Plasma immune signatures can predict rejection-free survival in the first year after pediatric liver transplantation.

BACKGROUND & AIMS: After pediatric liver transplantation (pLT), children undergo life-long immunosuppression since reliable biomarkers for the assessment of rejection probability are scarce. In the multicenter (n = 7) prospective clinical cohort "ChilSFree" study, we aimed to characterize longitudinal dynamics of soluble and cellular immune mediators during the first year after pLT and identify early biomarkers associated with outcome. METHODS: Using a Luminex-based multiplex technique paired with flow cytometry, we characterized longitudinal dynamics of soluble immune mediators (SIMs, n = 50) and immune cells in the blood of 244 patients at eight visits over 1 year: before, and 7/14/21/28 days and 3/6/12 months after pLT. RESULTS: The unsupervised clustering of patients based on SIM profiles revealed six unique SIM signatures associated with clinical outcome. From three signatures linked to improved outcome, one was associated with 1-year-long rejection-free survival and stable graft function and was characterized by low levels of pro-inflammatory SIMs (CXCL8/9/10/12, CCL7, SCGF-ß, sICAM-1), and high levels of regenerative (SCF, TNF-ß) and pro-apoptotic (TRAIL) SIMs (all, p <0.001, fold change >100). Of note, this SIM signature appeared 2 weeks after pLT and remained stable over the entire year, pointing towards its potential as a novel early biomarker for minimizing or weaning immunosuppression. In the blood of these patients, a higher frequency of CD56bright natural killer cells (p <0.01), a known hallmark also associated with operationally tolerant pLT patients, was detected. The concordance of the model for prediction of rejection based on identified SIM signatures was 0.715, and 0.795, in combination with living-related transplantation as a covariate, respectively. CONCLUSIONS: SIM blood signatures may enable the non-invasive and early assessment of rejection risks in the first year after pLT, paving the way for improved clinical management. IMPACT AND IMPLICATIONS: ChilSFree represents the largest pediatric liver transplant (pLT) cohort with paired longitudinal data on soluble immune mediators (SIMs) and immune phenotyping in the first year after pLT. SIM signatures allow for the selection of rejection-free patients 2 weeks after pLT independently of patient diagnosis, sex, or age. The SIM signatures may enable the non-invasive and early assessment of rejection risks, paving the way for minimization or withdrawal of immunosuppression after pLT.

Multidisciplinary management of children with acute liver failure - Report on 104 children treated in single center.

BACKGROUND: Pediatric acute liver failure (PALF) is one of the most demanding emergencies in hepatology, intensive care, and for transplant team. This report describes the clinical pattern, diagnostic and therapeutic modalities in children with ALF considered at risk of death without liver transplantation, basing on a long-term experience of the pediatric transplant center. MATERIALS AND METHODS: Between 1990 and 2022, 104 children aged 7 days-17 years (median 8 years), with body weight 3.1 to 77 kg (median 32 kg), were qualified for LT due to ALF, and finally 81 (78%) of them were transplanted (9% of all 899 LT performed in children in the same period). RESULTS: A total of 23 children were not transplanted: 15 (14.4%) died while awaiting transplantation. In 8 (7.7%) patients liver function recovered. Before transplantation 45 (43.3%) children developed circulatory failure, in 66 (63.5%) mechanical ventilation was necessary, 18 patients presented acute kidney injury (17.3%), and encephalopathy higher than stage I was present in 60 (57.7%) patients. In 63 children, various kidney/liver assist procedures were performed: CVVHD (continuous veno-venous hemodiafiltration in 22 (21.2%) patients, albumin dialysis (MARS; molecular adsorbent recirculating system) in 39 (37.5%) patients, therapeutic plasma exchange (TPE) in 13 (12.5%) patients. Twenty (24.7%) children died after LT including 15 (18.5%) in the early posttransplant period, and 5 (6.1%) in the late follow-up. CONCLUSIONS: Treatment of children with ALF in the peritransplant period is very difficult and require an experienced, multidisciplinary team. Despite continued advances in the care of children with ALF, patient survival remains lower than for elective indications for liver transplantation, and timely qualification and transplantation still are the most important factors of survival of these children.

