RESUMEN
Plants and fungi use light and other signals to regulate development, growth, and metabolism. The fruiting bodies of the fungus Phycomyces blakesleeanus are single cells that react to environmental cues, including light, but the mechanisms are largely unknown [1]. The related fungus Mucor circinelloides is an opportunistic human pathogen that changes its mode of growth upon receipt of signals from the environment to facilitate pathogenesis [2]. Understanding how these organisms respond to environmental cues should provide insights into the mechanisms of sensory perception and signal transduction by a single eukaryotic cell, and their role in pathogenesis. We sequenced the genomes of P. blakesleeanus and M. circinelloides and show that they have been shaped by an extensive genome duplication or, most likely, a whole-genome duplication (WGD), which is rarely observed in fungi [3-6]. We show that the genome duplication has expanded gene families, including those involved in signal transduction, and that duplicated genes have specialized, as evidenced by differences in their regulation by light. The transcriptional response to light varies with the developmental stage and is still observed in a photoreceptor mutant of P. blakesleeanus. A phototropic mutant of P. blakesleeanus with a heterozygous mutation in the photoreceptor gene madA demonstrates that photosensor dosage is important for the magnitude of signal transduction. We conclude that the genome duplication provided the means to improve signal transduction for enhanced perception of environmental signals. Our results will help to understand the role of genome dynamics in the evolution of sensory perception in eukaryotes.
Asunto(s)
Evolución Molecular , Duplicación de Gen , Genoma Fúngico , Mucor/genética , Phycomyces/genética , Transducción de Señal/genética , Luz , Mucor/efectos de la radiación , Familia de Multigenes , Percepción , Phycomyces/efectos de la radiación , Transcripción Genética/efectos de la radiaciónRESUMEN
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)
