CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S17
Plasticity of the gastrointestinal tract of the burmese python
Jean-Hervé Lignot, Cécile Helmstetter, Robert Pope, Alain
Ackermann and Stephen Secor
Institut Pluridisciplinaire Hubert Curien, UMR 7178 CNRS,
Département Ecologie, Physiologie et Ethologie, 23, rue Becquerel,
67087 Strasbourg Cedex 2, France
Morphological changes observed in the gastric and intestinal lining
of fed and fasting Burmese pythons were studied using
immunohistochemistry, Western blotting, scanning and
transmission electron microscopy techniques. In the stomach,
oxyntopeptic cells of fasting animals are filled with zymogen
granules and possess a thick tubulovesicular system that is
transformed into apical digitations projecting into the lumen of the
gastric crypts soon after feeding. This allows the proton pump
sequestered into the tubulovesiular system of fasting animals to
actively excrete proton ions immediately after ingestion of the prey.
In the intestine, fasting animals possess hypotrophied enterocytes
with small apical microvilli and numerous lysosomes and related
organelles such as numerous apical multivesicular bodies,
embodied particles and large lamellar bodies filled with concentric
rings of lipid membranes.
Fed individuals, however, show enlarged absorbing cells that can
be filled with lipids as well as elongated microvilli. A new cell type
within the mucosal epithelium is also described that has an apical
crypt. This cell type is only present in the proximal part of the
intestine, is connected to the b! asal membrane, is devoid of large
lipid droplets, possesses a large nucleus, and is less stained than
its neighbouring absorbing enterocytes. In fed animals the crypt is
usually filled with a multi-layered spheroid particle made of calcium
and phosphorus. Gut plasticity is therefore of crucial importance in
Burmese pythons and relies on rapid and massive morphofunctional
changes as well as cell components recycling and
trafficking.
Thermogenesis of digestion in juvenile burmese pythons
Jean-Hervé Lignot and Thibault Poolny
Institut Pluridisciplinaire Hubert Curien, UMR 7178 CNRS,
Département Ecologie, Physiologie et Ethologie, 23, rue Becquerel,
67087 Strasbourg Cedex 2, France
Burmese pythons experience dramatic increases in metabolism
during meal digestion that can directly modify thermogenesis.
Temperature data loggers were surgically implanted adjacent to
the stomach and small intestine or inserted inside the prey.
Infrared images of fasting pythons and up to 120 hours after
feeding were also collected from th! e snakes’ skin. The effects of
environmental temperature on postprandial thermogenesis were
evaluated by recording skin and body temperatures during the
digestion of a rodent meal equalling 20% of snake body mass at
room temperatures of 20, 25, 30, and 35°C. We also identified the
effects of meal size on thermogenesis by recording temperatures
following the ingestion of meals equalling 10, 20, or 30% of snake
body mass. At 20°C, skin and body temperatures of digesting
pythons were barely elevated above room temperature. Between
25 and 35°C, skin and body temperatures rapidly increase after
feeding and peaked 20-24 hours after feeding at 1–2.5°C above
room temperature. Thereafter, body temperatures remained
elevated before returning to room temperature 50-80 hours after
feeding. With an increase in meal size, pythons experience a
larger increase in skin and body temperatures and a longer
duration of elevated temperatures. For 10% meal, body
temperature rose by 1.2°C and remained elevated for 60 hours,
whereas for the 30% meals, body temperature increased by 2.5 °C
and remained elevated for 80 hours. A by-product of the work of
digestion, this endogenous production of heat is beneficial to the
python in increasing the rate of meal digestion and assimilation.
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Learning of a heterocolonial, heterospecific template in adult
workers of the wood ant, Formica rufa (Hymenoptera:
Formicidae): a neuropharmacological approach
Sylvie Marques and Stéphane Chameron
Laboratoire d’Ethologie Expérimentale et Comparée, UMR CNRS
7153, Université Paris 13, 99 Avenue JB Clément, 93430
Villetaneuse, France
Social insects are characterized by colonial closure that relies on
their ability to discriminate between nestmates and non-nestmates.
In ants, recognition mechanisms involve the matching of perceived
chemical cues to an internal template of colony odour, which has
been acquired during early adult life in many species. Intercolonial
relationships in ants can be ruled by the “dear-enemy effect”,
which consists in a differential treatment of familiar neighbours and
strangers. Such discrimination can arise either from differential
olfactory distance between close and distant strangers, or from
true learning process of neighbours’ colonial visa.
We present an experimental paradigm where heterospecific
colonies have been settled as neighbours in the lab. We monitored
agonistic behaviours in dyadic encounters before and after the
familiarisation period. Our results show that workers adjusted their
social behaviour to the stranger’s familiarity level, leading to the
conclusion that adult workers of the Formica rufa-group can form a
heterospecific, colony-specific template, in addition to the
homocolonial visa early learned.
From a cognitive point of view, heterocolonial visa acquisition is
probably based on an aversive conditioning process.
We investigated the role of dopamine, which is known to mediate
negative reinforcement in invertebrates, by providing experimental
ants with either dopamine or a dopaminergic antagonist
(fluphenazine). We report here first evidence that social odour
learning could indeed be correlated to dopaminergic activity.
We conclude that our paradigm of social odour learning in ants
provide a promising model for the investigation of the cognitive and
neuropharmacological bases of recognition mechanisms in social
insects.
Is the drop in the breeding success of white storks related to
a poorer reproductive ability of released captive birds ?
Sylvie Massemin-Challet 1 , Delphine Michard-Picamelot 2 , Joël M.
Durant 3 and Yvon Le Maho 1
1
CNRS, CEPE, UPR 9010, associated with Louis Pasteur
University, 23 rue Becquerel, F-67087 Strasbourg, France
2
Mission of Scientific and Technical Culture, ULP, Strasbourg,
France
3
Centre for Ecological and Evolutionary Synthesis (CEES),
Department of Biology, University of Oslo, P.O. Box 1050 Blindern,
NO-0316 Oslo, Norway
A decrease in populations of white storks has been observed in
Western Europe until 1950. Conservation steps were conducted by
releasing young storks born in captivity. In the Alsace region
(France), the reproductive success (number of fledglings) of
breeding pairs was, however, higher before than after
reintroduction with a population mainly constituted of birds
released from captivity. The aim of this three year study was to
determine if the breeding success in the field depends to the
realising of captive birds. Reproductive success was lower in
captive pairs than in free-living pairs both in the Alsace region and
other parts of France, where no reintroduction has been managed.
In captivity, food competition within brood had a negative effect on
the survival of nestlings and on the maximum gain of the two lasthatched
nestlings in broods. If no influence of hatching order was
observed on asymptotic body mass, this growth flexibility can have
an impact on the breeding efficacy of birds, as suggested by other
studies. In conclusion, one of the factors contributing to the drop of
reproductive success in areas with reintroduction management
may be the quality of future breeders released in the field. To
determine the consequences of overall reproductive success of
captive birds released in the field on the reproductive success of
the white stork population, we will compare the reproductive
success between released and wild birds.