Proliferative effects of bovine and porcine thyroglobulins on thyroid epithelial cells

An Evolutionary Genomic Perspective on the Breeding of Dwarf Chickens

The evolutionary history for dwarfism in chickens remains an enigma. Herein, we explore the evolution of the Serama, the smallest breed of chicken. Leveraging comparative population genomics, analyses identify several genes that are potentially associated with the growth and development of bones and muscles. These genes, and in particular both POU1F1 and IGF1, are under strong positive selection. Three allopatric dwarf bantams (Serama, Yuanbao, and Daweishan) with different breeding-histories, form distinct clusters and exhibit unique population structures. Parallel genetic mechanisms underlay their variation in body size. These findings provide insights into the multiple and complex pathways, depending on genomic variation, that chicken can take in response to aviculture selection for dwarfism.

Phylogenetic analysis of the human thyroglobulin regions

Thyroglobulin is a large protein present in all vertebrates. It is synthesized in the thyrocytes and exported to lumen of the thyroid follicle, where its tyrosine residues are iodinated . The iodinated thyroglobulin is reintegrated into the cell and processed (cleaved to free its two extremities) for thyroid hormone synthesis. Thyroglobulin sequence analysis has identified four regions of the molecule: Tg1, Tg2, Tg3 and ChEL. Structural abnormalities and mutations result in different pathological consequences, depending on the thyroglobulin region affected. We carried out a bioinformatic analysis of thyroglobulin, determining the origin and the function of each region. Our results suggest that the Tg1 region acts as a binding protein on the apical membrane, the Tg2 region is involved in protein adhesion and the Tg3 region is involved in determining the three-dimensional structure of the protein. The ChEL domain is involved in thyroglobulin transport, dimerization and adhesion. The presence of repetitive domains in the Tg1, Tg2 and Tg3 regions suggests that these domains may have arisen through duplication.