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Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom.

Nekaris KA, Moore RS, Rode EJ, Fry BG - J Venom Anim Toxins Incl Trop Dis (2013)

Bottom Line: In a comparison of N. pygmaeus and N. coucang, 212 and 68 compounds were found, respectively.The least evidence is found for the hypothesis that loris venom evolved to kill prey.During the Miocene when both slow lorises and cobras migrated throughout Southeast Asia, the evolution of venom may have been an adaptive strategy against predators used by slow lorises as a form of Müllerian mimicry with spectacled cobras.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nocturnal Primate Research Group, Oxford Brookes University, Oxford OX3 0BP, UK. anekaris@brookes.ac.uk.

ABSTRACT
Only seven types of mammals are known to be venomous, including slow lorises (Nycticebus spp.). Despite the evolutionary significance of this unique adaptation amongst Nycticebus, the structure and function of slow loris venom is only just beginning to be understood. Here we review what is known about the chemical structure of slow loris venom. Research on a handful of captive samples from three of eight slow loris species reveals that the protein within slow loris venom resembles the disulphide-bridged heterodimeric structure of Fel-d1, more commonly known as cat allergen. In a comparison of N. pygmaeus and N. coucang, 212 and 68 compounds were found, respectively. Venom is activated by combining the oil from the brachial arm gland with saliva, and can cause death in small mammals and anaphylactic shock and death in humans. We examine four hypotheses for the function of slow loris venom. The least evidence is found for the hypothesis that loris venom evolved to kill prey. Although the venom's primary function in nature seems to be as a defense against parasites and conspecifics, it may also serve to thwart olfactory-orientated predators. Combined with numerous other serpentine features of slow lorises, including extra vertebra in the spine leading to snake-like movement, serpentine aggressive vocalisations, a long dark dorsal stripe and the venom itself, we propose that venom may have evolved to mimic cobras (Naja sp.). During the Miocene when both slow lorises and cobras migrated throughout Southeast Asia, the evolution of venom may have been an adaptive strategy against predators used by slow lorises as a form of Müllerian mimicry with spectacled cobras.

No MeSH data available.


Related in: MedlinePlus

NH2-terminal amino acid sequences of the pygmy loris α- and β-chains that make up the 18k major peptide of brachial gland exudate. (A) Comparison between the pygmy loris α-chain sequence and members from each clade of the α-chain superfamily: 1. secretoglobin (3288868); 2. mouse salivary androgen binding protein (19919338); 3. mouse putative protein 20948528; 4. loris brachial gland secretion; 5. domestic cat allergen; 6. human genome putative protein; 7. uteroglobin (6981694); and 8. lipophilin (5729909). Numbers refer to NCBI accession numbers. Homologous amino acids are highlighted in grey. (B) Comparison between the pygmy loris β-chain sequence and two members with similar β-chains. 1. domestic cat allergen (423192); 2. loris brachial gland secretion β-chain; and 3. mouse salivary protein (19353044).
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Figure 4: NH2-terminal amino acid sequences of the pygmy loris α- and β-chains that make up the 18k major peptide of brachial gland exudate. (A) Comparison between the pygmy loris α-chain sequence and members from each clade of the α-chain superfamily: 1. secretoglobin (3288868); 2. mouse salivary androgen binding protein (19919338); 3. mouse putative protein 20948528; 4. loris brachial gland secretion; 5. domestic cat allergen; 6. human genome putative protein; 7. uteroglobin (6981694); and 8. lipophilin (5729909). Numbers refer to NCBI accession numbers. Homologous amino acids are highlighted in grey. (B) Comparison between the pygmy loris β-chain sequence and two members with similar β-chains. 1. domestic cat allergen (423192); 2. loris brachial gland secretion β-chain; and 3. mouse salivary protein (19353044).

Mentions: Liquid chromatography/mass spectrometry (LC/MS) analysis of the brachial gland secretion from both species also revealed that each contained a single dominant protein component, molecular weight 17.6 k (Figure 3). Both taxa contained two isoforms (N. pygmaeus – 17671 and 17601 daltons; N. coucang – 17649 and 17610 daltons). Reduction of the disulfide bonds in the 17.6k peptide revealed that it was a heterodimer of two smaller peptides, molecular weights 7.8 kDa (α-chain) and 9.8 kDa (β-chain) linked together by two disulfide bridges. Sequencing of the α/β-chains showed that the loris brachial gland peptide is a new member of the secretoglobin (uteroglobin/Clara cell 10k) family. As found by Krane et al.[18], loris peptide was assigned to subfamily 4, with a close sequence homology with domestic cat Fel-d1 chain I peptide [19,20] (Figure 4 A and – B). The secretoglobin family is characterized by small lipophilic peptides found as major constituents in a variety of mammalian secretions. These proteins are all α/β-homo- and heterodimers stabilized by two or three intramolecular cystine disulfide bonds. In what is termed the uteroglobin-fold, the α- and β- monomers are formed from grouping four α-helices, and (for the two monomers) the combined eight α-helix bundle folds to form a pocket for the binding of different hydrophobic molecules [21].


Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom.

Nekaris KA, Moore RS, Rode EJ, Fry BG - J Venom Anim Toxins Incl Trop Dis (2013)

NH2-terminal amino acid sequences of the pygmy loris α- and β-chains that make up the 18k major peptide of brachial gland exudate. (A) Comparison between the pygmy loris α-chain sequence and members from each clade of the α-chain superfamily: 1. secretoglobin (3288868); 2. mouse salivary androgen binding protein (19919338); 3. mouse putative protein 20948528; 4. loris brachial gland secretion; 5. domestic cat allergen; 6. human genome putative protein; 7. uteroglobin (6981694); and 8. lipophilin (5729909). Numbers refer to NCBI accession numbers. Homologous amino acids are highlighted in grey. (B) Comparison between the pygmy loris β-chain sequence and two members with similar β-chains. 1. domestic cat allergen (423192); 2. loris brachial gland secretion β-chain; and 3. mouse salivary protein (19353044).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852360&req=5

Figure 4: NH2-terminal amino acid sequences of the pygmy loris α- and β-chains that make up the 18k major peptide of brachial gland exudate. (A) Comparison between the pygmy loris α-chain sequence and members from each clade of the α-chain superfamily: 1. secretoglobin (3288868); 2. mouse salivary androgen binding protein (19919338); 3. mouse putative protein 20948528; 4. loris brachial gland secretion; 5. domestic cat allergen; 6. human genome putative protein; 7. uteroglobin (6981694); and 8. lipophilin (5729909). Numbers refer to NCBI accession numbers. Homologous amino acids are highlighted in grey. (B) Comparison between the pygmy loris β-chain sequence and two members with similar β-chains. 1. domestic cat allergen (423192); 2. loris brachial gland secretion β-chain; and 3. mouse salivary protein (19353044).
Mentions: Liquid chromatography/mass spectrometry (LC/MS) analysis of the brachial gland secretion from both species also revealed that each contained a single dominant protein component, molecular weight 17.6 k (Figure 3). Both taxa contained two isoforms (N. pygmaeus – 17671 and 17601 daltons; N. coucang – 17649 and 17610 daltons). Reduction of the disulfide bonds in the 17.6k peptide revealed that it was a heterodimer of two smaller peptides, molecular weights 7.8 kDa (α-chain) and 9.8 kDa (β-chain) linked together by two disulfide bridges. Sequencing of the α/β-chains showed that the loris brachial gland peptide is a new member of the secretoglobin (uteroglobin/Clara cell 10k) family. As found by Krane et al.[18], loris peptide was assigned to subfamily 4, with a close sequence homology with domestic cat Fel-d1 chain I peptide [19,20] (Figure 4 A and – B). The secretoglobin family is characterized by small lipophilic peptides found as major constituents in a variety of mammalian secretions. These proteins are all α/β-homo- and heterodimers stabilized by two or three intramolecular cystine disulfide bonds. In what is termed the uteroglobin-fold, the α- and β- monomers are formed from grouping four α-helices, and (for the two monomers) the combined eight α-helix bundle folds to form a pocket for the binding of different hydrophobic molecules [21].

Bottom Line: In a comparison of N. pygmaeus and N. coucang, 212 and 68 compounds were found, respectively.The least evidence is found for the hypothesis that loris venom evolved to kill prey.During the Miocene when both slow lorises and cobras migrated throughout Southeast Asia, the evolution of venom may have been an adaptive strategy against predators used by slow lorises as a form of Müllerian mimicry with spectacled cobras.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nocturnal Primate Research Group, Oxford Brookes University, Oxford OX3 0BP, UK. anekaris@brookes.ac.uk.

ABSTRACT
Only seven types of mammals are known to be venomous, including slow lorises (Nycticebus spp.). Despite the evolutionary significance of this unique adaptation amongst Nycticebus, the structure and function of slow loris venom is only just beginning to be understood. Here we review what is known about the chemical structure of slow loris venom. Research on a handful of captive samples from three of eight slow loris species reveals that the protein within slow loris venom resembles the disulphide-bridged heterodimeric structure of Fel-d1, more commonly known as cat allergen. In a comparison of N. pygmaeus and N. coucang, 212 and 68 compounds were found, respectively. Venom is activated by combining the oil from the brachial arm gland with saliva, and can cause death in small mammals and anaphylactic shock and death in humans. We examine four hypotheses for the function of slow loris venom. The least evidence is found for the hypothesis that loris venom evolved to kill prey. Although the venom's primary function in nature seems to be as a defense against parasites and conspecifics, it may also serve to thwart olfactory-orientated predators. Combined with numerous other serpentine features of slow lorises, including extra vertebra in the spine leading to snake-like movement, serpentine aggressive vocalisations, a long dark dorsal stripe and the venom itself, we propose that venom may have evolved to mimic cobras (Naja sp.). During the Miocene when both slow lorises and cobras migrated throughout Southeast Asia, the evolution of venom may have been an adaptive strategy against predators used by slow lorises as a form of Müllerian mimicry with spectacled cobras.

No MeSH data available.


Related in: MedlinePlus