Role of AGC kinases in plant growth and stress responses

AGC kinases are important regulators of cell growth, metabolism, division, and survival in mammalian systems. Mutation or deregulation of members of this family of protein kinases contribute to the pathogenesis of many human diseases, including cancer and diabetes. Although AGC kinases are conserved in the plant kingdom, little is known about their molecular functions and targets. Some of the best-studied plant AGC kinases mediate auxin signaling and are thereby involved in the regulation of growth and morphogenesis. Furthermore, certain members are regulated by lipid-derived signals via the 3-phosphoinositide-dependent kinase 1 (PDK1) and the kinase target of rapamycin (TOR), similar to its animal counterparts. In this review, we discuss recent findings on plant AGC kinases that unravel important roles in the regulation of plant growth, immunity and cell death, and connections to stress-induced mitogen-activated protein kinase signaling cascades.     

Influence of chlorpromazine on nuclear and cytoplasmic uptake of35S-methionine

Résumé Des rats ont été traités avec de la chlorpromazine et ont reçu en suite une seule injection de³⁵S-méthionine. Des radioautographies des coupes histologiques ont montré que la chlorpromazine a un effect inhibitoire dans la synthèse de la protéine nucléaire et cytoplasmatique. Les cellules qui ont une grande vitesse de synthèse protéique sont les plus affectées.

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This investigation was supported by grants from the Rockefeller Foundation and Conselho Nacional de Pesquisas.

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The authors wish to acknowledge the help of Prof. L. C. U.Junqueira for criticism and encouragement, and MissEdna Freymüller for her skilled technical assistance.     

Alsatian chemists in Paris in the 19th century: a network, a school?

During the nineteenth century French chemistry was marked by an outstanding number of Alsatian chemists whose scientific contributions cannot be ignored. Especially following the Franco-Prussian War, their regional origin was given a particular importance as a means of affirming their singularity on the French scientific scene. However, some questions may be raised: can we distinguish the Alsatians from other French chemists before 1870? Were they a homogeneous group sharing a common origin? The aim of this article therefore, is, to show that by their theoretical options within chemistry, their personal and professional relationships, as well as by their participation in various common initiatives, they organized themselves both formally and informally within the Parisian scientific community. Amongst these forms of organization the research school of Charles Adolphe Wurtz (1817-84) emerges as the nucleus of what we may envisage as a network of Alsatian chemists working in Paris, in the second half of the nineteenth century.     

RGM is a repulsive guidance molecule for retinal axons

Axons rely on guidance cues to reach remote targets during nervous system development. A well-studied model system for axon guidance is the retinotectal projection. The retina can be divided into halves; the nasal half, next to the nose, and the temporal half. A subset of retinal axons, those from the temporal half, is guided by repulsive cues expressed in a graded fashion in the optic tectum, part of the midbrain. Here we report the cloning and functional characterization of a membrane-associated glycoprotein, which we call RGM (repulsive guidance molecule). This molecule shares no sequence homology with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons in vitro, demonstrating its repulsive and axon-specific guiding activity.