Venom gland transcriptome from Heloderma horridum horridum by high-throughput sequencing

Cardiac alterations induced by Heloderma horridum horridum venom in rats: An experimental study with ECG analysis using a linear regression algorithm

Envenomation by reptile venom, particularly from lizards, poses significant health risks and can lead to physiological and cardiovascular changes. The venom of Heloderma horridum horridum, endemic to Colima, Mexico, was tested on Wistar rats. Electrocardiographic (ECG) data were collected pre-treatment and at 5-min intervals for 1 h post-envenomation. A specially designed computational linear regression algorithm (LRA) was used for the segmentation analysis of the ECG data to improve the detection of fiducial points (P, Q, R, S, and T) in ECG waves. Additionally, heart tissue was analyzed for macroscopic and microscopic changes. The results revealed significant electrocardiographic alterations, including pacemaker migration, junctional extrasystoles, and intraventricular conduction aberrations. By applying a linear regression algorithm, the study compensated for noise and anomalies in the isoelectric line in an ECG signal, improving the detection of P and T waves and the QRS complex with an efficiency of 97.5%. Cardiac enzyme evaluation indicated no statistically significant differences between the control and experimental groups. Macroscopic and microscopic examination revealed no apparent signs of damage or inflammatory responses in heart tissues. This study enhances our understanding of the cardiovascular impact of Heloderma venom, suggesting a greater influence on changes in conduction and arrhythmias than on direct cardiac damage to the myocardium.

Proteomic Analysis of Heloderma horridum horridum Venom: Assessment to Its Transcriptome and Newfound Proteins

Heloderma horridum horridum, a venomous reptile native to America, has a venom with potential applications in treating type II diabetes. In this work, H. h. horridum venom was extracted, lyophilized, and characterized using enzymatic assays for hyaluronidase, phospholipase, and protease. Proteomic analysis of the venom was conducted employing bottom-up/shotgun approaches, SDS-PAGE, high-pH reversed-phase chromatography, and fractionation of tryptic peptides using nano-LC-MS/MS. The proteins found in H. h. horridum venom were reviewed according to the classification of the transcriptome previously reported. The proteomic approach identified 101 enzymes, 36 other proteins, 15 protein inhibitors, 11 host defense proteins, and 1 toxin, including novel venom components such as calcium-binding proteins, phospholipase A2 inhibitors, serpins, cathepsin, subtilases, carboxypeptidase-like, aminopeptidases, glycoside hydrolases, thioredoxin transferases, acid ceramidase-like, enolase, multicopper oxidases, phosphoglucose isomerase (PGI), fructose-1,6-bisphosphatase class 1, pentraxin-related, peptidylglycine α-hydroxylating monooxygenase/peptidyl-hydroxyglycine α-amidating lyase, carbonic anhydrase, acetylcholinesterase, dipeptidylpeptidase, and lysozymes. These findings contribute to understanding the venomous nature of H. h. horridum and highlight its potential as a source of bioactive compounds. Data are available via PRoteomeXchange with the identifier PXD052417.

Identification of waprin and its microbicidal activity: A novel protein component of honeybee (Apis mellifera) venom

Bee venom is a rich source of biologically and pharmacologically active proteins. Waprin is a protein component of venoms; however, waprin has yet to be identified in bee venom. Moreover, the biological functions of waprin in venoms remain poorly characterized. Thus, in this study, we have identified and characterized waprin: a novel protein component from the venom of honeybees (Apis mellifera). The waprin in A. mellifera venom (Amwaprin) was found to consist of an 80-amino acid mature peptide, in which the whey acidic protein domain contains four conserved disulfide bonds. We discovered the presence of the Amwaprin protein in secreted venom by using an antibody against recombinant Amwaprin produced in baculovirus-infected insect cells. Recombinant Amwaprin exhibited inhibitory activity against microbial serine proteases and elastases but not thrombin or plasmin. It recognized carbohydrates in the microbial cell wall molecules and bound to the live microbial surfaces. The binding action of Amwaprin produced its microbicidal activity by inducing structural damage to bacterial and fungal cell walls. In addition, recombinant Amwaprin is heat-stable and contains no hemolytic activity. These findings demonstrate that Amwaprin acts as a microbicidal and anti-elastolytic agent.

Proteomic analysis of the mandibular glands from the Chinese crocodile lizard, Shinisaurus crocodilurus - Another venomous lizard?

Based on its phylogenetic relationship to monitor lizards (Varanidae), Gila monsters (Heloderma spp.), and the earless monitor Lanthanotus borneesis, the Chinese crocodile lizard, Shinisaurus crocodilurus, has been assigned to the Toxicofera clade, which comprises venomous reptiles. However, no data about composition and biological activities of its oral secretion have been reported. In the present study, a proteomic analysis of the mandibular gland of S. crocodilurus and, for comparison, of the herbivorous Solomon Island skink Corucia zebrata, was performed. Scanning electron microscopy (SEM) of the teeth from S. crocodilurus revealed a sharp ridge on the anterior surface, but no grooves, whereas those of C. zebrata possess a flattened crown with a pointed cusp. Proteomic analysis of their gland extracts provided no evidence of venom-derived peptides or proteins, strongly supporting the non-venomous character of these lizards. Data are available via ProteomeXchange with identifier PXD039424.

