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Importance: International guidelines lack consistency in their recommendations regarding routine imaging in the follow-up after pancreatic resection for pancreatic ductal adenocarcinoma (PDAC). Consequently, follow-up strategies differ between centers worldwide., Objective: To compare clinical outcomes, including recurrence-focused treatment and survival, in patients with PDAC recurrence who received symptomatic follow-up or routine imaging after pancreatic resection in international centers affiliated with the European-African Hepato-Pancreato-Biliary Association (E-AHPBA)., Design, Setting, and Participants: This was a prospective, international, cross-sectional study. Patients from a total of 33 E-AHPBA centers from 13 countries were included between 2020 and 2021. According to the predefined study protocol, patients who underwent PDAC resection and were diagnosed with disease recurrence were prospectively included. Patients were stratified according to postoperative follow-up strategy: symptomatic follow-up (ie, without routine imaging) or routine imaging., Exposures: Symptomatic follow-up or routine imaging in patients who underwent PDAC resection., Main Outcomes and Measures: Overall survival (OS) was estimated with Kaplan-Meier curves and compared using the log-rank test. To adjust for potential confounders, multivariable logistic regression was used to evaluate the association between follow-up strategy and recurrence-focused treatment. Multivariable Cox proportional hazard analysis was used to study the independent association between follow-up strategy and OS., Results: Overall, 333 patients (mean [SD] age, 65 [11] years; 184 male [55%]) with PDAC recurrence were included. Median (IQR) follow-up at time of analysis 2 years after inclusion of the last patient was 40 (30-58) months. Of the total cohort, 98 patients (29%) received symptomatic follow-up, and 235 patients (71%) received routine imaging. OS was 23 months (95% CI, 19-29 months) vs 28 months (95% CI, 24-30 months) in the groups who received symptomatic follow-up vs routine imaging, respectively (P = .01). Routine imaging was associated with receiving recurrence-focused treatment (adjusted odds ratio, 2.57; 95% CI, 1.22-5.41; P = .01) and prolonged OS (adjusted hazard ratio, 0.75; 95% CI, 0.56-.99; P = .04)., Conclusion and Relevance: In this international, prospective, cross-sectional study, routine follow-up imaging after pancreatic resection for PDAC was independently associated with receiving recurrence-focused treatment and prolonged OS.

