Ascidian gastrulation and blebbing activity of isolated endoderm blastomeres.

Gastrulation is the first dynamic cell movement during embryogenesis. Endoderm and mesoderm cells are internalized into embryos during this process. Ascidian embryos provide a simple system for studying gastrulation in chordates.

Alkyldihydropyrones, new polyketides synthesized by a type III polyketide synthase from Streptomyces reveromyceticus.

Genome sequencing allows a rapid and efficient identification of novel catalysts that produce novel secondary metabolites. Here we describe the catalytic properties of dihydropyrone synthase A (DpyA), a novel type III polyketide synthase encoded in a linear plasmid of Streptomyces reveromyceticus. Heterologous expression of dpyA led to the accumulation of alkyldihydropyrones A (1), B (2), C (3) and D (4), which are novel dihydropyran compounds that exhibit weak cytotoxicity against the leukemia cell line HL-60.

Acupuncture modulates mechanical responses of smooth muscle produced by transmural nerve stimulation in gastric antrum of genetically hyperglycemic rats.

Effects of acupuncture treatment on mechanical responses produced by transmural nerve stimulation (TNS) and acetylcholine (ACh) were investigated in circular smooth muscle preparations isolated from the antrum of the stomach of genetically hyperglycemic rats. While control rats had blood glucose levels of about 140 mg/dl, this was approximately tripled in the genetically hyperglycemic rats, but only doubled in the acupuncture treated genetically hyperglycemic rats. Antrum smooth muscle produced phasic contractions spontaneously, with a similar frequency and amplitude in the three groups of rats.

Properties of acetylcholine-induced hyperpolarization in smooth muscle cells of the mouse mesenteric artery.

The properties of smooth muscle cell hyperpolarization produced by acetylcholine (ACh) were investigated in mesenteric arteries isolated from mice. The resting membrane potential of the smooth muscle cells was about -60 mV. When ACh (10 microM) was applied for 1 min, the membrane hyperpolarized with a peak amplitude of about 5 mV which was reached in about 1 min, following which the potential slowly reverted to the resting level over about 7 min following withdrawal of ACh from the superfusate (recovery component).

Hyperpolarization-induced dilatation of submucosal arterioles in the guinea-pig ileum.

1. The effects of inhibition of acetylcholine (ACh)-induced hyperpolarization on dilatation of submucosal arterioles were investigated in the guinea-pig ileum. 2.