Biology subjects

Marin, F.

Publications and source records attributed to Marin, F..

3 recordsLinked to original sources

bioRxiv2022

Improved biodiversity detection using a large-volume environmental DNA sampler with in situ filtration and implications for marine eDNA sampling strategies

Metabarcoding analysis of environmental DNA samples is a promising new tool for marine biodiversity and conservation. Typically, seawater samples are obtained using Niskin bottles and filtered to collect eDNA. However, standard sample volumes are small relative to the scale of the environment, conventional collection strategies are limited, and the filtration process is time consuming. To overcome these limitations, we developed a new large - volume eDNA sampler with in situ filtration, capable of taking up to 12 samples per deployment. We conducted three deployments of our sampler on the robotic vehicle Mesobot in the Flower Garden Banks National Marine Sanctuary in the northwestern Gulf of Mexico and collected samples from 20 to 400 m depth. We compared the large volume ([~]40 - 60 liters) samples collected by Mesobot with small volume ([~]2 liters) samples collected using the conventional CTD - mounted Niskin bottle approach. We sequenced the V9 region of 18S rRNA, which detects a broad range of invertebrate taxa, and found that while both methods detected biodiversity changes associated with depth, our large volume samples detected approximately 66% more taxa than the CTD small volume samples. We found that the fraction of the eDNA signal originating from metazoans relative to the total eDNA signal decreased with sampling depth, indicating that larger volume samples may be especially important for detecting metazoans in mesopelagic and deep ocean environments. We also noted substantial variability in biological replicates from both the large volume Mesobot and small volume CTD sample sets. Both of the sample sets also identified taxa that the other did not - although the number of unique taxa associated with the Mesobot samples was almost four times larger than those from the CTD samples. Large volume eDNA sampling with in situ filtration, particularly when coupled with robotic platforms, has great potential for marine biodiversity surveys, and we discuss practical methodological and sampling considerations for future applications.

ecology↗

bioRxiv2021

Personalizing the control law of an upper-limb exoskeleton using EMG signal

Implementing an intuitive control law for an upper-limb exoskeleton dedicated to force augmentation is a challenging issue in the field of human-robot collaboration. The goal of this study is to adapt an EMG-based control system to a user based on individual caracteristics. To this aim, a method has been designed to tune the parameters of control using objective criteria, improving users feedback. The users response time is used as an objective value to adapt the gain of the controller. The proposed approach was tested on 10 participants during a lifting task. Two different conditions have been used to control the exoskeleton: with a generic gain and with a personalized gain. EMG signals was captured on five muscles to evaluate the efficiency of the conditions and the users adaptation. Results showed a statistically significant reduction of mean muscle activity of the deltoid between the beginning and the end of each situation (28.6 {+/-} 13.5% to 17.2 {+/-} 7.3% of Relative Maximal Contraction for the generic gain and from 24.9 {+/-} 8.5% to 18.0 {+/-} 6.8% of Relative Maximal Contraction for the personalized gain). When focusing on the first assisted movements, the personalized gain induced a mean activity of the deltoid significantly lower (29.0 {+/-} 8.0% of Relative Maximal Contraction and 37.4 {+/-} 9.5% of Relative Maximal Contraction, respectively). Subjective evaluation showed that the system with a personalized gain was perceived as more intuitive, and required less concentration when compared to the system with a generic gain.

bioengineering↗

bioRxiv2020

Acidic monosaccharides become incorporated into calcite single crystals

Carbohydrates, along with proteins and peptides, are known to represent a major class of biomacromolecules involved in calcium carbonate biomineralization. However, in spite of multiple physical or biochemical characterizations, the explicit role of saccharide macromolecules (long chains of carbohydrate molecules) is not yet understood in mineral deposition. In the present study we investigated the influence of two common acidic monosaccharides (MSs), which are the simplest form of carbohydrates and are represented here by glucuronic and galacturonic acids, on the formation of calcite crystals in vitro. We show that the size, morphology and microstructure of calcite crystals are altered when they are grown in the presence of these MSs. More importantly, MSs were found to become incorporated into the calcite crystalline lattice and induce anisotropic lattice distortions, a widely studied phenomenon in other biomolecules related to CaCO3 biomineralization but never before reported in the case of single MSs. Changes in the calcite lattice induced by MS incorporation were precisely determined by the technique of high-resolution synchrotron powder X-ray diffraction. We believe that the results of this research may deepen our understanding of the interaction of saccharide polymers with an inorganic host and shed light on the implications of carbohydrates for biomineralization processes.

bioengineering↗