Carnivora: the primary structure of the common otter (Lutra lutra, Mustelidae) hemoglobin

The hemoglobin of the Common Otter (Lutra lutra, Carnivora) contains only one component. The complete primary structures of the alpha- and beta-chains are presented. They were separated by high-performance liquid chromatography and the sequences determined by automatic liquid and gas-phase Edman degradation of the chains and their tryptic peptides. The alpha-chains show 18 and the beta-chains 13 substitutions compared to human alpha- and beta-chains, respectively. In the alpha-chains one heme- and two alpha 1/beta 1-contacts are exchanged. In the beta-chains the replacements involve one heme-, one alpha 1/beta 1-, and one alpha 1/beta 2-contact. The alpha- and beta-chains of the Common Otter are compared to those of other Carnivora hemoglobins. The unexpected low number of substitutions between Common Otter hemoglobin and that of Lesser Panda as well as of Harbor Seal is discussed.     

Microtubule and microfilament distribution and tubulin content in the cell cycle of Indian muntjac cells

Using DAPI, rabbit antitubulin antibody, FITC-labeled goat anti-rabbit IgG, and TRITC-phalloidin to stain individual cells, the microspectrophotometric analysis showed that three markers that represent the nucleus, microtubules (MT), and microfilaments (MF), respectively, could be recognized in individual cells without interference. The phase of the cell cycle was determined by DNA content. We found that in Indian muntjac (IM) cells, the amount of tubulin in G2 and M phases was about twice as much as that in G1 phase. In G2 cells, the cytoplasmic microtubule complex (CMTC) became denser than in G1 cells. The cytoplasmic MT extent in basically the same orientation as MF bundles in interphase. The regions where the MT is denser also have a denser MF distribution.     

Evidence for a non-opioid sigma binding site in the guinea-pig myenteric plexus

The presence of a binding site to (+)-(3H)SKF 10,047 was demonstrated in a guinea-pig myenteric plexus (MYP) membrane preparation. Specific binding to this receptor was saturable, reversible, linear with protein concentration and consisted of two components, a high affinity site (KD = 46 +/- 5 nM; Bmax = 3.4 +/- 0.5 pmole/g wet weight) and a low affinity site (KD= = 342 +/- 72 nM; Bmax = 22 +/- 3 pmole/g wet weight). Morphine and naloxone 10(-4) M were unable to displace (+)-(3H)SKF 10,047 binding. Haloperidol, imipramine, ethylketocyclazocine and propranolol were among the most potent compounds to inhibit this specific binding. These results suggest the presence of a non-opioid haloperidol sensitive sigma receptor in the MYP of the guinea-pig.     

Five genetic loci involved in the synthesis of acidic exopolysaccharides are closely linked in the genome of Rhizobium sp strain NGR234

Summary R-prime plasmids were constructed from a derivative of Rhizobium strain NGR234 (ANU280) and were shown to contain overlapping genomic DNA segments involved in biosynthesis of exopolysaccharides (EPS). The R-primes originally constructed carried the mutant allele from Tn5-induced EPS-deficient (Exo^–) mutant ANU2811. This plasmid-located mutant allele was dominant to the corresponding wild-type allele as merodiploid strains were Exo^–. Exo⁺ revertants occurred at a low rate (1×10^-7) and these were shown to result from double reciprocal recombination events, which led to the isolation of R-prime plasmids carrying functional wild-type exo alleles. R-prime plasmids that carry overlapping segments of DNA from parental strain ANU280 complemented 28 of the 30 group 2 Exo^– mutants of strain ANU280. Complementation of these Exo^– mutants also restored their symbiotic abilities of effective nodulation. Subsequent in vivo recombination between the wild-type alleles located on the R-prime and the corresponding mutated allele on the genome, was used to generate a new family of R-primes, which carried mutations in the exo genes. The 30 group 2 Exo^– mutants were classified into 7 distinct genetic groups based upon complementation and physical mapping data. Five of the seven exo loci were gentically linked and located on a 15-kb region of DNA. Mutations at two loci were dominant only when the mutations were R-prime plasmid-located while a mutation at a second locus was cis-dominant to two other exo loci. At least five genes involved in the synthesis of acidic exopolysaccharide synthesis have been identified.     

