Tailings Samples Research Articles

Evaluation of Silver Recovery from High-Sulphur Mining Waste Using Thiourea–Oxalate System

Mine tailings are a byproduct of mineral extraction and often pose an environmental challenge due to the contamination of soil and water bodies with dissolved metals. However, this type of waste offers the opportunity for the recovery of valuable metals such as silver (Ag). In the present investigation, an integral analysis of a sample of tailings was carried out, addressing granulometry, elemental composition, neutralization potential (NP), and acid potential (AP), as well as mineralogy, for the dissolution of silver from this type of waste. For this purpose, thiourea (CH4N2S) was used as a leaching agent due to its low toxicity, and potassium oxalate (K2C2O4) was used as an organic additive to improve the leaching of the silver phases (argentite and polybasite) present in the tailings. The effects of CH4N2S and K2C2O4 concentrations, temperature, and pH on the leaching efficiency of silver (Ag), copper (Cu), iron (Fe), and arsenic (As) were systematically studied. The results revealed that the maximum silver dissolution rate reached 90.75% under optimal conditions: 0.2 M L−1 of thiourea and 0.2 M L−1 of potassium oxalate, at 35 °C and a pH of 2.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ВЫДЕЛЕНИЯ ДНК ИЗ УШНЫХ ТКАНЕЙ И ХВОСТОВ СВИНЕЙ (SUS SCROFA DOMESTICUS)

Extraction of DNA from tissue samples is the initial stage in molecular genetic studies of farm animals. Cur- rently, in the Russian Federation, the creation of extensive DNA biobanks for deep retrospective analysis for the purposes of genomic selection is relevant. In the livestock industry, studies of the genome and transcriptome of pigs (Sus scrofa domesticus) are especially important for identifying new genetic markers of economically valua- ble animal traits and developing effective postgenomic approaches to targeted selection, genetic certification and obtaining lines with new characteristics. The purpose of this study was to determine and compare the quality and quantity of DNA obtained from tissue samples of ear notches and tails of pigs using a commercially available kit by the method of sorption on magnetic particles «Tissue M», Raissol Bio (Russia). As a result, both types of bio- logical samples showed a high yield of DNA, however, the maximum DNA concentrations were observed when using tail samples (725.1 ng/μl) and, in general, the average result was higher (337.2 ng/μl) than when using ear notches (146 ng/μl). The spectral characteristics of the obtained DNA also showed a good result within the per- missible values. Quality control of the isolated DNA using PCR with a «random» primer showed its high quality and suitability of the obtained DNA for subsequent molecular genetic studies. Thus, based on the data obtained, it was concluded that piglet tails are suitable as biological material for isolating high-quality genomic DNA for fur- ther molecular genetic studies.

An improved method for whole-mount in situ hybridization in regenerating tails of Xenopus laevis tadpoles

Whole-mount in situ hybridization (WISH) is a widely used method that supports the concept of “seeing is believing” by enabling the visualization of gene expression patterns in whole-mount multicellular samples or sections. This technique is essential in the study of epimorphic regeneration in cold-blooded vertebrates, where complex three-dimensional organs such as tails, limbs, and eyes are completely restored after loss. The tadpoles of the frog X. laevis serve as a convenient model for studying regeneration, as they can regenerate their tails within a week after amputation. Modern high-throughput sequencing methods have identified various cell populations involved in the regeneration process and determined the repertoire of genes activated during this time. Specifically, a population of reparative myeloid cells expressing mmp9 as a marker gene has been shown to be crucial for the initial stages of tail regeneration in X. laevis tadpoles. The validation of these data and further examination using WISH offers the advantage of providing detailed information on the spatial and temporal dynamics of target gene expression levels. However, detecting mRNA by WISH can be challenging when mRNA levels are very low, transcripts are localized in hard-to-access areas, or tissue samples are prone to background staining, as is the case with X. laevis regenerating tail samples. Here, we describe additional treatments for regenerating tail samples that minimize background staining and enhance the visualization of cells containing target RNA through in situ hybridization. Using an optimized WISH protocol on X. laevis tadpole tail regenerates, we obtained novel data on the mmp9 expression pattern during the first day post-amputation at the regeneration-competent stage 40 and the regeneration-incompetent stage 47 (refractory period). The significant differences in the expression patterns indicate that mmp9 activity is positively correlated with regeneration competence.

