Collagen gene expression during chondrogenesis from chick periosteum-derived cells

AbstractChick periosteum-derived cells, which do not enter the chondrogenic cell lineage during normal bone development and growth, exhibit chondrogenic potential in high cell density culture conditions. In such cultures, collagen gene expression was temporally analyzed at the mRNA level by a reverse transcription PCR (RT-PCR) procedure, which showed that α1(II) and α1(IX) collagen mRNAs are coordinately increased, coincident with the onset of overt chondrogenesis, and subsequently decreased as chondrocytes exhibited hypertrophic characteristics. α1(X) collagen mRNA was detected well before the onset of chondrogenesis and markedly increased along with the hypertrophic change. For α2(I) collagen, both the bone/tendon form and the cartilage form of mRNA were detected throughout the culture period. This culture system provides an experimental vehicle capable of investigating the molecular events involved in the full range of chondrogenic differentiation starting from uncommitted periosteum-derived mesenchymal stem cells

Selfish genes and sexual selection: the impact of genomic parasites on host reproduction

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Selfish genetic elements (SGEs) such as replicating mobile elements, segregation distorters, and maternally inherited endosymbionts, bias their transmission success relative to the rest of the genome to increase in representation in subsequent generations. As such they generate conflict with the rest of the genome. Such intra-genomic conflict is also a hallmark of sexually antagonistic (SA) alleles, which are shared genes between the sexes but that have opposing fitness effects when expressed in males and females. However, while both SGEs and SA alleles are recognised as common and potent sources of genomic conflict, the realisation that SGEs can also generate sexually antagonistic selection and contribute to sexual conflict in addition to generate sexual selection is largely overlooked. Here I show that SGEs frequently generate sex-specific selection and outline how SGEs that are associated with compromised male fertility can shape female mating patterns, play a key role in the dynamics of sex determination systems, and likely be an important source of sexually antagonistic genetic variation. Given the prevalence of SGEs their contribution to sexual conflict is likely to be greatly overlooked.Royal Societ