Long-term fencing can't benefit plant and microbial network stability of alpine meadow and alpine steppe in Three-River-Source National Park.

A great number of fencing facilities has been established in Three-River-Source National Park. However, with the transformation of wild animals into the main consumers of grassland ecosystem and the increasing years of fence (>15 years), whether the fence still has a positive effect on grassland ecosystem has become controversial. Therefore, taking the alpine steppe and alpine meadow in Three-River-Source National Park as the case study, this study focused on the effects of long-term enclosure on different ecological components by investigating plant communities, soil physical and chemical characteristics and soil microbial characteristics (16S, ITS). Furthermore, we evaluated the ecological benefits of long-term fencing based on the stability of plant communities and microbial networks. We found that fencing did not significantly promote the stability of plant community in different grassland types. The analysis of bacteria-fungal symbiotic network indicated that fencing significantly reduced the stability of soil microbial network in alpine meadows. The results of structural equation showed that the microbial community was indirectly affected by the changes of soil moisture content (SMC) and soil total nutrient content in the alpine steppe, and the stability of microbial network was significantly correlated with the diversity of fungal community. In alpine meadows, fencing indirectly affected soil microbial community by changing SMC and pH. High SMC was not conducive to microbial network stability, while high plant community stability was beneficial to microbial network stability. Network stability was remarkably related to bacterial community composition and diversity, as well as fungal community diversity. Therefore, in Three-River-Source National Park, the positive effects of long-term fencing on various components in different grassland types are weak, especially the negative effects on the stability of soil microbial community in alpine meadows may also weaken the stability of the ecosystem, which is not conducive to the ecological protection of grassland ecosystem.

Soil moisture and pH differentially drive arbuscular mycorrhizal fungal composition in the riparian zone along an alpine river of Nam Co watershed.

The riparian zone is an important ecological corridor connecting the upstream and downstream rivers. Its highly complex biological and physical environments significantly affect the biogeographical pattern of species and various ecosystem functions. However, in alpine riparian ecosystems, the distribution patterns and drivers of arbuscular mycorrhizal (AM) fungi, a group of functionally important root-associated microorganisms, remain poorly understood. In this study, we investigated the AM fungal diversity and community composition in near-bank (wetland) and far-bank (alpine meadows) soils along the Niaqu River in the Nam Co watershed, and assessed the relative importance of abiotic and biotic filtering in shaping these distributions. Overall, 184 OTUs were identified in the riparian ecosystem, predominantly belonging to the genus Glomus, especially in the downstream soils, and Claroideoglomus in near-bank soils. AM fungal colonization, spore density, and α diversity showed an overall increasing trend along the river, while the extraradical hyphae declined dramatically from the middle of the river. AM fungal communities significantly varied between the wetland and alpine meadows in the riparian zone, mainly driven by the geographic distance, soil water content, soil pH, and plant communities. Specifically, soil pH was the principal predictor of AM fungal community in near-bank wetland soils, while soil water content had a most substantial direct effect in alpine meadows. These findings indicate that abiotic factors are the most important divers in shaping AM fungal communities at the watershed scale, which could be helpful in alpine riparian biodiversity conservation and management.

Maltose-functionalized HILIC stationary phase silica gel based on self-assembled oligopeptides and its application for the separation of polar compounds.

In this study, carbonyldiimidazole was used to bond maltose-modified oligopeptides (Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys) to the surface of silica spheres for hydrophilic interaction liquid chromatography (HILIC). Attenuated total reflectance-Fourier transform infrared spectroscopy, elemental analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, BET technique, and water contact angle measurement results confirmed the successful immobilization of the obtained material. Compared with the conventional method for preparing carbohydrate stationary phases, this method involves simpler steps and less time-consuming processes. The experimental results proved that the retention mechanism of the maltose-based HILIC column matched the typical HILIC retention mechanism. The column showed high separation efficiency and stability toward the separation of polar compounds such as amino acids, bases, nucleosides, water-soluble vitamins, and salicylic acid and its analogs. The column achieved high selectivity toward oligosaccharide separation. In addition, this efficient analysis demonstrates the applicability of the as-prepared material in the field of food inspection.

C18-functionalized magnetic nanocomposites fabricated by one-step aqueous coating of tailored oligopeptides for enrichment of low-abundance peptides.

Screening and monitoring endogenous peptides from complicated biosamples is still a major challenge in mass spectrometry-based proteomics research, mainly due to their low concentration and the interference of high-abundance proteins and other contaminants in biological samples. Herein, a facile and novel approach was described for rapid fabrication of C18-functionalized magnetic nanocomposites (C18-MNCs) based on one-step aqueous coating of C18-Val-Lys-Val-Lys-Val-Lys (C18-VK-VI) for the highly selective enrichment of low-abundance endogenous peptides from biological samples. C18-VK-VI can readily self-assemble into complete monolayers mainly composed of ß-sheets with C18 hydrophobic chains erecting on the surface of GO@Fe3O4 MNCs under the physiological conditions. The resulting C18VK-VI-GO@Fe3O4 MNCs exhibited good performance for peptides enrichment from digests of standard protein (myoglobin, MYO) and human serum, such as high sensitivity (0.05 fmol µL-1) and selectivity (mass ratio of MYO digests and MYO = 1:500), rapid separation, and good reproducibility. Such a simple mild and rapid one-step aqueous coating method on the basis of oligopeptides self-assembly showed great potential in surface functionalization of various nanoadsorbents for proteome/peptidome researches.

