Genomic full-length sequence of the HLA-B*40:86 allele identified in a Chinese individual.

HLA-B*40:86 differs from B*40:06:01:03 by a single nucleotide exchange in exon 3.

Association of HLA-E single nucleotide polymorphisms with human myeloid leukemia.

Single nucleotide polymorphisms (SNPs) of HLA-E are related to the occurrence of many diseases, but their functions remain unclear. In this study, the function of SNPs at HLA-E rs76971248 and rs1264457 on the myeloid leukemia cells was analyzed by a progressive procedure, included genotyping, mRNA transcription, regulatory element, protein expression, and anti-tumor effect. The frequencies of rs76971248 G and rs1264457 G were found higher in myeloid leukemia patients than those in healthy blood donors (p < 0.05). For myeloid leukemia, rs76971248 T was protective, while rs1264457 G was susceptible. We also found that rs76971248 affected HLA-E mRNA transcription and membrane HLA-E (mHLA-E) expression in K562 cells through differently binding to transcription factor HOXA5 (p < 0.0001), while rs1264457 affected mHLA-E expression by changing mRNA transcription and an encoding amino acid (p < 0.01). In contrast, the expression of soluble HLA-E (sHLA-E) was not influenced by both rs1264457 and rs76971248. The higher HLA-E expression was detected among myeloid leukemia patients, and the K562 cells with higher HLA-E molecules played a significant inhibitory effect on the killing activity of NK-92MI cells (p < 0.05). In conclusion, the higher HLA-E expression of myeloid leukemia cells is promoted by rs76971248 G and rs1264457 G, which helps escape from NK-92MI cells' killing.

Strong linkage between benthic oxygen uptake and bacterial tetraether lipids in deep-sea trench regions.

Oxygen in marine sediments regulates many key biogeochemical processes, playing a crucial role in shaping Earth's climate and benthic ecosystems. In this context, branched glycerol dialkyl glycerol tetraethers (brGDGTs), essential biomarkers in paleoenvironmental research, exhibit an as-yet-unresolved association with sediment oxygen conditions. Here, we investigated brGDGTs in sediments from three deep-sea regions (4045 to 10,100 m water depth) dominated by three respective trench systems and integrated the results with in situ oxygen microprofile data. Our results demonstrate robust correlations between diffusive oxygen uptake (DOU) obtained from microprofiles and brGDGT methylation and isomerization degrees, indicating their primary production within sediments and their strong linkage with microbial diagenetic activity. We establish a quantitative relationship between the Isomerization and Methylation index of Branched Tetraethers (IMBT) and DOU, suggesting its potential validity across deep-sea environments. Increased brGDGT methylation and isomerization likely enhance the fitness of source organisms in deep-sea habitats. Our study positions brGDGTs as a promising tool for quantifying benthic DOU in deep-sea settings, where DOU is a key metric for assessing sedimentary organic carbon degradation and microbial activity.

[Establish a Graded Method to Avoid HLA Class I Antibodies Corresponding Antigen and Combining HLAMatchmaker Application in Improving the CCI Value after Platelet Transfusion for Patients with IPTR].

