RESUMO
BACKGROUND: Gene variants are responsible for more than half of hearing loss, particularly in nonsyndromic hearing loss (NSHL). The most common pathogenic variant in SLC26A4 gene found in East Asian populations is c.919-2A > G followed by c.2168A > G (p.H723R). This study was to evaluate their variant frequencies in patients with NSHL from special education schools in nine different areas of Southwest China's Yunnan. METHODS: We performed molecular characterization by PCR-products directly Sanger sequencing of the SLC26A4 c.919-2AG and c.2168 A > G variants in 1167 patients with NSHL including 533 Han Chinese and 634 ethnic minorities. RESULTS: The SLC26A4 c.919-2A > G variant was discovered in 8 patients with a homozygous state (0.69%) and twenty-five heterozygous (2.14%) in 1167 patients with NSHL. The total carrier rate of the c.919-2A > G variant was found in Han Chinese patients with 4.50% and ethnic minority patients with 1.42%. A significant difference existed between the two groups (P < 0.05). The c.919-2A > G allele variant frequency was ranged from 3.93% in Kunming to zero in Lincang and Nvjiang areas of Yunnan. We further detected the SLC26A4 c.2168 A > G variant in this cohort with one homozygotes (0.09%) and seven heterozygotes (0.60%), which was detected in Baoshan, Honghe, Licang and Pu`er areas. Between Han Chinese group (0.94%) and ethnic minority group (0.47%), there was no statistical significance (P > 0.05). Three Han Chinese patients (0.26%) carried compound heterozygosity for c.919-2A > G and c.2168 A > G. CONCLUSION: These data suggest that the variants in both SLC26A4 c.919-2A > G and c.2168 A > G were relatively less frequencies in this cohort compared to the average levels in most regions of China, as well as significantly lower than that in Han-Chinese patients. These results broadened Chinese population genetic information resources and provided more detailed information for regional genetic counselling for Yunnan.
Assuntos
Surdez , Etnicidade , Proteínas de Membrana Transportadoras , Humanos , Etnicidade/genética , Mutação , Proteínas de Membrana Transportadoras/genética , Grupos Minoritários , China/epidemiologia , Conexinas/genética , Transportadores de Sulfato/genéticaRESUMO
Stomata are pivotal in modulating water and carbon processes within plants. However, our understanding of the temporal dynamics of water- and carbon-related traits, as influenced by stomatal behavior, remains limited. Here, we explore how stomatal regulation behavior and water- and carbon-related traits vary with changing environments by examining the seasonal variations in these traits of the native tree species Schima superba in low subtropical China. In February, April, and July of 2022, a series of water- and carbon-related traits were measured in the leaves and stems. The results showed that S. superba exhibited isohydric behavior in February when the soil dried out and vapor pressure deficit (VPD) was lower but anisohydric behavior in April and July when the soil was wetter and VPD was higher. In February, NSC and their components increased, and a relatively large contribution of soluble sugars to the change in NSC was observed. In the branches and phloem, NSC and their components displayed a relatively high monthly variability, suggesting their role in maintaining carbon balance within the trees. Conversely, the NSC in the leaves demonstrated minimal monthly variability. The specific leaf area, as well as the concentration of nitrogen (N) and phosphorus (P) per unit mass in leaves and the cumulative stem water release, exhibited a decrease with a reduction in soil water potential. Interestingly, the hydraulic conductivity remained consistent throughout this process. Furthermore, the relatively low monthly growth rate observed in February could suggest a carbon sink limitation. In conclusion, the increased NSC and decreased water status of S. superba under relatively stressed soil conditions indicated a trade-off between water and carbon storage. Our findings enhance our comprehension of the dynamics and regulation of water and carbon status in forests, thereby advancing the development of plant carbon and water process models under climate change scenarios.
RESUMO
The complete genome sequence of a positive-sense single-stranded RNA (+ ssRNA) virus, Rhizoctonia beny-like virus 1 (RBLV1), isolated from binucleate Rhizoctonia AG-A strain A46, was determined. The RBLV1 genome is 10,280 nt in length and contains a short stretch of adenines at the 3' terminus. It contains a single open reading frame (ORF) encoding a 376.30-kDa protein with viral helicase and RNA-dependent RNA polymerase (RdRp) motifs. The encoded protein exhibited the highest sequence similarity to Rhizoctonia cerealis beny-like virus 0928-1 (RcBeLV 0928-1, 45.25%), with a sequence coverage of 63%. Phylogenetic analysis based on ORF protein sequences revealed that RBLV1 is a novel unclassified mycovirus.
