A glaucoma micro-stent with diverging channel and stepped shaft structure based on microfluidic template processing technology.

BACKGROUND: Minimally invasive glaucoma surgery (MIGS) has experienced a surge in popularity in recent years. Glaucoma micro-stents serve as the foundation for these minimally invasive procedures. Nevertheless, the utilization of these stents still presents certain short-term and long-term complications. This study aims to elucidate the creation of a novel drainage stent implant featuring a diverging channel, produced through microfluidic template processing technology. Additionally, an analysis of the mechanical properties, biocompatibility, and feasibility of implantation is conducted. RESULTS: The stress concentration value of the proposed stent is significantly lower, approximately two to three times smaller, compared to the currently available commercial XEN gel stent. This indicates a stronger resistance to bending in theory. Theoretical calculations further reveal that the initial drainage efficiency of the gradient diverging drainage stent is approximately 5.76 times higher than that of XEN stents. Notably, in vivo experiments conducted at the third month demonstrate a favorable biocompatibility profile without any observed cytotoxicity. Additionally, the drainage stent exhibits excellent material stability in an in vitro simulation environment. CONCLUSIONS: In summary, the diverging drainage stent presents a novel approach to the cost-effective and efficient preparation process of minimally invasive glaucoma surgery (MIGS) devices, offering additional filtering treatment options for glaucoma.

Maintaining Drosha expression with Cdk5 inhibitors as a potential therapeutic strategy for early intervention after TBI.

Traumatic brain injury (TBI) is a major cause of death and disability in adults. The pathological process of TBI involves a multifactorial cascade in which kinases have been proven contribute to interactions between relevant factors and amplification of signaling cascades. Cyclin-dependent kinase 5 (Cdk5) is a promising kinase that has been implicated in various brain disorders, including TBI. However, the mechanism by which Cdk5 induces neuronal damage remains unclear. Here, we show for the first time that Drosha, a key enzyme in microRNA biogenesis, is a pivotal substrate of abnormally activated Cdk5. Cdk5-mediated phosphorylation decreases Drosha expression and exacerbates nerve injury in TBI. We proved that maintaining Drosha expression via the administration of repurposed Cdk5 inhibitors that were previously studied in clinical trials is a promising approach for the early treatment of TBI. Together, our work identifies Drosha as a novel target for neuroprotective strategies after TBI and suggests Cdk5-mediated regulation of Drosha expression as a potential therapeutic strategy for early TBI intervention.

Direct regulation of FNIP1 and FNIP2 by MEF2 sustains MTORC1 activation and tumor progression in pancreatic cancer.

MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1) orchestrates diverse environmental signals to facilitate cell growth and is frequently activated in cancer. Translocation of MTORC1 from the cytosol to the lysosomal surface by the RRAG GTPases is the key step in MTORC1 activation. Here, we demonstrated that transcription factors MEF2A and MEF2D synergistically regulated MTORC1 activation via modulating its cyto-lysosome shutting. Mechanically, MEF2A and MEF2D controlled the transcription of FNIP1 and FNIP2, the components of the FLCN-FNIP1 or FNIP2 complex that acts as a RRAGC-RRAGD GTPase-activating element to promote the recruitment of MTORC1 to lysosome and its activation. Furthermore, we determined that the pro-oncogenic protein kinase SRC/c-Src directly phosphorylated MEF2D at three conserved tyrosine residues. The tyrosine phosphorylation enhanced MEF2D transcriptional activity and was indispensable for MTORC1 activation. Finally, both the protein and tyrosine phosphorylation levels of MEF2D are elevated in human pancreatic cancers, positively correlating with MTORC1 activity. Depletion of both MEF2A and MEF2D or expressing the unphosphorylatable MEF2D mutant suppressed tumor cell growth. Thus, our study revealed a transcriptional regulatory mechanism of MTORC1 that promoted cell anabolism and proliferation and uncovered its critical role in pancreatic cancer progression.Abbreviation: ACTB: actin beta; ChIP: chromatin immunoprecipitation; EGF: epidermal growth factor; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; FLCN: folliculin; FNIP1: folliculin interacting protein 1; FNIP2: folliculin interacting protein 2; GAP: GTPase activator protein; GEF: guanine nucleotide exchange factors; GTPase: guanosine triphosphatase; LAMP2: lysosomal associated membrane protein 2; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEF2: myocyte enhancer factor 2; MEF2A: myocyte enhancer factor 2A; MEF2D: myocyte enhancer factor 2D; MEF2D-3YF: Y131F, Y333F, Y337F mutant; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; NR4A1: nuclear receptor subfamily 4 group A member 1; RPTOR: regulatory associated protein of MTOR complex 1; RHEB: Ras homolog, mTORC1 binding; RPS6KB1: ribosomal protein S6 kinase B1; RRAG: Ras related GTP binding; RT-qPCR: real time-quantitative PCR; SRC: SRC proto-oncogene, non-receptor tyrosine kinase; TMEM192: transmembrane protein 192; WT: wild-type.

