Psychomotor Behavior: A Practical Approach in Drosophila

A Simple and Fast Battery Test for Phenotypic Characterization of Mice

Despite the great number of test batteries already known to assess the behavior of genetically modified and inbred strains of mice, only a few of them focus on basic neurological parameters. The purpose of the battery test proposed is to settle a specific methodology to characterize the phenotype of neurological disease models in mutant or genetically modified mice. This methodology is simple and efficient in order to analyze several parameters, including general activity, sensory nervous system, sensorimotor system, central nervous system and autonomous nervous system. This can aid the choice of specific additional tests as well as the determination of an interrelationship among phenotypic alterations observed. Although being efficient for a first analysis of a mouse model, interpretation of the results must be carefully made because phenotype manifestation may vary due to many parameters, including mouse strain, environmental and housing condition, animal-experimenter interaction, sample size and tests order. It is important to consider as a critical point if handling procedures are aversive. The results acquired with the analysis of 18 parameters together provide preliminary data to characterize mouse phenotype and helps selecting more specific tests.

Mutations in the Drosophila homolog of human PLA2G6 give rise to age-dependent loss of psychomotor activity and neurodegeneration

Infantile neuroaxonal dystrophy (INAD) is a fatal neurodegenerative disorder that typically begins within the first few years of life and leads to progressive impairment of movement and cognition. Several years ago, it was shown that >80% of patients with INAD have mutations in the phospholipase gene, PLA2G6. Interestingly, mutations in PLA2G6 are also causative in two other related neurodegenerative diseases, atypical neuroaxonal dystrophy and Dystonia-parkinsonism. While all three disorders give rise to similar defects in movement and cognition, some defects are unique to a specific disorder. At present, the cellular mechanisms underlying PLA2G6-associated neuropathology are poorly understood and there is no cure or treatment that can delay disease progression. Here, we show that loss of iPLA2-VIA, the Drosophila homolog of PLA2G6, gives rise to age-dependent defects in climbing and spontaneous locomotion. Moreover, using a newly developed assay, we show that iPLA2-VIA mutants also display impairments in fine-tune motor movements, motor coordination and psychomotor learning, which are distinct features of PLA2G6-associated disease in humans. Finally, we show that iPLA2-VIA mutants exhibit increased sensitivity to oxidative stress, progressive neurodegeneration and a severely reduced lifespan. Altogether, these data demonstrate that Drosophila iPLA2-VIA mutants provide a useful model to study human PLA2G6-associated neurodegeneration.