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.

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.

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.

In ovo o,p'-DDT exposure induces malformation of reproductive organs and alters the expression of genes controlling sexual differentiation in Japanese quail embryo.

In ovo exposure to o,p'-dichloro-diphenyl-trichloroethane (o,p'-DDT) impairs reproduction by inducing malformation of the reproductive organs in birds, although the mechanism remains unclear. Here, we examined the effects of o,p'-DDT on the development of the reproductive organs, the expression of genes controlling sexual differentiation, and the plasma concentrations of testosterone and estradiol in Japanese quail embryos. o,p'-DDT-containing sesame oil was injected into the yolk sac on Embryonic Day (E) 3 at a dose of 500, 2,000, or 8,000 µg per egg. On E15, the reproductive organs were observed; the gonads and Müllerian ducts (MDs) were sampled to measure the mRNA of steroidogenic enzymes, sex steroid receptors, anti-Müllerian hormone (AMH), and AMH receptor 2 (AMHR2); blood samples were collected to assay plasma testosterone and estradiol levels; and the gonads were used for histological analysis. o,p'-DDT dose-dependently increased the prevalence of hypertrophic MDs in females and residual MDs in males. In female MDs, o,p'-DDT dose-dependently decreased estrogen receptor (ER) α, ERß, and AMHR2 mRNA expression. o,p'-DDT dose-dependently induced left-biased asymmetry of testis size, and ovary-like tissue was found in the left testis after exposure to 8,000 µg per egg o,p'-DDT, although asymmetric gene expression did not occur. o,p'-DDT did not affect ovarian tissue but did decrease 17α-hydroxylase/C17-20 lyase mRNA expression and dose-dependently increased ERß mRNA expression. o,p'-DDT decreased plasma testosterone concentrations in females. These findings suggest that o,p'-DDT induces hypertrophy of the MDs and ovarian tissue formation in the left testis. Abnormal MD development may be linked to altered gene expression for sensing estrogens and AMH signals.

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.

Association analysis of production traits of Japanese quail (Coturnix japonica) using restriction-site associated DNA sequencing.

This study was designed to perform an association analysis and identify SNP markers associated with production traits of Japanese quail using restriction-site-associated DNA sequencing. Weekly body weight data from 805 quail were collected from hatching to 16 weeks of age. A total number of 3990 eggs obtained from 399 female quail were used to assess egg quality traits. Egg-related traits were measured at the beginning of egg production (first stage) and at 12 weeks of age (second stage). Five eggs were analyzed at each stage. Traits, such as egg weight, egg length and short axes, eggshell strength and weight, egg equator thickness, yolk weight, diameter, and colour, albumen weight, age of first egg, total number of laid eggs, and egg production rate, were assessed. A total of 383 SNPs and 1151 associations as well as 734 SNPs and 1442 associations were identified in relation to quail production traits using general linear model (GLM) and mixed linear model (MLM) approaches, respectively. The GLM-identified SNPs were located on chromosomes 1-13, 15, 17-20, 24, 26-28, and Z, underlying phenotypic traits, except for egg and albumen weight at the first stage and yolk yellowness at the second stage. The MLM-identified SNPs were positioned on defined chromosomes associated with phenotypic traits except for the egg long axis at the second stage of egg production. Finally, 35 speculated genes were identified as candidate genes for the targeted traits based on their nearest positions. Our findings provide a deeper understanding and allow a more precise genetic improvement of production traits of Galliformes, particularly in Japanese quail.

Rapid decline of prenatal maternal effects with age is independent of postnatal environment in a precocial bird.

Maternal effects are an important source of phenotypic variation with potentially large fitness consequences, but how their importance varies with the quality of the environment across an individual's ontogeny is poorly understood. We bred Japanese quail (Coturnix japonica) of known pedigree and experimentally manipulated the quality of the offspring diet, to estimate the importance of prenatal maternal effects in shaping variation in body mass from hatching to adulthood. Maternal genetic effects on body mass at hatching were strong, and largely caused by variation in egg mass, but their importance rapidly declined with age. Whereas there was a large effect of diet on growth, this did not affect the decline of maternal effects variance. The importance of additive genetic and residual variance increased with age, with the latter being considerably larger in the poor diet treatment. Hence, we found no evidence for prenatal maternal effect by postnatal environment interactions and that prenatal maternal effects are rapidly replaced by direct additive genetic and residual effects when offspring start to develop outside the egg. Thereby these results shed new light on the dynamics of the role of maternal versus offspring genes across ontogeny and environments.

