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The PIESAT-01 constellation is the world's first multi-baseline distributed synthetic aperture radar (SAR) constellation with a "Cartwheel" formation. The "Cartwheel" formation is a unique formation in which four satellites fly in companion orbits, ensuring that at any given moment, the main satellite remains at the center, with three auxiliary satellites orbiting around it. Due to this unique configuration of the PIESAT-01 constellation, four images of the same region and six pairs of baselines can be obtained with each shot. So far, there has been no imaging and interference research based on four-satellite constellation measured data, and there is an urgent need to explore algorithms for the "Cartwheel" configuration imaging and digital surface model (DSM) production. This paper introduces an improved bistatic SAR imaging algorithm under the four-satellites interferometric mode, which solves the problem of multi-orbit nonparallelism in imaging while ensuring imaging coherence and focusing ability. Subsequently, it presents an interferometric processing method for the six pairs of baselines, weighted fusion based on elevation ambiguity from different baselines, to obtain a high-precision DSM. Finally, this paper selects the Dingxi region of China and other regions with diverse terrains for imaging and DSM production and compares the DSM results with ICESat-2 global geolocated photon data and TanDEM DSM data. The results indicate that the accuracy of PIESAT-01 DSM meets the standards of China's 1:50,000 scale and HRTI-3, demonstrating a high level of precision. Moreover, PIESAT-01 data alleviate the reliance on simulated data for research on multi-baseline imaging and multi-baseline phase unwrapping algorithms and can provide more effective and realistic measured data. [ABSTRACT FROM AUTHOR]

In this study, we examine the relationship between value-added tax burden and export quality. Our results show that the increase of VAT burden leads to lower export quality. We also find that the decline in export quality may be caused by the decrease of product innovation. Moreover, the empirical evidence on patent application shows that VAT burden mainly reduces invention and utility model patents, instead of design patents. [ABSTRACT FROM AUTHOR]

In this article, we explored Hui students' lived experiences in school in eastern China and the impact of their experiences on their identity construction. We used postcolonial theory as a theoretical framework and narrative inquiry as a research methodology to guide questions that we asked, data collection, data analysis, and interpretation and discussion of the findings in the study. We found that schooling for the two Hui students in eastern China is a process of reproducing mainstream Han ideology; taking away their culture, beliefs, knowledge, and identity; and imposing the mainstream Han culture and knowledge on Hui students as truth. The participants, two Hui students in an elementary school in eastern China, accepted the identity constructed by mainstream Han teachers and were confused about their Hui identity.

The escalation in carbon dioxide concentration has precipitated global climate warming, accentuating ecological and environmental concerns. Notably, China stands as the world's largest carbon emitter, with the Taihu Lake basin emerging as a carbon-intensive region within the country. This paper undertakes a comprehensive analysis spanning 2005 to 2020, calculating the economic contribution coefficient of carbon emissions and the ecological carrying coefficient of carbon absorption in the Taihu Lake basin. The study includes a delineation of carbon balance zones and an exploration of the geographical and spatial influences of both ecosystem and economic factors. The overarching trend in carbon emissions within the Taihu Lake Basin initially exhibited rapid growth, followed by a fluctuating decline, with the pivotal year being 2012, recording the apex of emissions at 575.8293 million tons. Concurrently, total carbon absorption demonstrated a fluctuating growth trajectory, ascending from 82.3503 million tons in 2005 to 85.6488 million tons in 2020. The carbon emission intensity in the basin manifested a pattern of high concentration in the northeast and low concentration in the southwest, while the carbon absorption intensity displayed the inverse pattern. The carbon balance across the Taihu Lake Basin revealed a spatial incongruity, characterized by a suboptimal pattern in the northeast and a favorable pattern in the southwest. Zhejiang Province emerged as an ecological stronghold within the basin, acting as the primary carbon sink functional area. Urban built-up areas and forested regions emerged as principal influencers of carbon balance in the Taihu Lake basin. Urban construction land, population density, and arable land area were identified as primary contributors to carbon emissions, whereas per capita GDP, forests, grasslands, and water bodies were identified as main contributors to carbon absorption in the watershed. [ABSTRACT FROM AUTHOR]

