ACTIVIN BETA(A) SUBUNIT IS EXPRESSED IN BOVINE OVIDUCT

It is evident that members of several growth factor families are activ ely involved in embryogenesis from its earliest phases. Several report s also indicate the oviduct as a possible source of growth factors, su ggesting an active role of this organ in mammalian embryonic developme nt. The aim of this study was to investigate the presence of activin/i nhibin subunits in bovine oviduct since activin is a well-characterise d morphogen in amphibian development. The presence of transcripts for alpha, beta(A), and beta(B) subunits was investigated by analysing ovi duct epithelial cells mRNA with reverse transcription-polymerase chain reaction (RT-PCR). Moreover, antisera specific for the three subunits were used for the Western blot analysis of the proteins secreted by o viduct epithelial cells in vitro and for their immunohistochemical loc alisation in different oviductal regions. Oviduct epithelial cells exp ressed only the beta(A)-subunit gene. Immunoreactive material was pres ent among in vitro secreted proteins, indicating that the transcript i s translated into a polypeptide that has been localised in the epithel ium of both the ampullary and isthmic tract of the organ. Consistent w ith these results, the antisera for the alpha and beta(B) subunits did not recognise any specific antigen either among secreted proteins or in the sections. These results indicate that beta(A) subunit gene is e xpressed in bovine oviduct epithelial cells, and the protein is secret ed in vitro and can be found along the whole extension of the organ. I n the absence of alpha or beta(B) subunits, this suggests that activin A is present in bovine oviduct, Such a finding would be consistent wi th an embryotrophic activity of this organ, but definitive conclusions on the target tissue and the specific functions of oviductal activin require further studies. (C) 1995 Wiley-Liss, Inc.