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.

Elevated temperature affects the expression of signaling molecules in quail testes meiosis I prophase, but spermatogenesis remains normal.

Spermatogenesis in eukaryotes is a process that occurs within a very narrow temperature threshold, typically not exceeding 36 °C. SPO11 was isolated from the temperature-sensitive mutant receptor of Saccharomyces cerevisiae and is thought to be the only protein that functions during meiosis. This suggested that SPO11 may be the key protein that influenced the temperature of spermatogenesis not exceeding 36 °C. Elevated temperatures typically damage the spermatogenic cells. Birds have a core body temperature of 41-42 °C, and their testis are located inside their bodies, providing an alternative perspective to investigate the potential impact of temperature threshold on spermatogenesis. The objective of this study was to ascertain whether elevated ambient temperatures affect spermatogenesis in birds and whether SPO11 is the key gene affecting the temperature threshold for spermatogenesis. STRA8, SCP3, SPO11, γ-H2AX, and RAD51 were all crucial components in the process of meiotic initiation, synapsis, DNA double-strand break (DSB) induction, homologous chromosome crossover recombination, and repair of DSB. In this study, 39-day-old Japanese quail were subjected to heat stress (HS) at 38 °C for 8 h per day for 3 (3d HS) and 13 (13d HS) consecutive days and analyzed the expression of meiotic signaling molecules (STRA8, SCP3, SPO11, γ-H2AX, and RAD51) using molecular biology techniques, including Immunohistochemistry (IHC), Western Blot (WB), and Real-time Quantitative Polymerase Chain Reaction (qRT-PCR). We found that spermatogenesis was normal in both groups exposed to HS. Meiotic signaling molecules were expressed normally in the 3d HS group. All detected signaling molecules were normally expressed in the 13d HS group, except for SPO11, which showed a significant increase in expression, indicating that SPO11 was temperature-sensitive. We examined the localized expression of each meiotic signaling molecule in quail testis, explored the temperature sensitivity of SPO11, and determined that quail testis can undergo normal spermatogenesis at ambient temperatures exceeding 36 °C. This study concluded that SPO11 is not the key protein influencing spermatogenesis in birds. These findings enhance our understanding of avian spermatogenesis.

Increased nanosphere size in the cuticle layer of Japanese quail egg by mutation in the myostatin gene.

Cuticle quality can affect food safety by protecting poultry eggs from bacterial infection in the modern poultry industry. However, genetic factors related to cuticle nanostructure are not much reported due to limited bird models. In the current study, the genome-edited quail targeting myostatin (MSTN) gene was used to investigate the effect of MSTN mutation on the cuticle nanostructure and quality. To analyze nanostructure of the cuticle layer of the MSTN mutant and wild-type (WT) quail eggs, scanning electron microscope (SEM) images was taken. Thickness of the cuticle layer did not differ between the MSTN mutant and WT groups, but the size of the nanospheres in the surface of the cuticle layer was increased by MSTN mutation. In addition, increased size of the nanospheres in the MSTN mutant group was also shown in the upper region of the cross-sectional cuticle layer. Notably, both groups showed similar small-sized nanospheres in the lower region of the cuticle layer and the size was increased as they ascended to the upper region. The data suggested that MSTN mutation increased the size of the nanosphere in the upper region of the cuticle layer at a late phase rather than increasing the size of nanospheres in the lower region of the cuticle layer at an early phase of cuticle formation. However, the number of Escherichia coli attached to the surface did not differ between the two groups indicating no association between nanosphere size and bacterial attachment in quail eggs. The current study demonstrated a new function of the MSTN gene on regulation of cuticle nanostructure, for the first time. These results advanced our knowledge on the association between genetic factors and cuticle nanostructure and can be served as a reference to study the mechanism of cuticle formation in the future study.

The influence of genotype and sex on carcass composition, meat quality, digestive system morphometry and leg bone dimensions in Japanese quails (C. coturnix japonica).

