Ultraweak light emission from rat liver nuclei.

An extremely weak native light emission from rat liver nuclei was detected and studied using a highly sensitive single photon counting system. This emission is oxygen dependent and we attribute it to (per) oxidative processes. The effects of deuterium oxide and 1,4-diazabicyclo-[2.2.2] octane on the light emission suggests the possible involvement of singlet oxygen. The kinetic features of the underlying reactions including biphasic response to both oxygen and temperature changes, could be clearly discerned. Further study of this light emission can serve as a useful adjunct to biochemical investigations of oxidative processes which play an important role in mutation, carcinogenesis and aging.

Monitoring a mammalian nuclear membrane phase transition by intrinsic ultraweak light emission.

The first thermodynamic measurements of the intensity of light emission associated with native lipid peroxidation in a biological membrane are described. Kinetics of the radical chain reaction are shown to be sensitive to membrane structural phase and lipid dynamics. This is demonstrated by a novel measurement of a phase transition in the membrane of the intact mammalian nucleus. The apparent activation energies of lipid peroxidation in this system are also obtained for the first time. We suggest that this measurement may be more generally applicable as a method for monitoring membrane phase transitions.

Spectral resolution of long term (0.5-50 s) delayed fluorescence from spinach chloroplasts.

The emission spectrum of room temperature delayed fluorescence from spinach chloroplasts does not change during the period 0.5-50 s after the cessation of illumination. This provides experimental evidence that charge recombination processes originating in various charge pairs of photosystem II, and manifest as various kinetical components of long term delayed fluorescence, result in the excitation of the same emitters, as predicted by the charge recombination hypothesis.