Hazard Study of Sludge from Mining Wastewater Treatment Systems (Tailings), Accumulation of Contaminants and Potential Utilization Proposals

The increase in gold mining activities has led to a substantial rise in tailings generation, which carry distinct physicochemical and microbiological properties. This study aimed to evaluate the hazardous characteristics of mining tailings using the CRETIB (corrosivity, reactivity, explosiveness, toxicity, ignitability, biological-infectious) methodology. The research analyzed concentrations of heavy metals including arsenic, cadmium, copper, chromium, lead, mercury, nickel, and zinc, alongside parameters such as pH, cyanide, hydrogen sulfide, and coliform bacteria. Tailings samples were collected from a mine in Ponce Enriquez, Ecuador, at the surface and at a depth of 2 m across three monitoring campaigns. The results indicate that the tailings do not exhibit hazardous characteristics according to CRETIB criteria. While arsenic, chromium, copper, nickel, zinc, and mercury concentrations showed significant differences between the surface and 2 m depth, accumulating at the bottom of the tailings dam by 30–72%, parameters such as pH, cyanide, and hydrogen sulfide were higher at the surface, likely due to volatilization and precipitation effects. Lead did not show significant differences, but also tended to accumulate at depth. These findings suggest that the tailings could be safely utilized in the production of construction materials such as bricks, geopolymer concrete, and fiber cement, promoting circular economy practices and sustainable development in mining.

Assessment of Metal Enrichment in the Koma Bangou (Niger) Gold Panning Area Soils and Tailings

Artisanal and small-scale gold mining at Koma Bangou (Niger) has been going on since the Sahelian 1984’s drought, with introduction of ore leaching in the year 2009. The use of chemicals in the ore processing results in metal enrichment and pollution at the cyanidation sites. The aim of this work is to assess the metal enrichment of soils and tailings at Koma Bangou. Geochemical data acquired with portable XRF analyzer corrected with ICP-MS data, were used to assess the enrichment level of As, Cr, Cu, Mn, Pb and Zn in the soils and tailings samples using the enrichment factor and soil-geochemical baseline data for the Koma Bangou soils. The metallic enrichment generated by the ore processing was identified in the tailings (cyanidation and acidification waste) and the soils from the cyanidation areas. The perimeter soils (soils outside cyanidation sites) show no metal enrichment. Pb and As are extremely high to very high enriched in the cyanidation waste, with an average enrichment factor value of 44.96 and 34.96 respectively. Zn, Cu, Cr are extremely high to significant enriched in the acidification waste, with an average enrichment factor value of 793.35, 29.46 and 5.22 respectively. Mn enrichment is insignificant in all of the samples with an average enrichment factor value of 1.00 in the perimeter soils. The gold ore leaching activities generate metallic pollution of the soil, water and vegetation around the cyanidation sites.

Mixed Mutual Transfer for Long-Tailed Image Classification.

Real-world datasets often follow a long-tailed distribution, where a few majority (head) classes contain a large number of samples, while many minority (tail) classes contain significantly fewer samples. This imbalance creates an information disparity between head and tail classes, which can negatively impact the performance of deep networks. Some transfer knowledge techniques attempt to mitigate this gap by generating additional minority samples, either through oversampling the tail classes or transferring knowledge from the head classes to the tail classes. However, these methods often restrict the diversity of the generated minority samples, primarily focusing on transferring information only to the tail classes. This paper introduces a simple yet effective method for long-tailed classification, called mixed mutual transfer (MMT), which facilitates the mutual transfer of knowledge between head and tail classes by blending samples. The core idea of our method is to create new samples by blending head and tail samples. Head samples are selected using a uniform sampler that retains the long-tailed distribution, while tail samples are selected using a differential sampler that reverses the long-tailed distribution to alleviate imbalance. Our approach aims to diversify both tail and head classes. During the training phase, we utilize the generated samples to update the original dataset for training deep networks. Mixed mutual transfer simultaneously enhances the performance of both head and tail classes. Experimental results on various class-imbalanced datasets show that the proposed method significantly outperforms existing methods, demonstrating its effectiveness in improving the performance of long-tailed deep networks.