Coronary artery established through amniote evolution.

Coronary arteries are a critical part of the vascular system and provide nourishment to the heart. In humans, even minor defects in coronary arteries can be lethal, emphasizing their importance for survival. However, some teleosts survive without coronary arteries, suggesting that there may have been some evolutionary changes in the morphology and function of coronary arteries in the tetrapod lineage. Here, we propose that the true ventricular coronary arteries were newly established during amniote evolution through remodeling of the ancestral coronary vasculature. In mouse (Mus musculus) and Japanese quail (Coturnix japonica) embryos, the coronary arteries unique to amniotes are established by the reconstitution of transient vascular plexuses: aortic subepicardial vessels (ASVs) in the outflow tract and the primitive coronary plexus on the ventricle. In contrast, amphibians (Hyla japonica, Lithobates catesbeianus, Xenopus laevis, and Cynops pyrrhogaster) retain the ASV-like vasculature as truncal coronary arteries throughout their lives and have no primitive coronary plexus. The anatomy and development of zebrafish (Danio rerio) and chondrichthyans suggest that their hypobranchial arteries are ASV-like structures serving as the root of the coronary vasculature throughout their lives. Thus, the ventricular coronary artery of adult amniotes is a novel structure that has acquired a new remodeling process, while the ASVs, which occur transiently during embryonic development, are remnants of the ancestral coronary vessels. This evolutionary change may be related to the modification of branchial arteries, indicating considerable morphological changes underlying the physiological transition during amniote evolution.

Coronary arteries are tasked with supplying the heart with oxygenated blood and nutrients. Any blockage or developmental problem in these blood vessels can have severe and sometimes lethal consequences. Due to their importance for health, researchers have extensively studied how coronary arteries form in humans and mice; a more limited range of studies have also looked at their equivalent in zebrafish. However, little is known about these structures develop in animals such as birds, amphibians, or other groups of fish. This makes it difficult to retrace the evolutionary processes that have given rise to the coronary arteries we are familiar with in mammals. To address this knowledge gap, Mizukami et al. set out to compare blood vessel development around the heart of mammals, birds, amphibians, and fish. To do this, they performed detailed anatomical studies of blood vessel structure at different stages of development in mice as well as quail, frogs and newts, zebrafish and sharks. In both mice and quail, small arterial subepicardial vessels (or ASVs) emerged early in development around the heart; these subsequently reorganised and remodelled themselves to give rise to the 'true' coronary arteries characteristic of the mature heart. Frogs and newts also developed similar ASV-like structures; however, unlike their mammalian and bird equivalents, these vessels did not reorganise, instead being retained into adulthood. In fish, blood vessel development resembled that of amphibians, suggesting that the coronary artery-like structures seen in some fish are an 'ancestral' form of ASVs, rather than the equivalent of the mature coronary arteries in mammals and birds. This work sheds light on the evolutionary processes shaping essential structures in the heart. In the future, Mizukami et al. hope that this knowledge will help develop a greater range of experimental animal models for studying heart disease and potential treatments.

Association analysis of PMEL gene expression and single nucleotide polymorphism with plumage color in quail.

To explore the relationship between PMEL gene and quail plumage color, to provide a reference for subsequent quail plumage color breeding. In this experiment, RT-qPCR technology was used to analyze the relative mRNA expression levels of Korean quail (maroon) and Beijing white quail embryos at different developmental stages. Two SNPs in PMEL gene were screened based on the RNA-Seq data of skin tissues of Korean quail and Beijing white quail during embryonic stage. The KASP technology was used for genotyping in the resource population and correlation analysis was carried out with the plumage color traits of quail. Finally, the bioinformatics technology was used to predict the effects of these two SNPs on the structure and function of the encoded protein. The results showed that the expression levels of PMEL gene during the embryonic development of Beijing white quail were extremely significantly higher than that of Korean quail (p < 0.01). The frequency distribution of the three genotypes (AA, AB, and BB) of the Beijing white quail at the c. 1030C > T and c. 1374A > G mutation sites were extremely significantly different from that of the Korean quail (p < 0.01). And there was a significant correlation between the c. 1374A > G mutation site with white plumage phenotype. Bioinformatics analysis showed that SNP1 (c. c1030t) located in exon 6 was a harmful mutation site, and SNP2 (c. a1374g) located in exon 7 was a neutral mutation site. Protein conservation prediction showed that the coding protein P344S site caused by SNP1 (c. c1030t) site and the coding protein I458M site caused by SNP2 (c. g2129a) site were non-conservative sites. The results of this experiment showed that the PMEL gene was associated with the plumage color traits of quail and could be used as a candidate gene for studying the plumage color of quail.

