Pre-M Phase-promoting Factor Associates with Annulate Lamellae in Xenopus Oocytes and Egg Extracts

We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising "annulate lamellae" (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates

Determinants of the success of international assignees as knowledge transferors: a theoretical framework

Drawing on previous work in the knowledge management literature, this article develops a conceptual framework to analyse the cause and effects of international assignments as a knowledge transfer mechanism. In examining the characteristics of knowledge transferred within multinational companies (MNCs) the use of international assignees is explained and justified. The article also identifies the factors influencing the success of international assignees as knowledge transferors. It is argued that, in addition to the specific characteristics of the knowledge involved, transfer success will be affected by three sets of human-related factors: abilities and motivation of international staff; abilities and motivation of local employees; and the relationship between local and international staff. The article concludes by discussing some management initiatives helping to trigger the human-related factors