MUC Genes and Types of Mucins
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Questions and Answers

Alcian blue is an effective dye for demonstrating neutral mucins.

False

The dye-tissue complex formed by Alcian blue is soluble after staining.

False

Phenylhydrazine is used to differentiate between neutral mucins and acid mucins.

True

Sialomucins that contain O-acetyl groups are resistant to enzymatic breakdown.

<p>True</p> Signup and view all the answers

Connecting tissue mucins can exhibit positive results if oxidation is maintained for up to 48 hours.

<p>False</p> Signup and view all the answers

Alcian blue has low specificity for acid mucins and calcium salts.

<p>False</p> Signup and view all the answers

Heparin is found in the dermis of the skin.

<p>False</p> Signup and view all the answers

The staining intensity of a tissue component with Alcian blue increases when used at a lower pH.

<p>False</p> Signup and view all the answers

Keratan sulphate contains uronic acid.

<p>False</p> Signup and view all the answers

Alcian green 3BX stains tissues with a blue-green color.

<p>True</p> Signup and view all the answers

Heparan sulphate is found in connective tissue of the aorta.

<p>True</p> Signup and view all the answers

N-acetyl-D-glucosamine is a component of both heparin and heparan sulphate.

<p>True</p> Signup and view all the answers

The sulphate ester groups on heparin are primarily found at C2 of the glucosamine.

<p>False</p> Signup and view all the answers

Keratan sulphate is located in the cornea and intervertebral discs.

<p>True</p> Signup and view all the answers

Iduronic acid is present in both heparin and heparan sulphate.

<p>False</p> Signup and view all the answers

The presence of a sulpho-amino group differentiates heparin from heparan sulphate.

<p>True</p> Signup and view all the answers

MUC genes are located on five different chromosomes, with a majority clustered on chromosome 11.

<p>True</p> Signup and view all the answers

Chondroitin sulphate A is found in the dermis of the skin and contains D-galactosamine.

<p>False</p> Signup and view all the answers

Strongly sulphated mucins are usually PAS-positive under standard periodic oxidation.

<p>False</p> Signup and view all the answers

Mucins can be categorized into three groups: acidic, neutral, and basic.

<p>False</p> Signup and view all the answers

Fibroblasts, endothelial cells, and chondrocytes are all types of cells that produce strongly sulphated connective tissue mucins.

<p>True</p> Signup and view all the answers

Chondroitin sulphate C is sulphate-esterified at the C4 position on the galactosamine molecule.

<p>False</p> Signup and view all the answers

Weakly sulphated mucins play a significant role in the composition of connective tissue.

<p>False</p> Signup and view all the answers

Atypical sulphated mucins are recognized for their high reactivity at low pH values.

<p>False</p> Signup and view all the answers

Enzyme labile sialomucins are unaffected by sialidase enzyme.

<p>False</p> Signup and view all the answers

Enzyme resistant sialomucins are PAS-positive.

<p>False</p> Signup and view all the answers

Hyaluronic acid consists of N-acetyl-D-glucosamine and D-glucoronic acid.

<p>True</p> Signup and view all the answers

Sulphated sialomucins are commonly accepted as a distinct group.

<p>False</p> Signup and view all the answers

Enzyme labile sialomucins are found in bronchial submucus glands.

<p>True</p> Signup and view all the answers

Hyaluronic acid has no effect on the viscosity of synovial fluid.

<p>False</p> Signup and view all the answers

The masking O-acetyl group is found on the sialic acid molecule of enzyme resistant sialomucins.

<p>True</p> Signup and view all the answers

Sialidase digestion enhances the demonstration of weakly sulphated mucins.

<p>False</p> Signup and view all the answers

Hexamine silver technique was first introduced by Gomori in 1946.

<p>True</p> Signup and view all the answers

Alpha amylase is extracted from the liver of hogs.

<p>False</p> Signup and view all the answers

The hexamine-silver solution should be heated to 72°C before incubation.

