Selective breeding for high and low antibody responses to inactivated Newcastle disease virus in Japanese quails

Uterus-specific transcriptional regulation underlies eggshell pigment production in Japanese quail

The precursor of heme, protoporphyrin IX (PPIX), accumulates abundantly in the uteri of birds, such as Japanese quail, Coturnix japonica, which has brown-speckled eggshells; however, the molecular basis of PPIX production in the uterus remains largely unknown. Here, we investigated the cause of low PPIX production in a classical Japanese quail mutant exhibiting white eggshells by comparing its gene expression in the uterus with that of the wild type using transcriptome analysis. We also performed genetic linkage analysis to identify the causative genomic region of the white eggshell phenotype. We found that 11 genes, including 5’-aminolevulinate synthase 1 (ALAS1) and hephaestin-like 1 (HEPHL1), were specifically upregulated in the wild-type uterus and downregulated in the mutant. We mapped the 172 kb candidate genomic region on chromosome 6, which contains several genes, including a part of the paired-like homeodomain 3 (PITX3), which encodes a transcription factor. ALAS1, HEPHL1, and PITX3 were expressed in the apical cells of the luminal epithelium and lamina propria cells of the uterine mucosa of the wild-type quail, while their expression levels were downregulated in the cells of the mutant quail. Biochemical analysis using uterine homogenates indicated that the restricted availability of 5’-aminolevulinic acid is the main cause of low PPIX production. These results suggest that uterus-specific transcriptional regulation of heme-biosynthesis-related genes is an evolutionarily acquired mechanism of eggshell pigment production in Japanese quail. Based on these findings, we discussed the molecular basis of PPIX production in the uteri of Japanese quails.

Nonsense mutation in PMEL is associated with yellowish plumage colour phenotype in Japanese quail

The L strain of Japanese quail exhibits a plumage phenotype that is light yellowish in colour. In this study, we identified a nonsense mutation in the premelanosome protein (PMEL) gene showing complete concordance with the yellowish plumage within a pedigree as well as across strains by genetic linkage analysis of an F₂ intercross population using approximately 2,000 single nucleotide polymorphisms (SNPs) that were detected by double digest restriction site-associated DNA sequencing (ddRAD-seq). The yellowish plumage was inherited in an autosomal recessive manner, and the causative mutation was located within an 810-kb genomic region of the LGE22C19W28_E50C23 linkage group (LGE22). This region contained the PMEL gene that is required for the normal melanosome morphogenesis and eumelanin deposition. A nonsense mutation that leads to a marked truncation of the deduced protein was found in PMEL of the mutant. The gene expression level of PMEL decreased substantially in the mutant. Genotypes at the site of the nonsense mutation were fully concordant with plumage colour phenotypes in 196 F₂ offspring. The nonsense mutation was not found in several quail strains with non-yellowish plumage. Thus, the yellowish plumage may be caused by the reduced eumelanin content in feathers because of the loss of PMEL function.

Strain differences in intermale aggression and possible factors regulating increased aggression in Japanese quail

The National Institute for Environmental Studies (NIES) of Japan established a strain of Japanese quail (Coturnix japonica) known as NIES-L by rotation breeding in a closed colony for over 35years; accordingly, the strain has highly inbred-like characteristics. Another strain called NIES-Brn has been maintained by randomized breeding in a closed colony to produce outbred-like characteristics. The current study aimed to characterize intermale aggressive behaviors in both strains and to identify possible factors regulating higher aggression in the hypothalamus, such as sex hormone and neuropeptide expression. Both strains displayed a common set of intermale aggressive behaviors that included pecking, grabbing, mounting, and cloacal contact behavior, although NIES-Brn quail showed significantly more grabbing, mounting, and cloacal contact behavior than did NIES-L quail. We examined sex hormone levels in the blood and diencephalon in both strains. Testosterone concentrations were significantly higher in the blood and diencephalon of NIES-Brn quail compared to NIES-L quail. We next examined gene expression in the hypothalamus of both strains using an Agilent gene expression microarray and real-time RT-PCR and found that gene expression of mesotocin (an oxytocin homologue) was significantly higher in the hypothalamus of NIES-Brn quail compared to NIES-L quail. Immunohistochemistry of the hypothalamus revealed that numbers of large cells (cell area>500μm²) expressing mesotocin were significantly higher in the NIES-Brn strain compared to the NIES-L strain. Taken together, our findings suggest that higher testosterone and mesotocin levels in the hypothalamus may be responsible for higher aggression in the NIES-Brn quail strain.

