Mapping the prion protein distribution in marsupials: insights from comparing opossum with mouse CNS

The cellular form of the prion protein (PrP(C)) is a sialoglycoprotein widely expressed in the central nervous system (CNS) of mammalian species during neurodevelopment and in adulthood. The location of the protein in the CNS may play a role in the susceptibility of a species to fatal prion diseases, which are also known as the transmissible spongiform encephalopathies (TSEs). To date, little is known about PrP(C) distribution in marsupial mammals, for which no naturally occurring prion diseases have been reported. To extend our understanding of varying PrP(C) expression profiles in different mammals we carried out a detailed expression analysis of PrP(C) distribution along the neurodevelopment of the metatherian South American short-tailed opossum (Monodelphis domestica). We detected lower levels of PrP(C) in white matter fiber bundles of opossum CNS compared to mouse CNS. This result is consistent with a possible role for PrP(C) in the distinct neurodevelopment and neurocircuitry found in marsupials compared to other mammalian species

Light regulation of metabolic pathways in fungi

Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes

Blue-light regulation of phytoene dehydrogenase (carB) gene expression in Mucor circinelloides.

The carB gene, encoding the phytoene dehydrogenase of Mucor circinelloides, was isolated by heterologous hybridisation with a probe derived from the corresponding gene of Phycomyces blakesleeanus. The cDNA and genomic copies complemented phytoene dehydrogenase defects in Escherichia coli and in carB mutants of M. circinelloides, respectively. Fluence-response curves for transcript accumulation were constructed after different blue-light pulses. The level of carB mRNA accumulation reached values up to 150-fold higher than basal levels in darkness. Several elements in the promoter of this gene resemble a consensus sequence identified in Neurospora crassa (APE) which is essential for blue-light regulation. Comparison of the available phytoene dehydrogenase sequences from plants, fungi, algae and bacteria suggests that the two known types of phytoene dehydrogenase are more closely related to each other than previously thought