|dc.description.abstracteng||The goal of this thesis was to explore the potential
of different biochemical and molecular markers to
discriminate different sturgeon species. Blood samples
were collected from the Eurasian sturgeons Acipenser
baerii (n = 125), A. gueldenstaedtii (n = 91), A.
ruthenus (n = 38), A. stellatus (n = 42) and Huso huso
(n = 72). Additionally four samples of A. persicus as
well as two samples of A. naccarii and Polyodon
spathula were available Furthermore, blood samples of
the hybrids A. baerii x A. ruthenus, H. huso x A.
gueldenstaedtii, H. huso x A. ruthenus and (H. huso x
A. ruthenus) x A. gueldenstaedtii have been at
disposal. Alltogether 13 different biochemical markers
occuring in the blood were investigated at A. baerii,
A., gueldenstaedtii, A. ruthenus, A. stellatus and H.
huso. Of these solely the allozyme system
phosphoglucomutase (PGM) was characteristic for one
sturgeon species, A. stellatus. Specimens of this
species were fixed at allele c not observed in
individuals of the other four sturgeon taxa. Several
different molecular methods were investigated in this
study, like AFLP, inter-SSR PCR, RAPD and SINE-PCR.
Furthermore, microsatellite loci as well as the
mitochondrial cytochrome b gene have been examined.
Solely the microsatellite locus LS-39 was identified as
diagnostic nuclear marker for A. stellatus. All
specimens as well as an analyzed caviar lot of the
species were fixed at the allele of 111 bp. This allele
was not observed in other sturgeons investigated. With
respect to the experimental conditions the techniques
AFLP, inter-SSR PCR and SINE-PCR were unabel to
identify the invstigated species A. baerii, A.
ruthenus, A. stellatus and H. huso or A. ruthenus, A.
stellatus and H. huso, respectively. On the other hand
neither a discrimination of sturgeon hybrids nor the
assignment of hybrids to parental species was possible.
Marked sequence differences were observed among the
species A. ruthenus, A. stellatus, A. transmontanus, H.
huso, P. spathula and the sisterspecies encomprised
within the genus Scahirhynchus at the mitochondrial
cytochrome b gene. Due to the well known occurence of
natural variability of nucleotide sequences among
specimens within species, statements concerning
interspecific conserved nucleotide substitutions could
not be drawn. The use of these nucleotide substititions
as diagnostic features has to be proven at a larger
number of wild specimens originating from different
locations. However, the fact that mitochondrial DNA is
inherited maternally has the disadvantage that hybrids
could not be identified. Furthermore, new aspects on
the ploidy level of different acipenseriform species
were retrieved and a closer view on the systematics of
Acipenseriformes was obtained by reconstructed