Unbiased scene graph generation via head-tail cooperative network with self-supervised learning

Scene Graph Generation (SGG) as a critical task in image understanding, facing the challenge of head-biased prediction caused by the long-tail distribution of predicates. However, current debiased SGG methods can easily prioritize improving the prediction of tail predicates while ignoring the substantial sacrifice of head predicates, leading to a shift from head bias to tail bias. To address this issue, we propose a Head-Tail Cooperative network with self-supervised Learning (HTCL), which achieves unbiased SGG by cooperating head-prefer and tail-prefer predictions through learnable weight parameters. HTCL employs a tail-prefer feature encoder to re-represent predicate features by injecting self-supervised learning, which focuses on the intrinsic structure of features, into the supervised learning of SGG, constraining the representation of predicate features to enhance the distinguishability of tail samples. We demonstrate the effectiveness of our HTCL by applying it to VG150, Open Images V6 and GQA200 datasets. The results show that HTCL achieves higher mean Recall with a minimal sacrifice in Recall and achieves a new state-of-the-art overall performance. Our code is available at https://github.com/wanglei0618/HTCL.

Environmental risk and source analysis of heavy metals in tailings sand and surrounding soils in Huangshaping mining area

ABSTRACT To investigate the ecological risk, the modes of occurrence, and pollution sources of heavy metals in the tailings sand and surrounding soils of Huangshaping mining area, a total of six tailings samples and ten soil samples from surrounding agricultural and forestry lands were collected. The current status and sources of soil heavy metal pollution in the study area are analyzed using a series of ecological risk assessment methods. The ecological risk assessment results show that most of the soils in the study area have reached a moderate or higher level of pollution.. The analysis of the modes of occurrence of heavy metals shows that the content of Cd and Zn in their effective forms is relatively high, accounting for 81% and 69% respectively. Source apportionment results indicate that the main sources of heavy metal pollution in the study area are the combined sources of industry, transportation, and agriculture.

Methylmercury Concentrations More Strongly Associated With Trait Variation Than Food Web Position in Plethodontid Salamanders.

Salamanders serve as bioindicators of mercury (Hg) in both terrestrial and aquatic habitats and are an important link in the food web between low-trophic prey and higher-trophic predators. We investigated the drivers of methylmercury (MeHg) exposure in three common plethodontid salamander species in New York State, USA, including comparisons among regions, habitat types (terrestrial and semiaquatic), and color morphs of Plethodon cinereus (striped and unstriped). Nonlethal tail samples were collected from one terrestrial species (P. cinereus) and two semiaquatic species (Eurycea bislineata and Desmognathus spp.) in the Adirondack Mountains (ADK) and the Finger Lakes National Forest (FLNF) regions. Samples were analyzed for MeHg and stable isotopes, including δ15N and δ13C which are proxies of trophic position and diet, respectively. Despite elevated biota Hg concentrations typically found in the ADK, salamander MeHg concentrations did not differ by region in the terrestrial species and one of the semiaquatic species. In addition, diet and trophic level did not explain MeHg exposure in salamanders. Semiaquatic salamanders exhibited higher MeHg concentrations than terrestrial salamanders in the FLNF only. Within species, only snout-vent length predicted MeHg concentrations in E. bislineata with few other variables significant as predictors of MeHg concentrations in path models. Among P. cinereus individuals in the FLNF, the striped morph had greater MeHg concentrations than the unstriped morph, and food web tracers were not different between morphs. Overall, New York State salamander Hg concentrations were elevated compared to other locations where these species are present. The present study establishes baseline Hg data in salamanders for future assessments of changes in Hg bioavailability to forests of New York State. Environ Toxicol Chem 2024;43:2045-2057. © 2024 SETAC.

