Microbiota characterization of the green mussel Perna viridis at the tissue scale and its relationship with the environment.

Research on the microbiota associated with marine invertebrates is important for understanding host physiology and the relationship between the host and the environment. In this study, the microbiota of the green mussel Perna viridis was characterized at the tissue scale using 16S rRNA gene high-throughput sequencing and compared with the microbiota of the surrounding environment. Different mussel tissues were sampled, along with two environmental samples (the mussel's attachment substratum and seawater). The results showed that the phyla Proteobacteria, Bacteroidetes, and Spirochaetae were dominant in mussel tissues. The bacterial community composition at the family level varied among the tissues of P. viridis. Although the microbiota of P. viridis clearly differed from that of the surrounding seawater, the composition and diversity of the microbial community of the foot and outer shell surface were similar to those of the substratum, indicating their close relationship with the substratum. KEGG prediction analysis indicated that the bacteria harbored by P. viridis were enriched in the degradation of aromatic compounds, osmoregulation, and carbohydrate oxidation and fermentation, processes that may be important in P. viridis physiology. Our study provides new insights into the tissue-scale characteristics of mussel microbiomes and the intricate connection between mussels and their environment.

New genes helped acorn barnacles adapt to a sessile lifestyle.

Barnacles are the only sessile lineages among crustaceans, and their sessile life begins with the settlement of swimming larvae (cyprids) and the formation of protective shells. These processes are crucial for adaptation to a sessile lifestyle, but the underlying molecular mechanisms remain poorly understood. While investigating these mechanisms in the acorn barnacle, Amphibalanus amphitrite, we discovered a new gene, bcs-6, which is involved in the energy metabolism of cyprid settlement and originated from a transposon by acquiring the promoter and cis-regulatory element. Unlike mollusks, the barnacle shell comprises alternate layers of chitin and calcite and requires another new gene, bsf, which generates silk-like fibers that efficiently bind chitin and aggregate calcite in the aquatic environment. Our findings highlight the importance of exploring new genes in unique adaptative scenarios, and the results will provide important insights into gene origin and material development.

Rapid discovery of a new antifoulant: From in silico studies targeting barnacle chitin synthase to efficacy against barnacle settlement.

Due to the adverse environmental impacts of toxic heavy metal-based antifoulants, the screening of environmentally friendly antifoulants has become important for the development of marine antifouling technology. Compared with the traditional lengthy and costly screening method, computer-aided drug design (CADD) offers a promising and efficient solution that can accelerate the screening process of green antifoulants. In this study, we selected barnacle chitin synthase (CHS, an important enzyme for barnacle settlement and development) as the target protein for docking screening. Three CHS genes were identified in the barnacle Amphibalanus amphitrite, and their encoded proteins were found to share a conserved glycosyltransferase domain. Molecular docking of 31,561 marine natural products with AaCHSs revealed that zoanthamine alkaloids had the best binding affinity (-11.8 to -12.6 kcal/mol) to AaCHSs. Considering that the low abundance of zoanthamine alkaloids in marine organisms would limit their application as antifoulants, a marine fungal-derived natural product, mycoepoxydiene (MED), which has a similar chemical structure to zoanthamine alkaloids and the potential for large-scale production by fermentation, was selected and validated for stable binding to AaCHS2L2 using molecular docking and molecular dynamics simulations. Finally, the efficacy of MED in inhibiting cyprid settlement of A. amphitrite was confirmed by a bioassay that demonstrated an EC50 of 1.97 µg/mL, suggesting its potential as an antifoulant candidate. Our research confirmed the reliability of using AaCHSs as antifouling targets and has provided insights for the efficient discovery of green antifoulants by CADD.

Impacts of ocean acidification and warming on the release and activity of the barnacle waterborne settlement pheromone, adenosine.

