| 1. |
- Gao, Hongkai, et al.
(author)
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Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections
- 2021
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 765
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Journal article (peer-reviewed)abstract
- Glacier retreat caused by global warming alters the hydrological regime and poses far-reaching challenges to water resources and nature conservation of the headwater of Yangtze River, and its vast downstream regions with dense population. However, there is still lack of a robust modeling framework of the “climate-glacier-streamflow” in this water tower region, to project the future changes of glacier mass balance, glacier geometry, and the consequent impacts on runoff. Moreover, it is imperative to use the state-of-the-art sixth phase Coupled Model Intercomparison Project (CMIP6) to assess glacio-hydrology variations in future. In this study, we coupled a glacio-hydrological model (FLEXG) with a glacier retreat method (Δh-parameterization) to simulate glacio-hydrological processes in the Dongkemadi Glacier (over 5155 m.a.s.l), which has the longest continuous glacio-hydrology observation on the headwater of Yangtze River. The FLEXG-Δh model was forced with in-situ observed meteorological data, radar ice thickness, remote sensing topography and land cover data, and validated by measured runoff. The results showed that the model was capable to simulate hydrological processes in this glacierized basin, with Kling-Gupta efficiency (IKGE) of daily runoff simulation 0.88 in calibration and 0.70 in validation. Then, forcing by the bias-corrected meteorological forcing from the eight latest CMIP6 Earth system models under two climate scenarios (RCP2.6 and RCP8.5), we assessed the impact of future climate change on glacier response and its hydrological effects. The results showed that, to the end of simulation in 2100, the volume of the Dongkemadi Glacier would continuously retreat. For the RCP2.6 and RCP8.5 scenarios, the glacier volume will decrease by 8.7 × 108 m3 (74%) and 10.8 × 108 m3 (92%) respectively in 2100. The glacier runoff will increase and reach to peak water around 2060 to 2085, after this tipping point water resources will likely decrease.
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| 2. |
- Zhang, Wei, et al.
(author)
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Methylglyoxal-hydroimidazolones (MG-Hs) instead of N epsilon-(carboxymethyl)-L-lysine (CML) is the major advanced glycation end-product during drying process in black tea
- 2020
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In: Food Chemistry. - : Elsevier. - 0308-8146 .- 1873-7072. ; 333
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Journal article (peer-reviewed)abstract
- This study was to examine the formation of advanced glycation end-products (AGEs) in black tea during drying process at 90, 120, and 150 degrees C for 1 h. Nine AGEs including N epsilon-(carboxyethyl)-L-lysine (CEL), N epsilon-(carboxymethyl)-L-lysine (CML), three isomers of methylglyoxal-hydroimidazolones (MG-Hs), three isomers of glyoxal-hydroimidazolones (GO-Hs), and argpyrimidine were quantified by using HPLC-MS/MS with isotope-labelled internal standard. Results showed that each AGE during the drying process of 150 degrees C was significantly higher (p < 0.05) than at 90 and 120 degrees C, and argpyrimidine was only found in the treatment of 150 degrees C. MG-H1/3 was first quantified as the major AGE during drying at 120- 150 degrees C, the content respectively reached to (39.66 +/- 2.61) mu g/g and (58.88 +/- 1.76) mu g/g after 1 h drying, where CML content only had (19.86 +/- 1.02) mu g/g and (23.71 +/- 1.40) mu g/g. This study indicated that arginine derived-AGEs are the key components of black tea AGEs.
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| 3. |
- Gao, Hongkai, et al.