Simple Summary: Lindian chickens are a local chicken variety in northern China. To explore the growth and development characteristics of Lindian chickens, various statistical methods were used to analyze their body size and carcass traits. The results showed that multiple trait measurements of Lindian chickens rapidly increased before 10 weeks of age, while after 19 weeks of age they mainly developed reproductive organs and muscles. In addition, we also found that body size traits were closely related to carcass traits, providing a foundation for the breeding and management of Lindian chickens. As an excellent chicken breed found in a high-altitude zone of northern China, Lindian chickens are characterized by good egg and meat production, strong adaptability, cold tolerance, rough feeding resistance, excellent egg quality, and delicious meat quality. To facilitate the exploitation of the unique qualities of the Lindian chicken, the varying patterns and correlations of various body size and carcass traits of 3–22-week-old Lindian chickens were analyzed in this study. The optimal growth model of these traits was determined by growth curve fitting analysis. The results showed that most traits of Lindian chickens increased steadily with increasing age, and most of them increased rapidly before 10 weeks of age. In addition, the inflection point age of each trait was predicted to be between 4 and 10 weeks. Furthermore, this study revealed that body size traits were closely related to carcass traits in Lindian chickens. In summary, Lindian chickens are in a rapid growth stage before the age of 10 weeks, and better slaughter performance can be achieved through good feeding management during this stage. The reproductive traits and muscles are the main developmental focus after the age of 19 weeks, so it is important to adequately meet their energy requirements for subsequent good breeding performance. [ABSTRACT FROM AUTHOR]

In this study, we examine the impact of migration experience on return migrant's social capital using household survey data from rural China. We first develop a simple model to describe rural household's decision to invest in social capital and then empirically examine how migration experience affects social capital using village-level natural disasters as instrumental variables for migration experience. Our results show that villagers' migration experience reduces both structural social capital and cognitive social capital. Compared with those who never worked out of their native villages, return migrants would practice fewer social interactions, information communication, trust building and reciprocal behaviours with relatives. We provide suggestive evidence that the decline in social capital may be caused by the higher expected mobility of return migrants. [ABSTRACT FROM AUTHOR]

This study critically examines knowledge in elementary school textbooks in China. Language analysis and story-line analysis are used to examine how the knowledge related to minority groups and how the knowledge related to the Han group are introduced and interpreted. This study finds that the Han knowledge dominates elementary school textbooks in China and that minority knowledge and culture are under-represented, which demonstrates that the dominant Han group's knowledge is seen as the "truth" while minority knowledge is seen as backward. Moreover, through the dominant Han group's selection and construction of school knowledge, the Han group reproduces its ideology and legitimates its hegemonic control over minority groups. Minority knowledge and culture are, therefore, subjugated. (Contains 1 note.)

Esophageal squamous cell carcinoma (ESCC) is the most common pathological type of esophageal cancer in China. Patients with ESCC have poor long-term survival, especially those with lymphatic metastasis (pN + ESCC). In this retrospective study, we evaluated the correlates of long-term survival time of patients with pN + ESCC. A total of 453 patients with pN + ESCC who underwent surgical R0 resection between Jan 2008 and Sep 2011 were enrolled. The follow-up ended on December 2019. The clinical, pathological, inflammation-related factors and general survival data of these patients were analyzed using SPSS 22.0 software. The 1-, 3-, and 5-year overall survival (OS) rates were 73.7%, 34.6%, and 25.6%, respectively; the 1-, 3-, and 5-year disease-free survival (DFS) rates were 45.0%, 26.3%, and 20.4%, respectively. The median OS and DFS were 23 and 14 months, respectively. On multivariate analyses, gender, site of lesion, number of dissected lymph nodes, stage pTNM, adjuvant therapy, and neutrophil lymphocyte ratio were independent predictors of OS. Site of lesion, stage pTNM, and adjuvant therapy were independent predictors of DFS. Recursive partitioning analysis (RPA) scores of each patient were calculated based on the independent predictors of OS, and the patients were divided into 3 classes: low-risk, medium-risk, and high-risk. The OS, DFS, and local recurrence-free survival were significantly different among these three RPA classes P < 0.001 . Several factors showed an independent association with long-term postoperative survival of pN + ESCC patients after radical surgery. RPA scores can potentially be used to predict the prognosis of ESCC. [ABSTRACT FROM AUTHOR]

