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The kinetics of the formation of sulphur and peptidic radicals by warming, observed in sulphur-containing proteins, is studied by E.P.R. techniques on different kinds of conalbumin x-irradiated at liquid N 2 temperature. As Conalbumin can be obtained with two-, one- and no-iron ions, this type of experiment can help to clarify the mechanisms by which metal ions interact with the processes of radical conversion. The results show that the processes of the formation of the two stable radicals -NH- &#46 H-CO- and -CH 2 -S · , after the initial step of absorption of radiant energy, follow two different and non-interacting pathways.

KBr single crystals are investigated by means of photostimulated thermoluminescence from 50 to 250°K. The spectral range of photostimulation is 240-700mµ. No evidence of V band stimulation has been found; only electron traps are involved in the stimulation process. Filling of the traps occurs either through capture of photoelectrons from the conduction band, or by tunneling of electrons from excited F centers to neighbouring traps.

SummaryE.s.r. studies of the radiation effects in naturally-occurring amino-acids in the dry state are reported. Some magnetic properties of these irradiated materials are discussed and conclusions deduced about the kind and the distribution of the radiation stable damage. The results seem to question the significance of quantitative indices of radical yield, such as Gr.

Genetic information begins to be transcribed during early cleavage in amphibian embryos,(1,2) and the tempo of informational RNA synthesis increases gradually through cleavage and into the early blastula stage. Previous studies from this laboratory (3,4) have shown that at this point a remarkable, near embryo-wide acceleration of informational RNA synthesis occurs, resulting during the mid-tolate blastular period in at least a 20-fold increase in the rate of synthesis of heterogeneously sedimenting, DNA-like RNA.

DNA/RNA hybridization results with mRNAs from developing Xenopus embryos suggest that each mRNA molecule is internally heterogeneous, containing a main part transcribed from unique DNA and a covalently linked smaller part transcribed from a family of homogeneously repeated sequences.

In order to determine the possible influence of prosthetic groups on the radiation effects in glycoproteins, the radical yield of a group of such molecules and related carbohydrates was determined by the ESR technique. The results indicate the absence of any measureable radiation protection of the prosthetic groups. Some inferences on the nature of radicals induced both in proteins and in carbohydrates examined are also reported.