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Membrane histochemistry of Physarum polycephalum myxamoebae
Abstract:
Myxamoebae of Physarum polycephalum are the uninucleate, haploid stage of the organism. Histochemical studies were undertaken to characterize intracellular and plasma membranes, and to provide a basis for assaying subcellular fractions for enrichment in plasma membranes. Lead salts deposition techniques were employed for hydrolytic enzymes. Alcian blue-ruthenium red, osmium tetroxide-potassium ferrocyanide, and phosphotungstic acid-chromic acid stains were evaluated for specificity for plasma membranes. Glucose 6-phosphatase was localized in endoplasmic reticulum, Golgi apparatus, and perinuclear space. 5'-Nucleotidase was localized in food vacuoles, chromatin, and plasmalemma. Acid phosphatase was in food vacuoles and Golgi apparatus. Alkaline phosphatase was in food vacuoles and endoplasmic reticulum. We conclude that none of the above enzymes is suitable as a cytochemical marker for plasma membranes of Physarum myxamoebae, but recommend instead staining ultrathin sections of membrane pellets with phosphotungstic acid-chromic acid, which stains plasma membranes selectively.
Insights
Researchers studied Physarum polycephalum myxamoebae membranes using histochemical stains. Phosphotungstic acid-chromic acid is recommended for selectively staining plasma membranes in these organisms.
Area of Science:
- Cell Biology
- Biochemistry
- Microbiology
Background:
- Myxamoebae are the haploid stage of Physarum polycephalum.
- Characterizing intracellular and plasma membranes is crucial for understanding cellular function.
- Establishing reliable methods for isolating and identifying plasma membranes is essential for biochemical analysis.
Purpose of the Study:
- To characterize intracellular and plasma membranes of Physarum polycephalum myxamoebae.
- To evaluate the specificity of various histochemical stains for plasma membranes.
- To identify suitable cytochemical markers for plasma membrane enrichment assays.
Main Methods:
- Histochemical studies utilizing lead salts deposition techniques for hydrolytic enzymes.
- Evaluation of Alcian blue-ruthenium red, osmium tetroxide-potassium ferrocyanide, and phosphotungstic acid-chromic acid stains.
- Localization of enzymes including Glucose 6-phosphatase, 5'-Nucleotidase, Acid phosphatase, and Alkaline phosphatase.
Main Results:
- Glucose 6-phosphatase was found in endoplasmic reticulum, Golgi apparatus, and perinuclear space.
- 5'-Nucleotidase localized to food vacuoles, chromatin, and plasmalemma.
- Acid and Alkaline phosphatases were detected in food vacuoles and endoplasmic reticulum, indicating none are specific plasma membrane markers.
Conclusions:
- None of the tested hydrolytic enzymes are suitable cytochemical markers for Physarum myxamoebae plasma membranes.
- Phosphotungstic acid-chromic acid staining of ultrathin sections of membrane pellets is recommended for selective plasma membrane visualization.
- This selective staining method provides a basis for future biochemical assays of plasma membrane-enriched subcellular fractions.