OBJECTIVE: To establish a graded method to avoid mean fluorescence intensity (MFI) threshold of HLA Class I antibodies corresponding antigen, and the HLAMatchmaker program has been used to select the minimum mismatch value of donor-patient epitopes. Evaluate the application value of combining both methods in selecting HLA compatible platelets (PTL) for patients with immune platelet transfusion failure (IPTR) in improving platelet the corrected count increment (CCI). METHODS: A total 7 807 PLT cross-matching compatible were performed by the solid-phase red cell adherence (SPRCA) method for 51 IPTR patients. The Luminex single antigen flow cytometry was used to detect HLA Class I antibodies in patients, and detected the MFI value for different specificity antigens of HLA Class I antibodies, was graded into strong positive group (MFI>4 000, level 1), medium positive group (1 000< MFI≤4 000, 2), weak positive group (500< MFI≤1 000, 3), and one negative control group (MFI≤500). The results of 7 807 SPRCA their negative/positive reaction wells were enrolled and statistically analyzed in different grades and the four groups, the statistical differences between the four groups were compared. Multiple applications for the select HLA Class I compatible donor events were made for patients in two cases, and HLAMatchmaker program was used to calculate the number of HLA Class I epitopes mismatches between the donors and patients. The donor with the minimum number of epitopes mismatches was selected, while avoiding the corresponding antigens of HLA Class I antibodies in levels 1 and 2, the provision of HLA compatible platelets for IPTR. After the transfusions, the CCI value of the platelet transfusion efficacy evaluation index was calculated, and the clinical evaluation of the transfusion effect was obtained through statistical analysis. RESULTS: There were statistically significant differences in the positive results of SPRCA immunoassay among the strong positive group, medium positive group, and weak positive group of 51 IPTR patients with different specific of HLA -I class antibodies and corresponding antigens(all P <0.001). The positive results showed a range from high to low, with strong positive group>medium positive group>weak positive group. There were a statistical difference among between the strongly positive or moderately positive groups and the negative control group(P <0.001). There was no statistical difference between the weakly positive group and the negative control group(P >0.05). The strong positive group was set as the corresponding specific HLA Class I site corresponding antigen grade 1 avoidance threshold, the medium positive group as the grade 2 avoidance thresholds, and the weak positive group as the grade 3 avoidance threshold. In the case of donor platelet shortage, it is not necessary to avoid the weak positive group. Avoiding the strategy of donor antigens and HLAMatchmaker program scores ≤7 corresponding to HLA Class I antibodies of levels 1 and 2, with CCI values>4.5×109/L within 24 hours, can obtain effective clinical platelet transfusion conclusions. CONCLUSION: When selecting HLA Class I compatible donors for IPTR patients, the grading avoids HLA Class I antibodies corresponding to donor antigens, and the donor selection strategy with the minimum scores of HLAMatchmaker program is comprehensively selected. The negative result confirmed by platelet cross-matching experiments has certain practical application value for improving platelet count in IPTR patients.

Discovery of the novel HLA-A*11:452N allele by next-generation sequencing in a Chinese individual.

HLA-A*11:452N differs from A*11:01:01:01 by a single nucleotide exchange in exon 1.

Genome-based reclassification of Deinococcus saudiensis Hussain et al. 2016 as a later heterotypic synonym of Deinococcus soli Cha et al. 2014.

Deinococcus saudiensis YIM F302T was compared with Deinococcus soli N5T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of D. saudiensis YIM F302T showed high similarity (99.9 %) to that of D. soli N5T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Deinococcus. A draft genomic comparison between the two strains revealed average nucleotide identity values of 96.8-97.9 % and a digital DNA-DNA hybridization estimate of 80.7±1.9 %, strongly indicating that the two strains represented a single species. Based on the combined phylogenetic, genomic and phenotypic characterization presented here, we propose D. saudiensis as a later heterotypic synonym of D. soli N5T.

Genomic sequence of the novel HLA-A*26:206:02N allele, identified in a patient with hepatitis B infection.

HLA-A*26:206:02N differs from A*26:01:01:01 by a single nucleotide exchange in exon 3.

Development of a high-resolution mass-spectrometry-based method and software for human leukocyte antigen typing.

