Analysis of temperature‐mediated changes in the wine yeast Saccharomyces bayanus var uvarum. An oenological study of how the protein content influences wine quality

Saccharomyces bayanus var. uvarum plays an important role in the fermentation of red wine from the D.O. Ribera del Duero. This is due to the special organoleptic taste that this yeast gives the wines and their ability to ferment at low temperature. To determine the molecular factors involved in the fermentation process at low temperature, a differential proteomic approach was performed by using 2D‐DIGE, comparing, qualitatively and quantitatively, the profiles obtained at 13 and 25°C. A total of 152 protein spots were identified. We detected proteins upregulated at 13°C that were shown to be related to temperature stress, the production of aromatic compounds involved in the metabolism of amino acids, and the production of fusel alcohols and their derivatives, each of which is directly related to the quality of the wines. To check the temperature effects, an aromatic analysis by GC–MS was performed. The proteomic and “aromatomic” results are discussed in relation to the oenological properties of S. bayanus var. uvarum.     

Liver glycogen phosphorylase is upregulated in glioblastoma and provides a metabolic vulnerability to high dose radiation

Channelling of glucose via glycogen, known as the glycogen shunt, may play an important role in the metabolism of brain tumours, especially in hypoxic conditions. We aimed to dissect the role of glycogen degradation in glioblastoma (GBM) response to ionising radiation (IR). Knockdown of the glycogen phosphorylase liver isoform (PYGL), but not the brain isoform (PYGB), decreased clonogenic growth and survival of GBM cell lines and sensitised them to IR doses of 10–12 Gy. Two to five days after IR exposure of PYGL knockdown GBM cells, mitotic catastrophy and a giant multinucleated cell morphology with senescence-like phenotype developed. The basal levels of the lysosomal enzyme alpha-acid glucosidase (GAA), essential for autolysosomal glycogen degradation, and the lipidated forms of gamma-aminobutyric acid receptor-associated protein-like (GABARAPL1 and GABARAPL2) increased in shPYGL U87MG cells, suggesting a compensatory mechanism of glycogen degradation. In response to IR, dysregulation of autophagy was shown by accumulation of the p62 and the lipidated form of GABARAPL1 and GABARAPL2 in shPYGL U87MG cells. IR increased the mitochondrial mass and the colocalisation of mitochondria with lysosomes in shPYGL cells, thereby indicating reduced mitophagy. These changes coincided with increased phosphorylation of AMP-activated protein kinase and acetyl-CoA carboxylase 2, slower ATP generation in response to glucose loading and progressive loss of oxidative phosphorylation. The resulting metabolic deficiencies affected the availability of ATP required for mitosis, resulting in the mitotic catastrophy observed in shPYGL cells following IR. PYGL mRNA and protein levels were higher in human GBM than in normal human brain tissues and high PYGL mRNA expression in GBM correlated with poor patient survival. In conclusion, we show a major new role for glycogen metabolism in GBM cancer. Inhibition of glycogen degradation sensitises GBM cells to high-dose IR indicating that PYGL is a potential novel target for the treatment of GBMs.Subject terms: Cancer metabolism, CNS cancer     

Cytological effects of colchicine on the grasshopper neuroblast in vitro with special reference to the origin of the spindle

The effectiveness of colchicine in destroying or preventing the development of the spindle is determined by the concentration of the colchicine and the degree of development of the spindle at the time of exposure; the greater the concentration of colchicine, the greater will be its effectiveness in destroying the spindle or interfering with its development; the more completely the spindle is developed at the time of exposure to colchicine, the greater is the concentration of colchicine required to destroy it or prevent its further development.The series of changes in chromosome orientation that take place during the course of colchicine action, namely, approximation of centromeres, formation of “stars,” the breaking up of one “star” into several, and complete chromosome disorientation, represent successive stages in the destruction of the spindle.Destruction of the completely formed spindle is typically accompanied by the accumulation of the spindle material outside the diminishing spindle in a hyaline globule. Similarly, interference of colchicine with spindle development leads to the accumulation of the presumptive spindle material, i.e., the karyolymph, in one or more hyaline globules. It is suggested that colchicine does not destroy the spindle material but merely alters its molecular orientation, so that it comes to comprise a spherical mass with no mitotic function.Strong concentrations of colchicine cause middle and late prophase nuclei to revert to early prophase. Somewhat lower concentrations applied to late prophase nuclei occasionally delay the breakdown of the nuclear membrane without altering the rate of chromosome contraction. In greatly retarded late prophase nuclei the chromosomes lose their intranuclear orientation, which lends support to the concept that the centromeres normally maintain a fixed position within the nucleus.