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\nIntroduction: Asthma is a common chronic respiratory disease characterized by chronic airway inflammation and abnormal airway remodeling. The RhoA/ROCK pathway and myocardin-related transcription factor A (MRTF-A) demonstrate significant associations with the proliferation of airway smooth muscle cells (ASCMs), which tightly correlates with the process of airway remodeling. MYOCD, which is homologous to MRTF-A but specifically expressed in smooth muscle cells, potentially regulates RhoA/ROCK activated cell proliferation and subsequent airway remodeling. Methods: The RhoA/ROCK overexpression and silencing cell lines were constructed in vitro, as well as MYOCD overexpression/silencing. The cytoskeleton alterations induced by RhoA/ROCK pathway were identified by the measuring of globular actin and filamentous actin. Results: The comparison between controls for overexpression/silencing and ROCK overexpression/silencing revealed that MYOCD presented consistent change trends with cytoskeleton and RhoA/ROCK pathway. The ROCK1 facilitates the proliferation and migration of ASCMs. The MYOCD enhanced the proliferation and migration of HASMCs. Conclusion: Our study indicates that Rho/ROCK/MYOCD is a key pathway involved in the migration and proliferation of airway smooth muscle cells. Inhibition of Rho/ROCK may be an effective approach to breaking the vicious cycle of asthmatic ASCMs proliferation, providing a novel strategy in treating asthma airway remodeling. Asthma is a common chronic respiratory disease characterized by chronic airway inflammation and abnormal airway remodeling. The regulation process of RhoA/ROCK signaling pathway and downstream MRTF-A gene is well studied and exhibits significant associations with cell contraction and cell proliferation, which correlates tightly with airway remodeling. While most studies focusing on the MRTF-A to clarify the mechanism of cell growth, we paid close attention to MYOCD gene, which shares homology with MRTF-A but expressed specifically in smooth muscle cells. Through the series cell experiments, molecular assays, and literature review, we firstly illustrated the potential function of MYOCD underlying the regulation of RhoA/ROCK activated cell proliferation and subsequent airway remodeling in airway smooth muscle cells. This novel sight provides therapeutic targets for asthma. [ABSTRACT FROM AUTHOR]

The plethora of genome sequences produced in the postgenomic age has not resolved many of our most pressing biological questions. Correlating gene expression with an interrogatable and easily observable characteristic such as the surrogate phenotype conferred by a reporter gene is a valuable approach to gaining insight into gene function. Many reporters including lacZ, amdS, and the fluorescent proteins mRuby3 and mNeonGreen have been used across all manners of organisms. Described here is an investigation into the creation of a robust, synthetic, fusion reporter system for Cryptococcus neoformans that combines some of the most useful fluorophores available in this system with the versatility of the counter-selectable nature of amdS. The reporters generated include multiple composition and orientation variants, all of which were investigated for differences in expression. Evaluation of known promoters from the TEF1 and GAL7 genes was undertaken, elucidating novel expression tendencies of these biologically relevant C. neoformans regulators of transcription. Smaller than lacZ but providing multiple useful surrogate phenotypes for interrogation, the fusion ORF serves as a superior whole-cell assay compared to traditional systems. Ultimately, the work described here bolsters the array of relevant genetic tools that may be employed in furthering manipulation and understanding of the WHO fungal priority group pathogen C. neoformans. [ABSTRACT FROM AUTHOR]

