Institute of Hydrobiology, Chinese Academy Of Sciences
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Nano-TiO2 enhanced bioaccumulation and developmental neurotoxicity of bisphenol a in zebrafish larvae
No full textThe titanium dioxide nanoparticles (n-TiO2) could enhance the bioavailability and toxicity of the coexisted organic toxicants in aquatic phase. Parental co-exposure to n-TiO2 and bisphenol A (BPA) could generate developmental neurotoxicity in unexposed zebrafish offspring. However, it remains unexplored regarding the developmental neurotoxicity in larvae fish after co-exposure during the early developmental stage. In present study, fertilized zebrafish eggs were exposed to TiO2 nanoparticles (100 mu g/L), BPA (1, 4 and 20 mu g/L) or their binary mixtures until 6 days post fertilization (dpf). No significant change was observed in hatching, malformation, survival and weight of the larvae among all groups. However, n-TiO2 significantly increased the body burden of BPA in the 4 and 20 mu g/L co-exposure groups, depressed expression of neurodevelopment marker genes (al-tubulin, mbp and syn2a) as well as the locomotor behavior. The current results indicate that n-TiO2 could strengthen the developmental neurotoxicity and inactive locomotion in co-exposed zebrafish larvae by promoting the bioaccumulation and bioavailability of BPA, which highlighted the similar toxic risks of developmental neurotoxicity after co-exposure at early developmental stage to that of the parental co-exposure
Pelagic-benthic resource polymorphism inSchizopygopsis thermalisHerzenstein 1891 (Pisces, Cyprinidae) in a headwater lake in the Salween River system on the Tibetan Plateau
No full textResource polymorphism is a ubiquitous phenomenon in vertebrates and may represent a critical intermediate stage in speciation. Freshwater lakes in high-altitude areas represent a natural system for understanding resource polymorphism in fishes benefiting from diverse lacustrine environments and species-poor fish assemblages. We report resource polymorphism in a cyprinid fish,Schizopygopsis thermalis, in Lake Amdo Tsonak Co, a headwater lake in the upper Salween River system. Two discrete intraspecific morphs, planktivorous and benthivorous, were identified according to geometric morphometrics and traditional univariate linear measures. The planktivorous morph exhibits a longer head, longer upper and lower jaw, larger asymptotic standard length (L-infinity), lower growth rate (k), and higher growth performance index (phi) than the benthivorous morph. With respect to descriptive traits, the planktivorous morph possesses a large, terminal mouth and obvious mucus pores on the cheek and chin, while the benthivorous morph is characterized by a more inferior mouth with a sharpen horny edge on the lower jaw and unconspicuous mucus pores. The discrete pelagic-benthic resources and low interspecific competition in the lake system might drive the initial differentiation of the two morphs, and partial spatial reproductive isolation in breeding further maintains and reinforces the differences between them
In Situ Assessment of Donghu Lake China Using Rare Minnow (Gobiocypris rarus)
No full textIn this work, rare minnow (Gobiocypris rarus) was applied as a sentinel organism and set in cages at control and test sampling sites in Donghu Lake for 4 weeks in March, June, September, and December 2016 to assess the biological toxicity of in situ water. Sampling for active biomonitoring and physicochemical variables was performed weekly. The control was obtained from the outdoor pool of the Institute of Hydrobiology, China. Superoxide dismutase, lipoperoxidation, metallothioneins, acetylcholinesterase activity, and Vtg mRNA expression were determined as biomarkers during the field exposure period. Survival and growth also were monitored to evaluate the overall physiological condition of the fish. The seasonal changes of organic pollutants and trace metals (As, Hg, Cr, Cu, Zn, Cd, Pb) in surface water were determined. The integrated biomarker response (IBR) index was applied to summarize biomarker responses and correlate stress levels with concentrations of organic pollutants and trace metals in the surface water. Results indicated that complex pollution by persistent organic pollutants and heavy metals was present in Donghu Lake and that the in situ exposed organisms were stressed. Moreover, the complex pollution of Donghu Lake in summer and autumn was more serious than that in spring and winter. Active biomonitoring combined with IBR analysis enabled good discrimination among different exposure seasons. The proposed protocol with caged rare minnow revealed marked biological effects caused by the investigated Lake and a useful approach that can easily be extended to monitor water pollution
Effects of plant on denitrification pathways in integrated vertical-flow constructed wetland treating swine wastewater
No full textPlant is an important part of constructed wetland (CW), while, its potential effect on nitrogen cycling is complicated. Herein, integrated vertical-flow constructed wetland (IVCW) in pilot-scale planted with Arundo donax (Planted System, PS) was constructed to treat swine wastewater. The removal performance of nitrogen in PS, effects of plant on the microbial community structure and nitrogen related function genes were revealed. Results showed that, Arundo donax planting enhanced the removal rate of TN, compared to unplanted IVCWs, the absolute abundance of Pseudomonas, Acinetobacter and Bacillus in PS was significantly increased, as well as the absolute abundance of functional gene (amoA, nxrA, nirK, nirS and nosZ). The denitrification process was mainly occurred in down-flow cell of PS with significantly higher abundant of nirK and nosZ (P < 0.05). These findings suggested that Arundo donax planting in IVCWs with zeolite as substrate promoted the growth of denitrifying microorganisms under higher pollutant load. In addition, the increased abundant of nosZ and the ratio of nosZ/Sigma nir indicating a lower genetic potential for N2O release. Our research provides new insight into the potential application of plant on the purification of swine wastewater
