiotic overuse in poultry feeds has disastrous implications; consequently, long-term alternatives must be developed. As a result, the current study aims to assess the impact of Aspergillus niger filtrate (ANF) high in organic acids grown on agro-industrial residue of faba bean (AIRFB) on quail diet, as well as their influence on bird productivity, digestion, carcass yield, blood chemistry, and intestinal microbiota. A total of 240 Japanese quails (aged 7 d) were used in this study, divided equally among 5 experimental groups with 48 quails each. Group 1 (G1) received a basal diet without any ANF, group 2 (G2) received a basal diet supplemented with 0.5 mL ANF/kg diet, group 3 (G3) received a basal diet supplemented with 1.0 mL ANF/kg diet, group 4 (G4) received a basal diet supplemented with 1.5 mL ANF/kg diet, and group 5 (G5) received a basal diet supplemented with 2 mL ANF/kg diet. The performance parameters were monitored at 1 to 3, 3 to 5, and 1 to 5 wk. Adding ANF increased body weight at 3 and 5 wk, as well as body weight gain at 1 to 3, 3 to 5, and 1 to 5 wk, compared to the control diet. The ANF fed quails had the highest feed conversion ratio compared to the control group. The addition of ANF to the quail diet had no effect on the weight of the carcass, gizzard, heart, liver, giblets, or dressing; however, it did lower triglycerides, low-density lipoprotein, and very low-density lipoprotein while increasing high-density lipoprotein levels. The quail groups that received ANF had enhanced immunological indices such as IgG, IgM, IgA, and lysozymes. It also increased the levels of superoxide dismutase and total antioxidant contents, as well as catalase, and digestive enzymes such as protease, amylase, and lipase. However, it lowered the blood MDA levels compared to control. It has been demonstrated that the total gut microbiota, Escherichia coli, total coliforms, and the population of Salmonella are all reduced in ANF-fed quails. Histological examination of ANF quails' liver and intestinal sections revealed normal hepatic parenchyma, typical leaf-like intestinal villi, and comparatively short and frequently free lumina. In conclusion, Japanese quail showed improvements in performance, digestive enzymes, antioxidant indices, immunity, and capacity to reduce intestinal pathogenic bacteria after consuming diet supplemented with ANF.

Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid.

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

The relationship of the male's proctodeal gland size to sperm-egg interaction and the duration of fertility in Japanese quail.

In avian species, male fertility significantly impacts reproductive success. This study investigates the relationship between proctodeal gland size in male Japanese quails and sperm function, as well as female fertility duration. Six hundred adult Japanese quails were selected and housed in individual cages. Males (n = 300) were divided into 6 groups (50/group) based on the size of their proctodeal glands. Females (n = 300) were randomly assigned to corresponding groups. After acclimatization, sperm kinematics and the frequency and weight of foam discharge were evaluated. Males were paired with females for 24 h, and eggs were collected for 20 d postcopulation. Eggs were incubated to assess fertility duration. Fresh eggs (n = 20/group/d) were used to assess sperm penetration into the perivitelline membrane on the 2nd, 9th, and 16th d postinsemination. Plasma testosterone levels and the testes' relative weight were determined. The results indicated a significant increase (p < 0.0001) in sperm concentration, total and progressive motility, and nearly all sperm kinematic parameters such as VSL, VCL, VAP, LIN, WOB, and STR values as the size of the proctodeal gland increased. Quails copulated with males having a small and average proctodeal gland area (<400 mm2) laid fertile eggs for a shorter period and had significantly fewer sperm penetration holes than those mated with males having a larger proctodeal gland area (>400 mm2). The proctodeal gland size was positively correlated with testicular weight, plasma testosterone concentrations, and sperm kinetic variables. The results indicate that the size of the proctodeal gland in males can be used to predict sperm function and the duration of fertility in Japanese quail.

Effects of immersing Japanese quail eggs in various doses of riboflavin on reproductive, growth performance traits, blood indices and economics.

