Development of heart cells in culture: studies using an affinity purified antibody to a myosin light chain

Cultured neonatal rat heart cells can be used to study the factors that regulate cardiac contractility and myocyte development in vitro. An antibody to the 26,000 dalton light chain of myosin (MLC1), has been produced and purified on a Sepharose 4B affinity column prepared with rat heart myosin. When primary cultures of myocytes are studied by indirect immunofluorescence using this antibody a predictable pattern of myofibrillar structure is observed to develop over 72 h. This myosin cytoskeleton is highly organized and the myosin fibrils exhibit cross striations. The antibody does not stain non-muscle heart cells and there is no evidence for myocyte division in culture. The qualitative immunofluorescent pattern of myosin organization is the same in both spontaneously beating and in non-contracting cells.     

Defective in vitro T cell colony formation in the acquired immunodeficiency syndrome

Depressed T cell immunity is a universal characteristic of the acquired immunodeficiency syndrome (AIDS). In the present study, 25 patients with AIDS and opportunistic infections, 22 individuals with AIDS-related complex (ARC, or chronic lymphadenopathy syndrome), and 20 healthy homosexuals were evaluated by means of the T cell colony assay. Forty-seven healthy heterosexual controls showed an average of 3964 +/- 319 colonies/7.5 X 10(5) cells, with a range of 880 to 9340. The mean in the 20 healthy homosexuals (3173 +/- 483) did not differ significantly from the controls; in this group, only three patients had values less than 1000 colonies/plate. By contrast, all AIDS patients and 14 ARC patients had colony counts less than 1000. The mean value for the AIDS patients was only 24 +/- 15 (p less than 0.0005 compared with either controls or healthy homosexuals); values in the ARC group were intermediate (1180 +/- 360). The addition of interleukin 2 to the plates promoted correction of the proliferative abnormality in ARC patients. This interleukin increased colony scores in the AIDS group, but the mean value was still significantly less than controls. Comparison indicated that the colony assay is a more sensitive indicator for detecting proliferative abnormalities than responses to PHA, Con A, or pokeweed mitogen in suspension cultures.     

DNA sequence patterns in human,mouse, and rabbit immunoglobulin kappa-genes

Summary DNA sequences of the human, mouse, and rabbit immunoglobulin kappa-gene (J-C regions) are compared with respect to various DNA patterns, including dyad symmetry pairings, runs of nucleotides, repeat clusters, and repeats that occur with unusually high frequency. The significant dyad symmetry pairings within each of the sequences emphasize the two control-enhancer elements of the J₅-C intron. Dyad symmetry pairs between the J-C region and a number of kappa variable (V)-gene domains suggest differences in the affinities between the V and J segments. It is the consensus heptamer rather than the consensus nonamer that embodies the longest V-J dyad symmetry combinations. In the rabbit there are long runs and repeat clusters of the sequences that identify regions of high duplication; these regions are absent in the human and mouse sequences. High-frequency oligonucleotides feature the consensus nonamer 5 to the J segments, especially in the mouse sequence.     

Temporal fluctuations of silver,copper and zinc in the bivalve Macoma balthica at five stations in South San Francisco Bay

Concentrations of Cu, Ag and Zn were measured in the soft tissues of the estuarine bivalve Macoma balthica in South San Francisco Bay at near-monthly intervals for periods of two to three years at four stations, and eight years at a metal-enriched station. The amplitude and frequency of fluctuations differed among stations and among metals. Fluctuations were greatest at stations with the greatest metal enrichment and with the least dilution and flushing of wastes. A consistent seasonal pattern of fluctuation in Cu and Ag concentrations was evident in M. balthica at the metal-enriched station. These seasonal changes in tissue metal concentrations appeared to be affected by metal inputs, hydrologic processes that may affect both metal concentrations and bioavailability, and seasonal changes in the weight of the bivalve. The contributions of each of these interacting factors could not be determined quantitatively. At the metal-enriched station significant variation in the amplitude of seasonal fluctuations was also evident from year to year. Interpretation of metal concentrations in bivalves from estuaries will require careful consideration of the processes which affect metal dynamics in these complex environments.     

Transformation by SV 40 virus sensitizes fibroblasts of human skin to the lytic action of H-1 parvovirus

Human skin fibroblasts which are naturally resistant to Parvovirus H-1 can be lysed by this virus after SV40 transformation. This observation raises the possibility that oncosuppression by Parvovirus involves a direct oncolytic effect.     

Digestion of prey in foraminifera is not anomalous: A correlation of light microscopic, cytochemical, and hvem technics to study phagotrophy in two allogromiids

Correlative light, high-voltage electron and conventional electron microscopic methods were used to investigate digestion in two allogromiid foraminiferans, Allogromia sp., strain NF, and A. laticollaris Arnold. Microscopic observations showed that bacterial prey are phagocytosed by reticulopodia and are transported to the allogromiid cell body within blister-like phagosomes. Larger prey (algae, diatoms) are transported along the reticulopodial surface and are either stored extrathalamously or phagocytosed at the oral opening (peduncle). Studies of allogromiids optimally fixed and labeled with an extracellular-space label (colloidal thorium) showed that phagocytosed prey are completely enclosed by a plasma membrane envelope; this finding was corroborated by a serial-section three-dimensional reconstruction of the oral zone of one allogromiid. Cytochemical staining for acid phosphatase showed that lysosomes are absent from reticulopods but abundant in the cell body, particularly in the oral zone cytoplasm. We conclude that digestion in allogromiid foraminiferans is accomplished by a vacuole-based digestive apparatus and not by extracellular digestion within a lacunary system, as has been suggested in earlier studies.     

Serum melatonin and pineal indoleamine metabolism in a species with a small day/night N-acetyltransferase rhythm

Ovine serum and pineal melatonin levels are low during the day, increase five to ten-fold at night, decrease during a light pulse at night, and rapidly increase to night levels following the light-dark transition. N-Acetyltransferase activity increases three-fold at night, falls significantly in response to the light pulse, but does not increase following the light pulse. No significant change in N-acetylserotonin occurs under these conditions. These results suggest that the biochemical mechanisms controlling pineal melatonin synthesis in the sheep pineal gland may be different from those in the rat.     

Extracellular lumazine from aggregating Dictyostelium discoideum cells. Influence of pH on its fluorescence

Lumazine has been demonstrated to be one of the two main compounds responsible for the extracellular fluorescence linked with the aggregation ability of Dictyostelium discoideum, strain Ax-2. The other compound, also having lumazine properties, is, however, different from the 7-hydroxylumazine proposed previously. The influence of pH on the fluorescence of lumazine was studied. The possible use of extracellular pteridines as pH markers was stressed and a method for the determination of the amount of "lumazine equivalents" in the extracellular medium of aggregating D. discoideum cells is elaborated.