[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Non-dino papers: Taeniodont origins and python venom glands



From: Ben Creisler
bcreisler@gmail.com


A couple of recent non-dino papers that may be of interest:

Deborah L. Rook & John P. Hunter (2013)
Rooting Around the Eutherian Family Tree: the Origin and Relations of
the Taeniodonta.
Journal of Mammalian Evolution (advance online publication)
doi: 10.1007/s10914-013-9230-9
http://link.springer.com/article/10.1007/s10914-013-9230-9

Placing early groups into the overall phylogeny of eutherian mammals
can be challenging, particularly when the group does not have extant
members. We investigated the relationships of the Taeniodonta, an
extinct group from the Late Cretaceous through Paleogene of North
America. This group has a few purported close relatives, including
Cimolestes, Procerberus, and Alveugena, that may form a sequence of
ancestors and descendants. The leading hypothesis is that Procerberus
gave rise to taeniodonts through Alveugena. We test this hypothesis
and analyze relations to known stem and crown Eutheria to determine
the place of taeniodonts in eutherian phylogeny. Cladistic analyses
were performed using previously published characters and datasets,
namely a taeniodont/cimolestid specific dataset and a reanalysis of
Wible and colleagues (2009), with added taxa for both. Our studies
suggest that taeniodonts arose from Cimolestes through Alveugena, that
Procerberus is more distantly related to taeniodonts, and that
taeniodonts and their relatives are stem eutherians. We diagnose the
Taeniodonta based on these analyses. Other Paleogene groups,
especially those allied with Cimolestes such as tillodonts and
pantolestans, merit further study. Our findings indicate that stem
eutherians such as the Taeniodonta, in addition to crown eutherians,
continued to diversify during the Paleogene.



===



Venom glands identified in pythons, boas (open access paper)
Bryan G. Fry, Eivind A. B. Undheim, Syed A. Ali, Jordan Debono, Holger
Scheib, Tim Ruder, Timothy N. W. Jackson, David Morgenstern, Luke
Cadwallader, Darryl Whitehead, Rob Nabuurs, Louise van der Weerd,
Nicolas Vidal, Kim Roelants, Iwan Hendrikx, Sandy Pineda Gonzalez,
Alun Jones, Glenn F. King, Agostinho Antunes and Kartik Sunagar (2013)
Squeezers and leaf-cutters: differential diversification and
degeneration of the venom system in toxicoferan reptiles.
Molecular & Cellular Proteomics (advance online publication)
doi: 10.1074/mcp.M112.023143
http://www.mcponline.org/content/early/2013/04/01/mcp.M112.023143.long


While it has been established that all toxicoferan squamates share a
common venomous ancestor, it has remained unclear whether the
maxillary and mandibular venom glands are evolving on separate gene
expression trajectories or if they remain under shared genetic
control. We show that identical transcripts are simultaneously
expressed not only in the mandibular and maxillary glands, but also in
the enigmatic snake rictal gland. Toxin molecular frameworks recovered
in this study were three-finger toxin (3FTx), CRiSP, crotamine
(beta-defensin), cobra venom factor, cystatin, epididymal secretory
protein, kunitz, L-amino-acid oxidase, lectin, renin aspartate
protease, veficolin, and vespryn. We also discovered a novel
low-molecular weight disulphide bridged peptide class in pythonid
glands. In the iguanian lizards, the most highly expressed are
potentially antimicrobial in nature [crotamine (beta-defensin) and
cystatin], with crotamine (beta-defensin) also the most diverse.
However, a number of proteins characterised from anguimorph lizards
and caenophidian snakes with hemotoxic or neurotoxic activities were
also recruited basally and remain expressed, albeit in low levels,
even in the iguanian lizards. In contrast, the basal snakes express
3FTx and lectin toxins as the dominant transcripts. Even in the
constricting pythonid and boid snakes, where the glands are
predominantly mucous-secreting, low-levels of toxin transcripts can be
detected. Venom thus appears to play little role in feeding behaviour
of most iguanian lizards or the powerful constricting snakes, and the
low levels of expression argue against a defensive role. However,
clearly the incipient or secondarily atrophied venom systems of these
taxa may be a source of novel compounds useful in drug design and
discovery.