Increased male-induced harm in response to female-limited selection: interactive effects between intra- and interlocus sexual conflict?

Interlocus sexual conflict (IRSC) occurs because of shared interactions that have opposite effects on male and female fitness. Typically, it is assumed that loci involved in IRSC have sex-limited expression and are thus not directly affected by selective pressures acting on the other sex. However, if loci involved in IRSC have pleiotropic effects in the other sex, intersexual selection can shape the evolutionary dynamics of conflict escalation and resolution, as well as the evolution of reproductive traits linked to IRSC loci, and vice versa. Here we used an artificial selection approach in Japanese quail (Coturnix japonica) to test if female-limited selection on reproductive investment affects the amount of harm caused by males during mating. We found that males originating from lines selected for high female reproductive investment caused more oxidative damage in the female reproductive tract than males originating from lines selected for low female reproductive investment. This male-induced damage was specific to the oviduct and not found in other female tissues, suggesting that it was ejaculate-mediated. Our results suggest that intersexual selection shapes the evolution of IRSC and that male-induced harm may contribute to the maintenance of variation in female reproductive investment.

The effects of myostatin mutation on the tibia bone quality in female Japanese quail before and after sexual maturation.

In the modern layer industry, improvement of bone quality is one of the prior tasks to solve from economic and welfare standpoints. In addition to nutritional and environmental factors, genetic factors have been considered major factors regulating bone quality in layers but are yet to be fully investigated due to limitations on available animal models. Initially, the myostatin (MSTN) gene was genetically edited in quail to investigate the effect of MSTN mutation on economic traits in meat producing poultry species. In the current study, the function of the MSTN gene on regulation of bone quality in layers was investigated using MSTN mutant female quail as an animal model. Tibia bones were collected from wild-type (WT) and MSTN mutant female quail at 5 wk old and 4 mo old, representing prelaying and actively laying stages, respectively. Left tibia bones were analyzed by microcomputed tomography scanning to evaluate the architectural characteristics, while bone breaking strength (BBS) was measured using right tibia bones. At 5 wk of age, MSTN mutant female quail showed higher BBS and values on parameters related to bone quality such as bone mineral contents (BMC), bone mineral density (BMD), bone volume (BV), and/or trabecular bone thickness in whole diaphysis, whole metaphysis, and metaphyseal trabecular bone, compared to WT female quail. Although BBS and BMD became similar between the 2 groups at 4 mo of age, higher TV and TS in whole metaphysis and higher BMC and TV in whole diaphysis of MSTN mutant group compared to those of WT group suggested that the improved tibia bone quality by MSTN mutation before sexual maturation lasted to a certain degree even after sexual maturation. The use of the MSTN mutant female model provided new insights into genetic regulation on female quail bone quality depending on physiological changes.

Assessment of variations in productive performance of two different plumage color varieties of Japanese quail and their reciprocal crosses.

This study aimed to detect the phenotypic differences between the brown (BB) and white (WW) feathered quails and their reciprocal crosses (BW and WB) over two successive generations. The WW and cross quails, especially the BW, had the heaviest body weights, throughout the studied period, with significant variations between the two studied generations (P<0.05). Moreover, the WW and BW possessed the largest egg production during the F1, while in the F2, the BB had superiority among the studied quails with a prominent superiority of the F2 over the F1 (P<0.05). However, the F1 had higher egg weights than F2 with superiority of WW quails compared to the others (P<0.05). Also, the WW quails had the lowest lipid contents of the eggs. These phenotypic variations among the studied quails might be preliminarily explained by the results of the analyzed microsatellite markers despite the few markers used. The high variability among the BW and WB quails might be due to the larger number of alleles (NA and Ne) and the lower values of FIS with low heterozygosity levels (HO and He). Moreover, the BW and BB were the closest, while WB and WW were the farthest because of the high and low genetic identities and the high and low genetic distance between them, respectively. So the obtained results might introduce an initial scientific basis for evaluating and employing the genetic properties of BB, WW, BW, and WB quails in further genetic improvement program, and more microsatellite markers are recommended.

