Ultraweak emissions of developing Xenopus laevis eggs and embryos

Abstract

We measured ultraweak emissions of the Xenopus laevis eggs and embryos during normal development and under the influence of stress factors in a spectral range of 250 to 800 nm using a photomultiplier. The registered emissions were analyzed by several basic characteristics: mean intensity, histograms, kurtosis, linear trends, and Fourier spectra. We followed relationships between these parameters and developmental stage, as well as the number of individuals in optic contact with each other. The ultraweak emissions did not differ from the background at all developmental stages according to the mean intensity. But Fourier analysis revealed the reliable presence of a number of spectral lines of ultraweak emission, predominantly in the range of 10⁻²–50 Hz, in the embryos at developmental stages 2 to 11. The intensity of ultraweak emissions reliably decreased within the first 10 min after egg activation and fertilization, as well as in the case of optic interaction between groups of embryos. Sharp cooling, increase in osmotic medium pressure, and transfer in a Ca²⁺ and Mg²⁺-free medium induced a short term (∼1–5 min) increase in the mean intensity of ultraweak emission. We studied specific features of ultraweak emissions from different parts of the embryo. The intensity of emission from the animal part of early blastula exceeded those from the vegetal area and entire embryo. Separated fragments of the lateral ectoderm at the neurula stage had higher mean intensities of ultraweak emission than intact embryos at the same developmental stages.