Kartik Sunagar

Kartik Sunagar
Indian Institute of Science | IISC · Centre for Ecological Sciences

BSc, MSc, PhD

About

69
Publications
34,327
Reads
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3,102
Citations
Introduction
I am an evolutionary biologist with a passion for venom research. My research focuses on unraveling the forces of natural selection that sculpt toxin molecular scaffolds in the animal kingdom.
Additional affiliations
August 2017 - present
Indian Institute of Science
Position
  • Professor
January 2017 - present
Indian Institute of Science
Position
  • Professor (Assistant)
Description
  • I have been teaching a graduate and undergraduate-level course on Evolutionary Biology with an emphasis on molecular and genome evolution.
May 2015 - August 2017
Hebrew University of Jerusalem
Position
  • Fellow

Publications

Publications (69)
Article
Full-text available
Animal venoms are theorized to evolve under the significant influence of positive Darwinian selection in a chemical arms race scenario, where the evolution of venom resistance in prey and the invention of potent venom in the secreting animal exert reciprocal selection pressures. Venom research to date has mainly focused on evolutionarily younger li...
Article
Full-text available
The question about whether evolution is unpredictable and stochas-tic or intermittently constrained along predictable pathways is the subject of a fundamental debate in biology, in which understanding convergent evolution plays a central role. At the molecular level, documented examples of convergence are rare and limited to occurring within specif...
Article
Full-text available
Despite Cnidaria (sea anemones, corals, jellyfish and hydroids) being the oldest venomous animal lineage, structure-function relationships, phyletic distributions and the molecular evolutionary regimes of toxins encoded by these intriguing animals are poorly understood. Hence, we have comprehensively elucidated the phylogenetic and molecular evolut...
Article
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Cysteine-rich secretory proteins (CRISPs) are glycoproteins found exclusively in vertebrates and have broad diversified functions. They are hypothesized to play important roles in mammalian reproduction and in reptilian venom, where they disrupt homeostasis of the prey through several mechanisms, including among others, blockage of cyclic nucleotid...
Chapter
Snakes comprise nearly 4,000 extant species found on all major continents except Antarctica. Morphologically and ecologically diverse, they include burrowing, arboreal, and marine forms, feeding on prey ranging from insects to large mammals. Snakes are strikingly different from their closest lizard relatives, and their origins and early diversifica...
Article
Full-text available
Snake envenoming afflicts the Indian subcontinent with the highest rates of mortality (47,000) and morbidity globally. The only effective treatment for snakebites is the administration of antivenom, which is produced by the hyperimmunisation of equines. Commercial Indian antivenoms, however, have been shown to exhibit a poor preclinical performance...
Article
Full-text available
The Andaman and Nicobar Islands are an abode to a diversity of flora and fauna, including the many endemic species of snakes, such as the elusive Andaman cobra ( Naja sagittifera ). However, the ecology and evolution of venomous snakes inhabiting these islands have remained entirely uninvestigated. This study aims to bridge this knowledge gap by in...
Article
Full-text available
Snakebite envenoming is a neglected tropical disease that may claim over 100,000 human lives annually worldwide. Snakebite occurs as the result of an interaction between a human and a snake that elicits either a defensive response from the snake or, more rarely, a feeding response as the result of mistaken identity. Snakebite envenoming is therefor...
Article
Interpopulation venom variation has been widely documented in snakes across large geographical distances. This variability is known to markedly influence the effectiveness of snakebite therapy, as antivenoms manufactured against one population may not be effective against others. In contrast, the extent of intrapopulation venom variability, especia...
Article
Full-text available
Background Snakebite in India results in over 58,000 fatalities and a vast number of morbidities annually. The majority of these clinically severe envenomings are attributed to Russell’s viper ( Daboia russelii ), which has a near pan-India distribution. Unfortunately, despite its medical significance, the influence of biogeography on the compositi...
Article
Full-text available
Snakebite is a neglected tropical disease that inflicts severe socioeconomic burden on developing countries by primarily affecting their rural agrarian populations. India is a major snakebite hotspot in the world, as it accounts for more than 58,000 annual snakebite mortalities and over three times that number of morbidities. The only available tre...
Article
Full-text available
Background Snake venom composition is dictated by various ecological and environmental factors, and can exhibit dramatic variation across geographically disparate populations of the same species. This molecular diversity can undermine the efficacy of snakebite treatments, as antivenoms produced against venom from one population may fail to neutrali...
Article
Full-text available
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...
Article
Full-text available
The Common Krait (Bungarus caeruleus) shares a distribution range with many other ‘phenotypically-similar’ kraits across the Indian subcontinent. Despite several reports of fatal envenomings by other Bungarus species, commercial Indian antivenoms are only manufactured against B. caeruleus. It is, therefore, imperative to understand the distribution...
Article
Full-text available
