The catalytic subunit of type 2A protein phosphatase negatively regulates conidiation and melanin biosynthesis in Setosphaeria turcica.

Northern corn leaf blight caused by Setosphaeria turcica is a major fungal disease responsible for significant reductions in maize yield worldwide. Eukaryotic type 2A protein phosphatase (PP2A) influences growth and virulence in a number of pathogenic fungi, but little is known about its roles in S. turcica. Here, we functionally characterized S. turcica StPP2A-C, which encodes the catalytic C subunit of StPP2A. StPP2A-C deletion slowed colony growth, conidial germination, and appressorium formation but increased conidiation, melanin biosynthesis, glycerol content, and disease lesion size on maize. These effects were associated with expression changes in genes related to calcium signaling, conidiation, laccase activity, and melanin and glycerol biosynthesis, as well as changes in intra- and extracellular laccase activity. A pull-down screen for candidate StPP2A-c interactors revealed an interaction between StPP2A-c and StLac1. Theoretical modeling and yeast two-hybrid experiments confirmed that StPP2A-c interacted specifically with the copper ion binding domain of StLac1 and that Cys267 of StPP2A-c was required for this interaction. StPP2A-C expression thus appears to promote hyphal growth and reduce pathogenicity in S. turcica, at least in part by altering melanin synthesis and laccase activity; these insights may ultimately support the development of novel strategies for biological management of S. turcica.

The Septin Gene StSep4 Contributes to the Pathogenicity of Setosphaeria turcica by Regulating the Morphology, Cell Wall Integrity, and Pathogenic Factor Biosynthesis.

Septins are a conserved group of GTP-binding proteins found in all eukaryotes and are the fourth-most abundant cytoskeletal proteins. Septins of some pathogenic fungi are involved in morphological changes related to infection. Our previous studies have identified four core septins (StSep1-4) in Setosphaeria turcica, the causal agent of northern corn leaf blight, while only StSep4 is significantly upregulated during the invasive process. We therefore used forchlorfenuron (FCF), the specific inhibitor of septin, and ΔStSep4 knockout mutants to further clarify the role of septins in S. turcica pathogenicity. FCF treatment caused a dose-dependent reduction in S. turcica colony growth, delayed the formation of infection structures, and reduced the penetration ability. ΔStSep4 knockout mutants displayed abnormal mycelium morphology, slow mycelial growth, conidiation deficiency, delayed appressorium development, and weakened pathogenicity. StSep4 deletion also broke cell wall integrity, altered chitin distribution, decreased the melanin content, and disrupted normal nuclear localization. A transcriptomic comparison revealed that genes differentially expressed between ΔStSep4 and WT were enriched in terms of ribosomes, protein translation, membrane components, and transmembrane transport activities. Our results demonstrate that StSep4 is required for morphology and pathogenicity in S. turcica, making it a promising target for the development of novel fungicides.

The Influence of Entrepreneurial Cognition on Business Model Innovation: A Hybrid Method Based on Multiple Regressions and Machine Learning.

How to achieve business model innovation (BMI) has always been a focus topic in the field of entrepreneurship. Based on cognitive theory, this study takes new ventures as the research object to build a theoretical model to explore the impact of entrepreneurial cognition on BMI choice, its intermediary mechanism, and boundary conditions. We test our framework with a sample of 242 questionnaires; the empirical research results show that entrepreneurial configuration cognition, willing cognition, and ability cognition indirectly affect the BMI of new ventures. Strategic sensitivity (SSE) mediated the relationship between entrepreneurial cognition and BMI; knowledge diversity positively moderates the relationship between SSE and BMI. Machine learning algorithm research has found three prediction models for BMI of new ventures. By constructing a theoretical analysis framework of BMI from the perspective of cognition, the results deepen the relevant research on BMI of new ventures, clarify the source of unique characteristics and capabilities of entrepreneurs, provide a new research perspective for analyzing the impact mechanism of entrepreneurial cognition on BMI, enrich the research results in the field of "situation-cognition behavior," and further clarify the important role of knowledge in the development of new ventures.

A single von Willebrand factor C-domain protein acts as an extracellular pattern-recognition receptor in the river prawn Macrobrachium nipponense.

