Biosynthesis of aflatoxins by cell-free preparations fromAspergillus flavus

Résumé Incorporation d'acétate-1-¹⁴C, de leucine-U-¹⁴C et de mévalonate-2-¹⁴C sous forme d'aflatoxine dans les extraits libres des cellulesd'Aspergillus flavus. Dans le cas du mévalonate, l'incorporation de l'ordre de 0,4 pour 100 et les activités spécifiques sont 13 000 à 40 000 cpm/mg d'aflatoxine. La capacité d'incorporation des substrats en aflatoxine s'observe, en particulier, dans les mitochondries.     

Topographic localisation of insulinogenic and insulinoprival areas in the hypothalamus

Summary Electrical stimulation of hypothalamic areas through stereotaxically implanted electrodes were carried out in conscious male rhesus monkeys. There was a significant increase in immunoreactive insulin (IRI) following lateral hypothalamus (LHA) stimulation. An opposite response was obtained from ventromedial hypothalamus (VMH). Thus, insulinogenic and insulinoprival responses were obtained from feeding and satiety, suggesting a significant role of insulin in the regulation of food intake.     

Virus-mediated killing of cells that lack p53 activity

A major goal of molecular oncology is to identify means to kill cells lacking p53 function. Most current cancer therapy is based on damaging cellular DNA by irradiation or chemicals. Recent reports support the notion that, in the event of DNA damage, the p53 tumour-suppressor protein is able to prevent cell death by sustaining an arrest of the cell cycle at the G2 phase. We report here that adeno-associated virus (AAV) selectively induces apoptosis in cells that lack active p53. Cells with intact p53 activity are not killed but undergo arrest in the G2 phase of the cell cycle. This arrest is characterized by an increase in p53 activity and p21 levels and by the targeted destruction of CDC25C. Neither cell killing nor arrest depends upon AAV-encoded proteins. Rather, AAV DNA, which is single-stranded with hairpin structures at both ends, elicits in cells a DNA damage response that, in the absence of active p53, leads to cell death. AAV inhibits tumour growth in mice. Thus viruses can be used to deliver DNA of unusual structure into cells to trigger a DNA damage response without damaging cellular DNA and to selectively eliminate those cells lacking p53 activity.     

Effect of piperazine on the level of phospholipids and on the activities of certain enzymes of phospholipid metabolism in humanAscaris lumbricoides

Summary The phospholipid level in the human parasitic nematodeAscaris lumbricoides is decreased by piperazine, by partially stimulating catabolic enzymes such as phospholipase C and partially inhibiting anabolic enzymes such as choline kinase.Acknowledgment. We thank ProfessorP. A. Kurup of this Department for keen interest and helpful advice.