ATXA -dependent gene expression in Bacillus anthracis

The Bacillus anthracis toxin genes, cya, lef , and pag, can be viewed as a regulon, in which transcription of all three genes is activated in trans by the same regulatory gene, atxA, in response to the same signal, CO2. I determined that several phenotypes are associated with the atxA gene. In addition to being toxin-deficient, an atxA -null mutant grows poorly on minimal media and sporulates early compared to the parent strain. Furthermore, an atxA-null mutant has an altered 2-D gel protein profile. I used a genetic approach to find additional atxA-regulated genes. Random transcriptional lacZ fusions were generated in B. anthracis using transposon Tn 917-LTV3. Transposon-insertion libraries were screened for mutants expressing increased β-galactosidase activity in 5% CO2. Introduction of an atxA-null mutation in these mutants revealed that 79% of the CO2-regulated fusions were also atxA-dependent. DNA sequence analysis of transposon insertion sites in mutants carrying CO 2/atxA-regulated fusions revealed ten mutants harboring transposon insertions in loci distinct from the toxin genes. The majority of the tcr (toxin co-regulated) loci mapped within the pXO1 pathogenicity island. These results indicate a clear association of atxA with CO2-enhanced gene expression in B. anthracis and provide evidence that atxA regulates genes other than the structural genes for the anthrax toxin proteins. ^ Characterization of one tcr locus revealed a new regulatory gene, pagR. The pagR gene (300 nt) is located downstream of pag. pagR is cotranscribed with pag and is responsible for autogenous control of the operon. pagR also represses expression of cya and lef. Repression of toxin gene expression by pagR may be mediated by atxA. The steady state level of atxA mRNA is increased in a pagR mutant. Recombinant PagR protein purified from Escherichia coli did not specifically bind the promoter regions of pagA or atxA. An unidentified factor in B. anthracis crude extracts, however, was able to bind the atxA promoter in the absence of PagR or AtxA. These investigations increase our knowledge of virulence regulation in B. anthracis and ultimately will lead to a better understanding of anthrax disease. ^

Instrucciones para la aplicacion de la vacuna contra la fiebre car bonosa.

Mode of access: Internet.

Traité des maladies vermineuses dans les animaux /

Encuadernado con: "Traité du charbon ou anthrax dans le animaux" /par M. Chabert.

Nachweis von Milzbrand in Futtermitteln mit Hilfe der Präzipitationsmethode ...

Inaug.-diss.--Hannover, 1913.

Gibt es in fleischbeschautechnischer Hinsicht beim Schweine einen lokalen Milzbrand?

Inaug.-diss.--Leipzig, 1913.

Die Einwirkung von Formaldehydum solutum auf Milzbrand bei intravenöser Einverleibung.

Inaug.-diss.--Hannover, 1912.

Die Beeinflussung des Milzbrandbazillus durch andere Bakterienarten.

Inaug.-diss.--Hannover, 1912.

Untersuchungen über die Brauchbarkeit des Strassburger Gipsstäbchen- und Papierrösschenverfahrens zur Einsendung von Milzbrandmaterial mit besonderer Berücksichtigung des biologischen Verhastens des Milzbrandbazillus in fausenden Organen.

Inaug.-diss.--Hannover, 1912.

Le charbon des animaux et de l'homme. Leçons faites à la Faculté de médecine de Paris.

Mode of access: Internet.

Die Serodiagnose des Milzbrandes vermittels der Ascoli'schen Thermopräzipitationsmethode.

Inaug.-diss.--Hannover, 1911.

Studien über die Präzipitinreaktion nach Ascoli bei Milzbrand.

Inaug.-diss. - Hannover, 1912.

Louis Pasteur

No presente trabalho procede-se a uma descrição sobre os aspetos considerados mais relevantes relativos à vida e à obra do extraordinário cientista e humanista do século XIX – Louis Pasteur. Contextualiza-se, também, em vários pontos, a sua obra com a de outros cientistas da época, enquadrando os trabalhos por si realizados em descobertas anteriores. Abordam-se os magníficos estudos feitos no âmbito da cristalografia (que muito contribuíram para a moderna estereoquímica) e da fermentação, como um mecanismo utilizado por certos microrganismos para produzir energia na ausência de oxigénio, facto totalmente inédito na época. Explica-se como Pasteur, de uma forma inteligentíssima, conseguiu pôr fim à velha teoria da geração espontânea. Refere-se como surgiu a genial ideia da pasteurização, termo em homenagem ao grande sábio, que veio a modificar toda a indústria do vinho, da cerveja e de tantos outros alimentos, estabelecendo a importância da microbiologia na indústria alimentar. Abordam-se os estudos realizados por Pasteur sobre doenças infeciosas (a pebrina, a cólera das galinhas, o carbúnculo e a raiva), incluindo os espetaculares procedimentos que conduziram à elaboração das primeiras vacinas que ensinaram aos cientistas mais novos a fabricar outras, salvando-se tantas vidas.