Hyperandrogenism in POMCa-deficient zebrafish enhances somatic growth without increasing adiposity
No full textThe endocrine regulatory roles of the hypothalamic-pituitary-adrenocortical axis on anxiety-like behavior and metabolic status have been found throughout animal taxa. However, the precise effects of the balancing adrenal corticosteroid biosynthesis under the influence of adrenocorticotrophic hormone (ACTH), a pro-opiomelanocortin (POMC)-derived peptide, on animal energy expenditure and somatic growth remain unknown. POMC has also been identified as one of the candidate loci for polycystic ovary syndrome, which features hyperandrogenism and some prevalence of obesity in patients. Here we show that zebrafish lacking functional POMCa exhibit similar phenotypes of stress response and body weight gain but not obesity as observed in mammalian models. In contrast with the impaired anorexigenic signaling cascade of melanocyte-stimulating hormones and leptin, which are responsible for their obesity-prone weight gain observed in various pomc mutant mammals, analyses with our pomca mutant series indicate that ACTH is the key regulator for the phenotype with enhanced somatic growth without obesity in pomca-deficient zebrafish. Hypocortisolism associated with hyperandrogenism has been observed in the pomca-deficient zebrafish, with enhanced activation of mammalian target of rapamycin complex 1; reutilization of amino acids and fatty acid beta-oxidation are observed in the muscle tissue of the pomca-deficient fish. After reducing hyperandrogenism by crossing our pomca mutant fish with a cyp17a1-deficient background, the phenotype of enhanced somatic growth in pomca-deficient fish was no longer observed. Thus, our work also demonstrated that the role of POMCa in stress response seems to be conserved in vertebrates, whereas its effect on adipostasis is unique to teleosts
Genetic diversity and reproductive success of a wild population of Chinese sturgeon (Acipenser sinensis) from the Yangtze River inferred from juveniles born in 2014
No full textThe Chinese sturgeon (Acipenser sinensis Gray, 1835) is a large anadromous fish species, which is under considerable threat due to dramatic declines in population numbers. In the current study, population genetic diversity and individual reproductive success were assessed using nuclear microsatellite markers (simple sequence repeat, SSR) and complete mitochondrial (mtDNA) genome analysis of juveniles born in 2014. Results showed the existence of size polymorphism in the mtDNA genome of Chinese sturgeon, which was caused by a repeat motif. Population genetic diversity was high based on both SSR (Ho: 0.728 +/- 0.211; He: 0.779 +/- 0.122) and mtDNA genome analyses (H: 0.876 +/- 0.003 5; Pi: 0.001 1 +/- 0.001 0). A positive inbreeding coefficient (FIS: 0.066 +/- 0.143) was also found, indicating the occurrence of inbreeding. Reconstruction of sibling groups identified 11 mothers and 11 fathers involved in reproduction of Chinese sturgeons in 2014. Variance in individual reproductive success was not significant, with reproductive success of parent fish instead shown to be relatively even (P=0.997>0.05), thus suggesting the absence of sweepstakes reproductive success (SRS). These results indicate that, in regard to conservation, loss of genetic diversity due to the effects of SRS is not of particular concern. However, we must focus on having an adequate number of adults and suitable environmental conditions to ensure that fish can reproduce
Influence of hydropower stations on the water microbiota in the downstream of Jinsha River, China
No full textConstruction of hydropower stations has been an important approach to meet China's increasing power demand, but the impact of construction of hydropower stations on river microbiota is not fully understood. To evaluate this, the microbial composition from 18 sampling sites in the downstream of Jinsha River of China, upstream and downstream of two completed and two under-construction hydropower stations, were analyzed using high-throughput 16S rRNA gene sequencing. Three independent samples from each site were analyzed. A total of 18,683 OTUs from 1,350 genera were identified at 97% sequence similarity. Our results showed that the completion of hydropower stations would significantly increase the relative abundances of Acidobacteria, Chlorobi, Chloroflexi, Cyanobacteria, Nitrospirae, and Planctomycetes, especially the relative abundance of Synechococcus dOTUs and thus increase the risk of algal blooms. PCA based on all KEGG pathways and the significantly different KEGG pathways showed the predicted metabolic characteristics of the water microbiota by PICRUSt in the activated hydropower station group were significant difference to the other groups. Results from canonical correspondence analysis showed that water temperature and dissolved oxygen had significant effects on microbiota composition. These results are important for assessing the impact of hydropower stations on river microbiota and their potential environmental risks