The effects of ocean acidification (OA) and warming on the physiological processes of many marine species have been well documented. However, far less is known about the impacts of these global variables on chemical communication. In this study, we identified the barnacle waterborne settlement pheromone (BWSP) of Balanus albicostatus as adenosine (Ado). Our results showed that neither elevated temperature (30 °C vs. ambient 26 °C) nor elevated pCO2 (1000 µatm vs. ambient 400 µatm) significantly affected the release of Ado from B. albicostatus adults. Exposure to elevated temperature and OA did not impair larval cue perception for settlement in B. albicostatus; however, OA inhibited settlement under elevated temperature in the absence/presence of BWSP, and elevated temperature induced larval settlement only in the presence of BWSP under ambient pCO2 condition. These results provided important insights into barnacle aggregation behavior in changing oceans and may help to predict the consequences of climate change on barnacle populations.

Functional validation of CYP304A1 associated with haedoxan A detoxification in Aedes albopictus by RNAi and transgenic drosophila.

BACKGROUND: Insect cytochrome P450 monooxygenases play important roles in the detoxification metabolism of endogenous and exogenous compounds. Haedoxan A (HA) from Phryma leptostachya L. is a highly efficient natural pesticide used to control houseflies and mosquitos. CYP4C21 and CYP304A1 were previously demonstrated to be transcriptionally increased in Aedes albopictus in response to HA exposure, but their involvement in HA metabolism is unknown. RESULTS: Our data showed that CYP304A1 expression levels in A. albopictus were highest in third-instar larvae, and the expression level of CYP4C21 decreased significantly with the growth of instars, with the lowest occurring in the pupal stage. Compared with the control, the silencing of CYP304A1 and CYP4C21 genes by chitosan nanoparticle-mediated RNA interference could deplete 58.2% and 54.0% of the expression of corresponding genes, respectively. The bioassay data showed that knocking down the expression of CYP304A1 increased the mortality of A. albopictus when exposed to HA at LC30 and LC50 doses, but did not significantly increase mortality after silencing CYP4C21. Our data demonstrated that CYP304A1, but not CYP4C21, may be involved in HA detoxification. Moreover, the resistance ratio of CYP304A1 overexpressing flies was approximately 2-fold higher than that of the control line. The metabolized product of HA by CYP304A1 needs to be further confirmed by in vitro expression. CONCLUSION: This finding showed that inducibility was not always linked to detoxifying capabilities, and enhanced our understanding of the molecular basis of HA metabolic detoxification in A. albopictus. © 2022 Society of Chemical Industry.

Does retail investors beat institutional investors?--Explanation of game stop's stock price anomalies.

This paper studies the relation of information cost, retail investor sentiment and asset pricing. Our motivation to study this model is to learn why retail investors could move asset price away from fundamental values. In the model, the institutional investors are pessimistic and the retail investors are optimistic, the ratio of the expected utility of informed and rational but uninformed institutional investors increases first and then decreases as the cost of information increases. In addition, a large number of retail investors promoted substantial increases in stock prices. This model provides part of the explanation for the unusually high stock price of Game Stop in early 2021 that retail investors cliqued and confronted institutional investors.

Simultaneous Regulation of Solvation Shell and Oriented Deposition toward a Highly Reversible Fe Anode for All-Iron Flow Batteries.

Developing low-cost all-iron hybrid redox flow batteries (RFBs) presents a practical alternative to the high-cost all-vanadium RFBs and is deemed vital for grid-scale energy storage applications. However, the intrinsically poor Fe anode reversibility associated with the deposition and dissolution of metallic iron greatly limits the cycling performance and long-term stability of all-iron hybrid RFBs. Herein, a highly reversible and dendrite-free Fe anode is reported for all-iron RFBs through regulation of polar solvent dimethyl sulfoxide (DMSO) on FeCl2 anolyte, which simultaneously reshapes Fe2+ solvation structure and induces controllable oriented Fe deposition. Combining both experimental and theoretical analyses, the polar DMSO additives prove effective in replacing H2 O molecule from the primary solvation shell of Fe2+ cation via the Fe2+ -O (DMSO) bond and meanwhile induces a fine-grained Fe nucleation on the preferred Fe (110) plane, which are responsible for the minimized hydrogen evolution and dendrite-free Fe deposition that significantly enhance Fe anode reversibility. The all-iron RFB based on the proposed FeCl2 -DMSO anolyte demonstrates an excellent combination of peak power density of 134 mW cm-2 , high energy efficiency of 75% at 30 mA cm-2 , and high capacity retention of 98.6% over 200 cycles, which presents the best performance of all-iron RFBs among previously reported research.

