In the past, toxinological research on reptiles has focused principally on clinically important species. As a result, our understanding of the evolution of the reptile venom system is limited. Here, for the first time, we describe the structural and molecular evolutionary features of the mandibular toxin-secreting gland of Abronia graminea, a representative of one of the poorly known and entirely arboreal lineages of anguimorph lizards. We show that the mandibular gland is robust and serous, characters consistent with those expected of a toxin-secreting gland in active use. A wide array of transcripts were recovered that were homologous to those encoded by the indisputably venomous helodermatid lizards. We show that some of these toxin transcripts are evolving under active selection and show evidence of rapid diversification. Helokinestatin peptides in particular are revealed to have accumulated residues that have undergone episodic diversifying selections. Conversely, the natriuretic peptides have evolved under tremendous evolutionary constraints despite being encoded in tandem with helokinestatins by the same gene precursor. Of particular note is the sequencing for the first time of kunitz peptides from a lizard toxin-secreting gland. Not only are kunitz peptides shown to be an ancestral toxicoferan toxin, the ancestral state of this peptide is revealed to be a dual domain encoding precursor. This research provides insight into the evolutionary history of the ancient toxicoferan reptile venom system. In addition, it shows that even 'clinically irrelevant' species can be a rich source of novel venom components, worthy of investigation for drug design and biomedical research.
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http://dx.doi.org/10.1007/s00239-012-9529-9 | DOI Listing |
Gene
January 2023
Grupo de Investigación de Biología y Ecología de Artrópodos. Facultad de Ciencias. Universidad del Tolima, Colombia. Electronic address:
Current available information on reptile genomes provides great potential for the study of unique adaptations from a genomic perspective. We compared differences in base composition and codon usage patterns across 400 reptile mitochondrial genomes assessing AT and GC skew, GC frequency, codon usage, effective number of codons, and codon adaptation index. We identified poor GC content in reptile mitochondrial genomes, with a predominant bias toward Adenine.
View Article and Find Full Text PDFHistochem Cell Biol
September 2020
UCIBIO-Applied Molecular Biosciences Unit, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
Either through differentiated glands or specialised individual cells, the coating epithelia of soft-bodied marine invertebrates are responsible for the secretion of a broad span of peptidic substances, from protective mucins to biocides. These secretions are characterised by the presence of cysteine-rich proteins and peptides, rendering a distinct histochemical signature of secretory epithelia. Through a histochemical procedure for fluorescence microscopy in paraffin sections, we performed a comparative assessment of the distribution of thiol-rich compounds in multiple epithelia of different species of intertidal Polychaeta, which revealed distinctive patterns of distribution that closely relate to ecology, morphoanatomy and physiology.
View Article and Find Full Text PDFToxicon
September 2019
Diretoria de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias (FUNED), Belo Horizonte, MG, Brazil. Electronic address:
In the last decades, main advances were achieved in the identification, structural and pharmacological characterization of Phoneutria nigriventer toxins. However, studies on the venom-producing apparatus are rare. Presently, we applied immunolabeling to historesin-embedded cross-sections of P.
View Article and Find Full Text PDFJ Mol Evol
December 2012
Venom Evolution Laboratory, School of Biological Sciences, University of Queensland, St. Lucia, QLD, 4072, Australia.
In the past, toxinological research on reptiles has focused principally on clinically important species. As a result, our understanding of the evolution of the reptile venom system is limited. Here, for the first time, we describe the structural and molecular evolutionary features of the mandibular toxin-secreting gland of Abronia graminea, a representative of one of the poorly known and entirely arboreal lineages of anguimorph lizards.
View Article and Find Full Text PDFToxicon
April 2010
Laboratório Especial de Toxinologia Aplicada (CAT/CEPID), Instituto Butantan, Av. Vital Brasil 1500, São Paulo, 05503-900, Brazil.
The paraphyletic family Colubridae comprises several species of rear-fanged snakes with toxin-secreting Duvernoy's gland, some of them able to cause human envenomation with systemic and/or local damage. In this work we have explored some aspects of biochemical composition and activity of the venoms of five species from Colubridae family from Brazil. Taken together our results suggest distinct features in colubrid venoms, which could be related to the presence of still unknown toxins.
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