Croissance et capacité reproductive d’Hypnea musciformis (Rhodophyceae, Gigartinale) de la côte atlantique marocaine

Les algues carraghénophytes constituent une biomasse importante sur le littoral marocain et sont exportées à l’état brut sans transformation locale, alors que l’industrie de l’agar est très développée au Maroc. Le but de notre travail est la valorisation des espèces les plus abondantes en vue de leur transformation locale. Hypnea musciformis est l’une des espèces étudiées au laboratoire et constitue une candidate potentielle à l’exploitation. Sa valorisation passe par l’étude de sa biologie en milieu naturel, puis en conditions contrôlées. Les variations saisonnières de la croissance et de la capacité reproductive de l’algue rouge Hypnea musciformis ont été suivies durant deux années dans deux localités différentes au niveau de la côte atlantique marocaine. L’étude a permis de montrer que l’espèce est fertile toute l’année avec une large dominance de la génération tétrasporophytique, et présente deux périodes actives de croissance ; la première estivale et la seconde de moindre importance, automnale. Ainsi, le cycle biologique de l’algue se trouve influencé par plusieurs facteurs environnementaux tels que la lumière, la température, la salinité, la position de l’espèce au niveau de l’estran et les réponses d’acclimatation de l’algue aux différents types d’habitats.Mots-clés : Hypnea musciformis, croissance, reproduction, analyse statistiqu

Variabilité interspécifique de trois algues rouges : Hypnea musciformis, Gracilaria multipartita et Gelidium sesquipedalen(Rhodophycées) de la côte atlantique marocaine

Interspecific variability of the red algae: Hypnea musciformis, Gracilaria multipartita and Gelidium sesquipedale (Rhodophyceae) of the Moroccan atlantic coastTotal analysis of the growth of three red algae species; Hypnea  musciformis, Gracilaria multipartita and Gelidium sesquipedale were undertaken with an aim of determining interspecific variability within the same natural environment. The studied site is the beach of Mehdia located at the north of the Moroccan Atlantic coast. The results show specific differences in the growth rates of the three studied species. Gracilaria multipartita presents a significant development of the growth parameters like the size, the weight and the total ramification, especially for the aestival period compared to Gelidium sesquipedale and Hypnea musciformis. The active growth periods of Gracilaria multipartita are characterized by slightly important temperatures and light intensities and by high percentages of nitrates and phosphates. On the other hand, the growth of Hypnea musciformis shows fluctuations due to the variations of the environmental factors. The growth of Gelidium sesquipedale is slow and seems more under the influence of intrinsic factors than environmental factors

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Contains reports on four research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GK-835)National Institutes of Health (Grant 2 PO1 MH-04737-06)National Aeronautics and Space Administration (Grant NsG-496

Analyse structurale des fractions polysaccharidiques extraites de laparoi cellulaire d’Hypnea musciformis (Rhodophyceae, Gigartinales)

Structural analyze of polysaccharidic fractions extracted from the cellular wall of Hypnea musciformis (Rhodophyceae, Gigartinales)In Morocco, the industry of carrageenans (gelling and thickening) polysaccharides is not yet developed and the activity is reduced to the harvest and to the export in the raw state of some species of Gigartinaceae. Polysaccharides fractions of the cell wall of the carrageenophyte Hypnea  musciformis extracted according to their degree of solubility in water at various temperatures and increasing of ethanol concentration were analyzed quantitatively and qualitatively. Both methods of extraction show the homogeneity of the polymers extracted. The chemical composition of the phycocolloïds does not show important variations as regards the galactose and 3.6 anhydrogalactose which are the main constituents of the polysaccharide chain. Besides, sulfates are bound (connected) to the light fractions of carrageenans extracted according to the temperature and do not appear simultaneously during their synthesis according to the extraction to the ethanol. The IR and RMN of 13C spectroscopic analysis showed that the fractions extracted at different temperatures and concentrations of ethanol have de same structure. The carrageenans extracted from the wall of Hypnea musciformis is  omogenize of kappa type

Gene Expression Rhythms in the Mussel Mytilus galloprovincialis (Lam.) across an Annual Cycle