On the Behavior of Bauxite Tailings under a Wide Range of Stresses

Despite its vital importance to the contemporary economy, some drawbacks are mainly associated with waste derived from mining activity. This waste consists of tailings that are hydraulically disposed of in large impoundments, the tailings dams. As the dams are enlarged to accommodate higher amounts of materials, the stress states at which the deposited tailings are submitted change. This may be a concern for the stability of such structures once the geotechnical behavior of this material may be complex and challenging to predict, considering the existing approaches. Thus, the present study concerns the mechanical response of bauxite tailings under a wide span of stresses, ranging from 25 kPa to 4000 kPa. One-dimensional compression tests and isotropically drained and undrained triaxial tests were carried out on intact and remolded samples of the bauxite tailings. The after-shearing grain size distribution was characterized via sedimentation analysis. The results have shown a stress-dependency of the critical state friction angle for the intact material, which may be related to fabric alterations derived from structure deterioration and particle breakage. Overall, this research provides valuable insights into the response of structured and de-structured bauxite tailings, which are helpful for future constitutive modeling of such material.

Comprehensive evaluation of leaching toxicity of tailings in non-resource-based cities in Anhui Province based on entropy weight-clustering method

<p>Toxic components in tailings pose a severe threat to the ecosystem and human health and negatively affect tailings’ resource utilization. Therefore, using the entropy weight-clustering method, we evaluated the leaching toxicity based on tailings samples from non-resource cities in Anhui Province. The results show that, all the extracted tailings samples first passed the leaching toxicity test, but there is still a large room for improvement. Secondly, there are complex interrelationships among the 15 indicators measuring leaching toxicity. Thirdly, in the process of entropy weight method calculation, the top three indicators in terms of weight are Cu (17.65%), Ag (16.52%), and Be (8.66%). Finally, the Ward clustering results show that the toxicity scores of tailings in each mining area exhibit distinct hierarchical characteristics, and they can be divided into two major categories and three subcategories (Ⅰ-1, Ⅰ-2, Ⅱ), with the toxicity scores of category Ⅰ-1 significantly higher than the rest of the mining areas. These findings provide empirical evidence for targeted treatment of tailings resources.</p>

Tellurium Enrichment in Copper Tailings: A Mineralogical and Processing Study

As the global demand for tellurium (Te) increases, it is crucial to develop efficient recovery methods that consider existing supply streams. This research combines gravity separation and froth flotation processes to enhance the recovery of Te minerals from tailings produced during the beneficiation of copper porphyry ores. Prior to processing, a systematic and comprehensive characterization study of copper tailing (CT) samples was conducted to examine the deportment of Te minerals in different mineral phases and to understand their locking and liberation behavior. Characterization techniques included inductively coupled plasma mass spectrometry (ICP-MS) and TESCAN’s integrated mineral analysis (TIMA). Copper tailing characterization showed that minerals with gold (Au), silver (Ag), bismuth (Bi), and Te were present in various forms, including native Au, electrum, tellurides, and sulfosalts. TIMA revealed that >90% of these minerals were primarily hosted in pyrite as less than 10 µm inclusions in the CT. TIMA also revealed that Te minerals exhibited fine-grained liberation of less than 20 μm. Moreover, TIMA results showed that >80% of mica and other silicate minerals were concentrated in size fractions < 38 μm, suggesting that desliming processes would positively impact Te enrichment. The results from the processing tests showed a Te recovery rate of ~77% and a Te enrichment ratio of 13 when using the combination of gravity separation and froth flotation at 90 g/t xanthate collector and 50 g/t glycol frother. The findings from this study show a significant potential for Te recovery from unconventional sources if appropriate physical beneficiation approaches are adopted.

