Spinal lymphangiomas: Case-based review of a chameleonic disease entity.

Purpose: Lymphangiomas are benign hamartomas in the spectrum of lymphatic malformations, exhibiting multifaceted clinical features. Spinal involvement is exceedingly rare, with only 35 cases reported to date. Both due to their rarity and chameleonic radiologic features, spinal lymphangiomas (SLs) are usually misdiagnosed; postoperatively, surgeons are thus confronted with an unexpected histopathological diagnosis with sparse pertinent literature and no treatment guidelines available. Methods: Here, we report the case of a 67-year-old female who underwent surgery for a T6-T7 epidural SL with transforaminal extension, manifesting with spastic paraparesis. Then, we present the results of the first systematic review of the literature on this subject, delineating the clinical and imaging features and the therapeutic implications of this rare disease entity. Results: Our patient was treated with T6-T7 hemilaminectomy and resection of the epidural mass, with complete recovery of her neurological picture. No recurrence was evident at 18 months. In the literature, 35 cases of SL were reported that can be classified as vertebral SL (n = 18), epidural SL (n = 10), intradural SL (n = 3), or intrathoracic lymphangiomas with secondary spinal involvement (n = 4). Specific treatment strategies (both surgical and nonsurgical) were adopted in relation to each of these categories. Conclusion: Gathering knowledge about SL is fundamental to promote both correct preoperative identification and appropriate perioperative management of this rare disease entity. By reviewing the literature and discussing an exemplary case, we delineate a framework that can guide surgeons facing such an unfamiliar diagnosis.

Functional redundancy of seasonal vitamin B12 biosynthesis pathways in coastal marine microbial communities.

Vitamin B12 (cobalamin) is a major cofactor required by most marine microbes, but only produced by a few prokaryotes in the ocean, which is globally B12 -depleted. Despite the ecological importance of B12 , the seasonality of B12 metabolisms and the organisms involved in its synthesis in the ocean remain poorly known. Here we use metagenomics to assess the monthly dynamics of B12 -related pathways and the functional diversity of associated microbial communities in the coastal NW Mediterranean Sea over 7 years. We show that genes related to potential B12 metabolisms were characterized by an annual succession of different organisms carrying distinct production pathways. During the most productive winter months, archaea (Nitrosopumilus and Nitrosopelagicus) were the main contributors to B12 synthesis potential through the anaerobic pathway (cbi genes). In turn, Alphaproteobacteria (HIMB11, UBA8309, Puniceispirillum) contributed to B12 synthesis potential in spring and summer through the aerobic pathway (cob genes). Cyanobacteria could produce pseudo-cobalamin from spring to autumn. Finally, we show that during years with environmental perturbations, the organisms usually carrying B12 synthesis genes were replaced by others having the same gene, thus maintaining the potential for B12 production. Such ecological insurance could contribute to the long-term functional resilience of marine microbial communities exposed to contrasting inter-annual environmental conditions.

Genetic and physiological responses to light quality in a deep ocean ecotype of Ostreococcus, an ecologically important photosynthetic picoeukaryote.

Phytoplankton are exposed to dramatic variations in light quality when cells are carried by upwelling or downwelling currents or encounter sediment. We investigated the potential impact of light quality changes in Ostreococcus, a key marine photosynthetic picoeukaryote, by analysing changes in its transcriptome, pigment content, and photophysiology after acclimation to monochromatic red, green, or blue light. The clade B species RCC809, isolated from the deep euphotic zone of the tropical Atlantic Ocean, responded to blue light by accelerating cell division at the expense of storage reserves and by increasing the relative level of blue-light-absorbing pigments. It responded to red and green light by increasing its potential for photoprotection. In contrast, the clade A species OTTH0595, which originated from a shallow water environment, showed no difference in photosynthetic properties and minor differences in carotenoid contents between light qualities. This was associated with the loss of candidate light-quality responsive promoter motifs identified in RCC809 genes. These results demonstrate that light quality can have a major influence on the physiology of eukaryotic phytoplankton and suggest that different light quality environments can drive selection for diverse patterns of responsiveness and environmental niche partitioning.

Interaction of Chondroitin and Hyaluronan Glycosaminoglycans with Surfaces of Carboxylated Carbon Nanotubes Studied Using Molecular Dynamics Simulations.