Introduction: The human leukocyte antigen (HLA) system plays a critical role in the human immune system and is strongly associated with immune recognition and rejection in organ transplantation. HLA typing method has been extensively studied to increase the success rates of clinical organ transplantation. However, while polymerase chain reaction sequence-based typing (PCR-SBT) remains the gold standard, cis/trans ambiguity and nucleotide sequencing signal overlay during heterozygous typing present a problem. The high cost and low processing speed of Next Generation Sequencing (NGS) also render this approach inadequate for HLA typing. Methods and materials: To address these limitations of the current HLA typing methods, we developed a novel typing technology based on nucleic acid mass spectrometry (MS) of HLA. Our method takes advantage of the high-resolution mass analysis function of MS and HLAMSTTs (HLA MS Typing Tags, some short fragment PCR amplification target products) with precise primer combinations. Results: We correctly typed HLA by measuring the molecular weights of HLAMSTTs with single nucleotide polymorphisms (SNPs). In addition, we developed a supporting HLA MS typing software to design PCR primers, construct the MS database, and select the best-matching HLA typing results. With this new method, we typed 16 HLA-DQA1 samples, including 6 homozygotes and 10 heterozygotes. The MS typing results were validated by PCR-SBT. Discussion: The MS HLA typing method is rapid, efficient, accurate, and readily applicable to typing of homozygous and heterozygous samples.

Molecular evidence for the production of labile, sulfur-bearing dissolved organic matter in the seep sediments of the South China Sea.

Cold seeps with methane-rich fluids leaking out of the seafloor usually support massive biomass of chemosynthetic organisms and associated fauna. A substantial amount of methane is converted to dissolved inorganic carbon by microbial metabolism, and this process also releases dissolved organic matter (DOM) into pore water. Here, pore water samples from "Haima cold seeps" sediments and the non-seep reference sediments in the northern South China Sea were analyzed for optical properties and molecular compositions of pore water DOM. Our results showed that the relative abundance of protein-like DOM, H/Cwa and molecular lability boundary percentage (MLBL%) in the seep sediments were significantly higher than those in the reference sediments, indicating that more labile DOM related to unsaturated aliphatic compounds is produced in the seep sediments. Spearman's correlation of the fluoresce and molecular data suggested that the humic-like components (C1 and C2) mainly constituted the refractory compounds (CRAM, highly unsaturated and aromatics compounds). In contrast, the protein-like component (C3) had high H/C ratios featuring high degree of DOM lability. The amount of S-containing formulas (CHOS and CHONS) was greatly elevated in the seep sediments, likely caused by abiotic and biotic sulfurization of DOM in the sulfidic environment. Although the abiotic sulfurization was proposed to have a stabilizing effect on organic matter, our results implied that the biotic sulfurization in the cold seep sediments would increase DOM lability. Overall, the labile DOM accumulated in the seep sediments is closely linked to methane oxidation, which not only support heterotrophic communities and but also likely have an impact on carbon and sulfur cycling in the sediments and the ocean.

Demographic Factors Among HIV Confirmed Blood Donors from 2013 to 2021 in Shenzhen.

Background: New HIV (Human immune deficiency virus) infections are continuously increasing in China and it remains a huge challenge to blood donation. As access to health services has affected by COVID-19 (Corona virus disease 2019) pandemic, a drop in new diagnoses (especially HIV) was observed worldwide. Methods: During 2013-2021, 735,247 specimens from unpaid blood donors collected by Shenzhen Blood Center underwent ELISA (Enzyme -linked immunosorbent assay) and NAT (Nucleic acid test). Samples with reactivity results were sent to the Shenzhen Center for Disease Control and Prevention for WB (Western blot). All data were statistically analyzed by the Chi-Square test. Results: From 2013 to 2021, the prevalence of HIV among male blood donors was higher than in females (P < 0.01). During the COVID-19 pandemic, the prevalence of HIV among repeat blood donors decreased significantly compared to 2019 (P < 0.05), and the characteristics of blood donors changed in 2020 compared to 2019 and 2021. Conclusion: The high proportion of female blood donors would help prevent HIV from getting into the blood supply. The COVID-19 pandemic affected the demographics of blood donors as well as the prevalence of HIV among repeat blood donors. An increased number of repeat blood donors can help decrease the risk of HIV transfusion transmission during the epidemic.