Esophageal squamous cell carcinoma (ESCC) is the most common pathological type of esophageal cancer in China. However, patient survival time after surgery remains unsatisfactory, especially in those who are pN+. This retrospective study determined the value of postoperative adjuvant therapy for patients with pN+ ESCC. From Jan 2008 to Sep 2011, 453 pN+ ESCC patients who underwent R0 resection and survived for at least 1 month were retrospectively enrolled. All patients received surgery. Some patients received surgery alone (SA, n = 131), and others received postoperative chemotherapy (POCT, n = 222), radiotherapy (PORT, n = 57), or sequential chemoradiotherapy (POCRT, n = 43). The follow-up ended on 1 Dec 2019. The 5-year overall survival (OS), disease-free survival (DFS), and locoregional recurrence (LR) were significantly worse in the SA group (15.2%, 13.1%, and 71.6%, all p < 0.05) than in the POCT group (28.0%, 20.8%, and 66.5%), the PORT group (27.4%, 24.4%, and 46.9%), and the POCRT group (42.8%, 35.5%, and 43.0%). Furthermore, compared with the SA group, the median OS and DFS were significantly longer in the POCT, PORT, and POCRT groups (all p < 0.05). PORT and POCRT (but not POCT) also significantly reduced the LR (p < 0.01). Multivariate Cox analysis showed that each type of postoperative therapy was independently associated with improvements in OS, DFS, and LR. Postoperative adjuvant therapy—either POCT, PORT, or POCRT—significantly improved OS and DFS in patients with pN+ ESCC after R0 surgery. PORT and PORCT significantly reduced LR in these patients. [ABSTRACT FROM AUTHOR]

aim of this study was to assess active tuberculosis-related deaths in Shenzhen city of China to identify major causes of mortality in different age groups. Patients and Methods: Medical records of mortality cases of patients with active TB diagnosed during 2013– 2018 were reviewed. All TB deaths were classified into two broad age groups (the young group: 18– 65 years old and the elderly group: > 65 years old). Causes of death were analyzed based on medical records. Results: A total of 279 mortality cases of active TB were reviewed during the study period. Among them, mean age was 54.0± 20.5 years old; 80.6% (225/279) were male. There were 5.7% and 4.6% MDR/XDRTB patients in the young and elderly group. Newly treated TB accounted for 89.6% in the young group and 85.1% in the elderly group. Pulmonary TB was a major infection type in both groups (65.1% vs 77.0%). Advanced TB (23.4%) and HIV co-infection (20.8%) were the leading causes of deaths in the young group, but deaths in the elderly group were mostly associated with underlying diseases, including cardiovascular disease (52.9%), diabetes (33.3%), COPD (16.1%) and cancer (11.5%). Malnutrition was a significant condition in both groups (43.2% vs 35.6%). In terms of respiratory complications, bacterial infection was the leading comorbidity in both groups (27.1% vs 18.4%), followed by septic shock (18.2% vs 12.6%) and respiratory failure (12.0% vs 11.5%). There were no significant statistical differences between the two groups. Conclusion: Our findings suggest that screening for HIV co-infection and early diagnosis of TB is vital in lowering TB-related deaths in young patients. Most deaths in elderly TB patients were caused by underlying health conditions or complications other than TB. [ABSTRACT FROM AUTHOR]

Little is known about mercury (Hg) biomagnification in the subtropics, aquatic systems with high species diversity resulting in complex food webs. High atmospheric Hg emissions and ubiquitous reservoir fisheries may lead to elevated Hg bioaccumulation in Chinese freshwater fishes. However, stocking practices using fast-growing species can result in low fish total Hg (THg) concentrations. Here, we describe Hg transfer within the fish food web of a large subtropical reservoir, Qiandao Hu (Xin'anjiang reservoir) situated in eastern China. We measured food web Hg biomagnification and THg concentrations in 33 species of stocked and wild fishes. Mercury concentrations in most fishes were low, though we also found high Hg concentrations in wild top predators. The food web structure, assessed using stable isotopes of carbon (δC) and nitrogen (δN), demonstrated a high degree of omnivory and a long food chain. THg concentrations were highly correlated with fish δN values. The regression of logTHg against δN revealed the overall Hg biomagnification rate was low. This study shows that where long food chains exist in subtropical reservoirs, elevated Hg accumulation in top predators can occur despite a low Hg biomagnification rate. [ABSTRACT FROM AUTHOR]

