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The thesis deals with ions stored in an electrostatic ion beam trap. In the first part of the thesis the so-called self-synchronization effect is discussed. It is demonstrated that the time a bunch of injected ions is conserved by the self-synchronization effect depends on the number of injected ions. In the second part of the thesis the cooling of small anionic cobalt and copper clusters is addressed. Measurements on anionic copper clusters consisting of four to seven atoms are presented and the decay of hot clusters is observed in order to draw conclusions on the internal temperature and the cooling process itself. Afterwards measurements on Co4- are discussed and a measurement scheme based on laser induced delayed electron emission is presented enabling to monitor the internal energy distribution of the clusters over storage time in a temperature-controlled environment. The cooling of initially hot clusters as well as the heating of initially cold clusters were observed.
We analyzed the proteomic response of the Gram-negative fish pathogen A. salmonicida to iron limitation, an elevated incubation temperature, and the antibiotic florfenicol. Proteins from different subcellular fractions (cytosol, inner membrane, outer membrane, extracellular and outer membrane vesicles) were enriched and analyzed. We identified several iron-regulated proteins that were not reported in the literature for A. salmonicida before. We could also show that hemolysin, an oxidative-stress-resistance chaperone, a putative hemin receptor, an M36 peptidase, and an uncharacterized protein were significantly higher in abundance not only under iron limitation but also with an elevated incubation temperature. This may indicate that these proteins involved in the infection process of A. salmonicida are induced by both factors. The analysis of the outer membrane vesicles (OMVs) with and without applied stresses revealed significant differences in the proteomes. OMVs were smaller and contained more cytoplasmic proteins after antibiotic treatment. After cultivation with low iron availability, several iron-regulated proteins were found in the OMVs, indicating that A. salmonicida OMVs potentially have a function in iron acquisition, as reported for other bacteria. The presence of iron-regulated transporters further indicates that OMVs obtained from ‘stressed’ bacteria might be suitable vaccine candidates that induce a protective anti-virulence immune response.
Under the influence of human activities, increased climate variability induces changes in
multiple marine environments. Especially vulnerable are the coastal ecosystems where organisms
must cope with constant extreme changes of environmental drivers, such as temperature, salinity, pH,
and oxygen content. In coastal areas, brachyuran crabs are important animals that have a high impact
on ecosystem functioning and serve as a link in food webs and pelagic-benthic coupling. Larval stages
of crabs are crucial for population persistence and dispersal. They are generally more vulnerable to
changes of environmental drivers and failure to adapt to new conditions may result in population
collapse. To analyse the effects of multiple environmental drivers on larval performance and to
elucidate interspecific and intraspecific difference, this project examined larval performance in the
European shore crab Carcinus maenas. In this study, larvae of C. maenas from three native
populations (Cádiz: Cádiz Bay, Helgoland: North Sea, Kerteminde: Baltic Sea) were reared in a
factorial design consisting of different temperature (15-24 °C) and salinity treatments (20, 25, 32.5
PSU). Results demonstrated how descriptors of larval performance (growth, physiological, and
developmental rates, and survival) were affected by combined environmental drivers. Larval
responses to temperature and salinity showed contrasting patterns and differed among native
populations originating from distant or contrasting habitats, as well as within the populations. The
highest overall performance was recorded in the Cádiz population, while the Kerteminde population
had the lowest performance in most of tested traits. The interactive effects of multiple drivers differed
among the populations. In the Cádiz and Helgoland populations, higher temperatures mitigated the
effect of lower salinity while the Kerteminde population showed a maladaptive response when
exposed to lower salinity. Differences in performance showed better locally adapted populations (e.g.
Cádiz) that could acclimate faster, have better adaptive mechanisms or stronger dispersive abilities.
Because of their wider tolerance to increased temperature and decreased salinity, interactive effects
in particular populations may favour some populations in a changing climate, especially in coastal
habitats. Variation in larval performance showed complex interactions in larval performance and
highlighted the necessity to quantify inter-population responses to climate-driven environmental
change where responses of species should not be generalised. This study emphasizes the need for
inclusion of multiple traits, drivers, and populations in experimental studies to properly characterize
performance of marine coastal animals.
Human donor milk (HDM) provides appropriate nutrition and offers protective functionsin preterm infants. The aim of the study is to examine the impact of different storage conditions onthe stability of the human breast milk peptidome. HDM was directly frozen at−80◦C or stored at−20◦C (120 h), 4◦C (6 h), or room temperature (RT for 6 or 24 h). The milk peptidome was profiledby mass spectrometry after peptide collection by ultrafiltration. Profiling of the peptidome covered3587 peptides corresponding to 212 proteins. The variance of the peptidome increased with storagetemperature and time and varied for different peptides. The highest impact was observed whensamples were stored at RT. Smaller but significant effects were still observed in samples stored at4◦C, while samples showed highest similarity to those immediately frozen at−80◦C when storedat−20◦C. Peptide structures after storage at RT for 24 h point to the increased activity of thrombinand other proteases cleaving proteins at lysine/arginine. The results point to an ongoing proteindegradation/peptide production by milk-derived proteases. They underline the need for immediatefreezing of HDM at−20◦C or−80◦C to prevent degradation of peptides and enable reproducibleinvestigation of prospectively collected samples.
Animals experience climatic variation in their natural habitats, which may lead to variation in phenotypic responses among populations through local adaptation or phenotypic plasticity. In ectotherm arthropods, the expression of thermoprotective metabolites such as free amino acids, sugars, and polyols, in response to temperature stress, may facilitate temperature tolerance by regulating cellular homeostasis. If populations experience differences in temperatures, individuals may exhibit population-specific metabolite profiles through differential accumulation of metabolites that facilitate thermal tolerance. Such thermoprotective metabolites may originate from the animals themselves or from their associated microbiome, and hence microbial symbionts may contribute to shape the thermal niche of their host. The social spider Stegodyphus dumicola has extremely low genetic diversity, yet it occupies a relatively broad temperature range occurring across multiple climate zones in Southern Africa. We investigated whether the metabolome, including thermoprotective metabolites, differs between populations, and whether population genetic structure or the spider microbiome may explain potential differences. To address these questions, we assessed metabolite profiles, phylogenetic relationships, and microbiomes in three natural populations along a temperature gradient. The spider microbiomes in three genetically distinct populations of S. dumicola showed no significant population-specific pattern, and none of its dominating genera (Borrelia, Diplorickettsia, and Mycoplasma) are known to facilitate thermal tolerance in hosts. These results do not support a role of the microbiome in shaping the thermal niche of S. dumicola. Metabolite profiles of the three spider populations were significantly different. The variation was driven by multiple metabolites that can be linked to temperature stress (e.g., lactate, succinate, or xanthine) and thermal tolerance (e.g., polyols, trehalose, or glycerol): these metabolites had higher relative abundance in spiders from the hottest geographic region. These distinct metabolite profiles are consistent with a potential role of the metabolome in temperature response.