Pseudomonas marianensis sp. nov., a marine bacterium isolated from deep-sea sediments of the Mariana Trench.

A novel marine Gram-stain-negative, aerobic, rod-shaped bacterium, designated as strain PS1T, was isolated from the deep-sea sediments of the Mariana Trench and characterized phylogenetically and phenotypically. Bacterial optimal growth occurred at 35 °C (ranging 10-45 °C), pH 6 (ranging pH 5-10) and with 11% (w/v) NaCl (ranging 0-17%). The 16S rRNA gene sequence similarity results revealed that strain PS1T was most closely related to Pseudomonas stutzeri ATCC 17588T, Pseudomonas nitrititolerans GL14T, Pseudomonas zhaodongensis NEAU-ST5-21T, Pseudomonas xanthomarina DSM 18231T and Pseudomonas kunmingensis HL22-2T with 98.3-98.7%. The digital DNA-DNA hybridization values and the average nucleotide identity between strain PS1T and the reference strains were 20.4-40.1% and 78.7-79.4%, respectively. The major respiratory quinone is ubiquinone Q-9. The major polar lipids were phosphatidylethanolamine, diphosphatidyglycerol, phosphatidylglycerol, phosphatidylcholine, aminoglycolipid, two unidentified glycolipids and one unidentified lipid. The predominant cellular fatty acids of strain PS1T were summed feature 8 (C18:1ω7c and/or C18:1ω6c), summed feature 3 (C16:1ω7c and/or C16:1ω6c), C16:0 and cyclo-C19:0 ω8c. The G + C content of the genomic DNA was 63.0%. The combined genotypic and phenotypic data indicated that strain PS1T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas marianensis sp. nov. is proposed, with the type strain PS1T (= DSM 112238T = MCCC 1K05112T).

[Establishment of sequence-based typing assay for KIR2DS4 gene and identification of a new allele KIR2DS4*016].

OBJECTIVE: To establish a reliable sequence-based typing method for KIR2DS4 and study its allele polymorphism in Chinese Han population. METHODS: Using PCR-SSP method to detect the positive or negative of KIR2DS4 gene in 222 random Chinese Han individuals, and then using the method of high fidelity and long-fragment PCR-SBT to amplify, sequence and genotype the exons 4 and 5 of KIR2DS4 positive individuals. RESULTS: We successfully amplified the fragment with 3.2 kb length contains exons 4 and 5 of KIR2DS4 and detected the KIR2DS4 allele frequency in Chinese Han population. 209 KIR2DS4 positive individuals were detected, and the positive rate is 94.1%. By sequence-based typing, we identified 12 genotypes and 7 alleles of KIR2DS4. The 6 known alleles and their detection frequency is as follows: KIR2DS4* 00101/011 (180, 81.1%), KIR2DS4* 010 (53, 23.9%), KIR2DS4* 004 (34, 15.3%), KIR2DS4* 003 (15 and 6.8%), KIR2DS4* 006 (2, 0.9%) and KIR2DS4* 015 (1, 0.5%). In this study, we found a new allele, KIR2DS4* 016, with the difference in exon 5 comparing its most similar allele KIR2DS4* 010. In the exon 5 of KIR2DS4* 010, there is a 22bp-deletion, while the exon 5 of KIR2DS4* 016 is normal. This is not a rare allele because it was detected 3 times in studied population and with the frequency of 1.4%. The sequence of the new allele sequence has been submitted to GenBank (accession no.: KC414890) and the IPD -KIR database (submission no.: IWS40001804), and was nominated by WHO nomenclature committee for HLA system. CONCLUSION: In this study, a sequence-based typing method for KIR2DS4 was established, and the polymorphism data of KIR2DS4 in Chinese Han population was enriched by studying the allele polymorphism and new allele.

[Molecular polymorphism Analysis on CD36 Deficiency among Platelet Blood Donors in Shenzhen].