The degradation and environmental risk of camptothecin, a promising marine antifoulant.

Given the adverse environmental impacts of the antifoulants currently used in marine antifouling paints, such as copper and booster biocides, it is urgent to identify potential substitutes that are environmentally benign. Here, we examined the degradation of camptothecin (a natural product previously identified as an efficient antifoulant in the laboratory and in the field) under various conditions and evaluated the environmental risks associated with its use as a marine antifoulant. We found that camptothecin was rapidly photolyzed in seawater: the half-life of camptothecin was less than 1 d under a light intensity of 1000-20,000 lx and was approximately 0.17 d under sunlight irradiation. At pH 4 and pH 7, camptothecin had half-lives of 30.13 and 16.90 d, respectively; at 4 °C, 25 °C, and 35 °C, the half-lives of camptothecin were 23.90, 21.66, and 26.65 d, respectively. Camptothecin biodegradation in seawater was negligible. The predicted no-effect concentration (PNEC) of camptothecin was 2.19 × 10-1 µg L-1, while the average predicted environmental concentrations (PECs) in open seas, shipping lanes, commercial harbors, and marinas were 6.14 × 10-7, 9.39 × 10-7, 6.80 × 10-3, and 5.03 × 10-2 µg L-1, respectively. The PEC/PNEC ratio of camptothecin was much lower than 1 (i.e., 2.80 × 10-6, 4.29 × 10-6, 3.11 × 10-2, and 2.30 × 10-1 for open seas, shipping lanes, commercial harbors, and marinas, respectively), indicating that the use of camptothecin as a marine antifoulant posed little environmental risk.

Adenosine Triggers Larval Settlement and Metamorphosis in the Mussel Mytilopsis sallei through the ADK-AMPK-FoxO Pathway.

Settlement and metamorphosis of planktonic larvae into benthic adults are critical components of a diverse range of marine invertebrate-mediated processes such as the formation of mussel beds and coral reefs, the recruitment of marine shellfisheries, and the initiation of macrobiofouling. Although larval settlement and metamorphosis induced by natural chemical cues is widespread among marine invertebrates, the mechanisms of action remain poorly understood. Here, we identified that the molecular target of adenosine (an inducer of larval settlement and metamorphosis from conspecific adults in the invasive biofouling mussel Mytilopsis sallei) is adenosine kinase (ADK). The results of transcriptomic analyses, pharmacological assays, temporal and spatial gene expression analyses, and siRNA interference, suggest that ATP-dependent phosphorylation of adenosine catalyzed by ADK activates the downstream AMPK-FoxO signaling pathway, inducing larval settlement and metamorphosis in M. sallei. This study not only reveals the role of the ADK-AMPK-FoxO pathway in larval settlement and metamorphosis of marine invertebrates but it also deepens our understanding of the functions and evolution of adenosine signaling, a process that is widespread in biology and important in medicine.

Transcriptome Analysis of Aedes albopictus (Diptera: Culicidae) Larvae Exposed With a Sublethal Dose of Haedoxan A.

Aedes albopictus is the vector of arbovirus diseases including yellow fever, dengue, Zika virus, and chikungunya fever, and it poses an enormous threat to human health worldwide. Previous studies have revealed that haedoxan A (HA), which is an insecticidal sesquilignan from Phryma leptostachya L., is a highly effective natural insecticide for managing mosquitoes and houseflies; however, the mechanisms underlying the response of Ae. albopictus after treatment with sublethal concentrations of HA is not clear. Here, high-throughput sequencing was used to analyze the gene expression changes in Ae. albopictus larvae after treatment with the LC30 of HA. In total, 416 differentially expressed genes (DEGs) were identified, including 328 upregulated genes and 88 downregulated genes. Identification and verification of related DEGs were performed by RT-qPCR. The results showed that two P450 unigenes (CYP4C21 and CYP304A1), one carboxylesterase, and one ABC transporter (ABCG1) were induced by HA, which indicated that these detoxifying enzyme genes might play a major role in the metabolic and detoxification processes of HA. Additionally, acetylcholine receptor subunit ɑ2 (AChRα2), AChRα5, AChRα9, and the glutamate receptor ionotropic kainate 2 (GRIK2) were found to be upregulated in HA-treated larvae, suggesting that HA affected the conduction of action potentials and synaptic transmission by disrupting the function of neural receptors. These results provide a foundation for further elucidating the target of HA and the mechanism of detoxification metabolism in Ae. albopictus.

