We have cloned a novel member of the tandem pore K+ channel family from human brain cDNA. The novel cDNA encodes a 330-residue polypeptide of predicted molecular mass 36 kDa. We have named the channel TASK-5 owing to its sequence homology with TASK-1 and TASK-3. TASK-5 mRNA is expressed in pancreas, liver, kidney, lung, ovary, testis and heart. However, expression of TASK-5 in heterologous systems failed to elicit ionic currents. Removal of a putative endoplasmic reticulum retention sequence did not alter this finding and the distribution of channel proteins in HEK293 cells was similar for both TASK-1 and TASK-5. We tested whether TASK-5 could form heteromers with TASK-1. We show a mutant form of TASK-1 (H98N) to have a radically reduced sensitivity to acidification. Proton sensitivity could be rescued by injecting equimolar amounts of wild-type and mutant TASK-1 cRNA into Xenopus oocytes; the effect was that expected if half the channels formed are heteromers. Co-expression of TASK-5 with TASK-1 H98N does not affect the proton sensitivity of mutant TASK-1; thus TASK-5 appears not to form heteromers with TASK-1. Nonetheless, TASK-5 may require some other, unidentified partner subunit to form functional channels in the plasma membrane or it may form a channel in an intracellular organelle.

Field measurements of the vertical profiles of horizontal fluxes of airborne, sand‐sized soil aggregates are shown to be in good agreement with solutions of an equation that express the dependence of the concentration of sand at a given height on vertical diffusion and sedimentation. This approach treats sand as a diffusing agent rather than as projectiles that are affected by the wind only on the horizontal direction. The observed horizontal sand fluxes are shown to be in agreement with empirical formulas that express total horizontal flux of sand as a function of wind and soil parameters.

moved and the residual viscous red oil treated with 5 cc. of boiling petroleum ether (b. p. 60-110"). The insoluble dark gum was removed from the solution by decantation of the latter. On cooling, the petroleum ether deposited an orange-colored solid which weighed 235 mg. By concentrating the mother liquors, carefully discarding the red gum which formed regularly, another 540 mg. of this solid was obtained. The total yield was 775 mg. (26%). A sample was recrystallized from petroleum ether (Darco) to constant melting point; tiny needles, m. p. 146' (cor.). Anal. Calcd. for C~lH2604: C, 72.88; H, 7.89. Found: C, 73.55; H, 7.82.l-Hydroxy-J-n-amyl-9-rnethyl-6-dibenzopyrone.-A mixture of 235 mg. of 2,6-dimethoxy-4-n-amyl-5'-methyl-2'-carboxybiphenyl, 0.6 cc. of 48% hydrobromic acid, 1 cc. of glacial acetic acid, and 0.5 cc. of acetic anhydride was heated to reflux to dissolve the solid acid, and heating continued for four hours. After pouring into 20 cc. of water, the reaction mixture was extracted three times with ether and the organic layer washed thoroughly with saturated aqueous sodium bicarbonate and dried over magnesium sulfate. The solvent was removed and the oily residue was treated with boiling petroleum ether (b. p.

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