Characterization of a Specialized Venomous Spine System and Identification of a Cytolytic Toxin, Cytolytic Toxin-Alpha-like (CTα-L/BGT-1), in the Bagrid Catfish Leiocassis longirostris
- 1Fisheries Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu 611731, China
- 2Key Laboratory of Aquatic Health and Intelligent Aquaculture of Sichuan Province, Chengdu 611731, China
- 3Department of Aquatic Animal Medicine, College of Aquaculture, Sichuan Agricultural University, Chengdu 611130, China
Abstract
Venomous spines are widespread defensive structures in fishes, yet the anatomical organization, molecular composition, and cellular basis of venom systems in many catfishes remain poorly characterized. Here, we combined morphology, proteomics, FISH, scRNA-seq, sequence comparison, and in vivo puncture to study L. longirostris spines. Histology revealed a spine architecture with longitudinal grooves, epidermal glands, a basement layer, and internal canals. DIA-MS identified a spine-enriched toxin repertoire in which CTα-L accounted for 95.34% of toxin abundance and was among the top proteins. Based on its sequence characteristics and close relationship to CTα-L homologs from bagrid catfishes, we designated this protein Bagridae toxin-1 (BGT-1). Spatial and single-cell analyses localized CTα-L-family transcripts to glandular and basement-layer compartments, with enrichment in several specialized cellular populations, including proliferating endothelial cells, immature epithelial progenitor cells, and junctional vascular smooth muscle cells. Sequence and structural comparisons revealed that BGT-1 retains conserved features of fish cytolytic toxins while exhibiting a distinctive multidomain architecture containing SNTX-like, Stonustoxin-associated, thioredoxin-like, FNIII, and tandem galectin domains. Structural modeling further identified a predicted pore-compatible architecture within the conserved toxin-associated core and provided a basis for a putative working model of BGT-1-mediated cytolysis. Finally, puncture with active spines caused rapid hemorrhage, edema, myofiber injury, inflammatory infiltration, and increased TUNEL-positive cells in vivo, whereas heat-inactivated spines produced substantially milder tissue damage. Together, these findings link specialized anatomy, a predominant toxin-associated protein, its cellular localization, molecular architecture, and in vivo activity in this venom system, providing a framework for comparative venom studies across catfishes.
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BibTeX
@article{feng2026characterization,
title = {{Characterization of a Specialized Venomous Spine System and Identification of a Cytolytic Toxin, Cytolytic Toxin-Alpha-like (CTα-L/BGT-1), in the Bagrid Catfish Leiocassis longirostris}},
author = {Yang Feng and Shuai Liu and Senyue Liu and Jian Zhou and Chengyan Mou and Han Zhao and Huadong Li and Qiang Li and Yongqiang Deng},
journal = {Biomolecules},
year = {2026},
month = nov,
doi = {10.3390/biom16111587},
url = {https://www.mdpi.com/2218-273X/16/11/1587},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Characterization of a Specialized Venomous Spine System and Identification of a Cytolytic Toxin, Cytolytic Toxin-Alpha-like (CTα-L/BGT-1), in the Bagrid Catfish Leiocassis longirostris
AU - Yang Feng
AU - Shuai Liu
AU - Senyue Liu
AU - Jian Zhou
AU - Chengyan Mou
AU - Han Zhao
AU - Huadong Li
AU - Qiang Li
AU - Yongqiang Deng
PY - 2026
DA - 2026/11/01
JO - Biomolecules
DO - 10.3390/biom16111587
UR - https://www.mdpi.com/2218-273X/16/11/1587
AB - Venomous spines are widespread defensive structures in fishes, yet the anatomical organization, molecular composition, and cellular basis of venom systems in many catfishes remain poorly characterized. Here, we combined morphology, proteomics, FISH, scRNA-seq, sequence comparison, and in vivo puncture to study L. longirostris spines. Histology revealed a spine architecture with longitudinal grooves, epidermal glands, a basement layer, and internal canals. DIA-MS identified a spine-enriched toxin repertoire in which CTα-L accounted for 95.34% of toxin abundance and was among the top proteins. Based on its sequence characteristics and close relationship to CTα-L homologs from bagrid catfishes, we designated this protein Bagridae toxin-1 (BGT-1). Spatial and single-cell analyses localized CTα-L-family transcripts to glandular and basement-layer compartments, with enrichment in several specialized cellular populations, including proliferating endothelial cells, immature epithelial progenitor cells, and junctional vascular smooth muscle cells. Sequence and structural comparisons revealed that BGT-1 retains conserved features of fish cytolytic toxins while exhibiting a distinctive multidomain architecture containing SNTX-like, Stonustoxin-associated, thioredoxin-like, FNIII, and tandem galectin domains. Structural modeling further identified a predicted pore-compatible architecture within the conserved toxin-associated core and provided a basis for a putative working model of BGT-1-mediated cytolysis. Finally, puncture with active spines caused rapid hemorrhage, edema, myofiber injury, inflammatory infiltration, and increased TUNEL-positive cells in vivo, whereas heat-inactivated spines produced substantially milder tissue damage. Together, these findings link specialized anatomy, a predominant toxin-associated protein, its cellular localization, molecular architecture, and in vivo activity in this venom system, providing a framework for comparative venom studies across catfishes.
SN - 2218-273X
ER -