Variation in biomass elemental composition of grassland plants may have important implications for ecosystem functioning in response to global change. However, relevant studies have mostly focused on ...variation of nitrogen (N) and phosphorus (P) concentrations in plant leaves, while few studies have evaluated other elements and plant organs of grassland species. Here, we examined the effects of N addition on multi-element concentrations, and analyzed their patterns across different organs (leaf, stem, root and seed) of five plant species in a steppe community of the Inner Mongolian grassland. Our results showed that seeds exhibited the most stable elemental composition with N addition, and that manganese (Mn) and iron (Fe) concentrations were substantially more variable than macro-elements in response to N addition. In particular, we identified a set of significant negative relationships between elemental concentrations and their corresponding CVs (coefficients of variation) for all plant organs as a whole and for each individual organ. We further found that changes in soil pH and the availability of soil nutrients contributed mostly to variation in the biomass elemental composition of major plants in this community. These findings are important for accurately assessing the effects of N deposition on the biochemical cycling of nutrient elements in grassland ecosystems, and provide critical clues for developing effective approaches to adaptively managing grassland resources as well as mitigating the impact of global change on the dryland ecosystems in the Mongolia Plateau.
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•Seeds exhibited the most stable elemental composition with nitrogen addition.•Biomass Mn and Fe were most responsive to nitrogen addition.•Variation of soil pH and soil nutrient availability contributed mostly to changes in biomass elemental composition.
Phosphatases are a class of enzymes catalyzing the cleavage of monophosphate ester bonds from the phosphorylated substrates. They have important applications in construction of in vitro ...multi‐enzymatic system for monosaccharides. However, the enzymes generally show substrate ambiguity, which has become a bottleneck for efficient biosynthesis of target products with high purity. In this study, semirational design was performed on phosphatase from Thermosipho atlanticus (Ta‐PST). The hotspot amino acid residues forming a “cap domain” were identified and selected for saturation mutagenesis. The mutant F179T and F179M showed improved substrate preference toward fructose‐6‐phosphate and mannose‐6‐phosphate, respectively. Coupling with other enzymes involved in the multi‐enzymatic system under optimized conditions, the application of F179T led to fructose yield of 80% from 10 g/L maltodextrin and the ratio between the target product and by‐product glucose was increased from 2:1 to 19:1. On the other hand, the application of F179M led to mannose yield of 59% with ratio of mannose to the by‐products glucose and fructose increased from 1:1:1 to 14:2:1. Moreover, the molecular understanding of the beneficial substitution was gained by structural analysis and molecular dynamic simulations, giving important guidance to regulate the enzyme's substrate preference.
Collagen is one of the most useful biomaterials and widely applied in functional food and cosmetics. However, some consumers have paid close attention to the safety of mammalian collagens because of ...the outbreaks of bovine spongiform encephalopathy (BSE), foot-and-mouth disease (FMD), and other prion diseases. Therefore, there is a strong demand for developing alternative sources of collagen, with one promising source being from the process by-products of commercial fisheries. In this report, acid-soluble collagen (ASC-SB) and pepsin-soluble collagen (PSC-SB) from swim bladders of miiuy croaker (
) were isolated with yields of 1.33 ± 0.11% and 8.37 ± 0.24% of dry swim bladder weight. Glycine was the major amino acid present, with a content of 320.5 (ASC-SB) and 333.6 residues/1000 residues (PSC-SB). ASC-SB and PSC-SB had much lower denaturation temperatures compared to mammalian collagen, a consequence of low imino acid contents (196.7 and 199.5 residues/1000 residues for ASC-SB and PSC-SB, respectively). The data of amino acid composition, SDS-PAGE pattern, UV and FTIR spectra confirmed that ASC-SB and PSC-SB were mainly composed of type I collagen. FTIR spectra data indicated there were more hydrogen bonding and intermolecular crosslinks in ASC-SB. These collagens showed high solubility in the acidic pH ranges and low NaCl concentrations (less than 2%). The Zeta potential values of ASC-SB and PSC-SB were 6.74 and 6.85, respectively. ASC-SB and PSC-SB presented irregular, dense, sheet-like films linked by random-coiled filaments under scanning electron microscopy. In addition, ASC-SB and PSC-SB could scavenge DPPH radical, hydroxyl radical, superoxide anion radical, and ABTS radical in a dose-dependent manner. Overall, the results indicate that collagens from the swim bladders of miiuy croaker are a viable substitute for mammalian collagen, with potential functional food and cosmeceutical applications.
