Genome-wide transcriptomics and microRNAomics analyses uncover multi-faceted mechanisms to cope with copper stress in ancient macrobenthos amphioxus.

The mechanisms underlying the toxicity of environmental stress are unclear for marine macrobenthos. Copper/Cu has posed the most serious threats to amphioxus, an ancient and model benthic cephalochordate. Herein, a dynamic change in the physiological parameters (GR, SOD, ATP, and MDA) was detected with ROS accumulation in Branchiostoma belcheri exposed to 0.3 mg·L-1 Cu. Transcriptomes and microRNAomes of B. belcheri were generated to investigate the molecular mechanisms by which this amphioxus copes with Cu exposure. Time-specific genes identified at different time points after exposure were involved in the stimulus and immune response, detoxification and ionic homeostasis, aging and the nervous system, sequentially, with prolongation of exposure time, forming a dynamic process of molecular response to Cu stress. In total, 57 differentially expressed miRNAs were identified under Cu stress. Transcriptomics-miRNAomics analyses indicate that these miRNAs targeted genes associated with many key biological processes such as xenobiotics degradation, oxidative stress, and energy metabolism. The constructed miRNA-mRNA-pathway network uncovered a broad post-transcriptional regulatory mechanism in B. belcheri to cope with Cu stress. Overall, this integrated analyses show that enhanced defense response, accelerated ROS elimination, and repressed ATP production constitute a comprehensive strategy to cope with Cu toxicity in the ancient macrobenthos.

Antibacterial effect of bacteriocin XJS01 and its application as antibiofilm agents to treat multidrug-resistant Staphylococcus aureus infection.

Multidrug-resistant (MDR) Staphylococcus aureus biofilms have emerged as a serious threat to human health. Recently, the development of antibiotic replacement therapy has gained much attention due to the potential application of bacteriocin. The present study sought to evaluate the antibacterial effect of bacteriocin XJS01 against MDR S. aureus, a previously reported bacteriocin against S. aureus strain 2612:1606BL1486 (S. aureus_26, an MDR strain demonstrated here), and its potential application as an antibiofilm agent. The minimum bactericide concentration of XJS01 against MDR S. aureus_26 was 33.18 µg/mL. XJS01 exhibited excellent storage stability and resistance against acid and reduced the density of established MDR S. aureus_26 biofilm. The hemolytic and HEK293T cytotoxicity activities of XJS01 and the histological analyses in mice confirmed its safety. Moreover, XJS01 effectively disrupted the MDR S. aureus_26 biofilm established on the skin wound surface and reduced the biofilm-isolated bacteria, thereby decreasing the release of pro-inflammatory cytokines and the proliferation of alternatively activated macrophages. Compared to mupirocin, XJS01 exhibited an excellent therapeutic effect on mice skin wounds, confirming it to be a potential alternative to antibiotics.

Comparative transcriptomic analysis provides insights into antibacterial mechanisms of Branchiostoma belcheri under Vibrio parahaemolyticus infection.

Amphioxus, a basal chordate, is widely considered to be an existing proxy of the invertebrate ancestor of vertebrates, and it exhibits susceptibility to various pathogen infections and pathogenic mimic challenges. Here, in order to understand more clearly its antibacterial mechanisms, we analyzed the ribosomal RNA (rRNA)-depleted transcriptome of Chinese amphioxus (Branchiostoma belcheri) infected with Vibrio parahaemolyticus (V. p.) via next-generation deep sequencing technology (RNA-seq). We identified a total of 3214 differentially expressed genes (DEGs) by comparing V. p.-infected and control transcriptome libraries, including 2219 significantly up-regulated and 995 significantly down-regulated DEGs in V. p.-infected amphioxus. The DEGs with the top 10 most dramatic expression fold changes after V. p. infection, as well as 53 immune-related DEGs (IRDs) belonging to four primary categories of innate immunity were analyzed further. Through gene ontology (GO) and pathway enrichment analysis, DEGs were found to be primarily related to immune processes, apoptosis, catabolic and metabolic processes, binding and enzyme activity, while pathways involving bacterial infection, immune signaling, immune response, cancer, and apoptosis were overrepresented. We validated the RNA-seq results by detecting the expression levels of 10 IRDs using qRT-PCR, and we surveyed the dynamic variation in gene expression for these IRDs at 0, 6, 12, 24, and 48 h after V. p. TREATMENT: Subsequently, according to the RNA-seq results, the presence of a primitive Toll-like receptor (TLR)-mediated antibacterial immune signaling pathway was predicted in B. belcheri. This study provides valuable information regarding antibacterial immunity for further research into the evolution of immunity in vertebrates and broadens our understanding of the innate immune response against bacterial invasion in amphioxus.

Laceyella sediminis sp. nov., a thermophilic bacterium isolated from a hot spring.

A thermophilic bacterium, designated strain RHA1(T), was isolated from a sediment sample collected from a hot spring in Tengchong county, Yunnan province, south-west China, and was characterized by using a polyphasic approach. Based on its phenotypic and phylogenetic characteristics, strain RHA1(T) was affiliated to the genus Laceyella. The strain formed white aerial and yellow-white substrate mycelia, bearing single endospores on short sporophores. The cell-wall peptidoglycan contained meso-diaminopimelic acid. Whole-cell hydrolysates contained ribose and glucose. The major fatty acids were iso-C(15:0) (62.39%) and anteiso-C(15:0) (17.55%)(.) The predominant menaquinone was MK-9. The G+C content of the genomic DNA of strain RHA1(T) was 47.9 mol%. Based on DNA-DNA hybridization data, chemotaxonomic characteristics and differential physiological properties, strain RHA1(T) is considered to represent a novel species of the genus Laceyella, for which the name Laceyella sediminis sp. nov. is proposed; the type strain is RHA1(T) (=DSM 45263(T)=CCTCC AA 208058(T)).