Responses of physiological groups of tropical heterotrophic bacteria to temperature and dissolved organic matter additions: food matters more than warming.

Compared to higher latitudes, tropical heterotrophic bacteria may be less responsive to warming because of strong bottom-up control. In order to separate both drivers, we determined the growth responses of bacterial physiological groups to temperature after adding dissolved organic matter (DOM) from mangroves, seagrasses and glucose to natural seawater from the Great Barrier Reef. Low (LNA) and high (HNA) nucleic acid content, membrane-intact (Live) and membrane-damaged (Dead) plus actively respiring (CTC+) cells were monitored for 4 days. Specific growth rates of the whole community were significantly higher (1.9 day-1 ) in the mangrove treatment relative to the rest (0.2-0.4 day-1 ) at in situ temperature and their temperature dependence, estimated as activation energy, was also consistently higher. Strong bottom-up control was suggested in the other treatments. Cell size depended more on DOM than temperature. Mangrove DOM resulted in significantly higher contributions of Live, HNA and CTC+ cells to total abundance, while the seagrass leachate reduced Live cells below 50%. Warming significantly decreased Live and CTC+ cells contributions in most treatments. Our results suggest that only in the presence of highly labile compounds, such as mangroves DOM, can we anticipate increases in heterotrophic bacteria biomass in response to warming in tropical regions.

Revealing hydrogen peroxide as an external stressor in macrophyte-dominated coastal ecosystems.

Benthic primary producers in coastal ecosystems provide important habitat for marine organisms through the provision of complex 3D habitat. Primary producers produce organic matter, while simultaneously producing reactive oxygen species, including hydrogen peroxide (H2O2), a driver of oxidative stress. Through their high biomass, productivity and effect on local hydrodynamics, benthic primary producers can potentially increase H2O2 concentrations surrounding the biogenic structures they form. The aim of this study was to identify the potential role of H2O2 produced by benthic primary producers as an external stressor in coastal ecosystems. This was achieved by measuring H2O2 concentrations within sea lettuce blooms (Ulva sp.), giant kelp forests (Macrocystis pyrifera), and seagrass meadows (Zostera muelleri); quantifying H2O2 production rates of these species; and testing heterotrophic bacterial response to relevant H2O2 concentrations. Ulva sp. produced five times more H2O2 than other species. At in situ concentrations, H2O2 inhibited bacterial production and carbon flow through the microbial loop by 75%. This study reveals H2O2 as an additional stressor in bloom-forming Ulva sp. with higher H2O2 production compared to the ecosystem engineers M. pyrifera and Z. muelleri. H2O2 production by benthic primary producers can affect carbon flow through the microbial loop, with the potential to propagate a stress signal up the food web.

Comparative proteomics reveals signature metabolisms of exponentially growing and stationary phase marine bacteria.

Much of the phenotype of a microorganism consists of its repertoire of metabolisms and how and when its proteins are deployed under different growth conditions. Hence, analyses of protein expression could provide important understanding of how bacteria adapt to different environmental settings. To characterize the flexibility of proteomes of marine bacteria, we investigated protein profiles of three important marine bacterial lineages - Oceanospirillaceae (Neptuniibacter caesariensis strain MED92), Roseobacter (Phaeobacter sp. MED193) and Flavobacteria (Dokdonia sp. MED134) - during transition from exponential to stationary phase. As much as 59-80% of each species' total proteome was expressed. Moreover, all three bacteria profoundly altered their expressed proteomes during growth phase transition, from a dominance of proteins involved in translation to more diverse proteomes, with a striking appearance of enzymes involved in different nutrient-scavenging metabolisms. Whereas the three bacteria shared several overarching metabolic strategies, they differed in important details, including distinct expression patterns of membrane transporters and proteins in carbon and phosphorous metabolism and storage compounds. These differences can be seen as signature metabolisms - metabolisms specific for lineages. These findings suggest that quantitative proteomics can inform about the divergent ecological strategies of marine bacteria in adapting to changes in environmental conditions.

Stimulation of growth by proteorhodopsin phototrophy involves regulation of central metabolic pathways in marine planktonic bacteria.