OBJECTIVE: To analyze the molecular polymorphisms of CD36 among 58 blood donors with CD36 deficiency and compare with CD36 positive controls. METHODS: A total of 58 donors with CD36 deficiency during a screening conducted in the laboratory from September 2019 to December 2020 were enrolled as the test group, including 39 males and 19 females, while 120 platelet donors with CD36 positive were randomly selected as the controls, including 76 males and 44 females. All of the subjects were Han nationality. The PCR-SBT method was used to detect coding region of CD36 gene, and molecular mutations were compared with those CD36 positive controls. RESULTS: Among the 58 donors with CD36 deficiency, mutations appears in 32 individuals. The detection rate for type I was 71.43% (5/7), and type II was 51.92% (27/52), while among the 120 controls, mutations appears in 12 donors (10%). In the CD36 antigen-deficient donors, 16 variations were found, in which 329-330 del AC with the highest frequency accounted for 20.69%, followed by 1228-1239 del ATTGTGCCTATT(15.52%) and 1156 C>T(10.34%). Two variations, 198-205 del GATCTTTG and 220 C>T, led to premature termination of translation; four mutations, 329-330 del AC, 560 ins T, 1011-1049 39bp dupl and 1343-1344 ins TCTT, caused translation frame shift; 1228-1239 del ATTGTGCCTATT led to deletion of four amino acids (Ile-Val-Pro-Ile) at sites 410-413 of the peptide chain. The 1140 T>A and 1275 G>A were synonymous mutations, and the other 7 mutations resulted in the substitution of single nucleotide. The platelet expression in the donors of CD36 positive with 329-330 del AC or 1228-1239 del ATTGTGCCTATT mutation (heterozygote) was lower than those CD36 positive individuals without mutations (homozygote). CONCLUSION: Multiple gene mutations in the CD36 coding region may cause CD36 deficiency, and the heterozygous individuals with mutations may lead to CD36 antigen reduction or deletion. Mutation is not detected in 44.83% of CD36 deficient individuals, there may be some other reasons for the CD36 antigen deficiency.

[Study on the Relationship between the Level of Soluble HLA-E Molecules in Plasma and Gene Polymorphism and Leukemia].

OBJECTIVE: To explore the relationship between the level of soluble HLA-E (sHLA-E) molecules in plasma and gene polymorphism and leukemia in Shenzhen of China. METHODS: Enzyme-linked immunosorbent assay was used to detect sHLA-E level in plasma of 103 leukemia patients and 113 healthy blood donors. PCR-SBT was used to identify the HLA-E genotype of 73 leukemia patients and 76 healthy blood donors. RESULTS: The level of plasma sHLA-E of 103 leukemia patients was significantly higher than that of 113 healthy blood donors (P<0.001); And the level of plasma sHLA-E in 77 myeloid leukemia patients was also significantly higher (P<0.001). The percentage of patients with plasma sHLA-E concentration of 0-199 ng/ml in leukemia and myeloid leukemia patients was 37.86% and 32.47%, respectively, which was significantly lower than 53.98% of healthy donors, the difference was statistically significant (P<0.05, P<0.01); While, when the plasma sHLA-E concentration was more than 400 ng/ml, the percentage was 33.01% and 36.36%, respectively, which was significantly higher than 13.28% of healthy donors, the difference was also statistically significant (P=0.001, P<0.001). There was no significant difference in the level of plasma sHLA-E among different HLA-E genotypes (P>0.05), whether healthy blood donors or leukemia patients. CONCLUSION: The level of plasma sHLA-E in patients with leukemia (especially myeloid leukemia) is significantly higher than that of healthy blood donors, but different HLA-E genotypes do not affect the level of plasma sHLA-E. A cut-off value for the concentration of plasma sHLA-E (recommended risk value >400 ng/ml) can be set to assess the risk of certain pre-leukemia patients.

Establishment of Rapid Detection Methods for rs76971248 Related to Leukemia.