Classical autoimmune hepatitis and the IgG4-associated autoimmune hepatitis in paediatric patients.

The IgG4-associated autoimmune hepatitis (IgG4-AIH) is a newly proposed disease entity characterised by the accumulation of the IgG4-expressing plasma cells in the liver. Its pathophysiology and clinical significance remain unclear and have poor evidence in the paediatric population. Thus, our study aims at comparing the group of paediatric patients with classical AIH and the IgG4-AIH. We carried out a retrospective analysis of 23 children (median age 8.5 years) diagnosed with AIH, who were compared according to the presence of IgG4-positive plasma cells in the liver biopsy. IgG4-AIH was defined if 10 or more IgG4 positive plasma cells/high-power field were found in the biopsy. The presence of the IgG4 component seems to be clinically insignificant. That is why, the conventional immunosuppressive protocol should be considered the standard treatment in the case of the IgG4-associated AIH.

Progressive familial intrahepatic cholestasis type 3: Report of four clinical cases, novel ABCB4 variants and long-term follow-up.

INTRODUCTION AND OBJECTIVES: Progressive familial intrahepatic cholestasis type 3 (PFIC-3) is a rare autosomal recessive cholestatic liver disorder caused by mutations in the ABCB4 gene. The aim of this study was to present the phenotypic and genotypic spectrum of 4 Polish PFIC-3 patients diagnosed in a one-referral centre. MATERIALS AND METHODS: The study included 4 patients with cholestasis and pathogenic variants in the ABCB4 gene identified by next-generation sequencing (NGS) of a targeted-gene panel or whole exome sequencing (WES). Clinical, laboratory, histological, and molecular data were collected. RESULTS: Four patients (three males) were identified. The age at first noted clinical signs and symptoms was 6, 2.5, 14, and 2 years respectively; the mean age was 6 years. Those signs and symptoms include pruritus (2 out of 4 patients) and hepatomegaly with splenomegaly (4 out of 4 patients). The age at the time of referral to our centre was 9, 3, 15, and 2.5 years respectively, while the mean age was 7 years. Chronic cholestatic liver disease of unknown aetiology was established in all of them. The NGS analysis was performed in all patients at the last follow-up visit. Three novel variants including c.902T>A, p.Met301Lys, c.3279+1G>A, p.?, and c.3524T>A, p.Leu1175His were identified. The time from the first consultation to the final diagnosis was 14, 9, 3, and 1 year respectively; the mean was 6.8 years. A detailed follow-up was presented. CONCLUSIONS: The clinical phenotype of PFIC-3 could be variable. The clinical and biochemical diagnosis of PFIC-3 is difficult, thus the NGS study is very useful in making a proper diagnosis.

Similarities and Differences in Allocation Policies for Pediatric Liver Transplantation Across the World.

OBJECTIVES: We aimed to investigate national allocation policies for pediatric liver transplantation (LT). METHOD: A survey was prepared by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Hepatology Committee in collaboration with the North American Studies of Pediatric Liver Transplantation consortium. The survey was sent to pediatric hepatologists and transplant surgeons worldwide. National data were obtained from centrally based registries. RESULTS: Replies were obtained from 15 countries from 5 of the world continents. Overall donation rate varied between 9 and 35 per million inhabitants. The number of pediatric LTs was 4 to 9 per million inhabitants younger than 18 years for 13 of the 15 respondents. In children younger than 2 years mortality on the waiting list (WL) varied between 0 and 20%. In the same age group, there were large differences in the ratio of living donor LT to deceased donor LT and in the ratio of split liver segments to whole liver. These differences were associated with possible discrepancies in WL mortality. CONCLUSIONS: Similarities but also differences between countries were detected. The described data may be of importance when trying to reduce WL mortality in the youngest children.