Drought is the most challenging environmental stress factor for grassland ecosystems as the climate change. Seriphidium transiliense , a typical plant in the desert steppe, is widely distributed in northern Xinjiang Region of China. In this study, we analyzed the phenotypic traits, physiological responses, and transcriptional changes in the leaves and roots of S. transiliense , exposed to different levels of drought stress. The morphology of the aboveground and underground portions of S. transiliense changed significantly under drought stress. Additionally, the antioxidants activity and content in leaves and roots increased dramatically. Based on the weighted gene co-expression network analysis (WGCNA) method, we performed a correlation analysis between physiological traits and differentially expressed genes (DEGs) to characterize the key genes and regulatory pathways involved in drought resistance in S. transiliense. A total of 135 and 120 DEGs associated with drought resistance were identified in leaves and roots, respectively. These genes included 38 responsive transcription factors (TFs) belonging to WRKY, AP2/ERF, C2H2, bHLH, MYB, bZIP, NAC, LEA, MADS, and GRAS families that play critical roles in plant responses to abiotic stresses. Furthermore, many receptor protein kinase encoding genes including CBL , CIPK , LRR-RLK , CRK , PI3K , CML , and PP2C involved in the stress signaling responses such as ABA signaling pathway, MAPK signaling pathway, and Ca2+ signal transduction, were significantly upregulated under different levels of drought stresses. Moreover, more responsive genes participated in multiple carbohydrate metabolic pathways in roots. Our study provided new insights into the regulatory mechanism of the acclimation responses to drought stress in S. transiliense and suggested that these genes may be used in molecular breeding to develop new varieties tolerant to drought stress. • Phenotypic and physiological characteristics of S. transiliense changed significantly under drought stress. • Many receptor protein kinases and Ca2+-binding proteins were involved in drought stress responses. • More responsive genes in roots participated in multiple carbohydrate metabolisms. [ABSTRACT FROM AUTHOR]

Objectives: The incidence of Helicobacter pylori (HP) is 25-50% in developed countries and 80% in developing countries, including 56.2% in China. However, antibiotic resistance of HP is a threat to HP control. The purpose of this study was to comprehensively evaluate primary drug resistance of HP in China., Methods: The full text of reports of the primary antibiotic resistance prevalence of HP was obtained from multiple databases (PubMed, Web of Science, Evimed, Cochrane Library, and China National Knowledge Internet). Review Manager 5.2 was adopted for meta-analysis, sensitivity analysis, and bias analysis. The Newcastle-Ottawa Scale was used to assess the article quality., Results: In total, 38804 HP samples from 22 trials were extracted. The results suggested that the overall prevalence of amoxicillin, clarithromycin, metronidazole, and levofloxacin resistance among HP in adults was as follows: mean difference (MD) = 1.35%, 95% confidence interval (CI) [1.03%, 1.68%]; MD = 23.76%, 95% CI [20.23%, 27.3%]; MD = 69.32%, 95% CI [64.85%, 73.8%]; and MD = 29.45%, 95% CI [4.90, 176.96], respectively. From the results of sensitivity and publication bias, we find that these results are robust and had little publication bias., Conclusion: Our research showed that in China, the prevalence of HP resistance to primary antibiotics warrants attention, especially with regard to metronidazole, levofloxacin, and clarithromycin., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Although several traditional Chinese medicine (TCM)-related databases have emerged, they focus on researching single medicinal materials, which is far from sufficient for clinical research and application. In comparison, compound prescriptions are more informative and meaningful in TCM, for they embody the information on the compatibility of TCM besides the relatively isolated information about single medicinal materials. The compatibility information is essential in TCM because it conveys not only what components are involved to treat special diseases but also how to combine these single medical materials. We established a database of Chinese patent medicine and compound prescription (CPMCP). It demonstrates the prescription information of Chinese patent medicines (CPMs) and ancient Chinese medicine prescriptions (CMPs). CPMCP reports their comprehensive and standardized information such as the components, indications and contraindications. It is worth mentioning that we organized relevant experts and spent lots of time manually mapping the functions of compound prescriptions in ancient Chinese to the standardized TCM symptom vocabularies, obtaining a total of 71 414 associations between compound prescriptions and TCM symptoms. In this way, CPMCP established the associations between TCM and modern medicine (MM) according to the associations between TCM symptoms and MM symptoms. In addition, to further exhibit the compatibility mechanism of compound prescriptions, CPMCP summarizes a set of common drug combination principles by analyzing the existing prescriptions. We believe that CPMCP can promote the modernization of TCM and make greater contributions to MM. Database URL http://cpmcp.top., (© The Author(s) 2022. Published by Oxford University Press.)