This investigation aimed to evaluate the impact of immersion (IM) riboflavin treatment on the hatchability, production efficiency, and carcass characteristics of Japanese quail eggs. A total of 260 eggs of Japanese quail birds were used for hatching and were randomly divided into 4 treatments with 5 replicates (13 eggs/replicate) in a fully randomized design. Hatching eggs were immersed in riboflavin for 2 min before incubation. The experiment treatments were designed as follows: G1 control group with no treatment, G2 treated with 3 g/L vit. B2 (IM), G3 treated with 4 g/L vit. B2 (IM) and G4 were treated with 5 g/L vit. B2 (IM). After hatching, 128 Japanese quail chicks, aged 7 d, were randomly grouped into 4 treatment groups, with 32 birds in each group. When quails were given vitamin B2 via immersion, they demonstrated significant enhancements in live body weight, body weight gain, feed consumption, and feed conversion ratio at different stages compared to the control group. Compared to control and other groups, the carcass parameters of Japanese quails given a 4 g/L immersion solution showed a significant improvement (P < 0.05). Hatchability and fertility (%) were considerably raised by Vit.B2 treatments of 3, 4, and 5g; the group immersed in 5 g/L had the highest percentages compared to the other groups. Furthermore, treated chickens with all concentrations of vitamin B2 had significantly higher blood indices than the controls. During the exploratory phase (1-6 wk) of age, the highest returns were reported in G4 treated with 5g/L vit. B2 (IM). Treating Japanese quail eggs with different dosages of vitamin B2 by immersion may be recommended to improve their productive and reproductive performance, blood indices, carcass traits, and economic efficiency.

The relationship between lysozyme gene polymorphism and quality changes during the storage of eggs derived from 2 commercial strains of Japanese quail.

During the storage irreversible changes occur in eggs that result in a deterioration of their quality. The most significant changes affect the albumen. One of the major proteins of albumen present in egg white is lysozyme, which protects the embryo from microorganisms. This enzyme also contributes to the qualitative characteristics of albumen. It is possible that its polymorphism also affects the quality and stability of the obtained raw material that is, table eggs. Therefore, the aim of this study was to assess the potential effect of polymorphism in the lysozyme gene and protein on the quality changes during the storage of eggs derived from 2 genetic strains of Japanese quail belonging to various utility types. Eggs from selected females of laying and meat-type breeds were stored for 14 wk. During this period the egg quality traits were evaluated 10 times. DNA was isolated from each female and all exons of the lysozyme gene had been sequenced. In total, fourteen SNPs' and one 4-bp indel mutation were identified in exons and adjacent intronic sequences, among which SNP1 (1:32140723) resulted in a substitution of lysine with glutamine (Q21K). The results showed that SNP1 (strain S22), as well as the SNP2, SNP5, SNP7, SNP8, SNP10, SNP11, SNP12 and SNP13 were significantly associated with breaking strength during egg storage in both investigated Japanese quail strains. Furthermore, a 3 haplotype blocks containing nine SNPs (2, 5, 6, 7, 8, 10, 11, 12 and 13) were identified. These blocks displayed 8 distinct haplotypes that had significant association with breaking strength at all storage time points where egg quality analyses were performed. The study also revealed significant effects of breed and storage time on the egg quality traits. These results provide new insights into the genetic basis of egg quality during storage and could be incorporated into the breeding programs involving these strains.

Carcass characteristics, physicochemical traits, texture and microstructure of young and spent quails meat.

The purpose of the study was to compare young (6-wk-old) and spent (52-wk-old) Japanese quail in terms of body weight, carcass characteristics, and some meat quality traits. Whole carcasses were dissected, pectoral muscles and leg muscles were sampled for determination of basic chemical composition and L*a*b* color parameters, while m. pectoralis major was sampled for texture and microstructure traits. Age of quails had a significant effect on body weight, carcass weight, carcass yield, pectoral muscle, abdominal fat and skin with subcutaneous fat, and carcass remainders contents in eviscerated carcass. Spent quails had significantly higher intramuscular fat content in pectoral and leg muscles and protein content in breast muscle, and also lower content of water in breast and leg muscles than young quails. Slaughter age significantly affected lightness (L*) and redness (a*) of pectoral muscles, as well as texture traits (except for cohesiveness) and microstructure of m. pectoralis major, except for thickness of perimysium and endomysium. Regardless of age, quail sex had an effect on the carcass traits studied (except for leg muscle content), intramuscular fat content of pectoral and leg muscles, water content of leg muscles and yellowness of pectoral muscle. In addition, a significant effect of quail sex was found on cutting work, springiness, chewiness and marked microstructural characteristics, except for vertical fiber diameter. The interaction between age and sex was significant for most slaughter and microstructural characteristics and also WB-shear force of m. pectoralis major, and L*, b* pectoral muscles. Higher fatness of carcasses, higher intramuscular fat in meat, and poorer textural and microstructural characteristics of m. pectoralis major spent Japanese quail indicate poorer fulfillment of most consumers' requirements compared to carcasses and meat of young quails.

