Po-Cheng Chen

Vibrio alginolyticus is a major aquaculture pathogen whose virulence is largely mediated by the type II secretion system (T2SS). However, the functions of key T2SS components, including gspJ, gspL, and gspM, remain unclear. Earlier research indicated that a Scutellaria baicalensis extract at 8 mg/mL markedly suppressed the growth, motility, and biofilm-forming capacity of V. alginolyticus ND-01 (OD₆₀₀ = 0.5) following 12 h of treatment, with the resulting stress substantially altering the expression of multiple genes, including gspJ, gspL, and gspM. The gspJ-RNAi, gspL-RNAi, and gspM-RNAi strains were constructed using RNAi. Biological functional assays demonstrated that stable silencing of gspJ, gspL, and gspM markedly decreased biofilm formation ability (84.01%, 24.99%, and 78.26%, respectively) and host cell adhesion (73.57%, 75.65%, and 79.61%, respectively); gspJ and gspM silencing reduced motility (54.82% and 57.42%, respectively), whereas gspL silencing enhanced motility by 38.49%, indicating their essential roles in virulence-associated phenotypes. Notably, in vivo infection of Epinephelus coioides revealed that gspL-RNAi significantly attenuated pathogenicity, as evidenced by reduced host mortality (50%) and decreased bacterial colonization in liver and spleen tissues, compared with the wild-type group. Consistently, Label-Free Proteomic Analysis of the gspL-RNAi strain identified 189 differentially expressed proteins in the gspL-silenced strain, with enrichment in two-component signaling, ABC transport systems, and amino acid metabolism. Network analysis further positioned gspL as a central regulatory hub linking T2SS activity to signal transduction, transport, and metabolic pathways. In addition, the expression of gspJ-RNAi, gspL-RNAi, and gspM-RNAi exhibited distinct responses to environmental stresses, including pH and temperature variation. Collectively, our findings highlight that gspJ, gspL, and gspM are critical regulators of virulence in V. alginolyticus, with gspL playing a central role in coordinating T2SS function with global regulatory networks. This study advances our understanding of the pathogenic mechanisms of V. alginolyticus and provides potential targets for the development of anti-virulence aquaculture strategies.

The aquatic pathogen Aeromonas salmonicida SRW-OG1 is responsible for substantial mortality in Epinephelus coioides and many other cultured fish species. This study investigates the contribution of trpE to the pathogenicity of A. salmonicida SRW-OG1 in E. coioides. Specifically, trpE encodes a key enzyme in tryptophan biosynthesis; however, its function in regulating virulence in A. salmonicida remains uncertain. Phenotypic assays indicate that deletion of trpE markedly impaired bacterial growth and significantly reduced multiple virulence-associated traits, including swimming motility, biofilm formation, chemotaxis, hemolytic activity, and extracellular enzyme activity. Transmission electron microscopy revealed that the ΔtrpE mutant lacked flagella, indicating that trpE is involved in flagellar formation or maintenance. In an E. coioides infection model, fish infected with ΔtrpE showed a cumulative survival rate of 48.3%, whereas those infected with the wild-type SRW-OG1 suffered 100% mortality. The ΔtrpE mutant also exhibited reduced bacterial loads in target organs (liver, head kidney, and spleen), while pretreatment with ΔtrpE provided 53.3% protection against a subsequent wild-type challenge. Transcriptomic analysis identified 616 differentially expressed genes, mainly enriched in pathways including flagellar assembly, bacterial chemotaxis, two-component systems, quorum sensing, and biofilm formation. Metabolomic analysis further showed a significant decrease in N-butyryl-L-homoserine lactone, an acyl-homoserine lactone quorum-sensing signal in the ΔtrpE mutant. These findings suggest that trpE contributes to mesophilic A. salmonicida SRW-OG1’s virulence by partially affecting quorum-sensing signal production and motility-related pathways. The attenuated phenotype and protective effect of ΔtrpE indicate its potential as a live attenuated vaccine candidate for controlling A. salmonicida infection in aquaculture.