A developmentally regulated hydroxyproline-rich glycoprotein in maize pericarp cell walls

We have studied the accumulation of peptidyl hydroxyproline in the pericarp of developing maize (Zea mays L., Golden cross Bantam sweet corn) kernels. Although this hydroxyproline accumulates throughout development, it is most soluble and its content per milligram dry weight greatest at midmaturation stages of development. Salt-soluble proteins containing this hydroxyproline from isolated cell walls of developing kernels were fractionated on a CsCl density gradient and on a Chromatofocusing column, resulting in the purification of an hydroxyproline-rich glycoprotein, PC-1. PC-1 is a basic protein of approximately 65 to 70 kilodaltons in molecular weight with an isoelectric point of at least 10.2 and a density of 1.38 to 1.39 in CsCl. Amino acid composition data indicate that it is rich in hydroxyproline, threonine, proline, lysine, and glycine. Its relation to dicot extensin is discussed.     

Expression of an ouabain-resistant Na,K-ATPase in CV-1 cells after transfection with a cDNA encoding the rat Na,K-ATPase alpha 1 subunit

We have used a gene transfer system to investigate the relationship between expression of the rat Na,K-ATPase alpha 1 subunit gene and ouabain-resistant Na,K-ATPase activity. A cDNA clone encoding the entire rat Na,K-ATPase alpha 1 subunit was inserted into the expression vector pSV2neo. This construct (pSV2 alpha 1) conferred resistance to 100 microM ouabain to ouabain-sensitive CV-1 cells. Hybridization analysis of transfected clones revealed the presence of both rat-specific and endogenous Na,K-ATPase alpha 1 subunit DNA and mRNA sequences. A single form of highly ouabain-sensitive 86Rb+ uptake was detected in CV-1 cells, whereas two distinct classes of ouabain-inhibitable uptake were observed in transfectants. One class exhibited the high ouabain sensitivity of the endogenous monkey Na,K-ATPase, while the second class showed the reduced ouabain sensitivity characteristic of the rodent renal Na,K-ATPase. Examination of the ouabain-sensitive, sodium-dependent ATPase activity of the transfectants also revealed a low affinity component of Na,K-ATPase activity characteristic of the rodent kidney enzyme. These results suggest that expression of the rat alpha 1 subunit gene is directly responsible for ouabain-resistant Na,K-ATPase activity in transfected CV-1 cells.     

Epitopes of an influenza viral peptide recognized by antibody at single amino acid resolution

Antibodies raised against the synthetic peptide corresponding to the carboxy-terminal 24 amino acids (305-328) of the heavy chain of the hemagglutinin molecule of influenza virus A/X-31 (H3) bind this peptide at three antigenic sites. These sites were identified by assaying binding of polyclonal BALB/c mouse antipeptide sera to the complete set of all possible di-, tri, tetra-, penta-, hexa-, hepta-, and octapeptides homologous with the 24-residue sequence. Individual epitopes were defined and essential residues identified by testing the binding of monoclonal antibodies to sets of peptide analogues in which every one of the homologous residues was replaced in turn by each of the 19 alternative genetically coded amino acids. The immunodominant epitope was shown to be a linear sequence of five amino acids, 314LKLAT318. Replacement of any one of these residues with any other amino acid resulted in loss of antibody binding, indicating that all five are essential to the interaction and that they are probably contact residues. Another antigenic site contains at least two overlapping epitopes: polyclonal sera recognize predominantly an epitope or epitopes encompassed by the linear sequence 320MRNVPEKQT328, whereas the epitope defined by a particular monoclonal antibody comprises the seven amino acids 322NVPEKQT328, of which N322, E325, and Q327 were implicated as contact residues.     

异细胞质八倍体小黑麦的获得及其细胞遗传

改变小黑麦细胞质有可能增加减数分裂的稳定性,提高小黑麦的结实率与籽粒饱满度。作者以不同细胞质的“中国春”小麦与黑麦杂交,F_1幼苗用秋水仙素加倍获得双二倍体、或以八倍体小黑麦为父本与F_1杂交,获得异细胞质八倍体小黑麦(Triticale 8x)8个品系。实验结果表明:细胞质不同的“中国春”小麦与黑麦杂交结实率差异显著,出苗率亦不同,F_1株型多为两亲的中间型,花药不开裂,个别组合出现雄蕊雌化现象,有的组合表现生长弱性,减数分裂中期Ⅰ常出现1至数个末端交叉的棒状二价体,其数量在不同组合间差异显著,表明异细胞质对染色体配对有影响。D类细胞质对改进八倍体小黑麦的结实率可能有一定的作用。