2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

We here describe the internal physiological functions and determine the
neurotransmitters involved in the formation of inducible morphological defenses in
Daphnia.
����214 Gerd Gäde
Peptide signalling in branchiopod crustaceans: the AKH/RPCH system in Daphnia
pulex
Authors: Gerd Gäde 1 , Heather G. Marco 1 , Lance A. Anders 1
Affiliation: 1 Zoology Department, University of Cape Town, Rondebosch, South Africa
Neuropeptide and peptide hormones are a well-studied group of signalling molecules
involved in regulating a variety of physiological processes in animlas. With the advent
of whole organism genome sequencing, it has become possible not only to predict
the sequence of such hormones, but also the potential receptor for such a ligand. By
using bioinformatic tools available and accessing sequence information in databases,
this has become a preferred methodological avenue to the classical chemistry and
biochemistry approaches, despite several short-comings to the in silico route. In our
study, we accessed the water flea Daphnia pulex genome data base to identify the
predicted, putative red pigment-concentrating hormone (Dappu-RPCH) and its
receptor (Dappu-RPCHR). We then designed primers to amplify, clone and sequence
these predicted products from total RNA extracted from two different D. pulex
ecotypes: one originating from Germany, and the other from South Africa. We show
distinct, repeatable differences in the preprohormone sequence deduced from the
whole genome data base information versus what we cloned from the German and
from the South African water fleas. These differences are not in the Dappu-RPCH
sequence but in the signal peptide and the precursor-related peptide. These
differences are very interesting, considering that the same species is being
investigated and surely reflect genomic differences that have arisen between the
different water flea clones used in this study. The source and the function of Dappu-
RPCH are still unknown. We attempt to address this aspect by reverse transcription
polymerase chain reaction with cDNA templates derived from different tissue types
in D. pulex.
Supported by NRF and URC of UC
����215 Faten Gabsi
A modeling approach to characterize population-level effects of sub-lethal
exposure to toxicants in Daphnia magna
Authors: Faten Gabsi 1 , Thomas Preuss 1
Affiliation: 1 RWTH Aachen University
In this study, we aim to determine how sub-lethal effects measured on individuals
affect population properties in Daphnia magna.
Toxicant-induced changes on individuals translate differently at the population level.
For instance, population decline may arise from simple affected individual-level
endpoints, whereas a significant influence on other endpoints might have negligible
impact on population size and/or structure.
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