160,819 research outputs found
The terminal redundant regions of bacteriophage T7 DNA: their necessity for phage production studied by the infectivity of T7 DNA after modification by various exonucleases
No full textDreiseikelmann B, Wackernagel W. The terminal redundant regions of bacteriophage T7 DNA: their necessity for phage production studied by the infectivity of T7 DNA after modification by various exonucleases. Molecular and General Genetics. 1978;159(3):321-328.Some aspects of the involvment of the terminal reduntant regions of T7 DNA on phage production have been studied by transfection experiments with T7 DNA after treatment of the molecules with [lambda] exonuclease or [lambda] exonuclease plus exonuclease I. It was found that terminal 5prime gaps between 0.08 and 6.4% of the total length did not decrease the infectivity of the molecules although such gaps cannot be filled directly by DNA polymerases. Rather, compared to fully native DNA the infectivity of gapped DNA increased up to 20 fold in rec + spheroplasts and up to 4 fold in recB spheroplasts. This indicates a protective function of the single-stranded termini against the recBC enzyme in rec + and possibly another unidentified exonuclease present also in recB. The possibility that spontaneous circularization of the gapped molecules in vivo provides protection against exonucleolytic degradation was tested by transfection with T7 DNA circularization in vitro by thermal annealing. Such molecules were separated from linear molecules by neutral sucrose gradient centrifugation. They displayed a 3 to 6 fold higher infectivity in rec + and recB compared to linear gapped molecules, which shows that T7 phage production may effectively start from circular DNA. When the 3prime single-stranded ends from gapped molecules were degraded by treatment with exonuclease I the infectivity of the molecules was largely abolished in rec + and recB as soon as 40 to 80 base pairs had been removed per end. It is concluded that the terminal regions of T7 DNA molecules are essential for phage production and that the redundancy comprises probably considerably less than 260 base pairs. The results are discussed with respect to the mode of T7 DNA replication
Length determination of the terminal redundant regions in the DNA of phage T7
No full textDreiseikelmann B, Steger U, Wackernagel W. Length determination of the terminal redundant regions in the DNA of phage T7. Molecular and General Genetics. 1980;178(1):237-240.The length of the terminal redundant regions in T7 DNA has been determined by two methods. One involved the specific labeling and isolation of the redundant DNA fragment and determination of the molecular weight by polyacrylamide gel electrophoresis. A value of 150±10 nucleotide pairs was obtained. The other determination based on a correlation of the melting temperature of the redundant region to that of whole T7 DNA confirmed the result obtained by the first method
Absence in Bacillus subtilis and Staphylococcus aureus of the sequence-specific deoxyribonucleic acid methylation that is conferred in Escherichia coli K-12 by the dam and dcm enzymes
No full textDreiseikelmann B, Wackernagel W. Absence in Bacillus subtilis and Staphylococcus aureus of the sequence-specific deoxyribonucleic acid methylation that is conferred in Escherichia coli K-12 by the dam and dcm enzymes. Journal of Bacteriology. 1981;147(1):259-261.Restriction analysis of plasmid pHV14 deoxyribonucleic acid isolated from Escherichia coli K-12, Bacillus subtilis, and Staphylococcus aureus with restriction endonucleases MboI, Sau3AI, and EcoRII was used to study the methylation of those nucleotide sequences which in E. coli contain the major portions of N6-methyladenine and 5-methylcytosine. The results showed that neither B. subtilis nor S. aureus methylates deoxyribonucleic acid at the same sites and nucleotides which are recognized and methylated by dam and dcm enzymes in E. coli K-12
Infectivity of various forms of bacteriophage T7 DNA
No full textWackernagel W, Seroka K, Dreiseikelmann B, Prell A. Infectivity of various forms of bacteriophage T7 DNA. In: Portolés A, ed. Modern trends in bacterial transformation and transfection. Amsterdam: North-Holland Publ. Co.; 1977: 185-192
Prof. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
On the epidemiology, biology and food-dependent reproduction of the feral pigeon (Columba livia)
No full textMillions of feral pigeons (Columba livia, Gmelin 1789) live in close association with the human population in our cities. They have managed to adapt extremely well to city life. The partial absence of an effective regulation by enemies and the rich food basis in urban habitats allows the development and maintenance of large feral pigeon populations. These, however, can cause various problems such as fouling with feces, and the transmission of pathogenic microorganisms and parasites to humans. While many wild-living species have a parasitic fauna comparable to that of feral pigeons, no other species lives as close to humans and offers that many possibilities of transmission. Feral pigeons breeding and roosting close to human lodgings thus pose a serious health risk, which is why many homeowners try to protect themselves by repelling the birds from their house facades, window ledges and balconies.
