Table II.

Similarities and differences in muscle atrophy and hypertrophy in insects and mammals. Future research will benefit from studies in both species because of their complementary advantages.

COMPARING ADAPTIVE PROPERTIES OF MUSCLES IN MAMMALS AND DROSOPHILA
SIMILARITIES	MAJOR DIFFERENCES
FIBER COMPOSITION DIFFERS IN MUSCLES WITH DISTINCT PHYSIOLOGICAL ROLES (CONTINUALLY ACTIVE OXIDATIVE VS. GLYCOLYTIC MUSCLES) DISTINCT MUSCLES DIFFER IN SENSITIVITY TO ATROPHIC/HISTOLYTIC STIMULI (i.e. STEROIDS) FoxOs CAUSE MUSCLE ATROPHY IN MAMMALS AND INHIBITS GROWTH OF LARVAL MUSCLES IN FLIES THE UPS PLAYS A ROLE IN MUSCLE ATROPHY IN MAMMALS AS WELL AS IN MUSCLE LOSS DURING INSECT METAMORPHOSIS	FIBER ATROPHY AND HYPERTROPHY OCCUR IN ADULT MAMMALS BUT MAINLY DURING DEVELOPMENT DROSOPHILA MUSCLE STEM CELLS HAVE NOT BEEN OBSERVED IN FLIES DROSOPHILA LACKS A MAJOR UBIQUITIN LIGASE IMPLICATED IN MYOFIBRILLAR TURNOVER (MURF1)
ADVANTAGES FOR STUDYING MUSCLE ATROPHY AND HYPERTROPHY
IN DROSOPHILA	IN MAMMALS
FLIES HAVE A SHORTER LIFE CYCLE THAN MICE FLIES ARE EASILY AMENABLE TO VARIOUS GENETIC MANIPULATIONS (e.g. GENOME-WIDE RNAi SCREENS) LARGE GROUPS OF FLIES CAN BE ANALYZED FOR A GIVEN INTERVENTION THE 50-FOLD GROWTH DURING LARVAL DEVELOPMENT IS VALUABLE FOR STUDIES OF MYOFIBRILLAR ASSEMBLY AND GROWTH MECHANISMS	RODENTS LOSE MUSCLE MASS SIMILARLY TO HUMANS DURING DIFFERENT KINDS OF ATROPHY MUSCLES ARE ACCESSIBLE FOR PHYSIOLOGICAL AND BIOCHEMICAL STUDY ENDOCRINE SIGNALS REGULATING ATROPHY HAVE BEEN CHARACTERIZED IN MAMMALS ENERGY METABOLISM AND PHYSIOLOGICAL REGULATION OF MUSCLE MASS ARE WELL-CHARACTERIZED