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Duplicate genes emerge as copy-number variations (CNVs) at the population level, and remain copy-number polymorphic until they are fixed or lost. The successful establishment of such structural polymorphisms in the genome plays an important role in evolution by promoting genetic diversity, complexity and innovation. To characterize the early evolutionary stages of duplicate genes and their potential adaptive benefits, we combine comparative genomics with population genomics analyses to evaluate the distribution and impact of CNVs across natural populations of an eco-genomic model, the three-spined stickleback. With whole genome sequences of 66 individuals from populations inhabiting three distinct habitats, we find that CNVs generally occur at low frequencies and are often only found in one of the 11 populations surveyed. A subset of CNVs, however, displays copy-number differentiation between populations, showing elevated within-population frequencies consistent with local adaptation. By comparing teleost genomes to identify lineage-specific genes and duplications in sticklebacks, we highlight rampant gene content differences among individuals in which over 30% of young duplicate genes are CNVs. These CNV genes are evolving rapidly at the molecular level and are enriched with functional categories associated with environmental interactions, depicting the dynamic early copy-number polymorphic stage of genes during population differentiation.

Since the end of the Pleistocene, the three-spined stickleback (Gasterosteus aculeatus) has repeatedly colonized and adapted to various freshwater habitats probably originating from ancestral marine populations. Standing genetic variation and the underlying genomic architecture both have been speculated to contribute to recent adaptive radiations of sticklebacks. Here, we expand on the current genomic resources of this fish by providing extensive genome-wide variation data from six individuals from a marine (North Sea) stickleback population. Using next-generation sequencing and a combination of pairedend and mate-pair libraries, we detected a wide size range of genetic variation. Among the six individuals, we found more than 7% of the genome is polymorphic, consisting of 2 599 111 SNPs, 233 464 indels and structural variation (SV) (>50 bp) such as 1054 copynumber variable regions (deletions and duplications) and 48 inversions. Many of these polymorphisms affect gene and coding sequences. Based on SNP diversity, we determined outlier regions concordant with signatures expected under adaptive evolution. As some of these outliers overlap with pronounced regions of copy-number variation, we propose the consideration of such SV when analysing SNP data from re-sequencing approaches. We further discuss the value of this resource on genome-wide variation for further investigation upon the relative contribution of standing variation on the parallel evolution of sticklebacks and the importance of the genomic architecture in adaptive radiation.

Background Gene duplication is an important biological phenomenon associated with genomic redundancy, degeneration, specialization, innovation, and speciation. After duplication, both copies continue functioning when natural selection favors duplicated protein function or expression, or when mutations make them functionally distinct before one copy is silenced. Results Here we quantify the degree to which genetic parameters related to gene expression, molecular evolution, and gene structure in a diploid frog - Silurana tropicalis - influence the odds of functional persistence of orthologous duplicate genes in a closely related tetraploid species - Xenopus laevis. Using public databases and 454 pyrosequencing, we obtained genetic and expression data from S. tropicalis orthologs of 3,387 X. laevis paralogs and 4,746 X. laevis singletons - the most comprehensive dataset for African clawed frogs yet analyzed. Using logistic regression, we demonstrate that the most important predictors of the odds of duplicate gene persistence in the tetraploid species are the total gene expression level and evenness of expression across tissues and development in the diploid species. Slow protein evolution and information density (fewer exons, shorter introns) in the diploid are also positively correlated with duplicate gene persistence in the tetraploid. Conclusions Our findings suggest that a combination of factors contribute to duplicate gene persistence following whole genome duplication, but that the total expression level and evenness of expression across tissues and through development before duplication are most important. We speculate that these parameters are useful predictors of duplicate gene longevity after whole genome duplication in other taxa.

