Harmful algal blooms (HABs) produce potent neurotoxins, such as domoic acid (DA) and saxitoxin (STX), which negatively impact marine mammal health. To contextualize these threats within specific regional ecosystems, we conducted a comprehensive meta-analysis of algal toxin concentrations in stranded and non-stranded seals and sea lions reported between 1990 and 2025. Following a systematic screening of 2377 records, 15 studies met the criteria for inclusion in our systematic review and quantitative analysis. Both toxins displayed substantial variability among studies. Notably, the concentrations of DA found in feces were markedly higher than in other matrices, and feces appears to be a high-yield matrix for detecting recent exposure. Urine and serum showed moderate DA levels, while fetal fluids were among the lowest. Geographically, most studies originated from California and the Alaskan Arctic. Multi-matrix monitoring of algal toxins is required in remote or logistically challenging regions. We propose that exposure to algal and cyanobacterial neurotoxins is a testable contributor to recurrent, unexplained mass mortality events among Caspian seals (Pusa caspica) and that targeted toxicological screening within the Caspian Sea ecosystem is urgently needed.
Pseudomonas plecoglossicida is a Gram-negative opportunistic pathogen in aquaculture that infects several economically important fish species, including large yellow croaker, orange-spotted grouper and yellow drum. Due to its high incidence and mortality rates, visceral white spot disease (VWND) caused by P. plecoglossicida has become a major bacterial disease threatening the sustainable development of aquaculture and has caused huge economic losses worldwide. Owing to tremendous technological advances, such as dual RNA-seq, our understanding of P. plecoglossicida pathogenesis and associated host defense mechanisms has been greatly enhanced. Nevertheless, many pathogenecity-related mechanisms of P. plecoglossicida remain uncovered, including the functions of various unannotated bacterial virulence factors. Therefore, there is an urgent need to develop new theoretical and practical approaches to address the challenges of P. plecoglossicida. In this review, we summarize the current research advances in the virulence factors, prevention and control strategies, and host–pathogen interactions of this microbial pathogen. This review will contribute to a more comprehensive understanding of the pathogenesis of P. plecoglossicida and provide new insights and strategies for its prevention and control.
Highly lethal Vibrio disease (HLVD) is a newly emerging shrimp disease caused by VTc toxin-producing Vibrio strains, designated VHLVD. VTc toxin, composed of VTcA, VTcB, and VTcC subunits, is a novel member of the Tc toxin family. Structural and functional studies of VTc toxin have been hindered by the lack of efficient purification protocols. Here, we established a simple method for purification of milligram-scale bioactive VTc toxin via anion-exchange chromatography. The procedures of cell lysis, sample pretreatment, and anion-exchange chromatography were optimized. This protocol yielded approximately 1.5 mg of high-purity toxin from 40 mL of bacterial culture (VHLVD strain vp-HL-202005). The composition of the product was confirmed by SDS-PAGE and LC-MS/MS. Purified VTc toxin was bioactive, inducing typical HLVD mortality in shrimp post-larvae. Transmission Electron Microscopy (TEM) and native PAGE analysis revealed two distinct structural populations, which may represent the club-shaped holotoxin (VTcA2-VTcB2-VTcC2) and the bell-shaped VTcA2 homopentamer. This simple and efficient method will greatly facilitate research on the fine structure and functional mechanism of VTc toxin and thus expand our knowledge of the Tc toxin family.
Regulatory approval may occur before or after a research topic becomes prominent in the scientific literature. We examined this temporal relationship using botulinum neurotoxin (BoNT) as a longitudinal case study. We analyzed 2065 anatomy-related BoNT publications indexed in Web of Science and Scopus from 1983 to 2024. The literature was divided into 16 periods based on U.S. FDA approval dates for onabotulinumtoxinA, and indication-related keyword rankings and thematic clusters were compared with the corresponding approval dates. Among the 10 indication groups examined, 7 showed prominent indication-related keywords before FDA approval, 2 showed signals around the time of approval, and 1 showed a post-approval signal. We describe these patterns as “proactive exploration” when scientific attention became prominent before approval and “reactive catalysis” when it became more prominent around or after approval. Differences in the observed lag may be related to target anatomical complexity and market orientation, but this remains conceptual. Overall, the findings show that time-resolved scientometrics can retrospectively identify scientific patterns associated with regulatory milestones. The approach is hypothesis-generating and requires prospective validation before it can be used for regulatory forecasting.
Debate over the origin of squamate venom is frequently distorted by treating molecular availability, toxin recruitment and secretion, functional venom, and delivery-system elaboration as a single evolutionary event. This review separates these transitions and reassesses early venom evolution in anguimorph lizards and snakes using anatomical, molecular, proteomic, functional, ecological, and phylogenetic evidence. The species-level ancestral-state reconstructions of a recent Wüster, Modahl, and Arbuckle manuscript are internally robust to the four coding schemes tested and accommodate uncertain tips and reversible venom loss. Their inference nevertheless remains conditional on a binary definition of observed functional venom, a single hidden precursor category, a homogeneous transition process, and non-caenophidian snake states that were not varied in the relevant sensitivity analyses. While they coded two origins of venom within Anguimorpha, gland anatomy and derived oral products make an early functional origin followed by retention, reduction, loss, and parallel elaboration a strongly supported alternate hypothesis. However, as critical bridge taxa lack direct evidence of natural delivery, realistic dose, or secretion-specific fitness benefit, resolution of the history remains unresolved. For Heloderma, field studies of H. suspectum and H. horridum, together with painful, prolonged defensive bites, support a defensive role, although its primacy (to the exclusion of an additional predatory function) as advocated by them is sensitive to observational bias. Neurotoxic, cardiovascular, and coagulotoxic activities make a predatory contribution supported, leaving the original selective driver unresolved. Within Serpentes, their placement of venom at the base of the Caenophidia is challenged by distributed maxillary, mandibular, and rictal glands and derived oral products in non-caenophidian taxa, making an origin before Caenophidia a viable alternative hypothesis. Derived mucous systems in boas and pythons and specialised Scolecophidia cannot alone polarise the ancestral snake state. Current evidence is therefore insufficient to distinguish one shared functional origin from two functionalisations of a homologous ancestral oral secretory system. No alternative comparative reconstruction is performed; the review shows only that earlier origins remain viable and categorical absence coding is insufficiently secure for several poorly investigated taxa. Resolution requires matched gland cell biology, orthology- and synteny-resolved genomics, quantitative secretion proteomics, realistic functional assays, secretion-specific ecological tests, broader Iguania and non-caenophidian snake sampling, and ancestral-state models that represent graded evidence, both false-negative and false-positive classification, reduction, loss, and phylogenetic uncertainty.
