Reproduction de Bagrus bajad (Fabricius, 1775, Bagridae) du Lac Albert, Bassin du Nil, République Démocratique du Congo (RDC)

Le Bagrus bajad figure parmi les espèces des poissons très pêchées dans les cours d’eau tropicaux d’Afrique dont les informations sur la reproduction sont rares. Quelques paramètres de reproduction de Bagrus bajad du Sud-ouest du Lac Albert ont été étudiés durant cette recherche. Les échantillons ont été collectés entre décembre 2019 et décembre 2020 au moyen des éperviers, des palangres et des filets maillants de maille standard (20,2, 25,4 et 30,5 mm). Au total, 520 spécimens dont 283 femelles et 237 males ont été étudiés. Les informations sur le sex-ratio, le stade de maturité sexuelle, le rapport gonadosomatique, le rapport hepathosomatique, la fécondité et le facteur de condition ont été analysés. L’étude a révélé l’égalité entre les mâles et les femelle parmi les individus, même si les femelles étaient supérieurs aux mâles (1: 0,84; p-value<0.05). Tous les poissons étudiés ont présenté tous les stades de maturité sexuelle (I, II, III, IV, et V). Les matures (III, IV et V) ont une plus grande proportion (III, IV et V) par rapport aux immatures (I et II). Les mâles ont une taille de première maturité sexuelle de 43.5 cm contre 44 cm pour les femelles. Les valeurs mensuelles des indices gonadosomatiques et celles des stades gonadiques macroscopiques prouvent que B. bajad a trois périodes de fraie au cours de l’année : (i) Janvier-Avril ; (ii) Juin-Août et (iii) Octobre-Novembre alternées par une période d’un mois de repos en mai, septembre et décembre. La fécondité absolue est de 525 à 34440 ovocytes mais n’est pas significativement corrélées avec la longueur totale (R2=0,002) et le poids (R2=0,12). Les connaissances de la présente étude constituent une base fondamentale pour assurer la surveillance des risques d’épuisement du stock potentiel cette espèce et orienteront les décideurs à développer des politiques et stratégies efficaces garantissant l’exploitation et la conservation rationnelle de cette espèce.   Bagrus bayad is one of the highly fished fish species in tropical African rivers for which information on reproduction is scarce. Some reproduction parameters of B. bayad from the southwest of Lake Albert were studied. The samples were collected between December 2019 and December 2020 using cast nets, longlines, and standard mesh gillnets (20.2, 25.4, and 30.5 mm). A total of 520 specimens including 283 females and 237 males were examined. Information on sex ratio, stage of sexual maturity, gonadosomatic ratio, hepatosomatic ratio, fecundity, and condition factor was analyzed. The study revealed equality between males and females among individuals, although females were superior to males (1:0.84; p-value<0.05). All fish investigated showed all stages of sexual maturity (I, II, III, IV, and V). The mature (III, IV and V) have a greater proportion (III, IV and V) compared to the immature (I and II). Males have a size at first sexual maturity of 43.5 cm against 44 cm for females. The monthly values of gonadosomatic indices and those of macroscopic gonad stages show that B. bajad has three spawning periods a year: (i) January-April; (ii) June-August and (iii) October-November, alternated by a one-month rest period in May, September, and December. Absolute fecundity varies between 525 and 34440 oocytes but is not significantly correlated with total length (R2=0.002) and weight (R2=0.12). Knowledge from this study constitutes a fundamental basis for ensuring the monitoring of the risks of depletion of the potential stock of this species and will guide decision-makers in developing effective policies and strategies guaranteeing rational exploitation and conservation of this species

Dynamic Information Flow Based on EEG and Diffusion MRI in Stroke: A Proof-of-Principle Study

