Analysis of the protein composition of the spindle pole body during sporulation in Ashbya gossypii.

The spores of fungi come in a wide variety of forms and sizes, highly adapted to the route of dispersal and to survival under specific environmental conditions. The ascomycete Ashbya gossypii produces needle shaped spores with a length of 30 µm and a diameter of 1 µm. Formation of these spores relies on actin and actin regulatory proteins and is, therefore, distinct from the minor role that actin plays for spore formation in Saccharomyces cerevisiae. Using in vivo FRET-measurements of proteins labeled with fluorescent proteins, we investigate how the formin AgBnr2, a protein that promotes actin polymerization, integrates into the structure of the spindle pole body during sporulation. We also investigate the role of the A. gossypii homologs to the S. cerevisiae meiotic outer plaque proteins Spo74, Mpc54 and Ady4 for sporulation in A. gossypii. We found highest FRET of AgBnr2 with AgSpo74. Further experiments indicated that AgSpo74 is a main factor for targeting AgBnr2 to the spindle pole body. In agreement with these results, the Agspo74 deletion mutant produces no detectable spores, whereas deletion of Agmpc54 only has an effect on spore length and deletion of Agady4 has no detectable sporulation phenotype. Based on this study and in relation to previous results we suggest a model where AgBnr2 resides within an analogous structure to the meiotic outer plaque of S. cerevisiae. There it promotes formation of actin cables important for shaping the needle shaped spore structure.

Contact tracing following measles exposure on three international flights, Germany, 2017.

When a person with contagious measles has travelled by aircraft, European guidelines recommend contact tracing of passengers and crew within 5 days of exposure for post-exposure prophylaxis (PEP), and within 12 days of exposure for informing passengers and crew, in order to prevent further transmissions. To be effective, contact tracing requires prompt diagnosis, immediate notification of public health authorities and rapid availability of passenger contact data. We report two events of contact tracing initiated in Germany after two individuals with measles travelled on three international flights. In one event, contact tracing was initiated late because laboratory confirmation of a clinically diagnosed measles case was awaited unnecessarily. Accessing passenger contact data was difficult in both events because of data protection issues with the airline which was not based in Germany. In both events, passengers were not reached in time to provide PEP, and one event resulted in at least two secondary measles cases. As all passengers were reached before the incubation period ended, tertiary cases were most probably prevented. Public health authorities and the transport sector must collaborate to resolve competing legal regulations for infection prevention and data protection, to simplify and accelerate identification of air travellers exposed to communicable diseases.

The small GTP-binding proteins AgRho2 and AgRho5 regulate tip-branching, maintenance of the growth axis and actin-ring-integrity in the filamentous fungus Ashbya gossypii.

GTPases of the Rho family are important molecular switches that regulate many basic cellular processes. The function of the Rho2 and Rho5 proteins from Saccharomyces cerevisiae and of their homologs in other species is poorly understood. Here, we report on the analysis of the AgRho2 and AgRho5 proteins of the filamentous fungus Ashbya gossypii. In contrast to S. cerevisiae mutants of both encoding genes displayed a strong morphological phenotype. The Agrho2 mutants showed defects in tip-branching, while Agrho5 mutants had a significantly decreased growth rate and failed to maintain their growth axis. In addition, the Agrho5 mutants had highly defective actin rings at septation sites. We also found that a deletion mutant of a putative GDP-GTP-exchange factor (GEF) that was homologous to a Rac-GEF from other species phenocopied the Agrho5 mutant, suggesting that both proteins act in the same pathway, but the AgRho5 protein has acquired functions that are fulfilled by Rac-proteins in other species.