Proteorhodopsin (PR) is present in half of surface ocean bacterioplankton, where its light-driven proton pumping provides energy to cells. Indeed, PR promotes growth or survival in different bacteria. However, the metabolic pathways mediating the light responses remain unknown. We analyzed growth of the PR-containing Dokdonia sp. MED134 (where light-stimulated growth had been found) in seawater with low concentrations of mixed [yeast extract and peptone (YEP)] or single (alanine, Ala) carbon compounds as models for rich and poor environments. We discovered changes in gene expression revealing a tightly regulated shift in central metabolic pathways between light and dark conditions. Bacteria showed relatively stronger light responses in Ala compared with YEP. Notably, carbon acquisition pathways shifted toward anaplerotic CO2 fixation in the light, contributing 31 ± 8% and 24 ± 6% of the carbon incorporated into biomass in Ala and YEP, respectively. Thus, MED134 was a facultative double mixotroph, i.e., photo- and chemotrophic for its energy source and using both bicarbonate and organic matter as carbon sources. Unexpectedly, relative expression of the glyoxylate shunt genes (isocitrate lyase and malate synthase) was >300-fold higher in the light--but only in Ala--contributing a more efficient use of carbon from organic compounds. We explored these findings in metagenomes and metatranscriptomes and observed similar prevalence of the glyoxylate shunt compared with PR genes and highest expression of the isocitrate lyase gene coinciding with highest solar irradiance. Thus, regulatory interactions between dissolved organic carbon quality and central metabolic pathways critically determine the fitness of surface ocean bacteria engaging in PR phototrophy.

Disentangling seasonal bacterioplankton population dynamics by high-frequency sampling.

Multiyear comparisons of bacterioplankton succession reveal that environmental conditions drive community shifts with repeatable patterns between years. However, corresponding insight into bacterioplankton dynamics at a temporal resolution relevant for detailed examination of variation and characteristics of specific populations within years is essentially lacking. During 1 year, we collected 46 samples in the Baltic Sea for assessing bacterial community composition by 16S rRNA gene pyrosequencing (nearly twice weekly during productive season). Beta-diversity analysis showed distinct clustering of samples, attributable to seemingly synchronous temporal transitions among populations (populations defined by 97% 16S rRNA gene sequence identity). A wide spectrum of bacterioplankton dynamics was evident, where divergent temporal patterns resulted both from pronounced differences in relative abundance and presence/absence of populations. Rates of change in relative abundance calculated for individual populations ranged from 0.23 to 1.79 day(-1) . Populations that were persistently dominant, transiently abundant or generally rare were found in several major bacterial groups, implying evolution has favoured a similar variety of life strategies within these groups. These findings suggest that high temporal resolution sampling allows constraining the timescales and frequencies at which distinct populations transition between being abundant or rare, thus potentially providing clues about physical, chemical or biological forcing on bacterioplankton community structure.

Dynamics of metabolic activities and gene expression in the Roseobacter clade bacterium Phaeobacter sp. strain MED193 during growth with thiosulfate.

Metagenomic analyses of surface seawater reveal that genes for sulfur oxidation are widespread in bacterioplankton communities. However, little is known about the metabolic processes used to exploit the energy potentially gained from inorganic sulfur oxidation in oxic seawater. We therefore studied the sox gene system containing Roseobacter clade isolate Phaeobacter sp. strain MED193 in acetate minimal medium with and without thiosulfate. The addition of thiosulfate enhanced the bacterial growth yields up to 40% in this strain. Concomitantly, soxB and soxY gene expression increased about 8-fold with thiosulfate and remained 11-fold higher than that in controls through stationary phase. At stationary phase, thiosulfate stimulated protein synthesis and anaplerotic CO2 fixation rates up to 5- and 35-fold, respectively. Several genes involved in anaplerotic CO2 fixation (i.e., pyruvate carboxylase, propionyl coenzyme A [CoA], and crotonyl-CoA carboxylase) were highly expressed during active growth, coinciding with high CO2 fixation rates. The high expression of key genes in the ethylmalonyl-CoA pathway suggests that this is an important pathway for the utilization of two-carbon compounds in Phaeobacter sp. MED193. Overall, our findings imply that Roseobacter clade bacteria carrying sox genes can use their lithotrophic potential to gain additional energy from sulfur oxidation for both increasing their growth capacity and improving their long-term survival.

