DPI, a supposed selective agonist of inhibitory dopamine receptors, strongly increases rat diuresis through alpha-adrenergic receptor activation

The diuretic effect of dopamine (DA) was compared with that of other DA receptor stimulants in rats. While apomorphine (APO) and (±)N-n-propyl-norapomorphine (NPA) failed to increase urine excretion, (3, 4-dihydroxyphenylamino) -2-imidazoline (DPI), a supposed st$\text{i}$mulant of DA inhibitory receptors, exerted a far greater diuretic e$\text{f}$fect than DA itself. The diuretic effect of DA and that of DPI were antagonized by a-adrenergic receptor antagonists such as phentolamine and yohimbine and by bulbocapnine. In contrast, DA receptor blockers such as haloperidol, pimozide, sulpiride and ergometrine were totally ineffective. It is concluded that the diuretic effect of DA and DPI are mediated by stimulation of a-adrenergic receptors.     

Effect of inoculum rate on mycorrhizal growth responses in pot-grown onion and clover

Summary White clover and onion plants were grown from seed in pots of sandy loam above pads of mycorrhizal inoculum soil at 0.17–1.40 g/pot (equivalent to 250–2000 kg/ha) and harvested on four occasions. In sterilized soil increasing inoculum rates increased the onset and size of the mycorrhizal growth response of white clover. In unsterilized soil the indigenous mycorrhizal fungi greatly stimulated growth of both clover and onion. Nevertheless, all mycorrhizal inoculum rates further stimulated shoot growth in onion (92% increase over all harvests), while only the highest inoculum rate significantly stimulated clover growth (52% increase).     

Tyrosine-protein kinase inhibition in human erythrocytes by polyphosphoinositides (PIP and PIP2).

In human erythrocytes Ser/Thr- and Tyr-phosphorylations of cytoplasmic domain of band 3 are catalyzed by casein kinase I and Tyr-protein kinase respectively, both distributed between cytosol and membrane structures. The results reported here show that purified cytosolic Tyr-protein kinase activity, assayed on added substrates such as poly(Glu,Tyr)4:1 and isolated chymotryptic fragments of band 3 cytoplasmic domain (cdb3), is potently inhibited by PIP and even more by PIP2. Similar inhibitory effects are displayed by these polyphosphoinositides also on the endogenous Tyr-phosphorylation of band 3, when they are added to the isolated native membranes, thus suggesting their involvement in regulating in-vivo Tyr-phosphorylation of membrane proteins.     

Statistical properties of the variation at linked microsatellite loci: implications for the history of human Y chromosomes [published erratum appears in Mol Biol Evol 1997 Mar;14(3):354]

It has recently been suggested that observed levels of variation at microsatellite loci can be used to infer patterns of selection in genomes and to assess demographic history. In order to evaluate the feasibility of these suggestions it is necessary to know something about how levels of variation at microsatellite loci are expected to fluctuate due simply to stochasticity in the processes of mutation and inheritance (genetic sampling). Here we use recently derived properties of the stepwise mutation model to place confidence intervals around the variance in repeat score that is expected at mutation-drift equilibrium and outline a statistical test for whether an observed value differs significantly from expectation. We also develop confidence intervals for the time course of the buildup of variation following a complete elimination of variation, such as might be caused by a selective sweep or an extreme population bottleneck. We apply these methods to the variation observed at human Y-specific microsatellites. Although a number of authors have suggested the possibility of a very recent sweep, our analyses suggest that a sweep or extreme bottleneck is unlikely to have occurred anytime during the last approximately 74,000 years. To generate this result we use a recently estimated mutation rate for microsatellite loci of 5.6 x 10(-4) along with the variation observed at autosomal microsatellite loci to estimate the human effective population size. This estimate is 18,000, implying an effective number of 4,500 Y chromosomes. One important general conclusion to emerge from this study is that in order to reject mutation-drift equilibrium at a set of linked microsatellite loci it is necessary to have an unreasonably large number of loci unless the observed variance is far below that expected at mutation-drift equilibrium.