(author)
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Fish communities and diversity in river ecosystems on the Qinghai-Tibet Plateau revealed by environmental DNA (eDNA) method
- 2023
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In: Ecological Indicators. - 1470-160X. ; 156
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Journal article (peer-reviewed)abstract
- The Qinghai-Tibet Plateau (QTP) serves as the source of many large rivers in Asia, and also serves as a natural habitat for rare wildlife and a genetic reservoir for plateau species. The exceptional ecological environment of the QTP has fostered diverse fish species. However, due to climate change and human activities, fish species in this area are facing serious threats, while large spatial scale investigation is a big challenge. Environmental DNA (eDNA) metabarcoding, as an innovative monitoring technology, offers a simple, fast, and environmentally friendly approach to explore fish communities on the QTP. This study utilized eDNA technology to assess the diversity, composition, and potential environmental influences of riverine fish communities across the QTP. A total of 90 fish species were identified belonging to 79 genera, 34 families, and 18 orders. The dominant species were Schizothorax chongi, Gymnocypris przewalskii, Carassius carassius, and Botia striata. PCoA and ADONIS indicated significant differences among fish community in different river basins of the Qinghai-Tibet Plateau. Canonical correspondence analysis (CCA) revealed that the ratio of SRP to TP, average NDVI, average elevation, and proportion of bare land significantly influenced the distribution of fish community. This study provided a novel monitoring method and insight for fish communities and implied potential species invasion on the QTP.
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| 4. |
- Ji, Jiadong, et al.
(author)
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Detection for pathway effect contributing to disease in systems epidemiology with a case-control design
- 2015
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In: BMJ Open. - : BMJ. - 2044-6055. ; 5:1, s. e006721-
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Journal article (peer-reviewed)abstract
- Objectives: Identification of pathway effects responsible for specific diseases has been one of the essential tasks in systems epidemiology. Despite some advance in procedures for distinguishing specific pathway (or network) topology between different disease status, statistical inference at a population level remains unsolved and further development is still needed. To identify the specific pathways contributing to diseases, we attempt to develop powerful statistics which can capture the complex relationship among risk factors. Setting and participants: Acute myeloid leukaemia (AML) data obtained from 133 adults (98 patients and 35 controls; 47% female). Results: Simulation studies indicated that the proposed Pathway Effect Measures (PEM) were stable; bootstrap-based methods outperformed the others, with bias-corrected bootstrap CI method having the highest power. Application to real data of AML successfully identified the specific pathway (Treg -> TGF beta -> Th17) effect contributing to AML with p values less than 0.05 under various methods and the bias-corrected bootstrap CI (-0.214 to -0.020). It demonstrated that Th17-Treg correlation balance was impaired in patients with AML, suggesting that Th17-Treg imbalance potentially plays a role in the pathogenesis of AML. Conclusions: The proposed bootstrap-based PEM are valid and powerful for detecting the specific pathway effect contributing to disease, thus potentially providing new insight into the underlying mechanisms and ways to study the disease effects of specific pathways more comprehensively.
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| 5. |
- Li, Meijun, et al.
(author)
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Identified temporal variation of soil hydraulic parameters under seasonal ecosystem change using the particle batch smoother
- 2024
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In: Geoderma. - 0016-7061 .- 1872-6259. ; 442
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Journal article (peer-reviewed)abstract
- Soil hydraulic parameters are influenced by various inherent soil properties, such as pore structure and organic matter content, which can vary with changes in the ecosystem. However, identifying the temporal variations of soil hydraulic parameters in a co-evolving soil-vegetation system remains a challenge. This study focused on a tropical forest with significant seasonal variations in vegetation attributes, evaporation, and carbon fluxes over a five-year monitoring period. The particle batch smoother algorithm was integrated with an unsaturated flow model to identify the seasonally varied soil hydraulic parameters through assimilation of in-situ measured soil moisture. As a benchmark, the Generalized Likelihood Uncertainty Estimation method was applied to optimize soil hydraulic parameters without considering temporal variation. The results indicated that the temporally varying soil hydraulic parameters exhibited regular seasonal patterns and outperformed the unvaried soil hydraulic parameters in terms of reducing the errors in modeling of soil moisture and evaporation. Moreover, the seasonal variations in soil hydraulic parameters were closely linked to changes in the litterfall and terrestrial carbon fluxes over time. Specifically, due to the hysteresis of the transformation from litterfall to soil organic matter, the accumulated litterfall in Hot-dry season can replenish the soil organic matter, resulting in an increase in field capacity and saturated hydraulic conductivity in the Hot-rainy season. However, the intense decomposition of soil organic matter under high temperature in Hot-dry season led to a decrease in field capacity and saturated hydraulic conductivity. This study emphasizes the value of the particle batch smoother algorithm in detecting temporal variations in soil hydraulic parameters within a coevolving soil-vegetation system, thereby contributing to a more comprehensive understanding of the intricate dynamics within the ecohydrological system under a changing environment.