Influence of Salinity on the Extracellular Enzymatic Activities of Marine Pelagic Fungi.

Even though fungi are ubiquitous in the biosphere, the ecological knowledge of marine fungi remains rather rudimentary. Also, little is known about their tolerance to salinity and how it influences their activities. Extracellular enzymatic activities (EEAs) are widely used to determine heterotrophic microbes' enzymatic capabilities and substrate preferences. Five marine fungal species belonging to the most abundant pelagic phyla (Ascomycota and Basidiomycota) were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). Due to their sensitivity and specificity, fluorogenic substrate analogues were used to determine hydrolytic activity on carbohydrates (ß-glucosidase, ß-xylosidase, and N-acetyl-ß-D-glucosaminidase); peptides (leucine aminopeptidase and trypsin); lipids (lipase); organic phosphorus (alkaline phosphatase), and sulfur compounds (sulfatase). Afterwards, kinetic parameters such as maximum velocity (Vmax) and half-saturation constant (Km) were calculated. All fungal species investigated cleaved these substrates, but some species were more efficient than others. Moreover, most enzymatic activities were reduced in the saline medium, with some exceptions like sulfatase. In non-saline conditions, the average Vmax ranged between 208.5 to 0.02 µmol/g biomass/h, and in saline conditions, 88.4 to 0.02 µmol/g biomass/h. The average Km ranged between 1553.2 and 0.02 µM with no clear influence of salinity. Taken together, our results highlight a potential tolerance of marine fungi to freshwater conditions and indicate that changes in salinity (due to freshwater input or evaporation) might impact their enzymatic activities spectrum and, therefore, their contribution to the oceanic elemental cycles.

Decoupling between the genetic potential and the metabolic regulation and expression in microbial organic matter cleavage across microbiomes.

Metagenomics, metatranscriptomics, and metaproteomics are used to explore the microbial capability of enzyme secretion, but the links between protein-encoding genes and corresponding transcripts/proteins across ecosystems are underexplored. By conducting a multi-omics comparison focusing on key enzymes (carbohydrate-active enzymes [CAZymes] and peptidases) cleaving the main biomolecules across distinct microbiomes living in the ocean, soil, and human gut, we show that the community structure, functional diversity, and secretion mechanisms of microbial secretory CAZymes and peptidases vary drastically between microbiomes at metagenomic, metatranscriptomic, and metaproteomic levels. Such variations lead to decoupled relationships between CAZymes and peptidases from genetic potentials to protein expressions due to the different responses of key players toward organic matter sources and concentrations. Our results highlight the need for systematic analysis of the factors shaping patterns of microbial cleavage on organic matter to better link omics data to ecosystem processes. IMPORTANCE: Omics tools are used to explore adaptive mechanism of microbes in diverse systems, but the advantages and limitations of different omics tools remain skeptical. Here, we reported distinct profiles in microbial secretory enzyme composition revealed by different omics methods. In general, the predicted function from metagenomic analysis decoupled from the expression of corresponding transcripts/proteins. Linking omics results to taxonomic origin, functional capability, substrate specificity, secretion preference, and enzymatic activity measurement suggested the substrate's source, concentration and stoichiometry impose strong filtering on the expression of extracellular enzymes, which may overwrite the genetic potentials. Our results present an integrated perspective on the need for multi-dimensional characterization of microbial adaptation in a changing environment.

Metaproteomic analysis decodes trophic interactions of microorganisms in the dark ocean.

Proteins in the open ocean represent a significant source of organic matter, and their profiles reflect the metabolic activities of marine microorganisms. Here, by analyzing metaproteomic samples collected from the Pacific, Atlantic and Southern Ocean, we reveal size-fractionated patterns of the structure and function of the marine microbiota protein pool in the water column, particularly in the dark ocean (>200 m). Zooplankton proteins contributed three times more than algal proteins to the deep-sea community metaproteome. Gammaproteobacteria exhibited high metabolic activity in the deep-sea, contributing up to 30% of bacterial proteins. Close virus-host interactions of this taxon might explain the dominance of gammaproteobacterial proteins in the dissolved fraction. A high urease expression in nitrifiers suggested links between their dark carbon fixation and zooplankton urea production. In summary, our results uncover the taxonomic contribution of the microbiota to the oceanic protein pool, revealing protein fluxes from particles to the dissolved organic matter pool.