Chaperone-mediated autophagy degrades Keap1 and promotes Nrf2-mediated antioxidative response.

Accumulation of oxidative stress is highly intertwined with aging process and contributes to aging-related diseases, such as neurodegenerative diseases. Deciphering the molecular machinery that regulates oxidative stress is fundamental to further uncovering the pathogenesis of these diseases. Chaperone-mediated autophagy (CMA), a highly selective lysosome-dependent degradation process, has been proven to be an important maintainer of cellular homeostasis through multiple mechanisms, one of which is the attenuation of oxidative stress. However, the specific mechanisms underlying this antioxidative action of CMA are not fully understood. In this study, we found that CMA directly degrades Kelch-like ECH-associated protein 1 (Keap1), an adaptor of E3 ligase complex that promotes the degradation of nuclear factor erythroid 2-related factor 2 (Nrf2), which is a master transcriptional regulator in antioxidative response. Activated CMA induced by prolonged oxidative stress led to an increase in Nrf2 level by effectively degrading Keap1, contributing to Nrf2 nuclear translocation and the expression of multiple downstream antioxidative genes. Meanwhile, together with previous study showing that Nrf2 can also transcriptionally regulate LAMP2A, the rate-limiting factor of CMA process, we reveal a feed-forward loop between CMA and Nrf2. Our study identifies CMA as a previously unrecognized regulator of Keap1-Nrf2 pathway and reinforces the antioxidative role of CMA.

Hydroxyapatite-incorporation improves bone formation on endosseous PEEK implant in canine tibia.

BACKGROUND: Poly Ether Ether Ketone (PEEK) has been considered as a potential alternative material for endosseous dental implants, for its low elastic modulus, biocompatibility, and low cost in customized device manufacture. Hydroxyapatite-incorporation is supposed to improve the poor osseointegration of PEEK. METHODS: In the present study we analyzed the in vivo response of hydroxyapatite-incorporated PEEK (PEEK-HA) implants in canine tibia. PEEK-HA and PEEK implants were implanted and were examined 4 weeks and 12 weeks after implantation with radiology and histology. Commercial titanium dental implants served as controls. RESULTS: The ratio of bone volume to tissue volume of PEEK-HA implants was higher than that of PEEK implants 4 weeks after implantation in the µ-CT analysis. The bone implant contact of PEEK and PEEK-HA implants showed no statistical difference in the histological examination, but newly-formed bone around PEEK-HA implants showed more signs of mineralization than that around PEEK implants. CONCLUSION: The study suggested that bone formation was improved with hydroxyapatite-incorporation in PEEK. Hydroxyapatite-incorporated PEEK implants may represent a potential material for endosseous dental implant.

Transverse facial cleft (macrostomia) repair: Modification of a traditional technique.

