Female Wagler's Pit Viper - Tropidolaemus wagleri

Taken at night in Singapore forest.

Tropidolaemus wagleri is a venomous pitviper species native to South-East Asia. No subspecies are currently recognized.[4] It is sometimes referred to as the temple viper because of its abundance around the Temple of the Azure Cloud in Malaysia.

This species is sexually dimorphic: the females grow to approximately 1 m (39 1⁄4 in) in total length, while males typically do not exceed 75 cm (29 1⁄2 in). They have a large triangular-shaped head, with a relatively thin body. They are almost entirely arboreal, and the tail is prehensile to aid in climbing.

They are found in a wide variety of colors and patterns, often referred to as "phases". In the past, some researchers classified the different phases as subspecies. The phases vary greatly from having a black or brown coloration as a base, with orange and yellow banding to others having a light green as the base color, with yellow or orange banding, and many variations therein.
The venom of Tropidolaemus wagleri contains 4 novel peptides (Waglerins 1-4). The Waglerins produce fatal respiratory paralysis of adult mice.[12][13] An initial study indicated that micromolar concentrations of Waglerin 1 act both pre- and postsynaptically to inhibit transmission across rat neuromuscular junctions.[14] However, Waglerin-1 is a more potent inhibitor of transmission across the mouse neuromuscular junction.[15] A subsequent study demonstrated that Waglerin-1 inhibited the adult mouse endplate response to acetylcholine with an IC50 of 50 nanomolar. In striking contrast, transmission across neuromuscular junctions of neonatal or transgenic mice lacking the adult acetylcholine receptor was not altered by micromolar concentrations of Waglerin-1. Biochemical studies demonstrated that the exquisite selectivity of Waglerin-1 for the adult mouse acetylcholine receptor relies upon several amino acid residues unique to the epsilon subunit of the adult mouse acetylcholine receptor.[17] Waglerin-1's selectivity for the epsilon-subunit containing acetylcholine receptor of adult mice is complemented by selectivity of small peptide toxins purified from the venom of Conus geographus and pergrandis for the gamma-subunit containing acetylcholine receptor of neonatal skeletal muscle. The Waglerins and complementary conotoxins are useful tools to discover the contribution of acetylcholine receptor subunits to synaptogenesis.[20] In addition, study of the Waglerins and related toxic peptides may lead to the discovery of novel molecular targets for drug development. While Waglerin-1 interacts with other members of the ligand-gated superfamily of ion channels, the potency is much less than for inhibition of the adult mouse muscle acetylcholine receptor. Structural study suggests that Waglerin-1 may undergo molecular rearrangement that allows for binding to multiple receptors. The actions of Waglerin-1 reverse upon removal of the peptide.