Sex-specific competition differently regulates the response of the rhizosphere fungal community of Hippophae rhamnoides-A dioecious plant, under Mn stress.

In this study, we investigated the soil physicochemical parameters and responses of rhizospheric fungal communities of Hippophae rhamnoides to Mn stress under different sexual competition patterns. The results showed that competition significantly affects soil physicochemical properties, enzyme activity, and rhizosphere-associated fungal community structures. Under Mn stress, soils with intersexual competition had higher levels of N supply than those with the intrasexual competition. Moreover, fungal communities under intersexual interaction were more positive to Mn stress than intrasexual interaction. Under intrasexual competition, female plants had higher total phosphorus content, neutral phosphatase activity, and relative abundance of symbiotic fungi in soils to obtain phosphorus nutrients to alleviate Mn stress. In contrast, male plants had relatively stable fungal communities in soils. In the intersexual competition, rhizosphere fungal diversity and relative abundance of saprophytic fungi in male plants were significantly higher than in female plants under Mn stress. In addition, female plants showed greater plasticity in the response of rhizosphere microorganisms to their neighbors of different sexes. The microbial composition in soils of female plants varied more than male plants between intrasexual and intersexual competition. These results indicated that sex-specific competition and neighbor effects regulate the microbial community structure and function of dioecious plants under heavy metal stress, which might affect nutrient cycling and phytoremediation potential in heavy metal-contaminated soils.

Switching from membrane disrupting to membrane crossing, an effective strategy in designing antibacterial polypeptide.

Drug-resistant bacterial infections have caused serious threats to human health and call for effective antibacterial agents that have low propensity to induce antimicrobial resistance. Host defense peptide-mimicking peptides are actively explored, among which poly-ß-l-lysine displays potent antibacterial activity but high cytotoxicity due to the helical structure and strong membrane disruption effect. Here, we report an effective strategy to optimize antimicrobial peptides by switching membrane disrupting to membrane penetrating and intracellular targeting by breaking the helical structure using racemic residues. Introducing ß-homo-glycine into poly-ß-lysine effectively reduces the toxicity of resulting poly-ß-peptides and affords the optimal poly-ß-peptide, ßLys50HG50, which shows potent antibacterial activity against clinically isolated methicillin-resistant Staphylococcus aureus (MRSA) and MRSA persister cells, excellent biosafety, no antimicrobial resistance, and strong therapeutic potential in both local and systemic MRSA infections. The optimal poly-ß-peptide demonstrates strong therapeutic potential and implies the success of our approach as a generalizable strategy in designing promising antibacterial polypeptides.

Statistic Copolymers Working as Growth Factor-Binding Mimics of Fibronectin.

Growth factors (GFs) play important roles in biological system and are widely used in tissue regeneration. However, their application is greatly hindered by short in vivo lifetime of GFs. GFs are bound to fibronectin dynamically in the extracellular matrix, which inspired the authors to mimic the GF binding domain of fibronectin and design GF-binding amphiphilic copolymers bearing positive charges. The optimal amino acid polymer can bind to a variety of representative GFs, such as bone morphogenetic protein-2 (BMP-2) and TGF-ß1 from the transforming growth factor-ß superfamily, PDGF-AA and PDGF-BB from the platelet-derived growth factor family, FGF-10 and FGF-21 from the fibroblast growth factor family, epidermal growth factor from the EGF family and hepatocyte growth factor from the plasminogen-related growth factor family, with binding affinities up to the nanomolar level. 3D scaffolds immobilized with the optimal copolymer enable sustained release of loaded BMP-2 without burst release and significantly enhances the in vivo function of BMP-2 for bone formation. This strategy opens new avenues in designing GF-binding copolymers as synthetic mimics of fibronectin for diverse applications.

Amphipathic poly-ß-peptides for intracellular protein delivery.

A series of amphipathic poly-ß-peptides are designed for intracellular protein delivery. The poly-ß-peptides with higher molecular weight and hydrophobic contents exhibit higher protein loading and superior delivery efficiency. The lead material efficiently delivers proteins into cells with reserved bioactivity.

The impact of antifouling layers in fabricating bioactive surfaces.

Bioactive surfaces modified with functional peptides are critical for both fundamental research and practical application of implant materials and tissue repair. However, when bioactive molecules are tethered on biomaterial surfaces, their functions can be compromised due to unwanted fouling (mainly nonspecific protein adsorption and cell adhesion). In recent years, researchers have continuously studied antifouling strategies to obtain low background noise and effectively present the function of bioactive molecules. In this review, we describe several commonly used antifouling strategies and analyzed their advantages and drawbacks. Among these strategies, antifouling molecules are widely used to construct the antifouling layer of various bioactive surfaces. Subsequently, we summarize various structures of antifouling molecules and their surface grafting methods and characteristics. Application of these functionalized surfaces in microarray, biosensors, and implants are also introduced. Finally, we discuss the primary challenges associated with antifouling layers in fabricating bioactive surfaces and provide prospects for the future development of this field. STATEMENT OF SIGNIFICANCE: The nonspecific protein adsorption and cell adhesion will cause unwanted background "noise" on the surface of biological materials and detecting devices and compromise the performance of functional molecules and, therefore, impair the performance of materials and the sensitivity of devices. In addition, the selection of antifouling surfaces with proper chain length and high grafting density is also of great importance and requires further studies. Otherwise, the surface-tethered bioactive molecules may not function in their optimal status or even fail to display their functions. Based on these two critical issues, we summarize antifouling molecules with different structures, variable grafting methods, and diverse applications in biomaterials and biomedical devices reported in literature. Overall, we expect to shed some light on choosing the appropriate antifouling molecules in fabricating bioactive surfaces.