Japanese quails (Coturnix japonica) have a high reproductive rate because they reach sexual maturity very early. This short rearing time results in increasing interest among breeders and consumers. The aim of the study was a comparative analysis of two genotypes and sexes of Japanese and Pharaoh quails and their impact on body weight, carcass composition, meat quality, digestive system morphometry and leg bone dimensions. The study involved 40 birds (10 females and 10 males), Japanese quail and Pharaoh quail, 42 days old. Quail genotype had an effect (P < 0.05) on body weight, carcass weight, and some percentage of carcass elements. In addition, there was a significant effect of quail genotype on intramuscular fat and water content of pectoral and leg muscles. The origin of the quails interacted (P < 0.05) with the lightness (L*), yellowness (b*), cutting work, hardness, springiness, chewiness, gumminess, fibre cross-sectional area, vertical fibre diameter, and perimysium thickness of pectoral muscle. In addition, genotype was found to influence some anatomical traits, such as the percentage of proventriculus, heart, and liver on body weight, lengths and diameters of duodenum, caeca, and colon, and most dimensions of leg bones (femur and tibia). The sex of the birds significantly (P < 0.05) affected body weight, carcass weight, percentage of skin with subcutaneous fat in the carcass, as well as water content, lightness (L*), and springiness, most microstructure characteristics of pectoralis muscle, and also water and protein contents, and yellowness (b*) of leg muscles. In addition, differences were found between males and females (P < 0.05) in terms of duodenum and caeca diameter, length of greatest and medial femur, and greatest length of tibia. It can be stated that in terms of body weight and carcass weight as well as some meat quality features (protein content, fat content, fiber cross-sectional area), the pharaoh quail was the better genotype, while in terms of the proportion of muscles in the carcass and selected meat quality features: hardness, gumminess, chewiness, Japanese quails turned out to be better.

Effects of female-specific selection for reproductive investment on male fertility traits.

Despite sharing an autosomal genome, the often divergent reproductive strategies of males and females cause the selection to act in a sex-specific manner. Selection acting on one sex can have negative, positive, or neutral fitness consequences on the opposite sex. Here, we test how female-limited selection on reproductive investment in Japanese quail (Coturnix japonica) affects male fertility-related traits. Despite there being no difference in the size of males' testes from lines selected for high female reproductive investment (H-line) or low female reproductive investment (L-line), in both lines, the left testis had a greater volume of sperm-producing tissue. Since H-line females have a larger left-side restricted oviduct, this suggests a positive genetic correlation between male and female gonad function and that internal testis structure is a target of sexual selection. However, despite H-line males having previously been found to have greater fertilization success in a competitive scenario, we found little evidence of a difference between the lines in sperm number, motility, velocity, length, or the number of sperm that reached the ova. Precopulatory cues and/or the role of seminal fluid in sperm motility may thus be more likely to contribute to the H-line male fertilization advantage in this species.

Mitogenomic Insights into the Evolution, Divergence Time, and Ancestral Ranges of Coturnix Quails.

The Old-World quails, Coturnix coturnix (common quail) and Coturnix japonica (Japanese quail), are morphologically similar yet occupy distinct geographic ranges. This study aimed to elucidate their evolutionary trajectory and ancestral distribution patterns through a thorough analysis of their mitochondrial genomes. Mitogenomic analysis revealed high structural conservation, identical translational mechanisms, and similar evolutionary pressures in both species. Selection analysis revealed significant evidence of positive selection across the Coturnix lineage for the nad4 gene tree owing to environmental changes and acclimatization requirements during its evolutionary history. Divergence time estimations imply that diversification among Coturnix species occurred in the mid-Miocene (13.89 Ma), and their current distributions were primarily shaped by dispersal rather than global vicariance events. Phylogenetic analysis indicates a close relationship between C. coturnix and C. japonica, with divergence estimated at 2.25 Ma during the Pleistocene epoch. Ancestral range reconstructions indicate that the ancestors of the Coturnix clade were distributed over the Oriental region. C. coturnix subsequently dispersed to Eurasia and Africa, and C. japonica to eastern Asia. We hypothesize that the current geographic distributions of C. coturnix and C. japonica result from their unique dispersal strategies, developed to evade interspecific territoriality and influenced by the Tibetan Plateau's geographic constraints. This study advances our understanding of the biogeographic and evolutionary processes leading to the diversification of C. coturnix and C. japonica, laying important groundwork for further research on this genus.

