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Interstrain variation in amylase gene copy number and mRNA abundance in three mouse tissues
Abstract:
Amylase expression in strain YBR differs in several respects from the standard mouse phenotype. The synthesis of salivary amylase is elevated twofold in YBR mice and the synthesis of pancreatic amylase is reduced to one-half the normal rate. We have compared the concentrations of amylase mRNA in the parotid, liver and pancreas of YBR mice with those in strains A/J and C3H. We observed differences in amylase mRNA abundance which can account for the levels of amylase protein synthesis in the parotid and pancreas of these strains. Unexpectedly, the concentration of amylase mRNA in the liver of YBR mice was also higher than in the other strains. Since liver amylase is transcribed from the same gene as parotid amylase, duplication of the Amy-1 locus could account for the elevated mRNA concentration in both tissues. Quantitative analysis of genomic DNA by Southern blotting provided direct evidence for duplication of Amy-1 in strain YBR.
Insights
Strain YBR mice exhibit altered amylase production, with higher salivary amylase and lower pancreatic amylase. Gene duplication of Amy-1 in YBR mice explains these amylase expression differences.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Amylase expression and synthesis vary between mouse strains.
- Strain YBR displays a unique phenotype with altered salivary and pancreatic amylase levels compared to standard mice.
Purpose of the Study:
- To investigate the molecular basis for differential amylase expression in strain YBR mice.
- To compare amylase mRNA concentrations in parotid, liver, and pancreas tissues across different mouse strains.
Main Methods:
- Quantitative analysis of amylase mRNA abundance in parotid, liver, and pancreas.
- Southern blotting for quantitative analysis of genomic DNA.
Main Results:
- Strain YBR mice show twofold elevated salivary amylase synthesis and halved pancreatic amylase synthesis.
- Differences in amylase mRNA abundance correlate with protein synthesis levels in parotid and pancreas.
- Unexpectedly higher amylase mRNA concentration was observed in the liver of YBR mice.
- Direct evidence for duplication of the Amy-1 locus in strain YBR was found.
Conclusions:
- Amy-1 locus duplication in strain YBR mice accounts for elevated amylase mRNA in both parotid and liver tissues.
- This genetic alteration explains the observed differences in amylase protein synthesis in strain YBR.