In this work, oxygen‐deficient anatase TiO2 nanosheets (A‐TiO2−xNSs) are proposed as a substrate to improve the electrochemical properties of sulfur electrodes for lithium‐sulfur (Li‐S) batteries. ...The A‐TiO2−xNSs are prepared by partly reducing pristine TiO2 nanosheets (A‐TiO2NSs) in NaBH4 solution. With some oxygen vacancies on the surface of the TiO2 nanosheets, A‐TiO2−xNSs not only promote electronic transfer, but also act as more effective polysulfide reservoirs to minimize the dissolution of lithium polysulfides (LiPSs) than the A‐TiO2NSs control. Hence, upon utilization as modifiers for cathodes of Li‐S batteries, the A‐TiO2−xNSs‐modified sulfur (A‐TiO2−xNSs‐S) cathode exhibits a higher reversible specific capacity and greater cycling performance and rate capability than the A‐TiO2NSs‐modified one (A‐TiO2NSs‐S). For example, A‐TiO2−xNSs‐S delivers an initial specific capacity of 1277.1 mAh g−1 at 0.1 C and maintains a stable Coulombic efficiency of approximately 99.2 % after the first five cycles; these values are higher than those of 997.3 mAh g−1 and around 96.7 %, respectively, for A‐TiO2NSs‐S. The enhanced electrochemical properties of the A‐TiO2−xNSs‐S cathode can be ascribed mainly to the more effective adsorption of dissolvable and diffused LiPSs by the oxygen vacancies. Therefore, utilization of the structure of oxygen vacancies in Li‐S batteries demonstrates great prospects for practical application.
Oxygen‐deficient cathode: A sulfur cathode modified with oxygen‐deficient anatase TiO2 nanosheets (A‐TiO2−xNSs‐S cathode) performs better in lithium‐sulfur batteries than the A‐TiO2NSs‐S cathode (see figure). Oxygen vacancies on the surface of the A‐TiO2−xNSs provide robustly interactional active sites for lithium polysulfides, which efficiently relieve the shuttle effect, so the A‐TiO2−xNSs‐S cathode shows superior electrochemical properties to the A‐TiO2NSs‐S cathode.
Natural proteins exhibit rich structural diversity based on the folds of an invariably linear chain. Macromolecular catenanes that cooperatively fold into a single domain do not belong to the current ...protein universe, and their design and synthesis open new territories in chemistry. Here, we report the design, synthesis, and properties of a single-domain green fluorescent protein catenane via rewiring the connectivity of GFP's secondary motifs. The synthesis could be achieved in two steps via a pseudorotaxane intermediate or directly via expression in cellulo. Various proteins-of-interest may be inserted at the loop regions to give fusion protein catenanes where the two subunits exhibit enhanced thermal resilience, thermal stability, and mechanical stability due to strong conformational coupling. The strategy can be applied to other proteins with similar fold, giving rise to a family of single-domain fluorescent proteins. The results imply that there may be multiple protein topological variants with desirable functional traits beyond their corresponding linear protein counterparts, which are now made accessible and fully open for exploration.
