title: Gene expression, fiber type, and strength are similar between left and right legs in older adults.
abstract: Methodological issues relevant to studies using microarrays and reverse transcription-polymerase chain reaction (RT-PCR) in human aging have rarely been evaluated. Because aging may accentuate biological differences between muscles, we compared transcriptome expression patterns, targeted messenger RNA (mRNA) abundance, strength, and muscle fiber type in the right and left legs of older adults. Muscle biopsies were taken from each Vastus lateralis in eight older (71 +/- 2 years) men, and isometric strength was determined. Samples were analyzed using an Affymetrix gene array, ATPase histochemistry, and RT-PCR for mRNA species involved in metabolism, apoptosis, vascular growth, and antioxidant status. Microarray analysis found that 31 of 5499 genes (0.6%) were significantly different between legs (negative log of the p value [NLOGP] >/= 2.0, but fold < 1.5), with only one gene, jumonji domain containing 1C (JMJD1C), being significantly different by >/= 1.50-fold. None of the mRNA species, or muscle fiber type, size, or strength, was different between legs. These findings are important for the design and analysis of studies using muscle data in older adults.
authors.affiliation: McMaster University Medical Center, Pediatrics and Medicine, 1200 Main Street W, Hamilton, Ontario, Canada. tarnopol@mcmaster.ca
authors.forename: Mark
authors.initials: M
authors.lastname: Tarnopolsky
authors.forename: Stuart
authors.initials: S
authors.lastname: Phillips
authors.forename: Gianni
authors.initials: G
authors.lastname: Parise
authors.forename: Alex
authors.initials: A
authors.lastname: Varbanov
authors.forename: James
authors.initials: J
authors.lastname: Demuth
authors.forename: Paul
authors.initials: P
authors.lastname: Stevens
authors.forename: Angela
authors.initials: A
authors.lastname: Qu
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Robert
authors.initials: R
authors.lastname: Isfort
mesh_terms: D000367:Age Factors; D000368:Aged; D020869:Gene Expression Profiling; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases; D007866:Leg; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D010089:Oxidoreductases, N-Demethylating / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C520448:JMJD1C protein, human; D056484:Jumonji Domain-Containing Histone Demethylases; D010089:Oxidoreductases, N-Demethylating