The Spt-Ada-Gcn Acetyltransferase (SAGA) complex is a highly conserved co-activator found across eukaryotes. It is composed of a number of modules which can vary between species, but all contain the core module. Hfi1 (known as TADA1 in Homo sapiens) is one of the proteins that forms the core module, and has been shown to play an important role in maintaining complex structural integrity in both brewer's yeast and humans. In this study we successfully identified the gene encoding this protein in the important fungal pathogen, Cryptococcus neoformans, and named it HFI1. The hfi1Δ mutant is highly pleiotropic in vitro, influencing phenotypes, ranging from temperature sensitivity and melanin production to caffeine resistance and titan cell morphogenesis. In the absence of Hfi1, the transcription of several other SAGA genes is impacted, as is the acetylation and deubiquination of several histone residues. Importantly, loss of the gene significantly impacts virulence in a murine inhalation model of cryptococcosis. In summary, we have established that Hfi1 modulates multiple pathways that directly affect virulence and survival in C. neoformans, and provided deeper insight into the importance of the non-enzymatic components of the SAGA complex. [ABSTRACT FROM AUTHOR]

Ammonia oxidation, the first and rate‐limiting step in nitrification, plays a critical role in the nitrogen cycle. However, the links between the dynamics of ammonia‐oxidizing communities and ecosystem processes along the estuarine salinity gradient remain uncertain. In this study, we examined the diversity, abundance, and community structure of ammonia‐oxidizing prokaryotes, and the potential nitrification rates along the Yangtze estuarine salinity gradient. Phylogenetic analysis showed that the predominant ammonia‐oxidizing bacteria (AOB) and ammonia‐oxidizing archaea (AOA) fell within the Nitrosospira and Nitrosopumilus clusters, respectively. The AOB amoA gene abundance (4.67 × 105 to 3.90 × 107 copies per gram of dry sediment) outnumbered AOA (5.14 × 104 to 8.88 × 106 copies per gram of dry sediment). The potential nitrification rates varied between 0.13 and 0.63 μg N·g−1·day−1 and related only to AOA amoA gene abundance. Salinity had significant effects on AOA amoA gene abundance, nitrification rates, and the community structure of ammonia‐oxidizing prokaryotes. Principal coordinate analysis showed that the AOB amoA gene clones derived from the middle‐ and high‐salinity regions behaved as a cohesive group, while all the low‐salinity clone libraries were grouped together. Moreover, the distribution of AOA communities showed a distinct salinity differentiation. Overall, this study improves the understanding of the dynamic shifts in ammonia‐oxidizing microorganisms in the Yangtze Estuary. Key Points: Significant shifts in ammonia‐oxidizing community structure were found along the salinity gradientBoth of AOA amoA gene abundance and potential nitrification rates were significantly and negatively correlated with salinityPotential nitrification rates were significantly related to AOA amoA gene abundance, but not with AOB [ABSTRACT FROM AUTHOR]

Dissimilatory nitrate reduction to ammonium (DNRA) plays an important role in regulating the fate of reactive nitrogen in estuarine and coastal ecosystems. In this work, intertidal sediments of the Yangtze Estuary were collected in January and August 2015. Potential rates of DNRA and associated functional gene were investigated with nitrogen isotope-tracing and molecular techniques. The measured DNRA rates ranged from 0.14 to 5.57 μmol 15N kg−1 h−1 in the intertidal sediments. DNRA rates were tightly related to abundance of nrfA gene ( p < 0.001), demonstrating that fermentation reaction may be the dominant pathway of DNRA in the study area. Redundancy analysis (RDA) showed a relationship between DNRA and organic matter and NO2−, suggesting that these substrates stimulated the metabolism of DNRA microorganisms. On the other hand, the correlation between abundances of nrfA gene and Fe2+ and sulfide in the RDA analysis implied that oxidation of both Fe2+ and sulfide can enhance fermentative DNRA by providing extra free energy. DNRA converted approximately 2.29 × 105 t of nitrate to ammonia annually in the sampling area of the Yangtze Estuary, and most of the converted ammonium was retained in the estuarine ecosystem. DNRA may further contribute to eutrophication in the Yangtze Estuary and also in the other hypereutrophic estuaries. [ABSTRACT FROM AUTHOR]