Flow Field Perception of a Moving Carrier Based on an Artificial Lateral Line System.

At present, autonomous underwater vehicles (AUVs) cannot perceive local environments in complex marine environments, where fish can obtain hydrodynamic information about the surrounding environment through a lateral line. Inspired by this biological function, an artificial lateral line system (ALLS) was built on a moving bionic carrier using the pressure sensor in this paper. When the carrier operated with different speeds in the flow field, the pressure distribution characteristics surrounding the carrier were analyzed by numerical simulation, where the effect of the flow angle between the fluid velocity direction and the carrier navigation direction was considered. The flume experiment was carried out in accordance with the simulation conditions, and the analysis results of the experiment were consistent with those in the simulation. The relationship between pressure and fluid velocity was established by a fitting method. Subsequently, the pressure difference method was investigated to establish a relationship model between the pressure difference on both sides of the carrier and the flow angle. Finally, a back propagation neural network model was used to predict the fluid velocity, flow angle, and carrier speed successfully in the unknown fluid environment. The local fluid environment perception by moving carrier carrying ALLS was studied which may promote the engineering application of the artificial lateral line in the local perception, positioning, and navigation on AUVs.

Endophytic Bacillus megaterium BM18-2 mutated for cadmium accumulation and improving plant growth in Hybrid Pennisetum.

Hybrid Pennisetum (Pennisetum americanum × P. purpureum Schumach L.) is a tall and rapidly growing perennial C4 bunch grass. It has been considered as a promising plant for phytoremediation of heavy metal-contaminated soil due to its high biomass, high resistance to environmental stress, pests and diseases. Heavy metal bioavailability level is the most important parameter for measurement of the phytoremediation efficiency. Endophytic bacteria were used to further enhance phytoremediation of heavy metals through bioaccumulation or bioabsorption process. In the present study, the endophytic Bacillus megaterium strain 'BM18' isolated from hybrid Pennisetum was screened under 10-70 µM cadmium (Cd) stress for Cd-resistant mutant colonies. And one such mutant colony'BM18-2' was obtained from the screen. Comparably, 'BM18-2' was more Cd-tolerant and had higher Cd removal ability than the original strain'BM18'. The amount of IAA and ammonia production, and phosphate solubilization were 1.09, 1.23 and 1.24 times in 'BM18-2' than those of 'BM18', respectively. Full genome sequencing of these two strains revealed 6 different genes: BM18GM000901, BM18GM005669 and BM18GM005870 encoding heavy metal efflux pumps, BM18GM003487 and BM18GM005818 encoding transcriptional regulators for metal stress biosensor and BM18GM001335 encoding a replication protein. Inoculation with 'BM18-2' or 'BM18' both significantly reduced the toxic effect of Cd on hybrid Pennisetum, while the effect of 'BM18-2' on plant growth promotion in the presence of Cd was significantly better that of 'BM18'. Therefore, the mutated strain 'BM18-2' could be used as a potential agent for Cd bioremediation, improving growth and Cd absorption of hybrid Pennisetum in Cd contaminated soil.

Positive impacts of early auditory training on cortical processing at an older age.

