Biological characterization and genomic analysis of a novel methicillin-resistant Staphylococcus aureus phage, SauPS-28.

Staphylococcus aureus, a representative gram-positive bacterium, is a common infectious pathogen widely present in the natural environment. The increasing application of antibiotics is witnessing an increment in the number of clinically resistant strains (such as methicillin-resistant S. aureus [MRSA]), which has posed a great challenge to antimicrobial therapy. In this study, a novel MRSA phage, SauPS-28, was isolated from the lake water of the Guangxi Zhuang Autonomous Region. This phage has an incubation period of approximately 30 min, a lysis period of approximately 40 min, and a burst size of approximately 25 PFU/cell. The isolated phage exhibited good biological stability at a pH range of 6.0-9.0 and temperature range of 4°C-37°C. In addition, the identification of an elongated tail using transmission electron microscopy confirmed that SauPS-28 belongs to the long-tailed phage family. Whole-genome sequencing analysis revealed that SauPS-28 has a 43,286-bp-long genome with 31.03% G + C content. Moreover, SauPS-28 exhibited 95.69% sequence identity with ECel-2020k, while the query coverage was only 66%, which is a newly discovered phage. Whole-genome functional annotation results revealed that SauPS-28 had 68 open reading frames (ORFs). Of these, 30 ORFs are unknown proteins. The results suggest that SauPS-28 could be a lysogenic phage strain. This study thus provides preliminary data to conduct further in-depth analysis of the mechanism of phage-host interaction and provides a reference value for phage therapy.IMPORTANCEIn recent years, drug-resistant bacterial infections have become increasingly serious. As a kind of virus with the ability to infect and lyse drug-resistant bacteria, phage is expected to be a new therapeutic method. In this study, we isolated and purified a new methicillin-resistant Staphylococcus aureus bacteriophage SauPS-28, studied a series of biological characteristics of the bacteriophage, analyzed the genome and structural proteome data of the bacteriophage, and provided reference data for further study of the interaction mechanism between bacteriophage and host bacteria and promoted new antibacterial strategies.

A novel modulation of physiological regulation in cultured Chinese mitten crab (Eriocheir japonica sinensis) in response to consistent salinity changes.

The life history of the Chinese mitten crab (Eriocheir japonica sinensis) includes two migrations: a feeding migration and a reproductive migration. Ambient salinity is one of the most critical factors during migration. In this study, the salinity adaptation mechanism of Chinese mitten crabs was simulated using continuous salinity changes. The expression of six key genes [Na+/K+-ATPase α subunit (NAK-α), V-type H+-ATPase subunit A (VHA-A), Zinc transporter (ZnT), Cl- channel protein 2 (CLCN2), ubiquitin/ribosomal S27 fusionprotein (S27), and glutathione S-transferase (GST)] and the activities of three enzymes [Na+/K+-ATPase (NAK), V-type H+-ATPase (VHA), and glutathione S-transferase (GST)] were evaluated in ten groups exposed to a range of salinity changes during mariculture based on the transcriptome data obtained from short term salinity-induced crabs (ES) compared to control group in freshwater crabs (EF). The results revealed that different genes exhibited different roles in physiological regulation. In total, 3,599 unigenes were significantly and differentially expressed in a comparison between the EF and ES treatments. A novel modulation of gene expression and the corresponding enzyme activity of NAK and VHA exhibited similar patterns. As genes related to osmoregulation, NAK and VHA showed similar patterns of both gene expression and enzyme activity in mariculture. During the gradual change in salinity from 0‰ to 25‰ and back to 0‰, the gene expression and enzyme activities of NAK and VHA initially increased (0‰ â†’ 10‰), weakened (10‰ â†’ 20‰) and then increased again (20‰ â†’ 25‰ â†’ 0‰). S27 could serve as a reference gene in the expression analysis of Chinese mitten crabs under salinity stress. ZnT and CLCN2 were involved in osmoregulation as functional proteins. Our findings provide insights into the regulation mechanisms employed during the migration of the Chinese mitten crab.

Transcriptome Analysis Reveals the Tolerance Mechanism of Mantis Shrimp (Oratosquilla oratoria) under a Lipopolysaccharide Challenge.

Lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria, is considered to lead to some disease development in commercial crustaceans. However, mantis shrimps Oratosquilla oratoria (Crustacea: Stomatopoda) have a strong vitality and ability to resist disease. To study the tolerance mechanism of mantis shrimp, transcriptome analyses were conducted in hepatopancreas of O. oratoria under LPS challenge investigation. Totally, 84 547 044 clean reads were obtained from transcriptomes (43 159 230 in OP (control), 41 387 814 in OL (treatment), respectively). Unigenes, the longest transcript of each gene, with a total length of 68 318 880 bp and the total number of 100 978 were obtained. 8369 (8.28%) of unigenes were successfully annotated in all databases and 54 888 (54.35%) were annotated in at least one database. Finally, 1012 differentially expressed genes (DEGs) including 439 and 573 showed significantly upregulated and downregulated were determined between OL and OP, respectively. Moreover, those DEGs only expressed in OL or OP accounted for 8.99%. The functional classification based on GO and KEGG indicated that the common enrichment categories for the DEGs are "amino sugar metabolic" and "cellular homeostasis" and that the progress of nutrient metabolic and homeostasis in cells is important in facing variable environmental conditions. Protein-protein interaction analysis elucidated proteins, ß-actin (ACTB_G1), T-complex protein subunits (TCPs), heat shock proteins (HSPs), hydroxysteroid dehydrogenase-like protein 2 (HSDL2), kinesin family member 5 (KIF5), methylglutaconyl-CoA hydratase (AUH), and myosin heavy chain (MYH) may play key roles in response to an LPS challenge. This study laid a foundation to further investigate the possible adaptation way that O. oratoria survives in a bacterial challenge.