Kisspeptin2 regulates hormone expression in female zebrafish (Danio rerio) pituitary
No full textKisspeptin2 is a neuropeptide widely found in the brain and multiple peripheral tissues in the zebrafish. The pituitary is the center of synthesis and secretes various endocrine hormones. However, Kiss2 innervation in the zebrafish pituitary is unknown. In this study, the organization of Kiss2 cells and structures in the zebrafish pituitary by promoter-driving mCherry-labeling Kiss2 neurons were investigated. Kiss2 neurons in the hypothalamus do not project into the pituitary. Kiss2 cells are found in the female pituitary. Unidentified Kiss2 cells and extensions are located in the proximal pars distalis (PPD), similar to the distribution of Gnrh3 fibers. Kiss2 structures reside alongside Gnrh3 fibers. No Kiss2 structures are found in the male pituitary. The transcriptional expression of the kisspeptin receptor kiss1rb is detected in both female and male pituitaries. In situ hybridization shows that kiss1rb-positive cells are located in the PPD and pars intermedia (PI). In vitro Kiss2-10 treatment stimulates Akt and Erk phosphorylation and significantly induces lh beta, fsh beta, and prl1 mRNA expression in the female pituitary. The results in this study suggest that Kiss2 and Kiss1rb may form an independent paracrine or autocrine system in the female zebrafish pituitary. Kiss2 and Kiss1rb signaling regulates the expression of pituitary hormones
Nonlinear response of methane release to increased trophic state levels coupled with microbial processes in shallow lakes
No full textShallow lakes are a crucial source of methane (CH4), a potent greenhouse gas, to the atmosphere. However, large uncertainties still exist regarding the response of CH4 emissions to the increasing trophic levels of lakes as well as the underlying mechanisms. Here, we investigate the CH4 emission flux from lakes with different trophic states in the middle and lower reaches of the Yangtze River basin, China to evaluate the effect of the trophic lake index (TLI) on CH4 emissions. The mean CH4 emission fluxes from mesotrophic, eutrophic, middle-eutrophic, and hyper-eutrophic lakes were 0.1, 4.4, 12.0, and 130.4 mg m(-2) h(-1), respectively. Thus, the CH4 emission flux ranged widely and was positively correlated with the degree of eutrophication. The relative abundance of methanogens with respect to the total population for the mesotrophic, eutrophic, mid-eutrophic, and hyper-eutrophic states was 0.03%, 0.35%, 0.94%, and 1.17%, respectively. The biogeographic-scale pattern of lakes classified as each of these four trophic states indicated that CH4 emissions could be well-predicted by the NH4+-N concentration in the water column, as both NH4+-N and CH4 were produced during mineralisation of labile organic matter in lake sediment. In addition, the shift from clear to turbid water, which is an unhealthy evolution for lakes, was associated with a nonlinear increase in the CH4 emissions from the studied lakes. In particular, the hypereutrophic lakes functioned as CH4 emission hotspots. Our findings highlight that nutrient levels, as a potential facilitator of CH4 emissions, should be considered in future research to accurately evaluate the greenhouse gas emissions from shallow lakes. (C) 2020 Elsevier Ltd. All rights reserved
Assessing the intestinal bacterial community of farmed Nile tilapia (Oreochromis niloticus) by high-throughput absolute abundance quantification
No full textIntestinal microbiota studies based on high-throughput sequencing have attracted increasing attention due to its vital impact on host health. However, the taxonomical profile in relative proportion does not reflect the quantity of the intestinal bacteria and the inter-sample differences among taxa. In this study, we applied a high-throughput absolute abundance quantification method that used an internal standard strain to simultaneously obtain both the relative and absolute abundances in the intestinal bacterial community of farmed Nile tilapia (Oreochromis niloticus). The results showed that the structure, relative and absolute abundances, and function of the intestinal indigenous microbiota didn't change significantly after adding a low concentration of internal standard strain, and a comprehensive quantitative intestinal bacterial ecology was obtained. We first found that the total absolute abundance of the intestinal indigenous bacteria in farmed Nile tilapia was 2.95 x 10(8) cells g(-1), and most genera concentrations were in the range of 10(3) to 10(5) cells g(-1). The intestinal bacterial community was dominated by Cetobacterium with a concentration of 10(8) cells g(-1), followed by Plesiomonas, Romboutsia, and Escherichia-Shigella with concentrations of over 10(7) cells g(-1). The potential intestinal pathogens Aeromonas and Streptococcus reached 10(5) cells g(-1) in the tilapia intestines, while the potential probiotics such as Lactobacillus and Enterococcus with a high concentration of over 10(6) cells g(-1) were detected. Furthermore, PICRUSt analysis revealed that functional genes involved in membrane transport, carbohydrate metabolism, and amino acid metabolism were enriched in the intestinal microbiota of tilapia. This study characterized the intestinal quantitative bacterial ecology of farmed Nile tilapia, providing foundational support for an in-depth understanding of the intestinal microbiota and its interaction mechanism with the host