In recent decades, field and semi-field studies of malaria transmission have gathered geographic-specific information about mosquito ecology, behaviour and their sensitivity to interventions. Mathematical models of malaria transmission can incorporate such data to infer the likely impact of vector control interventions and hence guide malaria control strategies in various geographies. To facilitate this process and make model predictions of intervention impact available for different geographical regions, we developed AnophelesModel. AnophelesModel is an online, open-access R package that quantifies the impact of vector control interventions depending on mosquito species and location-specific characteristics. In addition, it includes a previously published, comprehensive, curated database of field entomological data from over 50 Anopheles species, field data on mosquito and human behaviour, and estimates of vector control effectiveness. Using the input data, the package parameterizes a discrete-time, state transition model of the mosquito oviposition cycle and infers species-specific impacts of various interventions on vectorial capacity. In addition, it offers formatted outputs ready to use in downstream analyses and by other models of malaria transmission for accurate representation of the vector-specific components. Using AnophelesModel, we show how the key implications for intervention impact change for various vectors and locations. The package facilitates quantitative comparisons of likely intervention impacts in different geographical settings varying in vector compositions, and can thus guide towards more robust and efficient malaria control recommendations. The AnophelesModel R package is available under a GPL-3.0 license at https://github.com/SwissTPH/AnophelesModel., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Golumbeanu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Tumor Lysis Syndrome (TLS) is an oncologic emergency that may occur in any patient with a hematologic malignancy, even prior to initiation of chemotherapy. Spontaneous TLS massive tumor cell destruction with intracellular electrolyte release prior to the initiation of chemotherapy. Spontaneous tumor lysis syndrome is a rare presentation, mainly occurring in Acute Leukemia and non-Hodgkin Lymphoma. Chronic Myeloid Leukemia (CML) is a low-risk disease based on TLS risk stratification. To the best of our knowledge, spontaneous TLS in the chronic phase of CML successfully treated with allopurinol and aggressive hydration has yet to be reported in the literature. A case report is described regarding a 67 year old Jamaican female with a history of hypertension who presented to the emergency department with abdominal pain, nausea, and vomiting for 1 day. The patient was found to have leukocytosis to 344,000 with 4% Blasts, hyperuricemia, and acute kidney injury. A peripheral blood smear confirmed the diagnosis of CML. Bone marrow biopsy was performed with evidence of the chronic phase of CML. The patient met clinical criteria for spontaneous tumor lysis syndrome. The patient was started on aggressive intravenous hydration, allopurinol, hydroxyurea and imatinib. Creatinine and uric acid level improved on this regimen within 48 h of initiation., Competing Interests: Declaration of Competing Interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background/objectives: Pancreatic surgery may have a long-lasting effect on patients' health status and quality of life (QoL). We aim to evaluate patient-reported outcomes (PRO) 3 months after pancreatic surgery., Methods: Patients scheduled for pancreatic surgery were enrolled in a prospective trial at five German centers. Patients completed PRO questionnaires (EQ-5D-5L, EORTC QLQ-PAN26, patient-reported happiness, and HADS-D), we report the first follow-up 3 months after surgery as an interim analysis. Statistical testing was performed using R software., Results: From 2019 to 2022 203 patients were enrolled, a three-month follow-up questionnaire was available in 135 (65.5 %). 77 (57.9 %) underwent surgery for malignant disease. Patient-reported health status (EQ-5D-5L) was impaired in 4/5 dimensions (mobility, self-care, usual activities, pain, discomfort) for patients with malignant and 3/5 dimensions (mobility, self-care, usual activities) for patients with benign disease 3 months after surgery (p < 0.05). Patients with malignant disease reported an increase in depressive symptoms, patients with benign disease had a decrease in anxiety symptoms (HADS-D; depression: 5.00 vs 6.51, p = 0.002; anxiety: 8.04 vs. 6.34, p = 0.030). Regarding pancreatic-disease-specific symptoms (EORTC-QLQ-PAN26), patients with malignant disease reported increased problems with taste, weight loss, weakness in arms and legs, dry mouth, body image and troubling side effects at three months. Patients with benign disease indicated more weakness in arms and legs, troubling side effects but less future worries at three months., Conclusion: Patient-reported outcomes of patients undergoing pancreatic surgery for benign vs. malignant disease show important differences. Patients with malignant tumors report more severely decreased quality of life 3 months postoperatively than patients with benign tumors., Competing Interests: Declaration of competing interest None of the authors has a conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: Ilofotase alfa is a human recombinant alkaline phosphatase with reno-protective effects that showed improved survival and reduced Major Adverse Kidney Events by 90 days (MAKE90) in sepsis-associated acute kidney injury (SA-AKI) patients. REVIVAL, was a phase-3 trial conducted to confirm its efficacy and safety., Methods: In this international double-blinded randomized-controlled trial, SA-AKI patients were enrolled < 72 h on vasopressor and < 24 h of AKI. The primary endpoint was 28-day all-cause mortality. The main secondary endpoint was MAKE90, other secondary endpoints were (i) days alive and free of organ support through day 28, (ii) days alive and out of the intensive care unit (ICU) through day 28, and (iii) time to death through day 90. Prior to unblinding, the statistical analysis plan was amended, including an updated MAKE90 definition., Results: Six hundred fifty patients were treated and analyzed for safety; and 649 for efficacy data (ilofotase alfa n = 330; placebo n = 319). The observed mortality rates in the ilofotase alfa and placebo groups were 27.9% and 27.9% at 28 days, and 33.9% and 34.8% at 90 days. The trial was stopped for futility on the primary endpoint. The observed proportion of patients with MAKE90A and MAKE90B were 56.7% and 37.4% in the ilofotase alfa group vs. 64.6% and 42.8% in the placebo group. Median [interquartile range (IQR)] days alive and free of organ support were 17 [0-24] and 14 [0-24], number of days alive and discharged from the ICU through day 28 were 15 [0-22] and 10 [0-22] in the ilofotase alfa and placebo groups, respectively. Adverse events were reported in 67.9% and 75% patients in the ilofotase and placebo group., Conclusion: Among critically ill patients with SA-AKI, ilofotase alfa did not improve day 28 survival. There may, however, be reduced MAKE90 events. No safety concerns were identified., (© 2024. The Author(s).)