Two compound heterozygous variants in the CLN8 gene are responsible for neuronal cereidolipofuscinoses disorder in a child: a case report.

Background: Neuronal Ceroid Lipofuscinosis (NCL) disorders, recognized as the primary cause of childhood dementia globally, constitute a spectrum of genetic abnormalities. CLN8, a subtype within NCL, is characterized by cognitive decline, motor impairment, and visual deterioration. This study focuses on an atypical case with congenital onset and a remarkably slow disease progression. Methods: Whole-genome sequencing at 30× coverage was employed as part of a national genomics program to investigate the genetic underpinnings of rare diseases. This genomic approach aimed to challenge established classifications (vLINCL and EPMR) and explore the presence of a continuous phenotypic spectrum associated with CLN8. Results: The whole-genome sequencing revealed two novel likely pathogenic mutations in the CLN8 gene on chromosome 8p23.3. These mutations were not previously associated with CLN8-related NCL. Contrary to established classifications (vLINCL and EPMR), our findings suggest a continuous phenotypic spectrum associated with CLN8. Pathological subcellular markers further validated the genomic insights. Discussion: The identification of two previously undescribed likely pathogenic CLN8 gene mutations challenges traditional classifications and highlights a more nuanced phenotypic spectrum associated with CLN8. Our findings underscore the significance of genetic modifiers and interactions with unrelated genes in shaping variable phenotypic outcomes. The inclusion of pathological subcellular markers further strengthens the validity of our genomic insights. This research enhances our understanding of CLN8 disorders, emphasizing the need for comprehensive genomic analyses to elucidate the complexity of phenotypic presentations and guide tailored therapeutic strategies. The identification of new likely pathogenic mutations underscores the dynamic nature of CLN8-related NCL and the importance of individualized approaches to patient management.

Bacterial versus archaeal origin of extracellular enzymatic activity in the Northeast Atlantic deep waters.

We determined the total and dissolved extracellular enzymatic activity (EEA) of α-glucosidase and ß-glucosidase (AGase and BGase), alkaline phosphatase (APase) and leucine aminopeptidase (LAPase) activities in the epi-, meso- and bathypelagic waters of the subtropical Northeast Atlantic. EEA was also determined in treatments in which bacterial EEA was inhibited by erythromycin. Additionally, EEA decay experiments were performed with surface and deep waters to determine EEA lifetimes in both water masses. The proportion of dissolved to total EEA (66-89 %, 44-88 %, 57-82 % and 86-100 % for AGase, BGase, APase and LAPase, respectively) was generally higher than the cell-associated (i.e., particulate) EEA. The percentage of dissolved to total EEA was inversely proportional to the percentage of erythromycin-inhibited to total EEA. Since erythromycin-inhibited plus dissolved EEA equaled total EEA, this tentatively suggests that cell-associated EEA in the open oceanic water column is almost exclusively of bacterial origin. The decay constants of dissolved EEA were in the range of 0.002-0.048 h(-1) depending on the type of extracellular enzyme, temperature and depth in the water column. Although dissolved EEA can have different origins, the major contribution of Bacteria to cell-associated EEA and the long life-time of dissolved EEA suggest that Bacteria-and not mesophilic Archaea-are essentially the main producers of EEA in the open subtropical Northeast Atlantic down to bathypelagic layers.

[Neurological consequences of prematurity]. / Complicaciones neurológicas de la prematuridad.

Premature births are an important health indicator for a country. These children have a higher risk of mortality and morbidity. The main brain injuries in preterm infants include white matter injuries, intracranial hemorrhages, and cerebellar injuries. These injuries can be detected through brain ultrasound and magnetic resonance imaging (MRI), with MRI being the most sensitive technique. Perinatal brain injuries may have long-term consequences on the neurodevelopment of preterm infants, with an increased risk of cerebral palsy, cognitive, behavioral, sensory, and learning disorders, among others. It is key to implement prevention strategies and early intervention to reduce the negative consequences of brain injuries associated with prematurity. Key words: prematurity, periventricular leukomalacia, intracranial hemorrhage, neurodevelopmental disorders, cerebral palsy.