Research Note: Sexual dimorphic effect of myostatin mutation on fat accumulation in Japanese quail.

As an anti-myogenic factor, the myostatin (MSTN) gene was mainly considered as a genetic marker to improve meat production. Moreover, an additional effect of the MSTN mutation on reducing fat deposition in various farm animals suggested a potential application of the MSTN gene on regulating fat deposition in poultry species. Although increase in muscle mass resulted from muscle hyperplasia in the MSTN mutant quail, cellular mechanism behind the decrease in fat deposition was not investigated in the quail model. In the current study, to investigate sexual dimorphic association between fat deposition and Mstn mutation in quail, leg and abdominal fat pads from 4-month-old male and female quail were histologically analyzed. Interestingly, abdominal and leg fat pad weights were significantly decreased by the MSTN mutation only in female quail, but not in male quail, showing sexual dimorphism in regulating fat deposition by the MSTN mutation in quail. Histological analysis also revealed that fat cell sizes of leg and abdominal fats were significantly reduced only in female groups aligning with the decreased fat pad weights. Sexual dimorphic effect of the MSTN mutation on fat cell hypotrophy and reduced fat pad weights in quail provided an important scientific finding to be considered on the usage of the MSTN gene as a genetic marker to reduce fat deposition in poultry species.

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.

Does the marketing age impact growth performance, carcass traits, economic feasibility and hemato-biochemical properties of genetically-modified quails?

The meat of the quail is one of the most delicious types, as it is rich in minerals and vitamins, especially vitamin K, which is useful in treating nervous diseases. In the present investigation, based on their live body weight, 270 genetically-enhanced white quail chicks of mixed sex were randomly assigned to 3 groups, each with 90 chicks. The first group's birds were slaughtered at 28 d of age. The birds in the second group were slaughtered at 31 d, and the birds in the third group were slaughtered at 34 d. Results showed no significant difference between the various groups in the overall mortality rate index at the end of each fattening stage (P > 0.05). There were substantial variations (P ≤ 0.05) in the average live weight index between the first and both groups at each group's marketing age. With increasing marketing age, body weight increases. Quail chicks raised for 34 d received the lowest EPEF (28.90 points), followed by those raised for 31 d and 28 d, which received 33.37 and 37.32 points, respectively. The economic feasibility of the 3 groups, no significant differences in the profit index were observed at the age of 28 d. Compared to the marketing age of the other 2 groups, it was noted that the profit index decreased as the birds advanced in age. Delaying marketing to 31 d leads to a decrease in profit by 5.7%, and delaying marketing to 34 d reduces the profit index to 26.36% compared to marketing at 28 d. For blood hematology parameters, a significant increase in the studied indicators with the age of the birds was observed through the study of blood indicators. Still, it did not reach the significance level. It could be concluded that 28 d is the ideal marketing age for the enhanced white quails, as it yielded the highest economic return and the best performance.

Pre-natal exposure to glucocorticoids causes changes in developmental circadian clock gene expression and post-natal behaviour in the Japanese quail.

The embryonic environment is critical in shaping developmental trajectories and consequently post-natal phenotypes. Exposure to elevated stress hormones during this developmental stage is known to alter a variety of post-natal phenotypic traits, and it has been suggested that pre-natal stress can have long term effects on the circadian rhythm of glucocorticoid hormone production. Despite the importance of the circadian system, the potential impact of developmental glucocorticoid exposure on circadian clock genes, has not yet been fully explored. Here, we showed that pre-natal exposure to corticosterone (CORT, a key glucocorticoid) resulted in a significant upregulation of two key hypothalamic circadian clock genes during the embryonic period in the Japanese quail (Coturnix japonica). Altered expression was still present 10 days into post-natal life for both genes, but then disappeared by post-natal day 28. At post-natal day 28, however, diel rhythms of eating and resting were influenced by exposure to pre-natal CORT. Males exposed to pre-natal CORT featured an earlier acrophase, alongside spending a higher proportion of time feeding. Females exposed to pre-natal CORT featured a less pronounced shift in acrophase and spent less time eating. Both males and females exposed to pre-natal CORT spent less time inactive during the day. Pre-natal CORT males appeared to feature a delay in peak activity levels. Our novel data suggest that these circadian clock genes and aspects of diurnal behaviours are highly susceptible to glucocorticoid disruption during embryonic development, and these effects are persistent across developmental stages, at least into early post-natal life.