OBJECTIVE: Outcomes from surgical repair of transverse facial cleft (macrostomia) may not be very satisfactory when conventional methods are used to position the oral commissure to be repaired. To improve patient outcomes, we developed a modified oral commissure positioning and reconstruction method for transverse facial cleft repair. METHOD: In the modified positioning method, the oral commissure at the abnormal side was positioned precisely and reconstructed by a combination of two conventional methods, namely, the distance measurement method and the anatomical charateristics method. The function of the orbicularis oris muscle was preserved. Postoperative surgical scar score and oral commissure symmetry score were determined and compared between patients and healthy controls. The scores ranged from one to five, with one representing the best and five indicating the worst results. RESULTS: Nine patients aged 4-31 months (7 girls) underwent the modified transverse facial cleft repair surgery. All the patients had unilateral transverse facial cleft with or without microsomia and/or complete cleft lip. The patients were followed up for one to five years. Although average surgical scar scores of patients (close-mouth: 1.8 ± 0.8, range: 1.0-2.8; open-mouth: 1.8 ± 0.9, range 1.0-3.6) remained significantly higher (P < 0.05) than those of the healthy controls (N = 8, close-mouth 1.1 ± 0.4, range: 1.0-1.4, open-mouth: 1.1 ± 0.3, range: 1.0-1.2) 6 months after the surgery, their average close-mouth oral commissure symmetry score (1.9 ± 0.7, range: 1.6-2.8) was similar (P = 0.381) to those of the healthy controls (1.8 ± 0.8, range: 1.0-2.6). CONCLUSIONS: The modified procedure appears to lead to promising long-term benefit on restoring oral commissure symmetry.

Multi-level customized 3D printing for autogenous implants in skull tissue engineering.

Three-dimensional (3D) printing of decellularized extracellular matrix (ECM) has been achieved to ensure real physiological environments for tissue engineering. However, the limited source, biocompatibility, and biosafety of decellularized ECM are deficiencies in its large clinical use. Autogenous ECM is biocompatible, bioactive, and biosafe, making it an optimal choice for future clinical applications of 3D printing. Here, we developed a multi-level customized 3D printing (MLC-3DP) strategy applying autogenous bone matrix (Auto-BM). This MLC-3DP includes shape specificity (shape), material specificity (Auto-BM), and cell specificity (autogenous cells) for true patient-specific repairs. Auto-BM (skull flaps) is readily accessible for specific patients after craniectomy, providing sufficient autogenous materials for MLC-3DP. Under mild conditions of this strategy, human-scale 3D printed samples can be fabricated using bioactive micron-sized Auto-BM particles. Multi-level customized autogenous bones (MLC-Auto-Bones) are finally obtained by combining autogenous bone marrow-derived mesenchymal stem cells (Auto-BMSCs). With autogenous materials and cells, MLC-Auto-Bones are inherently biocompatible and biosafe, providing good bioactivity for osteogenesis. In this implant, Auto-BMSCs can spontaneously differentiate into osteoblasts in vitro without additional osteogenic factors. In critical-sized skull defect models in vivo (3 months), implants integrate tightly to the defects' margin, facilitate mineralization, and generate vascularized mature bone. This work provides not only feasibility for patient-specific implants for skull defects, but also potential patient-specific solutions for other similar clinical requirements.

Integrated transcriptomic and proteomic analyses of a molecular mechanism of radular teeth biomineralization in Cryptochiton stelleri.

Many species of chiton are known to deposit magnetite (Fe3O4) within the cusps of their heavily mineralized and ultrahard radular teeth. Recently, much attention has been paid to the ultrastructural design and superior mechanical properties of these radular teeth, providing a promising model for the development of novel abrasion resistant materials. Here, we constructed de novo assembled transcripts from the radular tissue of C. stelleri that were used for transcriptome and proteome analysis. Transcriptomic analysis revealed that the top 20 most highly expressed transcripts in the non-mineralized teeth region include the transcripts encoding ferritin, while those in the mineralized teeth region contain a high proportion of mitochondrial respiratory chain proteins. Proteomic analysis identified 22 proteins that were specifically expressed in the mineralized cusp. These specific proteins include a novel protein that we term radular teeth matrix protein1 (RTMP1), globins, peroxidasins, antioxidant enzymes and a ferroxidase protein. This study reports the first de novo transcriptome assembly from C. stelleri, providing a broad overview of radular teeth mineralization. This new transcriptomic resource and the proteomic profiles of mineralized cusp are valuable for further investigation of the molecular mechanisms of radular teeth mineralization in chitons.

Gene expression profile analysis of U251 glioma cells with shRNA-mediated SOX9 knockdown.