Competing Interests: The authors declare that they have no conflict of interest.

Headache is the fifth most common presenting chief complaint in emergency departments, and it is vital to quickly rule out life-threatening secondary causes. Though there are many medications, new and old, that can be used to treat primary headache, the evidence for their effectiveness can be conflicting. This review describes the pathology, workup, and treatment for migraine and other primary headaches based on the best available evidence, including novel medications, nerve blocks, and strategies for preventing postdrome recurrence. Other headache disorders, including cluster headache, medication overuse headache, and chronic migraine are also reviewed.

Purpose: Chemotherapy is pivotal in the multimodal treatment of pancreatic ductal adenocarcinoma (PDAC). Technical advances unveiled a high degree of inter- and intratumoral heterogeneity. We hypothesized that intratumoral heterogeneity (ITH) impacts response to gemcitabine treatment and demands specific targeting of resistant subclones., Methods: Using single cell-derived cell lines (SCDCLs) from the classical cell line BxPC3 and the basal-like cell line Panc-1, we addressed the effect of ITH on response to gemcitabine treatment., Results: Individual SCDCLs of both parental tumor cell populations showed considerable heterogeneity in response to gemcitabine. Unsupervised PCA including the 1,000 most variably expressed genes showed a clustering of the SCDCLs according to their respective sensitivity to gemcitabine treatment for BxPC3, while this was less clear for Panc-1. In BxPC3 SCDCLs, enriched signaling pathways EMT, TNF signaling via NfKB, and IL2STAT5 signaling correlated with more resistant behavior to gemcitabine. In Panc-1 SCDCLs MYC targets V1 and V2 as well as E2F targets were associated with stronger resistance. We used recursive feature elimination for Feature Selection in order to compute sets of proteins that showed strong association with the response to gemcitabine. The optimal protein set calculated for Panc-1 comprised fewer proteins in comparison to the protein set determined for BxPC3. Based on molecular profiles, we could show that the gemcitabine-resistant SCDCLs of both BxPC3 and Panc-1 are more sensitive to the BET inhibitor JQ1 compared to the respective gemcitabine-sensitive SCDCLs., Conclusion: Our model system of SCDCLs identified gemcitabine-resistant subclones and provides evidence for the critical role of ITH for treatment response in PDAC. We exploited molecular differences as the basis for differential response and used these for more targeted therapy of resistant subclones., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Färber, Lapshyna, Künstner, Kohl, Sauer, Bichmann, Heckelmann, Watzelt, Honselmann, Bolm, ten Winkel, Busch, Ungefroren, Keck, Gemoll, Wellner and Braun.)

Mollusks belong to the group of shellfish, which are considered to be among the elicitors of severe food allergies worldwide. In recent years, numerous PCR detection methods have been developed for other shellfish such as crustaceans. However, cephalopods and gastropods were not considered in the development of these shellfish detection systems. In this study, we have developed highly specific real-time PCR methods for the comprehensive detection of all commercially relevant cephalopod species and the gastropod families Helicidae, Buccinidae, and Muricidae in food matrices. In total, we cross-tested over 100 animal and plant species to show the specificity of our systems. The limit of detection (LOD 12 ) was set at 1 pg of cephalopod and gastropod DNA or 10 ppm (mg/kg) spiked in a vegetarian food product. The robustness of the protocol was confirmed by testing multiple parameters while cooking and autoclaving of samples ensured the practical applicability of the systems.