The impacts of dietary inclusion of soybean oil and linseed oil on growth performance, carcass yield, and health status of growing Japanese quail.

Polyunsaturated fatty acids (PUFA), including n-6 and n-3 fatty acids, are essential for enhancing the performance and health of poultry. Avian species lack desaturase enzymes for endogenous synthesis of n-6 and n-3 fatty acids. This work aimed to determine the impacts of including soybean oil (SO) and linseed oil (LO) in quail diets on growth, lipid profile, hepatic and renal functions, immunity, and antioxidant status. A total of 350 Japanese quail chicks (1-wk-old) were randomly arranged into 7 dietary treatment groups. Seven isocaloric and isonitrogenous experimental basal diets were formed based on the nutritional requirements of growing Japanese quail. Group 1, the control, received a basal with no oils, while groups 2 to 7 received a basal diet containing either 1% SO, 1.5% SO, 2% SO, 1% LO, 1.5% LO, or 2% LO, respectively. Quail groups that consumed diets containing LO at all levels showed significantly greater live body weight (LBW) at 5th wk of age than other experimental groups. The dietary incorporation of 1.5 or 2% SO or LO at all levels yielded significant improvements in body weight gain (BWG) and feed conversion ratio (FCR) through 3 to 5 and 1 to 5 wk of age. Different dietary oil sources and levels have no significant impacts on feed intake (FI) and carcass yield parameters. Lipid profile parameters were improved by adding SO and LO in quail diets, with LO having a higher effect than SO. The hepatic and renal functionality were improved by adding SO and LO in quail diets. The lowest uric acid (UA) bloodstream concentrations were recorded in the quail group fed a diet with 2% LO. Values of Gamma globulins (G-GLO) and immunoglobulins (G, M, and A) were increased by adding SO or LO to quail diets. Blood levels of MDA and TAC were improved significantly by including LO in quail diets. The activity of the superoxide dismutase (SOD) enzyme was significantly increased by adding SO or LO to quail diets. Generally, adding SO or LO to growing quail diets up to 2% could yield favorable effects on growth performance, blood lipids, hepatic and renal functions, immunity, and antioxidant status; however, LO seems to have better effects than SO.

Evaluation of biological selenium nanoparticles on growth performance, histopathology of vital organs and genotoxicity in Japanese quails (coturnix coturnix japonica).

Research on the effects of selenium nanoparticles (Se-NPs), particularly in Japanese quails, is lacking, especially regarding the potential for DNA damage. Therefore, this study aimed to investigate the impact of administering 0.2 and 0.4 mg/kg of Se-NPs on the growth performance, DNA integrity, and histopathological alterations of the liver, lung, kidney, and heart in quails. A total of 480 one-day-old Japanese quails were divided into three experimental groups as follows: Group 1 served as the control and received only basic feed, while Group 2 and 3 received 0.2 mg/kg and 0.4 mg/kg of Se-NPs via oral gavage. Our results suggested that, birds fed with Se-NPs at both levels significantly (p < .01) reduced feed intake, however, weight gain was significantly (p < .01) increased in quails supplemented with 0.2 mg/kg. Similarly, feed conversion ratio (FCR) was significantly (p < .01) reduced in group supplemented with 0.2 mg/kg Se-NPs. White blood cells increased significantly (P0.01) in 0.4 mg/kg while haemoglobin and red cell distribution width decreased (p < .01) in the same group. Both treatment regimens resulted in DNA damage and histopathological alterations; however, the adverse effects were more prominent in the group receiving the higher dose of 0.4 mg/kg. These findings indicate that the lower dose of 0.2 mg/kg may have beneficial effects on growth. However, the higher dose of 0.4 mg/kg not only negatively impacts growth but also leads to histopathological alterations in major organs of the body and DNA damage as well.

Expression of mRNAs Encoding Hypothalamic Small Proteins, Neurosecretory Protein GL and Neurosecretory Protein GM, in the Japanese Quail, Coturnix japonica.