PURPOSE: In glioma, the sex-determining region Y-box 9 gene (SOX9) is overexpressed and its downregulation leads to inhibition of cell proliferation, invasion and increased cell apoptosis. To further evaluate the molecular and signal pathways associated with the function of SOX9 and SOX9 target genes, a global gene expression profile of the established SOX9-knockdown U251 cells was investigated. METHODS: The molecular function and biological pathways of differentially expressed genes (DEGs) were identified by gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The interactome networks of DEGs were constructed using the STRING online tool. The genes were further validated by RT-qPCR. RESULTS: GO analysis revealed that a set of 194 DEGs was shared in both the SOX9 KD-1 and SOX9 KD-2 U251 cells. GO analysis and KEGG pathway analysis showed that the DEGs were associated with biological processes involving cellular responses to hypoxia, osteoblast differentiation and angiogenesis, and special biological pathways, such as a TGF-beta signaling pathway and a HIF-1 signaling pathway. In addition, computational network of novel identified potential target genes linked to SOX9, including TGFB2, VEGFA, EGLN3 (PHD3), CA9 and HIF-1a. All of these genes were downregulated in the SOX9 knockdown U251 cells. CONCLUSIONS: SOX9 may be a key regulator impacting the glioma cellular processes by influencing the cellular response to hypoxia and HIF-1 signaling pathway. TGFB2, VEGFA, EGLN3 (PHD3), CA9, and HIF-1a may be the target genes of SOX9.

Clinical application of a 3D-printed scaffold in chronic wound treatment: a case series.

OBJECTIVE: This case series evaluates the safety and effectiveness of 3D-printed scaffold in chronic wounds. The scaffold is a composite of natural and synthetic materials, and can be prepared in the form of powder or membrane. METHOD: We recruited patients with pressure ulcera (PU) and/or a diabetic foot ulcers (DFU). We used two methods: 3D-printed scaffolds alone, or 3D-printing powder mixed with platelet-rich fibrinogen (PRF). Clinicians and patients were asked to rate the scaffold's ease of application and comfort during use. RESULTS: A total of five patients were recruited; four with a PU and one with a DFU. For the patient treated with the 3D-printed scaffold membrane (n=1), their PU healed in 28 days, and for patients treated with the 3D-printed scaffold powder (n=2), their PUs healed in 54 days. For the patients treated with the 3D-printing powder mixed with PRF (n=2), the patient with a PU healed in 11 days, and the patient with the DFU healed in 14 days. All clinicians rated the 3D-printed scaffold as 'easy' or 'very easy' to use, and patients rated their comfort during wear and at dressing change as 'good' or 'very good'. CONCLUSION: This study demonstrated that 3D-printed scaffold was convenient to use, have the potential to improve wound healing rates, and provided a safe and effective way for treating chronic wounds.

Genetic variants of SOX9 contribute to susceptibility of gliomas among Chinese population.

Gliomas make up about 80% of all malignant brain tumors, and cause serious public health problem. Genetic factors and environmental factors jointly caused the development of gliomas, and understanding of the genetic basis is a key component of preventive oncology. However, most genetic factors underlying carcinogenesis of gliomas remain largely unclear. In current study, we systematically evaluated whether genetic variants of SOX9 gene, a transcription factor that plays a central role in the development and differentiation of tumors, contribute to susceptibility of gliomas among Chinese population using a two-stage, case-control study. Results showed that SOX9 rs1042667 was significant associated with increased gliomas risk after adjusted by age, gender, family history of cancer, smoking status and alcohol status (Allele C vs A: OR=1.25; 95% CI=1.11-1.40; P=1.2×10-4). Compared with the carriers of genotype AA, both those of genotype AC (OR=1.37; 95% CI=1.13-1.66) and CC (OR=1.53; 95% CI=1.22-1.91) had significantly increased gliomas risk. This should be the first genetic association study which aims to evaluated the association between genetic variants of SOX9 and susceptibility of gliomas. Additional functional and association studies with different ethnic groups included are needed to further confirm our results.

ClC-3 Expression and Its Association with Hyperglycemia Induced HT22 Hippocampal Neuronal Cell Apoptosis.

