Selective induction of labour.

In a prospective study of 1000 consecutive primigravidae labour was induced on 95 occasions. None of 16 perinatal deaths and none of 4 cases of suspected brain damage occurred after prolonged pregnancy or pre-eclampsia. It is concluded that a low incidence of induction is compatible with good results and that enthusiasm for the statistical concept of high risk in obstetric practice should be reviewed in the interest of mothers and children as individuals.     

Events following prophage Mu induction.

Escherichia coli strains lysogenic for a thermoinducible Mu prophage (Mu cts62) undergo rapid lysis about 50 min after heat induction. Induction of Mu cts62 apparently causes damage to the host sequences in which Mu is inserted. The normal expression of A, BU, and X genes of Mu is needed for this specific deleterious effect on the prophage-containing host sequences. Mu deoxyribonucleic acid can be shown to reintegrate extensively at different sites on the host genome during the lytic cycle after prophage induction or after infection of sensitive cells by clear-plaque mutants of Mu. We estimate that approximately 10 copies of Mu deoxyribonucleic acid are inserted per chromosome during vegetative growth. The episome rescue method for detecting vegetative Mu deoxyribonucleic acid insertion, in which an episome is transferred from the lytically infected cells to F- receipient cells, can be applied to study Mu integration without requiring the host cells to survive. It also provides an easy system to isolate Mu insertions in transmissible episomes and plasmids.     

Signal transduction during C. elegans vulval induction.

Nematode proteins related to the human epidermal growth factor receptor and Ras proteins act in a common pathway to control cell fates in response to an inductive signal. Analysis of these gene products during C. elegans vulval induction allows detailed study of their function in the context of a developing organism.     

Baculovirus induction of a DNA polymerase.

The baculovirus, Autographa california nuclear polyhedrosis virus, induced a new aphidicolin-sensitive, alpha-like, DNA polymerase upon infection of the lepidopteran noctuid, Trichoplusia ni. The new virus-induced DNA polymerase could be separated from the host alpha-like polymerase by phosphocellulose chromatography. The two polymerases differed in their sensitivities to heat inactivation, high salt concentrations, and 0.1 M phosphate buffer.     

Neural induction. A bird's eye view

Since the discovery of the phenomenon of neural induction by Spemann and Mangold in 1924, considerable effort has been invested in identifying the signals produced by the organizer that are responsible for diverting the fate of cells from epidermal to neural. Substantial progress has been made only recently by the finding in amphibians that BMP4 is a neural inhibitor and epidermal inducer, and that endogenous antagonists of BMPs are secreted by the organizer. However, recent results in the chick point to the existence of other, upstream events required before BMP inhibition stabilizes neural fates. Here we take a critical view of the evidence for and against the view that BMP inhibition is a sufficient trigger for neural induction in different vertebrates.