Developmental biochemistry of cottonseed embryogenesis and germination. XIX. Sequences and genomic organization of the α globulin (vicilin) genes of cottonseed

The globulin storage protein genes of cotton are found to exist as gene tandems that contain a gene from each of the 2 globulin subfamilies separated by a spacer region of about 2700 or 3400 base pairs. Three different tandems have been identified by restriction endonuclease mapping of genomic DNA. A cDNA that is different from the genes of the tandems in map sites and/or in nucleotide sequence indicates that a fourth tandem probably exists in the cotton genome. Since the species of cotton used here (Gossypium hirsutum) is an amphidiploid, it is likely that two of the tandems are contributed from each genome.Considerable divergence in nucleotide sequence (18%) and in derived amino acid sequence (28%) is found when the 2 genes of a sequenced tandem are compared. The sequence of the cDNA closely resembles one of the genes in the tandem showing only a 4% divergence in nucleotides and a 4.2% divergence in amino acids. Thus the 2 genes of each tandem represent a relatively ancient gene duplication that has given rise to the two globulin subfamilies of cotton. Only one subfamily has a glycosylation site and the glycosylation of its derived proteins gives rise to the 2 molecular weight sets of globulins seen on gel electrophoresis.Other basic features of these genes and their derived proteins are presented.     

The sequence of rat leukosialin (W3/13 antigen) reveals a molecule with O-linked glycosylation of one third of its extracellular amino acids.

Leukosialin is one of the major glycoproteins of thymocytes and T lymphocytes and is notable for a very high content of O-linked carbohydrate structures. The full protein sequence for rat leukosialin as translated from cDNA clones is now reported. The molecule contains 371 amino acids with 224 residues outside the cell, one transmembrane sequence and 124 cytoplasmic residues. Data from the peptide sequence and carbohydrate composition suggest that one in three of the extracellular amino acids may be O-glycosylated with no N-linked glycosylation sites. The cDNA sequence contained a CpG rich region in the 3' coding sequence and a large 3' non-coding region which included tandem repeats of the sequence GGAT.     

Insulin-dependent intermolecular subunit communication between isolated alpha beta heterodimeric insulin receptor complexes

The dissociation of the purified human placental alpha 2 beta 2 heterotetrameric insulin receptor complex into an alpha beta heterodimeric state was found to occur in a pH- and dithiothreitol (DTT)-dependent manner. Formation of the alpha beta heterodimeric complex, under conditions which preserved tracer insulin binding and protein kinase activities (pH 8.75 for 25 min followed by 2.0 mM DTT for 5 min) occurred with an approximate 50% efficiency. The resulting nondissociated alpha 2 beta 2 heterotetrameric complexes could then be separated effectively by Bio-Gel A-1.5m gel filtration chromatography at neutral pH. The isolated DTT-treated but nondissociated alpha 2 beta 2 heterotetrameric complex was resistant to any further dissociation by a second round of DTT and alkaline pH treatment, whereas the isolated alpha beta heterodimeric complex was stable to spontaneous reassociation for at least 72 h at pH 7.60. Kinetic analyses of the insulin receptor protein kinase activity demonstrated that the insulin stimulation of glutamic acid:tyrosine (4:1) synthetic polymer phosphorylation for both the alpha 2 beta 2 heterotetrameric and alpha beta heterodimeric complexes occurred via an increase in Vmax without any significant change in Km. Examination of beta subunit autophosphorylation of the alpha beta heterodimeric complex, in the presence but not in the absence of insulin, demonstrated the appearance of the covalent 32P-labeled alpha 2 beta 2 heterotetrameric complex. Further, the initial rate of insulin-stimulated beta subunit autophosphorylation in the isolated alpha beta heterodimeric complex occurred in a dilution-dependent (intermolecular) manner. These data demonstrate that the isolated alpha beta heterodimeric insulin receptor complex is fully capable of expressing insulin-dependent activation of the beta subunit protein kinase domain with the covalent reassociation of the alpha beta heterodimeric complex into an alpha 2 beta 2 heterotetrameric disulfide-linked state.     

