The microaerophily and photosensitivity of Propionibacterium acnes

E. MARTIN GRIBBON, J.G. SHOESMITH, W.J. CUNLIFFE AND K.T. HOLLAND. 1994. The effect of oxygen on the in vitro propagation of Propionibacterium acnes was investigated under defined culture conditions. This micro-organism is the predominant bacterial resident within the pilosebaceous follicles of sebum-rich areas of human skin. The organism was grown in continuous culture in defined synthetic medium with glucose as the main carbon-energy source at various air saturation concentrations and in the presence and absence of light. Steady state continuous cultures were achieved at very low oxygen tensions in the presence of light, and at higher levels of oxygen when non-illuminated. Culture biomass yields were higher than those of anaerobic cultures. Bacterial cells were inactivated in the presence of light at high oxygen concentrations because of photosensitization reactions involving excess oxygen and microbial porphyrin species.     

Distribution of vasoactive intestinal peptide-like immunoreactivity in the taste organs of teleost fish and frog

Summary Using immunohistochemistry, vasoactive intestinal peptide (VIP) was visualized in taste bud cells of the carp, Cyprinus carpio, and the European catfish, Silurus glanis, by means of light and electron microscopy. Intracellular membrane systems, presumably smooth endoplasmic reticulum, of light (sensory) cells, but not of dark (supporting) cells and basal cells, were densely labelled with antibody. In the frog (four species: Rana temporaria, R. ridibunda, R. arvalis, R. pipiens), taste bud cells did not label. However, the dense basal nerve fibre plexus, some subepithelial ganglionic cells, but no ascending intragemmal fibres, were immunoreactive. In fish, the results support evidence that VIP is involved in the modulation of taste transduction at the level of receptor cells. In the frog, an indirect, possibly vasodilatatory effect on taste perception may be considered.     

Allosteric-type control of synaptobrevin cleavage by protect tetanus toxin light chain

The light chain of tetanus neurotoxin (TeNT L chain)has been shown to be endowed with zinc endopeptidaseactivity, selectively directed towards theGln⁷⁶–Phe⁷⁷ bond of synaptobrevin, avesicle-associated membrane protein criticallyinvolved in neuroexocytosis. In previous reports,truncations at the NH₂- and COOH-terminus ofsynaptobrevin have shown that the sequence 39–88 ofsynaptobrevin is the minimum substrate of TeNT,suggesting either the requirement of a well-definedthree-dimensional structure of synaptobrevin or a rolein the mechanism of substrate hydrolysis for residuesdistal from the cleavage site. In this study, theaddition of NH₂- and COOH-terminal peptides ofsynaptobrevin, S 27–55 (S₁) and S 82–93(S₂), to the synaptobrevin fragment S 56–81allowed the cleavage of this latter peptide by TeNT tooccur. This appears to result from an activationprocess mediated by the simultaneous binding ofS₁ and S₂ with complementary sites presenton TeNT as shown by surface plasmon resonanceexperiments. All these results favor anexosite-controlled hydrolysis of synaptobrevin by TeNTprobably involving a conformational change of thetoxin. This could account for the high degree ofsubstrate specificity of TeNT and, probably, botulinumneurotoxins.     

Grenzen der Kompensation: Energiebudgets von Ringelg?nsen (Branta b. bernicla) — die Wirkung von St?rreizen

Zusammenfassung Der Einfluß von Störreizen auf das Energiebudget von Ringelgänsen wurde im Frühjahr 1991 in zwei Vorland-Salzwiesen des Nationalparks Schleswig-Holsteinisches Wattenmeer vergleichend untersucht. Die Häufigkeit störreizbedingter Reaktionen der Gänse (Störreizhäufigkeit) wurde als Index für die anthropogene Beeinflussung der Gebiete herangezogen. Die Beeinflussung war in Westerhever mit 1,5±0,7 Reaktionen/h signifikant größer als vor dem Norderheverkoog (1,0±0,6 Reaktionen/h). Mit zunehmender Aktivitätszeit wurde in beiden Gebieten im Verlauf des Frühjahres mehr umsetzbare Energie aufgenommen. In Westerhever haben die Gänse im Vergleich zu denen vor dem Norderheverkoog mit Ausnahme des Mai jeweils mehr umsetzbare Energie aufgenommen. Die energetischen Kosten (DEE) der Gänse wurden anhand der Zeit-Energie-Budget Methode und über die gemessene Körpermasseentwicklung von Fänglingen berechnet. Beide Methoden erzielten vergleichbare Ergebnisse; die Unterschiede betrugen je nach Gebiet 0,4 bis 4,5 %. In Westerhever verzeichneten die Gänse im Vergleich zu denen vor dem Norderheverkoog im Monatsmittel höhere energetische Kosten. Aus dem budgetierten Energieüberschuß (E) wurde die theoretisch mögliche Reservestoffanlagerung (Änderung der Körpermasse) der Gänse berechnet. In Westerhever konnten die Gänse im Verlauf des Frühjahres 357 g Körperreserven anlagern. Bei den Gänsen vor dem Norderheverkoog waren es 399 g. Der Unterschied betrug 11,7 %, war aber nicht signifikant. Anhand von Fangdaten ist bekannt, daß Ringelgänse im langjährigen Mittel Körperreserven von 380 bis 400 Gramm anlagern. Die Störreizhäufigkeit des Tages bewirkte eine signifikante Veränderung der Budgetparameter DME und DEE und E auf stündlicher Basis. In Westerhever stieg die Aufnahme an umsetzbarer Energie signifikant mit steigender Störreizhäufigkeit an. Vor dem Norderheverkoog verringerte sich diese jedoch signifikant. Die Energieaufwendungen stiegen in beiden Gebieten signifikant mit steigender Reizhäufigkeit an. Der Überschuß in der Energiebilanz der Gänse in Westerhever war an Tagen mit einer großen Störreizhäufigkeit um 8,7 % gegenüber den Tagen mit einer geringen Reizhäufigkeit verringert. Aufgrund fehlender kompensatorischer Nahrungsaufnahme war der Überschuß bei den Gänsen vor dem Norderheverkoog um maximal 27,5 % vermindert. Die Gänse in Westerhever haben störreizbedingte Zeitverluste bei der Nahrungsaufnahme und erhöhte energetische Kosten durch Verhaltensänderung und eine erhöhte Nahrungsaufnahme pro Zeit kompensiert. Aufgrund physiologischer Zwänge sind sie jedoch in dem stark vom Menschen beeinflußten Gebiet an die Grenzen ihrer Kompensationsmöglichkeit angelangt. Die errechnete Reservestoffanlagerung und auch der Jungvogelanteil im nachfolgenden Herbst waren geringer als bei den Gänsen vor dem Norderheverkoog.