Exploring the Coagulant Capability of Moringa oleifera seed powder at reducing Turbidity in Gold Mine Tailings Slurry

Moringa oleifera is characterised as an effective alternative to traditional approaches for the treatment of gold mine tailings spoils, particularly for its low cost, non-toxic nature, and simple application. This study investigated the use of M. oleifera seed powder as a primary coagulant for the treatment of gold mine tailings with respect to turbidity reduction, and the effect of varying pH on the coagulation process. The tailings sample used in the study was collected from an active mining operation in the Waiamu area, Cuyuni Mining District 4, Guyana; with the average turbidity ranging between 216.33 ± 4.62 and 275.33 ± 8.33 NTU. The standard jar test procedure was used to assess the efficiency of the M. oleifera coagulant based on measurements of turbidity reduction. M. oleifera was found to be an effective coagulant for reducing turbidity in the selected gold mine tailing pond, with the best turbidity reduction being 91.31 ± 0.53%. Further evidence from the study suggested that at the optimum coagulant concentration of 250mg/L, turbidity reduction changed as pH levels (5, 6, 7, 8, 9) were altered, whereby reduction at the natural pH level of 7 (control) was 91.31 ± 0.53%; and following adjustments of pH levels to 5, 6, 8 and 9, turbidity was reduced by 85.00 ± 0.58%, 84.88 ± 0.94%, 77.81 ± 5.21% and 74.16 ± 5.28% respectively. Therefore, strong knowledge of biological approaches for the treatment of gold mine tailings spoils would be pivotal to support long-term decisions on wastes management and disposal.

Characterization and utilization potential of typical molybdenum tailings in Shaanxi Province, China.

Shaanxi Province is located in the most important molybdenum ore district in the world, but a lot of molybdenum tailings have been released, polluting the environment and wasting resources seriously. Taking eleven tailing samples collected at the main molybdenum tailings ponds in Shaanxi Province as the research object, the physical, chemical, and mineralogical characteristics were studied through scanning electron microscope, X-ray fluorescence, X-ray diffraction, inductively coupled plasma mass spectrometer, and others. The ecological risk and utilization potential of molybdenum tailings were investigated through leaching test, geo-accumulation index, potential ecological risk assessment, and other methods. The results demonstrated that the main chemical and mineralogical composition of various molybdenum tailings in Shaanxi Province is similar, and the predominant mineral composition is muscovite, quartz, microcline, and calcite. The potential ecological risk of heavy metals in six molybdenum tailings is high, while Pb and Cd are the main pollution risk elements. Molybdenum tailings contain considerable amounts of critical minerals with huge potential economic value, and molybdenum tailings with high environmental hazards could be converted into a possible source for critical minerals by recovering the critical minerals and repurposing the secondary tailings as an additive or cement substitute. This study provides an innovative idea for the pollution treatment of molybdenum tailings and indicates the prospect of molybdenum tailings as a secondary source for critical minerals.

Characterization of medium and small-scale gold processing operations, wastewaters, and tailings in the Arequipa region of Peru

Gold cyanidation facilities in the Arequipa Region of Peru are challenged by the availability and quality of water for processing in an arid environment. The facilities reuse decant water which recycles residual cyanide but also undesirable constituents. To understand the impact of intensive water recycling on cyanide and metals concentrations, we collected barren water, decant water, and tailings samples from six gold cyanidation facilities with ore capacities of 10–430 tons per day. Processing facilities in Arequipa recycle all effluents, with decant waters making up 58 ± 11 % of process waters. Decant water contained non-target metals: copper (394 ± 161 mg/L), iron (59 ± 34 mg/L), and zinc (74 ± 42 mg/L). In addition, decant water mean free and complexed cyanide concentrations were 534 ± 129 mg/L and 805 ± 297 mg/L, respectively. Complexed cyanide concentrations remained more constant than free cyanide concentrations with 786 ± 299 mg/L for barren water and 805 ± 297 mg/L for decant water. Cyanide mass balances showed between 21 % and 42 % of unaccounted free cyanide from the start of gold cyanidation and discharge to the tailings storage facility (TSF). Free cyanide estimated losses due to volatilization were 0.8 kg and 2.5 kg of hydrogen cyanide per ton of ore processed at barren water pH of 10.1 and 9.7. Together these results indicate two acute hazards: 1) volatilization of free cyanide during processing and 2) loading and retention of cyanides and metals into TSFs. This study elucidates the extent of uncontrolled vapor phase cyanide release during gold processing operation and contaminant concentrations in the tailings storage facilities. The data highlights the need for improvement oversight, accountability, and regulation of gold processing facilities practicing intensive recycling and zero discharge.

