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(Broaders et al., 1999; Weinstein et al., 1993). Previous investigations had suggested
the presence of postsynaptically active neurotoxins in other colubrid secretions, such
as those from
Boiga blandingi
(Blanding's tree snake—Broaders et al., 1999; Levinson
et al., 1976; Weinstein and Smith, 1993),
P. olfersii
(Prado-Franceschi et al., 1996),
Heterodon platirhinos
(eastern hognose snake; Young, 1992),
Thamnodynastes stigilis
(Lemoine et al., 2004a), and others. Recent electrophysiological investigations have dem-
onstrated the presence of neurotoxins in secretions from
Trimorphodon biscutatus
(lyre
snake),
Telescopus dhara
(large-eyed or Israeli cat snake),
Psammophis mossambicus
(olive whip snake) and several additional
Boiga
spp. (Lumsden et al., 2004) as well as
the African beaked snake,
Rhamphiophis oxyrhynchus
(Lumsden et al., 2005). In addi-
tion, the Duvernoy's secretion (“venom”) of some species, such as the Puerto Rican
racer,
Alsophis
(
Borikenophis
; Hedges et al., 2009)
portoricensis
, contains components
such as cysteine-rich secretory proteins (CRISPs) that probably function as ion chan-
nel regulating proteins. One of these had sequence homology with tigrin, a CRISP iso-
lated from venom of
R. tigrinus
(Weldon and Mackessy, 2010). Another CRISP isolated
from secretion of
P. patagoniensis
was myotoxic (Peichoto et al., 2009). “Helicopsin,” a
CRISP characterized from Duvernoy's secretion of
Helicops angulatus
(South American
or broad-banded water snake; water mapepire) caused rapid death of mice following i.p.
injection (minimal lethal dose was 0.4 mg/kg, tested in a small group of mice; Estrella
et al., 2010).
Some Duvernoy's secretions exhibit prey-specific immobilization functions. Neill
(1954) described the quiescent effect on prey of
Rhadinea flavilata
(pinewoods or
yellow-lipped snake) oral secretions. As a specific example, fish are a favored prey of
Helicops
spp. (South American water snakes). When fish are injected with oral secre-
tions from
Helicops
spp., they show decreased opercular activity and a 30-min period
of immobilization followed by death (Albolea et al., 2000). Reports of immobility and/
or death induced as a result of bites inflicted on squamate prey species by
Diadophis
punctatus
ssp. (ringneck snakes) suggest the use of Duvernoy's secretions in prey sub-
jugation (Anton, 1994; Gehlbach, 1974; Mackessy, 2002). O'Donnell et al. (2007)
reported lethal effects of
D. p. occidentalis
(northwestern ringneck snake) oral secre-
tions injected intra-abdominally into the natricine colubrid,
Thamnophis ordinoides
(northwestern gartersnake), a natural prey species. It is noteworthy that all doses used
by these investigators resulted in 100% mortality of the injected snakes within 3 h.
Several observers have reported active engagement of the enlarged posterior maxil-
lary teeth of
A. portoricensis
during prey capture with seized anoline lizards exhibiting
concomitantly decreased struggling movements (Rodriguez-Robles, 1992; Rodriguez-
Robles and Thomas, 1992; Weldon and Mackessy, 2010; see later). However, it can be
observed that often there is a wide variation in observations that are interpreted as use
of Duvernoy's secretions in prey handling. For example, oral secretions of
S. mikani
immobilized slugs (Salamão and Laporta-Ferreira, 1994), and a black-fronted nun-
bird (
Monasa nigrifrons
) grasped by a green vine snake (
Oxybelis fulgidus
), appeared
immobilized (without constriction) and was swallowed by the snake without signifi-
cant struggle (Endo et al., 2007). On the other hand, an
O. fulgidus
seized the head
of a large Central American whiptail lizard (
Ameiva festiva
), and held its “franti-
cally” moving prey for an estimated 15 min. The lizard succumbed shortly thereafter,
