A voluntary conservation agreement reduces the risks of lethal collisions between ships and whales in the St. Lawrence Estuary (Québec, Canada): From co-construction to monitoring compliance and assessing effectiveness.

Lethal collisions with ships are limiting the recovery of several at-risk whale species worldwide. In the St. Lawrence Estuary (Quebec, Canada), the endangered blue whale and of special concern fin whale are among the migratory species subject to collisions with large ships.

Three dimensional configuration of the secretory pathway and segregation of secretion granules in the yeast Saccharomyces cerevisiae.

The structural elements of the secretory pathway in the budding yeast Saccharomyces cerevisiae were analyzed by 3D stereo-electron microscopy using relatively thick sections in which membranes were selectively impregnated. In a wild-type strain, tubular networks of various sizes and staining properties were distributed throughout the cytoplasm. As a rule, wide-meshed, lightly stained polygonal networks were connected to more or less fenestrated sheets of endoplasmic reticulum (ER).

Effects of in vivo exposure of Mya arenaria to organic and inorganic mercury on phagocytic activity of hemocytes.

Marine bivalves are aquatic invertebrate organisms which can be used as bioindicators in environmental monitoring. In vivo effects of mercuric chloride (HgCl(2)) and methylmercury (CH(3)HgCl) on phagocytic function of Mya arenaria hemocytes were evaluated in this study. Clams were exposed to single metal in water for up to 28 days at concentrations ranging from 10(-9) to 10(-5) M.

Role of endoplasmic reticulum-derived vesicles in the formation of Golgi elements in sec23 and sec18 Saccharomyces Cerevisiae mutants.

Background: In the yeast Saccharomyces cerevisiae, the Golgi apparatus consists of individual networks of membranous tubules interspersed throughout the cytoplasm. When sec23 and sec18 mutants are shifted from the permissive (20 degrees C) to the restrictive (37 degrees C) temperature, the secretory pathway is blocked between endoplasmic reticulum (ER) and Golgi elements. When examined with an electron microscope, sec23 displays an excess of ER membranes, whereas sec18 accumulates small vesicles.

Impaired fertility in mice deficient for the testicular germ-cell protease PC4.

PC4 is a member of the proprotein convertase family of serine proteases implicated in the processing of a variety of polypeptides including prohormones, proneuropeptides, and cell surface proteins. In rodents, PC4 transcripts have been detected in spermatocytes and round spermatids exclusively, suggesting a reproductive function for this enzyme. In an effort to elucidate this function, we have disrupted its locus (Pcsk4) by homologous recombination in embryonic stem cells and have produced mice carrying the mutation.