Assuntos
Micovírus , Vírus de RNA , Rhizoctonia , Filogenia , Sequência de Aminoácidos , Genoma Viral , Fases de Leitura Aberta , RNA Viral/genéticaRESUMO
Intercropping is a widely used agricultural system; however, the effect of intercropping between accumulator plants on phytoextraction in heavy metal-contaminated soils remains unknown. Here, a field experiment was conducted to investigate the phytoextraction efficiency and related environmental effects of three Amaranthaceae plants (Amaranthus hypochondriacus, Celosia argentea, and Pfaffia glomerata) using mono- and intercropping models. In monocropping, the total biomass of A. hypochondriacus was only 51.2 % of that of C. argentea. Compared with monocropping, intercropping reduced the fresh weight per plant of A. hypochondriacus by 53.0 % (intercropping with C. argentea) and 40.5 % (intercropping with P. glomerata) but increased the biomass per plant of C. argentea and P. glomerata by 128.2 and 14.2 %, respectively. The Cd uptake of the three plants in the monocropping models showed the following trend: C. argentea > P. glomerata > A. hypochondriacus. Interplanting A. hypochondriacus and C. argentea further increased the phytoextraction efficiency by 361.2 % (compared with A. hypochondriacus monocropping) and 52.0 % (compared with C. argentea monocropping). Soil exchangeable Cd, Pb, Cu, Zn, K, and P, soil N-NO3- and N-NH4+, soil common bacteria and arbuscular mycorrhiza (AM) fungi, and soil total organic carbon (TOC) play key roles in Cd and Pb uptake by the three accumulator plants (p < 0.05). The biomass of common bacteria, Gm+, Gm- bacteria, fungi, AM fungi, and actinomycetes increased with the three accumulators planted in the mono- and intercropping models. Compared with C. argentea monocropping, the biomass of soil microbes in the rhizosphere soil was obviously increased in the intercropping A. hypochondriacus and C. argentea models. These results suggest that interplanting A. hypochondriacus and C. argentea can increase Cd removal efficiency from Cd-contaminated soils, and this model could be recommended to remediate Cd-contaminated soils on a field scale.
Assuntos
Amaranthus , Poluentes do Solo , Cádmio/análise , Biodegradação Ambiental , Chumbo , Poluentes do Solo/análise , Solo , PlantasRESUMO
BACKGROUND: Long-term glucocorticoid therapy may lead to osteoporosis (OP). Selenium (Se) is an essential microelement for human health and bone health. This study evaluated the association between dietary Se intake and the prevalence of OP and further explored the potential therapeutic effect of Se on glucocorticoid-induced OP (GIOP) in vivo and in vitro. METHODS: Data were collected from a population-based cross-sectional study conducted in our hospital. OP is diagnosed based on bone mineral density (BMD) measurements using compact radiographic absorptiometry. Dietary Se intake was assessed using a semi-quantitative food frequency questionnaire. The association between dietary Se intake and OP prevalence was analyzed by multivariable logistic regression. In animal experiments, male Sprague-Dawley rats were intramuscularly injected with dexamethasone (1 mg/kg) daily to induce GIOP, while different doses of Se were supplemented in rat drinking water for 60 d. BMD and biomechanical parameters of rat femur were measured. The histopathological changes of the femur were observed by HE staining, the number of osteoclasts was observed by TRAP staining, and OCN positive expression was detected by immunohistochemical staining. OPG, RANKL, Runx2, and BMP2 in rat femur were detected by Western blot. Bone turnover markers and oxidative stress markers were measured using commercial kits. MC3T3-E1 cells were induced to osteogenic differentiation, stimulated with DXM (100 µM), and/or treated with Se at different doses. Cell proliferation and apoptosis were assessed by CCK-8 and flow cytometry. ALP activity was detected by ALP staining and cell mineralization was observed by alizarin red staining. RESULTS: Participants with lower dietary Se intake had higher OP prevalence. Se supplementation improved BMD, biomechanical parameters, and histopathological changes of the femur in GIOP rats. Se supplementation also suppressed DXM-induced changes in bone turnover- and oxidative stress-related markers. Under DXM conditions, Se treatment induced MC3T3-E1 cell proliferation, ALP activity, and mineralization. CONCLUSION: Lower Dietary Se intake is associated with OP prevalence. Moreover, Se takes a position in bone protection and anti-oxidative stress in GIOP models. Therefore, Se may be a complementary potential treatment for GIOP.