<p>False</p> Signup and view all the answers

Beta amylase can digest both branched and straight-chained glycogen.

<p>False</p> Signup and view all the answers

Diastase contains both alpha and beta amylase.

<p>True</p> Signup and view all the answers

Hexamine silver technique results in a red compound when glycogen is oxidized.

<p>False</p> Signup and view all the answers

Mucins will not be stained when using any oxidant in the hexamine silver technique.

<p>False</p> Signup and view all the answers

Pectinase is listed as an enzyme used in glycogen demonstration.

<p>True</p> Signup and view all the answers

Study Notes

MUC Genes and Chromosomes

  • MUC genes are located on more than five different chromosomes, with a significant cluster on chromosome 11.

Types of Mucins

  • Mucins are classified into two main categories: acidic mucins and neutral mucins.

Acidic Mucins

  • Acidic mucins can be further divided into sulphated types and carboxylated types.

Strongly Sulphated Mucins

  • Strongly sulphated mucins include types found in connective tissue and epithelial cells.
  • They react at low pH and are usually PAS-negative under standard conditions.
  • Key cell types producing strongly sulphated mucins include fibroblasts, endothelial cells, osteocytes, chondrocytes, and mast cells.

Sub-types of Strongly Sulphated Mucins

  • Chondroitin Sulphate A: Present in cartilage; contains D-galactosamine and D-glucuronic acid.
  • Chondroitin Sulphate B: Found in aorta, heart valves, and skin; contains 1-iduronic acid.
  • Chondroitin Sulphate C: Similar to A but sulphated at the C6 position; found in cartilage, umbilical cord, and skin.
  • Heparin/Heparan Sulphate: Contains N-acetyl-D-glucosamine and D-glucuronic acid; found in mast cells (heparin) and in aorta/cardiac tissue (heparan).
  • Keratan Sulphate: Composed of sulphated N-acetyl-D-glucosamine and galactose; found in cornea and intervertebral discs.

Sialomucins

  • Two types exist: enzyme labile and enzyme resistant.
  • Enzyme Labile Sialomucins: Digestible by sialidase and found in various glands and goblet cells.
  • Enzyme Resistant Sialomucins: Resistant to denaturation; consist of N-acetyl-O-acetyl neuraminic acids.

Sulphated Sialomucins

  • Debate exists regarding their classification; similar reactions to weakly sulphated mucins.

Hyaluronic Acid

  • Commonly occurs in fibroblasts; contains N-acetyl-D-glucosamine and D-glucuronic acid.
  • Essential in synovial fluid, influencing its viscosity.

Hexamine Silver Technique

  • Developed by Gomori and modified by Grocott; involves oxidizing glycogen to form aldehydes that react with silver nitrate.
  • Important for visualizing mucins but requires careful attention to timing and conditions during the process.

Glycogen Demonstration Enzymes

  • Various enzymes such as alpha amylase, beta amylase, and diastase are utilized for glycogen digestion.
  • Alpha Amylase: Extracted from hog pancreas, capable of digesting both branched and straight chains.
  • Beta Amylase: From barley or sweet potato, only digests straight chains.
  • Diastase: Common and stable enzyme that contains both alpha and beta amylase.

Mucin Staining Techniques

  • Phenylhydrazine-PAS: Differentiates between neutral and acid mucins through selective reactivity.
  • Alcian Blue: Popular for demonstrating acid mucins; operates at pH 2.5 for high specificity and strong coloration.

Varying pH for Alcian Blue

  • The intensity of staining increases at optimal pH levels where the reacting groups are fully ionized.
  • Various forms of Alcian dyes (e.g., Alcian Green, Alcian Yellow) offer alternative staining options for different acid mucins.

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Description

Explore the fascinating world of MUC genes, which are spread across multiple chromosomes, primarily clustered on chromosome 11. This quiz also delves into the classification of mucins into acidic and neutral types, outlining their specific characteristics and functions.

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