Interaction of non-histone chromosomal proteins HMG1 and HMG2 with DNA

Interaction between non-histone protein HMG1 or HMG2 and DNA has been studied by using thermal denaturation and circular dichroism (CD) spectroscopy. We have made the following observations. 1. The binding of each of these two proteins to DNA stabilizes the latter, as shown by an increase in melting temperature of 20 degrees C (from 45 degrees C to about 65 degrees C). 2. There are 6.0 amino acids/nucleotide in HMG1-bound DNA and 5.0 in HMGI-bound DNA which suggests that each HMB1 moleculae would cover about 20 base pairs of DNA and each HMG2 molecule would cover about 25 base pairs. 3. The alpha-helical content of these two non-histone proteins in the complexes, estimated from the CD value at 220 nm, is about one third to one half that of total proteins in calf thymus chromatin. 4. DNA conformation is distorted only slightly by the binding of protein HMG1 or HMG2. 5. Neither the melting nor the CD properties of HMG1-DNA or HMG2-DNA complexes differ substantially whether they are prepared by NaCl-gradient dialysis in urea or by direct mixing of protein and DNA at 0.15 M NaCl, followed by dialysis against the same buffer i.e. 0.25 mM EDTA (pH 8.0).     

Alterations of the enteric nervous system in neonatal necrotizing enterocolitis revealed by whole-mount immunohistochemistry

We report the results of a comprehensive search of Drosophila melanogaster DNA sequences in GenBank for di-, tri-, and tetranucleotide repeats of more than four repeat units, and a DNA library screen for dinucleotide repeats. Dinucleotide repeats are more abundant (66%) than tri- (30%) or tetranucleotide (4%) repeats. We estimate that 1917 dinucleotide repeats with 10 or more repeat units are present in the euchromatic D. melanogaster genome and, on average, they occur once every 60 kb. Relative to many other animals, dinucleotide repeats in D. melanogaster are short. Tri- and tetranucleotide repeats have even fewer repeat units on average than dinucleotide repeats. Our WorldWide Web site (http://www.bio.cornell.edu/genetics/aquadro/+ ++aquadro.html) posts the complete list of 1298 microsatellites (> or = five repeat units) identified from the GenBank search. We also summarize assay conditions for 70 D. melanogaster microsatellites characterized in previous studies and an additional 56 newly characterized markers.     

Morphine enhancement of sucrose palatability: analysis by the taste reactivity test

The ability of morphine to modify sucrose palatability was assessed by the taste reactivity test. In Experiment 1, rats were injected with morphine (0.0, 0.5, 2.0, and 10.0 mg/kg, subcutaneously), 30 min before receiving a 10-min intraoral infusion of 2% or 20% sucrose solution. A dose of 2.0 mg/kg morphine enhanced ingestive reactions elicited by both concentrations of sucrose solution. In Experiment 2, the interval between morphine pretreatment and the taste reactivity test was manipulated. Rats given 2.0 mg/kg morphine 30 or 120 min before testing displayed enhanced ingestive reactions elicited by 20% sucrose solution during the first 5 min of a 10-min test. The results support the hypothesis that morphine enhances the hedonic assessment of sucrose solution.