Cloning and expression of the human and rat m5 muscarinic acetylcholine receptor genes

The human and rat genes for a fifth muscarinic receptor have been cloned and expressed in mammalian cells. The 532 amino acid human protein has 89% sequence identity to the 531 amino acid rat protein and is most closely related to the m3 receptor. Both proteins are encoded by single exons. The receptor has intermediate affinity for pirenzepine and low affinity for AF-DX 116, and it increases metabolism of phosphatidylinositol when stimulated with carbachol. Expression of mRNA has yet to be observed in brain or selected peripheral tissues, suggesting that either it is substantially less abundant than m1-m4 or its distribution is quite different.     

Natural selection in House mice (Mus musculus) from South Georgia (South Atlantic Ocean)

Mice living in tussock grass on a remote headland of the South Atlantic island of South Georgia (54°S) where the mean temperature is less than 2°C and the monthly average below 0°C for four months each year have been studied. They are big animals (although not as large as those on some North Atlantic islands) and have much brown fat, showing their response to their cold environment. Only two out of 27 gene loci scored electrophoretically were segregating (3·4% heterozygosity); these ( Es-6, Got-2 ) are four cross-over units apart on chromosome 8, and were in strong linkage disequilibrium. There were marked changes in allele frequencies with age which go in opposite directions in males and females, showing the action of stabilizing selection: Es-6 ^a increased from 16% in males of less than three months, to 35% in older animals; it declined in females from 36 to 19%.     

Daily changes in the sensitivity of wax-moth larvae, Galleria mellonella, to cooling stress

ABSTRACT. Sensitivity to cooling stress in the last instar larvae of Galleria mellonella was measured as (a) the number of extra larval moults, (b) the number of larvae retaining the ability to secrete silk, and (c) the number showing arrested development. With respect to (a) and (b) there were considerable differences in sensitivity across the day. A relationship was observed between the number of additional larval moults induced by chilling and the ability of prepupal larvae to spin silk: the periods during the 24 h when the most larvae passed through additional larval moults were periods characterized by the smallest number of larvae capable of spinning, and vice versa. These daily changes were apparently partly independent of developmental age. Daily variations in sensitivity also occurred when larvae of the same age were cooled at different times of day. It is suggested that these rhythms in cold-sensitivity are related to a cold-sensitive rhythm in juvenile hormone secretion, or hormone sensitivity in the tissues.     

Ecdysone-stimulated RNA synthesis in imaginal discs of Drosophila melanogaster

Cytoplasmic RNA from imaginal discs of Drosophila melanogaster, labeled by uridine incorporation in organ culture, has been assayed by hybridization to cytological preparations of polytene chromosomes. RNA labeled during the early stages (first four hours) of ecdysone stimulation was compared to RNA labeled in the absence of the hormone. For the poly(A)-containing fraction (oligo-dT bound), several loci hybridize only RNA labeled in the presence of ecdysone; one locus hybridizes only control RNA. The majority of hybridizing loci are unaffected by the hormone. Of the loci hybridizing RNA not bound to oligo-dT, several appear specific for the ecdysone-treated sample, though most are labeled more heavily with this RNA than with the control. None of the ecdysone-sensitive loci visualized by in situ hybridization are the sites of salivary gland puffs induced by ecdysone on the same time scale.     

Analyses of the returned lunar surface fines for porphyrins

In the present studies, no porphyrins were found in the lunar surface fines collected from the Sea of Tranquillity by the Apollo 11 mission, from the Ocean of Storms by the Apollo 12 mission, and from the nonmare Fra Mauro Formation by the Apollo 14 expedition under the conditions in which porphyrins would have been detected had they been present in amounts as small as 10^–14 mole.     

Acid-catalysed monoacetalation of some 2-deoxyalditols

Acid-catalysed monobutylidenation of 2-deoxy-D-arabino-hexitol, 2-deoxy-D-lyxo-hexitol, and 2-deoxy-D-erythro-pentitol yielded a 1,3-monoacetal as a kinetic product in each reaction. The thermodynamic products were 4,6-monoacetals from 2-deoxy-D-arabino-hexitol and 2-deoxy-D-lyxo-hexitol, and a 3,5-monoacetal from 2-deoxy-D-erythro-pentitol 2-Deoxy-D-lyxo-hexitol also yielded diastereoisomeric 4,5-monoacetals.