Defining the molecular structure and function of synapses is a central theme in brain research. In Drosophila the Bruchpilot (BRP) protein is associated with T-shaped ribbons (“T-bars”) at presynaptic active zones (AZs). BRP is required for intact AZ structure and normal evoked neurotransmitter release. By screening for mutations that affect the tissue distribution of Bruchpilot, we have identified a P-transposon insertion in gene CG11489 (location 79D) which shows high homology to mammalian genes for SR protein kinases (SRPKs). SRPKs phosphorylate serine-arginine rich splicing factors (SR proteins). Since proteins expressed from CG11489 cDNAs phosphorylate a peptide from a human SR protein in vitro, we name CG11489 the Drosophila Srpk79D gene. We have characterized Srpk79D transcripts and generated a null mutant. Mutation of the Srpk79D gene causes conspicuous accumulations of BRP in larval and adult nerves. At the ultrastructural level, these correspond to extensive axonal agglomerates of electron-dense ribbons surrounded by clear vesicles. Basic synaptic structure and function at larval neuromuscular junctions appears normal, whereas life expectancy and locomotor behavior of adult mutants are significantly impaired. All phenotypes of the mutant can be largely or completely rescued by panneural expression of SRPK79D isoforms. Isoform-specific antibodies recognize panneurally overexpressed GFP-tagged SRPK79D-PC isoform co-localized with BRP at presynaptic active zones while the tagged -PB isoform is found in spots within neuronal perikarya. SRPK79D concentrations in wild type apparently are too low to be revealed by these antisera. We propose that the Drosophila Srpk79D gene characterized here may be expressed at low levels throughout the nervous system to prevent the assembly of BRP containing agglomerates in axons and maintain intact brain function. The discovery of an SR protein kinase required for normal BRP distribution calls for the identification of its substrate and the detailed analysis of SRPK function for the maintenance of nervous system integrity.

We report about a successful heart failure therapy with carvedilol in two children with neonatal Marfan syndrome (nMFS). As shown in Case 1, double valve replacement in an infant with neonatal Marfan syndrome is feasible but its benefit on long term is uncertain. Excluding our patient, 3 infants with nMFS from the literature died early after cardiac surgery. Our second case is a unique patient who survives nMFS despite diaphragmatic herniae, dilated neonatal cisterna magna and severe atrioventricular valve insufficiencies. Treated with 0.7 mg/kg/day Carvedilol since his seventh month of life, he never developed severe heart failure. However despite his good health status at the age of 9 years, a progressive aortic root dilatation and left conornary aneurysm are still waiting for surgical repair.