Assuntos
Osteoporose , Selênio , Ratos , Masculino , Humanos , Animais , Glucocorticoides/efeitos adversos , Selênio/efeitos adversos , Osteogênese , Prevalência , Estudos Transversais , Ratos Sprague-Dawley , Osteoporose/induzido quimicamente , Osteoporose/tratamento farmacológico , Osteoporose/metabolismoRESUMO
Rhizoctonia solani is a widely disseminated phytopathogen that is found in the soil and is capable of harming many important species of crops. Here, analysis of the R. solani AG-4 HG III strain A14 led to the identification of a novel mycovirus assigned the tentative name "Rhizoctonia solani partitivirus A14" (RsPV-A14), which was subjected to sequencing and associated analyses. This approach revealed that RsPV-A14 harbored two dsRNA segments, 2022 bp (dsRNA1) and 1905 bp (dsRNA2) in length. dsRNA1 was found to contain a single open reading frame (ORF1) that codes for a 622-amino-acid protein with conserved RNA-dependent RNA polymerase (RdRp) motifs, and dsRNA2 was found to contain an ORF (ORF2) that is predicted to code for a 558-amino-acid capsid protein (CP). BLASTp analysis using the putative RdRp of RsPV-A14 showed sequence similarity to partitiviruses, including Rosellinia necatrix partitivirus 7 (50.53% identity), an unclassified partitivirus. Phylogenetic analysis based on RdRp protein sequences suggested that RsPV-A14 is a novel member of the family Partitiviridae.
Assuntos
Nucleotídeos , RNA Polimerase Dependente de RNA , Filogenia , Sequência de Bases , RNA Polimerase Dependente de RNA/genéticaRESUMO
In recent years, substantial advancements have been made in the development of enzyme-free glucose sensors utilizing pristine metal-organic frameworks (MOFs) and their combinations. This paper provides a comprehensive exploration of various MOF-based glucose sensors, encompassing monometallic MOF sensors as well as multi-metal MOF combinations. These approaches demonstrate improved glucose detection capabilities, facilitated by the augmented surface area and availability of active sites within the MOF structures. Furthermore, the paper delves into the application of MOF complexes and derivatives in enzyme-free glucose sensing. Derivatives incorporating carbon or metal components, such as carbon cloth synthesis, rGO-MOF composites, and core-shell structures incorporating noble metals, exhibit enhanced electrochemical performance. Additionally, the integration of MOFs with foams or biomolecules, such as porphyrins, enhances the electrocatalytic properties for glucose detection. Finally, this paper concludes with an outlook on the future development prospects of enzyme-free glucose MOF sensors.
Assuntos
Estruturas Metalorgânicas , Porfirinas , Carbono , Têxteis , GlucoseRESUMO
In-situ immobilization does not remove Cd from the contaminated soil. It is vital to investigate the effects of fertilizers on soil Cd mobility during remediation with amendments. In the current study, a pot experiment was conducted to investigate the effects of calcium magnesium phosphate (CMP) and calcium superphosphate (SSP) on the remediation of Cd-contaminated soil by sepiolite. We mainly focused on changes in soil Cd immobilization, plant toxicity, and soil microbial communities after applying two phosphates during Cd-contaminated soil remediation by sepiolite. The results demonstrated that sepiolite decreased Cd concentration in brown rice, straw, and roots by 32.66%, 38.89%, and 30.94%, respectively. During soil remediation by sepiolite, the Cd concentrations of brown rice and straw were not affected by CMP or SSP, except for the treatment with sepiolite plus high-dose CMP. Sepiolite significantly decreased HCl-extractable Cd and DTPA-extractable Cd by 32.21% and 10.50%, respectively. During soil remediation by sepiolite, the HCl-extractable and DTPA-extractable Cd further decreased with CMP or SSP. The decreasing amplitude with CMP was 40.57-72.60% and 7.05-14.53%, and that of SSP was 37.68-59.66% and 20.71-25.07%, respectively. The superoxide dismutase, peroxidase, catalase activities, and malondialdehyde concentration in rice roots decreased inordinately with the addition of sepiolite, CMP, and SSP, indicating that the application of sepiolite, CMP, or SSP alleviated Cd-induced rice root stress and protected rice roots from Cd toxicity. Alpha diversity estimators (including the Chao, ACE, and Shannon indices) indicated that sepiolite, CMP, or SSP applications had no adverse effects on soil bacterial richness and diversity. Hierarchical clustering analysis revealed that the two phosphate fertilizers and sepiolite were the main factors affecting changes in the bacterial communities structure. Redundancy analysis revealed that soil pH, Eh, and soil-extractable Cd were critical factors affecting the structure of the bacterial communities.
