Seasonal dynamics and typology of microplastic pollution in Huixian karst wetland groundwater: Implications for ecosystem health.

This study offers an insightful and detailed examination of microplastic pollution in the Huixian karst wetland's groundwater, providing novel insights into the complex interplay of microplastic characteristics and their seasonal dynamics. We meticulously quantified microplastic concentrations, observing significant seasonal variation with values ranging from 4.9 to 13.4 n·L-1 in the wet season and 0.53-49.4 n·L-1 in the dry season. Our analysis pinpoints human activities and atmospheric deposition as key contributors to this contamination. A critical finding of our research is the pronounced disparity in microplastic levels between open wells and covered artesian wells, highlighting the vulnerability of open wells to higher pollution levels. Through correlation analysis, we unearthed the crucial influence of the karst region's unique hydrogeological characteristics on microplastic migration, distinctively different from non-karst areas. The karst terrain, characterized by its caves and subterranean rivers, facilitates the downward movement of microplastics from surface to groundwater, exacerbating pollution levels. Our investigation identifies agricultural runoff and domestic wastewater as primary pollution sources. These findings not only underscore the urgent need for environmental stewardship in karst regions but also provide a crucial foundation for formulating effective strategies to mitigate microplastic pollution in karst groundwater. The implications of this study extend beyond the Huixian karst wetland, offering a template for addressing microplastic pollution in similar ecosystems globally.

4-Coumarate-CoA ligase (4-CL) enhances flavonoid accumulation, lignin synthesis, and fruiting body formation in Ganoderma lucidum.

It is now understood that 4-Coumarate-CoA ligases (4-CL) are pivotal in bridging the phenylpropanoid metabolic pathway and the lignin biosynthesis pathway in plants. However, limited information on 4-CL genes and their functions in fungi is available. In this study, we cloned the 4-CL gene (Gl21040) from Ganoderma lucidum, which spans 2178 bp and consists of 10 exons and 9 introns. We also developed RNA interference and overexpression vectors for Gl21040 to investigate its roles in G. lucidum. Our findings indicated that in the Gl21040 interference transformants, 4-CL enzyme activities decreased by 31 %-57 %, flavonoids contents decreased by 10 %-22 %, lignin contents decreased by 20 %-36 % compared to the wild-type (WT) strain. Conversely, in the Gl21040 overexpression transformants, 4-CL enzyme activity increased by 108 %-143 %, flavonoids contents increased by 8 %-37 %, lignin contents improved by 15 %-17 % compared to the WT strain. Furthermore, primordia formation was delayed by approximately 10 days in the Gl21040-interferenced transformants but occurred 3 days earlier in the Gl21040-overexpressed transformants compared to the WT strain. These results underscored the involvement of the Gl21040 gene in flavonoid synthesis, lignin synthesis, and fruiting body formation in G. lucidum.

Transcriptome and metabolome analyses reveal transcription factors regulating ganoderic acid biosynthesis in Ganoderma lucidum development.

Ganoderma lucidum is an important medicinal fungus in Asian countries. Ganoderic acid (GA) is the major variety of bioactive and medicative components in G. lucidum. Biosynthesis of secondary metabolites is usually associated with cell differentiation and development. However, the mechanism underlying these phenomena remain unclear. Transcription factors play an essential regulatory role in the signal transduction pathway, owing to the fact that they represent the major link between signal transduction and expression of target genes. In the present study, we performed transcriptome and metabolome analyses to identify transcription factors involved in GA biosynthesis during development of G. lucidum. Transcriptome data revealed differentially expressed genes between mycelia and primordia, as well as between mycelia and the fruiting body. Results from gene ontology enrichment analysis and metabolome analyses suggested that GAs and flavonoids biosynthetic process significantly changed during fungal development. The analysis of predicted occurrences of DNA-binding domains revealed a set of 53 potential transcription factor families in G. lucidum. Notably, we found homeobox transcription factor and velvet family protein played important role in GA biosynthesis. Combined with previous studies, we provided a model diagram of transcription factors involved in GA biosynthesis during fruiting body formation. Collectively, these results are expected to enhance our understanding into the mechanisms underlying secondary metabolite biosynthesis and development in fungi.

Integrated Transcriptomics and Nontargeted Metabolomics Analysis Reveal Key Metabolic Pathways in Ganoderma lucidum in Response to Ethylene.

Ganoderic acid (GA) is an important secondary metabolite of Ganoderma lucidum with a diverse array of pharmacological properties. In this study, we found that exogenous ethylene increased the production of endogenous ethylene and ganoderic acid in G. lucidum. However, the mechanism by which ethylene is regulated remains unclear. As a result, we performed a combined transcriptomics and nontargeted metabolomics analysis to evaluate the regulatory mechanism of ethylene. A total of 4070 differentially expressed genes (1835 up-regulated and 2235 down-regulated) and 378 differentially accumulated metabolites (289 up-regulated and 89 down-regulated) were identified in all groups. The transcriptomics and nontargeted metabolomics data revealed that genes involved in the tricarboxylic acid (TCA) cycle, polyamine metabolic pathway, acetyl-CoA carboxylase (ACC) pathway, and triterpenoid metabolism were up-regulated, whereas the metabolic intermediates involved in these metabolic pathways were down-regulated. These findings imply that ethylene potentially accelerates normal glucose metabolism, hence increasing the number of intermediates available for downstream biological processes, including polyamine metabolism, ethylene synthesis pathway, and ganoderic acid biosynthesis. The findings will contribute significantly to our understanding of secondary metabolites biosynthesis in fungi.

Development of Serotype-Specific PCR Assays for Typing of Haemophilus parasuis Isolates Circulating in Southern China.

The bacterium Haemophilus parasuis is the specific pathogenic cause of Glässer's disease in swine. Fifteen serotypes of H. parasuis have been reported. A method to serotype H. parasuis isolates accurately would help to prevent and control Glässer's disease outbreaks through appropriate vaccination and to understand the epidemiology in specific geographic areas. However, according to traditional serotyping, the rate of nontypeable (NT) strains is 10 to 40%, which gives low accuracy. In the present study, we developed a set of PCR assays that are able to identify all the currently known H. parasuis serotypes, with a detection limit of 5 CFU. This PCR method is particularly useful to distinguish serotype 5 from serotype 12. We then surveyed the serotype prevalence of H. parasuis isolates from southern China using both the traditional indirect hemagglutination (IHA) and current PCR methods. Of the 298 isolates tested, 228 (76.51%) and 281 (94.30%) were serotyped by the IHA and PCR tests, respectively, with a concordance rate of 80.87% (241/298). The most prevalent serotypes obtained by PCR were 4, 5, 12, 13, NT, and 2, and the most prevalent obtained by IHA were NT, 5, 4, 12, 13, and 2. In conclusion, the PCR assays developed in this study provide a rapid and specific method for the molecular serotyping of H. parasuis.

Complete Genome Sequence of CHYJ130330, a Highly Virulent Strain of Porcine Epidemic Diarrhea Virus in South China.

Porcine epidemic diarrhea virus (PEDV) strain CHYJ130330 was isolated from southern China and shown to be highly virulent when inoculated into neonatal pigs. This report describes the complete genome sequence of CHYJ130330. These data will provide important insights into the variation of PEDV in China.