Denitrification is a dominant reactive nitrogen removal pathway in most estuarine and coastal ecosystems, and plays a significant role in regulating N 2 O release. Although multiple antibiotics residues are widely detected in aquatic environment, combined effects of antibiotics on denitrification remain indistinct. In this work, 5 classes of antibiotics (sulfonamides, chloramphenicols, tetracyclines, macrolides, and fluoroquinolones) were selected to conduct orthogonal experiments in order to explore their combined effects on denitrification. 15 N-based denitrification and N 2 O release rates were determined in the orthogonal experiments, while denitrifying functional genes were examined to illustrate the microbial mechanism of the combined antibiotics effect. Denitrification rates were inhibited by antibiotics treatments, and synergistic inhibition effect was observed for multiple antibiotics exposure. Different classes of antibiotics had different influence on N 2 O release rates, but multiple antibiotics exposure mostly led to stimulatory effect. Abundances of denitrifying functional genes were inhibited by multiple antibiotics exposure due to the antimicrobial properties, and different inhibition on denitrifiers may be the major mechanism for the variations of N 2 O release rates. Combined effects of antibiotics on denitrification may lead to nitrate retention and N 2 O release in estuarine and coastal ecosystems, and consequently cause cascading environmental problems, such as greenhouse effects and hyper-eutrophication. [ABSTRACT FROM AUTHOR]

Background: Oviposition site selection is an important factor in determining the success of insect populations. Orius spp. are widely used in the biological control of a wide range of soft-bodied insect pests such as thrips, aphids, and mites. Orius strigicollis (Heteroptera: Anthocoridae) is the dominant Orius species in southern China; however, what factor drives its selection of an oviposition site after mating currently remains unknown., Methods: Here, kidney bean pods (KBPs) were chosen as the oviposition substrate, and choice and nonchoice experiments were conducted to determine the preferences concerning oviposition sites on the KBPs of O. strigicollis . The mechanism of oviposition behavior was revealed through observation and measurement of oviposition action, the egg hatching rate, and the oviposition time., Results: We found that O. strigicollis preferred the seams of the pods for oviposition, especially the seams at the tips of the KBPs. Choice and nonchoice experiments showed that females did not lay eggs when the KBP tail parts were unavailable. The rates of egg hatching on different KBP parts were not significantly different, but the time required for females to lay eggs on the tip seam was significantly lower. Decreased oviposition time is achieved on the tip seam because the insect can exploit support points found there and gain leverage for insertion of the ovipositor., Discussion: The preferences for oviposition sites of O. strigicollis are significantly influenced by the topography of the KBP surface. Revealing such behavior and mechanisms will provide an important scientific basis for the mass rearing of predatory bugs., Competing Interests: The authors declare there are no competing interests., (©2021 Yu et al.)

Silver nanoparticles (AgNPs) are the most common materials in nanotechnology-based consumer products globally. Because of the wide application of AgNPs, their potential environmental impact is currently a highly topical focus of concern. Nitrification is one of the processes in the nitrogen cycle most susceptible to AgNPs but the specific effects of AgNPs on nitrification in aquatic environments are not well understood. We report the influence of AgNPs on nitrification and associated nitrous oxide (N 2 O) production in estuarine sediments. AgNPs inhibited nitrification rates, which decreased exponentially with increasing AgNP concentrations. The response of nitrifier N 2 O production to AgNPs exhibited low-dose stimulation (<534, 1476, and 2473 μg liter -1 for 10-, 30-, and 100-nm AgNPs, respectively) and high-dose inhibition (hormesis effect). Compared with controls, N 2 O production could be enhanced by >100% at low doses of AgNPs. This result was confirmed by metatranscriptome studies showing up-regulation of nitric oxide reductase (norQ) gene expression in the low-dose treatment. Isotopomer analysis revealed that hydroxylamine oxidation was the main N 2 O production pathway, and its contribution to N 2 O emission was enhanced when exposed to low-dose AgNPs. This study highlights the molecular underpinnings of the effects of AgNPs on nitrification activity and demonstrates that the release of AgNPs into the environment should be controlled because they interfere with nitrifying communities and stimulate N 2 O emission.