Seasonal environmental changes may affect the physiology of Mytilus galloprovincialis (Lam.), an intertidal filter-feeder bivalve occurring commonly in Mediterranean and Atlantic coastal areas. We investigated seasonal variations in relative transcript abundance of the digestive gland and the mantle (gonads) of males and females. To identify gene expression trends – in terms of relative mRNA abundance- we used a medium-density cDNA microarray (1.7 K probes) in dual-color competitive hybridization analyses. Hierarchical clustering of digestive gland microarray data showed two main branches, distinguishing profiles associated with the “hot” months (May–August) from the other months. Genes involved in chitin metabolism, associated with mussel nutrition and digestion showed higher mRNA levels during summer. Moreover, we found different gene transcriptomic patterns in the digestive glands of males when compared to females, during the four stages of mussel gonadal development. Microarray data from gonadal transcripts also displayed clear patterns during the different developmental phases respect to the resting period (stage I) with peak relative mRNA abundance at the ripe phase (stage III) for both sexes. These data showed a clear temporal pattern in transcriptomic profiles of mussels sampled over an annual cycle. Physiological response to thermal variation, food availability, and reproductive status across months may contribute to variation in relative mRNA abundance

Challenges of continuum robots in clinical context: a review

With the maturity of surgical robotic systems based on traditional rigid-link principles, the rate of progress slowed as limits of size and controllable degrees of freedom were reached. Continuum robots came with the potential to deliver a step change in the next generation of medical devices, by providing better access, safer interactions and making new procedures possible. Over the last few years, several continuum robotic systems have been launched commercially and have been increasingly adopted in hospitals. Despite the clear progress achieved, continuum robots still suffer from design complexity hindering their dexterity and scalability. Recent advances in actuation methods have looked to address this issue, offering alternatives to commonly employed approaches. Additionally, continuum structures introduce significant complexity in modelling, sensing, control and fabrication; topics which are of particular focus in the robotics community. It is, therefore, the aim of the presented work to highlight the pertinent areas of active research and to discuss the challenges to be addressed before the potential of continuum robots as medical devices may be fully realised

Etude des polysaccharides extraits de quelques algues rouges récoltées le long de la côte atlantique marocaine

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VP429 Impaired skeletal muscle strength in adult patients with laminopathies

Muscle is one of the most frequently affected tissues in laminopathies with loss of strength with or without joint contractures. Impairments in range of motion, grip strength and walking endurance have recently been measured in Hutchinson-Gilford progeria syndrome (Malloy et al. 2023). Here, we quantify muscle strength, joint contractures and walking in adult laminopathies (LGMD1B, EDMD, isolated dilated cardiomyopathy (DCM-CD) or partial lipodystrophy (PLD)). Handgrip and elbow/knee flexion/extension maximum isometric strength was measured by specific dynamometers. Strength and distance covered during a 6-minute walk test (6MWD) were expressed as a percentage of predicted value (%pred). The median(min,max) of the %pred values are presented here. So far, 30 participants aged 53(24,76) years, 20% male, have been included. Most had an impaired elbow flexion strength with a median below 100%pred regardless of phenotype: 17(6,44) for EDMD (n=3), 19(2,90) for myopathy+PLD (n=3), 51(16,65) for LGMD1B (n=9), 75(59,112) for PLD (n=9), 68 for Myopathy+DCM-CD (n=1) and 59(41,99) for DCM-CD (n=5). Elbow extension and flexion strengths were strongly correlated (rS=0.864,P<0.001), but not with elbow contracture. Handgrip strength was impaired in all participants with EDMD (61(58,62)) or myopathy+PLD (58(48,89)) and in some individuals with other phenotypes. The 6MWD was most affected in EDMD (45(0,78)), followed by myopathy+PLD (55(0,81)), LGMD1B (67(50,93)), PLD (87(66,101)), Myopathy+DCM-CD (92), and DCM-CD (98(69,103)). For all participants, knee extension and flexion strengths were strongly correlated (rS=0.730,P<0.001). The 6MWD was correlated with knee extension (rS=0.719,P<0.001) and flexion (rS=0.717,P<0.001) strength. At this stage of inclusion, no age dependence was observed for muscle strength or 6MWD. In conclusion, skeletal muscle weakness has been observed in the major phenotypes of laminopathies. Longitudinal follow-up is underway