Isolation and characterization of nuclear genes coding for subunits of the yeast ubiquinol-cytochrome c reductase complex.

Nuclear genes coding for the Mr 17 000, 14 000 and 11 000 subunits of the ubiquinol-cytochrome c reductase complex (complex III) in yeast have been isolated from a clone bank of yeast nuclear DNA by use of a mRNA hybridization-competition assay. This is based on our observations that levels of mRNAs for these subunits are much reduced during glucose repression and in cytoplasmic petite mutants and the procedure should be of general application for the isolation of other inducible or repressible genes coding for mRNAs present at low levels in the cell. A first characterization of the clones is presented. The genes are not closely linked in the genome and those coding for Mr 14 000 and 11 000 subunits are present in unique genomic environments, which suggests that there are only single copies of each in the nuclear genome.

Neonatal mortality and morbidity associated with preterm breech presentation.

A retrospective study was performed on 88 live-born preterm infants with breech presentation. The neonatal mortality (NNM) was 18.2%, and 13.3% after correction for congenital malformations incompatible with life. 62.5% were delivered vaginally, and 37.5% by cesarean section (CS). In spite of the fact that most CSs were done for indications associated with increased fetal and neonatal morbidity and mortality, overall morbidity was comparable in the two groups. Mortality was higher in the vaginal group. Entrapment of the fetal head (7.3% of vaginal deliveries) and prolapse of the cord (4.5%) were major complications of preterm breech delivery. They resulted in two cases of neonatal death (NND) and three cases of neonatal asphyxia. Prolapse of the cord was in all cases associated with footling presentation. The authors consider these results in favor of routine CS in preterm breech presentation.