Genetic structure and invasion history of the house mouse (Mus musculus domesticus) in Senegal, West Africa: a legacy of colonial and contemporary times.

Knowledge of the genetic make-up and demographic history of invasive populations is critical to understand invasion mechanisms. Commensal rodents are ideal models to study whether complex invasion histories are typical of introductions involving human activities. The house mouse Mus musculus domesticus is a major invasive synanthropic rodent originating from South-West Asia. It has been largely studied in Europe and on several remote islands, but the genetic structure and invasion history of this taxon have been little investigated in several continental areas, including West Africa. In this study, we focussed on invasive populations of M. m. domesticus in Senegal. In this focal area for European settlers, the distribution area and invasion spread of the house mouse is documented by decades of data on commensal rodent communities. Genetic variation at one mitochondrial locus and 16 nuclear microsatellite markers was analysed from individuals sampled in 36 sites distributed across the country. A combination of phylogeographic and population genetics methods showed that there was a single introduction event on the northern coast of Senegal, from an exogenous (probably West European) source, followed by a secondary introduction from northern Senegal into a coastal site further south. The geographic locations of these introduction sites were consistent with the colonial history of Senegal. Overall, the marked microsatellite genetic structure observed in Senegal, even between sites located close together, revealed a complex interplay of different demographic processes occurring during house mouse spatial expansion, including sequential founder effects and stratified dispersal due to human transport along major roads.

Permanent genetic resources added to Molecular Ecology Resources Database 1 October 2010-30 November 2010.

This article documents the addition of 277 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Ascochyta rabiei, Cambarellus chapalanus, Chionodraco hamatus, Coptis omeiensis, Cynoscion nebulosus, Daphnia magna, Gerbillus nigeriae, Isurus oxyrinchus, Lates calcarifer, Metacarcinus magister, Oplegnathus fasciatus, Pachycondyla verenae, Phaethon lepturus, Pimelodus grosskopfii, Rotylenchulus reniformis, Scomberomorus niphonius, Sepia esculenta, Terapon jarbua, Teratosphaeria cryptica and Thunnus obesus. These loci were cross-tested on the following species: Austropotamobius italicus, Cambarellus montezumae, Cambarellus puer, Cambarellus shufeldtii, Cambarellus texanus, Chionodraco myersi, Chionodraco rastrospinosus, Coptis chinensis, Coptis chinensis var. brevisepala, Coptis deltoidea, Coptis teeta, Orconectes virilis, Pacifastacus leniusculus, Pimelodus bochii, Procambarus clarkii, Pseudopimelodus bufonius, Rhamdia quelen, Sepia andreana, Sepiella maindroni, Thunnus alalunga, Thunnus albacares, Thunnus maccoyii, Thunnus orientalis, Thunnus thynnus and Thunnus tonggol.

Genetic structure and gene flow in French populations of two Ostrinia taxa: host races or sibling species?

Most models of ecological speciation concern phytophagous insects in which speciation is thought to be driven by host shifts and subsequent adaptations of populations. Despite the ever-increasing number of studies, the current evolutionary status of most models remains incompletely resolved, as estimates of gene flow between taxa remain extremely rare. We studied the population genetics of two taxa of the Ostrinia genus--one feeding mainly on maize and the other on mugwort and hop--occurring in sympatry throughout France. The actual level of divergence of these taxa was unknown because the genetic structure of populations had been investigated over a limited geographical area and the magnitude of gene flow between populations had not been estimated. We used 11 microsatellite markers to investigate the genetic structure of populations throughout France and the extent of gene flow between the two Ostrinia taxa at several sites at which they are sympatric. We observed clear genetic differentiation between most populations collected on the typical respective hosts of each taxon. However, populations displaying intermediate allelic frequencies were found on hop plants in southern France. Individual assignments revealed that this result could be accounted for by the presence of both taxa on the same host. Gene flow, estimated by determining the proportion of hybrids detected, was low: probably<1% per generation, regardless of site. This indicates that the two Ostrinia taxa have reached a high level of genetic divergence and should be considered sibling species rather than host races.

[Acute myelopathies in young patients and multiple sclerosis. prospective study of 20 cases]. / Myélopathies aiguës du sujet jeune et sclérose en plaques. Etude prospective de 20 cas.