SMRT sequencing of the full-length transcriptome of Gekko gecko

Tokay Gecko (Gekko gecko) is a rare and endangered medicinal animal in China. Its dry body has been used as an anti-asthmatic agent for two thousand years. To date, the genome and transcriptome of this species remain poorly understood. Here, we adopted single molecule real-time (SMRT) sequencing to obtain full-length transcriptome data and characterized the transcriptome structure. We identified 882,273 circular consensus (CCS) reads, including 746,317 full-length nonchimeric (FLNC) reads. The transcript cluster analysis revealed 212,964 consensus sequences, including 203,994 high-quality isoforms. In total, 111,372 of 117,888 transcripts were successfully annotated against eight databases (Nr, eggNOG, Swiss-Prot, GO, COG, KOG, Pfam and KEGG). Furthermore, 23,877 alternative splicing events, 169,128 simple sequence repeats (SSRs), 10,437 lncRNAs and 7,932 transcription factors were predicted across all transcripts. To our knowledge, this report is the first to document the G. gecko transcriptome using SMRT sequencing. The full-length transcript data might accelerate transcriptome research and lay the foundation for further research on G. gecko.

Neglected Venomous Animals and Toxins: Underrated Biotechnological Tools in Drug Development

Among the vast repertoire of animal toxins and venoms selected by nature and evolution, mankind opted to devote its scientific attention—during the last century—to a restricted group of animals, leaving a myriad of toxic creatures aside. There are several underlying and justifiable reasons for this, which include dealing with the public health problems caused by envenoming by such animals. However, these studies became saturated and gave rise to a whole group of animals that become neglected regarding their venoms and secretions. This repertoire of unexplored toxins and venoms bears biotechnological potential, including the development of new technologies, therapeutic agents and diagnostic tools and must, therefore, be assessed. In this review, we will approach such topics through an interconnected historical and scientific perspective that will bring up the major discoveries and innovations in toxinology, achieved by researchers from the Butantan Institute and others, and describe some of the major research outcomes from the study of these neglected animals.

The Dragon's Paralysing Spell: Evidence of Sodium and Calcium Ion Channel Binding Neurotoxins in Helodermatid and Varanid Lizard Venoms

Bites from helodermatid lizards can cause pain, paresthesia, paralysis, and tachycardia, as well as other symptoms consistent with neurotoxicity. Furthermore, in vitro studies have shown that Heloderma horridum venom inhibits ion flux and blocks the electrical stimulation of skeletal muscles. Helodermatids have long been considered the only venomous lizards, but a large body of robust evidence has demonstrated venom to be a basal trait of Anguimorpha. This clade includes varanid lizards, whose bites have been reported to cause anticoagulation, pain, and occasionally paralysis and tachycardia. Despite the evolutionary novelty of these lizard venoms, their neuromuscular targets have yet to be identified, even for the iconic helodermatid lizards. Therefore, to fill this knowledge gap, the venoms of three Heloderma species (H. exasperatum, H. horridum and H. suspectum) and two Varanus species (V. salvadorii and V. varius) were investigated using Gallus gallus chick biventer cervicis nerve–muscle preparations and biolayer interferometry assays for binding to mammalian ion channels. Incubation with Heloderma venoms caused the reduction in nerve-mediated muscle twitches post initial response of avian skeletal muscle tissue preparation assays suggesting voltage-gated sodium (Na_V) channel binding. Congruent with the flaccid paralysis inducing blockage of electrical stimulation in the skeletal muscle preparations, the biolayer interferometry tests with Heloderma suspectum venom revealed binding to the S3–S4 loop within voltage-sensing domain IV of the skeletal muscle channel subtype, Na_V1.4. Consistent with tachycardia reported in clinical cases, the venom also bound to voltage-sensing domain IV of the cardiac smooth muscle calcium channel, Ca_V1.2. While Varanus varius venom did not have discernable effects in the avian tissue preparation assay at the concentration tested, in the biointerferometry assay both V. varius and V. salvadorii bound to voltage-sensing domain IV of both Na_V1.4 and Ca_V1.2, similar to H. suspectum venom. The ability of varanid venoms to bind to mammalian ion channels but not to the avian tissue preparation suggests prey-selective actions, as did the differential potency within the Heloderma venoms for avian versus mammalian pathophysiological targets. This study thus presents the detailed characterization of Heloderma venom ion channel neurotoxicity and offers the first evidence of varanid lizard venom neurotoxicity. In addition, the data not only provide information useful to understanding the clinical effects produced by envenomations, but also reveal their utility as physiological probes, and underscore the potential utility of neglected venomous lineages in the drug design and development pipeline.

Utilisation of compounds from venoms in drug discovery

Difficult drug targets are becoming the normal course of business in drug discovery, sometimes due to large interacting surfaces or only small differences in selectivity regions. For these, a different approach is merited: compounds lying somewhere between the small molecule and the large antibody in terms of many properties including stability, biodistribution and pharmacokinetics. Venoms have evolved over millions of years to be complex mixtures of stable molecules derived from other somatic molecules, the stability comes from the pressure to be ready for delivery at a moment's notice. Snakes, spiders, scorpions, jellyfish, wasps, fish and even mammals have evolved independent venom systems with complex mixtures in their chemical arsenal. These venom-derived molecules have been proven to be useful tools, such as for the development of antihypotensive angiotensin converting enzyme (ACE) inhibitors and have also made successful drugs such as Byetta® (Exenatide), Integrilin® (Eptifibatide) and Echistatin. Only a small percentage of the available chemical space from venoms has been investigated so far and this is growing. In a new era of biological therapeutics, venom peptides present opportunities for larger target engagement surface with greater stability than antibodies or human peptides. There are challenges for oral absorption and target engagement, but there are venom structures that overcome these and thus provide substrate for engineering novel molecules that combine all desired properties. Venom researchers are characterising new venoms, species, and functions all the time, these provide great substrate for solving the challenges presented by today's difficult targets.