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| 6. |
- Ni, Jingwen, et al.
(author)
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天山典型流域水文多要素模拟与气候变化影响预估
- 2023
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In: Journal of Glaciology and Geocryology. - 1000-0240. ; 45:6, s. 1875-1886
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Journal article (peer-reviewed)abstract
- Because of varied topography and landscape heterogeneity，Tianshan Mountain has extremely complex hydrological processes. Considering that the climate change poses a great threat to the water security，it’s necessary to simulate the change of water elements quantitatively and systematically along with elevation. In this study，we applied the modified FLEXG-Δh model to four classic river basins in Tianshan Mountain in consideration of glacier area changes. The results suggested that：（1）FLEXG-Δh model has high simulation accuracy for the historical runoff process because the average Kling-Gupta coefficient（IKGE）in calibration is 0. 75 and IKGE in validation is 0. 60. （2）Precipitation increases along with elevation while runoff and evaporation increase first but then decreased，with the maximum values at 4 000 m and 2 000 m respectively. The height zone with the greatest runoff is mainly affected by the glacier cover，while it is the distribution of forest for the greatest evaporation. （3）By 2100，the glaciers at low altitudes will melt significantly，while there will be a little melting above 4 500 m. Under SSP1-RCP2. 6 and SSP5-RCP8. 5 scenarios，145 and 222 glaciers will completely melt and the volume of glaciers will decrease 1. 81×104 km3（54% of the existing glaciers）and 2. 44×104 km3（73% of the existing glaciers），respectively. In the SSP5-RCP8. 5 scenario，the rise of temperature will increase the evap⁃ oration but lead to the fact that the runoff depth will decrease 0. 16~1. 40 mm·a-1 below 4 000 m and increase 0. 20~0. 67 mm·a-1 above 4 000 m ，causing the height of peak value will go up by about 500 m. Under SSP1-RCP2. 6 scenario，there will be few obvious changes. This study presented the vertical zonal law of hydrology and vegetation，and predicted the impact of global changes on the Tianshan Mountains，which provided theoreti⁃ cal support for water utilization and sustainable development.
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| 7. |
- Sigeman, Hanna, et al.
(author)
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A novel neo-sex chromosome in Sylvietta brachyura (Macrosphenidae) adds to the extraordinary avian sex chromosome diversity among Sylvioidea songbirds
- 2022
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In: Journal of evolutionary biology. - : Wiley. - 1010-061X .- 1420-9101. ; 35:12, s. 1797-1805
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Journal article (peer-reviewed)abstract
- We report the discovery of a novel neo-sex chromosome in an African warbler, Sylvietta brachyura (northern crombec; Macrosphenidae). This species is part of the Sylvioidea superfamily, where four separate autosome–sex chromosome translocation events have previously been discovered via comparative genomics of 11 of the 22 families in this clade. Our discovery here resulted from analyses of genomic data of single species-representatives from three additional Sylvioidea families (Macrosphenidae, Pycnonotidae and Leiothrichidae). In all three species, we confirmed the translocation of a part of chromosome 4A to the sex chromosomes, which originated basally in Sylvioidea. In S. brachyura, we found that a part of chromosome 8 has been translocated to the sex chromosomes, forming a unique neo-sex chromosome in this lineage. Furthermore, the non-recombining part of 4A in S. brachyura is smaller than in other Sylvioidea species, which suggests that recombination continued along this region after the fusion event in the Sylvioidea ancestor. These findings reveal additional sex chromosome diversity among the Sylvioidea, where five separate translocation events are now confirmed.
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| 8. |
- Sigeman, Hanna, et al.
