Biomedical subjects

J Gessner

Publications and source records attributed to J Gessner.

16 recordsLinked to original sources

PubMed2006

The role of the IGF-I system for vitellogenesis in maturing female sterlet, Acipenser ruthenus Linnaeus, 1758.

Transition from previtellogeneic to vitellogenic oocyte growth is a critical phase for folliculogenesis in sturgeon and may often be postponed for several years. Recent findings on the involvement of insulin-like growth factor I (IGF-I) in cell differentiation processes of oocyte follicle and ovarian steroidogenesis of teleosts in vitro led to the hypothesis that paracrine IGF-I could function as a potential trigger in vivo. For the first time, IGF-I and its corresponding receptor (IGF-IR) were identified in a non-teleostean fish. Real-time PCR assays for IGF-I and IGF-IR mRNA were established, normalising mRNA expression of the target genes to beta-microglobulin (beta2m). We clearly show that expression of IGF-I in the gonad is a substantial source for IGF-I-mediated effects in follicles compared to liver, brain, muscle and adipose tissue. Among these tissues, IGF-IR mRNA was highest in the gonad. With regard to different cohorts of coexisting follicles, highest expression of IGF-I and IGF-IR were met in developing follicles, indicating that IGF-I functions as an intraovarian modulator of follicle faith. Comparing previtellogenic follicles in females that matured within two years with non-maturing females f the same age, revealed an increases of 2.3-fold for IGF-I and 2.8-fold for IGF-IR mRNA expression in maturing females. These findings implicate an important role of paracrine IGF-I in early vitellogenesis and identify it as candidate vitellogenesis inducing factor (VIF), determining the faith of the follicle.

Animals↗

PubMed2003

Nonconcordant evolutionary history of maternal and paternal lineages in Adriatic sturgeon.

Although analyses of intraspecific variability are an important prerequisite for species identification assays, only a few studies have focused on population genetics and historical biogeography of sturgeon species. Here we present the first study on genetic variability of the last remaining Adriatic sturgeon, Acipenser naccarii, derived from mitochondrial and nuclear DNA. Our mitochondrial DNA analyses arranged individuals into three distinguished mitochondrial DNA haplogroups (Po1, Po2 and Buna). Two haplogroups (Po1 and Buna) were correlated to geographical distribution, whereas the third (Po2) was not. It was, however, very closely related to one lineage of its Ponto-Caspian sister species, A. gueldenstaedtii. The distribution of nuclear markers (microsatellites and amplified fragment length polymorphism) was strongly correlated to geographical distribution. An assignment test based on nuclear data placed no specimen of A. naccarii to A. gueldenstaedtii and vice versa. Therefore, the presence of gueldenstaedtii-like haplotypes within the Po population is either the result of a postglacial introgression or an ancestral polymorphism and does not indicate a hybrid population. The most valuable tool for forensic species identification purposes is one diagnostic deletion separating all A. naccarii from A. gueldenstaedtii. As both A. naccarii populations are genetically differentiated, stocking of sturgeon from the Po River in Italy into waters of the Buna River would jeopardize the genetic differences between both populations and should thus be avoided.

Animals↗

PubMed2000

Chemical and biochemical composition of caviar from different sturgeon species and origins.

The chemical and biochemical composition of caviar in 22 specimens of wild caught and of 2 farmed animals were measured. The results include grain size, protein and fat content, fatty acid composition of triglycerides and phospholipids, as well as the concentrations of relevant heavy metals and chlorinated hydrocarbons. The average protein content varied between 26.2 and 31.1% (wet weight) and fat from 10.9 to 19.4% (wet weight) with lowest values for caviar from farmed sturgeon. The triglycerides and phospholipids contained more n-3 fatty acids, especially eicosapentaenoic and docosahexaenoic acid than n-6 fatty acids. The copper and zinc concentrations varied between 1.20 and 1.69 and 10.3 and 12.4 mg/kg (wet weight), respectively. These values reflect the elevated requirement of sturgeons for these components. Lead content varied between 0.06 and 0.15 mg/kg (wet weight). The cadmium concentrations were less than 5 micrograms/kg (wet weight) leading to the conclusion that no accumulation took place in the eggs. The concentrations of sigma DDT and sigma PCB were extremely high in caviar from Huso huso compared to the samples of the other species thus reflecting the different food habits leading to increased bio-accumulation.

Animals↗

PubMed1983