Genetic Divergence in Domestic Japanese Quail Inferred from Mitochondrial DNA D-Loop and Microsatellite Markers

To assess the genetic diversity of domestic Japanese quail (Coturnix japonica) populations, and their genetic relationships, we examined mitochondrial DNA (mtDNA) D-loop sequences and microsatellite markers for 19 Japanese quail populations. The populations included nine laboratory lines established in Japan (LWC, Quv, RWN, WE, AWE, AMRP, rb-TKP, NIES-L, and W), six meat-type quail lines reimported from Western countries (JD, JW, Estonia, NIES-Br, NIES-Fr, and NIES-Hn), one commercial population in Japan, and three wild quail populations collected from three Asian areas. The phylogenetic tree of mtDNA D-loop sequences revealed two distinct haplotype groups, Dloop-Group1 and Dloop-Group2. Dloop-Group1 included a dominant haplotype representing most of the quail populations, including wild quail. Dloop-Group2 was composed of minor haplotypes found in several laboratory lines, two meat-type lines, and a few individuals in commercial and wild quail populations. Taking the breeding histories of domestic populations into consideration, these results suggest that domestic quail populations may have derived from two sources, i.e., domestic populations established before and after World War II in Japan. A discriminant analysis of principal components and a Bayesian clustering analysis with microsatellite markers indicated that the domestic populations are clustered into four genetic groups. The two major groups were Microsat-Group1, which contained WE, and four WE-derived laboratory lines (LWC, Quv, RWN, and AWE), and Microsat-Group2 consisting of NIES-L, JD, JW, Estonia, NIES-Br, NIES-Fr, NIES-Hn, W, and commercial and wild populations. The remaining two lines (AMRP and rb-TKP) were each clustered into a separate clade. This hierarchical genetic difference between domestic quail populations is attributed to the genetic background derived from two different genetic sources-the pre-war and post-war populations-which is well supported by their breeding histories.

Avian Test Battery for the Evaluation of Developmental Abnormalities of Neuro- and Reproductive Systems

Most of the currently used toxicity assays for environmental chemicals use acute or chronic systemic or reproductive toxicity endpoints rather than neurobehavioral endpoints. In addition, the current standard approaches to assess reproductive toxicity are time-consuming. Therefore, with increasing numbers of chemicals being developed with potentially harmful neurobehavioral effects in higher vertebrates, including humans, more efficient means of assessing neuro- and reproductive toxicity are required. Here we discuss the use of a Galliformes-based avian test battery in which developmental toxicity is assessed by means of a combination of chemical exposure during early embryonic development using an embryo culture system followed by analyses after hatching of sociosexual behaviors such as aggression and mating and of visual memory via filial imprinting. This Galliformes-based avian test battery shows promise as a sophisticated means not only of assessing chemical toxicity in avian species but also of assessing the risks posed to higher vertebrates, including humans, which are markedly sensitive to nervous or neuroendocrine system dysfunction.

Different Photoperiodic Responses in Four Lines of Japanese Quail

Organisms measure day length to better adapt to seasonal changes in the environment; this phenomenon is called photoperiodism. The Japanese quail has a highly sophisticated photoperiodic mechanism and is an excellent model for the study of photoperiodism. Various lines of quail have been established during the domestication process. In the present study, we examined the effect of long day (LD) followed by short day (SD) on testicular weight in four lines of quail (L, AMRP, NIES-Br, and WE). When the quail were raised under SD conditions, testicular development was suppressed in all examined lines. The speed of the LD-induced testicular development of NIES-Br line was faster than that of AMRP line, while the speed of the SD-induced testicular regression of L line was significantly faster than that of WE line. These quail lines provide excellent model to uncover the underlying mechanism of seasonal testicular regression.