Development and Initial Testing of EcoToxChip, a Novel Toxicogenomics Tool for Environmental Management and Chemical Risk Assessment.

New approach methods (NAMs) are increasingly important to help accelerate the pace of ecological risk assessment and offer more ethical, affordable, and efficient alternatives to traditional toxicity tests. In the present study, we describe the development, technical characterization, and initial testing of a toxicogenomics tool, EcoToxChip (384-well quantitative polymerase chain reaction [qPCR] array), to support chemical management and environmental monitoring for three laboratory model species-fathead minnow (Pimephales promelas), African clawed frog (Xenopus laevis), and Japanese quail (Coturnix japonica). Chip design, including gene selection, was informed by a diverse end-user group and quality control metrics (e.g., primer assay, reverse transcription, and PCR efficiency) performed well based on a priori established criteria. Correlation with RNA sequencing (seq) data provided additional confidence in this novel toxicogenomics tool. Although the present study represents an initial testing of only 24 EcoToxChips for each of the model species, the results provide increased confidence in the robustness/reproducibility of EcoToxChips for evaluating perturbations in gene expression associated with chemical exposure and thus, this NAM, combined with early-life stage toxicity testing, could augment current efforts for chemical prioritization and environmental management. Environ Toxicol Chem 2023;42:1763-1771. © 2023 SETAC.

A custom-made AAV1 variant (AAV1-T593K) enables efficient transduction of Japanese quail neurons in vitro and in vivo.

The widespread use of rodents in neuroscience has prompted the development of optimized viral variants for transduction of brain cells, in vivo. However, many of the viruses developed are less efficient in other model organisms, with birds being among the most resistant to transduction by current viral tools. Resultantly, the use of genetically-encoded tools and methods in avian species is markedly lower than in rodents; likely holding the field back. We sought to bridge this gap by developing custom viruses towards the transduction of brain cells of the Japanese quail. We first develop a protocol for culturing primary neurons and glia from quail embryos, followed by characterization of cultures via immunostaining, single cell mRNA sequencing, patch clamp electrophysiology and calcium imaging. We then leveraged the cultures for the rapid screening of various viruses, only to find that all yielded poor to no infection of cells in vitro. However, few infected neurons were obtained by AAV1 and AAV2. Scrutiny of the sequence of the AAV receptor found in quails led us to rationally design a custom-made AAV variant (AAV1-T593K; AAV1*) that exhibits improved transduction efficiencies in vitro and in vivo (14- and five-fold, respectively). Together, we present unique culturing method, transcriptomic profiles of quail's brain cells and a custom-tailored AAV1 for transduction of quail neurons in vitro and in vivo.

Research Note: Polymorphisms of gonadotrophin-releasing hormone gene and their association with growth traits in quail (Coturnix Coturnix).

This study aimed to identify polymorphisms of gonadotropin-releasing hormone (GnRH) gene and their association with growth traits in quail by PCR and direct sequencing. Genomic DNA was extracted from quail blood samples of 36 from Savimalt (SV) and 49 from French Giant (FG). Growth traits were measured and used for candidate gene analysis, as body weight (BW), shank length (SL), chest width (CW), chest depth (CD), breastbone length (BBL), body length (BL), and shank circumference (SC). The results showed that a total of 20 SNPs were detected in GnRH gene, whereas 8 SNPs were significantly associated with growth traits (P < 0.05). The T215C, G279A, C458T, A520G, and C547G were significantly associated with SL at 3 wk of age in the FG strain, whereas A583T was significantly related to BBL and BL, and C591T was significantly related to SL, BBL, and BL, whereas A592G was significantly correlated with SL, CW, CD, BBL, and BL (P < 0.05). The 8 SNPs were significantly related to CW, CD, and BBL at 3 wk of age in the SV strain, whereas A583T, C591T, and A592G were significantly associated with BW (P < 0.05). The G279A showed significant correlations with SL at 5 wk of age in FG, whereas A583T showed significant associations with SC in FG, and C591T was significantly associated with BW and SC in FG, whereas A592T was significantly related to BW, SL, and CD in FG (P < 0.05). The T215C, G279A, C458T, A520G, and C547G were significantly correlated with BW, CW, BBL, and BL at 5 wk of age in SV, whereas A583T, C591T, and A592G were significantly related to BW, SL, CW, BBL, and BL (P < 0.05). Haplotypes based on 8 SNPs showed significant correlation with BW, SL, CW, CD, BBL, BL, and SC in FG (P < 0.05). In conclusion, the GnRH gene could be used as a molecular genetic marker to provide theoretical foundation to improve growth traits in quail.

