Ionic gradients within mantle-collar epithelial cells of the land snail Otala lactea

1979 ◽  
Vol 199 (1) ◽  
Author(s):  
T.C. Appleton ◽  
P.F. Newell ◽  
J. Machin
Keyword(s):  
Epithelial Cells ◽  
Land Snail ◽  
Otala Lactea

Protein synthesis in vitro by mantle tissue of the land snail Otala lactea: possible insulin-like peptide function

2000 ◽  
Vol 78 (9) ◽  
pp. 1527-1535 ◽  
Author(s):  
A M Abdraba ◽  
A SM Saleuddin
Keyword(s):  
Protein Synthesis ◽  
Cerebral Ganglion ◽  
Land Snail ◽  
Porcine Insulin ◽  
Land Snails ◽  
Size Exclusion ◽  
Cerebral Ganglia ◽  
Molecular Masses ◽  
Otala Lactea

Mantle-collar tissue from adult land snails Otala lactea continuously incorporated labelled amino acids over a 72-h period of incubation in modified culture medium. Acid-saline extract of cerebral ganglia stimulated protein synthesis by the mantle-collar tissue in vitro. This effect was dose-dependent, with the minimum and maximum doses at 0.5 and 2 cerebral ganglion equivalents, respectively. The protein synthesis-stimulating factor(s) from the cerebral ganglia appeared to be proteinaceous and hydrophobic in nature. The cerebral ganglion extract was fractionated by means of a size-exclusion HPLC column. The biological activity was induced by three fractions with estimated molecular masses of 0.82, 1.88, and 4.33 kilodaltons (kDa). Porcine insulin antiserum abolished the activity of the 4.33- and 1.88-kDa fractions but had no significant effect on the activity of the 0.82-kDa fraction. The results suggest the existence in the cerebral ganglia of more than one factor with protein synthesis-stimulating activity. One of these factors could be related to mammalian insulin. Porcine insulin, however, had no significant effect on protein synthesis by the mantle collar in vitro.

scholarly journals Pyruvate Kinase from the Land Snail Otala Lactea: Regulation by Reversible Phosphorylation During Estivation and Anoxia

1990 ◽  
Vol 154 (1) ◽  
pp. 321-337 ◽  
Author(s):  
ROSS E. WHITWAM ◽  
KENNETH B. STOREY
Keyword(s):  
Protein Kinase ◽  
Pyruvate Kinase ◽  
Time Course ◽  
Land Snail ◽  
Active Enzyme ◽  
Kinetic Properties ◽  
Reversible Phosphorylation ◽  
Enzyme Form ◽  
Otala Lactea ◽  
Activity State

Pyruvate kinase (PK) from tissues of the desert snail Otala lactea (Müller) undergoes a stable modification of its kinetic properties during estivation or in response to anoxia stress. In foot muscle and mantle, the kinetic changes induced by either state were virtually identical and were consistent with a less active enzyme form in estivation or anoxia: S0.5 PEP increased, and I50 values for Mg-ATP and L-alanine decreased, compared to the enzyme in control (aroused) snails. Estivation and anoxia also changed the properties of PK from hepatopancreas; some changes were consistent with a more active enzyme form (So.5 PEP decreased, I50 values for Mg-ATP and L-alanine increased) but the enzyme lost all sensitivity to the potent activator fructose-l,6-bisphosphate. A time course of changes in I50 Mg-ATP for foot PK and S0.5 PEP for hepatopancreas PK revealed that estivation-induced changes in enzyme properties occurred between 12 and 48 h after snails were deprived of access to food and water, whereas the reversal of these changes occurred within as little as lOmin in foot muscle after arousal was initiated. The molecular basis of the stable modification of PK kinetics appears to be reversible protein phoshorylation. The action of added cyclic-AMP-dependent protein kinase on foot or hepatopancreas PK from control (aroused) snails changed PK kinetic parameters to those characteristic of the enzyme form in estivating animals; the addition of stimulators of endogenous cyclic-GMPdependent protein kinase or protein kinase C had the same effect. Conversely, treatment with added phosphatases reconverted the properties of foot muscle PK from estivating snails to those characteristic of the control enzyme. The data suggest that reversible phosphorylation control over the activity state of regulatory enzymes of glycolysis is one mechanism contributing to the overall metabolic rate depression of the estivating state.