Immune monitoring after pediatric liver transplantation - the prospective ChilSFree cohort study.

BACKGROUND: Although trough levels of immunosuppressive drugs are largely used to monitor immunosuppressive therapy after solid organ transplantation, there is still no established tool that allows for a validated assessment of functional degree of immunosuppression or the identification of clinically relevant over- or under-immunosuppression, depending on graft homeostasis. Reliable non-invasive markers to predict biopsy proven acute rejection (BPAR) do not exist. Literature data suggest that longitudinal measurements of immune markers might be predictive of BPAR, but data in children are scarce. We therefore propose an observational prospective cohort study focusing on immune monitoring in children after liver transplantation. We aim to describe immune function in a cohort of children before and during the first year after liver transplantation and plan to investigate how the immune function profile is associated with clinical and laboratory findings. METHODS: In an international multicenter prospective approach, children with end-stage liver disease who undergo liver transplantation are enrolled to the study and receive extensive immune monitoring before and at 1, 2, 3, 4 weeks and 3, 6, 12 months after transplantation, and whenever a clinically indicated liver biopsy is scheduled. Blood samples are analyzed for immune cell numbers and circulating levels of cytokines, chemokines and factors of angiogenesis reflecting immune cell activation. Statistical analysis will focus on the identification of trajectorial patterns of immune reactivity predictive for systemic non-inflammatory states, infectious complications or BPAR using joint modelling approaches. DISCUSSION: The ChilSFree study will help to understand the immune response after pLTx in different states of infection or rejection. It may provide insight into response mechanisms eventually facilitating immune tolerance towards the graft. Our analysis may yield an applicable immune panel for non-invasive early detection of acute cellular rejection, with the prospect of individually tailoring immunosuppressive therapy. The international collaborative set-up of this study allows for an appropriate sample size which is otherwise difficult to achieve in the field of pediatric liver transplantation.

Endoscopic treatment in biliary strictures after pediatric liver transplantation.

BACKGROUND AND AIM: The aim of the study was to assess efficacy and safety of endoscopic treatment in BS after pediatric LTx. METHODS: We retrospectively reviewed data of patients with DDA who developed BS and underwent ERCP. RESULTS: Of 189 transplanted patients with DDA, strictures developed in 30 (16%). In this subgroup, the median age at LTx was 14.7 (1.5-17.6) and follow-up period was 3.9 (1.3-11.3). ABS were in 76% and NABS in combination with ABS in 24% of patients. Overall, 95 ERCP sessions (3.0 per patient) were performed with successful outcome in 22 (73%) cases. Duration of treatment was 9.1 (1.8-24.1) months. Five patients underwent surgical revision and three patients retransplantation (10%). Risk factors of endoscopy failure were HCV or HBV infection, prolonged CIT and treatment before 2007. The most common complications after ERCP were cholangitis (8.2%) and pancreatitis (4.2%). There were worse overall prognosis and higher risk of post-ERCP complications in NABS. CONCLUSIONS: ERCP is safe and effective in the majority of patients with post-transplant duct-to-duct BS, and it is currently recommended as the first-line treatment.

Oral mucosa lesions and gingival bleeding can indicate the progression of liver disease in children and adolescents aged two to 18 years.

AIM: This study assessed correlations between systemic disturbances of paediatric chronic liver diseases (CLD) and oral symptoms in subjects aged 2-18 years. METHODS: It was carried out during outpatient appointments at the Children's Memorial Health Institute, Warsaw, Poland, from 2010 to 2015 and comprised 52 CLD patients with a mean age of 12.3 ± 4.6. We also recruited 54 generally healthy controls with a mean age of 12.0 ± 3.7 from the Department of Paediatric Dentistry at the Medical University of Warsaw. The study used various measures, including the Child-Pugh score, which assesses CLD prognosis. We also assessed the causes of liver disease and the medication taken by the patients with CLD. RESULTS: A total of 24 patients received a Child-Pugh score of seven or more points, while 28 patients were awarded five or six points. More severe cases of gingivitis and a greater prevalence of oral lesions were evident in patients suffering from liver disease. Oral candidiasis, telangiectasia, bald tongue, cracked strawberry lip, yellowish-brown gum discoloration, petechiae and gingival bleeding all correlated with the severity of liver dysfunction, coagulopathy, protein, bilirubin and creatinine levels and portal hypertension. CONCLUSION: This study found that oral lesions and gingival bleeding may indicate the progression of liver failure.