The single von Willebrand factor C-domain proteins (SVWCs) are mainly found in arthropods. Their expression may be regulated by several environmental stresses, including nutritional status and bacterial and viral infections. However, the underlying regulatory mechanism is unclear. In the present study, we identified a member of the SVWC family from the river prawn Macrobrachium nipponense as a soluble and bacteria-inducible pattern-recognition receptor (designated MnSVWC). In vitro, recombinant MnSVWC exhibited pronounced binding and Ca2+-dependent agglutinating abilities against diverse microbes, including Gram-negative bacteria (i.e. Escherichia coli and Aeromonas victoria), Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), and yeast (Pichia pastoris). ELISA assays revealed that recombinant MnSVWC recognizes a broad range of various pathogen-associated molecular patterns (PAMPs) and has high affinity to lipopolysaccharide and lysine-type and diaminopimelic acid-type peptidylglycan and d-galactose and low affinity to d-mannan and ß-1,3-glucan. Mutant MnSVWCP57A with an impaired Glu-Pro-Asn (EPN) motif displayed reduced affinity to all these PAMPs to varying extent. Moreover, MnSVWC bound to the surface of hemocytes and promoted their phagocytic activity and clearance of invasive bacteria. RNAi-mediated MnSVWC knockdown in prawn reduced the ability to clear invading bacteria, but did not block the activities of the Toll pathway or the arthropod immune deficiency (IMD) pathway, or the expression of antimicrobial peptide genes. These results indicate that MnSVWC functions as an extracellular pattern-recognition receptor in M. nipponense that mediates cellular immune responses by recognizing PAMPs, agglutinating invasive microbes, and promoting phagocytosis in hemocytes.

Lactoferrin-containing immunocomplex mediates antitumor effects by resetting tumor-associated macrophages to M1 phenotype.

BACKGROUND: Tumor-associated macrophages (TAMs) resemble M2-polarized cells with potent immunosuppressive activity and play a pivotal role in tumor growth and progression. Converting TAMs to proinflammatory M1-like phenotype is thus an attractive strategy for antitumor immunotherapy. METHODS: A mouse IgG1 (kappa) monoclonal Ab, M-860, specific to human lactoferrin (LTF) was generated by using the traditional hybridoma cell fusion technology. TAMs were generated by culturing human and mouse CD14+ monocytes in tumor-conditioned media containing a cytokine cocktail containing recombinant interleukin-4 (IL-4), interleukin-10 (IL-10) and macrophage colony stimulating factor (M-CSF). TAMs after treatment with immunocomplex (IC) between human LTF and M860 (LTF-IC) were phenotypically and functionally characterized by flow cytometry (FACS), ELISA, Q-PCR and killing assays. The antitumor effects of LTF-IC were further analyzed using in vivo experiments employing tumor-bearing human FcγRIIa-transgenic mouse models. RESULTS: Through coligation of membrane-bound CD14 and FcγRIIa, LTF-IC rendered TAMs not only M2 to M1 conversion, evidenced by increased tumor necrosis factor α production, down-regulated M2-specific markers (CD206, arginase-1 and vascular endothelial growth factor) and upregulated M1-specific markers (CD86 and HLA-DR) expression, but also potent tumoricidal activity in vitro. LTF-IC administration conferred antitumor protective efficacy and prolonged animal survival in FcγRIIa-transgenic mice, accompanied by accumulation of M1-like macrophages as well as significantly reduced infiltration of immunosuppressive myeloid-derived suppressor cells and regulatory T cells in solid tumor tissues. CONCLUSIONS: LTF-IC is a promising cancer therapeutic agent capable of converting TAMs into tumoricidal M1-like cells.

MdRDH1, a HSP67B2-like rhodanese homologue plays a positive role in maintaining redox balance in Musca domestica.

Rhodanese homology domains (RHODs) are the structural modules of ubiquitous tertiary that occur in three major evolutionary phyla. Despite the versatile and important physiological functions of RHODs containing proteins, little is known about their invertebrate counterparts. A novel HSP67B2-like single-domain rhodanese homologue, MdRDH1 from Musca domestica, whose expression can be induced by bacterial infection or oxidative stress. Silencing MdRDH1 through RNAi causes important accumulations of reactive oxygen species (ROS) and malondialdehyde (MDA), and increases mortality in the larvae treated with bacterial invasion. The E. coli with MdRDH1 and the mutant MdRDH1C135A are transformed, with significant rhodanese activity of the recombinant protein of MdRDH1 in vitro found, without no detection of enzyme activity of the mutant MdRDH1C135A, revealing that catalytic Cys135 in the active-site loop is essential in the sulfurtransferase activity of MdRDH1. When oxidative stress is insulted by phenazine methosulfate (PMS), the MdRDH1 transformed E. coli shows enhanced survival rates compared with those bacteria transformed with MdRDH1C135A. Our research indicates that MdRDH1 confers oxidative stress tolerance, thus rendering evidence for the idea that rhodanese family genes play a critical role in antioxidant defenses. This paper yields novel insights into the potential antioxidative and immune functions of HSP67B2-like rhodanese homologues in invertebrate.