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.

Quail GHRL and LEAP2 gene cloning, polymorphism detection, phylogenetic analysis, tissue expression profiling and its association analysis with feed intake.

The GHRL, LEAP2, and GHSR system have recently been identified as important regulators of feed intake in mammals and chickens. However, the complete cloning of the quail GHRL (qGHRL) and quail LEAP2 (qLEAP2) genes, as well as their association with feed intake, remains unclear. This study cloned the entire qGHRL and qLEAP2 cDNA sequence in Chinese yellow quail (Coturnix japonica), including the 5' and 3' untranslated regions. Sanger sequencing analysis revealed no missense mutations in the coding region of qGHRL and qLEAP2. Subsequently, phylogenetic analysis and protein homology alignment were conducted on the qGHRL and qLEAP2 in major poultry species. The findings of this research indicated that the qGHRL and qLEAP2 sequences exhibit a high degree of similarity with those of chicken and turkey. Specifically, the N-terminal 6 amino acids of GHRL mature peptides and all the mature peptide sequence of LEAP2 exhibited consistent patterns across all species examined. The analysis of tissue gene expression profiles indicated that qGHRL was primarily expressed in the proventriculus and brain tissue, whereas qLEAP2 exhibited higher expression levels in the intestinal tissue, kidney, and liver tissue, differing slightly from previous studies conducted on chicken. It is necessary to investigate the significance of elevated expression of qGHRL in brain and qLEAP2 in kidney in the future. Further research has shown that the expression of qLEAP2 can quickly respond to changes in different energy states, whereas qGHRL does not exhibit the same capability. Overall, this study successfully cloned the complete cDNA sequences of qGHRL and qLEAP2, and conducted a comprehensive examination of their tissue expression profiles and gene expression levels in the main expressing organs across different energy states. Our current findings suggested that qLEAP2 is highly expressed in the liver, intestine, and kidney, and its expression level is regulated by feed intake.

Dietary restriction and life-history trade-offs: insights into mTOR pathway regulation and reproductive investment in Japanese quail.

Resources are needed for growth, reproduction and survival, and organisms must trade off limited resources among competing processes. Nutritional availability in organisms is sensed and monitored by nutrient-sensing pathways that can trigger physiological changes or alter gene expression. Previous studies have proposed that one such signalling pathway, the mechanistic target of rapamycin (mTOR), underpins a form of adaptive plasticity when individuals encounter constraints in their energy budget. Despite the fundamental importance of this process in evolutionary biology, how nutritional limitation is regulated through the expression of genes governing this pathway and its consequential effects on fitness remain understudied, particularly in birds. We used dietary restriction to simulate resource depletion and examined its effects on body mass, reproduction and gene expression in Japanese quails (Coturnix japonica). Quails were subjected to feeding at 20%, 30% and 40% restriction levels or ad libitum for 2 weeks. All restricted groups exhibited reduced body mass, whereas reductions in the number and mass of eggs were observed only under more severe restrictions. Additionally, dietary restriction led to decreased expression of mTOR and insulin-like growth factor 1 (IGF1), whereas the ribosomal protein S6 kinase 1 (RPS6K1) and autophagy-related genes (ATG9A and ATG5) were upregulated. The pattern in which mTOR responded to restriction was similar to that for body mass. Regardless of the treatment, proportionally higher reproductive investment was associated with individual variation in mTOR expression. These findings reveal the connection between dietary intake and the expression of mTOR and related genes in this pathway.

The relationship of MITF gene expression and promoter methylation with plumage colour in quail.

