Unterschiede im revier- und sexualverhalten endemisch-anatolischer zahnkarpfen (pisces,cyprinodontidae)

The endemic Anatolian cyprinodonts Aphanius chantrei, A. (Kosswigichtys) asquamatus, and A. anatoliae show definite interspecific differences in their territorial and sexual behaviour under laboratory conditions. Intraspecific differences were found in the nine populations of A. anatoliae investigated.A. chantrei and Kosswigichthys show almost the same territorial behaviour. In A. anatoliae territoriality is found in three populations; the remaining six populations show no territoriality.The sexual behaviour consists of visual display elements and of elements which enable the fish to keep close contact without actually touching each other. The sequence of elements can be variable. Only two populations of A. anatoliae have retained display elements; the remaining seven populations have lost all of them.A correlation is discussed between biotope conditions and sexual behaviour. Display and territorial behaviour may have become superfluous in extreme, sulphate-containing habitats, where a lack of flora has led to a lack of spawning sites. Under changing breeding conditions the newly evolved element with fish staying close together (male underneath the female) may have replaced the former display elements.     

The β-Hemolysin and Intracellular Survival of Streptococcus agalactiae in Human Macrophages

S. agalactiae (group B streptococci, GBS) is a major microbial pathogen in human neonates and causes invasive infections in pregnant women and immunocompromised individuals. The S. agalactiae β-hemolysin is regarded as an important virulence factor for the development of invasive disease. To examine the role of β-hemolysin in the interaction with professional phagocytes, the THP-1 monocytic cell line and human granulocytes were infected with a serotype Ia S. agalactiae wild type strain and its isogenic nonhemolytic mutant. We could show that the nonhemolytic mutants were able to survive in significantly higher numbers than the hemolytic wild type strain, in THP-1 macrophage-like cells and in assays with human granulocytes. Intracellular bacterial multiplication, however, could not be observed. The hemolytic wild type strain stimulated a significantly higher release of Tumor Necrosis Factor-α than the nonhemolytic mutant in THP-1 cells, while similar levels of the chemokine Interleukin-8 were induced. In order to investigate bacterial mediators of IL-8 release in this setting, purified cell wall preparations from both strains were tested and found to exert a potent proinflammatory stimulus on THP-1 cells. In conclusion, our results indicate that the β-hemolysin has a strong influence on the intracellular survival of S. agalactiae and that a tightly controlled regulation of β-hemolysin expression is required for the successful establishment of S. agalactiae in different host niches.     

DNA helicase-mediated packaging of adeno-associated virus type 2 genomes into preformed capsids.

Helicases not only catalyse the disruption of hydrogen bonding between complementary regions of nucleic acids, but also move along nucleic acid strands in a polar fashion. Here we show that the Rep52 and Rep40 proteins of adeno-associated virus type 2 (AAV-2) are required to translocate capsid-associated, single-stranded DNA genomes into preformed empty AAV-2 capsids, and that the DNA helicase function of Rep52/40 is essential for this process. Furthermore, DNase protection experiments suggest that insertion of AAV-2 genomes proceeds from the 3' end, which correlates with the 3'-->5' processivity demonstrated for the Rep52/40 helicase. A model is proposed in which capsid-immobilized helicase complexes act as molecular motors to 'pump' single-stranded DNA across the capsid boundary.     

Recombinant human colony stimulating factor-granulocyte/macrophage and -granulocyte, but not macrophage induce the development of a respiratory burst in primary human myeloid leukemic cells in vitro

Respiratory burst develops in myeloid blast cells if they differentiate functionally along the monocytic or granulocytic lineage. Using the nitroblue tetrazolium (NBT) assay we studied the effects of recombinant human granulocyte/macrophage colony stimulating factor (rhuGM-CSF), rhuG-CSF and rhuM-CSF on development of respiratory burst activity in primary blast cells from patients with myeloid leukemia. Assessing suspension cultures containing cells from patients with acute myeloid leukemia (AML, n = 13) or myeloid-blast crisis (myBC) of chronic myeloid leukemia (CML, n = 5) it was found that the percentage of NBT positive cells was increased by at least 20% as compared to control cultures by rhuGM-CSF in 6/17 cases, by rhuG-CSF in 7/17 cases and by rhuM-CSF in 0/16 cases, representing in 'responders' a mean increase of 267% and 270% in the absolute number of NBT positive cells by rhuGM-CSF and rhuG-CSF, respectively. Morphological examination of cultured cells from 'responders', as compared to controls, showed decreased blast cell content but generally no evidence of terminal differentiation. The demonstration of Auer rods in NBT positive cells indicates that respiratory burst developed in a leukemic clone. These findings may be of physiological, pathophysiological and clinical relevance.     