Interaction of ß-D-glucopyranuronic acid (GlcA), N-acetyl-ß-D-glucosamine (GlcNAc), N-acetyl-ß-D-galactosamine (GalNAc) and two natural decameric glycosaminoglycans, hyaluronic acid (HA) and Chondroitin (Ch) with carboxylated carbon nanotubes, were studied using molecular dynamics simulations in a condensed phase. The force field used for carbohydrates was the GLYCAM-06j version, while functionalized carbon nanotubes (fCNT) were described using version two of the general amber force field. We found a series of significant differences in carbohydrate-fCNT adsorption strength depending on the monosaccharide molecule and protonation state of surface carboxyl groups. GlcNAc and GalNAc reveal a strong adsorption on fCNT with deprotonated carboxyl groups, and a slightly weaker adsorption on the fCNT with protonated carboxyl groups. On the contrary, GlcA weakly adsorbs on fCNT. The change in protonation state of surface carboxyl groups leads to the reversal orientation of GlcNAc and GalNAc in reference to the fCNT surface, while GlcA is not sensitive to that factor. Adsorption of decameric oligomers on the surface of fCNT weakens with the increasing number of monosaccharide units. Chondroitin adsorbs weaker than hyaluronic acid and incorporation of four Ch molecules leads to partial detachment of them from the fCNT surface. The glycan-fCNT interactions are strong enough to alter the conformation of carbohydrate backbone; the corresponding conformational changes act toward a more intensive contact of glycan with the fCNT surface. Structural and energetic features of the adsorption process suggest the CH-π interaction-driven mechanism.

Impact of the Ileal Microbiota on Surgical Site Infections in Crohn's Disease: A Nationwide Prospective Cohort.

BACKGROUND AND AIMS: Surgery is performed in 50-70% of Crohn's disease [CD] patients, and its main risk is surgical site infection [SSI]. The microbiota has been extensively assessed in CD but not as a potential risk factor for septic morbidity. The objective of this study was to assess the impact of the gut microbiota on SSI in CD. METHODS: We used the multicentric REMIND prospective cohort to identify all patients who experienced SSI after ileocolonic resection for CD, defined as any postoperative local septic complication within 90 days after surgery: wound abscess, intra-abdominal collection, anastomotic leakage or enterocutaneous fistula. The mucosa-associated microbiota of the ileal resection specimen was analysed by 16S gene sequencing in 149 patients. The variable selection and prediction were performed with random forests [R package VSURF] on clinical and microbiotal data. The criterion of performance that we considered was the area under the Receiver Operating Characteristic [ROC] curve [AUC]. RESULTS: SSI occurred in 24 patients [16.1%], including 15 patients [10.1%] with major morbidity. There were no significant differences between patients with or without SSI regarding alpha and beta diversity. The top selected variables for the prediction of SSI were all microbiota-related. The maximum AUC [0.796] was obtained with a model including 14 genera, but an AUC of 0.78 had already been obtained with a model including only six genera [Hungatella, Epulopiscium, Fusobacterium, Ruminococcaceae_ucg_009, Actinomyces and Ralstonia]. CONCLUSION: The gut microbiota has the potential to predict SSI after ileocolonic resection for CD. It might play a role in this frequent postoperative complication.

The "STARS-CASCADE" Study: Virtual Reality Simulation as a New Training Approach in Vascular Neurosurgery.

OBJECTIVE: Surgical clipping has become a relatively rare procedure in comparison to endovascular exclusion of cerebral aneurysms. Consequently, there is a declining number of cases where young neurosurgeons can practice clipping. For this reason, we investigated the application of a new 3-dimensional (3D) simulation and rehearsal device, Surgical Theater, in vascular neurosurgery. METHODS: We analyzed data of 20 patients who underwent surgical aneurysm clipping. In 10 cases, Surgical Theater was used to perform the preoperative 3D planning (CASCADE group), while traditional imaging was used in the other cases (control group). Preoperative 3D simulation was performed by 4 expert and 3 junior neurosurgeons (1 fellow, 2 residents). During postoperative debriefings, expert surgeons explained the different aspects of the operation to their younger colleagues in an interactive way using the simulator. Questionnaires were given to the surgeons to get qualitative feedback about the simulator, and the junior surgeons' performance at simulator was also analyzed. RESULTS: There were no differences in surgery outcomes, complications, and surgical duration (P > 0.05) between the 2 groups. Senior neurosurgeons performed similarly when operating at the simulator as compared with in the operating room, while junior neurosurgeons improved their performance at the simulator after the debriefing session (P < 0.005). CONCLUSIONS: Surgical Theater proved to be realistic in replicating vascular neurosurgery scenarios for rehearsal and simulation purposes. Moreover, it was shown to be useful for didactic purposes, allowing young neurosurgeons to take full advantage and learn from senior colleagues to become familiar with this demanding neurosurgical subspecialty.