1. This study focused on the relationship between MITF mRNA expression and plumage colour in quail and the effect of promoter methylation on the expression of MITF mRNA.2. The CDS region of MITF mRNA was cloned by RT-PCR, followed by DNA sequencing. The RT-qPCR method was used to analyse the expression levels of MITF mRNA in dorsal skin tissue in Korean quail and Beijing white quail. The promoter region of the MITF gene was cloned, and the CpG island was predicted by the CpGplot program. The methylation levels of the CpG island were analysed using BS-PCR technology.3. Quail MITF mRNA contains a 1,476 bp complete ORF, which encodes a 492 amino acid residue protein. The MITF protein has no signal peptide or transmembrane region. The expression of MITF mRNA in dorsal tissue of Korean quail was significantly higher than that in Beijing white quail (p < 0.01). Abundant cis-elements and a 346 bp CpG island were found in the promoter region of the MITF gene. The average methylation level of the CpG island was 22 (22%) in Korean quail, and 46 (30%) in Beijing white quail (p < 0.05).4. The hypermethylation of the MITF gene promoter region in Beijing white quail resulted in a decrease in expression level, which was related to white feather colour.

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.

Embryonic methionine triggers post-natal developmental programming in Japanese quail.

Embryonic development is one of the most sensitive and critical stages when maternal effects may influence the offspring's phenotype. In birds and other oviparous species, embryonic development is confined to the eggs, therefore females must deposit resources into the eggs to prepare the offspring for the prevailing post-natal conditions. However, the mechanisms of such phenotypic adjustments remain poorly understood. We simulated a maternal nutritional transfer by injecting 1 mg of L-methionine solution into Japanese quail eggs before the onset of incubation. The increase in early methionine concentration in eggs activated the insulin/insulin-like signalling and mechanistic target of rapamycin (IIS/mTOR) signalling pathways and affected post-natal developmental trajectories. Chicks from methionine-supplemented eggs had higher expression of liver IGF1 and mTOR genes at hatching but were similar in size, and the phenotypic effects of increased growth became apparent only a week later and remained up to three weeks. Circulating levels of insulin-like growth factor-1 (IGF-1) and expression of ribosomal protein serine 6 kinase 1 (RPS6K1), the mTOR downstream effector, were elevated only three weeks after hatching. These results show that specific nutritional cues may have phenotypic programming effects by sequentially activating specific nutrient-sensing pathways and achieving transgenerational phenotypic plasticity.

Signaling pathways and regulatory networks in quail skeletal muscle development: insights from whole transcriptome sequencing.

Quail, as an advantageous avian model organism due to its compact size and short reproductive cycle, holds substantial potential for enhancing our understanding of skeletal muscle development. The quantity of skeletal muscle represents a vital economic trait in poultry production. Unraveling the molecular mechanisms governing quail skeletal muscle development is of paramount importance for optimizing meat and egg yield through selective breeding programs. However, a comprehensive characterization of the regulatory dynamics and molecular control underpinning quail skeletal muscle development remains elusive. In this study, through the application of HE staining on quail leg muscle sections, coupled with preceding fluorescence quantification PCR of markers indicative of skeletal muscle differentiation, we have delineated embryonic day 9 (E9) and embryonic day 14 (E14) as the start and ending points, respectively, of quail skeletal muscle differentiation. Then, we employed whole transcriptome sequencing to investigate the temporal expression profiles of leg muscles in quail embryos at the initiation of differentiation (E9) and upon completion of differentiation (E14). Our analysis revealed the expression patterns of 12,012 genes, 625 lncRNAs, 14,457 circRNAs, and 969 miRNAs in quail skeletal muscle samples. Differential expression analysis between the E14 and E9 groups uncovered 3,479 differentially expressed mRNAs, 124 lncRNAs, 292 circRNAs, and 154 miRNAs. Furthermore, enrichment analysis highlighted the heightened activity of signaling pathways related to skeletal muscle metabolism and intermuscular fat formation, such as the ECM-receptor interaction, focal adhesion, and PPAR signaling pathway during E14 skeletal muscle development. Conversely, the E9 stage exhibited a prevalence of pathways associated with myoblast proliferation, exemplified by cell cycle processes. Additionally, we constructed regulatory networks encompassing lncRNA‒mRNA, miRNA‒mRNA, lncRNA‒miRNA-mRNA, and circRNA-miRNA‒mRNA interactions, thus shedding light on their putative roles within quail skeletal muscle. Collectively, our findings illuminate the gene and non-coding RNA expression characteristics during quail skeletal muscle development, serving as a foundation for future investigations into the regulatory mechanisms governing non-coding RNA and quail skeletal muscle development in poultry production.

