Serotonin and forskolin enhance both magnitude of contraction and relaxation rate of Aplysia dorsal extrinsic muscle independently of acetylcholine receptor.

Hexamethonium bromide (Hex. Br.) blocks acetylcholine (ACh) elicited contractions but not electrically elicited contractions of isolated preparations of Aplysia californica dorsal extrinsic muscle.

Neuropeptide activation of an identifiable buccal ganglion motoneuron in Aplysia.

Application of the neuropeptide egg-laying hormone (ELH) of Aplysia to buccal ganglia activates a cell which has an axon in buccal nerve B4(17). The ELH-activated axon innervates buccal mass muscle 15(12). Criteria to identify and to record intracellularly from the ELH-activated neuron prior to ELH application were developed, and properties of the intracellularly recorded response were observed.

Forskolin activation of an identified peptide-sensitive motoneurone in Aplysia.

Activation of a physiological response by the adenylate cyclase activator, forskolin, has been suggested as a new criterion for testing the role of cyclic AMP. In Aplysia, motoneurone B16, which innervates muscle 15, is activated by the peptide egg-laying hormone (ELH). In high magnesium-low calcium medium, used to block synaptic activity, forskolin produced a similar response to ELH.

Serotonin-activated adenylate cyclase and the possible role of cyclic AMP in modulation of buccal muscle contraction in Aplysia.

The possible role of cyclic AMP in mediating opposite modulatory effects of serotonin (5-HT) on Aplysia buccal mass muscles E1 and E2 was examined. Serotonin enhances E1 contractions and inhibits E2 contractions. Adenylate cyclase in membranes of both E1 and E2 is stimulated approximately 180% by 10(-6) M 5-HT and 300% by 10(-3) M 5-HT.

Early onset of presbyopia.

Of the 800 presbyopes studied, 286 (35.75%) entered presbyopia at or before the age of 38 years. About 63% of these patients lived in rural areas and 37% in urban areas.

Serotonin has both excitatory and inhibitory modulatory effects on feeding muscles in Aplysia.

Serotonin (10(-8) M) produced opposite long-lasting (up to 10 min) effects on acetylcholine-elicited contractions of different buccal mass muscles of Aplysia. Contractions of the dorsal extrinsic muscle and accessory radula closer muscle were enhanced by serotonin; whereas contractions of the ventral extrinsic muscle were inhibited by serotonin. The effect of higher concentrations of serotonin on dorsal and ventral extrinsic muscles was in the same direction as at 10(-8) M but was greater in both magnitude and duration.

The nucleotide sequence surrounding the replication terminus of R6K.

The replication terminus of the plasmid R6K has been cloned into the single-stranded DNA phage vector M13mp5 and also into the plasmid vectors pBR313 and PBR322. By using single-stranded DNA templates prepared from the recombinant DNA clones, the sequence of 215 base pairs of DNA containing the replication terminus has been determined. The DNA sequence of the region of the terminus does not contain any 2-fold rotational symmetry.

Host dependence of RP1-specified resistance to ampicillin: differential expression in Escherichia coli and Rhizobium leguminosarum.

Rhizobium leguminosarum L4 is able to serve as a host for the plasmid RP1. Properties of R. leguminosarum [RP1] plasmid carrier suggest that the expression of RP1-coded Apr gene(s) is inhibited in this host, although the determinants of transfer and resistance to kanamycin and tetracycline are expressed.

Hormonal control of reproduction in Busycon: laying of egg capsules caused by nervous system extracts.

Mature specimens of female Busycon laid egg capsules when injected with extracts of nervous systems of male or female Busycon. The substance causing this behavior, named egg capsule laying substance (ECLS), was found most reliably in parietal ganglia, less consistently in cerebral-pleural ganglia, and rarely in other ganglia. Both species of Busycon found in Woods Hole, B.

Spectrophotometric determination of molybdenum by extraction of its thiosulphate complex.

A simple and rapid spectrophotometric determination of molybdenum is described. The molybdenum thiosulphate complex is extracted into isoamyl alcohol from 1.0-1.

Extractive separation of molybdenum as Mo(V) xanthate from Iron, vanadium, Tungsten, copper, uranium and other elements.

A simple and selective extraction of molybdenum is described. Tungsten is masked with tartaric acid and molybdenum(VI) is reduced in 2M hydrochloric acid by boiling with hydrazine sulphate. Iron, copper and vanadium are then masked with ascorbic acid, thiourea and potassium hydrogen fluoride respectively.

Spectrophotometric determination of molybdenum by extraction of a green molybdenum(v) species.

A simple method is described for the rapid spectrophotometric determination of molybdenum in samples containing 1-60% Mo, with satisfactory accuracy. Molybdenum is reduced with excess of hydrazine sulphate in boiling 5.5M hydrochloric acid and extracted with isoamyl acetate from 7M hydrochloric acid.

Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue.

A simple method is described for the separation of molybdenum from titanium, zirconium, chromium, manganese, iron, cobalt, nickel, uranium and aluminium in a wide variety of samples in <30 min. Phosphomolybdenum blue is produced by boiling for 2 min a molybdate solution containing phosphate to give Mo/P = 20-37 (w/w) with hydrazine sulphate in 0.1N sulphuric acid.