Fifteen years' experience of implantable cardioverter defibrillator in children and young adults: Mortality and complications study.

BACKGROUND: Young implantable cardioverter defibrillator (ICD) recipients have a high rate of complications, some of which seem to be underestimated. We report our clinical experience with ICD therapy in children and young adults during a 15 year follow up. METHODS: We reviewed the database of ICD recipients at the present institution and chose 73 consecutive patients who underwent implantation at age 6-21 years. We analyzed intervention rate, mortality, rate and characteristics of complications and treatment options. RESULTS: A total of 20/73 patients (27.4%) received ≥1 episode of appropriate therapy (AT) for ventricular tachycardia/ventricular fibrillation (anti-tachycardia pacing or shock) and 24/73 patients (32.8%) had one or multiple episodes of inappropriate therapy (IT). Eight patients (11%) had both interventions: AT + IT. A total of 15/73 patients (20.5%) had ventricular lead dysfunction, with 13 re-implantations (17.8%) of a new system. Four of 73 patients (5.5%) had infection: endocarditis or device pocket infection. A total of 2/73 patients (2.7%) died due to ventricular lead dysfunction, while 22/73 patients (30.1%) needed elective device replacement, five of them twice (6.8%). CONCLUSION: Endocardial ICD implantation in children and young adults is a feasible and life-saving procedure, according to the present 15 year follow up. The rate of complications including IT was high: 72.8% in the young ICD recipients. Re-implantation of a new system was often required due to ventricular lead dysfunction or infection in 25% of the patients.

Influence of Partial External Biliary Diversion on the Lipid Profile in Children With Progressive Familial Intrahepatic Cholestasis.

OBJECTIVES: The concentration of bile acids is highly increased in progressive familial intrahepatic cholestasis (PFIC). Bile acids are the end products of cholesterol metabolism, and aid in the absorption of fat-soluble vitamins and dietary fat. The aim of our study was to investigate lipid metabolism in patients with PFIC with focus on the effect of partial external biliary diversion (PEBD). METHODS: In 26 patients with PFIC, who underwent PEBD surgery at the median age of 2.2 years (range: 0.4-16.6), we analyzed the concentrations of lipids and apolipoproteins both before and 6 months after PEBD. Patients were split into 2 groups according to the outcome of surgery (either "good" or "poor"), and were analyzed separately. A "good" result following surgery was defined as complete relief from pruritus, and normalization of total bilirubin (<1.0 mg/dL) and bile acid concentration in serum (<12 µmol/L). RESULTS: We found abnormal lipid concentrations at baseline in all 26 patients: cholesterol was increased (>190 mg/dL) in 13 patients, phospholipids were increased (>250 mg/dL) in 5 patients, and triglyceride concentration was increased (>150 mg/dL) in 13 patients. After PEBD, the concentrations of plasma cholesterol, triglycerides, and phospholipids decreased significantly, whereas, ApoA-I and high-density lipoprotein cholesterol concentrations increased and the concentrations of apolipoprotein B, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol significantly decreased. PEBD had neither an effect on ApoE concentration nor on lecithin-cholesterol acyl transferase activity. In the group with a "poor" outcome report following PEBD, total serum cholesterol concentration decreased significantly, and no effect on the concentrations of triglycerides and phospholipids were observed. CONCLUSIONS: Patients with PFIC present with a high risk of lipid disturbances. PEBD has a beneficial effect on lipid profile in the majority of cases.

