Visualization of bacterial flagella by video-enhanced light microscopy.

We have imaged individual flagellar filaments of Escherichia coli, a motile Streptococcus sp., and Rhizobium meliloti by video-enhanced differential interference-contrast microscopy (Nomarski DIC) and computer-based image processing. This approach has advantages over existing methods in that filaments on living cells can be seen over their entire lengths.     

Photometric elisa calibration for antibody assay

Summary The calibration of a quantitative ELISA assay for monoclonal antibodies based on a photometric measurement may be carried out using a cubic polynomial function of the logarithm of the antibody concentration, The fit is good and the error structure is well suited to the least squares fit method. The antibody concentrations are obtained from the roots of the calibration equation calculated by the cubic formulae.     

Fine needle aspiration biopsy of cystic benign lymphoepithelial lesion of the parotid gland in patients at risk for the acquired immune deficiency syndrome

Cystic benign lymphoepithelial lesion (BLL), a previously rare lesion of the parotid gland consisting of marked lymphoid hyperplasia with accompanying squamous-lined cysts, has recently been described in patients with the acquired immune deficiency syndrome (AIDS) or AIDS risk factors. Thirteen fine needle aspiration (FNA) samples of parotid gland masses from patients with AIDS (one case), AIDS risk factors (five cases) or denial of AIDS risk factors (two cases) and a histopathologic diagnosis of BLL were examined. The FNA features that correlated best with the histopathologic findings were (1) a heterogeneous lymphoid population, (2) scattered single and/or clustered foamy macrophages and (3) superficial and/or anucleated squamous cells. Most aspirates showed some combination of these three components. The differential diagnostic considerations, the clinical and radiologic correlations and the relationship of this lesion to HIV infection are discussed. Patients with parotid masses whose aspirates consist of some combination of squamous cells, lymphocytes and foamy macrophages should be questioned for possible AIDS risk factors.     

The dynamics of experimental arable weed communities under different management practices

Abstract. Weed communities, comprising 12 introduced species at constant starting densities and three species already present in the seed bank, were followed through three years of continuous winter wheat. The wheat and weeds were subjected to two treatments in a split-plot factorial design, organic contrasting with conventional fertilizer, and ploughing plus hand-roguing contrasting with minimum tillage plus herbicide. The minimum tilled plots developed in a uniform manner, and became dominated by very high densities of Anisantha sterilis. Agrostemma githago and Galium aparine also persisted in these plots at lower densities. The ploughed plots had a lower total density but a greater range of species. Stellaria media, Veronica persica and Avena fatua were the most common; other species occurred at lower densities. The major effect of fertilizer treatment was a greater initial increase by G. aparine on the organic, minimum tilled plots compared with the conventionally fertilized, minimum tilled plots. Species associated with minimum tillage were annuals with either no or a short term seed bank and autumn germination and rather predictable dynamics, whereas species that did well under ploughing were either spring germinating or had a persistent seed bank, implying greater annual variation in population size associated with weather conditions. There seemed no clear way to distinguish between those species which were abundant on the ploughed plots and those which were scarce under all conditions using readily accessible data.     

Giemsa C-banded Karyotypes of Eight Species of Alstroemeria L. and Some of Their Hybrids

Karyotype analysis of Alstroemeria angustifolia ssp. angustifolia,A. aurea, A. inodora, A. ligtu spp. ligtu, A. magnifica ssp.magnifica, A. pelegrina, A. philippii and A. psittacina usingFeulgen-staining and Giemsa C-banding techniques revealed foreach species a characteristic chromosome morphology and C-bandingpattern. These characteristics could be used to identify manyindividual chromosomes in diploid interspecific hybrids. Besidesinterspecific variation, some degree of intraspecific variationin C-banding pattern was observed within A. angustifolia ssp.angustifolia, A. aurea, A. ligtu ssp. ligtu, A. magnifica ssp.magnifica and A. philippii . All species had large chromosomes (2 n =2 x =16) and asymmetrickaryotypes. In many species the short arms of the acrocentricchromosomes were darkly stained upon Giemsa C-banding. Thesetelomeric bands seemed satellites. B-chromosomes were observedin one species, A. angustifolia ssp. angustifolia . A variablenumber of large intercalary and telomeric C-bands was presentin the Chilean species, whereas the Brazilian species showedonly small C-bands. The differences in karyotypes suggest anearly separation of the Chilean and Brazilian species, afterwhich speciation followed different evolutionary pathways. InAlstroemeria the Giemsa C-banding technique can be valuableto plant taxonomists for unravelling species relationships. Alstroemeria ; Inca lily; evolution; Giemsa C-banding; karyotype     

Effect of medicating ingredients and other additives on microflora present on swine and chicken feeds from a Manitoba mill

The occurrence of microfloral components on medicated and non-medicated swine and chicken feed pellets and crumbles, produced in a Manitoba feed mill between June 1991 and October 1992, was determined. Addition of medicates to feeds generally decreased bacterial incidence and increased that of Eurotium spp. fungi. The effect was less pronounced when copper sulphate was added to medicated swine feeds.Contribution No. 1662.     

Pilot study of the Urals population by tooth electron paramagnetic resonance dosimetry

During 1949–1956, about 76 × 10⁶ m³ of radioactive liquid waste containing a total activity of 10¹⁷ Bq was discharged into the Techa River by the first Russian industrial nuclear facility Mayak. As a consequence, the population living in the river valley received considerable internal and external radiation doses. The results of a first application of electron paramagnetic resonance (EPR) of tooth enamel for a retrospective individual dose evaluation of the residents of the Techa riverside are presented. Three main contributions to the dose absorbed in tooth enamel have been considered: external exposure mainly from the Techa River sediments, internal exposure mainly due to ⁹⁰Sr; and background radiation including all other sources of exposure except the Techa River. The teeth of 86 inhabitants of the town Kamensk-Uralskii were analysed to determine the age-dependent contribution of the background radiation to the enamel dose. For 22 residents of the middle and lower Techa riverside, measurements of the ⁹⁰Sr whole-body content and EPR measurements of the absorbed dose in enamel were used to establish a correlation between these two quantities. Finally, absorbed doses in the enamel of five residents of the upper Techa riverside were determined by the EPR method. Contributions of the background radiation and the internal ⁹⁰Sr contamination were subtracted to determine the external exposure of the residents.