The Drivers of Low Vaccination Utilization in Niger.

Vaccination adherence involves the expected benefit of a vaccine and the perceived risk of the disease. To develop an evidence-based communication strategy aimed at improving vaccination coverage in Niger, we conducted a mixed socio-anthropological study of the perceptions among the population on the benefit and the risk of the childhood (Expanded Program on Immunization) and the COVID-19 vaccines. Our results show that negative rumors are not a significant driver of vaccine refusal. The insufficient level of fully vaccinated, compared with partially vaccinated, children might be explained by misunderstandings around the side effects of vaccines and the necessity for full vaccination. Approximately one-fourth of the population is vaccinated against COVID-19, whereas 73.3% think that vaccines against the disease are a "good thing," and 83% of those who have heard messages promoting the vaccination approve of them. This apparent contradiction is explained by a low perception of the risks of COVID-19. More than half of the population surveyed believe that the disease is not present in the country. A large majority believe that only ill people can transmit the disease, whereas only 12.8% think they know anybody who has ever been sick with COVID-19. Three-fourths of the interviewees have seen images from around the world of persons sick or deceased from COVID-19; the same proportion has not seen any such images of affected patients in Niger. Communication to improve COVID-19 uptake should focus on the reality of the disease presence and its transmission and not on rumors surrounding the vaccines.

Moderate intensity continuous versus high intensity interval training: Metabolic responses of slow and fast skeletal muscles in rat.

The healthy benefits of regular physical exercise are mainly mediated by the stimulation of oxidative and antioxidant capacities in skeletal muscle. Our understanding of the cellular and molecular responses involved in these processes remain often uncomplete particularly regarding muscle typology. The main aim of the present study was to compare the effects of two types of exercise training protocol: a moderate-intensity continuous training (MICT) and a high-intensity interval training (HIIT) on metabolic processes in two muscles with different typologies: soleus and extensor digitorum longus (EDL). Training effects in male Wistar rats were studied from whole organism level (maximal aerobic speed, morphometric and systemic parameters) to muscle level (transcripts, protein contents and enzymatic activities involved in antioxidant defences, aerobic and anaerobic metabolisms). Wistar rats were randomly divided into three groups: untrained (UNTR), n = 7; MICT, n = 8; and HIIT, n = 8. Rats of the MICT and HIIT groups ran five times a week for six weeks at moderate and high intensity, respectively. HIIT improved more than MICT the endurance performance (a trend to increased maximal aerobic speed, p = 0.07) and oxidative capacities in both muscles, as determined through protein and transcript assays (AMPK-PGC-1α signalling pathway, antioxidant defences, mitochondrial functioning and dynamics). Whatever the training protocol, the genes involved in these processes were largely more significantly upregulated in soleus (slow-twitch fibres) than in EDL (fast-twitch fibres). Solely on the basis of the transcript changes, we conclude that the training protocols tested here lead to specific muscular responses.

Targeting beta-catenin signaling for prevention of colorectal cancer - Nutraceutical, drug, and dietary options.

Progressive up-regulation of ß-catenin signaling is very common in the transformation of colorectal epithelium to colorectal cancer (CRC). Practical measures for opposing such signaling hence have potential for preventing or slowing such transformation. cAMP/PKA activity in colon epithelium, as stimulated by COX-2-generated prostaglandins and ß2-adrenergic signaling, boosts ß-catenin activity, whereas cGMP/PKG signaling has the opposite effect. Bacterial generation of short-chain fatty acids (as supported by unrefined high-carbohydrate diets, berberine, and probiotics), dietary calcium, daily aspirin, antioxidants opposing cox-2 induction, and nicotine avoidance, can suppress cAMP production in colonic epithelium, whereas cGMP can be boosted via linaclotides, PDE5 inhibitors such as sildenafil or icariin, and likely high-dose biotin. Selective activation of estrogen receptor-ß by soy isoflavones, support of adequate vitamin D receptor activity with UV exposure or supplemental vitamin D, and inhibition of CK2 activity with flavanols such as quercetin, can also oppose ß-catenin signaling in colorectal epithelium. Secondary bile acids, the colonic production of which can be diminished by low-fat diets and berberine, can up-regulate ß-catenin activity by down-regulating farnesoid X receptor expression. Stimulation of PI3K/Akt via insulin, IGF-I, TLR4, and EGFR receptors boosts ß-catenin levels via inhibition of glycogen synthase-3ß; plant-based diets can down-regulate insulin and IGF-I levels, exercise training and leanness can keep insulin low, anthocyanins and their key metabolite ferulic acid have potential for opposing TLR4 signaling, and silibinin is a direct antagonist for EGFR. Partially hydrolyzed phytate can oppose growth factor-mediated down-regulation of ß-catenin by inhibiting Akt activation. Multifactorial strategies for safely opposing ß-catenin signaling can be complemented with measures that diminish colonic mutagenesis and DNA hypomethylation - such as avoidance of heme-rich meat and charred or processed meats, consumption of phase II-inductive foods and nutraceuticals (e.g., Crucifera), and assurance of adequate folate status.

