ARP1 in Golgi organisation and attachment of manchette microtubules to thenucleus during mammalian spermatogenesis

Actin related protein of vertebrate, Arp1, is a major component of the dyna ctin complex. To characterise and localise Arp1 during mammalian spermatoge nesis, polyclonal antibodies were raised against a human recombinant Arp1, Anti-Arp1 antibodies were used for western-immunoblotting, indirect immunof luorescence and immunoelectron microscopy. In round spermatids, Arp1 was de tected at the centrosome and at the Golgi apparatus. In elongated spermatid s, Arp1 was predominantly found alone microtubules of the manchette and at their site of attachment to the nuclear envelope. In maturing spermatids, A rp1 was still present in the pericentriolar material, but in testicular spe rmatozoa it was not detectable. These various localisations of Arp1 and the ir changes during spermatid differentiation suggest that the dynactin compl ex in association with dynein might contribute to several activities: the f unctional organisation of the centrosome and of the Golgi apparatus and the shaping of the nucleus by manchette microtubules.