The effect of stocking density on growth rate and maturation time in laboratory-reared california sea hares.

California sea hares (Aplysia californica) were reared from the late juvenile period (approximately day 100 posthatch) to senescence in a laboratory study of growth and maturation at different stocking densities. Temperature, light, and food were controlled, and other seawater parameters such as O2 concentration, pH, and salinity, although not controlled, were optimized by the flow-through design of seawater through the cages. Stocking densities evaluated were 1, 2, 5, 10, 15, and 20 animals per 16-liter cage.

The development of excitatory capability in Aplysia californica bag cells observed in cohorts.

The bag cells of Aplysia release egg laying hormone in sexually mature animals. Bag cells cannot sustain the long-lasting excitatory afterdischarge (AD) required for hormone release prior to sexual maturity (T.A.

Brevetoxin modulates neuronal sodium channels in two cell lines derived from rat brain.

Single Na+ channel currents were recorded from cell-attached membrane patches from two neuronal cell lines derived from rat brain, B50 and B104, and compared before and after exposure of the cells to purified brevetoxin, PbTx-3. B50 and B104 Na+ channels usually exhibited fast activation and inactivation as is typical of TTX-sensitive Na+ channels. PbTx-3 modified channel gating in both cell lines.

Ionic currents in normal and neurofibromatosis type 1-affected human Schwann cells: induction of tumor cell K current in normal Schwann cells by cyclic AMP.

Comparisons were made of whole cell voltage clamp recordings from cultures of normal Schwann cells (SC) from three human subjects and from three neurofibrosarcoma cell lines. The whole cell K+ (K) currents of normal and tumor cells could be divided into three types based on voltage activation range, pharmacology, and macroscopic inactivation: A type current, tetraethylammonium- (TEA-) only-sensitive current, and inward rectifier current. The most conspicuous difference between normal and tumor cells was the nature of K currents present.

Characterization of Na+ and Ca2+ currents in bag cells of sexually immature Aplysia californica.

The neurosecretory bag cells of sexually mature Aplysia californica release egg-laying hormones as part of the reproductive process after a train of action potentials termed afterdischarge. Whole-cell voltage-clamp experiments were performed in cultured cells from sexually immature A. californica to characterize the inward voltage-gated currents for Na+ and Ca2+.

Single K channel currents in Schwann cells from normal and neurofibromatosis-affected damselfish.

Damselfish neurofibromatosis is a naturally occurring disease of a tropical marine fish species. Affected fish exhibit peripheral nerve sheath tumors which contain morphologically abnormal Schwann cells (SC), similar to tumors encountered in the human disease neurofibromatosis type 1. Unitary A-type K channels in cell-attached membrane patches of SC were studied.

Characterization and modulation of Na+ and Ca2+ currents underlying the action potential in bag cells of two species of Aplysia.

The neurosecretory bag cells of Aplysia produce long trains of action potentials (afterdischarge) to release hormones important to egg laying. These ionic currents are modulated by second messengers. Modulation of excitability in bag cells is incompletely understood partly because the currents that are modulated have not been fully characterized.

Differences in a K current in Schwann cells from normal and neurofibromatosis-infected damselfish.

Patch clamp techniques were used to study whole cell ionic currents in Schwann cells (SC) from a tropical marine fish, the bicolor damselfish, Pomacentrus partitus. The bicolor damselfish is affected by a disease termed damselfish neurofibromatosis (DNF), being developed as an animal model of neurofibromatosis-type 1 (NF1) in humans. NF1 affects SC, fibroblasts, and perineurial cells.