New pigeon proofing systems are regularly introduced onto the market, but scientific proof of efficacy and a statement regarding their use from the point of view of animal welfare is usually lacking. We therefore evaluated the effectiveness of two gel repellents on free ranging feral pigeons in an experimental pigeon loft. The gels used an alleged tactile or visual aversion of the birds, reinforced by additional sensory cues. This study concludes that both gels show a restricted, transient repellent effect, but fail to prove the claimed complete effectiveness. In addition, the adhesive effect of the gels conflicts with animal welfare concerns because gluing of plumage presents a serious risk to feral pigeons and also to other non-target birds. The repellent gels are therefore not suitable for feral pigeon management in urban areas.
Additionally, an overview of the most essential pigeon proofing systems is provided within the frame of this thesis. It discusses the advantages and disadvantages of the most widespread systems and further sets the focus on animal welfare issues. The overview points out that even initially harmless and animal friendly proofing systems might become dangerous to the birds over time if they are not regularly maintained. It further highlights how important it is to scientifically test each system before usage. Moreover, this outline supports the recommendation that each system should come with a proper installation and maintenance guide when it is introduced onto the market. If untested systems are being put to the test by unknowing end users, they might endanger the birds. Additionally, uninformed homeowners violate the animal protection law if a system harms an animal, even if this happens with no ill intent.
In a further study, we examined the effect of a sudden decrease in the natural food basis on the reproduction of a well-studied feral pigeon breeding colony. Despite the known fact that food shortage is a major source of reproductive failure in feral pigeons, it was still unclear at which phase of the reproductive cycle it reduces overall reproductive success. The findings of this study imply that the number of broods per pair decreased significantly under food reduction, while the hatching success remained more or less constant. However, a significantly greater number of nestlings died during the costly rearing phase. Results suggest that the high energy demand of the fast growing feral pigeon nestlings cannot be met under food scarcity. The decreased number of broods and the limited fledging success consequently reduce the total number of fledged young by more than half, which finally leads to a decrease in colony size.
Another negative side effect of large feral pigeon populations, maintained through the abundant anthropogenic nutritional basis in urban surroundings, is the overcrowding at breeding places. From an epidemiological point of view, these high population densities can increase the transmission of pathogenic microorganisms and parasites, such as the pigeon tick Argas reflexus. The medically and veterinary important A. reflexus usually feeds on pigeons, but if a natural host is not available, it also enters dwellings to bite humans who can respond with severe allergic reactions including anaphylactic shock. The pigeon tick is ecologically extremely successful due to certain outstanding morphological, physiological, and ethological features. Yet, until today, it was still unclear how it finds its hosts. In the main study, we tested different host stimuli, such as living nestlings as well as begging calls, body heat, smell, host breath and pigeon tick feces, under controlled laboratory conditions. Of all stimuli tested, only heat seemed to play a central role in host-finding. Subsequently, the crucial heat stimulus was tested under natural conditions within a pigeon loft. The results demonstrated that the host finding ability of A. reflexus is restricted to only a few centimeters. We concluded that this ectoparasite finds its host by random movements and recognizes it only shortly before direct contact is made. These findings are useful for the control of A. reflexus in infested apartments, both to diagnose an infestation and to perform successful monitoring after disinfestation.