Background: Personal continuity - having a GP who knows their patients and keeps track of them - is an important dimension of continuity of care and is associated with lower mortality rates, higher quality of life, and reduced healthcare costs. In recent decades it has become more challenging for GPs to provide personal continuity owing to changes in society and health care., Aim: To investigate GPs' and older patients' views on personal continuity and how personal continuity can be improved., Design & Setting: Cross sectional survey study in The Netherlands., Method: A digital and postal survey was sent to 499 GPs and 1599 patients aged 65 years or older. Results were analysed using descriptive statistics for quantitative data and thematic analysis for open questions., Results: In total, 249 GPs and 582 patients completed the surveys. A large majority of GPs (92-99%) and patients (91-98%) felt it was important for patients to see their own GP for life events or psychosocial issues. GPs and patients provided suggestions on how personal continuity can be improved. The thematic analysis of these suggestions identified nine themes: 1) personal connection, 2) GP accessibility and availability, 3) communication about (dis)continuity, 4) GP responsibility, 5) triage, 6) time for the patient, 7) actions by third parties, 8) team continuity, and 9) GP vocational training., Conclusion: Both GPs and older patients still place high value on personal continuity in the context of a changing society. GPs and patients provided a wide range of suggestions for improving personal continuity. The authors will use these suggestions to develop interventions for optimising personal continuity in general practice., (Copyright © 2023, The Authors.)

The past 40 years have witnessed extensive research on fractal structure and scale-free dynamics in the brain. Although considerable progress has been made, a comprehensive picture has yet to emerge, and needs further linking to a mechanistic account of brain function. Here, we review these concepts, connecting observations across different levels of organization, from both a structural and functional perspective. We argue that, paradoxically, the level of cortical circuits is the least understood from a structural point of view and perhaps the best studied from a dynamical one. We further link observations about scale-freeness and fractality with evidence that the environment provides constraints that may explain the usefulness of fractal structure and scale-free dynamics in the brain. Moreover, we discuss evidence that behavior exhibits scale-free properties, likely emerging from similarly organized brain dynamics, enabling an organism to thrive in an environment that shares the same organizational principles. Finally, we review the sparse evidence for and try to speculate on the functional consequences of fractality and scale-freeness for brain computation. These properties may endow the brain with computational capabilities that transcend current models of neural computation and could hold the key to unraveling how the brain constructs percepts and generates behavior., (© The Author(s) 2022. Published by Oxford University Press.)

Glacier and ice sheet surfaces host diverse communities of microorganisms whose activity (or inactivity) influences biogeochemical cycles and ice melting. Supraglacial microbes endure various environmental extremes including resource scarcity, frequent temperature fluctuations above and below the freezing point of water, and high UV irradiance during summer followed by months of total darkness during winter. One strategy that enables microbial life to persist through environmental extremes is dormancy, which despite being prevalent among microbial communities in natural settings, has not been directly measured and quantified in glacier surface ecosystems. Here, we use a combination of metabarcoding and metatranscriptomic analyses, as well as cell-specific activity (BONCAT) incubations to assess the diversity and activity of microbial communities from glacial surfaces in Iceland and Greenland. We also present a new ecological model for glacier microorganisms and simulate physiological state-changes in the glacial microbial community under idealized (i) freezing, (ii) thawing, and (iii) freeze-thaw conditions. We show that a high proportion (>50%) of bacterial cells are translationally active in-situ on snow and ice surfaces, with Actinomycetota, Pseudomonadota, and Planctomycetota dominating the total and active community compositions, and that glacier microorganisms, even when frozen, could resume translational activity within 24 h after thawing. Our data suggest that glacial microorganisms respond rapidly to dynamic and changing conditions typical of their natural environment. We deduce that the biology and biogeochemistry of glacier surfaces are shaped by processes occurring over short (i.e., daily) timescales, and thus are susceptible to change following the expected alterations to the melt-regime of glaciers driven by climate change. A better understanding of the activity of microorganisms on glacier surfaces is critical in addressing the growing concern of climate change in Polar regions, as well as for their use as analogues to life in potentially habitable icy worlds., (© 2022 The Authors. Geobiology published by John Wiley & Sons Ltd.)