The risk of progression to multiple sclerosis (MS) after an episode of acute non compressive episode involving the spinal cord remains uncertain. A follow-up study was performed to determine the risk of early progression to MS in 20 patients presenting with clinically isolated lesions of the spinal cord, combined clinical evaluation, spinal and brain magnetic resonance imaging (MRI), visual, brainstem auditory and somatosensory evoked potentials (VEPs, BAEPs, SEPs), and cerebrospinal fluid (CSF) electrophoresis analysis. Spinal cord MRI demonstrated more lesions in cervical region (74 p. 100) than thoracic or lumbar regions (26 p. 100). Six patients (30 p. 100) had an initial brain MRI that was strongly suggestive of MS and 5 patients (25 p. 100) had only one MS-like abnormality. Eight patients (40 p. 100) had abnormal VEPs, 3 (15 p. 100) abnormal BAEPSs and only 44 p. 100 (8/18) abnormal SEPs. In contrast, CSF analysis showed oligoclonal bands (CSFOB) in 15/19 patients (79 p. 100). The diagnosis of MS was performed initially in 13 cases (65 p. 100) (clinically definite MS (CDMS) in 30 p. 100, laboratory-supported definite MS (LSDMS) in 61 p. 100 and clinically probable (CPMS) in one case). During the follow-up period (18 +/- 7 months), 8 patients (40 p. 100) presented one or more exacerbations and time to the first recurrence was 8 +/- 5 months. Seven of these 8 patients were initially treated by infusion of methylprednisolone. Among these patients, all of them had CSF OB and initial brain MRI was strongly suggestive of MS in 3 of them. During this follow-up period, brain MRI showed emergence of lesions in 4 cases with normal initial examination and 3 of them presented exacerbations. At the follow-up term, the diagnosis of MS was performed in 15 cases (75 p. 100) CDMs in 66 p. 100, LSDMS in 26 p. 100 and CPMS in one case). This confirms the predictive value of brain MRI and CSF OB for the diagnosis of MS in patients who present with clinically isolated acute syndrome of the spinal cord.

[Reflex epilepsy with seizures induced by mental calculation, playing chess and scrabble]. / Epilepsie réflexe avec crises induites par le calcul mental, le jeu d'échecs et le jeu de scrabble.

Reflex seizures induced by higher mental activity is rare. We report the case of a young man with myoclonic jerks and generalized tonico-clonic convulsion precipitated by calculation, playing chess and scrabble. Routine EEG, including hyperventilation and photic stimulation, showed no abnormality. Tests stimulation procedures, including spatial tasks, induced focal and generalized EEG spike-wave complex and myoclonic jerks. Valproate was effective in reducing epileptic seizures during a follow-up period of three years. Comparison of our case with previously reported reflex epilepsy with seizures induced by higher mental activity is discussed.

[Spinal dural fistula with peri-medullar venous drainage]. / Les fistules durales rachidiennes à drainage veineux périmédullaire.

Clinical and neuroradiological findings of 8 patients with a spinal dural arteriovenous fistula are reviewed. Disturbance of micturition or defecation and weakness of the legs were always present and the most frequent initial symptom was a progressive spastic paraparesis. Duration of symptoms before diagnosis was 2 years. Lumbar puncture showed elevation of proteins and myelography demonstrated dilated perimedullar posterior veins. In every case, magnetic resonance imaging of the spinal cord (T2- weighted images) revealed intramedullary high signal intensity of the conus medullaris and selective angiography confirmed the site of the dural fistula. Each patient was treated with endovascular method consisting in liquid adhesive embolization (0.2 cc of N-butyl cyanoacrylate) with hyperselective catheterism of the dorsospinal artery. Embolization procedure was successful in 6 cases with large improvement of leg weakness and partial regression of disturbed micturition and defecation. The pathophysiological mechanisms explaining the clinical signs are discussed.

[Hemichorea-hemiballismus and toxoplasmosis in AIDS]. / Hémichorée-hémiballisme et toxoplasmose au cours du SIDA.

The authors report two cases of hemichorea-hemiballism revealing a toxoplasmic abscess in the subthalamic nucleus during AIDS. Despite the great frequency of this opportunistic infection such cases are exceptional. This rarity seems to be explained by the frequent association of other lesions of the basal ganglia which may prevent the movement disorders. Nevertheless an hemichorea-hemiballism in young people must suggest a cerebral toxoplasmosis. Finally a symptomatic treatment is often necessary; in these cases the use of sodium valproate must be considered, this drug being able to induce a clinical improvement.

[Paralytic pontine exotropia disclosing endocarditis]. / Exotropie pontique paralytique révélatrice d'une endocardite.

A case of bacterial endocarditis complicated by paralytic pontine exotropia is reported. Magnetic resonance imaging clearly showed a rostral lesion of the paramedial pontine reticular formation and the medial longitudinal fasciculus. The occurrence of paralytic pontine exotropia is suggestive of ischaemia, and patients with this so-called "one-and-a-half syndrome" associated with signs of infection should be investigated for endocarditis.