The mouse homolog of the human amyloid beta protein (AD-AP) gene is located on the distal end of mouse chromosome 16: further extension of the homology between human chromosome 21 and mouse chromosome 16

The human amyloid beta protein is the major constituent of the brain amyloid plaques found in Alzheimer disease. The gene that encodes this protein is located on chromosome 21, and individuals with Down syndrome (trisomy 21) also exhibit an early onset form of Alzheimer disease. We have used the cloned human amyloid beta protein gene and a panel of somatic cell hybrids to map the location of the mouse homolog of this gene. We report here that the mouse gene is located on chromosome 16 within the region 16C3----ter, in common with three other genes which map within the Down syndrome region of human chromosome 21.     

A catalogue of some ecuadorean fermented beverages,with notes on their microflora

Summary A catalogue of indigenous fermented beverages produced by different ethnic groups in Ecuador has been compiled and the microflora of selected examples examined. A diversity of fermentation substrates was encountered depending on the climatic zone. The fermentations are typicallyLactobacillus spp.—yeast fermentations except for one which includes a mould fermentation by a mixed starter ofMoniha sitophila, Rhizopus stolonifer and aFusarium sp. A discussion is made of the role of these beverages in the human ecology of certain regions.

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Resumen Se ha confeccionado un catálogo de bebidas indígenas ecuatorianas producidas por distintos grupos étnicos, examinándose la microflora de algunos ejemplos seleccionados. Las fermentaciones son generalmente del tipoLactobacillus sp.—levaduras, excepto en un caso que incluye una fermentación fúngica iniciada de forma mixta porM. sitophila, R. stolonifer y unFusarium sp. Se discute el papel de estas bebidas en la ecologia humana de ciertas regiones.

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Résumé Un catalogue des boissons fermentées indigènes produites par divers groupes ethniques de l'Equateur a été compilé et les micro-flores des exemples sélectionnés ont été éxaminés. Les substrats de fermentation varient d'une région climatique à l'autre. Les fermentations sont généralement du typeLactobacillus sp — levures, sauf dans un cas qui comporte une fermentation par des moisissures, avec un mélange initial deMoniha sitophila, Rhizopus stolonifer et une espèce deFusarium. Le rôle de ces boissons dans l'écologie humaine de certaines régions est discuté.

     

Measurement variability in DNA flow cytometry of replicate samples

A Bladder Cancer Flow Cytometry Network study has been carried out aimed at identification of the sources of inter- and intralaboratory variability. Replicate "cocktail" samples containing a mixture of peripheral blood lymphocytes and an aneuploid cell line and samples of peripheral blood lymphocytes serving as a DNA reference standard were distributed to five network laboratories. The samples were stained for DNA using propidium iodide, with each laboratory using its own staining protocol. Sets of these samples were analyzed by flow cytometry to obtain cellular DNA distributions. DNA index and hyperdiploid fraction were calculated for each histogram using an automated technique. Results were evaluated by analysis of variance to identify sources of variability. Three important sources of variation were found that affect flow cytometry in general and- the transportability of flow cytometry results to routine clinical use in particular. The significant variation among laboratories that is constant across time most probably represents stable differences in instrumentation, instrument set-up, and laboratory techniques. This variation can be compensated for, if it is known and stable, to develop transportable classification criteria. The second type of variation, termed the interaction component, represents differences among laboratories that are not constant across time. Sources of this variation include inconsistency in sample preparation, staining, and analysis. The elimination of this type of variation is required for meaningful comparison of data within and among laboratories and the creation of interlaboratory data-bases. The third type of variation represents pure measurement variability and affects the sensitivity of the technique.     

Isolation and characterization of folded fragments released by Staphylococcal aureus proteinase from the non-histone chromosomal protein HMG-1

HMG-1 was isolated from newborn calf thymus without exposure to overt denaturing conditions. The purified protein was digested under several solvent conditions with the proteinase (endoproteinase GluC) from Staphylococcus aureus strain V8. We found that the preferred site of attack by the enzyme on HMG-1 was influenced markedly by ionic strength and temperature. In 0.35 M NaCl/50 mM Tris-phosphate (pH 7.8) at 37 degrees C, cleavage near the junction between the A and B domains is predominant, as previously reported by Carballo et al. (EMBO J. 2 (1983) 1759-1764). However, in 50 mM Tris-phosphate (pH 7.8) lacking NaCl and at 0 degrees C, cleavage between the B and C domains strongly predominates. Three major products of the digestions were purified and characterized. The fragment consisting of domains B and C was found by circular dichroism to contain a substantial amount of helix. This re-emphasizes the importance of avoiding overt denaturing conditions when working with members of the HMG-1 family.     

DoesAgapetus fuscipes cultivate algae in its case?

The presence of algae within the cases ofAgapetus fuscipes was investigated. Cases recognised as dirty or clean with the naked eye had more and less algal growth, respectively. Larvae in the former survived significantly longer when starved in the laboratory. It is suggested that the presence of algae within the cases would be of ecological advantage during periods of flood.     

Identification of psychrotrophic pseudomonads from goats' milk by computer-assisted analysis of carbon source assimilation data

The results of carbon source assimilation tests on a group of psychrotrophic pseudomonas were compared with published data for established Pseudomonas taxa, using computer-assisted numerical taxonomic analysis and a modified diagnostic computer program. Several phenons were not grouped at the biovar level by numerical taxonomic analysis. Identification of strains by the diagnostic program revealed heterogeneity among those in the unassigned phenons, and supported a continuum concept among the fluorescent pseudomonads.