Objective: The purpose of this study was to evaluate the association between triglyceride glucose (TyG) index and new-onset diabetes under different glycemic states and to compare the predictive value of TyG-related parameters, obesity indices, and lipid ratios for new-onset diabetes., Methods: Data were collected from the China Health and Retirement Longitudinal Study (CHARLS), consisting of 6,258 participants aged ≥45 years. Participants were grouped according to their glycemic states. Cox proportional hazards models and restricted cubic spline regression were used to explore the association between TyG index and diabetes. Cox proportional hazard models were applied to confirm the predictive value of the optimal marker. Receiver operating characteristic (ROC) curves were used to compare the predictive value., Results: TyG index was positively correlated with the risk of diabetes (hazard ratio (HR), 1.75; 95% confidence interval (CI), 1.56-1.97), and the linear association existed ( p  < 0.001). The highest correlation with diabetes was visceral adiposity index (VAI) (HR, 2.04; 95% CI, 1.44-2.90) in normal fasting glucose (NFG) group and TyG-body mass index (TyG-BMI) (HR, 2.53; 95% CI, 1.97-3.26) in impaired fasting glucose (IFG) group. The largest area under curve (AUC) was observed in TyG-waist-to-height ratio (TyG-WHtR) in the NFG group (AUC, 0.613; 95% CI, 0.527-0.700), and TyG-BMI had the highest AUC in the IFG group (AUC, 0.643; 95% CI, 0.601-0.685)., Conclusion: The association between TyG index and new-onset diabetes was positive and linear. TyG-WHtR was a clinically effective marker for identifying the risks of diabetes in the NFG group and TyG-BMI was an effective marker to predict diabetes in the IFG group., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Li, Sun, Yang, Yao, Yan, Wang, Hu, Guo, Wang and Li.)

Objective: Lynch syndrome (LS) predisposes patients to early onset endometrioid endometrial cancer (EEC). However, little is known about LS-related EEC in the Chinese population. The aim of this study was to investigate the prevalence of LS and to identify the specific variants of LS in Chinese patients with EEC. Methods: We applied universal immunohistochemistry screening to detect the expression of mismatch repair (MMR) proteins, which was followed by MLH1 methylation analysis to identify suspected LS cases, next-generation sequencing (NGS) to confirm LS, and microsatellite instability (MSI) analysis to verify LS. Results: We collected 211 samples with EEC. Twenty-seven (27/211, 12.8%) EEC cases had a loss of MMR protein expression. After MLH1 methylation analysis, 16 EEC cases were suggested to be associated with LS. Finally, through NGS and MSI analysis, we determined that 10 EEC (10/209, 4.78%) cases were associated with LS. Among those cases, 3 unreported mutations (1 frameshift and 2 nonsense) were identified. MSH6 c.597&#95;597delC, found in 4 patients, is likely to be a founder mutation in China. Conclusions: We demonstrated the feasibility of a process for LS screening in Chinese patients with EEC, by using universal immunohistochemistry screening followed by MLH1 methylation analysis and confirmation through NGS and MSI analysis. The novel mutations identified in this study expand knowledge of LS., (Copyright: © 2020, Cancer Biology & Medicine.)

Jujube ( Ziziphus jujuba Mill.) honey, one of the most valuable honey varieties from China with unique characteristics, is vulnerable to being the target of adulteration and deliberate mislabeling of botanical origin. This study investigated the typical protein component of jujube honey to authenticate the floral source by SDS-PAGE analysis combined with LC-MS/MS identification, and its stability to heating was also evaluated. One band and two adjacent but independent bands, both with molecular weights of ∼19 kDa, were notably observed in Coomassie brilliant blue- and silver-stained SDS-PAGE gels, respectively, for jujube honey from different geographic origins, whereas that was not present for the other five botanical honey varieties, suggesting this protein component was suitable as a marker for jujube honey. LC-MS/MS identification revealed that it was constituted by one Z. jujuba -derived protein (gene number: Zj.jz 016003045) and two A. mellifera -derived proteins (an uncharacterized protein with accession number tr|A0A088AC16 and a cleavage fragment from major royal jelly protein-1), and the existence of plant-derived protein was attributed to the special neutral pH of jujube honey. Additionally, these protein markers exhibited good stability to heating below 85 °C/30 min. This study provided a simple method to characterize jujube honey and first identified a protein indicator to determine the botanical origin of honey.