Background: The HLA-E gene is a member of the HLA-I gene family. Its genetic polymorphism is regarded as associated with numerous diseases. Establishing a rapid and accurate detection method of disease-related SNP sites in HLA-E is particularly important. Methods: Blood samples from 226 healthy blood donors and 228 leukemia patients were collected, and DNA was extracted. Three typing methods based on PCR-sequence-based typing, TaqMan genotyping, and high-resolution melting curve were established to identify rs76971248 (G>T). The Chi-square test was used for statistical analysis by SPSS. Results: Three methods based on PCR-SBT, TaqMan genotyping, and HRM were all able to identify rs76971248. The software for analyzing the results of HLA-E sequencing was easy to use, and the results were accurate. The frequency of rs76971248 in different types of leukemia patients was significantly lower than that in healthy blood donors (p < 0.05). And the frequency of the G/G genotype in leukemia patients was significantly higher than that in healthy blood donors (p < 0.05). Conclusions: For the screening of known SNP sites in large-scale populations, among the three methods, the TaqMan genotyping method had the advantage of shortest time consumption, simplest operation, and greatest specificity, which was the most appropriate method for this experiment. The analysis software for HLA-E gene sequencing needed to be further optimized. rs76971248 had a protective effect against leukemia. And the G/G genotype was a risk factor for leukemia.

Characterization of alternatively spliced transcript variants of glycophorin A and glycophorin B genes in Chinese blood donors.

BACKGROUND AND OBJECTIVES: The molecular basis of MNS blood group variants is not fully clear yet. In this study, we have characterized mRNA variants of GYPA and GYPB genes to reveal whether alternative RNA splicing may cause antigenic diversity of the MNS system. MATERIALS AND METHODS: Total RNA was extracted from peripheral blood of Chinese blood donors and full-length cDNA products were generated. A nested polymerase chain reaction (PCR)-based method was established for fragment amplification and Sanger sequencing. Resulted full-length mRNA sequences were aligned with GYPA or GYPB genomic sequences respectively for exon identification. Amino acid (AA) sequences of GPA and GPB proteins were extrapolated and GYPA-EGFP, GYPB-EGFP fusion genes were generated to monitor subcellular distribution of the encoded glycophorin (GP) proteins. RESULTS: Totally 10 blood samples were analysed. GYPB mRNAs of all the subjects demonstrated frequent exon insertion or deletion whereas this kind of variation was only observed in 3 of 10 GYPA mRNA samples. None of the reported Miltenberger hybrids was detected in any of the mRNA samples. The alternative splicing resulted in changes of AA sequences in N-terminal domains where the MNS antigenic motifs resided; however, subcellular localizations of GP-EGFP fusion proteins showed that the above-mentioned AA changes did not affect cell surface distribution of the encoded GP proteins. CONCLUSIONS: Alternative RNA splicing may influence the antigenic features of GP proteins but not their cell surface distribution. Therefore, GYPA and GYPB mRNA characterization might be an invaluable supplement to serological phenotyping and DNA-based genotyping in MNS blood grouping.

Correlation of Human Leukocyte Antigen-E Genomic Polymorphism with Leukemia and Functional Study of Human Leukocyte Antigen-E Different Type Promoters.