Seasonal marine microorganisms change neighbours under contrasting environmental conditions.

Marine picoplankton contribute to global carbon sequestration and nutrient recycling. These processes are directly related to the composition of communities, which in turn depends on microbial interactions and environmental forcing. Under regular seasonal cycles, marine communities show strong predictable patterns of annual re-occurrences, but little is known about the effect of environmental perturbation on their organization. The aim of our study was to investigate the co-occurrence patterns of planktonic picoeukaryote, bacteria and archaea under contrasting environmental conditions. The study was designed to have high sampling frequency that could match both the biological rhythm of marine microbes and the short time scale of extreme weather events. Our results show that microbial networks changed from year to year depending on conditions. In addition, individual taxa became less interconnected and changed neighbours, which revealed an unfaithful relationship between marine microorganisms. This unexpected pattern suggests possible switches between organisms that have similar specific functions, or hints at the presence of organisms that share similar environmental niches without interacting. Despite the observed annual changes, the time series showed re-occurring communities that appear to recover from perturbations. Changing co-occurrence patterns between marine microorganisms may allow the long-term stability of ecosystems exposed to contrasting meteorological events.

The Impact of Neuronavigation on the Surgical Outcome of Microvascular Decompression for Trigeminal Neuralgia.

OBJECTIVE: Microvascular decompression (MVD) is considered the only etiological treatment for drug-resistant trigeminal neuralgia (TN). Nonetheless, despite the recent technological advances, the risks associated with MVD remain non-negligible. The aim of this study was to evaluate the impact of using neuronavigation on the surgical outcomes of patients with TN submitted for MVD. METHODS: We analyzed 30 consecutive patients (11 men, 19 women) who underwent MVD for TN between January 2019 and December 2019. Patients were divided in 2 groups according to the use of neuronavigation (group A: MVD with neuronavigation; group B: MVD without neuronavigation). The impact of neuronavigation was assessed on the following parameters: craniotomy size, surgical duration, mastoid air cell opening, postoperative cerebrospinal fluid (CSF) leakage and other complications occurrence, and length of hospitalization. The acute pain relief and the Barrow Neurological Institute score at follow-up were used to evaluate the functional outcome. RESULTS: The craniotomy size, the surgical duration, and the CSF leak incidence were significantly reduced in group A compared with group B (P = 0.0009, P = 0.0369, and P = 0.0406, respectively). The incidence of mastoid air cell opening, and the length of hospitalization were reduced in group A compared with group B, although these differences were not statistically significant. We obtained an acute pain relief in all cases, and the Barrow Neurological Institute score at follow-up was significantly reduced (P < 0.0001). CONCLUSIONS: Neuronavigation is a useful tool that significantly reduced craniotomy size, surgical duration, and CSF leak incidence in patients with TN submitted for MVD. We advise to routinely implement neuronavigation in this type of surgery.

The interplay between iron limitation, light and carbon in the proteorhodopsin-containing Photobacterium angustum S14.

Iron (Fe) limitation is known to affect heterotrophic bacteria within the respiratory electron transport chain, therefore strongly impacting the overall intracellular energy production. We investigated whether the gene expression pattern of the light-sensitive proton pump, proteorhodopsin (PR), is influenced by varying light, carbon and Fe concentrations in the marine bacterium Photobacterium angustum S14 and whether PR can alleviate the physiological processes associated with Fe starvation. Our results show that the gene expression of PR increases as cells enter the stationary phase, irrespective of Fe-replete or Fe-limiting conditions. This upregulation is coupled to a reduction in cell size, indicating that PR gene regulation is associated with a specific starvation-stress response. We provide experimental evidence that PR gene expression does not result in an increased growth rate, cell abundance, enhanced survival or ATP concentration within the cell in either Fe-replete or Fe-limiting conditions. However, independent of PR gene expression, the presence of light did influence bacterial growth rates and maximum cell abundances under varying Fe regimes. Our observations support previous results indicating that PR phototrophy seems to play an important role within the stationary phase for several members of the Vibrionaceae family, but that the exact role of PR in Fe limitation remains to be further explored.