Geochemical and mineralogical heterogeneity of the Cantung mine tailings: implications for remediation and reprocessing

Reprocessing tailings to recover minerals of economic interest and environmental concern can add value to a project and decrease environmental risk, but dealing with heterogeneity within tailings facilities is a challenge. This study investigates the heterogeneity of the Cantung Mine tailings to assess the potential for reprocessing for both value recovery and remediation purposes. The Cantung Mine, Northwest Territories, was a world-class tungsten (W) deposit that was mined periodically from 1962 to 2015. Geochemical analysis of 196 tailings samples shows substantial heterogeneity in the elements of value (tungsten and copper (Cu)) and elements of environmental concern for acid rock drainage (iron (Fe) and sulfur (S)). Tungsten and copper concentrations range from 0.06 to 1.06 wt% W (average 0.32 wt% W) and 0.05 to 0.48 wt% Cu (average 0.23 wt% Cu). Iron and sulfur concentrations range from 8.25 to 34.08 wt% Fe (average 17.14 wt% Fe) and 2.20 to 19.70 wt% S (average 6.7 wt% S). Characterization of 29 samples by scanning electron microscope with automated mineralogy software shows that geochemical heterogeneity corresponds to mineralogical heterogeneity with variability in the concentrations of scheelite (CaWO4), chalcopyrite (CuFeS2) and pyrrhotite (Fe(1-x)S). Liberation analyses indicate that additional grinding would be necessary to recover scheelite, chalcopyrite or pyrrhotite. Pyrrhotite with monoclinic and hexagonal-orthorhombic forms were identified. Overall, the Cantung tailings display considerable heterogeneity, which could lead to difficulties in reprocessing for economic or environmental benefit, but characterizing the heterogeneity allows for systems to be optimized.

Evaluation of the Efficiency of Using an Oxidizer in the Leaching Process of Gold-Containing Concentrate

This article presents the results of cyanide leaching of gold-containing concentrate using the trichlorocyanuric acid (TCCA) oxidizer. Gold-containing concentrate was obtained from a gold tailings sample from a gold recovery factory (GRF) in one of the deposits of Kazakhstan that have not previously been studied for concentrability. According to X-ray phase analysis and energy dispersive spectrometry (DSM) data, the main compounds in the tailings sample under study are pyrite FeS2, quartz SiO2, calcite CaCO3, albite NaAlSi3O8, muscovite KAl2Si3AlO10(OH)8, dolomite CaMg(CO3)2, and oxidized iron compounds. Microscopic studies of the concentrate have established the presence of ultrafine gold with sizes from Au 0.9 to 10.2 μm in pyrite. Obtaining the gold-containing concentrate with a gold content of 15.95 g/t is possible according to the enrichment scheme, which includes centrifugal separation, classification according to the fineness class −0.05 mm, additional grinding of hydrocyclone sands to a fineness of 90.0–95.0% of the class finer than 0.050 mm, and control centrifugal separation. Since pyrite in technogenic raw materials is the main gold-containing mineral, this paper presents studies on the oxidizability of pyrite with the TCCA oxidizer. The results of studies on the oxidation of pyrite using the TCCA oxidizer show the products of its hydrolysis oxidize pyrite with the formation of various iron compounds on its surface. Pretreatment of gold-containing concentrate with oxidizer TCCA for 3 h before the cyanidation process (20 h) allows for an increase in the recovery of gold in the solution by 5.8%.

