Search

Bile acids, originally known to emulsify dietary lipids, are now established signalling molecules that regulate physiological processes. Signalling targets several proteins that include the ion channels involved in regulating intestinal motility and bile viscosity. Studies show that bile acids regulate the epithelial sodium channel (ENaC) in cultured cell models and heterologous expression systems. ENaC plays both local and systemic roles in regulating extracellular fluids. Here we investigated whether bile acids regulate ENaC expressed in native tissues. We found that taurocholic acid and taurohyodeoxycholic acid regulated ENaC in both the distal nephron and distal colon. We also tested the hypothesis that regulation occurs through direct binding. Using photoaffinity labelling, we found evidence for specific binding to both the β and γ subunits of the channel. In functional experiments, we found that the α subunit was sufficient for regulation. We also found that regulation by at least one bile acid was voltage‐sensitive, suggesting that one binding site may be closely associated with the pore‐forming helices of the channel. Our data provide evidence that bile acids regulate ENaC by binding to multiple sites to influence the open probability of the channel. Key points: Recent studies have shown that bile acids regulate the epithelial sodium channel (ENaC) in vitro. Here we investigated whether bile acids regulate ENaC in native tissues and whether bile acids directly bind the channel.We found that bile acids regulate ENaC expressed in the mouse cortical collecting duct and mouse colon by modulating open probability.Photoaffinity labelling experiments showed specific binding to the β and γ subunits of the channel, while channels comprising only α subunits were sensitive to taurocholic acid in functional experiments using Xenopus oocytes.Taurocholic acid regulation of ENaC was voltage‐dependent, providing evidence for binding to pore‐forming helices.Our data indicate that bile acids are ENaC regulatory effectors that may have a role in the physiology and pathophysiology of several systems. [ABSTRACT FROM AUTHOR]

Apple tree canker infected by Valsa mali var. mali is a serious and widely distributed disease in China. Saccharothrix yanglingensis Hhs.015 is an endophytic actinomycete isolated from cucumber roots, and it has been proven that this strain is a promising biocontrol agent on apple tree canker in previous studies. The aim of this study was to elucidate the active ingredients in its metabolites. Two pentaene macrolides, WH01 and WH02, were isolated from strain Hhs.015, and their structures were elucidated based on the extensive spectroscopic analysis. WH01 and WH02 were identified as fungichromin and 1′-deoxyfungichromin, among which WH02 is a novel compound. These two compounds showed strong in vitro and in vivo antifungal activity against V. mali. By comparison of the structures of hyphae cells treated by pure compound and fermentation broth, it has been proven that pentaene macrolides are the main active ingredients in the metabolites of strain Hhs.015. This is the first report on the antifungal activity of fungichromin and its analogs on V. mali, and the 28-member pentaene macrolides were also firstly isolated from the genus of Saccharothrix. [ABSTRACT FROM AUTHOR]

Soybean cyst nematode (SCN), Heterodera glycines , poses a significant threat to global soybean production. Heilongjiang, the largest soybean-producing province in China, contributes more than 40% to the country's total yield. This province has much longer history of SCN infestation. To assess the current situation in Heilongjiang, we conducted a survey to determine the SCN population density and virulence phenotypes during 2021 to 2022 and compared the data with a previous study in 2015. A total of 377 soil samples from 48 counties representing 11 major soybean-planting regions were collected. The prevalence of SCN increased from 55.4% in 2015 to 59% in the current survey. The population densities ranged from 80 to 26,700 eggs and juveniles per 100 cm 3 of soil. Virulence phenotypes were evaluated for 60 representative SCN populations using the H . glycines (HG) type test, revealing nine different HG types. The most common virulence phenotypes were HG types 7 and 0, accounting for 56.7 and 20% of all SCN populations, respectively. The prevalence of populations with a female index (FI) greater than 10% on PI 548316 increased from 64.5% in 2015 to 71.7%. However, the FI on the commonly used resistance sources PI 548402 (Peking) and PI 437654 remained low at 3.3%. These findings highlight the increasing prevalence and changing virulence phenotypes of SCN in Heilongjiang. They also emphasize the importance of rotating soybean varieties with different resistance sources and urgently identifying new sources of resistance to combat SCN., Competing Interests: The author(s) declare no conflict of interest.

Kiwifruit bacterial canker is a global disease caused by Pseudomonas syringae pv. actinidiae ( Psa ), which poses a major threat to kiwifruit production worldwide. Despite the economic importance of Actinidia chinensis var. chinensis , only a few resistant varieties have been identified to date. In this study, we screened 44 kiwifruit F 1 hybrid lines derived from a cross between two A. chinensis var. chinensis lines and identified two offspring with distinct resistance to Psa : resistant offspring RH12 and susceptible offspring SH14. To identify traits associated with resistance, we performed a comparative transcriptomic analysis of these two lines. We identified several highly differentially expressed genes (DEGs) associated with flavonoid synthesis, pathogen interactions, and hormone signaling pathways, which play essential roles in disease resistance. Additionally, using weighted gene co-expression network analysis, we identified six core transcription factors. Moreover, qRT-PCR results demonstrated the high expression of AcC3H1 and AcREM14 in Psa -induced highly resistant hybrid lines. Ultimately, Overexpression of AcC3H1 and AcREM14 in kiwifruit enhanced disease resistance, and this was associated with upregulation of enzymatic activity and gene expression in the salicylic acid (SA) signaling pathway. Our study elucidates a molecular mechanism underlying disease resistance in kiwifruit and contributes to the advancement of research on kiwifruit breeding., Competing Interests: The authors declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nanjing Agricultural University.)