Although apoptosis plays an important role in the development of Diabetic Encephalopathy (DE), the underlying molecular mechanisms remain unclear. With respect to this, the present work aims to study the variation in chloride/proton exchanger ClC-3 expression and its association with HT22 hippocampal neuronal apoptosis under hyperglycemic condition in vitro. The cells were stimulated with added 0, 5, or 25 mM glucose or mannitol for up to 72 hours before assessing the rate of ClC-3 expression, cell viability, and apoptosis. In a consecutive experiment, cells received chloride channel blocker in addition to glucose. The rate of cellular death/apoptosis and viability was measured using Flow Cytometry and MTT assay, respectively. Changes in ClC-3 expression were assessed using immunofluorescence staining and western blot analysis. The results revealed a significant increase in cellular apoptosis and reduction in viability, associated with increased ClC-3 expression in high glucose group. Osmolarity had no role to play. Addition of chloride channel blocker completely abolished this effect. Thus we conclude that, with its increased expression, ClC-3 plays a major role in hyperglycemia induced hippocampal neuronal apoptosis. To strengthen our understanding of this aforesaid association, we conducted an extensive literature search which is presented in this paper.

Assembly of Layered Monetite-Chitosan Nanocomposite and Its Transition to Organized Hydroxyapatite.

Bioinspired synthesis of hierarchically structured calcium phosphate (CaP) material is a highly promising strategy for developing improved bone substitute materials. However, synthesis of CaP materials with outstanding mechanical properties still remains an ongoing challenge. Inspired by the formation of lamellar structure in nacre, we designed an organic matrix composed of chitosan and cis-butenediolic acid (maleic acid, MAc) that could assemble into a layered complex and further guide the mineralization of monetite crystals, resulting in the formation of organized and parallel arrays of monetite platelets with a brick-and-mortar structure. Using the layered monetite-chitosan composite as a precursor, we were able to synthesize hydroxyapatite (HAp) with multiscale hierarchically ordered structure via a topotactic phase transformation process. On the nanoscale, needlelike HAp crystallites assembled into organized bundles that aligned to form highly oriented plates on the microscale. On the large-scale level, these plates with different crystal orientations were stacked together to form a layered structure. The organized structures and composite feature yielded CaP materials with improved mechanical properties close to those of bone. Our study introduces a biomimetic approach that may be practical for the design of advanced, mechanically robust materials for biomedical applications.

Amelogenin Affects Brushite Crystal Morphology and Promotes Its Phase Transformation to Monetite.

Amelogenin protein is involved in organized apatite crystallization during enamel formation. Brushite (CaHPO4·2H2O), one of the precursors of hydroxyapatite mineralization in vitro, has been used for fabrication of biomaterials for hard tissue repair. In order to explore its potential application in biomimetic material synthesis, we studied the influence of the enamel protein amelogenin on brushite morphology and phase transformation to monetite. Our results show that amelogenin can adsorb onto the surface of brushite, leading to the formation of layered morphology on the (010) face. Amelogenin promoted the phase transformation of brushite into monetite (CaHPO4) in the dry state, presumably by interacting with crystalline water layers in brushite unit cells. Changes to the crystal morphology mediated by amelogenin continued even after the phase transformation from brushite to monetite, leading to the formation of organized platelets with an interlocked structure. This effect of amelogenin on brushite morphology and the phase transformation to monetite could provide a new approach to developing biomimetic materials.

[Preparation and characterization of monoclonal antibodies against F domain of human progranulin].

OBJECTIVE: To prepare and characterize the monoclonal antibody (mAb) against F domain of human progranulin (GrnF). METHODS: Yeast expression vector containing GrnF gene was constructed using molecular biological technology. Then eukaryotic fusion protein human serum albumin (HSA)-GrnF from yeast vector was expressed and purified. BALB/c mice were immunized by the purified HSA-GrnF fusion protein. The splenocytes of the BALB/c mice were isolated from spleen and fused with Sp2/0 myeloma cells. Indirect ELISA and limiting dilution assay were used for screening hybridoma cell lines. The specificity of monoclonal antibodies against GrnF was evaluated with indirect ELISA, Western blotting and immunohistochemistry. The immunoglobulin subclass was identified with mouse monoclonal antibody isotyping reagents. RESULTS: Two hybridoma cell lines, 1G6 and 4E8, were obtained and heavy chain subclasses of the two hybridoma cell lines were IgG1. CONCLUSION: The mAbs that can specifically recognize GrnF have been successfully prepared.

