Mos limits the number of meiotic divisions in urochordate eggs.

Mos kinase is a universal mediator of oocyte meiotic maturation and is produced during oogenesis and destroyed after fertilization. The hallmark of maternal meiosis is that two successive M phases (meiosis I and II) drive two rounds of asymmetric cell division (ACD). However, how the egg limits the number of meioses to just two, thereby preventing gross aneuploidy, is poorly characterized.

Inactivation of MAPK in mature oocytes triggers progression into mitosis via a Ca2+ -dependent pathway but without completion of S phase.

Unfertilized sea urchin eggs that are arrested at G1 phase after completion of meiosis contain a highly phosphorylated mitogen-activated protein (MAP) kinase (MAPK), the ERK-like protein (ERK-LP). Several data including our previous results show that ERK-LP is inactivated after fertilization, which agrees with results obtained in other species including Xenopus, starfish and mammals. The question is to elucidate the function of a high MAPK activity in sea urchin eggs.

Jupiter, a new Drosophila protein associated with microtubules.

In this study we describe a novel Drosophila protein Jupiter, which shares properties with several structural microtubule-associated proteins (MAPs) including TAU, MAP2, MAP4. Jupiter is a soluble unfolded molecule with the high net positive charge, rich in Glycine. It possesses two degenerated repeats around the sequence PPGG, separated by a Serine-rich region.

A MAPK pathway is involved in the control of mitosis after fertilization of the sea urchin egg.

Activation and role of mitogen-activated protein (MAP) kinase (MAPK) during mitosis are still matters of controversy in early embryos. We report here that an ERK-like protein is present and highly phosphorylated in unfertilized sea urchin eggs. This MAPK becomes dephosphorylated after fertilization and a small pool of it is transiently reactivated during mitosis.

Two anti-radial spoke monoclonal antibodies inhibit Chlamydomonas axonemal motility by different mechanisms.

In the 9 + 2 axoneme, radial spokes are structural components attached to the A-tubules of the nine outer doublet microtubules. They protrude toward the central pair microtubule complex with which they have transient but regular interactions for the normal flagellar motility to occur. Flagella of Chlamydomonas mutants deficient in entire radial spokes or spoke heads are paralyzed.

Effects of methoxychlor, dieldrin and lindane on sea urchin fertilization and early development.

We have studied the effects of methoxychlor (MXC), dieldrin, and lindane on fertilization and early development of sea urchin egg. These organochlorine pesticides have often been found in polluted ground and water near agricultural sites, and have therefore been detected from time to time in the food chain and in drinking water. They have been reported to alter various reproduction functions in various animals including marine populations.

Differential distribution of glutamylated tubulin isoforms along the sea urchin sperm axoneme.

Tubulin belongs to a highly conserved multigenic family, in which several gene products usually coexist in the same tissue or the same cell. Moreover, seven classes of post-translational modifications of these gene products lead to an amazing diversity of tubulin polypeptide chains, within the same cell type, whose physiological function remains elusive. Such diversity has been found in a very stable microtubular organelle, the sea urchin sperm flagellum, where some tubulin isoforms have been directly implicated in motility, whereas others may play a more structural role.