Properties of Cephalopod Skin Ommochromes to Inhibit Free Radicals, and the Maillard Reaction and Retino-Protective Mechanisms in Cellular Models Concerning Oxidative Stress, Angiogenesis, and Inflammation.

Ommochromes are pigments of invertebrates that exhibit oxidative stress protection. The aim of this study was to investigate ommochromes extracted from cephalopod's skin for their ability to inhibit age-related-macular degeneration (AMD)-related factors such as H2O2-induced and iron-dependent oxidative stress (ferroptosis and erastin), accumulation of advanced glycation end-products (AGEs), as well as vascular endothelial growth factor (VEGF), and inflammatory cytokines (interleukin 6 and interleukin 8) secretion. As cell systems, we used primary porcine retinal pigment epithelium (RPE), human retinal pigment epithelium cell line ARPE-19 and uveal melanoma cell line OMM-1. In vitro, ommochromes produced an antiglycation effect by the inhibition of fructosylation reaction. The ommochromes showed protective effects against erastin- induced cell death in ARPE-19. In addition, in long-term stimulation (7 days) ommochromes decreased constitutively secreted VEGF, as well as interleukin 6 and interleukin 8 induced by Poly I:C in primary RPE. No relevant effects were detected in OMM-1 cells. The effects are dependent on the cell system, time of exposition, and concentration. This substance is of interest for further research concerning age-related macular degeneration.

Inhibition of Pathogenic Bacteria and Fungi by Natural Phenoxazinone from Octopus Ommochrome Pigments.

Cephalopods, in particular octopus (Octopus vulgaris), have the ability to alter their appearance or body pattern by showing a wide range of camouflage by virtue of their chromatophores, which contain nanostructured granules of ommochrome pigments. Recently, the antioxidant and antimicrobial activities of ommochromes have become of great interest; therefore, in this study, the pH-dependent redox effect of the extraction solvent on the antioxidant potential and the structural characterization of the pigments were evaluated. Cell viability was determined by the microdilution method in broth by turbidity, MTT, resazurin, as well as fluorescence microscopy kit assays. A Live/Dead Double Staining Kit and an ROS Kit were used to elucidate the possible inhibitory mechanisms of ommochromes against bacterial and fungal strains. The results obtained revealed that the redox state alters the color changes of the ommochromes and is dependent on the pH in the extraction solvent. Natural phenoxazinone (ommochromes) is moderately toxic to the pathogens Staphylococcus aureus, Bacillus subtilis, Salmonella Typhimurium and Candida albicans, while the species Pseudomonas aeruginosa and Pseudomonas fluorescens, and the filamentous fungi Aspergillus parasiticus, Alternaria spp. and Fusarium verticillioides, were tolerant to these pigments. UV/visible spectral scanning and Fourier- transform infrared spectroscopy (FTIR) suggest the presence of reduced ommatin in methanol/ HCl extract with high intrinsic fluorescence.

Nutraceuticals/Drugs Promoting Mitophagy and Mitochondrial Biogenesis May Combat the Mitochondrial Dysfunction Driving Progression of Dry Age-Related Macular Degeneration.