Human leukocyte antigen (HLA)-E is one of the least polymorphic nonclassical major histocompatibility complex (MHC) I genes; its nucleotide variability can affect immune response. In this study, we assess the correlation between HLA-E polymorphism and leukemia and further study the transcriptional activity of promoter variation at nucleotide position-26. A total of 142 healthy blood donors and 111 leukemia patients were collected. The genomic sequence of HLA-E was amplified by high-fidelity reaction system and identified by Sanger and cloning sequencing. The dual luciferase reporter gene assay was used to detect the transcription activity of promoter variation at nucleotide position-26. In the HLA-E genomic sequence results, a total of 16 alleles and 32 genotypes were detected; the HLA-E*01:01:01:06 allele had a significantly lower frequency in leukemia patients than in healthy participants (p = 0.026 < 0.05). And the HLA-E*01:03:02:01, *01:03:02:01 genotype showed the greatest difference in frequency between the two groups of participants (p = 0.028 < 0.05). Eight HLA-E alleles were first reported worldwide in Chinese individuals. The results of the dual luciferase reporter gene experiment showed that the transcription activity of the mutant-type promoter (HLA-E*01:01:01:06 with "T" allele at nucleotide position-26) was significantly lower compared with the wild-type promoter (HLA-E*01:01:01:01 with "G" allele at nucleotide position-26) (p = 0.0242 < 0.05). HLA-E*01:01:01:06 allele has a protective effect against leukemia through decreasing transcription activity by "T" variation at nucleotide position-26.

Muricauda abyssi sp. nov., a marine bacterium isolated from deep seawater of the Mariana Trench.

A Gram-stain-negative, non-motile and rod-shaped bacterium, designated as strain W52T, was isolated from deep seawater of the Mariana Trench and characterized phylogenetically and phenotypically. The strain could grow at 10-47 °C (optimum 32 °C), at pH 5.0-8.0 (optimum 6.0) and with 0-9% NaCl (optimum 3 %, w/v). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that W52T was related to members of the genus Muricauda and shared the highest identity with Muricauda oceani 501str8T (99.0 %), followed by Muricauda aquimarina JCM 11811T, Muricauda ruestringensis DSM 13258T, Muricauda oceanensis 40DY170T, Muricauda beolgyonensis KCTC 23501T and Muricauda zhangzhouensis 12C25T with 97.0-98.8 % sequence similarity. 16S rRNA gene sequence identities between W52T and other members of the genus Muricauda were below 97.0 %. The major respiratory quinone was MK-6. The polar lipids were phosphatidylethanolamine (PE), one unidentified aminolipid and three unidentified lipids. The strain had iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1G as the major fatty acids. The G+C content of the genomic DNA was 41.7 %. The combined genotypic and phenotypic data indicated that strain W52T represents a novel species of the genus Muricauda, for which the name Muricauda abyssi sp. nov. is proposed, with the type strain W52T (=MCCC 1K05111T= KCTC 82315T).

Substantial accumulation of mercury in the deepest parts of the ocean and implications for the environmental mercury cycle.

Anthropogenic activities have led to widespread contamination with mercury (Hg), a potent neurotoxin that bioaccumulates through food webs. Recent models estimated that, presently, 200 to 600 t of Hg is sequestered annually in deep-sea sediments, approximately doubling since industrialization. However, most studies did not extend to the hadal zone (6,000- to 11,000-m depth), the deepest ocean realm. Here, we report on measurements of Hg and related parameters in sediment cores from four trench regions (1,560 to 10,840 m), showing that the world's deepest ocean realm is accumulating Hg at remarkably high rates (depth-integrated minimum-maximum: 24 to 220 µg ⋅ m-2 ⋅ y-1) greater than the global deep-sea average by a factor of up to 400, with most Hg in these trenches being derived from the surface ocean. Furthermore, vertical profiles of Hg concentrations in trench cores show notable increasing trends from pre-1900 [average 51 ± 14 (1σ) ng ⋅ g-1] to post-1950 (81 ± 32 ng ⋅ g-1). This increase cannot be explained by changes in the delivery rate of organic carbon alone but also need increasing Hg delivery from anthropogenic sources. This evidence, along with recent findings on the high abundance of methylmercury in hadal biota [R. Sun et al, Nat. Commun. 11, 3389 (2020); J. D. Blum et al, Proc. Natl. Acad. Sci. U. S. A. 117, 29292-29298 (2020)], leads us to propose that hadal trenches are a large marine sink for Hg and may play an important role in the regulation of the global biogeochemical cycle of Hg.