Introduction: In recent years, increasing options for systemic HCC treatment have become available. The development of therapy-specific prognostic scores has been encouraged. Tailoring therapy to individual patients requires prognostic scores for treatment success in addition to the Barcelona-Clinic-Liver-Cancer (BCLC) classification. We have developed and validated a prognostic score for patients treated with sorafenib., Methods: Prognostic factors identified in a multivariate analysis of 108 sorafenib patients were used to construct the Munich Sorafenib Evaluation (M-SE) score. M-SE and 9 established HCC prognostic systems were ranked according to concordance-index and AIC. External M-SE validation was performed in an independent HCC sorafenib cohort (n = 101) derived from the prospective multicenter randomized controlled SORAMIC trial., Results: Ascites (p < 0.0001; HR 2.923), tumor burden ≥50% of the liver (p = 0.0033; HR 1.946), and GOT (p < 0.0001; HR 1.716) were identified as independent prognostic parameters. All three M-SE stages were characterized by significantly different survival times (p < 0.0001). M-SE stage-A patients had a median OS of 18.7 months (95% CI: 15.6-21.8); patients in stage B and C showed a significantly shorter survival of 5.7 (2.7-8.7) and 2.0 months (1.6-2.4), respectively. M-SE (c-index 0.70; AIC 621) outperformed all other prognostic systems. External validation in a prospective cohort confirmed its superior prognostic performance., Conclusion: The M-SE score allows classification of sorafenib patients in three distinct prognostic stages. Provided that M-SE successfully passes prospective validation, it can help to predict the outcome of patients evaluated for sorafenib treatment., (© 2022 S. Karger AG, Basel.)

Blooms of pigmented algae darken the surface of glaciers and ice sheets, thereby enhancing solar energy absorption and amplifying ice and snow melt. The impacts of algal pigment and community composition on surface darkening are still poorly understood. Here, we characterise glacier ice and snow algal pigment signatures on snow and bare ice surfaces and study their role in photophysiology and energy absorption on three glaciers in Southeast Greenland. Purpurogallin and astaxanthin esters dominated the glacier ice and snow algal pigment pools (mass ratios to chlorophyll a of 32 and 56, respectively). Algal biomass and pigments impacted chromophoric dissolved organic matter concentrations. Despite the effective absorption of astaxanthin esters at wavelengths where incoming irradiance peaks, the cellular energy absorption of snow algae was 95% lower than anticipated from their pigmentation, due to pigment packaging. The energy absorption of glacier ice algae was consequently ~ 5 × higher. On bare ice, snow algae may have locally contributed up to 13% to total biological radiative forcing, despite contributing 44% to total biomass. Our results give new insights into the impact of algal community composition on bare ice energy absorption and biomass accumulation during snow melt., (© 2022. The Author(s).)

Nitrogen regulates multiple aspects of the permafrost climate feedback, including plant growth, organic matter decomposition, and the production of the potent greenhouse gas nitrous oxide. Despite its importance, current estimates of permafrost nitrogen are highly uncertain. Here, we compiled a dataset of >2000 samples to quantify nitrogen stocks in the Yedoma domain, a region with organic-rich permafrost that contains ~25% of all permafrost carbon. We estimate that the Yedoma domain contains 41.2 gigatons of nitrogen down to ~20 metre for the deepest unit, which increases the previous estimate for the entire permafrost zone by ~46%. Approximately 90% of this nitrogen (37 gigatons) is stored in permafrost and therefore currently immobile and frozen. Here, we show that of this amount, ¾ is stored >3 metre depth, but if partially mobilised by thaw, this large nitrogen pool could have continental-scale consequences for soil and aquatic biogeochemistry and global-scale consequences for the permafrost feedback., (© 2022. The Author(s).)

