Characterization of human blood platelet membrane proteins and glycoproteins by their isoelectric point (pI) and apparent molecular weight using two-dimensional electrophoresis and surface-labelling techniques

Intact human blood platelets were radioactively labelled at the surface by techniques specific for proteins or glycoproteins. Labelled platelet samples were analyzed by a high-resolution two-dimensional separation system involving isoelectric focusing in the first dimension and discontinuous sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the second. The major platelet membrane glycoprotein (GP) bands (Ib, IIb, IIIa and IIIb) were found to be highly heterogeneous even after removal of terminal sialic acid residues. Lactoperoxidase-catalyzed iodination of platelets showed that the major labelled proteins (Ib, IIb, IIIa and IIIb) had altered isoelectric points ($\text{p}\text{I}$) and molecular weights after neuraminidase treatment. A number of membrane glycoproteins previously undetected by one-dimensional gel electrophoresis were demonstrated and good evidence provided that the major platelet surface proteins are glycosylated.     

Detection of the Viral Sarcoma Gene Product in Cells Infected with Various Strains of Avian Sarcoma Virus and of a Related Protein in Uninfected Chicken Cells

Genetic analyses have defined a single gene (src) as that portion of the avian sarcoma virus (ASV) genome which encodes the protein directly responsible for ASV-induced neoplastic transformation. We have recently identified the polypeptide product of the src gene of the Schmidt-Ruppin (SR) strain of ASV, a 60,000-dalton phosphoprotein designated pp60(src), and have further determined that pp60(src) acts as a protein kinase. Essential to the identification and characterization of the pp60(src) protein of SR-ASV was the use of serum (TBR serum) from rabbits bearing SR-ASV-induced tumors. TBR serum was, however, strain specific, recognizing pp60(src) from SR-ASV-transformed cells only. We report here that sera from marmosets bearing tumors induced by the Bryan or SR strains of ASV (TBM sera) contain antibody which precipitates the transforming gene product from cells transformed by the SR, Bryan, Prague, or Bratislava strains of ASV. In contrast, rabbits bearing tumors induced by either the Bratislava or Bryan strains of ASV, or hamsters with SR-ASV-induced tumors did not produce antibody to pp60(src) from any strain of ASV. The 60,000-dalton polypeptides immunoprecipitated with TBM serum from cells transformed by each of the above virus strains are phosphoproteins. One-dimensional peptide mapping by limited proteolysis revealed that the pp60(src) proteins are structurally very similar, but not identical. Furthermore, all of the viral pp60(src) proteins have an associated phosphotransferase activity. In addition to detecting the viral src proteins, TBM serum was able to immunoprecipitate an antigenically related protein from normal uninfected avian cells.     

A functional evenness index for microbial ecology

Microbial ecologists attempting to describe community structures through the use of synthetic parameters face enormous difficulties. These stem in part from the necessity of using standard taxonomic reference levels in a field where the species level is poorly defined. This paper presents an attempt to obviate this problem. A “functional evenness” index (E) is defined using information measures; it is based directly on the characteristics of the bacteria, as determined, for example, with the API 20B method. Comparisons of this index with classic structure indices, such as taxonomic evenness (Pielou) or systematic dominance (Hulburt), show that it behaves like an evenness index, while bypassing the taxonomic study required before computation of the classic indices. Its use is illustrated with samples of aerobic heterotrophic bacteria obtained from brackish lagoon sediments. We are grateful to our statistician colleagues, Dr. Yves Lepage from Université de Montréal and Dr. André Plante from Université du Québec à Montréal. Both have contributed important elements to the discussion presented in this Appendix.     

Glucose turnover during pregnancy in anaesthetized post-absorptive rats

During pregnancy the decline in blood [glucose] does not result from the increased distribution space of glucose. The absolute rate of glucose turnover increases in late pregnancy in parallel with the rise in the mass of the conceptus. Nevertheless, glucose turnover per kg body wt. is not increased in late pregnancy, since the lower blood [glucose] decreases glucose utilization by maternal tissues.     

Solution conformation of Monensin free acid,a typical representative of the polyetherin antibiotics

The solution conformation of the ionophore Monensin in its free-acid form bears a close resemblance to that of its Na⁺ salt. The backbone is folded into a closed loop, and the pseudocyclic structure is shut by head-to-tail H bonding between the carboxylic function and the alcoholic functions of the last six-membered ring with the mediation of a water molecule. A mode of trapping is proposed and compared to features observed in some other membrane-active complexones.     

Genetic control of igG2a production in the response to sheep erythrocytes

A low IgG2a response in B10 mice during the primary response to sheep red blood cells (SRBC) is described. Analysis of the response in B10 × BALB/c hybrid progenies and in congenic strains indicates that this low response is a dominant phenotype placed under the control of a single Mendelian gene or a group of closely linked genes. This gene(s) is neither linked to CH allotypes orH2 haplotypes, nor is it sex-linked. It can be considered as an isotype- and antigenspecific regulatory gene of the immune response.     

Antenna chlorophyll in photosynthetic membranes. A study by resonance Raman spectroscopy

Raman spectra of antenna chlorophyll a and chlorophyll b were selectively obtained from chloroplasts of green plants and from monocellular algae, using resonance enhancement in the respective Soret bands of these molecules, at 35 K. It is shown that:

Antenna chlorophyll a molecules occur in at least five discrete categories, distinguished by different extramolecular bonding of their 9-keto carbonyl groups.

These vibrational categories are probably identical in nature and number among the different organisms studied, but differ in their relative populations.

Chlorophyll b molecules occur in at least two different categories differing by the strength of the interactions of their 3-formyl C = 0 groups. These vibrational categories also appear as universal.

Most chlorophyll a and b molecules have their magnesium atoms bound to a single foreign ligand, whose nature may depend on the population considered.

Resonance Raman spectra of antenna structures, including those of organisms devoid of chlorophyll b, were compared to resonance Raman spectra of chlorophyll a and b in monomeric, oligomeric and hydrated polymeric states, at room temperature and at 35 K. No sizable amount of antenna chlorophyll a or b occurs as dry or hydrated oligomers, or polymers. The antenna molecules are thus necessarily bound to foreign molecules, probably proteins, through H-bonding on their formyl and/or keto carbonyl groups and through bonding of their magnesium atoms.