排序方式: 共有145条查询结果,搜索用时 15 毫秒
141.
Dunja Treyer Peter Linderoth Thomas Liebl Manfred Pegel Ulrike Weiler Rolf Claus 《European Journal of Wildlife Research》2012,58(1):373-378
Wild boars shot in a hunting area in Baden-Württemberg during three consecutive years (148 males, 205 females) were analysed
for insulin-like growth factor 1 (IGF-I) concentrations in blood plasma. Gonadal steroids were determined either in blood
plasma (females, progesterone) or adipose tissue (males, androstenone). The age (estimated by the dental pattern) and the
carcass weight were recorded. From 159 out of the 353 animals, the stomach content was analysed for total energy and digestibility.
Sex differences in carcass weight were only significant in animals above the age of 14 months. Carcass weight was significantly
correlated with IGF-I in males but not in females. IGF-I revealed a sex-specific seasonal pattern (maximum concentrations
in males, June; in females, October). Additionally, as indicated by analyses of the stomach content, the digestibility of
the food had affected IGF-I concentrations. Gonadal steroids revealed the well-known seasonal pattern described in other studies
and did not point to a more aseasonal pattern of reproduction when energy supply is artificially increased by baiting. 相似文献
142.
143.
Dunja Lukić Robert Ptacnik Csaba F. Vad Csenge Pόda Zsόfia Horváth 《Freshwater Biology》2020,65(2):226-239
- Omnivory is widespread in food webs, with an important stabilising effect. The strength of omnivorous trophic interactions may change considerably with changes in the local environment.
- Shallow temporary waters are often characterised by high levels of inorganic turbidity that may directly limit the food uptake of filter-feeding organisms, but there is little evidence on how it might affect omnivorous species. Anostracans are key species of temporary waters and recent evidence suggests that these organisms are omnivorous consumers of both phyto- and zooplankton.
- Using Branchinecta orientalis as a model species, our aim was to test how turbidity affects the feeding of an omnivorous anostracan. To do this, we used short-term feeding experiments and stable isotope analyses, with animals collected from soda pans in eastern Austria. In the feeding experiments, algae and zooplankton were offered as food either separately or in combination. The prey type treatments were crossed with turbidity levels in a factorial design.
- There was a pronounced decrease in the ingested algal biomass with increasing turbidity. Conversely, ingestion rates on zooplankton were less affected by turbidity. Stable isotope analyses from field material supported our experimental results by showing a positive relationship of the trophic position of anostracans and the trophic niche of the communities with turbidity.
- Our results show that turbidity modulates the intraguild trophic relationship between anostracans and their prey by shifting the diet of anostracans from more herbivorous in transparent to more carnivorous in turbid waters. Thus, inorganic turbidity might also have a community-shaping role in plankton communities of temporary waters through altering trophic relationships.
144.
Matthias Stöck Jana Ustinova Dunja K. Lamatsch Manfred Schartl Nicolas Perrin Craig Moritz 《Evolution; international journal of organic evolution》2010,64(4):944-959
The rise and consequences of polyploidy in vertebrates, whose origin was associated with genome duplications, may be best studied in natural diploid and polyploid populations. In a diploid/tetraploid (2n/4n) geographic contact zone of Palearctic green toads in northern Kyrgyzstan, we examine 4ns and triploids (3n) of unknown genetic composition and origins. Using mitochondrial and nuclear sequence, and nuclear microsatellite markers in 84 individuals, we show that 4n (Bufo pewzowi) are allopolyploids, with a geographically proximate 2n species (B. turanensis) being their maternal ancestor and their paternal ancestor as yet unidentified. Local 3n forms arise through hybridization. Adult 3n mature males (B. turanensis mtDNA) have 2n mothers and 4n fathers, but seem distinguishable by nuclear profiles from partly aneuploid 3n tadpoles (with B. pewzowi mtDNA). These observations suggest multiple pathways to the formation of triploids in the contact zone, involving both reciprocal origins. To explain the phenomena in the system, we favor a hypothesis where 3n males (with B. turanensis mtDNA) backcross with 4n and 2n females. Together with previous studies of a separately evolved, sexually reproducing 3n lineage, these observations reveal complex reproductive interactions among toads of different ploidy levels and multiple pathways to the evolution of polyploid lineages. 相似文献
145.
Determination of volatile products of human colon cell line metabolism by GC/MS analysis 总被引:2,自引:0,他引:2
Dunja Zimmermann Michelle Hartmann Mary Pat Moyer Jürgen Nolte Jörg Ingo Baumbach 《Metabolomics : Official journal of the Metabolomic Society》2007,3(1):13-17
Colon cancer is one of the most reasons for cancer death worldwide. Thus, it is important to find new prognostic and diagnostic
marker, as well as to throw light on the special metabolic pathways of colon cancer cells. This paper highlights for the first
time some qualitative differences in the profiles of the volatile metabolites of colon cancer cell lines SW 480 (grade IV,
Duke B) and SW 1116 (grade II, Duke A) among themselves and in comparison to the normal colon cell line NCM460, which are
mostly represented by ketones and alcohols. These results, which were obtained by applying solid phase micro extraction (SPME)
and combined gas chromatography/mass spectrometry (GC/MS), are consistent with Warburg’s hypothesis because the found reaction
products may indicate that the cancer cells show the Crabtree’s effect. Furthermore, compounds like undecan-2-ol and pentadecan-2-one
were associated for the first time with the human metabolism. In summary, these findings indicate that the metabolism of colon
cancer cells differs extremely from the metabolism of healthy cells and it changes during the progress of the disease. Compounds
that are present in the breath, the blood and the tissue of patients represent the differences and they can serve as new biomarker
for colon cancer in future. 相似文献