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.

Numerous proteins cannot be sufficiently prepared by ordinary recombinant DNA techniques because they are unstable or have deleterious effects on the host cell. One idea to prepare such proteins is to produce them as protein inclusions. Here we developed a novel system to effectively prepare proteins by using peptide tags derived from the insecticidal Cry toxin of a soil bacterium, Bacillus thuringiensis. Fusion with this peptide tag, designated 4AaCter, facilitates the formation of protein inclusions of glutathione S‐transferase in Escherichia coli without losing the enzyme activity. Application of 4AaCter to the production of syphilis antigens TpN15, TpN17 and TpN47 from Treponema pallidum yielded excellent results, including a dramatic increase in the production level, simplification of the product purification and high reactivity with syphilis antibody. The use of 4AaCter may provide an innovational strategy for the efficient production of proteins.

We have identified three members of the heat shock protein (HSP) 70 family from the Japanese quail, Coturnix japonica. The coding regions of the genes, CjHSPA2, CjHSPA5 and CjHSPA8, exhibit more than 96% similarity to related genes in the chicken, GgHSP70, GgHSPA5 and GgHSC70. The putative proteins encoded by the quail genes contain motifs considered essential for HSP70 family members. In addition, the predicted proteins are more similar to HSPA2, HSPA5, and HSPA8 proteins from vertebrates than they are to other members of the HSP70 family. As is true for orthologs from chicken and mammals, the quail genomic loci consist of a single exon (CjHSPA2) or eight exons (CjHSPA5 and CjHSPA8). The promoter regions of the genes also contain conserved motifs and are similar in structure to promoter regions of related genes in other species. Furthermore, gene order in the regions surrounding the quail HSP70 has been preserved, providing evidence that the genomic regions are orthologous to HSP70-containing regions in the chicken genome. One of the quail HSP70-related genes, CjHSPA2, exhibited a robust response to heat shock treatment and transcription of CjHSPA8 mRNA was weakly induced by heat treatment. Taken together, the data suggest that CjHSPA2, CjHSPA5 and CjHSPA8 encode orthologs of HSPA2, HSPA5 and HSPA8 with the notable difference that CjHSPA2 and CjHSPA8 are heat shock-inducible genes, whereas HSPA2 and HSPA8 are constitutively expressed in a heat shock-independent manner.

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In order to identify the complete cDNA sequences of three members of the heat shock protein (HSP) 70 family -NmHSPA2, NmHSPA5 and NmHSPA8 -from guinea fowl (Numida meleagris), the mRNA of white blood cells were analyzed using reverse transcriptase-polymerase chain reaction and the rapid amplification of cDNA ends method. The nucleotide sequences for these three cDNA exhibited more than 96% similarity to chicken HSP70 (GgHSP70), chicken glucoseregulated protein 78 (GgGRP78) and chicken heat-shock cognate protein 70 (GgHSC70). The translated amino acid sequences of these guinea fowl HSP70 family homologs contained essential motifs for the HSP70 family, and showed a higher sequence identity to the HSPA2, HSPA5 and HSPA8 orthologs from several vertebrates than other members of the HSP70 family. The NmHSPA2, NmHSPA5 and NmHSPA8 contained the HSPA2 specific insertion, the HSPA5 specific motif (endoplasmic reticulum-targets) and the HSPA8 specific insertion, respectively. As mentioned above, we concluded that NmHSPA2, NmHSPA5 and NmHSPA8 were orthologs of HSPA2, HSPA5 and HSPA8, respectively.