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

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.