Effects of 3-methyl-4-nitrophenol on the reproductive toxicity in female Japanese quail (Coturnix japonica)

We previously showed that 3-methyl-4-nitrophenol (4-nitro-m-cresol, PNMC), a component of diesel exhaust particles and a degradation product of the insecticide fenitrothion, has reproductive toxicity in adult male and immature female Japanese quail (Coturnix japonica). Here we investigated effects of PNMC on the reproductive toxicity of mature female Japanese quail. The experiment consists of 3 periods of pretreatment, treatment, and post-treatment for 5 d each. The birds were reared, bred naturally for 1 week, and after 5 d of pretreatment, then injected intramuscularly with PNMC at doses 1, 10, or 100 mg/kg body weight daily for 5 d. Body weight, egg weight, and hatchability did not differ among the observation periods. However, at all doses of PNMC, the egg-laying rate showed a modest decrease during the treatment period, with recovery during the post-treatment period. Plasma concentrations of luteinizing hormone (LH) and estrodiol-17beta, were significantly decreased (p<0.05), and plasma concentrations of progesterone significantly increased (p<0.05) in birds treated with 10 and 100 mg/kg PNMC. These results suggest that PNMC have acute toxicity, and inhibited LH secretion, disturbing egg-laying in mature female quail. Our findings indicate that PNMC induces endocrine malfunction at the central level and subsequently disrupts reproductive processes in mature female quails.

The major histocompatibility complex (Mhc) class IIB region has greater genomic structural flexibility and diversity in the quail than the chicken

Background

The quail and chicken major histocompatibility complex (Mhc) genomic regions have a similar overall organization but differ markedly in that the quail has an expanded number of duplicated class I, class IIB, natural killer (NK)-receptor-like, lectin-like and BG genes. Therefore, the elucidation of genetic factors that contribute to the greater Mhc diversity in the quail would help to establish it as a model experimental animal in the investigation of avian Mhc associated diseases.

Aims and approaches

The main aim here was to characterize the genetic and genomic features of the transcribed major quail MhcIIB (CojaIIB) region that is located between the Tapasin and BRD2 genes, and to compare our findings to the available information for the chicken MhcIIB (BLB). We used four approaches in the study of the quail MhcIIB region, (1) haplotype analyses with polymorphic loci, (2) cloning and sequencing of the RT-PCR CojaIIB products from individuals with different haplotypes, (3) genomic sequencing of the CojaIIB region from the individuals with the different haplotypes, and (4) phylogenetic and duplication analysis to explain the variability of the region between the quail and the chicken.

Results

Our results show that the Tapasin-BRD2 segment of the quail Mhc is highly variable in length and in gene transcription intensity and content. Haplotypic sequences were found to vary in length between 4 to 11 kb. Tapasin-BRD2 segments contain one or two major transcribed CojaIIBs that were probably generated by segmental duplications involving c-type lectin-like genes and NK receptor-like genes, gene fusions between two CojaIIBs and transpositions between the major and minor CojaIIB segments. The relative evolutionary speed for generating the MhcIIBs genomic structures from the ancestral BLB2 was estimated to be two times faster in the quail than in the chicken after their separation from a common ancestor. Four types of genomic rearrangement elements (GRE), composed of simple tandem repeats (STR), were identified in the MhcIIB genomic segment located between the Tapasin-BRD2 genes. The GREs have many more STR numbers in the quail than in the chicken that displays strong linkage disequilibrium.

Conclusion

This study suggests that the Mhc classIIB region has a flexible genomic structure generated by rearrangement elements and rapid SNP accumulation probably as a consequence of the quail adapting to environmental conditions and pathogens during its migratory history after its divergence from the chicken.

MHC class IIB gene sequences and expression in quails (Coturnix japonica) selected for high and low antibody responses

Two quail lines, H and L, which were developed for high (H) and low (L) antibody production against inactivated Newcastle disease virus antigen, were used to examine differences in the organization, structure and expression of the quail Mhc class IIB genes. Four Coja class IIB genes in the H line and ten Coja class IIB genes in the L line were identified by gene amplification using standard and long-range PCRs and sequencing of the amplified products. RFLP analysis, sequencing and gene mapping revealed that the H line was fixed for a single class IIB haplotype, which we have designated CojaII-02HL- CojaII-01HL. In contrast, evidence was found for two class IIB haplotypes segregating in the L line. Some individuals were found to be homozygous for haplotype CojaII-08L- CojaII-07L and others were found to be heterozygous CojaII-08L- CojaII-07L/ CojaII-02HL- CojaII-01HL. However, expression of CojaII-02HL- CojaII-01HL was not detected in the L line. SRBC immunization induced a measurable antibody response in the serum and a line-specific class IIB gene expression in the peripheral white blood cells. CojaII-01HL was expressed at the highest level in the H line and CojaII-07L in the L line. The expression of the class IIB mRNA reached the highest level at approximately 1 week after the primary antibody response and then declined exponentially. The antibody and class IIB gene expression data obtained in response to SRBC immunization provide further evidence that quails within the L line had reduced immunocompetence compared with those in the H line.

