Postnatal training of 129/Sv mice confirms the long-term influence of early exercising on the motor properties of mice.

A previous study showed that motor experiences during critical periods of development durably affect the motor properties of adult C57BL/6J mice. However, dependence on early environmental features may vary with the genetic profile. To evaluate the contribution of the genetic background on external influences to motricity, we performed the same experiment in a 129/Sv mouse strain that show a strongly different motor profile.

The development of vestibular system and related functions in mammals: impact of gravity.

This chapter reviews the knowledge about the adaptation to Earth gravity during the development of mammals. The impact of early exposure to altered gravity is evaluated at the level of the functions related to the vestibular system, including postural control, homeostatic regulation, and spatial memory. The hypothesis of critical periods in the adaptation to gravity is discussed.

The long-term consequences of the exposure to increasing gravity levels on the muscular, vestibular and cognitive functions in adult mice.

Adult male mice C57Bl6/J were exposed to gravity levels between 1G and 4G during three weeks, and the long-term consequences on muscular, vestibular, emotional, and cognitive abilities were evaluated at the functional level to test the hypothesis of a continuum in the response to the increasing gravitational force. In agreement with the hypothesis, the growth of body mass slowed down in relation with the gravity level during the centrifugation, and weight recovery was inversely proportional. On the other hand, the long-term consequences on muscular, vestibular, emotional, and cognitive abilities did not fit the hypothesis of a continuum in the response to the gravity level.

Early postnatal motor experience shapes the motor properties of C57BL/6J adult mice.

This study aimed to evaluate the long-term consequences of early motor training on the muscle phenotype and motor output of middle-aged C57BL/6J mice. Neonatal mice were subjected to a variety of motor training procedures, for 3 weeks during the period of acquisition of locomotion. These procedures are widely used for motor training in adults; they include enriched environment, forced treadmill, chronic centrifugation, and hindlimb suspension.

Kinematics of treadmill locomotion in mice raised in hypergravity.

The study compared the motor performance of adult C57Bl/6J mice previously exposed to a 2G gravity environment during different periods of their development. 12 mice were housed in a large diameter centrifuge from the conception to Postnatal day 10 (P10). Another group of 10 mice was centrifuged form P10 to P30, and a third group of 9 mice was centrifuged from conception to P30.

Ontogeny of mouse vestibulo-ocular reflex following genetic or environmental alteration of gravity sensing.

The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system.

Behavioral and molecular exploration of the AR-CMT2A mouse model Lmna (R298C/R298C).

In 2002, we identified LMNA as the first gene responsible for an autosomal recessive axonal form of Charcot-Marie-Tooth disease, AR-CMT2A. All patients were found to be homozygous for the same mutation in the LMNA gene, p.Arg298Cys.

Exposure to hypergravity during specific developmental periods differentially affects metabolism and vestibular reactions in adult C57BL /6j mice.

The development of the posturo-motor control of movement is conditioned by Earth's gravity. Missing or altered gravity during the critical periods of development delays development and induces durable changes in the vestibular, cerebellar, or muscular structures, but these are not consistently mirrored at a functional level. The differences in the time schedule of vestibular and motor development could contribute to this inconstancy.

Stress response and humoral immune system alterations related to chronic hypergravity in mice.

Spaceflights are known to induce stress and immune dysregulation. Centrifugation, as hindlimb unloading, is a good ground based-model to simulate altered gravity which occurs during space missions. The aim of this study was to investigate the consequences of a long-term exposure to different levels of hypergravity on the stress response and the humoral immunity in a mouse model.

The adaptation of limb kinematics to increasing walking speeds in freely moving mice 129/Sv and C57BL/6.

The kinematics of locomotion was analyzed in two strains of great importance for the creation of mutated mice (C56BL/6 and 129/Sv). Different behavioral situations were used to trigger sequences of movement covering the whole range of velocities in the mice, and the variations of kinematic parameters were analyzed in relation with velocity. Both stride frequency and stride length contributed to the moving speed, but stride frequency was found to be the main contributor to the speed increase.

Detection of social approach in inbred mice.

An experiment was designed to automatically assess the relative level of social interaction during encounters involving trios of inbred mice consisting of two familiar cage mate males plus an unfamiliar third male. The automation of the spatial positioning was obtained by using a video-tracking program. In addition social behaviours were manually scored.

Impairment of novelty detection in mice targeted for the Chl1 gene.

A deficit in cell adhesion molecules including the human Chl1 (close homologue of the L1 cell adhesion molecule) gene may cause impairment of cognitive processes. Aberrant connectivity in the CA3 region of the hippocampus has been reported in mice lacking the CHL1 protein after Chl1 gene targeting. Previous studies have observed a deficit in the processing of novel information by CHL1-deficient mice.

Morphological, physiological and behavioural evaluation of a 'Mice in Space' housing system.