γ-Hydroxybutyric Acid in Subcellular Fractions of Rat Brain

The presence of gamma-hydroxybutyric acid (GHB) in synaptosome-enriched fractions of rat brain was ascertained using a GLC technique. The stability of GHB in synaptosomes was evaluated by addition of various gamma-aminobutyric acid (GABA) transaminase (GABA-T) inhibitors, GHB, or ethosuximide to the homogenizing medium. Furthermore, changes in whole brain GHB levels were compared with those in the synaptosomal fraction in animals treated with GABA-T inhibitors, GABA, or ethosuximide. GHB was present in synaptosome-enriched fractions in concentrations ranging from 40 to 70 pmol/mg of protein. There was no evidence for redistribution, leakage, or metabolism of GHB during the preparation of synaptosomes. The elevations of whole brain GHB level associated with GABA-T or ethosuximide treatment were reflected by a parallel increase in synaptosomal GHB content. These data add to the growing evidence that GHB may have neurotransmitter or neuromodulator function.     

Increased rates of illness and death from asthma in Canada.

Recent rates of illness and death from asthma in Canada and rates of hospital admission/separation for asthma were examined by age group and region. The death rates were higher in 1982-84 than in 1970-72, especially among those aged 15 to 34 years. Increases were also noted in hospital admission/separation rates, especially among those less than 15 years of age. Hospital admission/separation rates were highest in the Maritime provinces and Saskatchewan, whereas death rates were highest in Alberta and Saskatchewan. Examination of death certificates for coding errors and recoding of certificates to a single (8th) revision of the International Classification of Diseases indicated that changes in disease coding and errors in coding did not account for the significant increase in rates of death from asthma for those aged 15 to 34 years. These increases in rates of illness and death from asthma are unexplained and warrant further investigation.     

Important risk factors for death in adults: a 10-year follow-up of the Nutrition Canada survey cohort.

Data on mortality among over 8000 Canadians aged 35 to 79 years who participated in the Nutrition Canada survey are presented. The effects of various risk factors on mortality were assessed with a multivariate Poisson regression analysis. Factors associated with a significantly increased risk of death over a 10-year follow-up period ending in 1981 included cigarette smoking, hypertension and diabetes mellitus. A shallow U-shaped mortality pattern was observed for body mass index and for serum cholesterol level. No statistically significant increases in risk were associated with alcohol consumption. The population attributable risks for smoking, hypertension and diabetes were 39%, 8% and 6% respectively for men and 21%, 12% and 7% respectively for women.     

Nodulin-26, a peribacteroid membrane nodulin is expressed independently of the development of the peribacteroid compartment.

The peribacteroid membrane (pbm) of root nodules is derived from the plant cell plasma membrane but contains in addition several nodule-specific host proteins (nodulins). Antibodies raised against purified pbm of soybean were used to immunoprecipitate polysomes to isolate an RNA fraction that served as a template for the synthesis of a cDNA probe for screening a nodule-specific cDNA library. Clone p1B1 was found to encode a 26.5 kDa polypeptide (nodulin-26) which is immunoprecipitable specifically with the anti-pbm serum. Nodulin-26 has features of a transmembrane protein and its structure differs from that of nodulin-24 which appears to be a surface protein of pbm. The expression of these two pbm nodulins was examined in nodules induced by Bradyrhizobium japonicum Tn5 mutants that arrest nodule development at different stages of pbm biosynthesis. Nodules that do not show release of bacteria from the infection thread express nodulin-24 at a very low level. In contrast, the expression of nodulin-26 occurs fully in nodules that form infection threads only and is not affected by the release of bacteria from the threads.     

TheRT1.G locus in the rat encodes a Qa/TL-like antigen

A new antigenic system in the rat homologous to theQa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations that were matched for theRT1. A, B, D, E loci in the major histocompatibility complex (MHC): (R11×BN)F₁ anti-BN.1L(LEW), (R18×BN)F₁ anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic and recombinant strains identified three alleles,RT1.G ^a ,G ^b ,G ^c , of whichG ^c is a null allele. The strain distribution of these alleles was determined, using 37 strains of rats representative of all of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains showed that theRT1.G locus was linked to the MHC and that the most probable gene order wasA-E-G. Testcross analysis showed that the map distance betweenA andG was 1.4 cM(4/285 recombinants). The RT1.G antigen has a heavy chain ofM _r 46 000 and is present on both T and B cells.