RESUMO
Understanding the variations in plant traits across elevations may provide valuable insights into the species structure and function of forests and their responses to climate change. To explore the patterns of trait variation across elevations, we analysed 14 leaf and stem traits associated with resource acquisition and stress tolerance in Schima superba Gardner & Champion, Castanopsis chinensis (Sprengel) Hance, and Pinus massoniana Lambert trees at two elevations in a subtropical forest in southern China. Wood density increased, whereas crown width, leaf water potential at 0700 hours (Ψ L-0700 ), and leaf δ 18 O decreased in high-elevation plants. Vessel diameter, daily maximum sap flux density, leaf δ 13 C, and leaf C and N concentrations per unit mass were comparable across elevations. We found species-specific variations in specific leaf area, midday leaf water potential, and leaf P concentration across elevations. Decreasing crown width with increasing elevation was associated with decreasing leaf δ 18 O and Ψ L-0700 , suggesting that higher stomatal conductance may moderate the loss of carbon assimilation. We elucidated the adaptive strategies of plants in response to environmental change, and showed that physiological traits varied in coordination with structural traits. Future studies incorporating multi-dimensional trait analyses can improve our understanding of the responses of forest ecosystems to climate change and global warming.
Assuntos
Ecossistema , Florestas , Folhas de Planta/química , Árvores/fisiologia , Madeira/químicaRESUMO
In this report, the full genome sequence of a novel mycovirus, designated as "Rhizoctonia solani partitivirus SM03" (RsPV-SM03), was determined in Rhizoctonia solani AG-4 HG III isolate SM03. RsPV-SM03 genome consists of two dsRNAs (dsRNA-1 and dsRNA-2), each of them contains one single open reading frame (ORF). ORF1 of dsRNA-1 encodes a putative RNA-dependent RNA polymerase (RdRp), while ORF2 of dsRNA-2 encodes a putative viral coat protein (CP). Phylogenetic analysis indicated that the RdRp and CP of RsPV-SM03 are closely related to those of other members of the genus Alphapartitivirus, family Partitiviridae, suggesting that RsPV-SM03 represents a novel species in the genus Alphapartitivirus.
Assuntos
Micovírus , Vírus de RNA , Sequência de Bases , Genoma Viral , Fases de Leitura Aberta , Filogenia , RNA de Cadeia Dupla , RNA Viral/genética , RhizoctoniaRESUMO
The complete nucleotide sequence of a novel mycovirus, designated as "Rhizoctonia fumigata bipartite virus 1" (RfBV1), from Rhizoctonia fumigata AG-Ba isolate C-314 Baishi was determined. The genome of RfBV1 is composed of two double-stranded RNAs (dsRNA). dsRNA-1 (2311 bp) contains one open reading frame (ORF), which codes for the putative RNA-dependent RNA polymerase (RdRp) of the virus. dsRNA-2 (1690 bp) contains one ORF, which encodes a putative protein whose function is unknown. Phylogenetic analysis indicated that the RdRp of RfBV1 clustered with several unassigned bipartite viruses belonging to the CThTV-like viruses group, but not the family Amalgaviridae or Partitiviridae. Our study suggests that RfBV1 is a novel mycovirus related to the CThTV-like viruses.