Spinal cord stimulation has been advocated as an alternative to motor cortex stimulation for motor tract activation. To test this theory, evoked responses were recorded from lumbar spinal cord (L2; n = 14), spinal roots (L4-L7; n = 112), peripheral nerves (sciatics; n = 28), and hind limb muscles (n

Resume Les auteurs rapportent un cas de “surdite corticale”: le patient etait dans l'incapacite totale d'identifier le langage oral, les bruits familiers et la musique, alors qu'il n'y avait pas d'alteration notable des seuils a l'audiometrie courante. Il y avait l'evidence, cliniques et radiologique, d'une lesion temporale gauche; une lesion plus ancienne situee sur les voies auditives controlaterales etait tres vraisemblable. Des epreuves psycho-acoustiques ont mis en evidence chez ce patient: une fragilite des stimulus sonores brefs, des difficultes a apprehender une suite prolongee de stimuli sonores (rythms), un default de localisation des sons, une augmentation de l'effet de masque homo- et heterolateral. Les seuils differentiels d'intensite et de frequence ainsi que les seuils de fusion semblaient en revanche peu atteints. Les potentiels evoques auditifs n'apparaissaient que pour des intensites tres superieures aux seuils audiometriques; contrairement aux seuils audiometriques, l'amplitude des potentiels evoques et tres fortement diminuee apres 9 mois d'evolution. La signification physiopathologique de chacun de ces resultats est brievement discutee.

A 75-year-old right-handed woman, after a probable cerebral infarct, developed an irregular constriction of the visual fields, a left-sided agraphia, and an anomia for objects in the left hand. Subsequent testing demonstrated an inability to name, though ability to recognize, letters and objects flashed in the homonymous left visual field. An inter-hemispheric disconnexion syndrome was inferred from these findings. The present publication concerns mainly the visual aspects of this disconnexion syndrome. Tasks were devised to test the abilities of the major and minor hemisphere: (a) the left hemisphere demonstrated a complete dominance for language expression and an incomplete dominance for written language comprehension; (b) the right hemisphere appeared to be dominant for some visuo-spatial tasks including number comprehension; (c) when the hemispheres were given contradictory visual informations on a non-verbal task (chimeric stimuli) there was a predominance of the right hemisphere. The right hemisphere appeared able to process complex information. Specialization of functional activities in each hemisphere is briefly discussed.

Six cases of Parinaud's syndrome, with downward (Cases 1, 2), upward (Cases 3, 4) and both downward and upward gaze paralysis (cases 5, 6) are reported. Four cases (Cases 1, 2, 3, 5) were studied anatomically using serial sections of the brain and 3 cases (Cases, 1, 4, 6) analysed electro-oculographically. In all the cases there were rather small vascular lesions in the mesodiencephalic region, sparing the oculomotor nuclei. Since the rostral interstitial nuclei of the medial longitudinal fasciculus (riMLF), located above the oculomotor nuclei, contain the final relays producing all vertical saccades, it is suggested that the different aspects of Parinaud's syndrome may result from damage to their cells or to their excitatory efferent tracts, or even to their afferent pathways. Downgaze paralysis results from bilateral lesions involving the regions located just caudal, medial and dorsal to the upper poles of the red nuclei. The critical area is probably related to the mediocaudal part of the riMLF, the lateral portion of which appears to be spared. These anatomical data, combined with the clinical observation that most downward eye movements (except slow reflex movements) are affected in the case with such paralysis, lead us to propose that it is the riMLF efferent tracts mediating downgaze and projecting on to the oculomotor nuclei that are principally damaged by the lesions. Upgaze paralysis results from unilateral lesions in or near the posterior commissure. The clinical data allow us to propose that it is also the riMLF efferent tracts, mediating upgaze, that are damaged in such cases. consequently these tracts, probably originating from the dorsolateral part of the riMLF, would decussate through the posterior commissure before they reach the oculomotor nuclei. Combined downgaze and upgaze paralysis results from bilateral lesions involving the region related to the whole riMLF on both sides. The principal conclusion is that the riMLF efferent tracts mediating upward and downward gaze have clearly separate courses in the immediate premotor structures.