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Compensatory limits: energy budgets of Brent Geese,Branta b. bernicla, the influence of human disturbance

The impact of human disturbances on the energy budget of Brent Geese,Branta b. bernicla, during spring migration was investigated in two different salt marsh areas within the national park Schleswig-Holsteinisches Wattenmeer, Germany. We used the frequency of disturbance-related reactions of the birds as an indicator of the anthropogenic influencing of the sites. The disturbance frequency was significantly higher in the Westerhever salt marsh (1,5±0,7 reactions/h) than in the Norderheverkoog area (1,0±0,6 reactions/h). Monthly activity and energy budgets of the birds were calculated from March to May, based on several simultaneous day-round field observations per month. The amount of daily metabolizable energy (DME) was calculated via dropping rate and digestability of the food. The daily energy expenditure (DEE) was calculated by means of the time-energy-budget methods and by calculations, using the bodymass changes of caught birds during spring. With both methods very similar results were obtained; they varied between 0,4 to 4,5 % per areas and month. The daily energy budget (Æ E) was calculated from DEE — DME. Due to an increasing daily activity time from March to Mai the DME increased in both areas. Compared to the Norderheverkoog area the DME of the birds in Westerhever was higher in March and April, and similar in Mai. DEE increased in both areas too and was in all months higher in Westerhever than in Norderheverkoog. The calculated bodymass changes of the birds during spring was 357 g for the birds in Westerhever and 399 g for the birds in Norderheverkoog. Bodymass measures from caught birds revealed a mean mass gain of 380 to 400 g during spring. The daily disturbance frequency caused a significant change in the budget parameters DME, DDE and E on a hourly base. In Westerhever DME/h increased, while in Norderheverkoog DME/h decreased significantly with increasing disturbance frequency. At the same time DEE/h increased in both areas significantly. As a consequence E/h was reduced at days with a high disturbance frequency; in Westerhever by 8,7 % and in Norderheverkoog by 27,5%. In the disturbed area the birds compensated the time-loss during feeding and the higher energetic costs during disturbance-related flights by a change in activity pattern and by an increased food consumption per time unit. Based on physiological constraints the birds reached their compensatory abilities. The calculated bodymass gain and the proportion of young birds in the flocks was reduced in autumn.

     

Occupational injuries,illness affect 1 in 13 Canadians.

One in every 13 Canadian workers has experienced a work-related illness or injury, federal data indicate. Occupational-health clinics in Ontario report a growing number of cases of sick-building syndrome, repetitive-strain injury, asthma and chemical exposure, as well as injuries related to the use of construction equipment. In the past the medical profession assumed that men incurred most work-related injuries, but today, says an occupational-health specialist, "work-related illness and injuries are just as likely to happen to women or to white-collar professionals."     

Methane monooxygenase mutants of Methylosinus trichosporium constructed by marker-exchange mutagenesis

Abstract Methylosinus trichosporium OB3b synthesizes a soluble cytoplasmic methane monooxygenase when grown in copper-depleted medium and a membrane-bound particulate methane monooxygenase under copper-replete conditions. The genes encoding the hydroxylase component of soluble methane monooxygenase, carried on a plasmid in Escherichia coli , were insertionally inactivated using a kanamycin cassette and transferred back into M. trichosporium by conjugation. Marker-exchange mutagenesis, via a double homologous recombination event, yielded a soluble methane monooxygenase-negative mutant which grew only on methane using the particulate methane monooxygenase during copper-replete growth conditions, thus proving that the two methane oxidation systems in this methanotroph are genetically distinct.