In hemiparetic stroke, functional recovery of paretic limb may occur with the reorganization of neural networks in the brain. Neuroimaging techniques, such as magnetic resonance imaging (MRI), have a high spatial resolution which can be used to reveal anatomical changes in the brain following a stroke. However, low temporal resolution of MRI provides less insight of dynamic changes of brain activity. In contrast, electro-neurophysiological techniques, such as electroencephalography (EEG), have an excellent temporal resolution to measure such transient events, however are hindered by its low spatial resolution. This proof-of-principle study assessed a novel multimodal brain imaging technique namely Variational Bayesian Multimodal Encephalography (VBMEG), which aims to improve the spatial resolution of EEG for tracking the information flow inside the brain and its changes following a stroke. The limitations of EEG are complemented by constraints derived from anatomical MRI and diffusion weighted imaging (DWI). EEG data were acquired from individuals suffering from a stroke as well as able-bodied participants while electrical stimuli were delivered sequentially at their index finger in the left and right hand, respectively. The locations of active sources related to this stimulus were precisely identified, resulting in high Variance Accounted For (VAF above 80%). An accurate estimation of dynamic information flow between sources was achieved in this study, showing a high VAF (above 90%) in the cross-validation test. The estimated dynamic information flow was compared between chronic hemiparetic stroke and able-bodied individuals. The results demonstrate the feasibility of VBMEG method in revealing the changes of information flow in the brain after stroke. This study verified the VBMEG method as an advanced computational approach to track the dynamic information flow in the brain following a stroke. This may lead to the development of a quantitative tool for monitoring functional changes of the cortical neural networks after a unilateral brain injury and therefore facilitate the research into, and the practice of stroke rehabilitation

Distinct Origin of the Y and St Genome in Elymus Species: Evidence from the Analysis of a Large Sample of St Genome Species Using Two Nuclear Genes

Previous cytological and single copy nuclear genes data suggested the St and Y genome in the StY-genomic Elymus species originated from different donors: the St from a diploid species in Pseudoroegneria and the Y from an unknown diploid species, which are now extinct or undiscovered. However, ITS data suggested that the Y and St genome shared the same progenitor although rather few St genome species were studied. In a recent analysis of many samples of St genome species Pseudoroegneria spicata (Pursh) À. Löve suggested that one accession of P. spicata species was the most likely donor of the Y genome. The present study tested whether intraspecific variation during sampling could affect the outcome of analyses to determining the origin of Y genome in allotetraploid StY species. We also explored the evolutionary dynamics of these species.Two single copy nuclear genes, the second largest subunit of RNA polymerase II (RPB2) and the translation elongation factor G (EF-G) sequences from 58 accessions of Pseudoroegneria and Elymus species, together with those from Hordeum (H), Agropyron (P), Australopyrum (W), Lophopyrum (E(e)), Thinopyrum (E(a)), Thinopyrum (E(b)), and Dasypyrum (V) were analyzed using maximum parsimony, maximum likelihood and Bayesian methods. Sequence comparisons among all these genomes revealed that the St and Y genomes are relatively dissimilar. Extensive sequence variations have been detected not only between the sequences from St and Y genome, but also among the sequences from diploid St genome species. Phylogenetic analyses separated the Y sequences from the St sequences.Our results confirmed that St and Y genome in Elymus species have originated from different donors, and demonstrated that intraspecific variation does not affect the identification of genome origin in polyploids. Moreover, sequence data showed evidence to support the suggestion of the genome convergent evolution in allopolyploid StY genome species

Evolution of the brain tumour spheroid model: transcending current model limitations

Tumour recurrence and the high mortality and morbidity associated with malignant brain tumours may be attributed to the failure of current therapeutic modalities (surgery, radiation and chemotherapy) to control the invasion of malignant brain turnout cells into healthy brain tissue. Several in vitro and in vivo models have been developed and used to study brain tumour invasion and cell motility. Here, we review some of the traditional in vitro models of brain tumour invasion and the latest adaptations to the widely used spheroid model. Several research groups studying the mechanisms mediating brain tumour invasion have made important contributions to the field by improving in vitro models of tumour migration and invasion. Sharing these advances will hopefully accelerate experimental discovery and the development of novel anti-invasion brain tumour therapies

A prospective and double blind study on neurotopin in patients with ischemic stroke

C