Successful pregnancy after ileal exclusion in progressive familial intrahepatic cholestasis type 2.

Progressive familial intrahepatic cholestasis type 2 (PFIC 2) results from mutations in ABCB11 gene coding bile salt export pump (BSEP). Medical treatment is usually unsuccessful and surgery intervention is necessary. Partial external biliary diversion (PEBD) is regarded as the first choice of surgical treatment. Ileal exclusion (IE) is an alternative operation if external stoma is not tolerated; however, a favorable outcome is uncertain. In chronic liver diseases pregnancy brings additional risk of deterioration of liver function and generally is not recommended. We present the first case report of successful pregnancy in a genetically confirmed PFIC 2 patient after surgical conversion from PEBD to IE.

The limited prognostic value of liver histology in children with biliary atresia.

UNLABELLED: Background and rationale for the study. The aim of the study was to determine the prognostic value of histopathological findings with special care to the severity of liver fibrosis at the moment of hepatoportoenterostomy (HPE) in children with biliary atresia (BA). We performed analysis of 142 wedge liver biopsies taken at the time of HPE. All patients were operated by the same surgical team between 1995 and 2007. According to the outcome 6 months after HPE patients were divided into prognostic groups: group 1-bilirubin level < 2 mg% (n = 65), group 2-bilirubin level > 2 mg% (n = 77). Liver biopsies were re-evaluated according to the extended histopathological protocol and then were compared between the prognostic groups. Survival with native liver (SNL) estimates were performed in regard to severity of liver fibrosis. RESULTS: Survival with native liver estimates after 2, 5 and 10 years in patients after successful operation were 96%, 91%, 75% vs. 30%, 11%, and 5% if operation failed (p < 0.001). There was no difference between groups in the following variables: fibrosis (p = 0.69), portal inflammation (p = 0.99), lobular inflammation (p = 0.95), cholangiolitis (p = 0.23), accumulation of bile pigments (zone 1:p = 0.49; zone 2:p = 0.51; zone 3:p = 0.48), bile plugs in canaliculi (p = 0.12), bile plugs in ducts (p = 0.32), bilirubinostasis in hepatocytes (p = 0.45), bile ductular proliferation (p = 0.59), ductal plate malformation (p = 0.12), focal necrosis (p = 0.44), giant cell transformation (p = 0.45), haematopoesis (p = 0.52), ductopenia (p = 0.46), microabscesses (p = 0.49), ballooning of hepatocytes (p = 0.08). The actuarial 5/10-year SNL was not dependent on severity of liver fibrosis (log-rank test p = 0.84). The severity of fibrosis corresponded neither with the age at HPE nor with the laboratory findings before operation but increased the risk of portal hypertension. CONCLUSION: Liver histology at the time of HPE is of limited value in prognosis making in BA.

Treatment of pruritus with Prometheus dialysis and absorption system in a patient with benign recurrent intrahepatic cholestasis.

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive liver disorder characterized by recurrent episodes of jaundice and itching. Episodes of cholestasis last variously from 1 week to several months, may start at any age and usually resolve spontaneously. No effective treatment has been found as yet. We report a case of genetically proven BRIC in a male patient who developed three episodes of pruritus and jaundice at the age of 14, 16 and 19 years. During the third episode, he did not respond to pharmacological medical therapy, and fractionated plasma separation and absorption (FPSA, Prometheus) was performed to manage intractable pruritus. The treatment immediately alleviated pruritus, lowered serum bilirubin concentration and induced sustained remission in the 5-year follow up. FPSA seems to be a safe and effective way of treatment for BRIC in patients with severe pruritus and prolonged jaundice.

Ileal exclusion in children with progressive familial intrahepatic cholestasis.