Assuntos
Micovírus , Vírus de RNA , Sequência de Bases , Genoma Viral , Fases de Leitura Aberta , Filogenia , RNA de Cadeia Dupla/genética , RNA Viral/genética , RhizoctoniaRESUMO
The full-length nucleotide sequence and genome organization of a novel mycovirus designated as "Rhizoctonia fumigata partitivirus 1" (RfPV1) from Rhizoctonia fumigata AG-Ba strain C-314 Baishi was determined. The genome of RfPV1 consists of two double-stranded RNAs (dsRNAs): dsRNA1 (2003 bp) and dsRNA2 (1802 bp). Each of the two dsRNAs contains one open reading frame, coding for a putative RNA-dependent RNA polymerase and a coat protein, respectively. The 5' untranslated regions (UTRs) of both dsRNAs were conserved, and the 3'-UTRs of the two dsRNAs had interrupted poly(A) tails, similar to other partitiviruses. Phylogenetic analysis indicated that RfPV1 is a new species in the genus Alphapartitivirus, family Partitiviridae.
Assuntos
Micovírus , Vírus de RNA , Rhizoctonia/virologia , Micovírus/genética , Genoma Viral , Fases de Leitura Aberta , Filogenia , Vírus de RNA/genética , RNA de Cadeia Dupla/genética , RNA Viral/genéticaRESUMO
The full-length AU-rich (63.14%) 2,794-nucleotide sequence of Rhizoctonia mitovirus K1 (RMV-K1) isolated from the binucleate AG-K strain FAS2909W was determined. The positive strand of RMV-K1 contains a large open reading frame (ORF) when the fungal mitochondrial genetic code is used. This ORF was predicted to encode an RdRp protein exhibiting the highest sequence identity (41.77%) to Rhizoctonia solani mitovirus 30. Phylogenetic analysis showed that RMV-K1 is a novel member of the genus Mitovirus, family Mitoviridae.
Assuntos
Genoma Viral , Rhizoctonia , Filogenia , Doenças das Plantas , RNA Polimerase Dependente de RNA , Rhizoctonia/genéticaRESUMO
Accurate biomarkers to predict the genesis and progression of pancreatic adenocarcinoma (PAAD) are needed in the fight against this deadly disease. Here, we combined multiple datasets (GEO, TCGA and GTEx) to conduct a comprehensive analysis of pancreatic cancer. Through an in-depth analysis, we discovered that the expression of the gene encoding interferon alpha-inducible protein 27 (IFI27) was significantly higher in pancreatic cancer tissues than that in normal tissues, and that higher expression of IFI27 was negatively correlated with the overall survival rate of pancreatic cancer patients. The functional annotation of IFI27 demonstrated relationships to cellular immunity and metabolism, especially glycolysis. Analysis of infiltrating immune cells displayed that higher expression of IFI27 expression correlates with decreased CD8 + T cells and increased M2 macrophages in the tumor immune microenvironment (TIME), then biochemical analyses of a mouse model and immunohistochemical (IHC) staining verified that glycolytic enzymes and M2 macrophages increased significantly in pancreatic cancer tissues. We speculate that IFI27 may affect the tumor microenvironment (TME) of PAAD by regulating cellular immunity and metabolism, thereby promoting the progression of pancreatic carcinoma and worsening the prognosis. These findings of our present study are solid evidence that IFI27 is a potential prognostic biomarker of pancreatic cancer and that it affects the tumor immune microenvironment.
Assuntos
Biomarcadores Tumorais , Proteínas de Membrana , Neoplasias Pancreáticas , Transcriptoma/genética , Microambiente Tumoral , Animais , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Biologia Computacional , Feminino , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Pâncreas/metabolismo , Pâncreas/patologia , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Prognóstico , Microambiente Tumoral/genética , Microambiente Tumoral/imunologiaRESUMO
The complete genome sequence of a double-stranded RNA (dsRNA) virus, Rhizoctonia solani dsRNA virus 11 (RsRV11), isolated from Rhizoctonia solani AG-1 IA strain 9-11 was determined. The RsRV11 genome is 9,555 bp in length and contains three conserved domains: structural maintenance of chromosomes (SMC) superfamily, phosphoribulokinase (PRK), and RNA-dependent RNA polymerase (RdRp). The RsRV11 genome has two non-overlapping open reading frames (ORFs). ORF1 is predicted to encode a 204.12-kDa protein that shares low but significant amino acid sequence similarity with a putative protein encoded by Rhizoctonia solani RNA virus HN008 (RsRV-HN008). ORF2 potentially encodes a 132.41-kDa protein that contains the conserved domain of the RdRp. Phylogenetic analysis indicated that RsRV11 clustered with RsRV-HN008 in a separate clade from other virus families. This implies that RsRV11 and RsRV-HN008 should be included in a new mycovirus taxon close to the family Megabirnaviridae and that RsRV11 is a new mycovirus.