Depression of Aerobic Metabolism and Intracellular pH by Hypercapnia in Land Snails, Otala Lactea

1988 ◽  
Vol 138 (1) ◽  
pp. 289-299 ◽  
Author(s):  
M. CHRISTOPHER BARNHART ◽  
BRIAN R. McMAHON
Keyword(s):  
Oxygen Consumption ◽  
Intracellular Ph ◽  
Respiratory Acidosis ◽  
Land Snail ◽  
Land Snails ◽  
Whole Body ◽  
Extracellular Acidosis ◽  
Critical Po2 ◽  
Otala Lactea ◽  
La Jolla

The pulmonate land snail Otala lactea undergoes simultaneous hypercapnia, hypoxia, extracellular acidosis and metabolic depression during dormancy. We tested the effects of ambient hypercapnia and hypoxia on oxygen consumption (VO2) and on extracellular and intracellular pH of active (i.e. non-dormant) individuals. Active snails reduced VO2, by 50% within l h when exposed to 65mmHg (1 mmHg = 133.3Pa) ambient PCO2, and by 63% in 98mmHg. These levels of CO2 are within the range that occurs naturally in the lung and blood during dormancy. VO2 of hypercapnic snails remained below that of controls for the duration of exposure (up to 9 h) and returned to control levels within 1 h when CO2 was removed. Both pHe and whole-body pHi (measured using [14C]DMO) fell with increasing haemolymph PCO2 by approximately 0.7logPCO2 Critical (VO2- limiting) ambient PO2 of active snails was 90mmHg in the absence of CO2 and dropped to 50 mmHg when VO2 was reduced 45% by exposure to CO2. Estimated critical PO2 at the lower VO2 typical of dormancy is well below the typical lung PO2 of dormant Otala, suggesting that PO2 in the lung does not normally limit oxygen consumption during dormancy. These results support the hypothesis that hypercapnia or resulting respiratory acidosis depresses metabolic rate during dormancy, and argue against a limitation of VO2 by hypoxia. Note: Present address: Physiological Research Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.

Localization and immunological characterization of insulin-like peptide(s) in the land snail Otala lactea (Mollusca: Pulmonata)

2000 ◽  
Vol 78 (9) ◽  
pp. 1515-1526 ◽  
Author(s):  
A M Abdraba ◽  
A SM Saleuddin
Keyword(s):  
Digestive Tract ◽  
Ethanol Extract ◽  
Land Snail ◽  
Size Exclusion ◽  
Connective Tissue Layer ◽  
Cerebral Ganglia ◽  
Molecular Masses ◽  
Otala Lactea ◽  
Vitro Analysis

Insulin-like peptides were detected by means of immunological techniques in tissues of the land snail Otala lactea. Insulin-positive cells were detected in all the ganglia except the right parietal ganglion and visceral ganglion. In the digestive tract, insulin-positive cells were found in the muscle and connective tissue layer of the intestine. The amount of insulin-like peptide detected in acid-ethanol extract of brains and digestive tracts from active snails did not differ significantly from that in the corresponding tissues from estivating (dormant) ones. More insulin-like peptide was detected in hemolymph from active snails than in hemolymph from estivating ones. Brains from active snails released insulin-like peptide in vitro. Analysis of the cerebral ganglia or digestive tract extracts by size-exclusion chromatography and insulin RIA revealed more than one fraction with insulin immunoreactivity. Some of these fractions contained material with molecular masses close to those of mammalian insulin or its subunits. Further analysis of the extracts by reverse-phase chromatography also revealed more than one fraction with immunoreactivity. The immunoreactive material from the digestive tract was found to be less hydrophobic than insulin. Western blot analysis of the cerebral ganglia extract revealed more than one band with insulin immunoreactivity. Three of these bands had molecular masses very similar to those of vertebrate insulin, its subunits, and its precursor.

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