Isolation and Synthesis of a Bacterially Produced Inhibitor of Rosette Development in Choanoflagellates.

The choanoflagellate Salpingoeca rosetta is a microbial marine eukaryote that can switch between unicellular and multicellular states. As one of the closest living relatives of animals, this organism has become a model for understanding how multicellularity evolved in the animal lineage. Previously our laboratories isolated and synthesized a bacterially produced sulfonolipid that induces S. rosetta to form multicellular "rosettes." In this study, we report the identification of a bacterially produced inhibitor of rosettes (IOR-1) as well as the total synthesis of this molecule and all of its stereoisomers. Our results confirm the previously noted specificity and potency of rosette-modulating molecules, expand our understanding of the complex chemical ecology between choanoflagellates and rosette-inducing bacteria, and provide a synthetic probe template for conducting further mechanistic studies on the emergence of multicellularity.

Tumor glioneuronal formador de rosetas. Ejemplo poco frecuente de neoplasia del IV ventrículo / Rosette-forming glioneuronal tumor. A rare neoplasm of the fourth ventricle

Presentamos un caso de tumor glioneuronal formador de rosetas del iv ventrículo observado en un adolescente de 14 años, sin antecedentes clínicos de interés. El paciente presentó un cuadro de hidrocefalia obstructiva y se le detectó radiológicamente una lesión ocupante de espacio que afectaba al vermis cerebeloso y que obstruía el iv ventrículo. Los hallazgos histopatológicos mostraron un tumor de apariencia benigna, constituido por estructuras rosetoides centradas por un material fibrilar acidófilo. Dicho tumor fue positivo tanto para marcadores neuronales (sinaptofisina y enolasa) como gliales (PGFA). Tras la descripción, se comentan brevemente las principales características de esta rara entidad (AU)

We present a case of a rosette-forming glioneuronal tumour of the fourth ventricle in a 14-year-old with no relevant previous clinical history. The patient presented with hypertensive hydrocephalus and radiology revealed a space-occupying lesion affecting the cerebellar vermis and obstructing the fourth ventricle. The tumour was removed and was seen to have a benign appearance and to be formed of rosette-like structures composed of acidophilic fibrillary material. It was positive for neuronal markers (synaptophysin and enolase) and glial markers (GRAP). The main features of this rare entity are discussed (AU)