Elimination of multiple innervation in the developing avian superior oblique muscle (1)

Motor endplates in the developing avian superior oblique muscle first appear on day 18 of incubation. Most of the endplates from this time through hatching (day 27) are innervated by multiple fibers. Each endplate in the post-hatching period is innervated by only one fiber. Time of elimination of multineuronal innervation does not correlate with the time of trochlear neuron loss; the former occurs much later in development. Removal of multiple innervation is therefore, not the cause of the naturally occurring neuron loss.     

Isolation and characterization of Arthrobacter bacteriophages and their application to phage typing of soil arthrobacters.

Seventeen bacteriophages, active against 19 Arthrobacter soil isolates, were isolated from concentrated samples of river water and sewage. Attempts to isolate Arthrobacter bacteriophages from filtrates of broth cultures of the soil isolates or from ultraviolet light-irradiated cultures were unsuccessful. Bacteriophages were not detected in either concentrated or unconcentrated soil extracts. Electron microscopic studies of 11 phages showed morphologies characteristic of Bradley's groups B (exhibited by 9 phages) and C (exhibited by 2 phages). Moles percent guanine plus cytosine, calculated from the deoxyribonucleic acid density of three phages, ranged from 60.2 to 65.3. The phages were characterized by their plague and virion morphology, host range, and serological specificity.     

Histone H2B variants from the erythrocytes of an amphibian, a reptile and a bird

Histones H2B have been isolated from the terminally differentiated diploid erythrocytes of three different classes, amphibia (Xenopus laevis), reptilia (Crocodilus niloticus) and aves (Gallus domesticus). Partial amino acid sequences revealed three regions of sequence variation, each variant involving a single amino acid substitution.     

Structure and composition of intracytoplasmic membranes of Ectothiorhodospira mobilis

The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein.Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching.Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10–15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.     

Defining essential stem cell characteristics in adipose-derived stromal cells extracted from distinct anatomical sites

The discovery of adipose-derived stromal cells (ASCs) has created many opportunities for the development of patient-specific cell-based replacement therapies. We have isolated multiple cell strains of ASCs from various anatomical sites (abdomen, arms/legs, breast, buttocks), indicating widespread distribution of ASCs throughout the body. Unfortunately, there exists a general lack of agreement in the literature as to their "stem cell" characteristics. We find that telomerase activity and expression of its catalytic subunit in ASCs are both below the levels of detection, independent of age and culturing conditions. ASCs also undergo telomere attrition and eventually senesce, while maintaining a stable karyotype without the development of spontaneous tumor-associated abnormalities. Using a set of cell surface markers that have been promoted to identify ASCs, we find that they failed to distinguish ASCs from normal fibroblasts, as both are positive for CD29, CD73 and CD105 and negative for CD14, CD31 and CD45. All of the ASC isolates are multipotent, capable of differentiating into osteocytes, chondrocytes and adipocytes, while fibroblasts show no differentiation potential. Our ASC strains also show elevated expression of genes associated with pluripotent cells, Oct-4, SOX2 and NANOG, when compared to fibroblasts and bone marrow-derived mesenchymal stem cells (BM-MSCs), although the levels were lower than induced pluripotent stem cells (iPS). Together, our data suggest that, while the cell surface profile of ASCs does not distinguish them from normal fibroblasts, their differentiation capacity and the expression of genes closely linked to pluripotency clearly define ASCs as multipotent stem cells, regardless of tissue isolation location.     

High affinity GDP binding sites on brown adipose tissue mitochondria of genetically obese ‘fa/fa’ rats

The number of high affinity [³H]GDP binding sites in brown adipose tissue mitochondria is normal in obese ( f a / f a ) rats in contrast to the reduced number of low affinity GDP binding sites. Adrenalectomy corrected the loss of low affinity binding sites in fa/fa rats but had no effect on the number of high affinity sites in either lean or obese rats. Equilibrium dialysis was used to show the presence of both high and low affinity binding sites on the purified 32 kdalton protein.