The inhibition of pancreas deoxyribonuclease

The action of inhibitors on the enzymic degradation of deoxyribonucleic acid and deoxyribonucleohistone by pancreatic deoxyribonuclease has been studied. The results show that the inhibitors may be divided broadly into two classes, namely those which remove the activating magnesium ion, and those which directly interact with the enzyme protein. Active inhibitors prevent both stages (i.e. depolymerisation and hydrolysis) of the degradation of the deoxyribonucleic acid.The products which result from the reaction of nitrogen mustards with deoxyribonucleohistone are partially resistant to the action of deoxyribonuclease. Pre-treatment of deoxyribonucleohistone with other mitotic inhibitors has no effect upon its subsequent degradation with deoxyribonuclease.     

Sind die „Cytoplasmakugeln“ vonDelphinium X-Körper?

Zusammenfassung Die von Scharinger in den Epidermiszellen vonDelphinium cultorum Voss aufgefundenen Cytoplasmakugeln verhalten sich fluoreszenzoptisch in gleicher Weise wie die von Reiter beschriebenen X-bodies vonAichryson. Dies spricht dafür, da\ die Cytoplasmakugeln' vonDelphinium Virus-Einschlu\körper sind.     

The wheat durable,multipathogen resistance gene Lr34 confers partial blast resistance in rice

The wheat gene Lr34 confers durable and partial field resistance against the obligate biotrophic, pathogenic rust fungi and powdery mildew in adult wheat plants. The resistant Lr34 allele evolved after wheat domestication through two gain‐of‐function mutations in an ATP‐binding cassette transporter gene. An Lr34‐like fungal disease resistance with a similar broad‐spectrum specificity and durability has not been described in other cereals. Here, we transformed the resistant Lr34 allele into the japonica rice cultivar Nipponbare. Transgenic rice plants expressing Lr34 showed increased resistance against multiple isolates of the hemibiotrophic pathogen Magnaporthe oryzae, the causal agent of rice blast disease. Host cell invasion during the biotrophic growth phase of rice blast was delayed in Lr34‐expressing rice plants, resulting in smaller necrotic lesions on leaves. Lines with Lr34 also developed a typical, senescence‐based leaf tip necrosis (LTN) phenotype. Development of LTN during early seedling growth had a negative impact on formation of axillary shoots and spikelets in some transgenic lines. One transgenic line developed LTN only at adult plant stage which was correlated with lower Lr34 expression levels at seedling stage. This line showed normal tiller formation and more importantly, disease resistance in this particular line was not compromised. Interestingly, Lr34 in rice is effective against a hemibiotrophic pathogen with a lifestyle and infection strategy that is different from obligate biotrophic rusts and mildew fungi. Lr34 might therefore be used as a source in rice breeding to improve broad‐spectrum disease resistance against the most devastating fungal disease of rice.     

Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth

The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm’s trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains.     

The serum dependence of the occurrence of N-glycolylneuraminic acid in HeLa cells

The occurrence of N-glycolylneuraminic acid in HeLa cells is shown to be due to the calf serum added to the growth medium, and not to their cancerous nature. When Hela cells are grown with human serum as supplement, only N-acetylneuraminic acid can be found. The ganglioside composition of these cells is also reported.     

Viruskristalle in Nelken

Zusammenfassung Die äußeren Symptome der verschiedenen Viroseu vonDianthus caryophyllus sind oft gering, ja sie können sogar ganz fehlen. Für die Diagnose gewinnt daher die Feststellung innerer Symptome, nämlich des Vorkommens von Zelleinschlußkörpern besonderes Interesse. In allen daraufhin untersuchten Gartennelken ließen sich stets sowohl amorphe x-Körper als auch kristalline Einschlüsse auffinden. Die Kristalle waren von besonderer Mannigfaltigkeit, besonders gut ausgebildet waren hexagonale prismatische und tetraedrische; die letzteren stellen eine sonst ungewöhnliche Form von Viruseinschlußkörpern dar. Daß es sich wirklich um Viruseiweißkristalle handelt, wurde durch den positiven Ausfall von Übertragungsversuchen erwiesen.Dem Andenken meines verehrten Lehrers Prof. Dr. Friedl Weber widme ich diese Arbeit.     

Genetic structure, habitat fragmentation and bottlenecks in Danish bank voles (Clethrionomys glareolus)

Tissue-samples from 161 bank voles (Clethrionomys glareolus) collected in three forests (five sampling localities) situated in eastern Jutland (Denmark) were analysed by nine microsatellite loci. The genetic diversity found within the populations was high (H_e=0.753–0.806).Bank voles have specific habitat requirements favouring woodlots, hedgerows and deciduous forests as their prime living area. Hence, a natural or human-induced fragmentation of the forest may cause a sub-structuring of the populations and thereby a restriction of dispersal among populations. The sub-structuring indicated by the observed significant genetic differentiation among the five geographically distinct localities (F_st =0.033, P<0.05) could either result from habitat fragmentation or a combination of home range behaviour and different tree composition in the forests. A road situated between two adjacent forests was not found to exert any barrier effect to the gene flow of bank voles. In one out of five localities investigated, genetic evidence for a recent bottleneck-like situation was found. Bank voles are known to exhibit sometimes huge density fluctuations not only from year to year but also from season to season. The bottleneck-like situation found could therefore be due to the low number of individuals during the low-density phase.