The naked carp is an endangered cyprinid that migrates annually between freshwater rivers, where it spawns, and Lake Qinghai, where it feeds and grows. Lake Qinghai is a high-altitude lake (3,200 m) in western China that currently exhibits the following composition (in mmol L(-1): [Na(+)] 200, [Cl(-)] 173, [Mg(2+)] 36, [Ca(2+)] 0.23, [K(+)] 5.3, total CO(2) 21, titration alkalinity 29; osmolality 375 mOsm kg(-1); pH 9.3), but concentrations are increasing because of water diversion and climate change. We studied the physiology of river water to lake water transfer. When river fish are transferred to lake water, there is a transitory metabolic acidosis followed by a slight respiratory alkalosis, and hemoconcentration occurs. All plasma electrolytes rise over the initial 48 h, and final levels in lake water-acclimated fish are very close to lake water concentrations for [Na(+)], [Cl(-)], [K(+)], and osmolality, whereas [Ca(2+)] continues to be regulated well above ambient levels. However, [Mg(2+)] rises to a much greater extent (fourfold in 48 h); final plasma levels in lake fish may reach 12 mmol L(-1) but are still much lower than in lake water (36 mmol L(-1)). At the same time, urine flow rate decreases drastically to <5% of river water values; only the renal excretion of Mg(2+) is maintained. Both gill and kidney Na(+),K(+)-ATPase rapidly decline, with final levels in lake water fish only 30% and 70%, respectively, of those in river water fish. Metabolic rate also quickly decreases on exposure to lake water, with O(2) consumption and ammonia-N excretion rates eventually falling to only 60% and 30%, respectively, of those in river fish, while plasma ammonia rises fivefold. The fish appear to be benefiting from a metabolic holiday at present because of decreases in iono- and osmoregulatory costs while in lake water; elevated plasma [Mg(2+)] and ammonia may be additional factors depressing metabolic rate. If the lake continues to dehydrate, these benefits may change to pathology.

The scale-less carp (Gymnocypris przewalskii) inhabits Lake Qinghai located on the Qinghai-Tibet plateau (elevation, 3200 m) in western China. The lake waters are alkaline (pH 9.4, titratable alkalinity=30 mmol l(-1)), Mg(2+)-rich (18.7 mmol l(-1)), Ca(2+)-poor (0.30 mmol l(-1)) and saline (9 per thousand ). These fish make annual spawning migrations into freshwater rivers. We investigated the physiology of nitrogen excretion and ionoregulation of fish from the lake and river. Fish from both waters were ammonotelic, although ammonia-N excretion rates were lower in lake fish (175 vs. 344 micromol kg(-1) h(-1), P<0.05) resulting in unusually high levels of ammonia in blood plasma (2.23 vs. 0.32 mmol l(-1)), bile, liver, muscle and brain. Exposure to 0.4 mmol l(-1) total ammonia in lake water ([NH(3)]=0.16 mmol l(-1)) killed fish within 8 h. River fish survived exposure to 1.0 mmol l(-1) total ammonia in river water at pH 8.0 ([NH(3)]=0.023 mmol l(-1)) for 24 h suggesting high ammonia tolerance in lake fish. High glutamate dehydrogenase and glutamine synthetase activities in tissues probably allow the fish to alleviate ammonia toxicity by amino acid accumulation. Neither lake nor river fish relied on urea excretion to remove excess N. Urea-N excretion rates were below 20 micromol kg(-1) h(-1) for both groups, and levels of urea in plasma and tissues were moderate. When exposed to elevated ammonia, urea-N excretion increased slightly (approximately 50 micromol kg(-1) h(-1)) and liver and muscle urea levels increased in the river fish. Plasma ion levels were within the range typical of cyprinids, but river fish had significantly higher plasma [Na(+)] and [Cl(-)] and lower [K(+)] than fish from the lake. During 48-h lake-to-river water transfer, plasma Na(+) and Cl(-) levels rose significantly. Significantly higher Na(+)/K(+)-ATPase activity in the gills of river fish may be related to the higher plasma ion levels. Plasma [Mg(2+)] and [Ca(2+)] were tightly regulated despite the great differences in the lake and river water levels.