(author)
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Avian Neo-Sex Chromosomes Reveal Dynamics of Recombination Suppression and W Degeneration
- 2021
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In: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 38:12, s. 5275-5291
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Journal article (peer-reviewed)abstract
- How the avian sex chromosomes first evolved from autosomes remains elusive as 100 million years (My) of divergence and degeneration obscure their evolutionary history. The Sylvioidea group of songbirds is interesting for understanding avian sex chromosome evolution because a chromosome fusion event similar to 24 Ma formed "neo-sex chromosomes" consisting of an added (new) and an ancestral (old) part. Here, we report the complete female genome (ZW) of one Sylvioidea species, the great reed warbler (Acrocephalus arundinaceus). Our long-read assembly shows that the added region has been translocated to both Z and W, and whereas the added-Z has retained its gene order the added-W part has been heavily rearranged. Phylogenetic analyses show that recombination between the homologous added-Z and -W regions continued after the fusion event, and that recombination suppression across this region took several million years to be completed. Moreover, recombination suppression was initiated across multiple positions over the added-Z, which is not consistent with a simple linear progression starting from the fusion point. As expected following recombination suppression, the added-W show signs of degeneration including repeat accumulation and gene loss. Finally, we present evidence for nonrandom maintenance of slowly evolving and dosage-sensitive genes on both ancestral- and added-W, a process causing correlated evolution among orthologous genes across broad taxonomic groups, regardless of sex linkage.
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| 9. |
- Sigeman, Hanna, et al.
(author)
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Insights into avian incomplete dosage compensation : Sex-biased gene expression coevolves with sex chromosome degeneration in the common whitethroat
- 2018
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In: Genes. - : MDPI AG. - 2073-4425. ; 9:8
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Journal article (peer-reviewed)abstract
- Non-recombining sex chromosomes (Y and W) accumulate deleterious mutations and degenerate. This poses a problem for the heterogametic sex (XY males; ZW females) because a single functional gene copy often implies less gene expression and a potential imbalance of crucial expression networks. Mammals counteract this by dosage compensation, resulting in equal sex chromosome expression in males and females, whereas birds show incomplete dosage compensation with significantly lower expression in females (ZW). Here, we study the evolution of Z and W sequence divergence and sex-specific gene expression in the common whitethroat (Sylvia communis), a species within the Sylvioidea clade where a neo-sex chromosome has been formed by a fusion between an autosome and the ancestral sex chromosome. In line with data from other birds, females had lower expression than males at the majority of sex-linked genes. Results from the neo-sex chromosome region showed thatWgametologs have diverged functionally to a higher extent than their Z counterparts, and that the female-to-male expression ratio correlated negatively with the degree of functional divergence of these gametologs. We find it most likely that sex-linked genes are being suppressed in females as a response to W chromosome degradation, rather than that these genes experience relaxed selection, and thus diverge more, by having low female expression. Overall, our data of this unique avian neo-sex chromosome system suggest that incomplete dosage compensation evolves, at least partly, through gradual accumulation of deleterious mutations at the W chromosome and declining female gene expression.
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| 10. |
- Zhang, Hongkai, et al.
(author)
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Assessment of phylogenetic approaches to study the timing of recombination cessation on sex chromosomes
- 2022
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In: Journal of evolutionary biology. - : Wiley. - 1010-061X .- 1420-9101. ; 35:12, s. 1721-1733
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Journal article (peer-reviewed)abstract
- The evolution of sex chromosomes is hypothesized to be punctuated by consecutive recombination cessation events, forming “evolutionary strata” that ceased to recombine at different time points. The demarcation of evolutionary strata is often assessed by estimates of the timing of recombination cessation (tRC) along the sex chromosomes, commonly inferred from the level of synonymous divergence or with species phylogenies at gametologous (X-Y or Z-W) sequence data. However, drift and selection affect sequences unpredictably and introduce uncertainty when inferring tRC. Here, we assess two alternative phylogenetic approaches to estimate tRC; (i) the expected likelihood weight (ELW) approach that finds the most likely topology among a set of hypothetical topologies and (ii) the BEAST approach that estimates tRC with specified calibration priors on a reference species topology. By using Z and W gametologs of an old and a young evolutionary stratum on the neo-sex chromosome of Sylvioidea songbirds, we show that the ELW and BEAST approaches yield similar tRC estimates, and that both outperform two frequently applied approaches utilizing synonymous substitution rates (dS) and maximum likelihood (ML) trees, respectively. Moreover, we demonstrate that both ELW and BEAST provide more precise tRC estimates when sequences of multiple species are included in the analyses.
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