Swine cytosolic malic enzyme: cDNA cloning, sequencing, and localization

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• A significant genetic association exists between Swine Leukocyte Antigen (SLA) alleles and cytosolic malic enzyme activity in swine muscle.
• The precise nature of this association, specifically whether it involves close genetic linkage, requires investigation.

Purpose of the Study:

• To determine if the observed genetic association between SLA and malic enzyme activity is due to physical linkage.
• To characterize the swine cytosolic malic enzyme gene (ME1) and its transcripts.

Main Methods:

• Screening of a swine cDNA library and RT-PCR to isolate malic enzyme (ME1) gene fragments.
• Northern blot analysis to detect ME1 transcripts in various tissues.
• Restriction Fragment Length Polymorphism (RFLP) analysis in informative families.
• In situ hybridization to determine gene localization on swine chromosomes.

Main Results:

• Two swine malic enzyme transcripts (2.0 and 3.1 kb) were identified, suggesting alternative forms of the ME1 gene.
• ME1 transcripts showed high similarity to mammalian counterparts and were highly expressed in adrenal gland, muscle, liver, and peripheral nerves.
• ME1 gene segregated independently from the SLA region in informative families.
• In situ hybridization localized the ME1 gene to swine Chromosome 1p1.2.

Conclusions:

• The malic enzyme (ME1) gene is not physically linked to the Swine Leukocyte Antigen (SLA) region in pigs.
• The observed association between SLA and malic enzyme activity is not explained by close genetic linkage.
• The underlying mechanisms for the association between SLA and malic enzyme activity require further elucidation.