Exposing the fitness contribution of duplicated genes

Duplicate genes from the whole-genome duplication (WGD) in yeast are often dispensable--removing one copy has little or no phenotypic consequence. It is unknown, however, whether such dispensability reflects insignificance of the ancestral function or compensation from paralogs. Here, using precise competition-based measurements of the fitness cost of single and double deletions, we estimate the exposed fitness contribution of WGD duplicate genes in metabolism and bound the importance of their ancestral pre-duplication function. We find that the functional overlap between paralogs sufficiently explains the apparent dispensability of individual WGD genes. Furthermore, the lower bound on the fitness value of the ancestral function, which is estimated by the degree of synergistic epistasis, is at least as large as the average fitness cost of deleting single non-WGD genes. These results suggest that most metabolic functions encoded by WGD genes are important today and were also important at the time of duplication.     

Genetic activity of mouse oocytes during in vitro "spontaneous" maturation]

Mouse oocytes, liberated from ovarian follicles, resume meiosis in the obligatory presence of Ca++. PHMPS exerts a toxic effect on this mechanism. m-RNA synthesis, in contrast to that of r-RNA. seems to be required during the first hours of maturation in order to ensure realization of the following steps: in addition the 2nd maturation period, corresponding to the first polar body extrusion, depends on the presence of proteins synthesized during the chromatin condensation process and germinal vesicle breakdown. We suggest that it might be a factor responsible for microtubule formation in metaphase I.     

Differential scanning calorimetry of rat liver mitochondria

Summary Differential scanning calorimetry was employed for studying rat liver mitochondria and extracted mitochondrial lipids. Endothermic transition in the range 15–40°C was detected for the whole mitochondria and between 10–20°C for the extracted lipids.Acknowledgment. This work was supported in part by Volkswagen Foundation A.Z. 11-2711.     

Forest dieback: Extent of damages and control strategies

Summary This paper starts from the generally accepted premise that forest dieback is a complex phenomenon caused by multiple stresses that are exerted by a host of contributing factors. It is argued that the rapidly proceeding forest dieback, as documented in the damage inventories, is in itself enough reason to warrant action. Therefore, at this late stage, this paper emphasizes the pressing need to introduce active control measures which will reduce pollution emission through more efficient use of fossil fuels, through abatement techniques at the source, and through substitution with less polluting sources.