Dynamic behavior of CO2 uptake as affected by light: system identification based on spectral analysis

Summary The dynamic behavior of CO₂ uptake in sunflower plants was measured in a computer controlled apparatus and identified systematically using spectral analysis.To obtain impulse responses of net CO₂ uptake, power spectra were estimated by the Fast Fourier Transform (FFT) method. FFT was done by computing 512 separate data points sampled at one minute intervals. From examination of coherency, it was determined that dynamic behavior of CO₂ uptake could be estimated by linear filtering based on impulse response as affected by the light in changes slower than 0.08 cycle min^-1. This suggests that other dynamic phenomena in physiological ecology could be estimated effectively by using advanced system theory involving many algorithms.     

Aromatization of norethindrone to ethynylestradiol in human adult liver [Poster 41]

Homogenates of human adult liver are capable of aromatizing norethindrone (17-ethynyl-19-nortestosterone) to ethynylestradiol (17-ethynylestradiol). The evidence of ethynylestradiol formation was obtained using a Bio-Rad AG1-X2 column, thin-layer chromatography and co-crystallization.     

Newt RAD51: Cloning of cDNA and analysis of gene expression during spermatogenesis

A cDNA encoding a newt homolog of Escherichia coli RecA and yeast RAD51 from a testis cDNA library was isolated. The newt RAD51 (nRAD51) cDNA predicted a 337 amino acid protein with a 95-96% amino acid identity to Xenopus and mammalian RAD51. Northern blot analysis showed that nRAD51 mRNA, 1.7 kb in length, was expressed strongly in the testis and ovary, but weakly in the liver, kidney and brain. In situ hybridization revealed that expression of nRAD51 mRNA was barely observed in primary spermatogonia (one cell in a cyst) and early secondary spermatogonia (two to four cells in a cyst), but increased in late secondary spermatogonia (> or =eight cells in a cyst), reaching a maximum level in leptotene-zygotene spermatocytes, and thereafter declined. These results suggest that nRAD51 is involved in mitotic recombination in spermatogonia as well as in meiotic recombination in spermatocytes.