Comparative Genomic Analysis of Two Avian (Quail and Chicken) MHC Regions

We mapped two different quail Mhc haplotypes and sequenced one of them (haplotype A) for comparative genomic analysis with a previously sequenced haplotype of the chicken Mhc. The quail haplotype A spans 180 kb of genomic sequence, encoding a total of 41 genes compared with only 19 genes within the 92-kb chicken Mhc. Except for two gene families (B30 and tRNA), both species have the same basic set of gene family members that were previously described in the chicken "minimal essential" Mhc. The two Mhc regions have a similar overall organization but differ markedly in that the quail has an expanded number of duplicated genes with 7 class I, 10 class IIB, 4 NK, 6 lectin, and 8 B-G genes. Comparisons between the quail and chicken Mhc class I and class II gene sequences by phylogenetic analysis showed that they were more closely related within species than between species, suggesting that the quail Mhc genes were duplicated after the separation of these two species from their common ancestor. The proteins encoded by the NK and class I genes are known to interact as ligands and receptors, but unlike in the quail and the chicken, the genes encoding these proteins in mammals are found on different chromosomes. The finding of NK-like genes in the quail Mhc strongly suggests an evolutionary connection between the NK C-type lectin-like superfamily and the Mhc, providing support for future studies on the NK, lectin, class I, and class II interaction in birds.

Immune response and resistance to infectious bursal disease virus of chicken lines selected for high or low antibody response to Escherichia coli

Two experimental broiler lines were developed by divergent selection for high (HH) and low (LL) antibody response to Escherichia coli. Antibody response of these lines to immunization with a commercial vaccine (whole inactivated virus, WIV) against infectious bursal disease virus (IBDV) or with proteins VP2 and VP3 of that virus, and their resistance to challenge with a virulent IBDV, were tested. The study was performed with 213 male and female chicks from the tenth generation of the HH and LL lines. At 15 d of age, after disappearance of maternal antibodies, chicks from each line were randomly divided into four groups and injected with WIV, VP2, VP3, or adjuvant alone as a negative control. Chicks were bled 18 d postinjection, and antibody titers were determined by ELISA. Ten days later, the chicks were challenged with a virulent strain of the virus and killed after 10 d; the ratio of bursa of Fabricius to 100 g BW was determined for each bird. Significant differences in antibody titers were found among immunized and control chicks. Chicks from the HH line exhibited significantly higher antibody titers than LL chicks in response to WIV and VP2 vaccines but not to VP3 vaccine. Following challenge, bursa weight (relative to BW) of HH and LL chicks vaccinated with WIV and VP2 was significantly higher (P < 0.01) than that of chicks vaccinated with VP3 or the challenged unvaccinated control. No difference was found in this parameter between the latter two groups. Possible explanations for the differences in the line response to VP2 and VP3 are discussed.

Antibody responses to sheep red blood cell and Brucella abortus antigens in a turkey line selected for increased body weight and its randombred control

Turkeys from a randombred control line (RBC2) and its subline (F) selected for increased 16-wk BW were tested for primary and secondary antibody responses to SRBC antigen and Brucella abortus antigen (BA). Previous studies have shown that the F line was more susceptible to Pasteurella multocida and Newcastle disease virus than was the RBC2 line. Individuals from the RBC2 and F lines were intravenously injected with 1 mL 5% SRBC antigen or 0.1 mL undiluted BA at 4 and 6 wk of age; blood samples were collected at 0, 4, 7, and 10 d post-immunization. Total, IgG, and IgM titers were measured by agglutination assays. Compared with the RBC2 line, the F line had generally higher total anti-SRBC titers; the differences were significant at 14 d postprimary immunization (PPI) (females); at 10 d postsecondary immunization (PSI) (males); and 4, 7, and 10 d PSI (females) (P < or = 0.05). The F line also had higher IgM titers at 14 d PPI (females) and at 10 d PSI (males) (P < or = 0.05). For IgG titers, a line difference was evident in females at 4 and 10 d PSI (P < or = 0.05); the F line had higher titers than did the RBC2 line. For the antibody response to BA in males, the F line had lower total and IgM titers at 10 d PPI (P < 0.05) than did the RBC2 line. No significant line differences in response to the BA were found in total and IgM titers in female turkeys or in IgG titers in both sexes at any time. These results suggest that selection for fast growth rate of turkeys might have resulted in changes in humoral immunity to the SRBC antigen and BA.

