Jeb signals through the Alk receptor tyrosine kinase to drive visceral muscle fusion

The Drosophila melanogaster gene Anaplastic lymphoma kinase (Alk) is homologous to mammalian Alk, a member of the Alk/Ltk family of receptor tyrosine kinases (RTKs). We have previously shown that the Drosophila Alk RTK is crucial for visceral mesoderm development during early embryogenesis. Notably, observed Alk visceral mesoderm defects are highly reminiscent of the phenotype reported for the secreted molecule Jelly belly (Jeb). Here we show that Drosophila Alk is the receptor for Jeb in the developing visceral mesoderm, and that Jeb binding stimulates an Alk-driven, extracellular signal-regulated kinase-mediated signalling pathway, which results in the expression of the downstream gene duf (also known as kirre)--needed for muscle fusion. This new signal transduction pathway drives specification of the muscle founder cells, and the regulation of Duf expression by the Drosophila Alk RTK explains the visceral-mesoderm-specific muscle fusion defects observed in both Alk and jeb mutant animals.     

Modes of variation in alcohol dehydrogenase inDrosophila melanogaster

Zusammenfassung Neben zwei elektrophoretisch verschiedenen Varianten derDrosophila-Alkoholdehydrogenase kommen innerhalb dieser Varianten weitere Variationen vor, die sich in ihrer spezifischen Aktivität und Temperaturempfindlichkeit unterscheiden. Es wird daraus geschlossen, dass der Grad des Polymorphismus von Populationen grösser sei, als aufgrund elektrophoretischer Untersuchungen geschätzt wird.     

In vitro interaction of enkephalin with serum and chromaffin granule components

Summary Incubation of radioactively labeled enkephalin with serum components or chromaffin granule components in vitro provided evidence that there are specific constituents which bind enkephalins and may affect their degradation. Evidence for carboxy-terminal degradation was found.This work was supported by the NIH Grants NS-13201 and NS-00201.     

Immunocytochemical reaction of a haemocyanin antibody in the midgut gland ofNautilus (Cephalopoda,Tetrabranchiata)

The branchial gland of the dibranchiate cephalopods is described as the site of haemocyanin synthesis. Because there is no equivalent to this organ in tetrabranchiate cephalopods the localization of haemocyanin synthesis remained unknown for a long time. In this study we could confirm the conclusions from prelimnary investigations concerning the copper content of the midgut gland ofNautilus, which gave the first indications for a possible localization of haemocyanin synthesis in this organ. We developed a polyclonal antibody againstNautilus haemocyanin, tested its specificity, and used it on ultra-thin sections of the tissue of the midgut gland. It could be shown that there is a clear imunogold precipitation only on the triangular basal cells in the terminal alveoli. All the other types of cell in this organ were free of any immunoreactivity. It can be supposed that the triangular basal cells in the terminal alveoli of the midgut gland are the sites of haemocyanin synthesis inNautilus.     

Women and systems

Despite the increase in women entering the professional work force, there are still few in systems. Yet women are nurtured as systems thinkers and rely, routinely, on their holistic understanding of complex relationships to resolve dilemmas. Once they have acquired formal systems skills to complement this “natural” systems thinking, women have a powerful array of techniques to use to their advantage at work, in politics, and in academia. Since systems can benefit from the participation of women, and reciprocally, women can benefit from applying systems skills, we should encourage more women into systems and offer them support as colleagues.