The physical and chemical changes that accompany permafrost thaw directly influence the microbial communities that mediate the decomposition of formerly frozen organic matter, leading to uncertainty in permafrost-climate feedbacks. Although changes to microbial metabolism and community structure are documented following thaw, the generality of post-thaw assembly patterns across permafrost soils of the world remains uncertain, limiting our ability to predict biogeochemistry and microbial community responses to climate change. Based on our review of the Arctic microbiome, permafrost microbiology, and community ecology, we propose that Assembly Theory provides a framework to better understand thaw-mediated microbiome changes and the implications for community function and climate feedbacks. This framework posits that the prevalence of deterministic or stochastic processes indicates whether the community is well-suited to thrive in changing environmental conditions. We predict that on a short timescale and following high-disturbance thaw (e.g., thermokarst), stochasticity dominates post-thaw microbiome assembly, suggesting that functional predictions will be aided by detailed information about the microbiome. At a longer timescale and lower-intensity disturbance (e.g., active layer deepening), deterministic processes likely dominate, making environmental parameters sufficient for predicting function. We propose that the contribution of stochastic and deterministic processes to post-thaw microbiome assembly depends on the characteristics of the thaw disturbance, as well as characteristics of the microbial community, such as the ecological and phylogenetic breadth of functional guilds, their functional redundancy, and biotic interactions. These propagate across space and time, potentially providing a means for predicting the microbial forcing of greenhouse gas feedbacks to global climate change., (© 2022 Her Majesty the Queen in Right of Canada. Global Change Biology published by John Wiley & Sons Ltd. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

A variety of behaviors, like spatial navigation or bodily motion, can be formulated as graph traversal problems through cognitive maps. We present a neural network model which can solve such tasks and is compatible with a broad range of empirical findings about the mammalian neocortex and hippocampus. The neurons and synaptic connections in the model represent structures that can result from self-organization into a cognitive map via Hebbian learning, i.e. into a graph in which each neuron represents a point of some abstract task-relevant manifold and the recurrent connections encode a distance metric on the manifold. Graph traversal problems are solved by wave-like activation patterns which travel through the recurrent network and guide a localized peak of activity onto a path from some starting position to a target state., (© 2022. The Author(s).)

Background: Percutaneous dilatational tracheostomy (PDT) has become the preferred method in several intensive care units (ICUs), but data on PDT performed in immunosuppressed and thrombocytopenic patients are scarce. This study aimed to analyze the feasibility of PDT in immunosuppressed and thrombocytopenic patients compared to conventional open surgical tracheostomy (OST)., Methods: We retrospectively analyzed the charts of patients who underwent PDT or OST between May 2017 and November 2020. Our outcomes were stoma site infections and bleeding complications., Results: 63 patients underwent PDT, and 21 patients underwent OST. Distribution of gender ratio, age, SAPS II, time of ventilation before tracheostomy, and preexisting hematooncological diseases was comparable between the two groups. After allogeneic stem cell transplantation (alloSCT), patients were more likely to undergo PDT than OST ( p =0.033). The PDT cohort suffered from mucositis more frequently ( p =0.043). There were no significant differences in leucocyte or platelet count on the tracheostomy day. Patients with coagulation disorders and patients under immunosuppression were distributed equally among both groups. Stoma site infection was documented in five cases in PDT and eight cases in the OST group. Moderate infections were remarkably increased in the OST group. Smears were positive in six cases in the PDT group; none of these patients had local infection signs. In the OST group, smears were positive in four cases; all had signs of a stroma site infection. Postprocedural bleedings occurred in eight cases (9.5%) and were observed significantly more often in the OST group ( p =0.001), leading to emergency surgery in one case of the OST group., Conclusion: PDT is a feasible and safe procedure in a predominantly immunosuppressed and thrombocytopenic patient cohort without an increased risk for stoma site infections or bleeding complications., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Marianne Angelberger et al.)