Sheep red blood cell and Brucella abortus antibody responses in chickens selected for multitrait immunocompetence

Chickens from replicated lines divergently selected for multitrait immunocompetence were tested for their antibody responses to sheep red blood cells and Brucella abortus antigen. All birds were injected with sheep red blood cells and B. abortus antigens at 4 and 9 wk of age, and blood samples were taken 6, 8, and 10 d postimmunization. Antibody titers were determined by using agglutination assays. For sheep red blood cell responses, the most marked difference was between the high and low lines postsecondary immunization. The high line titer was still rising at 10 d, whereas the low line had reached its peak at 8 d and was decreasing. This may be a result of the selection process in which the high line is selected for a high, persistent response to two T cell-dependent antigens at 3 wk postimmunization. For B. abortus responses, the only differences were between high and low lines postsecondary immunization. The high lines were always higher than the low lines, with differences getting smaller as time postimmunization increased. In summary, selection for multitrait immunocompetence resulted in changes in antibody response to unrelated antigens.

Parental effect on the humoral immune response to Escherichia coli and Newcastle disease virus in young broiler chicks

Genetic and environmental variables influence animal resistance to disease infection. In addition, maternal effects were also found in studies with egg-type chicken lines. In our laboratory, meat-type chicken lines were divergently selected for either early or late maturation of the immune system, based on family and individual antibody responsiveness at 10 d of age. The high-antibody (HC) and low-antibody (LC) lines differed significantly in the early immune response to Escherichia coli, to Newcastle disease virus (NDV) vaccination, and to several other immune functions. Reciprocal crosses between the HC and LC lines were performed over 2 yr at three different locations. Immune responses to E. coli and NDV vaccination provided separate estimates of maternal and paternal effects. Dam effect on immune response to E. coli vaccine was significantly larger than sire effect; the antibody titer in both reciprocal crosses was intermediate between the parental lines, but the mean titer of the HC x LC cross was significantly lower than that of the LC x HC cross. Similar, but not significant, ranking of crosses was observed for the response to NDV. Evidently, the level of the offspring humoral immune response was more a dam than a sire effect.

Genetic variation in the humoral immune response in Atlantic salmon (Salmo salar) against Aeromonas salmonicida A-layer

Antibody responses to Aeromonas salmonicida A-layer were analysed in family material of Atlantic salmon (Salmo salar), consisting of 791 fish belonging to 34 full-sib groups within 12 paternal half-sib groups. The fish were immunized twice and blood samples were collected three times. Significant increase in antibody titre from first to second, and from second to third sampling, was observed. Genetic variation in antibody titres was observed at the three samplings with estimated heritabilities ranging from 0.16 to 0.20, and a significant heritability estimate was recorded in the antibody response after the second immunization (h2 = 0.16). Moderate to high genetic (r = 0.5-0.72) and phenotypic (r = 0.29-0.57) correlations were found between the titre values at different samplings, and between selected titres and titre increases. Production parameters, such as mean slaughter weight and mean survival rate were obtained for fish which were reared commercially in the sea, and which belonged to the same full-sib groups as those analysed for A. salmonicida A-layer antibodies. No significant correlation between the mean antibody titre to A. salmonicida A-layer in this study and mean slaughter weight and survival rate in full-sib family material in the sea was observed.