The aim of this thesis was to provide important insights into the epidemiology, biology and food-dependent reproduction of the feral pigeon. With these findings we hope to contribute to the healthier coexistence of feral pigeons and humans in urban habitats
Nowe spojrzenie na planowanie architektury mieszkaniowej w afryce subsaharyjskiej
No full textThe author shares his reflections on state of art in housing and urban planning, deficiencies, expectations and possibilities in the Sahel region of Africa. He notices, that the housing problem in Africa is one of the challenges, which should be solved in order to recover life dignity of African people and secure their rights to traditional family life in acceptable conditions. The paper describes the studies on the typical dispersed urban structures and the need to foster this type of settlement structure and proposals of introduction of new on light steel frame housing system in the area of Sahel, combining the traditional way of building houses with modern technology. The particularly analysed case, is the housing problem in the Republic of Chad. The author presents the basic discussion on this topic and his architectural proposals. Unfortunately, the gap between the needs and the financial feasibility of housing construction in this area, makes this project already at the starting point extremely difficult to be realized without external subventions.Problem mieszkaniowy w Afryce jest jednym z wyzwań, które należy rozwiązać, aby Afrykanie mogli odzyskać godność życiową i zabezpieczyć swoje prawa do tradycyjnego życia rodzinnego w akceptowalnych warunkach. W artykule opisano badania nad typowymi rozproszonymi strukturami miejskimi i potrzebą wspierania tego typu struktur osadniczych oraz propozycji wprowadzenia nowego systemu konstrukcji domów, opartym na lekkim szkielecie stalowym, łączącym tradycyjny sposób budowania domów z nowoczesną technologią. Przypadkiem szczególnie analizowanym jest problem mieszkaniowy w Republice Czadu. Autor przedstawia podstawową dyskusję na ten temat i swoje propozycje architektoniczne. Niestety luka między potrzebami mieszkaniowymi w Czadzie a finansową wykonalnością budownictwa mieszkaniowego w tym obszarze sprawia, że projekt ten, już w punkcie wyjścia, jest niezwykle trudny do realizacji bez uzyskania zewnętrznych dotacji
On the biology and epidemiology of the feral pigeon (Columba livia)
No full textFeral pigeons (Columba livia, Gmelin 1789) are among the most abundant vertebrates in the urban environment of almost every city in the world. Close contacts to humans bear the risk of transmission of zoonotic pathogens and parasites. The most important of these zoopathogens is the bacterium Chlamydia psittaci, the agent of avian chlamydiosis and human psittacosis/ornithosis. Many human infections reported in the medical literature were attributed to brief and transient contacts to feral pigeons in the urban environment. The aim of the present thesis is to investigate the prevalence of C. psittaci in the feral pigeon population of Basel, to identify possible routes of transmission in the city and to propose measures for the prevention of zoonotic C. psittaci transmissions.
In a preliminary study, 47 faecal samples were collected from nest boxes in a feral pigeon loft in Basel, Switzerland. In addition 34 samples were collected from the feather dust film on the water surface of public fountains, where feral pigeons regularly bathe. All 81 samples were tested for the presence of chlamydial antigen by use of an antigen-ELISA assay. Initially the ELISA assay yielded a high proportion of positive results: 8 out of 47 (23.5 %) faecal samples and 26 out of 34 (76.5 %) of the water film samples were tested positive. However, a subsequent blocking test revealed only one true positive faecal sample, which could be confirmed by microarray. This ELISA assay was not used for further studies.
In the main study, the prevalence of C. psittaci shedding in free ranging feral pigeons living in a pigeon loft in Basel was investigated. A total of 202 individual birds were tested on four different time points between 2007 and 2009 by analysis of pharyngeal and cloacal swabs. Some of the birds could be tested repeatedly. All samples were analyzed by use of a species-specific nested PCR assay targeting the ompA gene of C. psittaci. The tested feral pigeons were shedding C. psittaci by respiratory secretions, since 9 out of 447 (2.0 %) of the pharyngeal swabs were tested positive. Furthermore, 11 out of 348 (3.2 %) of the cloacal swabs were tested positive, indicating that these birds are shedding C. psittaci in their faecal droppings. In total, C. psittaci was documented in 17 of 202 individual birds (8.4 %). The majority of the positive birds were shedding the pathogen intermittently. At present, this is the first study to test individual free-living feral pigeons repeatedly and therefore the first to prove intermittent shedding of C. psittaci in these birds. Genotyping of the positive samples by real-time PCR revealed C. psittaci genotype B in 7 of the birds, as well as a mixed infection with the genotypes A, B and E/B in one bird. A mixed infection with three different chlamydial genotypes could be documented for the first time. Seven of the birds that tested positive immigrated into the pigeon loft as adults, including the bird with the mixed infection. Thus, it could be proven how the interconnectedness of feral pigeon subpopulations favours the spread of pathogens. Additionally, 620 faecal samples from public sites in the city were analyzed. However, C. psittaci could not be detected in these faecal samples from the urban environment.