OBJECTIVES: Children with progressive familial intrahepatic cholestasis (PFIC) rarely benefit from medical treatment and most patients require surgical intervention. Partial external biliary diversion (PEBD) is presently the treatment of choice but for those who cannot benefit from PEBD, an alternative surgical procedure--ileal exclusion (IE)--was introduced. The aim of this study was to analyze our experience with IE in children with PFIC. METHODS: This procedure was performed in 9 patients (6 girls, 3 boys) at the median age of 11 years (range 8-21). In 4 children, it was the primary operation (group 1), and in 5, IE was performed after PEBD (group 2). All of the patients were screened for ABCB11 and ATP8B1 mutations, and in 3 cases, PFIC type 2 was confirmed. RESULTS: Median follow-up after IE surgery was 8.5 years (range 3-14). In group 1, 1 patient had to be converted to PEBD and the remaining 3 children experienced alleviation in pruritus and decrease in bilirubin and bile acids concentrations 2 and 5 years after IE. After 10 years, only 2 children were still accessible for follow-up. In both, pruritus varied and elevated serum bile acids were observed. Of the 5 patients who underwent IE after PEBD, 1 eventually required liver transplantation, 1 developed varying degree of pruritus, and 3 female patients, operated on because of aesthetic reasons, had excellent outcomes. CONCLUSIONS: IE is an alternative rescue option to PEBD and should be offered cautiously, only to patients who cannot benefit from PEBD.

In ovo injection of bee pollen extract on hatchability, chick quality, glycogen reserves and production performance in broiler chickens.

This study aimed to investigate the effects of in ovo injection of bee pollen (BP) extract on some hatching traits, glycogen reserves and production performance in broilers. A total of 886 eggs was randomly assigned to 5 treatments: the 0.9% NaCl diluent-injected control group, and the groups that were injected with BP extract at 3 different concentrations: BP-1.5%, BP-2.5% and BP-5.0% (7, 12 and 25 mg/egg, respectively). The last group received a carbohydrate solution (CS). At 18 d of incubation, 500 µL of each solution was injected into the air sac of each egg of the injected groups. After hatching, a total of 570 one-day-old chicks were distributed into 5 groups (in ovo injection) with 3 replicates with 38 birds. The in ovo injection of BP at a dose of 5% and CS resulted in lower hatching rates (P < 0.05) as compared with the control group. The level of glycogen in the muscle tissue of newly hatched birds was not significantly different (P > 0.05). Supplementation of embryos with BP extract also caused a significant increase in the length of chicks in the BP-1.5% group (P < 0.001). Hatched chicks from the injected eggs had a lower liver glycogen content than that of the control. Based on the results, it was concluded that high-quality day-old chicks could be obtained by in ovo injection. Supplementation of chicks with 1.5% BP extract had a beneficial effect on BW during the first rearing period and showed a hypocholesterolemic effect in young chicks. At the same time, an adverse effect of a high dose of BP (5%) and a carbohydrate solution administered in ovo on the hatchability level of chicks was shown. The implementation of the carbohydrate mixture resulted in a deterioration of biochemical indices in the plasma of newly hatched chicks, especially in the case of transaminase activity.

Sediment DNA metabarcoding and morphology provide complementary insight into macrofauna and meiobenthos response to environmental gradients in an Arctic glacial fjord.

