General practice as a career: insights for workforce policy.

Australia's general practitioners are working fewer hours, and many are leaving medical practice. Little is known about when and why experienced mid- and late-career GPs move away from clinical practice. Although career downsizing is often seen as an abrogation of vocation, it may reflect a desire to broaden work experiences within a constrained set of options.

Mitochondrial biogenesis in early mouse embryos: expression of the mRNAs for subunits IV, Vb, and VIIc of cytochrome c oxidase and subunit 9 (P1) of H(+)-ATP synthase.

The mouse egg contains about 90,000 mitochondria which undergo a buildup of mitochondrial cristae and increase in respiratory activity during cleavage. The mitochondrial DNA does not replicate during preimplantation development but is transcribed actively from the two-cell stage onward (Pikó and Taylor, 1987: Dev Biol 123:364-374). To gain further insight into mitochondrial biogenesis, we have now determined the steady state amounts of the mRNAs for the cytochrome c oxidase (COX) subunits IV, Vb and VIIc and the H(+)-ATPase subunit 9 (P1) (all encoded by nuclear genes) in slot hybridization experiments of total RNA from oocytes and early embryos.

Sequence of a mouse embryo cDNA clone encoding proteolipid subunit 9 (P1) of the mitochondrial H(+)-ATP synthase.

A cDNA clone to an abundantly expressed mRNA in cleavage stage mouse embryos has been sequenced and identified as encoding subunit 9 (P1) of the mitochondrial H(+)-ATP synthase. The deduced amino acid sequence of the mature subunit 9 protein differs in a single residue from the corresponding rat, ovine, bovine and human subunits.