A lytic factor associated with brucellaphage causing ‘lysis-from-without’

Résumé Des bactériophages de Brucella se sont montrés capables de provoquer une lyse extra-cellulaire, en cultures liquides deB. abortus, en présence de glycine et d'acide éthylène-diamine-tétraacétique. Des traitements au sérum anti-bactériophage, aux enzymes protéolytiques, ou la centrifugation différentielle dans le chlorure de césium n'ont pu séparer l'activité lytique de la particule infectieuse elle-même.

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This study was supported by Public Health Service research grant No. AI 06161 from the National Institute of Allergy and Infectious Diseases and by a World Health Organization research grant. The authors are grateful to Dr.D. Pratt for helpful suggestions and assistance with the density gradient centrifugation.     

1β-Hydroxylation ofd-norgestrel and norethisterone byBotryodiploadi malorum

Zusammenfassung Die mikrobiologische 1-Hydroxylierung vond-Norgestrel und Norethisteron durch den MikroorganismusBotryodiplodia malorum wird beschrieben. Ausserdem wurde 11-Hydroxynorethisteron isoliert und charakterisiert.

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Acknowledgement. The authors want to express their appreciation to Dr.H. Smith for advice and encouragement through the course of this work. We wish to thank Dr.T. Chang, Dr.C. Hetzel and Mr.C. Kuhlman for obtaining and interpreting the mass spectra and Mr.B. Hormann for NMR decoupling experiments and analytical services.     

Oxidative damages to DNA by indoor PM_(10)s: Their relationships with trace element compositions

Inrecentyears,adversehealtheffectsofinhal ableparticles(PM10)havedrawnmoreattention.Moreover,epidemiologicalstudieshavehighlighteda possiblelinkbetweentheincreasesinPM10concentra tionandtheadultmorbidityandmortality[1,2].How ever,thebiologicalmechanismoftheadverseeffects isstillunclear.Therearemanyhypothesesonthe mechanismscausingpulmonarydamagebyparticulate matters,ofwhichawidelyacceptedhypothesisis thatthebioavailabletransitionmetalsonparticlesur facemayproducefreeradicals,whichplayanimpor…     

Pollen evidence of early human activities in Erhai basin, Yunnan Province

The evidence of human activities around Erhai Lake catchment was revealed by pollen records from a sediment core in the lake, northwest Yunnan Province. The chronologic sequence based on AMS ^14C data made it possible for pollen results to compare with archaeological records and historical documents. The preliminary deforestation started from the selective clearance at about 5500 ^14C a BP, marked by the loss of vertically distributed montane forest and the expansion of second pine woodland across the catchment. The deforestation resulted in the increase of surface runoff and the enhanced erosion in the catchment. The increased herbs of pasture and crop suggested the primitive agriculture and stockbreeding in study region. With the limited human activity, as well as the suitable climatic condition, second pine forest expanded quickly, resulting in the weakened soil erosion around the basin. The strong forest clearance inferred from pollen occurred since 2160 ^14C a BP, paralleling to the first dense immigration of population, when Yeyu County was first set up around west coast of Erhai Lake, documented in historic record. The development of agriculture led to the steady enhancement of soil erosion from farming land, increasing the input of fine materials and nutrients to the lake. Moreover, the serious deforestation by human activity stressed the vulnerability in ecosystem of the landscape. The time of primary anthropologic impact recorded from pollen is earlier than that of the oldest archaeological record by 1500 a (^14C year).     

Binding activities of a repertoire of single immunoglobulin variable domains secreted from Escherichia coli

In antibodies, a heavy and a light chain variable domain, VH and VL, respectively, pack together and the hypervariable loops on each domain contribute to binding antigen. We find, however, that isolated VH domains with good antigen-binding affinities can also be prepared. Using the polymerase chain reaction, diverse libraries of VH genes were cloned from the spleen genomic DNA of mice immunized with either lysozyme or keyhole-limpet haemocyanin. From these libraries, VH domains were expressed and secreted from Escherichia coli. Binding activities were detected against both antigens, and two VH domains were characterized with affinities for lysozyme in the 20 nM range. Isolated variable domains may offer an alternative to monoclonal antibodies and serve as the key to building high-affinity human antibodies. We suggest the name 'single domain antibodies (dAbs)' for these antigen binding demands.