Los nacimientos prematuros representan un indicador importante de salud de un país. Estos niños tienen un mayor riesgo de mortalidad y morbilidad. Las principales lesiones encefálicas en los prematuros incluyen lesiones de la sustancia blanca, hemorragias intracraneanas y lesiones cerebelosas, que pueden ser detectadas mediante ecografía encefálica y resonancia magnética, siendo esta última la técnica más sensible. Estas lesiones pueden tener repercusión a largo plazo en el neurodesarrollo de los prematuros, con un mayor riesgo de parálisis cerebral, trastornos cognitivos, conductuales, sensoriales y del aprendizaje, entre otros. Es fundamental aplicar estrategias de prevención y atención temprana para reducir las consecuencias negativas de las lesiones encefálicas asociadas a la prematuridad.

Respiration, Production, and Growth Efficiency of Marine Pelagic Fungal Isolates.

Despite recent studies suggesting that marine fungi are ubiquitous in oceanic systems and involved in organic matter degradation, their role in the carbon cycle of the oceans is still not characterized and fungal respiration and production are understudied. This study focused on determining fungal growth efficiencies and its susceptibility to temperature differences and nutrient concentration. Hence, respiration and biomass production of three fungal isolates (Rhodotorula mucilaginosa, Rhodotorula sphaerocarpa, Sakaguchia dacryoidea) were measured in laboratory experiments at two temperatures and two nutrient concentrations. We found that fungal respiration and production rates differed among species, temperature, and nutrient concentration. Fungal respiration and production were higher at higher temperatures, but higher fungal growth efficiencies were observed at lower temperatures. Nutrient concentration affected fungal respiration, production, and growth efficiency, but its influence differed among species. Altogether, this study provides the first growth efficiency estimates of pelagic fungi, providing novel insights into the role of fungi as source/sink of carbon during organic matter remineralization. Further research is now needed to unravel the role of pelagic fungi in the marine carbon cycle, a topic that gains even more importance in times of increasing CO2 concentrations and global warming.

Fungal Diversity and Community Composition across Ecosystems.

Fungi have shaped the biosphere since the development of life on Earth. Despite fungi being present in all environments, most of the available fungal research has focused on soils. As a result, the role and composition of fungal communities in aquatic (marine and freshwater) environments remain largely unexplored. The use of different primers to characterise fungal communities has additionally complicated intercomparisons among studies. Consequently, we lack a basic global assessment of fungal diversity across major ecosystems. Here, we took advantage of a recently published 18S rRNA dataset comprising samples from major ecosystems (terrestrial, freshwater, and marine) to attempt a global assessment of fungal diversity and community composition. We found the highest fungal diversities for terrestrial > freshwater > marine environments, and pronounced gradients of fungal diversity along temperature, salinity, and latitude in all ecosystems. We also identified the most abundant taxa in each of these ecosystems, mostly dominated by Ascomycota and Basidiomycota, except in freshwater rivers where Chytridiomycota dominated. Collectively, our analysis provides a global analysis of fungal diversity across all major environmental ecosystems, highlighting the most distinct order and ASVs (amplicon sequencing variants) by ecosystem, and thus filling a critical gap in the study of the Earth's mycobiome.

The largely neglected ecological role of oceanic pelagic fungi.

Most investigations into ocean ecology and biogeochemistry have tended to focus on marine bacteria, archaea, and protists, while pelagic fungi (mycoplankton) have traditionally been neglected and considered to reside only in association with benthic solid substrates. Nevertheless, recent studies have revealed that pelagic fungi are distributed ubiquitously throughout the water column in every ocean basin and play an active role in the degradation of organic matter and the cycling of nutrients. We review the current status of knowledge on the ecology of mycoplankton and highlight knowledge gaps and challenges. These findings underscore the need to recognize this neglected kingdom as significant contributors to the organic matter cycling and ecology of the oceans.

Release of cell-free enzymes by marine pelagic fungal strains.

