Antioxidant Defenses Against Air Humidity Stress in Fruit Bodies of Auricularia heimuer (Agaricomycetes).

Air humidity is an important environmental factor restricting the fruit body growth of Auricularia heimuer. Low air humidity causes the fruit body to desiccate and enter dormancy. However, the survival mechanisms to low air humidity for fruit bodies before dormancy remain poorly understood. In the present study, we cultivated A. heimuer in a greenhouse and collected the fruit bodies at different air humidities (90%, 80%, 70%, 60%, and 50%) to determine the contents of malondialdehyde (MDA) and non-enzymatic antioxidants such as ascorbic acid (AsA) and glutathione (GSH); and the activities of enzymatic antioxidants including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and glutathione reductase (GR). Results showed that the MDA contents tended to increase with decreasing relative air humidity. Relative air humidity below 90% caused membrane lipid peroxidation and oxidative stress (based on MDA contents) to the fruit body, which we named air humidity stress. In contrast to the control and with the degree of stress, the GSH contents and activities of SOD, CAT, GR, GPX, and APX tended to ascend, whereas AsA showed a declining trend; the POD activity only rose at 50%. The antioxidants favored the fruit body to alleviate oxidative damage and strengthened its tolerance to air humidity stress. The antioxidant defense system could be an important mechanism for the fruit body of A. heimuer in air humidity stress.

Selective enrichment of virulence factor genes in the plastisphere under antibiotic and heavy metal pressures.

The growing accumulation of plastic waste in the environment has created novel habitats known as the "plastisphere", where microorganisms can thrive. Concerns are rising about the potential for pathogenic microorganisms to proliferate in the plastisphere, posing risks to human health. However, our knowledge regarding the virulence and pathogenic potential of these microorganisms in the plastisphere remains limited. This study quantified the abundance of virulence factor genes (VFGs) in the plastisphere and its surrounding environments (water and soil) to better assess pathogenic risks. Our findings revealed a selective enrichment of VFGs in the plastisphere, which were attributed to the specific microbial community assembled. The presence of arsenic and ciprofloxacin in the plastisphere exerted additional co-selective pressures, intensifying the enrichment of VFGs. Notably, VFGs that encoded multiple functions or enhanced the survival of host microorganisms (e.g., encoding adherence functions) tended to accumulate in the plastisphere. These versatile and environmentally adaptable VFGs are more likely to be favored by bacteria in the environment, warranting increased attention in future investigations due to their potential for widespread dissemination. In terms of virulence and pathogenicity, this research offers new insights into evaluating pathogen-related risks in the plastisphere.

Flooding drives the temporal turnover of antibiotic resistance gene in manure-amended soil-water continuum.

Rice paddy soil is a hotspot of antibiotic resistance genes (ARGs) due to the application of organic fertilizers. However, the temporal dynamics of ARGs in rice paddy soil and its flooded water during the growing season remain underexplored. In this study, a microcosm experiment was conducted to explore the ARG profiles in a long term (130 days) flooded two-phase manure-amended soil-water system. By using high-throughput quantitative PCR array, a total of 23-98 and 34-85 ARGs were detected in the soil and overlying water, respectively. Regression analysis exhibited significant negative correlations between ARG profile similarities and flooding duration, indicating that flooding significantly altered the resistome (P < 0.001). This finding was validated by the increased ARG abundance in the soil and the overlying water, for example, after 130 days flooding, the abundance of ARGs in CK soil was increased from 0.03 to 1.20 copies per 16S rRNA. The PCoA analysis further suggested pig manure application resulted in distinct ARG profiles in the soil-water continuum compared with those of the non-amended control (Adonis, P < 0.05). The Venn diagram showed that all ARGs detected in the pig manure were present in the treated soil. Twelve ARGs (e.g., sul1) were shared among the pig manure, manure-amended soil, and overlying water, indicating that certain manure- or soil-borne ARGs were readily dispersed from the soil to the overlying water. Moreover, the enhanced relationships between the ARGs and mobile genetic elements in pig manure applied soil-water continuum indicate that the application of organic matter could accelerate the emergence and dissemination of ARGs. These findings suggested that flooding represents a crucial pathway for dispersal of ARGs from the soil to the overlying water. Identification of highly mobile ARGs in the soil-water continuum is essential for assessing their potential risk to human health and promoting the development of sustainable agricultural practices to mitigate their spread.

Cataract-causing allele in CRYAA (Y118D) proceeds through endoplasmic reticulum stress in mouse model.

As small heat shock proteins, α-crystallins function as molecular chaperones and inhibit the misfolding and aggregation of ß/γ-crystallins. Genetic mutations of CRYAA are associated with protein aggregation and cataract occurrence. One possible process underlying cataract formation is that endoplasmic reticulum stress (ERS) induces the unfolded protein response (UPR), leading to apoptosis. However, the pathogenic mechanism related to this remains unexplored. Here, we successfully constructed a cataract-causing CRYAA (Y118D) mutant mouse model, in which the lenses of the CRYAA-Y118D mutant mice showed severe posterior rupture, abnormal morphological changes, and aberrant arrangement of crystallin fibers. Histological analysis was consistent with the clinical pathological characteristics. We also explored the pathogenic factors involved in cataract development through transcriptome analysis. In addition, based on key pathway analysis, up-regulated genes in CRYAA-Y118D mutant mice were implicated in the ERS-UPR pathway. This study showed that prolonged activation of the UPR pathway and severe stress response can cause proteotoxic and ERS-induced cell death in CRYAA-Y118D mutant mice.