In patients with age-related macular degeneration (AMD), the crucial retinal pigment epithelial (RPE) cells are characterized by mitochondria that are structurally and functionally defective. Moreover, deficient expression of the mRNA-editing enzyme Dicer is noted specifically in these cells. This Dicer deficit up-regulates expression of Alu RNA, which in turn damages mitochondria-inducing the loss of membrane potential, boosting oxidant generation, and causing mitochondrial DNA to translocate to the cytoplasmic region. The cytoplasmic mtDNA, in conjunction with induced oxidative stress, triggers a non-canonical pathway of NLRP3 inflammasome activation, leading to the production of interleukin-18 that acts in an autocrine manner to induce apoptotic death of RPE cells, thereby driving progression of dry AMD. It is proposed that measures which jointly up-regulate mitophagy and mitochondrial biogenesis (MB), by replacing damaged mitochondria with "healthy" new ones, may lessen the adverse impact of Alu RNA on RPE cells, enabling the prevention or control of dry AMD. An analysis of the molecular biology underlying mitophagy/MB and inflammasome activation suggests that nutraceuticals or drugs that can activate Sirt1, AMPK, Nrf2, and PPARα may be useful in this regard. These include ferulic acid, melatonin urolithin A and glucosamine (Sirt1), metformin and berberine (AMPK), lipoic acid and broccoli sprout extract (Nrf2), and fibrate drugs and astaxanthin (PPARα). Hence, nutraceutical regimens providing physiologically meaningful doses of several or all of the: ferulic acid, melatonin, glucosamine, berberine, lipoic acid, and astaxanthin, may have potential for control of dry AMD.

How do exercise training variables stimulate processes related to mitochondrial biogenesis in slow and fast trout muscle fibres?

NEW FINDINGS: What is the central question of this study? Exercise is known to promote mitochondrial biogenesis in skeletal muscle, but what are the most relevant training protocols to stimulate it? What is the main finding and its importance? As in mammals, training in rainbow trout affects slow and fast muscle fibres differently. Exercise intensity, relative to volume, duration and frequency, is the most relevant training variable to stimulate the processes related to mitochondrial biogenesis in both red and white muscles. This study offers new insights into muscle fibre type-specific transcription and expression of genes involved in mitochondrial adaptations following training. ABSTRACT: Exercise is known to be a powerful way to improve health through the stimulation of mitochondrial biogenesis in skeletal muscle, which undergoes cellular and molecular adaptations. One of the current challenges in human is to define the optimal training stimulus to improve muscle performance. Fish are relevant models for exercise training physiology studies mainly because of their distinct slow and fast muscle fibres. Using rainbow trout, we investigated the effects of six different training protocols defined by manipulating specific training variables (such as exercise intensity, volume, duration and frequency), on mRNAs and some proteins related to four subsystems (AMP-activated protein kinase-peroxisome proliferator-activated receptor γ coactivator-1α signalling pathway, mitochondrial function, antioxidant defences and lactate dehydrogenase (LDH) metabolism) in both red and white muscles (RM and WM, respectively). In both muscles, high-intensity exercise stimulated more mRNA types and enzymatic activities related to mitochondrial biogenesis than moderate-intensity exercise. For volume, duration and frequency variables, we demonstrated fibre type-specific responses. Indeed, for high-intensity interval training, RM transcript levels are increased by a low training volume, but WM transcript responses are stimulated by a high training volume. Moreover, transcripts and enzymatic activities related to mitochondria and LDH show that WM tends to develop aerobic metabolism with a high training volume. For transcript stimulation, WM requires a greater duration and frequency of exercise than RM, whereas protein adaptations are efficient with a long training duration and a high frequency in both muscles.

Nutraceutical Strategies for Suppressing NLRP3 Inflammasome Activation: Pertinence to the Management of COVID-19 and Beyond.

Inflammasomes are intracellular protein complexes that form in response to a variety of stress signals and that serve to catalyze the proteolytic conversion of pro-interleukin-1ß and pro-interleukin-18 to active interleukin-1ß and interleukin-18, central mediators of the inflammatory response; inflammasomes can also promote a type of cell death known as pyroptosis. The NLRP3 inflammasome has received the most study and plays an important pathogenic role in a vast range of pathologies associated with inflammation-including atherosclerosis, myocardial infarction, the complications of diabetes, neurological and autoimmune disorders, dry macular degeneration, gout, and the cytokine storm phase of COVID-19. A consideration of the molecular biology underlying inflammasome priming and activation enables the prediction that a range of nutraceuticals may have clinical potential for suppressing inflammasome activity-antioxidants including phycocyanobilin, phase 2 inducers, melatonin, and N-acetylcysteine, the AMPK activator berberine, glucosamine, zinc, and various nutraceuticals that support generation of hydrogen sulfide. Complex nutraceuticals or functional foods featuring a number of these agents may find utility in the prevention and control of a wide range of medical disorders.

Training protocols differently affect AMPK-PGC-1α signaling pathway and redox state in trout muscle.