Structural genes of glutamate 1-semialdehyde aminotransferase for porphyrin synthesis in a cyanobacterium and Escherichia coli

Summary In bacteria 5-aminolevulinate, the universal precursor in the biosynthesis of the porphyrin nucleus of hemes, chlorophylls and bilins is synthesised by two different pathways: in non-sulphur purple bacteria (Rhodobacter) or Rhizobium 5-aminolevulinate synthase condenses glycine and succinyl-CoA into 5-aminolevulinate as is the case in mammalian cells and yeast. In cyanobacteria, green and purple sulphur bacteria, as in chloroplasts of higher plants and algae a three step pathway converts glutamate into 5-aminolevulinate. The last step is the conversion of glutamate 1-semialdehyde into 5-aminolevulinate. Using a cDNA clone encoding glutamate 1-semialdehyde aminotransferase from barley, genes for this enzyme were cloned from Synechococcus PCC6301 and Escherichia coli and sequenced. The popC gene of E. coli, previously considered to encode 5-aminolevulinate synthase, appears to be a structural gene for glutamate 1-semialdehyde aminotransferase. Domains with identical amino acid sequences comprise 48% of the primary structure of the barley, cyanobacterial and putative E. coli glutamate 1-semialdehyde aminotransferases. The cyanobacterial and barley enzymes share 72% identical residues. The peptide containing a likely pyridoxamine phosphate binding lysine is conserved in all three protein sequences.     

No evidence for linkage of autosomal dominant proximal spinal muscular atrophies to chromosome 5q markers

Summary Two recent articles have reported the linkage of a gene for recessive spinal muscular atrophy (SMA) on the chromosome region 5q11.2–13.3. Our data show no linkage of the dominantly inherited forms of SMA to this chromosome region.     

Die Temperaturabhängigkeit des Wachstums vonPhaeocystis pouchetii (Haptophyceae) in Batchkulturen

Temperature dependent growth rates ofPhaeocystis pouchetii (Haptophyceae) were investigated in 5–1 batch cultures. The algae had been isolated from the German Wadden Sea area off Sylt. Microscopic cell counts and fluorescense measurements yielded similar results. The growth ofP. pouchetii reveals a typical optimum curve between 7 °C and 20 °C. Maximal growth rates, 3 divisions per day, were obtained at 15 °C. At 5 °C the algae cultures survived, but multiplication of the cells almost ceased. Results of the culture experiments correspond with observations made onPhaeocystis blooms at the German North Sea coast.     

Mechanism of cell-mediated cytotoxicity at the single cell level. VIII. Kinetics of lysis of target cells bound by more than one cytotoxic T lymphocyte

We measured the effects of having multiple cytotoxic T lymphocytes (CTL) bound to one target cell by using the single-cell cytotoxicity in agarose assay. We found that even though there is variability in the time at which individual target cells are lysed, we can identify a general trend: the mean rate of lysis increases with the number of CTL bound per target cell, reaching a maximum when the CTL-target cell ratio is three. Combining a quantitative model for the rate of lethal hitting in multicellular conjugates with a multi-event model for the rate of target cell disintegration, we developed a new multistage kinetic model for predicting the rate of target cell lysis in multiple lymphocyte-target cell conjugates. The variability in the time at which target cells are hit and the variability in the time until they disintegrate are incorporated into the model. By analyzing our measured data in the context of the multistage kinetic model, we were able to estimate via nonlinear least squares regression the target cell disintegration rate, but not the lethal hitting rate. Lethal hitting appeared to be too fast, when compared with disintegration, to significantly affect the time of target cell lysis. By using previously determined values of the lethal hitting rate for single lymphocyte-target cell conjugates and by postulating that lymphocytes act independently of each other in delivering lethal hits, we were able to estimate the rate at which target cells are hit in multiple-lymphocyte single target cell conjugates. By using this estimate of the lethal hitting rate and the regression estimate of the disintegration rate, the multistage kinetic model gave a quantitative fit to our data. From this analysis, we found that the rate at which a target cell disintegrates after being lethally hit increases with the number of CTL per conjugate. This result is quite surprising, because once the first hit has been received, a target cell can disintegrate in a killer cell-independent manner. Under the conditions of our experiment, it appears as if target cell disintegration is not killer cell-independent. Furthermore, our analysis of the time course of target cell disintegration suggests that the process is not governed by simple first order kinetics, but rather by a more complex multistep mechanism.