Distribution of corticotropin-releasing factor in ovine brain determined by radioimmunoassay

We have developed and used a sensitive and specific radioimmunoassay to demonstrate the presence of CRF-like immunoreactivity in extra-hypothalamic areas of ovine brain. Synthetic CRF displaced antibody bound tracer at an ED50 value of 200 pg and there was no cross-reactivity with LHRH, TRH, ACTH, beta-endorphin and several other peptides. Displacement of bound 125I-CRF by brain extracts exhibited curves parallel to synthetic CRF standards. Highest concentrations (1 ng/mg tissue) of CRF-like immunoreactivity were found in the median eminence but surprisingly, high concentrations of CRF-like immunoreactivity were found in frontal, parietal, occipital and particularly temporal areas of cerebral cortex. Much lower concentrations were found in other brain areas including the basal ganglia, limbic system and brain stem.     

DNA and histone H1 interact with different domains of HMG 1 and 2 proteins.

High mobility group (HMG) proteins 1 and 2 from calf thymus have been digested under structuring conditions (0.35 M NaCl, pH 7.1) with two proteases of different specificities, trypsin and V8. The two proteases give a different but restricted pattern of peptides in a time course digestion study. However, when the interactions of the peptides with DNA are studied by blotting, a closely related peptide from HMG-1 and -2 does not show any apparent binding. This peptide, from the V8 protease digestion, has been isolated by DNA-cellulose chromatography and has the amino acid composition predicted for a fragment containing the two C-terminal domains of the protein, i.e., approximately residues 74-243 for HMG-1. The same peptide shows the only interaction detectable with labelled histone H1. A separate function for the different domains of HMG proteins 1 and 2 is proposed.     

Influence des héméropériodes très courtes sur la croissance de Lolium multiflorum,sa composition pigmentaire et l'ultrastructure chloroplastique

Summary We have described some characteristics of Lolium multiflorum cultivated under very short photoperiods (2 hours and 1 hour). The estimations of leaf growth were based on dry weight, surface measurements, and chlorophyll content. The pigment analyses were carried out by column chromatography; chloroplast ultrastructure was observed after chemical fixation.These measurements have permitted us to note a sharp drop in the growth curve of plants grown under different day-lengths: the limiting photoperiod lies between 1 hour and 2 hours of daily illumination.Pigment analyses and chloroplast ultrastructure observations show that there is a greater difference between plants cultivated under 1 hour and 2 hours of daily illumination than between plants cultivated under 2 hours and 12 hours.A decrease in day-length causes a deficit in the chlorophyll b content as well as a poor development of the grana.We have attempted to correlate these structural anomalies with the abnormal chlorophyll a/chlorophyll b ratio.