Publisher Correction: Genetic tool development in marine protists: emerging model organisms for experimental cell biology.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Genetic tool development in marine protists: emerging model organisms for experimental cell biology.

Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways.

Mesh Repair in Crohn's Disease: A Case-Matched Multicenter Study in 234 Patients.

BACKGROUND: There are no specific guidelines for ventral hernia management in Crohn's disease (CD) patients. We aimed to assess the risk of septic morbidity after mesh repair in CD. METHODS: This was a retrospective multicentre study comparing CD and non-CD patients undergoing mesh repair for ventral hernia (primary or incisional hernia). Controls were matched 1:1 for the presence of a stoma, history of surgical sepsis, hernia size and Ventral Hernia Working Group (VHWG) score. All demographic, pre-, intra- and postoperative data were retrieved, including long-term data. RESULTS: We included 234 patients, with 114 CD patients. Both groups had comparable VHWG scores (p = 0.12), hernia sizes (p = 0.11), ASA scores ≥ 3 (p = 0.70), body mass index values (p = 0.14), presence of stoma (CD 21.9% vs. controls 15%, p = 0.16), history of sepsis (14% vs. 6.7%, p = 0.23), rates of malnutrition (4.4% vs. 1.7%, p = 0.46), rates of incisional hernia (93% vs. 95%, p = 0.68) and concomitant procedures (18.4% vs. 11.7%, p = 0.12). CD patients carried a higher risk of postoperative septic morbidity (18.4% vs. 5%, p = 0.001), entero-prosthetic fistula (7% vs. 0, p < 0.01) and mesh withdrawals (5.3% vs. 0, p = 0.011). Ventral hernia recurrence rates were similar (14% vs. 8.3%, p = 0.15). In the univariate analysis, the risk factors for septic morbidity were CD (p = 0.001), malnutrition (p = 0.004), use of biological mesh (p < 0.0001) and concomitant procedure (p = 0.004). The mesh position, the means used for mesh fixation as well as the presence of a stoma were not identified as risk factors. CONCLUSIONS: CD seems to be a risk factor for septic morbidity after mesh repair.

Prospective memory and brain metastases: a relevant target for rehabilitation in post-operative patients?

PURPOSE: The study investigated the prospective memory (PM) functioning among patients with brain metastases (BM), eligible for neurosurgy/radiosurgery, and its relationships with depression and quality of life (QoL). METHODS: This case-healthy-control, cross-sectional study, comprised 160 participants, including 49 patients with BM from various cancers treated with neurosurgery or radiosurgery. They were compared with 111 matched controls on a set of neuropsychological tests, including the MoCA global cognitive test and an experimental PM task 'PROMESSE'. Participants also completed a depression scale (BDI-II), a generic (SF-12) and a specific (QLQ-C30) QoL instrument for cancer patients. Multivariate analyses were conducted on various PM outcomes, in particular on event-based (EBPM) and time-based (TBPM) PM performances. RESULTS: After adjusting for age and socio-cultural level, patients with BM performed worse than the control on the PM task (p < .0001) [OR 1.05; 95%CI (1.01-1.08)], whatever the location of BM (frontal versus temporal lobe). Patients with infratentorial BM exhibited better TBPM performances than patients with supratentorial BM (p = .02). The global PM performance was positively correlated with the MoCA (r = .45) and the SF-12 global score (r = .34), and negatively with the BDI-II score (r = - .20), the number of BM (r = - .34) and the volumetric of the BM (r = - 29). The TBPM performance was linked to the global QoL (r = .40) in patients. CONCLUSION: The study showed a significant PM deficit in patients with BM eligible for a neurosurgy/radiosurgery, which is linked to damaged QoL and which likely maintains some depressive affects. Prospective memory rehabilitation program should especially focus on TBPM for post-operative patients with BM.

Acute presentations of intradural lipomas: case reports and a review of the literature.