Arctic fjords ecosystems are highly dynamic, with organisms exposed to various natural stressors along with productivity clines driven by advection of water masses from shelves. The benthic response to these environmental clines has been extensively studied using traditional, morphology-based approaches mostly focusing on macroinvertebrates. In this study we analyse the effects of glacially mediated disturbance on the biodiversity of benthic macrofauna and meiobenthos (meiofauna and Foraminifera) in a Svalbard fjord by comparing morphology and eDNA metabarcoding. Three genetic markers targeting metazoans (COI), meiofauna (18S V1V2) and Foraminifera (18S 37f) were analyzed. Univariate measures of alpha diversity and multivariate compositional dissimilarities were calculated and tested for similarities in response to environmental gradients using correlation analysis. Our study showed different taxonomic composition of morphological and molecular datasets for both macrofauna and meiobenthos. Some taxonomic groups while abundant in metabarcoding data were almost absent in morphology-based inventory and vice versa. In general, species richness and diversity measures in macrofauna morphological data were higher than in metabarcoding, and similar for the meiofauna. Both methodological approaches showed different patterns of response to the glacially mediated disturbance for the macrofauna and the meiobenthos. Macrofauna showed an evident distinction in taxonomic composition and a dramatic cline in alpha diversity indices between the outer and inner parts of fjord, while the meiobenthos showed a gradual change and more subtle responses to environmental changes along the fjord axis. The two methods can be seen as complementing rather than replacing each other. Morphological approach provides more accurate inventory of larger size species and more reliable quantitative data, while metabarcoding allows identification of inconspicuous taxa that are overlooked in morphology-based studies. As different taxa may show different sensitivities to environmental changes, both methods shall be used to monitor marine biodiversity in Arctic ecosystems and its response to dramatically changing environmental conditions.

Taxonomic and abundance biases affect the record of marine eukaryotic plankton communities in sediment DNA archives.

Environmental DNA (eDNA) preserved in marine sediments is increasingly being used to study past ecosystems. However, little is known about how accurately marine biodiversity is recorded in sediment eDNA archives, especially planktonic taxa. Here, we address this question by comparing eukaryotic diversity in 273 eDNA samples from three water depths and the surface sediments of 24 stations in the Nordic Seas. Analysis of 18S-V9 metabarcoding data reveals distinct eukaryotic assemblages between water and sediment eDNA. Only 40% of Amplicon Sequence Variants (ASVs) detected in water were also found in sediment eDNA. Remarkably, the ASVs shared between water and sediment accounted for 80% of total sequence reads suggesting that a large amount of plankton DNA is transported to the seafloor, predominantly from abundant phytoplankton taxa. However, not all plankton taxa were equally archived on the seafloor. The plankton DNA deposited in the sediments was dominated by diatoms and showed an underrepresentation of certain nano- and picoplankton taxa (Picozoa or Prymnesiophyceae). Our study offers the first insights into the patterns of plankton diversity recorded in sediment in relation to seasonality and spatial variability of environmental conditions in the Nordic Seas. Our results suggest that the genetic composition and structure of the plankton community vary considerably throughout the water column and differ from what accumulates in the sediment. Hence, the interpretation of sedimentary eDNA archives should take into account potential taxonomic and abundance biases when reconstructing past changes in marine biodiversity.

Distribution of HCV genotypes in Poland.

UNLABELLED: Available data on prevalence of HCV genotypes in Poland are insufficient. The aim of the study was the analysis of distribution of HCV genotypes in Poland over the period of recent 10 years regarding the age of patients and the regions of the country. MATERIAL AND METHODS: Analysis of HCV genotypes in Poland was carried out between 2003 and 2012, and included 14 651 patients from 22 centers where patients with chronic viral hepatitis C are diagnosed and treated. Genotypes were analyzed in age groups (< 20 years of age, 20-40 years of age, > 40 years of age) as well as in populations of HBV and HIV co-infections. RESULTS: Genotype (G) 1 infection was demonstrated in 79.4%, G2 -0.1%, G3- 13.8%, G4- 4.9%, G6-0.09% and mixed infections in 1.6%. There was no infection with genotype 5. The highest prevalence of G1 was observed in the Lódzkie voivodship (89.2%) and the Slaskie voivodship (86.7%) while the lowest one in the Warminsko-mazurskie (62.0%) and the Podlaskie voivodships (68.2%). Genotype 3 most commonly occurs in the Warminsko-mazurskie (28.1%), and the Podlaskie voivodships (23.0%) and is least common in the Malopolskie (7.9%) and the Lódzkie voivodships (9.0%). Genotype 4 is more common in the Kujawsko-pomorskie (11.7%) and the Podlaskie voivodships (8.6%) and relatively less common in the Lubelskie (1.1%) and the Lódzkie voivodships (1.8%). Prevalence of G1 infection in 2003-2004 was 72% and increased up to 85.6% in 2011-2012, that was accompanied by decrease of G3 prevalence from 17% to 8% in this period. In HBV co-infected (n = 83), G1 infection was demonstrated in 85.5%, G3 - in 7.2%, G4 -4.8%, and mixed genotypes in 6%. Among HIV co-infected (n = 391), a much lower prevalence of G1 (33.0%) and a high of G3 (40.4%) as well as G4 (24.0%) were observed. CONCLUSIONS: There is a geographic variability of HCV genotypes prevalence in Poland. Increase of HCV G1 infections and decrease of G3 and G4 were observed in the last 10 years. Genotypes G3 and G4 occur more often in HCV/HIV co-infected than in HCV mono-infected patients.