Neurosecretory protein GL (NPGL) and neurosecretory protein GM (NPGM) are novel neuropeptides that have been discovered in the hypothalamic infundibulum of chickens. NPGL and NPGM play important roles in lipid metabolism in juvenile chickens. The physiological functions of NPGL and NPGM in sexually mature birds remain unknown. The Japanese quail (Coturnix japonica) seems to be an appropriate model for analyzing NPGL and NPGM during sexual maturity. However, studies on NPGL or NPGM have yet to be reported in the Japanese quail. In the present study, we identified cDNAs encoding precursor proteins of NPGL and NPGM in the quail hypothalamus. In situ hybridization revealed that NPGL mRNA-expressing cells in the hypothalamus were localized in the infundibular nucleus and median eminence, and NPGM mRNA-expressing cells were only found in the mammillary nucleus. Immunohistochemistry revealed that NPGM-like immunoreactive cells were distributed in the mammillary nucleus, whereas NPGL-like immunoreactive cells were not detected in the hypothalamus. Real-time PCR analysis indicated that the expression of NPGL mRNA was higher in the hypothalamus of females than in that of males, and NPGM mRNA expression showed no sex differences. NPGL and NPGM mRNA expression in males was upregulated after 24 h of food deprivation. In females, only NPGM mRNA expression was increased by fasting. These results suggest that the physiological functions of NPGL and NPGM are different in quail, and these factors are involved in sex differences in energy metabolism.

Genome-Wide Association Study Revealed Putative SNPs and Candidate Genes Associated with Growth and Meat Traits in Japanese Quail.

The search for SNPs and candidate genes that determine the manifestation of major selected traits is one crucial objective for genomic selection aimed at increasing poultry production efficiency. Here, we report a genome-wide association study (GWAS) for traits characterizing meat performance in the domestic quail. A total of 146 males from an F2 reference population resulting from crossing a fast (Japanese) and a slow (Texas White) growing breed were examined. Using the genotyping-by-sequencing technique, genomic data were obtained for 115,743 SNPs (92,618 SNPs after quality control) that were employed in this GWAS. The results identified significant SNPs associated with the following traits at 8 weeks of age: body weight (nine SNPs), daily body weight gain (eight SNPs), dressed weight (33 SNPs), and weights of breast (18 SNPs), thigh (eight SNPs), and drumstick (three SNPs). Also, 12 SNPs and five candidate genes (GNAL, DNAJC6, LEPR, SPAG9, and SLC27A4) shared associations with three or more traits. These findings are consistent with the understanding of the genetic complexity of body weight-related traits in quail. The identified SNPs and genes can be used in effective quail breeding as molecular genetic markers for growth and meat characteristics for the purpose of genetic improvement.

Ethynylestradiol feminizes gene expression partly in testis developing as ovotestis and disrupts asymmetric Müllerian duct development by eliminating asymmetric gene expression in Japanese quail embryos.

In avian embryos, xenoestrogens induce abnormalities in reproductive organs, particularly the testes and Müllerian ducts (MDs). However, the molecular mechanisms remain poorly understood. We investigated the effects of ethynylestradiol (EE2) exposure on gene expression associated with reproductive organ development in Japanese quail embryos. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis revealed that the left testis containing ovary-like tissues following EE2 exposure highly expressed the genes for steroidogenic enzymes (P450scc, P45017α, lyase, and 3ß-HSD) and estrogen receptor-ß, compared to the right testis. No asymmetry was found in these gene expression without EE2. EE2 induced hypertrophy in female MDs and suppressed atrophy in male MDs on both sides. RNA sequencing analysis of female MDs showed 1,366 differentially expressed genes between developing left MD and atrophied right MD in the absence of EE2, and these genes were enriched in Gene Ontology terms related to organogenesis, including cell proliferation, migration and differentiation, and angiogenesis. However, EE2 reduced asymmetrically expressed genes to 21. RT-qPCR analysis indicated that genes promoting cell cycle progression and oncogenesis were more highly expressed in the left MD than in the right MD, but EE2 eliminated such asymmetric gene expression by increasing levels on the right side. EE2-exposed males showed overexpression of these genes in both MDs. This study reveals part of the molecular basis of xenoestrogen-induced abnormalities in avian reproductive organs, where EE2 may partly feminize gene expression in the left testis, developing as the ovotestis, and induce bilateral MD malformation by canceling asymmetric gene expression underlying MD development.