syllopsis Equations were determined for the dependency of the melting temperature (TJ of DNA upon the logarithm of the sodium ion concentration, for four DNA samples of widely diflerent base compositions (eoc). The dopee of these T, versus log M equations were found to decrease with increasing Boc of the samples. An empirical equation relating T, , log M (Na+) and eoc was derived, which also accounts for merences in T, v e m s log M slopes. Data from the literature for some synthetic polynucleotides and for the crab (Cancer puguru-s) satellite poly AT are discussed in relation to the above finding. The changes in T, versus log M slopes with Boc are interpreted in terms of changes in the thermodynamic parameters A S and A H with base compwition.

SUMMARYThis paper consists of a reference list of bacterial species for which deoxyribonucleic acid base compositions are known. Culture-collection strain numbers have been included wherever possible. The compilation may also provide a basis for the inclusion of these data into species descriptions.

SUMMARY The aetiological agent of contagious equine metritis (CEM) has been investigated bacteriologically in a wide range of cultural and conventional biochemical tests, in the electron microscope, for DNA base composition (36.1 per cent GC), for susceptibility to various antimicrobial agents and antigenically by means of tube and slide agglutination tests. The organism is a fastidious, Gramnegative, non acid‐fast coccobacillus which in biochemical tests is very unreactive. In conventional tests, only the oxidase, catalase and phosphatase tests were positive. Dependance on neither X nor V factors could be demonstrated, but some stimulation of growth by X factor was observed. The organism could not be identified with any known species and even allocation to an appropriate genus was difficult. Rather than create a new genus of only one species defined mainly on negative characters, we propose the organism as a new species of the genus Haemophilus: H. equigenitalis, type strain NCTC 11184 (61717/77). RÉSUMÉ L'agent étiologique de la métrite équine contagieuse 1977 (CEM) a été l'objet de nombreuses études biochimiques; on l'a étudié au microscope électronique: on a déterminé sa composition en ADN (36,1 % GC), on a précisé sa sensibilitéà de nombreux agents anti‐microbiens, on a apprécié son comportement antigénique par des tests d'agglutination en tube et sur lame. L'organisme est un cocco bacille Gram négatif difficile à isoler et dont le comportement biochimique est peu évocateur. Pour les épreuves habituelles seuls les tests à la catalase, à l'oxydase et à la phosphatase ont été positifs. On n'a pu établir sa dépendance pour les facteurs X et V bien qu'une certaine stimulation de la croissance par le facteur X aie pu être constatée. Cet organisme n'a pu être identifiéà aucune espèce connue et même son classement dans un genre précis s'est révélé difficile. Plutôt que de créer un genre nouveau pour cette espèce isolée définie surtout par des caractères négatifs nous proposons que cette bactérie soit désignée comme une espèce nouvelle, Haemophilus equigénitalis, type souche NCTC 11184 (61717/77). ZUSAMMENFASSUNG Der aetiologisch für die ansteckende Stutenmetritis (CEM; contagiöse, equine Metritis) verantwortliche Keim wurde bakteriologisch mit einer Vielzahl kultureller und biochemischer Tests untersucht; daneben wurde er elektronenmikroskopisch studiert, seine DNS‐Zusam‐mensetzung eruiert (36.1% GC), seine Empfindlichkeit gegenüber verschiedenen antimikrobiellen Stoffen getestet und seine antigenetischen Eigenschaften in verschiedenen Agglutinationstests abgeklärt. Der Keim ist ein anspruchsvoller, gramnegativer und biochemisch sehr wenig reaktiver Coccobacillus. Unter den üblichen Tests fielen nur Oxydase, Katalase und Phosphatase positiv aus. Weder von X‐ noch V‐Faktoren besteht eine Abhängigkeit, obschon eine gewisse Wachstumsstimulation durch den X‐Faktor zu beobachten war. Der Organismus konnte mit keiner bekannten Spezies identifiziert werden und sogar seine Zuteilung zu einem Genus erwies sich als schwierig...

HighlightsBrain endothelial cells mediate detrimental actions of IL-1 in cerebral ischemia.Neuronal cholinergic IL-1R1 also mediate detrimental actions of IL-1 in brain injury.Brain endothelial IL-1 actions reduce cortical perfusion after cerebral ischemia.Ubiquitous IL-1R1 deletion does not affect injury, suggesting compensatory mechanisms.

From infrared linear dichroism studies, direct evidence is given for a new Na DNA form, which is similar to the C form of Li DNA. This C-like form in Na DNA occurs under conditions of very low NaCl content (at high relative humidity), high NaCl content (at low relative humidity), and low G + C content of the DNA (at low relative humitiy). The C form of Li DNA was originally discovered by x-ray diffraction, but has not previously been characterized by infrared spectroscopy. The C form is primarily characterized by the orientation of the O2- -O3 line of the phosphate group, which is about 48 degrees (+/-2 degrees ) with respect to the helical DNA axis and which is different from that of the B and A forms. Na DNA molecules rich in A + T may entirely or partially adopt the C form at low relative humidity. Since from infrared evidence, the C-like form is found not only in Li DNA at low relative humidity but also in Na DNA under different conditions, the C form may be biologically important. A possible role for recognition by proteins is suggested.