Contrasting Marine Microbial Communities of the Fram Strait with the First Confirmed Record of Cyanobacteria Prochlorococcus marinus in the Arctic Region.

The seawater microbiome is crucial in marine ecosystems because of its role in food chains and biogeochemical cycles; thus, we studied the composition of the pelagic marine microbiome collected in the upper 50 m on the opposite sides of Fram Strait: Spitsbergen and Greenland shelves. We found out that it differed significantly, with salinity being the main environmental variable responsible for these differences. The Spitsbergen shelf was dominated by Atlantic Waters, with a rather homogenous water column in terms of salinity and temperature down to 300 m; hence, the marine microbial community was also homogenous at all sampled depths (0, 25, 50 m). On the contrary, stations on the Greenland shelf were exposed to different water masses of both Arctic and Atlantic origin, which resulted in a more diverse microbial community there. Unexpectedly, for the very first time, we identified cyanobacterium Prochlorococcus marinus in Arctic waters (Spitsbergen shelf, 75-77° N). Till now, the distribution of this cyanobacteria in oceans has been described only between 40° N and 40° S. Considering the accelerated rate of climate warming in the Arctic, our results indicated that the seawater microbiome can be viewed as an amplifier of global change and that the Atlantification is in progress.

Metabarcoding reveals high diversity of benthic foraminifera linked to water masses circulation at coastal Svalbard.

Arctic marine biodiversity is undergoing rapid changes due to global warming and modifications of oceanic water masses circulation. These changes have been demonstrated in the case of mega- and macrofauna, but much less is known about their impact on the biodiversity of smaller size organisms, such as foraminifera that represent a main component of meiofauna in the Arctic. Several studies analyzed the distribution and diversity of Arctic foraminifera. However, all these studies are based exclusively on the morphological identification of specimens sorted from sediment samples. Here, we present the first assessment of Arctic foraminifera diversity based on metabarcoding of sediment DNA samples collected in fjords and open sea areas in the Svalbard Archipelago. We obtained a total of 5,968,786 reads that represented 1384 amplicon sequence variants (ASVs). More than half of the ASVs (51.7%) could not be assigned to any group in the reference database suggesting a high genetic novelty of Svalbard foraminifera. The sieved and unsieved samples resolved comparable communities, sharing 1023 ASVs, comprising over 97% of reads. Our analyses show that the foraminiferal assemblage differs between the localities, with communities distinctly separated between fjord and open sea stations. Each locality was characterized by a specific assemblage, with only a small overlap in the case of open sea areas. Our study demonstrates a clear pattern of the influence of water masses on the structure of foraminiferal communities. The stations situated on the western coast of Svalbard that are strongly influenced by warm and salty Atlantic water (AW) are characterized by much higher diversity than stations in the northern and eastern part, where the impact of AW is less pronounced. This high diversity and specificity of Svalbard foraminifera associated with water mass distribution indicate that the foraminiferal metabarcoding data can be very useful for inferring present and past environmental conditions in the Arctic.