Beneficial effects of physical exercise training are in part related to enhancement of muscle mitochondrial performance. The effects of two different trainings were investigated on transcripts and proteins of the AMPK-PGC-1α signaling pathway, the mitochondrial functioning (citrate synthase (CS), oxidative phosphorylation complexes, uncoupling proteins (UCP)) and the antioxidant defenses (superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase) in rainbow trout red and white skeletal muscles. One group of trouts swam for 10 days at a moderate intensity (approximately 57% Ucrit or 2.0 body lengths/s, 23.5 h/day) and another group at a high intensity (approximately 90% Ucrit or 3.2 body lengths/s, 2 h/day). In the red muscle, the increase of Cs mRNA levels was significantly correlated with the transcripts of Ampkα1, Ampkα2, Pgc-1α, the oxidative phosphorylation complexes, Ucp2α, Ucp2ß, Sod1, Sod2 and Gpx1. After 10 days of training, high intensity training (HIT) stimulates more the transcription of genes involved in this aerobic pathway than moderate intensity training (MIT) in the skeletal muscles, and mainly in the red oxidative muscle. However, no changes in CS, cytochrome c oxidase (COX) and antioxidant defenses activities and in oxidative stress marker (isoprostane plasmatic levels) were observed. The transcriptomic responses are fiber- and training-type dependent when proteins were not yet expressed after 10 days of training. As in mammals, our results suggest that HIT could promote benefit effects in fish.

Gender-dependent differences of mitochondrial function and oxidative stress in rat skeletal muscle at rest and after exercise training.

OBJECTIVE: This study investigated gender-dependent differences of mitochondrial function and sensitivity to in vitro ROS exposure in rat skeletal muscle at rest and after exercise training. METHODS: Wistar rats underwent running training for 6 weeks. In vitro measurements of hydroxyl radical production, oxygen consumption (under basal and maximal respiration conditions) and ATP production were made on permeabilized fibers. Mitochondrial function was examined after exposure and non-exposure to an in vitro generator system of reactive oxygen species (ROS). Antioxidant enzyme activities and malondialdehyde (MDA) content were also determined. RESULTS: Compared with sedentary males, females showed a greater resistance of mitochondrial function (oxygen consumption and ATP production) to ROS exposure, and lower MDA content and antioxidant enzyme activities. The training protocol had more beneficial effects in males than females with regard to ROS production and oxidative stress. In contrast to male rats, the susceptibility of mitochondrial function to ROS exposure in trained females was unchanged. DISCUSSION: Exercise training improves mitochondrial function oxidative capacities in both male and female rats, but is more pronounced in males as a result of different mechanisms. The resistance of mitochondrial function to in vitro oxidative stress exposure and the antioxidant responses are gender- and training-dependent, and may be related to the protective effects of estrogen.

Clinical, virological, and biological parameters associated with outcomes of Ebola virus infection in Macenta, Guinea.

BACKGROUND. The pathogenesis of Ebola virus (EBOV) disease (EVD) is poorly characterized. The establishment of well-equipped diagnostic laboratories close to Ebola treatment centers (ETCs) has made it possible to obtain relevant virological and biological data during the course of EVD and to assess their association with the clinical course and different outcomes of the disease. METHODS. We were responsible for diagnosing EBOV infection in patients admitted to two ETCs in forested areas of Guinea. The pattern of clinical signs was recorded, and an etiological diagnosis was established by RT-PCR for EBOV infection or a rapid test for malaria and typhoid fever. Biochemical analyses were also performed. RESULTS. We handled samples from 168 patients between November 29, 2014, and January 31, 2015; 97 patients were found to be infected with EBOV, with Plasmodium falciparum coinfection in 18%. Overall mortality for EVD cases was 58%, rising to 86% if P. falciparum was also present. Viral load was higher in fatal cases of EVD than in survivors, and fatal cases were associated with higher aspartate aminotransferase (AST) and alanine aminotransferase (ALT), C-reactive protein (CRP), and IL-6 levels. Furthermore, regardless of outcome, EVD was characterized by higher creatine kinase (CPK), amylase, and creatinine levels than in febrile patients without EVD, with higher blood urea nitrogen (BUN) levels in fatal cases of EVD only. CONCLUSION. These findings suggest that a high viral load at admission is a marker of poor EVD prognosis. In addition, high AST, ALT, CRP, and IL-6 levels are associated with a fatal outcome of EVD. Damage to the liver and other tissues, with massive rhabdomyolysis and, probably, acute pancreatitis, is associated with EVD and correlated with disease severity. Finally, biochemical analyses provide substantial added value at ETCs, making it possible to improve supportive rehydration and symptomatic care for patients. FUNDING. The French Ministry of Foreign Affairs, the Agence Française de Développement, and Institut Pasteur.