BACKGROUND: Lumbosacral lipomas (LLs) may remain asymptomatic or lead to progressive neurological deterioration. However, sudden neurological deterioration is a rare and severe event. Herein, we report rare occurrences of sudden clinical deterioration in two previously asymptomatic children harbouring intradural LLs without dermal sinus tracts or signs of occult dysraphism. A review of the pertinent literature is also included. CASE PRESENTATION: One child exhibited acute deterioration because of an epidural abscess associated with a filar lipoma without a sinus tract (probably caused by haematogenous spreading from a respiratory tract multiple infection), and the other child exhibited acute deterioration because of a very large, holocord syringomyelia-like cyst associated with a small conus lipoma. Both patients were 4 years old. In case #2, a previously undetected, severe tethered cord (conus at the S3-S4 level) was also present. A complete recovery was attained after an urgent surgical operation in both cases (in addition to targeted antibiotic therapy in case #1). All cases of deterioration in the literature were caused by abscess formation in dermal sinus tracts. CONCLUSIONS: Prophylactic surgery may be indicated even in asymptomatic children that have tethered cord and surgically favourable LLs (small dorsal and filar LLs), especially if the conditions are associated with progressive syringomyelia. Similarly, intradural dermal sinus tracts should be regarded as surgery-indicated, even if the conus is in its normal position and the patient is asymptomatic because there is a consistent risk of severe, infection-related complications. Finally, asymptomatic patients with filar LLs and a normally located conus can be candidates for surgery or an accurate clinical and radiological follow-up.

Efficacy and Safety of Two Neoadjuvant Strategies With Bevacizumab in MRI-Defined Locally Advanced T3 Resectable Rectal Cancer: Final Results of a Randomized, Noncomparative Phase 2 INOVA Study.

BACKGROUND: Recurrence and distant metastases remain a significant issue in locally advanced rectal cancer (LARC). Several multimodal strategies are assessed in clinical trials. PATIENTS AND METHODS: Patients with mid/low magnetic resonance imaging-defined high-risk LARC were randomized to arm A (12-week bevacizumab + FOLFOX-4 then bevacizumab-5-fluorouracil [5-FU]-radiotherapy [RT] before total mesorectal excision [TME]) or arm B (bevacizumab-5-FU-RT then TME). Long-term efficacy and safety up to 5 years' follow-up are reported. No comparison between arms was planned. RESULTS: Overall, 91 patients (46 in arm A and 45 in arm B) were included. Main results have been presented previously. During the late follow-up period (> 4 weeks after surgery), 4 patients (8.7%) in arm A and 4 (8.9%) in arm B experienced grade 3/4 adverse events related to bevacizumab; the most frequent were 2 anastomotic fistulas (both in arm A) and abscesses (1 in arm A and 2 in arm B). At 5 years' follow-up, 9 (19.6%) and 11 (24.4%) patients in arms A and B developed a fistula in the year after surgery, and 2 (4.3%) in arm A at > 1 year after surgery. Most resolved before study end. Five-year disease-free survival was 70% and 64.3% in arms A and B, respectively. Five-year overall survival was 90.5% (95% confidence interval, 76.7, 96.3) in arm A and 72.7% (95% confidence interval, 56.0, 83.9) in arm B. CONCLUSION: Neoadjuvant bevacizumab + FOLFOX-4 may have the potential to increase survival outcomes when followed by bevacizumab-5-FU-RT and TME in LARC. Bevacizumab-5-FU-RT then TME was associated with a higher-than-projected rate of anastomotic fistulas. Further research of neoadjuvant strategies in LARC is encouraged.

bHLH-PAS protein RITMO1 regulates diel biological rhythms in the marine diatom Phaeodactylum tricornutum.

