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PubMed1990

Changes in membrane properties during in-vitro meiotic maturation of the limpet Patella vulgata.

Changes in the membrane properties of the oocyte of the mollusk, Patella vulgata, were analyzed following the induction of meiosis reinitiation by paleopedial ganglia extract or by the weak base ammonia. During maturation it was possible to distinguish between an early phase characterized by an initial hyperpolarization and a late phase consisting of a depolarization which triggers an action potential with a long-term overshoot (20 minutes) of the membrane potential. Major changes in individual ionic permeabilities were studied using both current and voltage clamp conditions. The depolarizing phase appears to depend on decreases in K+ membrane permeability. Finally we observed that the overshoot did not appear to be directly related to germinal vesicle breakdown (GVBD) since it was absent in Na-deprived artificial sea water and could be elicited in the presence of TEA bromide, which did not induce maturation. This last observation suggests that it may result from a change in specific K+ ion permeability due to the possible activation of stretch channels.

Action Potentials↗
PubMed1982

Furosemide, Patella vulgata beta-glucuronidase and drug analysis: conditions for enhancement of the TLC detection of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine.

We have investigated the action of five sources of beta-glucuronidase enzymes on the hydrolysis of glucuronides of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine. For all glucuronides tested, Patella vulgata beta-glucuronidase yielded the largest thin layer chromatographic (TLC) spots. For oxymorphone, P. vulgata was the only treatment to yield detectable TLC spots under test parameters. For these six drugs, TLC spot size and chromatographic quality were compared between control horses and horses pretreated with furosemide four hours earlier. Furosemide pretreatment produced a statistically significant increase in spot size and was found to enhance chromatogram quality. These findings support previous suggestions that P. vulgata is a superior drug-glucuronide hydrolyzing enzyme. They also support earlier reports that administration of furosemide at four hours pre-race is unlikely to result in significant interference with routine drug testing procedures.

Animals↗
PubMed1983

Restriction of developmental potential and trochoblast ciliation in Patella embryos.

At the 64-cell-stage embryos of Patella develop a prototroch consisting of four groups of four cilia-bearing cells. Ciliogenesis of isolated blastomeres and trochoblasts was studied, as well as the effect on it of cleavage arrest caused by cytochalasin B treatment. Isolation of blastomeres or trochoblast cells has no influence on ciliogenesis; neither has arrest of cleavage in whole embryos after the third cleavage. However, cleavage arrest before third cleavage completely prevents ciliogenesis. Thus, third cleavage is decisive for the expression of the developmental potential of the primary trochoblasts. Impairment of DNA synthesis by aphidicolin in the S-phase preceding third cleavage also prevents ciliogenesis. It is concluded that a determinant for ciliogenesis as well as certain nuclear factors must be segregated into the micromeres at third cleavage for ciliogenesis to occur in the prototroch cells.

Animals↗
PubMed1982

Morphine glucuronide hydrolysis: superiority of beta-glucuronidase from Patella vulgata.

beta-Glucuronidase from Patella vulgata, Helix aspersa, Helix pomatia, and bovine liver were evaluated for usefulness in routine hydrolysis of drug-glucuronic acid conjugates from equine urine samples. Factors affecting the reaction rate (enzyme concentration, ligand concentration, temperature, and pH) were optimized. A 3-h incubation at 65 degrees C with 5000 U of beta-glucuronidase from P. vulgata per milliliter of urine resulted in complete hydrolysis of all morphine glucuronide in the urine samples. Not only was the enzyme preparation from P. vulgata the most cost-effective beta-glucuronidase source studied, but also its thermal stability is such that it can be used at a temperature high enough to substantially shorten the incubation interval. Preliminary work on other drugs that form glucuronide conjugates indicates that this same procedure is similarly superior for use in their hydrolysis.

Animals↗