Expression of maternal and paternal histone genes during early cleavage stages of the echinoderm hybrid Strongylocentrotus purpuratus x Lytechinus pictus.
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Biomedical subjects
R E Maxson
Publications and source records attributed to R E Maxson.
Fast axoplasmic transport of noradrenaline and dopamine in mammalian peripheral nerve.
A fast transport of noradrenaline (NA) at a velocity of 392 mm/day was found in cat peroneal nerve using a double-ligation technique and a new sensitive radioenzymatic assay for catecholamines. The velocity of transport of NA is sufficiently close to that of 410 mm/day found for labelled proteins and polypeptides to be considered as moving down within the nerve fibres by the same transport mechanism. In addition, dopamine (DA) was also found to be moved down by anterograde transport at a fast, but not well defined, rate. Disulfiram, a dopamine-beta-hydroxylase inhibiting agent, reduced NA levels and increased DA both in control nerve segments and within the portion of the nerve isolated by ligations where NA-containing densecore vesicles are present. The results are considered to support a dynamic turnover of NA and DA in the dense-core vesicles as they are trasnported in the axons.
Animals↗
Elevation of dopamine in fetal plasma and the amniotic fluid during gestation.
Catecholamines were determined by a radioenzymatic assay in maternal and fetal rat plasma and in the amniotic fluid during the last five days of gestation. Dopamine was significantly higher in fetal than in maternal plasma whereas norepinephrine was the same. Epinephrine was sighificantly lower in fetal than in maternal plasma on days 18 and 19, but was the same during the remainder of gestation. Dopamine was the predominant catecholamine in the amniotic fluid on days 20-22 of gestation showing the largest percent increase prior to parturition. The data suggest that dopamine may have a peripheral hormonal role during fetal development and parturition.
Amniotic Fluid↗
A simple method for measuring specific radioactivities of ribonucleoside triphosphates using RNA polymerase.
We describe a method for the rapid, one-step determination of the specific radioactivity and pool size of ATP, UTP, CTP or GTP. Escherichia coli RNA polymerase and poly[d(A-T)] or poly[d(G-C)] are used to synthesize an alternating copolymer from a [3H]nucleoside triphosphate of unknown specific activity and a [14C]nucleoside triphosphate of known specific activity. The fact that [3H]nucleotide and [14C]nucleotide are incorporated into poly[r(A-U)] or poly[r(G-C)] in equimolar amounts, coupled with a knowledge of the [14C]nucleotide specific activity, permits calculation of the [3H]nucleotide specific activity. The requirement for direct knowledge of the [14C]nucleotide specific activity may be bypassed by an isotope dilution procedure. The pool size of a nucleoside triphosphate can be estimated either from isotope dilution data or by determining the fraction of [3H]nucleotide polymerized, dividing the number of counts 3H/min in the polymer by this fraction and by the [3H]nucleotide specific activity. The method was successfully applied to acid extracts made from sea urchin embryos labeled with a [3H]RNA precursor.
Animals↗