Immunological parameters in meat-type chicken lines divergently selected by antibody response to Escherichia coli vaccination

Our group has established two lines of meat-type chickens divergently selected for early (HC line) and late (LC line) antibody responsiveness at 10 days of age to immunization with inactivated pathogenic Escherichia coli bacteria. The question addressed in the study presented here is whether this selection has changed other immunological responses, increasing the overall 'early' immunocompetence. Broilers of the third and fourth generations (S3 and S4) of the selected lines (HC and LC) and a control, unselected line (CT) were vaccinated at 10 days of age with E. coli vaccine, Newcastle virus vaccine (NDV), sheep erythrocytes (SRBC) or bovine serum albumin (BSA). Line-HC chicks exhibited higher antibody titers to E. coli, NDV and SRBC than CT or LC chicks. At 20 days of age HC chicks demonstrated a higher total protein and a higher beta- and gamma-globulin levels in their serum. At 21 days of age, HC chicks cleared carbon particles faster than LC chicks. Peripheral blood lymphocytes (PBL) from HC chicks vaccinated with E. coli vaccine, proliferated in vitro more actively in the presence of the stimulating antigen than the PBL of LC chicks. Peripheral blood lymphocytes (PBL) obtained from HC-line chicks exhibited a higher proliferative response to concanavalin A (Con A)-, phytohemagglutinin (PHA)- or pokeweed mitogen (PWM)-stimulation than LC PBL. These results demonstrate that the selection for high or low antibody response to E. coli at a young age resulted also in a significant change in the response of other parameters of the immune system. The high response to E. coli was found to be associated with a high antibody response to other antigens (NDV and SRBC), increased phagocytic activity and increased proliferative response to antigen or mitogens. The selection most probably affected early immunocompetence.

Replicated divergent selection of broiler chickens for high or low early antibody response to Escherichia coli vaccination

Four sublines of broiler chickens were selected from a base population for three generations for high or low antibody response to vaccination with Escherichia coli at 10 days of age. Two sublines were selected for a high response (HC) and two for a low response (LC). Realized heritability estimates over three generations of selection for each pair of replicated lines averaged .23 in HC lines and .32 in LC lines. No correlated response in the important production trait, body weight at marketing age, was observed. The ability to survive pathogenic E. coli challenge with or without prevaccination showed no differences between the lines in the unvaccinated chicks, although following vaccination there was higher mortality and morbidity in the LC lines. These data suggest that the use of antibody response in young chicks to E. coli vaccine may be a useful genetic indication of more general disease resistance.

Selection for early responsiveness of chicks to Escherichia coli and Newcastle disease virus

A broiler chicken population was divergently selected for high or low early immune responses to Escherichia coli and to Newcastle disease virus (NDV) vaccines. Four selection cycles were performed in one replicate, and a single cycle in a second replicate. Selection was based on sire-family averages of a titer index (TI) calculated as the mean titer of antibodies produced by offspring vaccinated with either E. coli or NDV at 18 or 10 days of age, respectively. After the first selection cycle, TI of the early-high (EH) line were 22 and 38% greater than those of the early-low (EL) line in Replicates A and B, respectively. After four selection cycles, the average immune response to E. coli and NDV of Line EH exceeded that of Line EL by 68%. Viability was greater in the EH than in the EL line. Realized family heritabilities were .72 and .67 in Replicates A and B, respectively and the levels of response to the two antigens were not genetically correlated. The immune response of the EH line developed earlier than that in the EL line as shown by fewer nonresponders against E. coli and the higher response of this line against the two antigens at young ages. Mortality after challenge at 18 days of age and general mortality from hatching to 20 wk of age was lower in Line EH than in Line EL. Body weights at 7 wk were higher in EH than EL chicks.

Immunological traits in generations 7 to 12 of two lines of Japanese quail selected for high or low antibody response to Newcastle disease virus

Several immunological traits were compared in lines of Japanese quail selected for high and low secondary immune responses to anti-Newcastle disease virus (NDV). The high line of quail, selected for high ability to produce antibodies, was more responsive in both their primary response to NDV antigen used in the selection as well as to other antigens used in selection process including NDV (Ishi strain), tissue culture-derived Newcastle disease (TCND strain), NDV strain B1, influenza virus, sheep erythrocytes, and Salmonella pullorum than the low line, selected for low ability to produce antibody titers. Mitogenic response to phytohemagglutinin mitogen in the blood lymphocytes from high line quail was more reactive than those from low line quail. Significant line differences were also found in the number of spontaneous rosette cells produced by blood lymphocytes with both fowl and rabbit erythrocytes; the number in the high line exceeded those in the low line.