The co-effect of organic matrix from carp otolith and microenvironment on calcium carbonate mineralization.

In vitro mineralization experiment is an effective way to study the effect of organic matrix on calcium carbonate crystallization, and to reveal the relationship between organic matrix and inorganic crystal in natural biominerals. In natural biominerals, organic matrix plays an important role in crystal formation and stability, together with microenvironment changes, they can affect crystal polymorph, morphology, density, size, orientation etc. In this work, we systematically studied the effects of different organic matrices in fish otoliths, the organic matrix concentration changes, as well as the co-effect of organic matrices with temperature, pH value and Mg ion changes in the in vitro CaCO3 mineralization experiments. The organic matrix and concentration change experiments prove that water soluble matrix (WSM) plays an important role in crystal form transition. It can induce CaCO3 crystals with same crystal polymorph as the otolith from which organic matrix was extracted. The temperature change experiment proves that CaCO3 has a tendency to form calcite, vaterite, and then aragonite in priority as temperature goes up. Under different temperature, WSM from lapillus/asteriscus still has the effect to mediate different CaCO3 crystals. The pH change experiment shows that, near the neutral environment, as pH value goes up, calcites have a tendency to form crystal aggregates with more faces exposed, the organic matrix still keeps crystal mediation effect. The Mg(2+) experiment shows that, Mg ion can promote aragonite formation, together with lapillus organic matrix, aragonites with different shapes are formed.

Comparative study of carp otolith hardness: lapillus and asteriscus.

Otoliths are calcium carbonate biominerals in the inner ear of vertebrates; they play a role in balance, movement, and sound perception. Two types of otoliths in freshwater carp are investigated using nano- and micro-indentation: asteriscus and lapillus. The hardness, modulus, and creep of asteriscus (vaterite crystals) and lapillus (aragonite crystals) are compared. The hardness and modulus of lapillus are higher than those of asteriscus both in nano- and micro-testing, which is attributed to the different crystal polymorphs. Both materials exhibit a certain degree of creep, which indicates some time dependence of the mechanical behavior and is attributed to the organic components. The nano-indentation hardnesses are higher than micro-hardnesses for both otoliths, a direct result of the scale dependence of strength; fewer flaws are encountered by the nano than by the microindenter.

Effects of additives and templates on calcium carbonate mineralization in vitro.

The review focuses on the effects of several important additives and templates controlling the calcium carbonate crystals formation and the complexity of the crystal morphologies in vitro. Additives include soluble matrices extracted from shells and pearls, amino-acids, magnesium ions and collagen among others. Templates include modified single crystal silicon, natural biominerals among others. Mechanisms proposed to explain the phenomena are not systematic, further studies are necessary to explain how organic matrices mediate calcium carbonate mineralization.

Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization.

Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH2 and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH2 and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different.

The relationship between trace elements in fish otoliths of wild carp and hydrochemical conditions.

The trace element composition of the fish otolith is an indicator of biomineralization. In contrast to other skeletal tissue, the otolith retains its entire original structure and does not absorb any elements after the fish dies. Because otoliths in carp degrade very slowly in the dead body, the information it provides on the environment is retained, even in fossil form. Here, we report our analysis of the trace elements in otoliths of carp and of the water in Donghu Lake and Longhupao Lake, Heilongjiang province, China, where the fish lived. The results revealed that the trace elements found in the carp otoliths were clearly correlated with those found in these water bodies. There were high concentrations of Au, Ba, K, Sr and Zn in both the water and otoliths; in contrast there were high levels of As, Na and Se in water, but low concentrations in otoliths. These results indicate that an analysis of the otoliths of carps provides an accurate procedure for studying the surrounding hydrochemistry conditions. The interaction of the elements during deposition was also studied. The correlation coefficients of 13 trace elements identified in the otoliths in both lakes were calculated.