Fungi are ubiquitous organisms that secrete different enzymes to cleave large molecules into smaller ones so that can then be assimilated. Recent studies suggest that fungi are also present in the oceanic water column harboring the enzymatic repertoire necessary to cleave carbohydrates and proteins. In marine prokaryotes, the cell-free fraction is an important contributor to the oceanic extracellular enzymatic activities (EEAs), but the release of cell-free enzymes by marine fungi remains unknown. Here, to study the cell-free enzymatic activities of marine fungi and the potential influence of salinity on them, five strains of marine fungi that belong to the most abundant pelagic phyla (Ascomycota and Basidiomycota), were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). The biomass was separated from the medium by filtration (0.2 µm), and the filtrate was used to perform fluorogenic enzymatic assays with substrate analogues of carbohydrates, lipids, organic phosphorus, sulfur moieties, and proteins. Kinetic parameters such as maximum velocity (Vmax) and half-saturation constant (Km) were obtained. The species studied were able to release cell-free enzymes, and this represented up to 85.1% of the respective total EEA. However, this differed between species and enzymes, with some of the highest contributions being found in those with low total EEA, with some exceptions. This suggests that some of these contributions to the enzymatic pool might be minimal compared to those with higher total EEA. Generally, in the saline medium, the release of cell-free enzymes degrading carbohydrates was reduced compared to the non-saline medium, but those degrading lipids and sulfur moieties were increased. For the remaining substrates, there was not a clear influence of the salinity. Taken together, our results suggest that marine fungi are potential contributors to the oceanic dissolved (i.e., cell-free) enzymatic pool. Our results also suggest that, under salinity changes, a potential effect of global warming, the hydrolysis of organic matter by marine fungal cell-free enzymes might be affected and hence, their potential contribution to the oceanic biogeochemical cycles.

Prokaryotic Life in the Deep Ocean's Water Column.

The oceanic waters below a depth of 200 m represent, in terms of volume, the largest habitat of the biosphere, harboring approximately 70% of the prokaryotic biomass in the oceanic water column. These waters are characterized by low temperature, increasing hydrostatic pressure, and decreasing organic matter supply with depth. Recent methodological advances in microbial oceanography have refined our view of the ecology of prokaryotes in the dark ocean. Here, we review the ecology of prokaryotes of the dark ocean, present data on the biomass distribution and heterotrophic and chemolithoautotrophic prokaryotic production in the major oceanic basins, and highlight the phylogenetic and functional diversity of this part of the ocean. We describe the connectivity of surface and deep-water prokaryotes and the molecular adaptations of piezophilic prokaryotes to high hydrostatic pressure. We also highlight knowledge gaps in the ecology of the dark ocean's prokaryotes and their role in the biogeochemical cycles in the largest habitat of the biosphere.

Physiological Properties of Three Pelagic Fungi Isolated from the Atlantic Ocean.

Oceanic fungi are widely understudied compared to their terrestrial counterparts. However, they have been shown to be important degraders of organic matter in the global pelagic oceans. By examining the physiological characteristics of fungi isolated from the pelagic waters of the ocean it is possible to infer specific functions of each species in the biogeochemical processes that occur in the marine ecosystem. In this study, we isolated three pelagic fungi from different stations and depths across a transect in the Atlantic Ocean. We identified two yeasts [(Scheffersomyces spartinae (Debaryomycetaceae, Saccharomycetes, Ascomycota) and Rhodotorula sphaerocarpa (Sporidiobolaceae, Microbotryomycetes, Basidiomycota)], and the hyphae-morphotype fungus Sarocladium kiliense (Hypocreales, Sordariomycetes, Ascomycota), and conducted physiological experiments to investigate their preferred carbon uptake as well as their growth patterns under different environmental conditions. Despite their taxonomic and morphological differences, all species exhibited a high tolerance towards a wide range of salinities (0-40 g/L) and temperatures (5-35 °C). Furthermore, a shared metabolic preference for oxidizing amino acids was found among all fungal isolates. Collectively, this study provides relevant information on the physiological properties of oceanic pelagic fungi, revealing a high tolerance towards salinity and temperature changes, ultimately contributing to understanding their ecology and distribution in the oceanic water column.

Viruses under the Antarctic Ice Shelf are active and potentially involved in global nutrient cycles.