The preservation of nucleic acids for high-throughput sequencing is an ongoing challenge for field scientists. In particular, samples that are low biomass, or that have to be collected and preserved in logistically challenging environments (such as remote sites or during long sampling campaigns) can pose exceptional difficulties. With this work, we compare and assess the effectiveness of three preservation methods for DNA and RNA extracted from microbial communities of glacial snow and ice samples. Snow and ice samples were melted and filtered upon collection in Iceland, and filters were preserved using: (i) liquid nitrogen flash freezing, (ii) storage in RNAlater, or (iii) storage in Zymo DNA/RNA Shield. Comparative statistics covering nucleic acid recovery, sequencing library preparation, genome assembly, and taxonomic diversity were used to determine best practices for the preservation of DNA and RNA samples from these environments. Our results reveal that microbial community composition based on DNA was comparable at the class level across preservation types. Based on extracted RNA, the taxonomic composition of the active community was primarily driven by the filtered sample volume (i.e., biomass content). In low biomass samples (where <200 ml of sample volume was filtered) the taxonomic and functional signatures trend toward the composition of the control samples, while in samples where a larger volume (more biomass) was filtered our data showed comparable results independent of preservation type. Based on all comparisons our data suggests that flash freezing of filters containing low biomass is the preferred method for preserving DNA and RNA (notwithstanding the difficulties of accessing liquid nitrogen in remote glacial field sites). Generally, RNAlater and Zymo DNA/RNA Shield solutions work comparably well, especially for DNA from high biomass samples, but Zymo DNA/RNA Shield is favored due to its higher yield of preserved RNA. Biomass quantity from snow and ice samples appears to be the most important factor in regards to the collection and preservation of samples from glacial environments., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Trivedi, Keuschnig, Larose, Rissi, Mourot, Bradley, Winkel and Benning.)

Blooms of microalgae on glaciers and ice sheets are amplifying surface ice melting rates, which are already affected by climate change. Most studies on glacial microorganisms (including snow and glacier ice algae) have so far focused on the spring and summer melt season, leading to a temporal bias, and a knowledge gap in our understanding of the variations in microbial diversity, productivity, and physiology on glacier surfaces year-round. Here, we investigated the microbial communities from Icelandic glacier surface snow and bare ice habitats, with sampling spanning two consecutive years and carried out in both winter and two summer seasons. We evaluated the seasonal differences in microbial community composition using Illumina sequencing of the 16S rRNA, 18S rRNA, and ITS marker genes and correlating them with geochemical signals in the snow and ice. During summer, Chloromonas , Chlainomonas , Raphidonema , and Hydrurus dominated surface snow algal communities, while Ancylonema and Mesotaenium dominated the surface bare ice habitats. In winter, algae could not be detected, and the community composition was dominated by bacteria and fungi. The dominant bacterial taxa found in both winter and summer samples were Bacteriodetes , Actinobacteria , Alphaproteobacteria , and Gammaproteobacteria . The winter bacterial communities showed high similarities to airborne and fresh snow bacteria reported in other studies. This points toward the importance of dry and wet deposition as a wintertime source of microorganisms to the glacier surface. Winter samples were also richer in nutrients than summer samples, except for dissolved organic carbon-which was highest in summer snow and ice samples with blooming microalgae, suggesting that nutrients are accumulated during winter but primarily used by the microbial communities in the summer. Overall, our study shows that glacial snow and ice microbial communities are highly variable on a seasonal basis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Winkel, Trivedi, Mourot, Bradley, Vieth-Hillebrand and Benning.)