Reptile Forum, Reptile Classifieds - CaptiveBred

[Scott W]

EARLY EVOLUTION OF THE VENOM SYSTEM IN LIZARDS AND SNAKES
2006 Nature 439: 584-588

Bryan G. Fry, Nicolas Vidal, Janette A. Norman, Freek J. Vonk, Holger
Scheib, S.
F. Ryan Ramjan, Sanjaya Kuruppu, Kim Fung, S. Blair Hedges, Michael K.
Richardson, Wayne. C. Hodgson, Vera Ignjatovic, Robyn Summerhayes, & Elazar
Kochva

Abstract: Among extant reptiles only two lineages are known to have evolved
venom delivery systems, the advanced snakes and helodermatid lizards (Gila
Monster and Beaded Lizard) 1. Evolution of the venom system is thought to
underlie the impressive radiation of the advanced snakes (2,500 of 3,000
snake
species) 2-5. In contrast, the lizard venom system is thought to be
restricted to
just two species and to have evolved independently from the snake venom
system1. Here we report the presence of venom toxins in two additional
lizard
lineages (Monitor Lizards and Iguania) and show that all lineages possessing
toxin-secreting oral glands form a clade, demonstrating a single early
origin of
the venom system in lizards and snakes. Construction of gland
complementary-DNA libraries and phylogenetic analysis of transcripts
revealed
that nine toxin types are shared between lizards and snakes. Toxinological
analyses of venom components from the Lace Monitor Varanus varius showed
potent effects on blood pressure and clotting ability, bioactivities
associated
with a rapid loss of consciousness and extensive bleeding in prey. The
iguanian
lizard Pogona barbata retains characteristics of the ancestral venom system,
namely serial, lobular non-compound venom-secreting glands on both the upper
and lower jaws, whereas the advanced snakes and anguimorph lizards
(including
Monitor Lizards, Gila Monster and Beaded Lizard) have more derived venom
systems characterized by the loss of the mandibular (lower) or maxillary
(upper)
glands. Demonstration that the snakes, iguanians and anguimorphs form a
single
clade provides overwhelming support for a single, early origin of the venom
system in lizards and snakes. These results provide new insights into the
evolution of the venom system in squamate reptiles and open new avenues for
biomedical research and drug design using hitherto unexplored venom
proteins.

A pdf of this article can be accessed and downloaded at the CNAH pdf
library. Go
to:

http://www.cnah.org/cnah_pdf.asp
_________________

Please DO NOT pm orders for reptiles, send email instead scott@captivebred.co.uk

[Jas]

[Nelson]

[Jas]

No ive not seen vitticeps mentioned, i just assumed it was them forum talk.