Many studies have shown that microRNAs (miRNAs) play vital roles during the spermatogenesis. However, little is known about the altered miRNA profiles of testicular tissues in nonobstructive ...azoospermia (NOA). Using microarray technology, the miRNA expression profiles of testicular biopsies from patients with NOA and of normal testicular tissues were determined. Bioinformatics analyses were conducted to predict the enriched biological processes and functions of identified miRNAs. The microarray data were validated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the results of which were then validated with a larger sample size. Correlations between the miRNA expression levels and clinical characteristics were analyzed. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic ability of miRNAs for azoospermia. Hierarchical clustering showed that 129 miRNAs were significantly differentially expressed between the NOA and control groups. Bioinformatics analysis indicated that the differentially expressed miRNAs were involved in spermatogenesis, cell cycle, and mitotic prometaphase. In the subsequent qRT-PCR assays, the selected miRNA expression levels were consistent with the microarray results, and similar validated results were obtained with a larger sample size. Some clinical characteristics were significantly associated with the expression of certain miRNAs. In particular, we identified a combination of two miRNAs (miR-10b-3p and miR-34b-5p) that could serve as a predictive biomarker of azoospermia. This study provides altered miRNA profiles of testicular biopsies from NOA patients and examines the roles of miRNAs in spermatogenesis. These profiles may be useful for predicting and diagnosing the presence of testicular sperm in individuals with azoospermia.
Background & Aims
The multiplicity of hepatocellular carcinoma (HCC) recurrence patterns is the most important determinant of patients' postsurgical survival. A systematic HCC recurrence ...classification is needed to help prevent and treat postoperative HCC recurrence in the era of precision medicine.
Methods
A total of 1319 patients with recurrent HCC from four hospitals were enrolled and divided into a development cohort (n = 916), internal validation cohort (n = 225) and external validation cohort (n = 178). A comprehensive study of patients' clinicopathological factors and biological features was conducted.
Results
Four subtypes of recurrence were identified, which integrated recurrence features, survival, effects on systemic and liver function and potential therapeutics after recurrence: type I (solitary‐intrahepatic oligorecurrence); type II (multi‐intrahepatic oligorecurrence); type III (progression recurrence) and type IV (hyper‐progression recurrence). Type III~IV recurrence indicated exceptionally poor prognosis. Subsequently, two nomogram models were established for type III~IV recurrence prediction, and both demonstrated excellent predictive performance and applicability of pre and postoperative strategy formulation. Multiple biological analyses revealed that HCC cases with type III~IV recurrence were characterized by enrichment in p53 mutations, CCND1 amplification, high proliferation/metastasis potential, inactive metabolism and immune exhaustion features. Over‐expression of high mobility group protein 2 (HMGA2) enhanced the highly malignant behaviour of HCC through multiple molecular pathways, making it a potential prognostic predictor and therapeutic target.
Conclusions
This ‘recurrent HCC classification’ has important potential value in identifying patients with surgical benefit, predicting postsurgical survival and guiding treatment strategies. Multidimensional biological insights also increased knowledge of factors associated with HCC recurrence.
To investigate health-related quality of life (HRQOL) in children with postoperative delirium (POD) after surgical repair of ventricular septal defects (VSDs).
A total of 109 patients were enrolled ...and assigned to the POD group (n = 47) and the non-POD group (n = 62). HRQOL was assessed by the PedsQLTM 3.0 Cardiac Module at discharge, and at the three- and six-month postoperative follow.
Significant differences were detected in age, operation time, CPB time, mechanical ventilation duration, and length of ICU stay between the two groups, whereas sex and the VSD size did not significantly differ between groups. In terms of "cardiac heart problems and treatment" and "treatment-II", the HRQOL scores of the non-POD group were significantly better than those of the POD group. In terms of "perceived physical appearance" and "treatment anxiety", the POD group had significantly higher scores than the non-POD group at discharge and at the three-month postoperative follow-up. In terms of "cognitive problems" and "communication", the occurrence of POD still affected HRQOL at three months postoperatively, but the effect was significantly reduced at six months postoperatively. In terms of "total scores", both groups scored increasingly higher over time. The non-POD group had higher scores at discharge and three months postoperatively than the POD group, but no significant difference persisted at six months postoperatively.
During the follow-up period, the HRQOL of the children with POD after surgical repair of VSD was inferior to that of the children without POD at discharge and three months postoperatively. However, the HRQOL did not differ between the two groups at six months postoperatively.
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