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.

Genome-wide association study for body weight and feed consumption traits in Japanese quail using Bayesian approaches.

The aim of this study was to perform a genome-wide association study (GWAS) based on Bayes A and Bayes B statistical methods to identify genomic loci and candidate genes associated with body weight gain, feed intake, and feed conversion ratio in Japanese quail. For this purpose, genomic data obtained from Illumina iSelect 4K quail SNP chip were utilized. After implementing various quality control steps, genotype data from a total of 875 birds for 2,015 SNP markers were used for subsequent analyses. The Bayesian analyses were performed using hibayes package in R (version 4.3.1) and Gibbs sampling algorithm. The results of the analyses showed that Bayes A accounted for 11.43, 11.65, and 11.39% of the phenotypic variance for body weight gain, feed intake, and feed conversion ratio, respectively, while the variance explained by Bayes B was 7.02, 8.61, and 6.48%, respectively. Therefore, in the current study, results obtained from Bayes A were used for further analyses. In order to perform the gene enrichment analysis and to identify the functional pathways and classes of genes that are over-represented in a large set of genes associated with each trait, all markers that accounted for more than 0.1% of the phenotypic variance for each trait were used. The results of this analysis revealed a total of 23, 38, and 14 SNP markers associated with body weight gain, feed intake, and feed conversion ratio in Japanese quail, respectively. The results of the gene enrichment analysis led to the identification of biological pathways (and candidate genes) related to lipid phosphorylation (TTC7A gene) and cell junction (FGFR4 and FLRT2 genes) associated with body weight gain, calcium signaling pathway (ADCY2 and CAMK1D genes) associated with feed intake, and glycerolipid metabolic process (LIPC gene), lipid metabolic process (ADGRF5 and ESR1 genes), and glutathione transferase (GSTK1 gene) associated with feed conversion ratio. Overall, the findings of this study can provide valuable insights into the genetic architecture of growth and feed consumption traits in Japanese quail.

Hepatic Transcriptomic Responses to Ethinylestradiol in Embryonic Japanese Quail and Double-Crested Cormorant.

Understanding species differences in sensitivity to toxicants is a critical issue in ecotoxicology. We recently established that double-crested cormorant (DCCO) embryos are more sensitive than Japanese quail (JQ) to the developmental effects of ethinylestradiol (EE2). We explored how this difference in sensitivity between species is reflected at a transcriptomic level. The EE2 was dissolved in dimethyl sulfoxide and injected into the air cell of eggs prior to incubation at nominal concentrations of 0, 3.33, and 33.3 µg/g egg weight. At midincubation (JQ 9 days; DCCO 16 days), livers were collected from five embryos/treatment group for RNA sequencing. Data were processed and analyzed using EcoOmicsAnalyst and ExpressAnalyst. The EE2 exposure dysregulated 238 and 1,987 genes in JQ and DCCO, respectively, with 78 genes in common between the two species. These included classic biomarkers of estrogen exposure such as vitellogenin and apovitellenin. We also report DCCO-specific dysregulation of Phase I/II enzyme-coding genes and species-specific transcriptional ontogeny of vitellogenin-2. Twelve Kyoto Encyclopedia of Genes and Genomes pathways and two EcoToxModules were dysregulated in common in both species including the peroxisome proliferator-activated receptor (PPAR) signaling pathway and fatty acid metabolism. Similar to previously reported differences at the organismal level, DCCO were more responsive to EE2 exposure than JQ at the gene expression level. Our description of differences in transcriptional responses to EE2 in early life stage birds may contribute to a better understanding of the molecular basis for species differences. Environ Toxicol Chem 2024;43:772-783. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.