A method for the harvest,culture, and characterization of human adult atrial myocardial cells: Correlation with age of donor

Summary Myocardial cell culture methods are now well established for animal and fetal human tissue. We present here a method for harvesting and culturing adult human atrial myocardiocytes. Cells are obtained from fresh atrial tissue normally discarded after being removed to cannulate the right atrium during open heart surgery. The atrial tissue is minced and then digested using collagenase. The single cell suspension is initially cultured in serum-containing growth medium, then transferred to defined medium, selective for myocardial cell growth. The cells are characterized by immunoperoxidase stains and transmission electron microscopy. The cultured cells stain positive for myoglobin, whereas control cultured fibroblasts and endothelial cells do not. Electron microscopy shows the presence of numerous myofibrils, Z-bodies, pleomorphic mitochondria, and secretory granules. The chronological age of the donor was an important factor in culturing the adult tissue, the younger tissue correlated with a higher success rate. This method provides a means for in vitro study of human adult myocardial cells and provides guidelines for appropriate atrial tissue to use.     

The exosome of Trypanosoma brucei.

The yeast exosome is a complex of at least 10 essential 3'-5' riboexonucleases which is involved in 3'-processing of many RNA species. An exosome-like complex has been found or predicted to exist in other eukaryotes but not in Escherichia coli. The unicellular parasite Trypanosoma brucei diverged very early in eukaryotic evolution. We show here that T.brucei contains at least eight exosome subunit homologs, but only a subset of these associate in a complex. Accordingly, the T.brucei exosome is smaller than that of yeast. Both free and complex-associated homologs are essential for cell viability and are involved in 5.8S rRNA maturation. We suggest that the exosome was present in primitive eukaryotes, and became increasingly complex during subsequent evolution.     

Genetic analysis of murine strains C57BL/6J and C3H/HeJ to confirm the map position ofAth-1, a gene determining atherosclerosis susceptibility

Previous results suggested that strains C57BL/6J and C3H/HeJ differed in a single gene for atherosclerosis susceptibility, calledAth-1. Based on data from recombinant inbred strainsAth-1 was tentatively assigned to chromosome 1 linked toAlp-2. In this report, a cross between C57BL/6 and C3H/HeJ was carried out in order to test whether the tentative map position was correct. Parental strains and F₁ and F₂ progeny were examined. Susceptible alleles ofAth-1, found in C57BL/6, are associated with relatively low levels of high-density lipoprotein (HDL)-cholesterol in animals fed an atherogenic diet; resistant alleles ofAth-1 are associated with relatively high levels of HDL-cholesterol. F₁ progeny have HDL levels that are intermediate between these of the two parental strains. Among the F₂ progeny,Alp-2 andAth-1 cosegregated, providing confirmatory evidence thatAth-1 is linked toAlp-2 on chromosome 1. Three mice recombinant forAlp-2 andAth-1 were found among the 60 chromosomes tested, giving an estimated map distance between these two genes of 5.0±2.8 (SE) cM. The phenotypic characteristics ofAth-1 resemble a genetic trait in humans, hyperalphalipoproteinemia, which is characterized by elevated levels of HDL-cholesterol, reduced risk of heart disease, and increased longevity.This work was supported by Grant HL-32087 from the Heart, Lung, and Blood Institute, National Institutes of Health, Grant 1858 from the Council for Tobacco Research, Grant 86-1387 from the American Heart Association with funds contributed in part by the Alameda, Orange, and Santa Barbara County Chapters, and Grants 85-N132A and 85-N136A from the California Affiliate of the American Heart Association.     

Quantitative comparison of the laboratory and field competitiveness of Rhizobium leguminosarum biovar phaseoli

Rhizobium leguminosarum bv. phaseoli KIM5s outcompeted strain CE3 in bean (Phaseolus vulgaris L.) root nodulation when plants were grown at any of three field sites, each with a different soil type and indigenous population, or in the laboratory in a sterilized sand, a sterilized peat-vermiculite mixture, or a nonsterile field soil. A mathematical model describing nodulation competitiveness was empirically derived to evaluate the relative competitiveness of the two strains under these conditions. This model relates the proportional representation of the two strains in the inoculum to the proportional representation of nodules occupied by each strain or both strains and provides a measure of competitiveness, which is referred to as the competitiveness index. Statistical comparisons of competitiveness indices showed that the relative competitiveness of KIM5s and CE3 remained constant when the two strains were applied in a constant ratio over a range of inoculum concentrations, from 10(3) to 10(7) cells per seed, and when they were applied in various ratios to six P. vulgaris cultivars. Furthermore, the relative competitiveness of KIM5s and CE3 in the laboratory did not differ significantly from their relative competitiveness at the three field sites studied. Thus, a study of the basis for nodulation competitiveness of KIM5s and CE3 in the laboratory has the potential to provide an understanding of competitiveness both in the laboratory and in the field.     

Variation of tandem repeats in the developmentally regulated procyclic acidic repetitive proteins of Trypanosoma brucei.

The procyclic acidic repetitive proteins (PARPs) of Trypanosoma brucei are developmentally regulated surface proteins encoded by a family of polymorphic genes. We have determined the complete nucleotide sequence of a novel member of the PARP gene family and investigated its expression. The amino acid sequence deduced from the parpA alpha gene showed a marked conservation of both the amino- and carboxy-terminal regions compared with other PARPs but revealed the substitution of a pentapeptide for the dipeptide repeating unit that is characteristic of all other PARPs. Northern hybridization analysis indicated that expression of the parpA alpha gene, like that of other members of this gene family, is confined to the procyclic stage of the T. brucei life cycle. This result implies coordinate regulation of the unlinked genetic loci that encode PARPs.