The earless monitor lizard Lanthanotus borneensis – A venomous animal?

Mebs, Dietrich; Lomonte, Bruno; Fernández, Julián; Calvete, Juan J.; Sanz, Líbia; Mahlow, Kristin; Müller, Johannes; Köhler, Günther; Zollweg, Michael

doi:10.1016/j.toxicon.2020.11.013

Cited by 6 publications

(5 citation statements)

References 22 publications

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“…The basal varanoid lizard Lanthanotus borneensis has previously been shown to possess an enlarged mandibular venom gland homologous to that of the sister genus Varanus , and to possess a venom rich in kallikrein enzymes [ 5 , 132 ]. Consistent with this, the venom has previously been shown to be fibrinogenolytic.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this, the venom has previously been shown to be fibrinogenolytic. Regardless, a recent study rejected the classification of L. borneensis as venomous [ 132 ], with the authors stating kinin-releasing kallikrein activity needed to be present for L. borneensis to be considered as venomous, justifying this through the citation of their previous work characterising kininogen cleavage by Heloderma venoms [ 15 ]. Thus, the homology with Heloderma and Varanus of gland morphology, fibrinogenolytic activity, and kininogenolytic activity certainly supports the inclusion of L. borneensis as a venomous member of the Anguimorpha clade within the Toxicofera.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, serious bites from V. griseus and V. komodoensis displayed symptoms similar to Heloderma envenomations and consistent with bradykinin release [ 33 , 34 , 35 ]. However despite the abundance of homologous kallikrein enzymes within varanid lizard and L. borneensis venoms [ 4 , 5 , 6 , 11 , 132 ] the bradykinin liberating activity of these venoms has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

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The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms

Dobson,

Chowdhury,

Tai-A-Pin

et al. 2024

Toxins

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Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards have long been assumed to be for defensive purposes, there is increasing evidence of toxic activities more useful for predation than defence (such as paralytic neurotoxicity). This study aimed to ascertain the effects of Heloderma, Lanthanotus, and Varanus lizard venoms on the coagulation and cardiovascular systems. Anticoagulant toxicity was demonstrated for the Varanus species studied, with the venoms prolonging clotting times in human and bird plasma due to the destructive cleavage of fibrinogen. In contrast, thromboelastographic analyses on human and bird plasmas in this study demonstrated a procoagulant bioactivity for Heloderma venoms. A previous study on Heloderma venom using factor-depleted plasmas as a proxy model suggested a procoagulant factor was present that activated either Factor XI or Factor XII, but could not ascertain the precise target. Our activation studies using purified zymogens confirmed FXII activation. Comparisons of neonate and adult H. exasperatum, revealed the neonates to be more potent in the ability to activate FXII, being more similar to the venom of the smaller species H. suspectum than the adult H. exasperatum. This suggests potent FXII activation a basal trait in the genus, present in the small bodied last common ancestor. This also indicates an ontogenetic difference in prey preferences in the larger Heloderma species paralleing the change in venom biochemistry. In addition, as birds lack Factor XII, the ability to clot avian plasma suggested an additional procoagulant site of action, which was revealed to be the activation of Factor VII, with H. horridum being the most potent. This study also examined the effects upon the cardiovascular system, including the liberation of kinins from kininogen, which contributes to hypotension induction. This form of toxicity was previously described for Heloderma venoms, and was revealed in this study was to also be a pathophysiological effect of Lanthanotus and Varanus venoms. This suggests that this toxic activity was present in the venom of the last common ancestor of the anguimorph lizards, which is consistent with kallikrein enzymes being a shared toxin trait. This study therefore uncovered novel actions of anguimorph lizard venoms, not only contributing to the evolutionary biology body of knowledge but also revealing novel activities to mine for drug design lead compounds.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms

Dobson,

Chowdhury,

Tai-A-Pin

et al. 2024

Toxins

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“…A recent study examining the abilities of lizard salivary secretions to induce coagulopathies on the human blood convincingly demonstrated that, unlike Heloderma and varanid lizards, skink saliva does not show any effect [16]. Furthermore, given the lack of strong evidence confirming the presence of venom, some reports have even argued for the absence of venom in certain lizards within the "Toxicofera" clade [17]. These findings collectively point to the lack of a venom arsenal in Scincidae.…”

Section: Evidence Supports the Lack Of Venom In Scincidaementioning

confidence: 99%

The Curious Case of the “Neurotoxic Skink”: Scientific Literature Points to the Absence of Venom in Scincidae

Sunagar

Abraham

2021

Toxins

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In contrast to the clearly documented evolution of venom in many animal lineages, the origin of reptilian venom is highly debated. Historically, venom has been theorised to have evolved independently in snakes and lizards. However, some of the recent works have argued for the common origin of venom in “Toxicofera” reptiles, which include the order Serpentes (all snakes), and Anguimorpha and Iguania lizards. Nevertheless, in both these contrasting hypotheses, the lizards of the family Scincidae are considered to be harmless and devoid of toxic venoms. Interestingly, an unusual clinical case claiming neurotoxic envenoming by a scincid lizard was recently reported in Southern India. Considering its potentially significant medicolegal, conservation and evolutionary implications, we have summarised the scientific evidence that questions the validity of this clinical report. We argue that the symptoms documented in the patient are likely to have resulted from krait envenomation, which is far too frequent in these regions.

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“…As the sole living representative of the family Lanthanotidae and an endemic of the island, much interest exists on its biology and conservation. Poorly-known for the first century of its description, this species resurfaced in the pet trade within the last decade, at which time, sporadic information on its biology and trade started to emerge (Janssen, 2018;Das and Auliya, 2021;Mebs et al, 2021). Furthermore, although the lineage has been shown to be sister to the clade comprising the essentially diurnal varanids (Branch, 1982;Ast, 2001), L. borneensis is unique in being strictly nocturnal.…”

Section: Introductionmentioning

confidence: 99%

Thermal biology of Lanthanotus borneensis (Lanthanotidae) in Sarawak, Borneo

Leah,

Min,

Das

2023

Amphib.-Reptilia

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Lanthanotus borneensis, the Bornean earless monitor, is a monotypic member of the family Lanthanotidae, and restricted to the island of Borneo. Little has been published on its field ecology. This study investigated aspects of its thermal biology through an analysis of surface body temperatures of free ranging individuals against corresponding environmental temperatures, in order to explore aspects of microhabitat utilisation in relation to thermoregulation. A generalised linear mixed model shows significant effect of air and substrate temperatures, but not of water temperature. Further, the fixed effects of substrate temperature (coefficient estimate 0.396; ) versus ambient temperature (0.264; ), is suggestive of thigmothermy as the primary mode of thermoregulation. The species does not appear to utilise specific microhabitat structures to thermoregulate, the results of these observations suggesting that it is a thermoconformer.

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The earless monitor lizard Lanthanotus borneensis – A venomous animal?

Cited by 6 publications

References 22 publications

The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms

The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms

The Curious Case of the “Neurotoxic Skink”: Scientific Literature Points to the Absence of Venom in Scincidae

Thermal biology of Lanthanotus borneensis (Lanthanotidae) in Sarawak, Borneo

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