Assessment of Mercury Contamination in Water and Soil from Informal Artisanal Gold Mining: Implications for Environmental and Human Health in Darmali Area, Sudan

Mercury contamination stemming from artisanal and small-scale gold mining (ASGM) operations poses significant environmental and health concerns. This study focuses on the Darmali area in River Nile State, Sudan, where the reprocessing of amalgamation tailings has led to mercury contamination. This study assessed the mercury content in soil and tailings samples, as well as in tap and groundwater, to evaluate the human health risks from ASGM activities and assess contamination levels within the study area. Soil and water samples were collected from various locations, including agricultural, residential, and tailings sites, as well as groundwater and tap water from the Nile. Mercury analysis was conducted using MA-3000 (NIC), and geo-accumulation index analysis revealed extreme pollution levels in areas with tailings and moderate pollution levels in agricultural and residential areas. Hazard quotients were applied to assess health risks, with inhalation of mercury vapor identified as the primary exposure route. The results indicated that tailings pose significant health risks, particularly for children, while water samples and soil from agricultural and residential areas did not pose significant risks. These findings underscore the urgent need for authorities and local communities to address mercury contamination by removing and treating tailings from affected areas to mitigate health risks.

Feeding Status Transiently Alters the Phosphorylation of Enzymes in the PI3K/Akt/GSK3β Pathway but not Phosphorylated Tau in the Cortex of Male Obese Zucker Rats

Metabolic syndrome (MetS) fosters pathological brain markers such as excess phosphorylated tau (ptau) to produce neuronal dysfunction. Activation of the PI3K/Akt/GSK3β pathway by increasing pAkt-Ser473 and pGSK3β-Tyr216 promotes phosphorylation of tau at residues such as Ser396. Insulin also increases pGSK3β-Ser9 to limit phosphorylation of tau. Deficient insulin signaling has been proposed to reduce pGSK3β-Ser9 and promote pathological excess ptau-Ser396. However, studies of these pathways in rodent models of MetS report both elevated and reduced expression of pAkt-Ser473 and pGSK3β-Ser9, raising the question of the predictive value and role of altered pGSK3β-Ser9 expression in producing excess ptau. Studies reporting reduced pGSK3β-Ser9 in insulin resistant and diabetic rodents often used fasted animals for tissue collection, but other studies without reported fasting showed increased pGSK3β-Ser9. However, elevated ptau was consistently observed under both conditions. Because short-term changes in insulin and glucose alter pAkt-Ser473 and pGSK3β-Ser9 expression, we hypothesized that phosphorylation was related to the feeding status at time of tissue collection rather than the chronic disease state, and excess ptau was resistant to these short-term changes. We examined whether fasting altered pAkt-Ser473, pGSK3β-Tyr216, and pGSK3β-Ser9, and ptau-Ser396 levels in 18-week-old male obese (OZR) and lean (LZR) Zucker rats. After measurement of blood glucose by tail sample in their home cage, fasted (16 hours) and non-fasted rats were euthanized for tissue collection. Though baseline glucose was higher in OZRs vs. LZRs in the fed state (202.4±21.9 vs. 115.9±2.7 mg/dl, t-test) and fasted state (169.4±5.8 vs. 95.3±3.8 mg/dl, t-test), fasting significantly reduced glucose in OZRs but not LZRs (2-way ANOVA with Tukey’s post hoc, P=0.023 for OZRs and P=0.143 for LZRs, n=5-8/group). Protein expression in the cerebral cortex was measured by Western blotting and normalized to actin (n=3-5 for all groups). Expression of ptau-Ser396/total tau was significantly elevated in OZRs vs. LZRs in both feeding conditions (p<0.001) and was not altered by fasting in either phenotype. Expression of pAkt-Ser476 was elevated in non-fasted OZRs vs. LZRs (p<0.001). Fasting greatly reduced pAkt-Ser476 in OZRs (p<0.001) but not LZRs (P=0.741), making expression in fasted OZRs and LZRs comparable (P=0.674). Expression of pGSK3β-Ser9 was significantly elevated in fed OZRs vs. LZRs (p<0.001). Fasting reduced expression of pGSK3β-Ser9 only in OZRs (p<0.001 in OZRs, P=0.952 in LZRs), but expression of was still elevated in fasted OZRs vs. LZRs (P=0.009). Expression of pGSK3β-Tyr216 was significantly elevated in fed OZRs vs. LZRs (p<0.001) but significantly lower in fasted OZRs vs. LZRs (p<0.001). These data show that feeding status does not alter the ptau-Ser396 in the cerebral cortex of OZRs vs. LZRs, but phosphorylation of the enzymes of the PI3K/Akt/GSK3β signaling pathway are greatly affected by MetS and feeding status at time of tissue collection. Thus, when OZRs have access to food, elevated pGSK3β-Tyr216 may contribute to the GSK3β-mediated rise in ptau-Ser396 despite elevated pGSK3β-Ser9. Supported by R01Hl132568S1, JES Edwards Foundation, and Summerfield G. Roberts Foundation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Is the Zucker Diabetic Fat Rat an Appropriate Model of Diabetic Kidney Disease: A Discussion on Hydronephrosis