Assuntos
Micovírus/genética , Genoma Viral , Filogenia , Rhizoctonia/virologia , China , Micovírus/isolamento & purificação , Fases de Leitura Aberta , RNA de Cadeia Dupla , Rhizoctonia/isolamento & purificação , Proteínas Virais/genética , Zea mays/microbiologiaRESUMO
The Chinese white wax scale insect, Ericerus pela, is an important resource insect in China. The rapid response of E. pela to decreasing temperatures plays key roles in the population distribution. In this study, we analyzed the gene expression of E. pela treated with low temperature using transcriptome analyses and weighted gene coexpression network analysis (WGCNA). The results showed that the cold resistance of E. pela involved changes in the expression of many genes. The genes were mainly involved in alcohol formation activity, lipid metabolism, membrane and structure, and oxidoreductase activity. According to the WGCNA results, some pathways related to cold resistance were found in the genes in the modules, such as cytoskeleton proteins, cytoskeleton protein pathway, biosynthesis of unsaturated fatty acids, glycerophospholipid metabolism, ether lipid metabolism, and thermogenesis. Some of the hub genes were nonspecific lipid-transfer proteins, DnaJ homolog subfamily C member 13, paramyosin, tropomodulin, and tubulin beta chain. In particular, the hub genes of the tan module included the heat shock protein (hsp) 10, hsp 60, hsp 70, and hsp 90 genes. Thirty-five antifreeze protein (afp) genes were identified according to the annotation results. Three afp genes were further identified among the hub genes. Six of these genes were selected for heterogeneous protein expression. One of them was expressed successfully. The thermal hysteresis activity (THA) analyses showed that the THA was 1.73°C. These results showed that the cytoskeleton, lipid metabolism, thermogenesis, HSPs and AFPs may play important roles in the cold resistance of E. pela.
Assuntos
Proteínas Anticongelantes , Temperatura Baixa/efeitos adversos , Expressão Gênica , Hemípteros , Adaptação Biológica/genética , Animais , Proteínas Anticongelantes/genética , Proteínas Anticongelantes/metabolismo , Clonagem Molecular , Perfilação da Expressão Gênica , Genes de Insetos , Hemípteros/genética , Hemípteros/metabolismo , Proteínas de Insetos/metabolismoRESUMO
Nitrate-driven sulfide/ferrous oxidation has been proved a cost-effective approach for river sediments in-situ odor control. However, calcium nitrate addition would sharply increase ammonium concentration in interstitial water and the mechanism was not yet clear. In this work, though sulfide and ferrous iron were efficiently oxidized, about 102% of NH4+ concentration increased in interstitial water on the first day of calcium nitrate injection (30 mg kg dwt-1), and about 31% more NH4+ increase at the 21st days was observed. To discover the mechanism of ammonium sharp release, desorption kinetics experiment was conducted and the results suggested that the short-time sharp releases of ammonium when calcium nitrate was added could be attributed to the chemical extraction of exchangeable ammonium by calcium ion. Furthermore, at the end of treatment, many genus such as Thiobacillus, Sulfurimonas, Thermomonas, and Clostridium, which were closely related to sulfide and ferrous-driven denitrification and dissimilatory nitrate reduction to ammonium (DNRA), were identified by 16S rRNA Illumina sequencing method. These findings indicated the long-time increase of ammonium might be determined by the biochemical processes (e.g. DNRA) driven by nitrate reduction. Therefore, to avoid the impact of ammonium release, an alternative subsurface injection method was introduced in this work, and the results showed that ammonium releases could be well controlled when the injection position was beneath 10 cm of the sediment surface.