Accumulation of betalain (amaranthin) in the seedling of Amaranthus caudatus, var. viridis, is inducible by light. Since the apparent lag-phase of amaranthin accumulation after the onset of light is of the order of 3 h, light induction experiments could be performed up to 3 h after the onset of light without interference with actual synthesis. The intricate induction phenomena can be explained as follows: The inductive light operates through phytochrome and through a blue/UV photoreceptor ('cryptochrome'). A phytochrome-dependent 'High Irradiance Reaction' is of minor importance. However, there is a strong, specific interaction between the light effects mediated through phytochrome and cryptochrome in the sense that the 'extent of the reversible response' — (response obtained with a particular light treatment terminated with a saturating red light pulse) minus (response obtained with the same light treatment when terminated with a saturating 756 nm light pulse) — increases with increasing Pfr level and total fluence rate during the induction period. It is concluded that light induced amaranthin synthesis is, in fact, a convenient biochemical model system of photomorphogenesis in the case when phytochrome and cryptochrome operate simultaneously in mediating photomorphogenesis.
NOAA's National Ocean Survey (NOS) desires to improve or replace the hardware presently installed in their National Tide and Water Level Measurement Network. The stilling well, float and wire and punched paper tape have unacceptable data defect rates and high' costs. A study was undertaken to analyze these problems, survey the field of available sensor and recorder technologies, and through a cost effectiveness analysis recommend those most suitable to the NOS missions and constraints. This paper presents the results of that study in the areas of processor/controller and recorder. A companion paper deals with the sensor portion of the study. Discussed are the functional requirements imposed on a processor/controller/recorder to acquire, process, filter and record data, as well as the fault detection and operator interactions required. Presented are the alternative recording techniques considered and the results of the reliability, effectiveness and cost analyses per- formed. Recommended are a C-MOS microprocessor with a simplified operator interface and erasable UV PROM as a recording medium.
The introduction of inks that cured, rather than dried, brought a completely new solution to the problem of drying. Ink is physically a liquid and will only dry when excited by some form of radiation. This is available in two forms.
The repair of DNA double-strand breaks in Escherichia coli cells irradiated with γ rays occurs only after new proteins are synthesized in response to damage introduced in the genome DNA. One protein whose synthesis is thus induced is the recA protein, and previous work has shown that recA cells do not repair double-strand breaks. However, inducing recA protein by treating cells with nalidixic acid does not induce repair of double-strand breaks, so this repair requires more than the presence of the recA protein. When repair of double-strand breaks is blocked, the genome DNA is degraded by an endonuclease-like action. Evidence is presented to show that the inducible inhibition of DNA degradation after x-irradiation [Pollard, E. C. & Randall, E. P. (1973) Radiat. Res. 55, 265] is probably caused by the inducible repair of DNA double-strand breaks.