Introduction: Kidney disease is a significant concern for global healthcare, particularly in individuals with diabetes. Experimental research into the pathology of diabetes is dependent on the utilisation of appropriate animal models. The Zucker Diabetic Fat (ZDF) rat has a Leptin receptor deficiency and is a commonly used model of type 2 diabetes. Here, we examine the relevance of this model for the investigation of diabetic kidney disease, with a particular focus on vascular imaging. The Zucker Lean (ZL) rat is a non-diabetic strain of the same rat lineage and will be used as a control. Method: This dataset used the ZDF rat (n=13) and the Zucker Lean (ZL) rat (n=16). Individuals were scanned at ages of 12 weeks (ZDF n=4, ZL n=4), 22 weeks (ZDF n=4, ZL n=5), and 40 weeks (ZDF n=5, ZL n=7). During open laparotomy, rats were maintained on a respirator under general anaesthesia via isoflurane and blood pressure was monitored via a central catheter. During surgery, a blood glucose measurement was taken from the tail vein and samples of arterial blood and urine were collected. The contrast medium Microfil (MV122, Flow Tech Inc., Carver, MA) was injected post-mortem via the renal artery and excised kidneys were scanned for 11 hours in a ZEISS XRadia 410 Versa μCT scanner (Carl Zeiss Microscopy GmbH, Jena, Germany). Results: As expected, the ZDF rats developed significant hyperglycaemia from 12 weeks, significant increases in albumin creatinine ratio (ACR) from 22 weeks, and a significant decrease in glomerular filtration rate (GFR) from 40 weeks. Concurrent hydronephrosis affecting more than 10% of total kidney volume was detected in 51% of all rats (group prevalence rates were ZDF=69% and ZL=38%). The percent of the kidney mass affected by hydronephrosis was significantly higher in ZDF than ZL (ANOVA row factor p=0,029*). Age had no significant impact on the size of the hydronephrotic cavity. There was a significant correlation between the degree of hyperglycaemia and the size of the hydronephrotic cavity (mm) (r=0.57, p=0,0014**). ACR, GFR and urine excretion rate were unaffected by hydronephrosis. Hydronephrosis did not have a significant impact on vascular density in the remaining kidney tissue (p=0.53). Conclusion: The high prevalence of hydronephrosis development in the ZDF rat questions its appropriateness to model human diabetic kidney disease, as hydronephrosis is not commonly seen in diabetic patients. While vascular density was preserved in the remaining kidney tissue, the huge loss of vascular tissue caused by hydronephrotic erosion means this model is limited for all renal imaging applications. Both ZDF and ZL rats develop hydronephrosis suggesting this may be a genetic condition of their common lineage. However, the conditions' increased severity in the ZDF rat indicates that the deficit in the leptin receptor contributes to disease pathology. The significant relationship between hyperglycaemia and hydronephrosis size suggests the two conditions are interacting, raising questions about whether the underlying molecular mechanisms of this model of diabetic kidney disease have any relevance for translational research. Funded by European Research Council Synergy grant SURE, project no. 854796. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.