Progressive negative behavioral changes in normal aging are paralleled by a complex series of physical and functional declines expressed in the cerebral cortex. In studies conducted in the auditory domain, these degrading physical and functional cortical changes have been shown to be broadly reversed by intensive progressive training that improves the spectral and temporal resolution of acoustic inputs and suppresses behavioral distractors. Here we found older rats that were intensively trained on an attentionally demanding modulation-rate recognition task in young adulthood substantially retained training-driven improvements in temporal rate discrimination abilities over a subsequent 18-mo epoch-that is, forward into their older age. In parallel, this young-adult auditory training enduringly enhanced temporal and spectral information processing in their primary auditory cortices (A1). Substantially greater numbers of parvalbumin- and somatostatin-labeled inhibitory neurons (closer to the numbers recorded in young vigorous adults) were recorded in the A1 and hippocampus in old trained versus untrained age-matched rats. These results show that a simple form of training in young adulthood in this rat model enduringly delays the otherwise expected deterioration of the physical status and functional operations of the auditory nervous system, with evident training impacts generalized to the hippocampus.

Using CRISPR/Cas9 for Large Fragment Deletions in Saccharomyces cerevisiae.

CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9) systems have emerged as a powerful tool for genome editing in many organisms. The wide use of CRISPR/Cas9 systems may be due to the fact that these systems contain a simple guide RNA (sgRNA) that is relatively easy to design and they are very versatile with the ability to simultaneously target multiple genes within a cell ( Varshney et al., 2015 ). We have developed a CRISPR/Cas9 system to delete large genomic fragments (exceeding 30 kb) in Saccharomyces cerevisiae. One application of this technology is to study the effects of large-scale deletions of non-essential genes which may give insight into the function of gene clusters within chromosomes at the molecular level. In this protocol, we describe the general procedures for large fragment deletion in S. cerevisiae using CRISPR/Cas9 including: how to design CRISPR arrays and how to construct Cas9-crRNA expression plasmids as well as how to detect mutations introduced by the system within S. cerevisiae cells.

Large fragment deletion using a CRISPR/Cas9 system in Saccharomyces cerevisiae.

Large chromosomal modifications have been performed in natural and laboratory evolution studies and hold tremendous potential for use in foundational research, medicine, and biotechnology applications. Recently, the type II bacterial Clustered Regularly Interspaced Short Palindromic Repeat and CRISPR-associated (CRISPR/Cas9) system has emerged as a powerful tool for genome editing in various organisms. In this study, we applied the CRISPR/Cas9 system to preform large fragment deletions in Saccharomyces cerevisiae and compared the performance activity to that of a traditional method that uses the Latour system. Here we report in S. Cerevisiae the CRIPR/Cas9 system has been used to delete fragments exceeding 30 kb. The use of the CRISPR/Cas9 system for generating chromosomal segment excision showed some potential advantages over the Latour system. All the results indicated that CRISPR/Cas9 system was a rapid, efficient, low-cost, and versatile method for genome editing and that it can be applied in further studies in the fields of biology, agriculture, and medicine.

Environmental Controls Over Actinobacteria Communities in Ecological Sensitive Yanshan Mountains Zone.

The Yanshan Mountains are one of the oldest mountain ranges in the world. They are located in an ecologically sensitive zone in northern China near the Hu Huanyong Line. In this metagenomic study, we investigated the diversity of Actinobacteria in soils at 10 sites (YS1-YS10) on the Yanshan Mountains. First, we assessed the effect of different soil prtreatment on Actinobacteria recovery. With the soil pretreatment method: air drying of the soil sample, followed by exposure to 120°C for 1 h, we observed the higher Actinobacteria diversity in a relatively small number of clone libraries. No significant differences were observed in the Actinobacterial diversity of soils from sites YS2, YS3, YS4, YS6, YS8, YS9, or YS10 (P > 0.1). However, there were differences (P < 0.05) from the YS7 site and other sites, especially in response to environmental change. And we observed highly significant differences (P < 0.001) in Actinobacterial diversity of the soil from YS7 and that from YS4 and YS8 sites. The climatic characteristics of mean active accumulated temperature, annual mean precipitation, and annual mean temperature, and biogeochemical data of total phosphorus contributed to the diversity of Actinobacterial communities in soils at YS1, YS3, YS4, and YS5 sites. Compared to the climatic factors, the biogeochemical factors mostly contributed in shaping the Actinobacterial community. This work provides evidence that the diversity of Actinobacterial communities in soils from the Yashan Mountains show regional biogeographic patterns and that community membership change along the north-south distribution of the Hu Huanyong Line.