Specific enrichment of phosphopeptides by using magnetic nanocomposites of type Fe3O4@graphene oxide and Fe3O4@C coated with self-assembled oligopeptides.

Iron(III-immobilized magnetic nano-composites (MNCs) were first fabricated using one-step aqueous self-assembly of oligopeptides (Glu-Pro-Ala-Lys-Ala-Lys-Ala-Lys; EPAK-VI) for the highly selective capture of phosphopeptides from complex biological samples. Under physiological conditions, EPAK-VI can readily self-organize into a robust and complete coating layer mainly composed of ß-sheets and ß-turns on the surface of Fe3O4@GO and Fe3O4@C MNCs. Tailored by the cyclic structure of proline, the Glu-Pro motifs of EPAK-VI are vertically erected on the surface and thus serve as an effective linker to chelate Fe3+ through carboxyl (COO-) group in the glutamic acid (E) residues. The ionic hydrogen bonds between the ε-amino groups and the surface negative charges coupled with intermolecular hydrogen bonds render the EPAK-VI coating on the MNCs insusceptible to repeated extreme washing conditions. The Fe3+-EPAK-VI coated MNCs exhibit high enrichment efficiency for ß-casein tryptic digest (0.05 fmol µL-1), excellent selectivity from mixed digests (ß-casein/bovine serum albumin, mass ratio 1:500), and high recovery rate (over 80%). Graphical abstractSchematic representation of the fabrication of Fe3+-immobilized MNCs for phosphopeptide enrichment.

One-step fabrication of bifunctional self-assembled oligopeptides anchored magnetic carbon nanoparticles and their application in copper (II) ions removal from aqueous solutions.

Copper ion (Cu (II)) pollution has attracted much attention due to its remarkable toxic domino effect at excess amount. Efficient Cu (II) ions removal is thus a prerequisite for wastewater recycling. Herein, we present a facile and environmentally benign strategy to fabricate thiol (SH)-functionalized Fe3O4@C nanoparticles (denoted as Fe3O4@C-SH NPs) based on one-step self-assembling of a bifunctional oligopeptide with a sequence of Cys-Lys-Cys-Lys-Cys-Lys (CK-VI) for highly efficient removal of copper ions (Cu (II)) in aqueous solutions. Under the physiological conditions, CK-VI readily self-organized into a robust and tailor-made functional monolayer predominately composed of well-packed ß-sheets on the surface of Fe3O4@C NPs with their thiol groups standing on the outermost layer. The resulting Fe3O4@C-SH NPs containing abundant thiol active sites exhibited excellent adsorption capacity (up to 28.8 mg g-1) and selectivity for Cu (II) ions over coexisting ions. Compared with other covalent grafting methods with multistep processes and in harsh conditions, the proposed oligopeptides assembly-based coating method makes it possible to rapidly fabricate the Fe3O4@C-SH NPs in a simple mild one-step aqueous process with low cost. The current study provides facile and environmentally friendly approaches to rapidly tailor multifunctional surfaces of NPs for various toxic metal ions removal from wastewater.

One-step maltose-functionalization of magnetic nanoparticles based on self-assembled oligopeptides for selective enrichment of glycopeptides.

Magnetic nanoparticles (MNPs) have been widely explored in enrichment of low-abundance glycoproteins/glycopeptides prior to mass spectrometry analysis in glycoproteomics. Currently, most functional groups for recognizing glycoproteins/glycopeptides are usually immobilized on the nanomaterial surface based on covalent modification, which suffers from multistep treatment, surface-dependence, and harsh conditions. In this work, we first report a facile and rapid method for surface functionalization and subsequent glycopeptides enrichment via one-step assembly of maltose-modified oligopeptides with a sequence of Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys (AEK8-maltose). In physiological conditions, AEK8-maltose readily self-organized into a complete coating layer dominated by ß-sheets on the surface of SiO2@Fe3O4 and C@Fe3O4 MNPs, which remain intact to repeat washing with acidic organic and aqueous solutions extensively used in the sample enrichment treatments. Thus, the resulting AEK8-maltose functionalized MNPs show excellent performance in enrichment of glycopeptides in standard glycoprotein digests (24 glycopeptides from horseradish peroxidase (HRP), 31 glycopeptides from immunoglobulin (IgG)) and human serum digests (282 glycopeptides), including rapid enrichment speed (5 min), high detection sensitivity (0.001 ng/µL HRP), high selectivity (mass ratios of HRP and bovine serum albumin (BSA) digests up to 1:150), good enrichment recovery (over 86.3%), remarkable stability (repeatable for more than 8 times), and excellent renewability, which are better than or comparable with the literature results reported to date. The current work based on self-assembling oligopeptides provides a mild, economic and nontoxic procedure for one-step surface functionalization of various nanomaterials.