BDNF and trkB mRNAs oscillate in rat brain during the light-dark cycle.

In this study, we investigated whether in basal conditions the different functional states occurring during a 24-h cycle are reflected by the expression of brain-derived neurotrophic factor (BDNF) and its receptor, trkB, in rat cerebral cortex and hippocampus. Using semiquantitative RT-PCR assay, the levels of both BDNF and trkB mRNAs were found to undergo significant variation in a 24-h period. The strongest variation was detected in the hippocampus, where the ratio between maximum and minimum levels was about 3.5 and 17.5 for BDNF and trkB, respectively. These findings provide the first evidence that, in the absence of any experimental manipulation, the expression of a neurotrophin and its receptor undergoes diurnal oscillation, possibly related to the physiological variations of the activity level.

Small acidic peptides from wheat germ chromatin. I. Isolation and biochemical characterization.

RNA synthesis in cell and cell-free systems is inhibited by a family of acidic, low molecular weight chromatin peptides (CPs). These peptides were extracted from deproteinized DNA of prokaryotic and eukaryotic cells, but the low yield of purified material by this procedure hinders efforts aimed at understanding their action mechanism in gene regulation. In this report we describe two purification methods of CPs from an easily available source, wheat germ. A comparison is made between the method starting from deproteinized DNA and the method from purified chromatin. The biological effects (inhibition of L1210 cell growth and DNA in vitro transcription) of CPs from wheat germ together with their chemical characteristics (molecular weight, amino acid composition and presence of phosphoserine) show strong homology with those of CPs from other sources. These results suggest a possible role of these chromatin peptides in controlling gene expression.