Genetic evaluation for survival traits in Japanese quail line selected for fast growth rate.

The main objectives of this study were to estimate genetic parameters for the survival, longevity and evaluate risk factors for the occurrence of mortality in a Japanese quail line selected for high growth rate during the period from hatch to 21 days of age (GR1-21) for eight generations and its control. Total number of 1095, 2289 and 16,506 for sires, dams and progeny, respectively, was used to estimate genetic parameters, a separate hatch of 687 chicks was used to examine the risk factors of quails in the selected (SL, 438) and control (CL, 249) lines. The proportion of censored quails until 42 days of age was 82.20 and 87.14 for SL and CL, respectively. The CL showed higher longevity than SL (38.42 vs. 36.86 days). In the two tested lines, mortality% significantly declined when body weight at death increased, however, the CL had a higher reduction of mortality% than the SL (50 vs. 42%). Survival and longevity had low heritability values, low genetic and phenotypic correlations between survival and longevity with GR1-21 and ranging from 0.025 to 0.208. The survival tended to be less correlated with GR1-21 and body weight at marketing age than the longevity.

Toxin genotypes of Clostridium perfringens isolates from common quail (Coturnix coturnix) with or without acute necrotic enteritis.

Clostridial diseases are one of the foremost causes of mortality in quails which occur by Clostridium colinum, Clostridium perfringens (C. perfringens), and Clostridium sordellii. C. perfringens genotypes responsible for quail enteritis are not well understood. In this study, the prevalence of C. perfringens genotypes was investigated in common quail (Coturnix coturnix) farms that suffered from acute necrotic enteritis (diarrhoeic) and compared with healthy (non-diarrhoeic) quails. Toward this end, C. perfringens isolates were collected and genotyped for 16s rRNA, cpa, cpb, cpb2, etx, iap, cpe, netB, and tpeL genes, using PCR. It was revealed that 42, 23, and 19 isolates belonged to toxinotypes A, F, and G, respectively, and the other toxinotypes were not obtained. The recovery ratio of C. perfringens from diarrhoeic farms roughly doubled in non-diarrhoeic farms (40.0% versus 21.5%, p = 0.03). Also, we observed a high isolation ratio of the cpb2 genotype (90.48%), which was significantly eminent in the diarrhoeic group (94.2%, p < 0.05). Although the prevalence of tpeL genes was low (15.48%), there was an interesting relationship between this gene and cpb2, so we did not obtain cpb2-tpeL-. This study showed the prevalence of types A, F, and G of C. perfringens in quail enteritis. Also, we reported tpeL+C. perfringens strains in quail for the first time and its frequent co-occurrence with the cpb2 gene. These results highlight the necessity of more accurate investigations of the C. perfringens genotype in different hosts to verify the exact role of these toxins in quail enteritis.

Effects of thiacloprid exposure on microbiota-gut-liver axis: Multiomics mechanistic analysis in Japanese quails.

Neonicotinoid insecticides (NNIs) are the most widely used class of pesticides globally. However, NNIs may cause adverse health effects, including chronic liver disease, and perturbation of the gut microbiota. Thiacloprid (THI) is one of the NNIs widely used in agriculture. Therefore, it is essential to elucidate effects of THI on the microbiota-gut-liver axis to assess the risk of chronic liver disease following exposure to NNIs. This study aimed at investigating whether THI exposure promoted liver injury by altering the gut microbiota and related metabolites. In this study, healthy male quails were exposed to 2 or 4 mg/kg THI or 0.75 % (w/v) saline once daily for 6 weeks, respectively. Metabolomics, 16S rRNA sequencing, and transcriptomic methods were performed to analyze the toxic mechanisms of THI in Japanese quails. We found that THI evoked damage and disruption to intestinal barrier function, leading to increased harmful substances such as lipopolysaccharide (LPS) and phenylacetic acid entering the liver. Besides, our results showed significantly altered hepatic bile acid and cholesterol metabolism in THI-exposed quails, with abnormal liver lipid metabolism, showing severe liver injury, fibrosis, and steatosis compared with the control quails. In conclusion, THI exposure aggravates liver injury via microbiota-gut-liver axis.