The Common Krait (Bungarus caeruleus) shares a distribution range with many other ‘phenotypically-similar’ kraits across the Indian subcontinent. Despite several reports of fatal envenomings by other Bungarus species, commercial Indian antivenoms are only manufactured against B. caeruleus. It is, therefore, imperative to understand the distribution...
Article
Significance The venom of Australian funnel-web spiders contains δ-hexatoxins (δ-HXTXs) that exert fatal neurotoxic effects in humans by inhibiting inactivation of voltage-gated sodium channels, but their precise ecological role remains unclear. Sequencing of venom-gland transcriptomes from 10 funnel-web species uncovered 22 δ-HXTXs. Evolutionary a...
Article
Full-text available
Snake venoms are mixtures of toxins that vary extensively between and within snake species. This variability has serious consequences for the management of the world’s 1.8 million annual snakebite victims. Advances in ‘omic’ technologies have empowered toxinologists to comprehensively characterize snake venom compositions, unravel the molecular mec...
Article
Full-text available
Terminal selectors are transcription factors that control the morphological, physiological, and molecular features that characterize distinct cell types. Here, we show that, in the sea anemone Nematostella vectensis, NvPOU4 is expressed in post-mitotic cells that give rise to a diverse set of neural cell types, including cnidocytes and NvElav1-expr...
Preprint
Full-text available
Terminal selectors are transcription factors that control the morphological, physiological and molecular features that characterize distinct cell types. Here we use expression analyses and a transgenic reporter line to show that NvPOU4 is expressed in post-mitotic cells that give rise to a diverse set of neural cell types in the sea anemone Nematos...
Article
Full-text available
Background Snakebite in India causes the highest annual rates of death (46,000) and disability (140,000) than any other country. Antivenom is the mainstay treatment of snakebite, whose manufacturing protocols, in essence, have remained unchanged for over a century. In India, a polyvalent antivenom is produced for the treatment of envenomations from...
Article
Full-text available
Venom systems are key adaptations that have evolved throughout the tree of life and typically facilitate predation or defense. Despite venoms being model systems for studying a variety of evolutionary and physiological processes, many taxonomic groups remain understudied, including venomous mammals. Within the order Eulipotyphla, multiple shrew spe...
Article
Comprising of over a million described species of highly diverse invertebrates, Arthropoda is amongst the most successful animal lineages to have colonized aerial, terrestrial, and aquatic domains. Venom, one of the many fascinating traits to have evolved in various members of this phylum, has underpinned their adaptation to diverse habitats. Over...
Article
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Background: Cnidocytes are specialized cells that define the phylum Cnidaria. They possess an "explosive" organelle called cnidocyst that is important for prey capture and anti-predator defense. An extraordinary morphological and functional complexity of the cnidocysts has inspired numerous studies to investigate their structure and development. H...
Article
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Hymenopteran insects are infamous for their sting, and their ability to cause severe anaphylaxis and in some cases death. This allergic reaction is a result of allergens present in the venom. Hymenopterans have many common venom allergens, the most widespread of which include phospholipase A1, phospholipase A2, acid phosphatase, hyaluronidase, seri...
Chapter
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Venomous animals and their venoms have intrigued mankind for millennia. Venoms are complex cocktails of chemically diverse components that disrupt the physiological functioning of the victim to aid the venom‐producing animal in defence and/or feeding. Despite evolving independently on at least 30 occasions in the animal kingdom, venom exhibits rema...
Article
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Little is known about venom in young developmental stages of animals. The appearance of toxins and stinging cells during early embryonic stages in the sea anemone Nematostella vectensis suggests that venom is already expressed in eggs and larvae of this species. Here, we harness transcriptomic, biochemical and transgenic tools to study venom produc...
Preprint
Little is known about venom in young developmental stages of animals. The appearance of stinging cells in very early life stages of the sea anemone Nematostella vectensis suggests that toxins and venom are synthesized already in eggs, embryos and larvae of this species. Here we harness transcriptomic and biochemical tools as well as transgenesis to...
Preprint
Full-text available
Specialized neurons called cnidocytes define the phylum Cnidaria. They possess an ‘explosive’ organelle called cnidocyst that is important for prey capture and antipredator defense. An extraordinary morphological and functional complexity of the cnidocysts has inspired numerous studies to investigate their structure and development. However, the tr...
Chapter
Full-text available
Understanding the nature and strength of natural selection that influences the evolution of genes is one of the major aspects of modern evolutionary biological studies. Animal venoms are complex cocktails of biologically active compounds that are secreted in a specialized gland and actively delivered to the target animal through the infliction of a...
Article
Animal venom is a complex cocktail of bioactive chemicals that traditionally drew interest mostly from biochemists and pharmacologists. However, in recent years the evolutionary and ecological importance of venom is realized as this trait has direct and strong influence on interactions between species. Moreover, venom content can be modulated by en...
