Structure of the yeast ribosomes. Proteins associated with the rRNA.

Polyamines have been shown to bind to doubled stranded regions of rRNA [3]. Therefore, ribosomal proteins that can be cross linked to these molecules in the ribosomes structure must be bound to or located in the vicinity of the RNA. This technique is the first to yield results on the proteins associated with the rRNA in the eukaryotic ribosome where the lack of purified ribosomal proteins does not allow the use of direct binding studies as in bacterial systems. Proteins S7, S10, S13, S21, S22 and S27 in the small subunit and L2/3, L5, L10/12, L19/20, L22, L23, L36/37, L42 and L43' in the large subunit are labelled when cross linked to [14C]spermidine using 1,5-difluoro 2,4-dinitrobenzene and are good candidates to be RNA-binding proteins in ribosomes from Saccharomyces cerevisiae.     

Chronorhythms of the circulating erythrocytes and leukocytes--correlation with the E.S.R. cycles

2750 healthy and fasting subjects, 20-30 years old, were studied over a half-year period in 1980. Considering the mean day value as a basic piece of information for statistics, the Erythrocyte Sedimentation Rate (E.S.R.) and the blood counts (erythrocytes, leukocytes, polymorphonuclears, lymphocytes, monocytes and eosinophils) were compared. The timeless relation between E.S.R. and each cell type number or percentage is rectilinear. The stronger slope and relation apply to the polymorphonuclears (PMN) or to the overall leukocytes. The chronological normalized variations of the E.S.R. and of the PMN or leukocyte number or percentage are highly correlated. E.S.R. is less correlated with monocytes, eosinophils and Lymphocytes. Contrary to what could have been expected, the erythrocyte situation is but an intermediate one. The spectra derived from the time variations show that all the cell types, whatever they are, are to be taken into account to explain the E.S.R. value and variation with time, even if, for a given cell type, the correlation and timeless relation were but faint ones. Each cell type has a specific spectrum. Erythrocytes are subject to low frequency variations (316-158 days). PMNs oscillate with time within the medium frequency range (90 days). Lymphocytes, monocytes and eosinophils fluctuate more quickly (53 days).     

Synergistic interaction of the streptogramins with the ribosome.

Quantitative binding studies of [G-3H]streptogramin A and [G-3H]streptogramin B with high-salt-washed ribosomes were carried out in the presence of a minimum of 10% (v/v) ethanol because of the antibiotic insolubility in water. It was observed that the presence of streptogramin A increases the affinity of [G-3H]streptogramin B for the ribosome. Thus the dissociation constant for [G-3H]-streptogramin B interaction with the ribosome is Kd=13.3 nM in the presence of streptogramin A and Kd=59 nM in its absence. Furthermore the values for the dissociation constants for [G-3H]-streptogramin B interaction in the presence of 50% (v/v) ethanol, were Kd=0.13 micronM in the presence of streptogramin A and Kd=0.70 micronM in its absence. This increased affinity of [G-3H]streptogramin B in the presence of streptogramin A can explain the synergistic effects of mixtures of streptogramins A and B at the ribosome level.     

Experience with the deltopectoral flap.

The deltopectoral flap is a most versatile source of skin coverage or mucosal lining (or both). There is remarkable safety in the use of this flap in relation to its size, and there is only limited need for delay--because it pedicle is an axial flap. Nonetheless, the terminal part requires the attention to detail which any random flap requires--such as the avoidance of hematoma and infection and the prevention of tension, kinking, and angulation. This not only will ensure the safety of the flap, but also will prevent the rather common and annoying minor complications that delay the patient's convalescence.     

Tyrosine phosphorylation of calponins. Inhibition of the interaction with F-actin.

The phosphorylation-dephosphorylation of serine and threonine residues of calponin is known to modulate in vitro its interaction with F-actin and is thought to regulate several biological processes in cells, involving either of the calponin isoforms. Here, we identify, for the first time, tyrosine-phosphorylated calponin h3 within COS 7 cells, before and after their transfection with the pSV vector containing cDNA encoding the cytoplasmic, Src-related, tyrosine kinase, Fyn. We then describe the specific tyrosine phosphorylation in vitro of calponin h1 and calponin h3 by this kinase. 32P-labeling of tyrosine residues was monitored by combined autoradiography, immunoblotting with a specific phosphotyrosine monoclonal antibody and dephosphorylation with the phosphotyrosine-specific protein phosphatase, YOP. PhosphorImager analyses showed the incorporation of maximally 1.4 and 2.0 mol of 32P per mol of calponin h3 and calponin h1, respectively. As a result, 75% and 68%, respectively, of binding to F-actin was lost by the phosphorylated calponins. Furthermore, F-actin, added at a two- or 10-fold molar excess, did not protect, but rather increased, the extent of 32P-labeling in both calponins. Structural analysis of the tryptic phosphopeptides from each 32P-labeled calponin revealed a single, major 32P-peptide in calponin h3, with Tyr261 as the phosphorylation site. Tyr261 was also phosphorylated in calponin h1, together with Tyr182. Collectively, the data point to the potential involvement, at least in living nonmuscle cells, of tyrosine protein kinases and the conserved Tyr261, located in the third repeat motif of the calponin molecule, in a new level of regulation of the actin-calponin interaction.