Viruses play an important role in the marine ecosystem. However, our comprehension of viruses inhabiting the dark ocean, and in particular, under the Antarctic Ice Shelves, remains limited. Here, we mine single-cell genomic, transcriptomic, and metagenomic data to uncover the viral diversity, biogeography, activity, and their role as metabolic facilitators of microbes beneath the Ross Ice Shelf. This is the largest Antarctic ice shelf with a major impact on global carbon cycle. The viral community found in the cavity under the ice shelf mainly comprises endemic viruses adapted to polar and mesopelagic environments. The low abundance of genes related to lysogenic lifestyle (<3%) does not support a predominance of the Piggyback-the-Winner hypothesis, consistent with a low-productivity habitat. Our results indicate a viral community actively infecting key ammonium and sulfur-oxidizing chemolithoautotrophs (e.g. Nitrosopumilus spp, Thioglobus spp.), supporting a "kill-the-winner" dynamic. Based on genome analysis, these viruses carry specific auxiliary metabolic genes potentially involved in nitrogen, sulfur, and phosphorus acquisition. Altogether, the viruses under Antarctic ice shelves are putatively involved in programming the metabolism of ecologically relevant microbes that maintain primary production in these chemosynthetically-driven ecosystems, which have a major role in global nutrient cycles.

[Venous and cerebral sinus thrombosis in newborns and children]. / Trombosis venosa y de senos cerebrales en recién nacidos y niños.

INTRODUCTION: Cerebral venous sinus thrombosis (CVST) is a well-known, although underestimated, cause of stroke in childhood. Its diagnosis requires a high index of suspicion, a correct interpretation of neuroimaging studies and an interrelation between clinicians and radiologists. The clinical features, risk factors and neuroimaging of children under 15 years of age with CVST were analyzed. METHODS: multicenter, retrospective, descriptive, study of a consecutive series of cases of children under 15 years of age, who were admitted due to CVST between January 1st, 2010, and March 1st, 2022. RESULTS: The study included 51 patients: 39% with acute symptoms and 59% with subacute symptoms. Newborns predominantly presented encephalopathic symptoms and seizures, while children exhibited signs of intracranial hypertension (ICH). Risk factors were identified in 90% of the cases. Magnetic resonance with angiography in venous time confirmed the diagnosis in 80% of the patients, with the straight sinus being the most affected in newborns and the lateral sinus in children. Hemorrhagic complications were found in 30.5%, being more frequent in newborns. Anticoagulation was initiated in 82% without complications. Sequelae were present in 44.4% of newborns and 37.9% of children, being more frequent and severe in newborns. CONCLUSIONS: To make an early diagnosis, it is essential to consider CVST in newborns with encephalopathic symptoms and/or seizures, and in children with signs of ICH in the presence of predisposing or triggering conditions.

Introducción: La trombosis de venas y senos venosos cerebrales (TVSC) constituye una causa conocida, aunque subestimada de ictus en la infancia. Su diagnóstico requiere un alto índice de sospecha, una correcta interpretación de la neuroimagen e interrelación entre el clínico y el radiólogo. OBJETIVO: Analizar las manifestaciones clínicas, factores de riesgo y neuroimagen de recién nacidos (RN) y niños menores de 15 años con TVSC. Métodos: Estudio descriptivo, retrospectivo, multicéntrico, de una serie consecutiva de casos de menores de 15 años que ingresaron por TVSC entre el 1 de enero del 2010 y el 1 de marzo de 2022. RESULTADOS: El estudio incluyó 51 pacientes: 39% con síntomas agudos y 59% subagudos. En los RN predominaron síntomas encefalopáticos y convulsiones, mientras en los niños elementos de hipertensión endocraneana (HTEC). Se identificaron factores de riesgo en el 90% de los casos. La resonancia magnética con angiografía en tiempo venoso confirmó el diagnóstico en el 80%, siendo el seno recto el más afectado en RN y el seno lateral en niños. Se encontraron complicaciones hemorrágicas en 30.5%, siendo más frecuentes en los RN. Se inició anticoagulación en el 82% sin complicaciones. Las secuelas estuvieron presentes en 44.4% de RN y 37.9% de niños, siendo más frecuentes y graves en los RN. CONCLUSIONES: Para realizar un diagnóstico precoz es fundamental pensar en TVSC en RN con síntomas encefalopáticos y/o convulsiones y en mayores con clínica de HTEC en presencia de enfermedades predisponentes o desencadenantes.