Book
Venom research and technology has advanced greatly, rapidly transforming the area of reptile venom. Research developments-like the development of molecular systematics-provide the framework necessary to reconstruct the evolutionary history of glands and fangs. Such research developments result in a fundamental shift in scientists' understanding of...
Chapter
Full-text available
Understanding the nature and strength of natural selection that influences the evolution of genes is one of the major aspects of modern evolutionary biological studies. Animal venoms are complex cocktails of biologically active compounds that are secreted in a specialized gland and actively delivered to the target animal through the infliction of a...
Article
Full-text available
Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific...
Article
Full-text available
Research into snake venoms has revealed extensive variation at all taxonomic levels. Lizard venoms, however, have received scant research attention in general, and no studies of intraclade variation in lizard venom composition have been attempted to date. Despite their iconic status and proven usefulness in drug design and discovery, highly venomou...
Article
Full-text available
Assessing the distribution, abundance and demographic ratios of endangered and elusive co-occurring carnivore species at a landscape level is important for their continued survival. Despite potential to determine distribution and dietary analyses, use of faecal samples has been relatively limited in the context of multiple sympatric species living...
Article
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Among the major goals of research in evolutionary biology are the identification of genes targeted by natural selection and understanding how various regimes of evolution affect the fitness of an organism. In particular, adaptive evolution enables organisms to adapt to changing ecological factors such as diet, temperature, habitat, predatory pressu...
Article
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Venomous animals are thought to inject the same combination of toxins for both predation and defence, presumably exploiting conserved target pharmacology across prey and predators. Remarkably, cone snails can rapidly switch between distinct venoms in response to predatory or defensive stimuli. Here, we show that the defence-evoked venom of Conus ge...
Article
Full-text available
Spiders have evolved pharmacologically complex venoms that serve to rapidly subdue prey and deter predators. The major toxic factors in most spider venoms are small, disulfide-rich peptides. While there is abundant evidence that snake venoms evolved by recruitment of genes encoding normal body proteins followed by extensive gene duplication accompa...
Article
Full-text available
Neurotrophins are a diverse class of structurally related proteins, essential for neuronal development, survival, plasticity and regeneration. They are characterized by major family members, such as the nerve growth factors (NGF), brain-derived neurotrophic factors (BDNF) and neurotrophin-3 (NT-3), which have been demonstrated here to lack coding s...
Article
The episodic nature of natural selection and the accumulation of extreme sequence divergence in venom-encoding genes over long periods of evolutionary time can obscure the signature of positive Darwinian selection. Recognition of the true biocomplexity is further hampered by the limited taxon selection, with easy to obtain or medically important sp...
Article
Although known for their potent venom and ability to prey upon both invertebrate and vertebrate species, the Barychelidae spider family has been entirely neglected by toxinologists. In striking contrast, the sister family Theraphosidae (commonly known as tarantulas), which last shared a most recent common ancestor with Barychelidae over 200 million...
Article
Full-text available
Despite the unparalleled diversity of venomous snakes in Australia, research has concentrated on a handful of medically significant species and even of these very few toxins have been fully sequenced. In this study, venom gland transcriptomes were sequenced from eleven species of small Australian elapid snakes, from eleven genera, spanning a broad...
Data
Full-text available
Neurotrophins are a diverse class of structurally related proteins, essential for neuronal development, survival, plasticity and regeneration. They are characterized by major family members, such as the nerve growth factors (NGF), brain-derived neurotrophic factors (BDNF) and neurotrophin-3 (NT-3), which have been demonstrated here to lack coding s...
Article
Full-text available
Although snake venoms have been the subject of intense research, primarily because of their tremendous potential as a bioresource for design and development of therapeutic compounds, some specific groups of snakes, such as the genus Atractaspis, have been completely neglected. To date only limited number of toxins, such as sarafotoxins have been we...
Article
Full-text available
Three-finger toxins (3FTx) represent one of the most abundantly secreted and potently toxic components of colubrid (Colubridae), elapid (Elapidae) and psammophid (Psammophiinae subfamily of the Lamprophidae) snake venom arsenal. Despite their conserved structural similarity, they perform a diversity of biological functions. Although they are theori...
Article
While vampire bat oral secretions have been the subject of intense research, efforts have concentrated only on two components: DSPA (Desmodus salivary plasminogen activator) and Draculin. The molecular evolutionary history of DSPA has been elucidated, while conversely draculin has long been known from only a very small fragment and thus even the ba...