The lantibiotic mersacidin is a strong inducer of the cell wall stress response of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

Background  

The lantibiotic mersacidin is an antimicrobial peptide of 20 amino acids that is ribosomally produced by Bacillus sp. strain HIL Y-85,54728. Mersacidin acts by complexing the sugar phosphate head group of the peptidoglycan precursor lipid II, thereby inhibiting the transglycosylation reaction of peptidoglycan biosynthesis.     

Untersuchungen über spezifische Organe niederer Sinne bei rhabdocoelen Turbellarien

Ohne ZusammenfassungDissertation bei der Philosophischen Fakultät der Albertus-Universität Königsberg i. Pr.     

The effect of oxygen partial pressure in bioreactors on cell proliferation and subsequent differentiation of somatic embryos of Cyclamen persicum

The effect of the relative oxygen partial pressure (pO₂) in bioreactors on cell proliferation and subsequent differentiation of somatic embryos from suspension cultures of Cyclamen persicum Mill. was investigated. The growth rate of cell line 3738-VIII in growth-regulator containing medium in bioreactors at 5% pO₂ was slightly reduced in comparison to 10% and 20% pO₂. Cultures growing at 40% pO₂ had a lower growth rate, a markedly reduced cell viability and showed a decrease of the medium pH to 3.5. Because a pH-control with a setpoint of 3.3 caused cell death within 4 days, it was assumed, that the reason for the poor cell proliferation and viability in the cultures at 40% pO₂ was an effect of medium acidification rather than of the high O₂ partial pressure. A significantly higher number of germinating embryos was obtained from the cultures grown at 40% pO₂ than from those grown in flasks or in bioreactors at 5%, 10% and 20% pO₂. These results were specific for cell line 3738-VIII. Another cell line, 3736-12, did not show marked differences in cell proliferation, viability, pH or subsequent regeneration of somatic embryos when grown at different O₂ partial pressures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of porcine gastrin releasing peptide on anterior pituitary hormone release

The effect of porcine gastrin releasing peptide (GRP), a heptacosapeptide with potent gastrin releasing activity which has recently been isolated from porcine non-antral gastric tissue, on pituitary function was investigated in the rat. Graded doses of synthetic porcine GRP were injected intravenously and the animals were killed at various intervals after injection. Growth hormones, LH, FSH, and TSH were measured in serum by specific radioimmunoassays. GRP had no significant effect on growth hormone or FSH serum concentrations at any dose or sampling time studied. In contrast, the heptacosapeptide significantly stimulated LH and suppressed TSH secretion in a dose-related fashion. Since there are striking structural similarities between GRP and bombesin, a tetradecapeptide from amphibian skin which shows amino acid homology with the C-terminal region of GRP, GRP may be the mammalian counterpart of bombesin.     

Loss of OMA1 delays neurodegeneration by preventing stress-induced OPA1 processing in mitochondria

Proteolytic cleavage of the dynamin-like guanosine triphosphatase OPA1 in mitochondria is emerging as a central regulatory hub that determines mitochondrial morphology under stress and in disease. Stress-induced OPA1 processing by OMA1 triggersmitochondrial fragmentation, which is associated with mitophagy and apoptosis in vitro. Here, we identify OMA1 as a critical regulator of neuronal survival in vivo and demonstrate that stress-induced OPA1 processing by OMA1 promotes neuronal death and neuroinflammatory responses. Using mice lacking prohibitin membrane scaffolds as a model of neurodegeneration, we demonstrate that additional ablation of Oma1 delays neuronal loss and prolongs lifespan. This is accompanied by the accumulation of fusion-active, long OPA1 forms, which stabilize the mitochondrial genome but do not preserve mitochondrial cristae or respiratory chain supercomplex assembly in prohibitin-depleted neurons. Thus, long OPA1 forms can promote neuronal survival independently of cristae shape, whereas stress-induced OMA1 activation and OPA1 cleavage limit mitochondrial fusion and promote neuronal death.     

Reproduction is adapted to survival characteristics across geographically isolated medfly populations

We propose the hypothesis that individual longitudinal trajectories of fertility are closely coupled to varying survival schedules across geographically isolated populations of the same species, in such a way that peak reproduction takes place before substantial increases in mortality are observed. This reproductive adaptation hypothesis is investigated for medflies through a statistical analysis of biodemographic data that were obtained for female medflies from six geographically far apart regions. The following results support the hypothesis: (i) both survival and reproductive schedules differ substantially between these populations, where early peaks and subsequently fast declining reproduction are observed for short-lived and protracted reproductive schedules for long-lived flies; (ii) when statistically adjusting reproduction for the observed differences in survival, the differences in reproductive schedules largely vanish, and thus the observed differences in fertility across the populations can be explained by differences in population-specific longevity; and (iii) specific survival patterns of the medflies belonging to a specific population predict the individual reproductive schedule for the flies in this population. The analysis is based on innovative statistical tools from functional data analysis. Our findings are consistent with an adaptive mechanism whereby trajectories of fertility evolve in response to specific constraints inherent in the population survival schedules.     

Bacterial induction and inhibition of a fast mecrotic response in Gracilaria conferta (Rhodophyta)

Of 45 bacterial isolates from healthy tips of Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann, 29% were identified as ‘conditional inducers’ of an apical necrosis. That is, the isolates induced necrotic tips in G. conferta within 16 h after elimination of most of the resident microflora from the alga. Several disinfectants and antibiotics were screened for their ability to induce algal susceptibility to the bacteria and to suppress uncontrolled appearance of tip necrosis. Treatment with 100 mg L^-1 Cefotaxim + 100 mg L^-1Vancomycin over three days was the least damaging and most efficient. Tip necrosis was related to isolates of the Corynebacterium-Arthrobacter-group and to the Flavobacterium-Cytophaga-group. The damaging effect occurred due to the bacterial excretion of active agents and was not correlated with acapability to degrade agar. The damaging influence of four Cytophaga-likestrains was inhibited by 20 of 40 isolates. This protective effect was caused by very different organisms. In five of six cases examined further, the effect was not cellbound, but due to the excretion of agents. These were not antimicrobially active, but inactivated necrosis-inducing excretions. These results indicate that epiphytic bacterial degradation or inactivation of damaging agents is a protecting factor in Gracilaria, which prevents the alga from being harmed by epiphytes. This revised version was published online in August 2006 with corrections to the Cover Date.