Resistance to root-knot nematodes Meloidogyne spp. in woody plants.

I. 42 II. 43 III. 44 IV. 47 V. 49 VI. 50 VII. 50 VIII. 50 IX. 52 52 References 52 SUMMARY: Root-knot nematodes (RKNs) Meloidogyne spp. cause major damage to cultivated woody plants. Among them, Prunus, grapevine and coffee are the crops most infested by worldwide polyphagous species and species with a more limited distribution and/or narrower host range. The identification and characterization of natural sources of resistance are important steps to develop RKN control strategies. In woody crops, resistant rootstocks genetically different from the scion of agronomical interest may be engineered. We describe herein the interactions between RKNs and different woody crops, and highlight the plant species in which resistance and corresponding resistance (R) genes have been discovered. Even though grapevine and, to a lesser extent, coffee have a history of rootstock selection for RKN resistance, few cases of resistance have been documented. By contrast, in Prunus, R genes with different spectra have been mapped in plums, peach and almond and can be pyramided for durable resistance in interspecific rootstocks. We particularly discuss here the Ma Toll/interleukin-1 receptor-like-nucleotide binding-leucine-rich repeat gene from Myrobalan plum, one of the longest plant R genes cloned to date, due to its unique biological and structural properties. RKN R genes in Prunus will enable us to carry out molecular studies aimed at improving our knowledge of plant immunity in woody plants.

Retino-protective effect of Bucida buceras against oxidative stress induced by H2O2 in human retinal pigment epithelial cells line.

BACKGROUND: Reactive Oxygen Species (ROS) impair the physiological functions of Retinal Pigment Epithelial (RPE) cells, which are known as one major cause of age-related macular degeneration and retinopathy diseases. The purpose of this study is to explore the cytoprotective effects of the antioxidant Bucida buceras extract in co-treatment with hydrogen peroxide (H2O2) delivery as a single addition or with continuous generation using glucose oxidase (GOx) in ARPE-19 cell cultures. The mechanism of Bucida buceras extract is believed to be associated with their antioxidant capacity to protect cells against oxidative stress. METHODS: A comparative oxidative stress H2O2-induced was performed by addition and enzymatic generation using glucose oxidase on human retinal pigment epithelial cells line. H2O2-induced injury was measured by toxic effects (cell death and apoptotic pathway) and intracellular redox status: glutathione (GSH), antioxidant enzymes (catalase and glutathione peroxidase) and reducing power (FRAP). The retino-protective effect of co-treatment with Bucida buceras extract on H2O2-induced human RPE cell injury was investigated by cell death (MTT assay) and oxidative stress biomarkers (H2O2, GSH, CAT, GPx and FRAP). RESULTS: Bucida buceras L. extract is believed to be associated with the ability to prevent cellular oxidative stress. When added as a pulse, H2O2 is rapidly depleted and the cytotoxicity analyses show that cells can tolerate short exposure to high peroxide doses delivered as a pulse but are susceptible to lower chronic doses. Co-treatment with Bucida buceras was able to protect the cells against H2O2-induced injury. In addition to preventing cell death treatment with antioxidant plant could also reverse the significant decrease in GSH level, catalase activity and reducing power caused by H2O2. CONCLUSION: These findings suggest that Bucida buceras could protect RPE against ocular pathogenesis associated with oxidative stress induced by H2O2-delivered by addition and enzymatic generation.

Effect of exercise training on oxidative stress and mitochondrial function in rat heart and gastrocnemius muscle.

OBJECTIVE: This study aimed to explore the effect of endurance training on oxidative parameters and mitochondrial function in gastrocnemius and heart muscle. METHODS: Male Wistar rats were trained by running for 6 weeks. In vitro measurements of the rates of hydroxyl radical ((•)OH) production, oxygen consumption (in either the absence, basal rate (V0), or the presence, maximal rate (Vmax), of adenosine diphosphate), and adenosine triphosphate (ATP) production were made simultaneously in permeabilized fibers. The mitochondrial function was explored after exposure or non-exposure to an in vitro generator system of reactive oxygen species (ROS). RESULTS: Vmax was not affected by training, but V0 decreased. In conditions of maximal mitochondrial functioning, an increase in ATP rate and a decrease in (•)OH production occurred simultaneously. In vitro ROS exposure disturbed mitochondrial function, but training modified the vulnerability of Vmax and ATP rate to ROS in different ways. DISCUSSION: We hypothesize that the part of Vmax devoted to proton leakage was decreased in trained rats, consequently improving ATP synthesis. The data suggest that, after training, there is more efficient use of electrons in respiratory chain energy production, rather than a greater ROS scavenging capacity.