Sustainable management of Portunus pelagicus is hindered by uncertain stock boundaries across rapidly changing marginal seas and culturally diverse markets. We measured 12 size-adjusted morphometrics in 525 adults from five sites (Kyushu, Xiamen, Tainan, Hong Kong, and Singapore). Canonical variate analysis resolved three robust groups that mirror oceanographic regimes: a Kuroshio–China group (Kyushu, Xiamen, and Hong Kong), a Taiwan Strait subgroup (Tainan), and a Southeast Asia group (Singapore). Permutation tests (1000 runs) showed near-zero probabilities of observing the low misclassification rates by chance (p < 0.001). A reproductive trait (female AB3W) displayed group-specific allometric slopes, consistent with local functional demands. We integrate these results with a cultural ecology lens—linking ornamental carapace valuation to selective harvest—to propose morphological management units (MMUs) and region-specific rules that can be implemented immediately and refined with genomics. This work reframes a descriptive morphometric study into a socio-ecological mechanism for climate-ready, actionable fisheries governance.

Blue swimmer crabs (Portunus pelagicus) primarily inhabit the coastal regions of Southeast Asia. This study aimed to examine their population genetic structure, phylogeography, and historical demography by applying partial sequences to the control region in the mitochondrial DNA. The analysis focused on 6 populations comprising 166 individual samples collected from Taiwan (Kezailiao Kaohsiung (KK) and Penghu (PH)), mainland China (Xiamen (XM) and Hong Kong (HK)), Vietnam (Hanoi (VN)), and Singapore (SGP). The estimated nucleotide diversity (π) for all of the samples was 0.062, with values ranging between 0.018 (PH) and 0.045 (HK). Our study collected 116 haplotypes and classified them into lineages A and B. The XM, HK, VN, and SGP populations made up lineage A, and the PH and KK populations comprised lineage B. For each lineage, the results highlighted indications of demographic expansion. Lineage A can be traced back to the second-to-last interglacial period, while lineage B possibly originated in the last glacial period. There were significant differences in the F_ST values among the six populations, except for the pairs HK–XM and PH–KK. In conclusion, the phylogeography and genetic structure of P. pelagicus in Southeast Asia were potentially affected by the Pleistocene glacial cycles and human introduction. These findings further highlight the possible dispersal routes of P. pelagicus throughout Southeast Asia.

The three-spot swimming crab (Portunus sanguinolentus) is mainly distributed in South East Asia. An analysis of mitochondrial control region partial sequences allows us to determine the population genetic structure, phylogeography and historical demography of this species in East Asia. The seven populations, which included 110 individuals, were collected from mainland China (Shanghai, SH, Xiamen, XM and Hong Kong, HK), Taiwan (Yilan, YL, Taichung, TC, Donggang, DG) and Singapore (Singapore, SGP). The nucleotide diversity (π) of all individuals was 0.01149, with values ranging from 0.00372 (SGP) to 0.01345 (YL). In total, 90 haplotypes have been identified, which can be divided into two major lineages: lineage A consists of specimens from SH, YL, XM, TC and DG, and lineage B corresponds to specimen from SGP. From the second to the most recent interglacial period, population expansion was observed in each lineage. However, a low level of genetic differentiation was also observed in the three-spotted swimming crab, P. sanguinolentus, according to F_ST values. Our results suggest that several past and present habitat configurations have shaped the genetic patterns of P. sanguinolentus until now. During Pleistocene glaciations, when sea levels were low, this species may have moved along the coast from Southeast Asia to China. It first colonized the Hong Kong area during this era. After sea levels rose and shorelines receded, it subsequently spread to the coast of mainland China.

The use of the flexible ureteroscope for treating renal and ureteral calculi has rapidly increased in the last decade. Although the use of the flexible ureteroscope by experienced surgeons has excellent outcomes and safety profiles, several studies have reported many surgical complications with its use. We conducted a narrative review of the published literature sourced from PubMed. We used a combination of three keywords: “ureteroscope,” “morbidity,” and “urolithiasis,” with or without the additional keywords of “infection,” “mortality,” “hematoma,” and “ureteral injury.” Infection, bleeding, and ureteral injury are the main complications. We analyzed the possible causes of morbidity and death after the use of a flexible ureteroscope. Finally, we propose recommendations to prevent these complications.

Construction contractor evaluation is a critical issue in successfully completing a project. It is important for project owners and other stakeholders to identify potentially failing contractors and to avoid awarding them contracts. Previous studies developed construction contractor default prediction models incorporating managerial or economic variables into traditional financial ratio models to enhance predicting power. However, managerial variables are subjective and qualitative, and both economic variables and financial ratios are only available periodically and may not provide the necessary information in time. This study predicts contractor default by employing three option-based credit models (BSM, CB, and BS) based on stock market information, and the empirical results show that all of the models have strong discriminatory power in ranking contractors from riskiest to safest. The misclassification rates of the three models are BSM: 10%, CB: 10%, and BS: 12.7%, all of which are smaller than that of...