Environmental conditions likely affect physiology and behaviour of mice used for life sciences research on Earth or in Space. Here, we analysed the effects of cage confinement on the weightbearing musculoskeletal system, behaviour and stress of wild-type mice (C57BL/6JRj, 30 g b.wt.

Evidence of force exchanges during the six-legged walking of the bottom-dwelling fish, Chelidonichthys lucerna.

Locomotion in terrestrial vertebrates is supposed to be derived from preadaptation in bottom-dwelling fish. A few fish species have been assumed to walk on the substratum, on the basis of coordinated movements of their paired fins. However, the validity of this assumption has remained uncertain, because of a lack of evidence that their fin rays actually exert a force on the substratum.

Age-related changes in the motricity of the inbred mice strains 129/sv and C57BL/6j.

The development of motor skills was studied at different stages in the life of the mouse, focusing on three key aspects of motor development: early rhythmic motor activities prior to the acquisition of quadruped locomotion, motor skills in young adults, and the effect of aging on motor skills. The age-related development pattern was analysed and compared in two strains of major importance for genomic studies (C57Bl6/j and 129/sv). Early rhythmic air-stepping activities by l-dopa injected mice showed similar overall development in both strains; differences were observed with greater beating frequency and less inter-limb coordination in 129/sv, suggesting that 129/sv had a different maturation process.

Observational learning in C57BL/6j mice.

The ability of mice to solve a complex task by observational learning was investigated with C57BL/6j mice. Four female demonstrators were trained to reliably perform a sequence that consisted in pushing a piece of food into a tube attached to the side of a puzzle box, and recovering it by opening a drawer in front of the box. They then performed this sequence in front of naive mice assigned to individual cubicles in a box with a wire mesh front arranged in a row facing the demonstrators.

Mouse models of cognitive disorders in trisomy 21: a review.

Trisomy 21 (TRS21) is the most frequent genetic cause of mental retardation. Although the presence of an extra copy of HSA21 is known to be at the origin of the syndrome, we do not know which 225 HSA21 genes have an effect on cognitive processes. Mouse models of TRS21 have been developed using syntenies between HSA21 and MMU16, MMU10 and MMU17.

Pre-weaning sensorial and motor development in mice transpolygenic for the critical region of trisomy 21.

Trisomy 21 occurs every 1/800 births and is the most frequent genetic cause of mental retardation. Children with trisomy 21 show delayed sensorial and motor development as well as cognitive disorders. We selected a mouse model of trisomy 21 (TRS21): transgenic mice carrying extra copies of a HSA21 region corresponding to the D21S17-ETS2 region (previously referred to as "Down syndrome critical region 1").

Attack behaviors in mice: from factorial structure to quantitative trait loci mapping.

The emergence or non-emergence of attack behavior results from interaction between the genotype and the conditions under which the mice are tested. Inbred mice of the same strain reared or housed under conditions do not react the same way; reactions also vary according to the place selected for testing and the different opponents. A factor analysis showed that the attack behavior in non-isolated males, tested in neutral area covaried with high testosterone and steroid sulfatase and low brain 5-hydroxytriptamine (5-HT), beta-endorphin and Adrenocorticotropic Hormone (ACTH) concentration, whereas, for isolated males tested in their own housing cage, it covaried with high testosterone activity and low brain 5-HT concentration.

Functional analysis of genes implicated in Down syndrome: 2. Laterality and corpus callosum size in mice transpolygenic for Down syndrome chromosomal region -1 (DCR-1).

The association between atypical laterality and mental retardation has been reported several times, particularly in Down syndrome (DS). We investigated common genetic correlates of these components of the syndrome, examining direction (number of right paw entries in the Collins test) and degree (absolute difference between the number of right paw entries and the number of left paw entries) in mice that had incorporated extra-contiguous HSA21 fragments covering DCR-1 (Down Chromosomal Region-1). As corpus callosum size is substantially reduced in DS, and as the structure has been suspected of playing a role in atypical laterality, we also measured the corpus callosum in these mice.

Functional analysis of genes implicated in Down syndrome: 1. Cognitive abilities in mice transpolygenic for Down Syndrome Chromosomal Region-1 (DCR-1).

Down syndrome occurs every 1/1000 births and is the most frequent genetic cause of mental retardation. The genetic substrate of Down syndrome, an extra chromosome 21, was discovered by Lejeune, half-a-century ago, and the chromosome has been fully sequenced, although the gene(s) implicated in the mental retardation observed with the syndrome are still unknown. Observations of patients with partial trisomy of the 21q22.

Mitochondrial DNA modifies cognition in interaction with the nuclear genome and age in mice.

Several lines of evidence indicate an association between mitochondrial DNA (mtDNA) and the functioning of the nervous system. As neuronal development and structure as well as axonal and synaptic activity involve mitochondrial genes, it is not surprising that most mtDNA diseases are associated with brain disorders. Only one study has suggested an association between mtDNA and cognition, however.