Molecular characterization of HIV type 1 in Brazzaville, Republic of Congo, and first data on resistance to antiretroviral drugs.

One hundred patients have been enrolled in the CTA (ambulatory treatment center) of Brazzaville, Republic of Congo, from February to April 2011: 41 naive individuals and 59 patients at failure of first line regimen [two nucleoside reverse transcriptase inhibitors (NRTIs) plus one nonnucleoside reverse transcriptase inhibitor (NNRTI)]. Phylogenetic analysis of HIV-1 isolates allowed identification of subtypes and circulating recombinant forms (CRFs). The drug resistance mutations (DRMs) in reverse transcriptase and protease were analyzed in both subpopulations. Globally, 92 viruses were characterized, exhibiting a high diversity of HIV-1 with a majority of undetermined recombinant forms (URF) followed by CRF02_AG, CRF37_cpx, G, A1, B, D, H, and several other subtypes and CRF: F1, A2, C, CRF13_cpx, CRF11_cpx, CRF20_BG, CRF21_A2D, CRF33_01B G, CRF02_AG, CRF37_cpx, and A1. In naive patients, DRMs were observed with percentages ranging from 4% to 9% depending on drug classes. In treated patients at failure, numerous DRMs could be noted that induce actual or potential resistance to major NRTIs and NNRTIs.

Impact of malnutrition and social determinants on survival of HIV-infected adults starting antiretroviral therapy in resource-limited settings.

OBJECTIVES: Determining the impact of malnutrition, anaemia and social determinants on survival once starting antiretroviral therapy (ART) in a cohort of HIV-infected adults in a rural HIV care centre in Sihanoukville, Cambodia. METHODS: Retrospective and descriptive cohort study of adults starting ART between December 2004 and July 2009. We used the Kaplan-Meier and Cox regression survival analyses to identify predictors of death. RESULTS: Out of 1002 patients, 49.7% were men; median age was 40; median time of follow-up was 2.4 years and 10.4% died during the follow-up. At baseline, median CD4 cell count was 83 cells/µl, 79.9% were at WHO stage III or IV. In multivariate analysis, malnutrition appeared to be a strong and independent risk factor of death; 11.2% had a BMI less than 16 kg/m and hazard ratio was 6.97 [95% confidence interval (CI), 3.51-13.89], 21.5% had a BMI between 16 and 18 kg/m and hazard ratio was 2.88 (95% CI, 1.42-5.82), 30.8% had a BMI between 18 and 20 kg/m and hazard ratio was 2.18 (95% CI, 1.09-4.36). Severe anaemia (haemoglobin≤8.4 g/dl) and CD4 cell count below 100 cells/µl also predicted mortality, hazard ratio were 2.25 (95% CI, 1.02-4.34) and 2.29 (95% CI, 1.01-2.97), respectively. Social determinants were not significantly associated with death in univariate analysis. CONCLUSION: Malnutrition and anaemia are strong and independent prognostic factors at the time of starting ART. Nutritional cares are essential for the clinical success of HIV programs started in developing countries.

Effects of high-pressure acclimatization on silver eel (Anguilla anguilla, L.) slow muscle contraction.

As the spawning migration of the eel is supposed to correspond to a long swimming activity at depth, patterns of slow red muscle contraction have been investigated in European silver eel (Anguilla anguilla L.) exposed for 3 weeks to 10.1 MPa hydrostatic pressure. The results show that pressure-acclimated eels (male and female) show a three-fold decrease in maximum isometric stress of twitch and tetanic contractions while time to peak force, time from peak force to 90% relaxation and ratio of twitch tension to tetanic tension remain unchanged. The observed modifications in slow red muscle mechanical properties do not impede the spawning migration of the eel and are possibly partially compensated by an improvement in the efficiency of oxidative phosphorylation. Effects of changes in membrane fluidity are also discussed.