Feral pigeons on building facades, on balconies and window ledges, or in open attics pose a health risk. Avoiding attractive building structures already during building design is the best and most cost-effective way to prevent problems with feral pigeons in the future. We identified the structural parameters required to proof a building against feral pigeons. It could be demonstrated that feral pigeons are not able to pass through an outlet width of 4 cm, the respective outlet height is 5 cm, and a pigeon-safe square opening size is not exceeding 6 × 6 cm. A feral pigeon is not able to sit on a ledge if it’s width is 4 cm or smaller. The pigeon-safe angle of inclination for smooth construction materials (tinplate, glass, plastics) is 25°, for medium rough materials (wood, plane concrete) 35°, and for rough materials (sandstone, rough concrete) at least 50°. With these essential data, required to proof a building against feral pigeons, we contribute to the prevention of disease transmissions and parasite infestations due to these birds.
The low proportion of our feral pigeons in Basel, which are shedding C. psittaci, could be documented. However, C. psittaci could not be detected in faecal samples from public sites in the urban environment. The regular cleaning of streets and squares in Basel additionally contributes to public health, since potentially infectious feral pigeon faeces are removed quickly. Considering the numerous opportunities of close contacts to feral pigeons in the urban environment, a transmission of the pathogen from feral pigeons to humans can never be ruled out. Therefore, feral pigeons present a significant potential health risk
Seeing the world anew : the radical vision of Martin Waldseemüller's 1507 & 1516 world maps /
No full text9781929154470 (ISBN). 192915447X (ISBN). First edition 2012. Accompanied by 2 foldeds map in front and back pockets: 1507 map -- 1516 map.; Includes bibliographical references: pages 98-107.; Maps from pockets also available online http://nla.gov.au/nla.map-vn6254227; Original version of the 1507 map: Universalis cosmographiae secundum Ptholomaei traditionem et Americi Vespucii alioru que lustrationes. [St. Dié, France? : s.n., 1507]; Original version of the 1516 map: Carta marina, navigatoria Portugallen, navigationes atque tocius cogniti orbis terre marisque formam naturamq[u]e situs et terminos nostris temporibus recognitos et ab antiquorum traditione differentes eciam quor[um] vetusti non meminerunt auctores hec generaliter indicat / consumatum est in oppido S. Deodati compositione et digestione Martini Waldseemuller Ilacomili. [St. Dié, France? : s.n., 1516]. Prologue: In a Renaissance Vision, a Glimpse of the Modern / John W. Hessler -- "An island surrounded on all sides by sea" : The World Map, 1507 / John W. Hessler -- "Land of Cuba, part of Asia" : The Carta marina, 1516 / Chet Van Duzer -- Epilogue: A Renaissance That Resonates Still / John W. Hessler -- Notes -- Afterword / Ralph E. Ehrenberg -- About the authors -- Acknowledgments -- The Maps: The 1507 World Map, 12 sheets, with commentary -- Composite: front pocket -- The 1516 Carta marina, 13 sheets, with commentary -- Composite: back pocket
Klimat społeczny w szkole inkluzyjnej
No full textAuthor presented in this paper theoretical approach to the building of social climate in an inclusive school. The publication indicatessome tendencies and directions of changes to improve the functioning of these institutions and to implement the idea of inclusive education.Autorka przedstawiła w artykule teoretyczne ujęcie zagadnienia związanego z budowaniem klimatu społecznego w szkole inkluzyjnej. W publikacji ukazano pewne dążenia i kierunki zmian, jakich należy dokonywać w masowych szkołach, aby poprawić jakość funkcjonowania tych placówek, tak by kierowały się one ideą edukacji włączającej
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