Periodic light-dark cycles govern the timing of basic biological processes in organisms inhabiting land as well as the sea, where life evolved. Although prominent marine phytoplanktonic organisms such as diatoms show robust diel rhythms, the mechanisms regulating these processes are still obscure. By characterizing a Phaeodactylum tricornutum bHLH-PAS nuclear protein, hereby named RITMO1, we shed light on the regulation of the daily life of diatoms. Alteration of RITMO1 expression levels and timing by ectopic overexpression results in lines with deregulated diurnal gene expression profiles compared with the wild-type cells. Reduced gene expression oscillations are also observed in these lines in continuous darkness, showing that the regulation of rhythmicity by RITMO1 is not directly dependent on light inputs. We also describe strong diurnal rhythms of cellular fluorescence in wild-type cells, which persist in continuous light conditions, indicating the existence of an endogenous circadian clock in diatoms. The altered rhythmicity observed in RITMO1 overexpression lines in continuous light supports the involvement of this protein in circadian rhythm regulation. Phylogenetic analysis reveals a wide distribution of RITMO1-like proteins in the genomes of diatoms as well as in other marine algae, which may indicate a common function in these phototrophs. This study adds elements to our understanding of diatom biology and offers perspectives to elucidate timekeeping mechanisms in marine organisms belonging to a major, but under-investigated, branch of the tree of life.

Rhythmicity of coastal marine picoeukaryotes, bacteria and archaea despite irregular environmental perturbations.

Seasonality in marine microorganisms has been classically observed in phytoplankton blooms, and more recently studied at the community level in prokaryotes, but rarely investigated at the scale of individual microbial taxa. Here we test if specific marine eukaryotic phytoplankton, bacterial and archaeal taxa display yearly rhythms at a coastal site impacted by irregular environmental perturbations. Our seven-year study in the Bay of Banyuls (North Western Mediterranean Sea) shows that despite some fluctuating environmental conditions, many microbial taxa displayed significant yearly rhythms. The robust rhythmicity was found in both autotrophs (picoeukaryotes and cyanobacteria) and heterotrophic prokaryotes. Sporadic meteorological events and irregular nutrient supplies did, however, trigger the appearance of less common non-rhythmic taxa. Among the environmental parameters that were measured, the main drivers of rhythmicity were temperature and day length. Seasonal autotrophs may thus be setting the pace for rhythmic heterotrophs. Similar environmental niches may be driving seasonality as well. The observed strong association between Micromonas and SAR11, which both need thiamine precursors for growth, could be a first indication that shared nutritional niches may explain some rhythmic patterns of co-occurrence.

Author Correction: Carboxythiazole is a key microbial nutrient currency and critical component of thiamin biosynthesis.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Carboxythiazole is a key microbial nutrient currency and critical component of thiamin biosynthesis.

Almost all cells require thiamin, vitamin B1 (B1), which is synthesized via the coupling of thiazole and pyrimidine precursors. Here we demonstrate that 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole-2-carboxylic acid (cHET) is a useful in vivo B1 precursor for representatives of ubiquitous marine picoeukaryotic phytoplankton and Escherichia coli - drawing attention to cHET as a valuable exogenous micronutrient for microorganisms with ecological, industrial, and biomedical value. Comparative utilization experiments with the terrestrial plant Arabidopsis thaliana revealed that it can also use exogenous cHET, but notably, picoeukaryotic marine phytoplankton and E. coli were adapted to grow on low (picomolar) concentrations of exogenous cHET. Our results call for the modification of the conventional B1 biosynthesis model to incorporate cHET as a key precursor for B1 biosynthesis in two domains of life, and for consideration of cHET as a microbial micronutrient currency modulating marine primary productivity and community interactions in human gut-hosted microbiomes.

Comparative Analysis of Culture Conditions for the Optimization of Carotenoid Production in Several Strains of the Picoeukaryote Ostreococcus.

Microalgae are promising sources for the sustainable production of compounds of interest for biotechnologies. Compared to higher plants, microalgae have a faster growth rate and can be grown in industrial photobioreactors. The microalgae biomass contains specific metabolites of high added value for biotechnology such as lipids, polysaccharides or carotenoid pigments. Studying carotenogenesis is important for deciphering the mechanisms of adaptation to stress tolerance as well as for biotechnological production. In recent years, the picoeukaryote Ostreococcustauri has emerged as a model organism thanks to the development of powerful genetic tools. Several strains of Ostreococcus isolated from different environments have been characterized with respect to light response or iron requirement. We have compared the carotenoid contents and growth rates of strains of Ostreococcus (OTTH595, RCC802 and RCC809) under a wide range of light, salinity and temperature conditions. Carotenoid profiles and productivities varied in a strain-specific and stress-dependent manner. Our results also illustrate that phylogenetically related microalgal strains originating from different ecological niches present specific interests for the production of specific molecules under controlled culture conditions.