Das Wirken von Otto Jesse für die Erforschung der Hochatmosphäre

Ohne Zusammenfassung Vorgelegt von S. Flügge     

Dynamin-like protein encoded by the Drosophila shibire gene associated with vesicular traffic.

Temperature-sensitive paralysis is the most striking defect of adult Drosophila carrying the shibire mutation. This is believed to be due to a reversible block of endocytosis, which prevents membrane cycling and thus depletes synaptic vesicles. The shibire mutation also affects many tissues outside the nervous system. We have now mapped and characterized the shibire gene. A 275-kilobase yeast artificial chromosome was subcloned into cosmids, among which the gene was then located by analysing with restriction-fragment length polymorphisms. A 15-kilobase fragment of wild-type DNA rescues the mutant phenotype and the sequence of two mutant alleles show differences with wild type, demonstrating that we have isolated the shibire gene. The gene encodes a protein that is highly similar to rat dynamin, 69% of the amino-acid sequence is identical. Dynamin is a GTP-driven mechanochemical enzyme related to mammalian mx-proteins and to the yeast vps 1 gene product. Because the shibire gene product and dynamin have extensive similarity, we propose that they are cognate homologues. Dynamin causes microtubules to slide along each other in vitro and in extracts it is associated with a distinct, but so far uncharacterized, membrane fraction. In light of the shibire phenotype, we suggest that these proteins provide the motor for vesicular transport during endocytosis.     

Class I and class II ribonuclease H activities inCrithidia fasciculata (protozoa)

Summary The protozoanCrithidia fasciculata contains two different ribonuclease H activities. These enzymes display similar physical and biochemical characteristics to their homologues in higher eukaryotes, for instance calf thymus class I and class II ribonuclease H. Class I ribonuclease H of lower and higher eukaryotes can be activated by Mg²⁺- and Mn²⁺- ions. However, the presence of Mn²⁺-ions is inhibitory for the Mg²⁺-dependent class II ribonuclease H activity ofCrithidia fasciculata and calf thymus. The protozoan class I-homologue enzyme appears to be serologically related to the class I ribonuclease H of calf thymus.     

Molecular machinery mediating vesicle budding,docking and fusion

A general machinery buds and fuses transport vesicles which connect intracellular compartments with each other and allow communication with the extracellular environment. Cytoplasmic coat proteins deform membranes to bud vesicles and interact directly or indirectly with cargo molecules. Compartment-specific SNAREs (SNAP receptors) on vesicles and target membranes dock vesicles and provide a scaffolding for the general fusion machinery to initiate lipid bilayer fusion.     

Diagnostic value of human cytomegalovirus DNA PCR regarding different clinical specimens

Conclusions In transplant recipients, a positive HCMV PCR in PBLs is a sign of the possible development of HCMV disease which should be confirmed by further diagnostic approaches. However, detection of HCMV DNA in the CSF appears to be a specific marker of pathological processes, exemplified in a case of HCMV encephalitis.     

Observation of a pairing pseudogap in a two-dimensional Fermi gas

Pairing of fermions is ubiquitous in nature, underlying many phenomena. Examples include superconductivity, superfluidity of (3)He, the anomalous rotation of neutron stars, and the crossover between Bose-Einstein condensation of dimers and the BCS (Bardeen, Cooper and Schrieffer) regime in strongly interacting Fermi gases. When confined to two dimensions, interacting many-body systems show even more subtle effects, many of which are not understood at a fundamental level. Most striking is the (as yet unexplained) phenomenon of high-temperature superconductivity in copper oxides, which is intimately related to the two-dimensional geometry of the crystal structure. In particular, it is not understood how the many-body pairing is established at high temperature, and whether it precedes superconductivity. Here we report the observation of a many-body pairing gap above the superfluid transition temperature in a harmonically trapped, two-dimensional atomic Fermi gas in the regime of strong coupling. Our measurements of the spectral function of the gas are performed using momentum-resolved photoemission spectroscopy, analogous to angle-resolved photoemission spectroscopy in the solid state. Our observations mark a significant step in the emulation of layered two-dimensional strongly correlated superconductors using ultracold atomic gases.