Assignment of proximal histidyl imidazole exchangeable proton NMR resonances to individual subunits in hemoglobins A,Boston, Iwate and Milwaukee

The proton nmr spectra of the synthetic valency hybrids, α₂(β⁺CN)₂, (α⁺CN)₂β₂ of hemoglobin A and the natural valency hybrids of the mutant hemoglobins Boston, Iwate and Milwaukee have led to the unambiguous assignment of the two proximal histidyl imidazole exchangeable proton signals at 64 and 76 ppm to individual α and β subunits, respectively. New single non-exchangeable proton resonances detected in the extreme downfield region of the spectra of Hbs Boston and Iwate are tentatively assigned to the coordinated tyrosine of the mutated α chains.     

Apolipoprotein A-IV polymorphism in man

Summary In man, apolipoprotein A-IV is characterized by a genetically determined polymorphism controlled by two codominant alleles. Two isoforms of this apolipoprotein, designated A-IV-1 and A-IV-2, can be identified by isoelectric focusing. Among 1000 healthy factory workers participating in an epidemiological study, A-IV-1 (genotype 1-1) was observed in 85%; A-IV-2 (genotype 2-2), in 0.5%; and A-IV-1 in combination with A-IV-2 (genotype 1–2), in 14%. In four nonrelated subjects, an apolipoprotein A-IV variant (A-IV-Münster), characterized by a slightly more basic isoelectric focusing behavior than A-IV-2, was detected in combination either with A-IV-1 or A-IV-2. Mendelian inheritance of this variant could be demonstrated.     

Genetic control of human apolipoprotein E polymorphism: Comparison of one-and two-dimensional techniques of isoprotein analysis

Summary Genetic polymorphism of human apolipoprotein E (apo E) has previously been demonstrated by one-dimensional isoelectric focusing (Utermann et al. 1977b) and by two-dimensional electrophoresis of apolipoproteins (Zannis et al. 1981), but the relationship between the results obtained by these methods remained unclear. We therefore performed comparative phenotyping by one-dimensional and two-dimensional electrophoresis. Apoproteins from very low-density lipoproteins (apo VLDL) prepared by ultracentrifugation or from an apo Erich lipoprotein fraction prepared by heparin/Mg⁺⁺ precipitation, were used as a source of apo E. Six common phenotypes designated apo E-4/4, apo E-N/N, apo E-D/D, apo E-4/N, apo E-4/D, and apo E-N/D were differentiated irrespective of the technique used or the source of apolipoproteins, but the two-dimensional electrophoresis of apo VLDL and apo VLDL which had been treated with neuraminidase was the key for the correct genetic interpretation of those phenotypes exhibiting the E4 isoform of the protein. Each phenotype is characterized by the presence of either one or two of three major isoforms E2, E3, and E4 and by the presence of several minor sialylated forms of these proteins (apo E_s) that have higher apparent molecular weights. The unsialylated major isoform apo E2 does not only differ in charge but also has a higher apparent mol.wt. (about 34,500) than the major isoforms apo E3 and apo E4 (mol. wt. about 33,000). Family studies including 90 matings with a total of 203 offspring confirmed the genetic one locus model of Zannis et al. (1981). Apo E phenotypes are controlled by three autosomal codominant alleles apo E^d, apo Eⁿ, and apo E⁴ that specify for the E2, E3, and E4 isoforms respectively. Phenotypes apo E-D/D,-N/N, and-4/4 represent homozygotes and phenotypes apo E-4/N,-4/D, and-N/D heterozygotes for these alleles.The frequencies of apo E alleles in 1031 blood donors were apo E⁴=0.150, apo Eⁿ=0.773, and apo E^d=0.077. Homozygosity for the allele apo E^d is associated with hyperlipoproteinemia type III. Hence a large number of the population (about 1%) are at risk for this specific lipoprotein disorder that is associated with premature atherosclerosis and xanthomatosis.     

Biological activity of the antitumor protein neocarzinostatin coupled to a monoclonal antibody by N-succinimidyl 3-(2-pyridyldithio)-propionate

The chromophore free apoprotein of neocarzinostatin was coupled to monoclonal IgG₁ antibody using N-Succinimidyl 3-(2-pyridyldithio)-propionate as heterobifunctional reagent. After coupling active chromophore was reassociated with the apoprotein. We present here experimental evidence that the hybrid protein retains biological activity as measured by the degradation of T2-DNA and bacteriostatic action.     

Regulatory interrelations between GABA and polyamines. I. Brain GABA levels and polyamine metabolism

Elevation of brain GABA levels by GABA-T inhibition is accompanied by a decrease ofS-adenosylmethionine decarboxylase activity. This is followed by an increase of ornithine decarboxylase activity and a severalfold increase of brain putrescine levels. Spermidine and spermine levels are not significantly affected under these conditions. These unexpected findings support a regulatory interaction between GABA and polyamine metabolism.     

cell clones and pattern formation: Studies onsevenless,a mutant ofDrosophila melanogaster

Summary sev ^LY3,the only existing allele at thesev locus (1–33,2±0,2), behaves as strongly hypomorph or even as amorph. Ommatidia in asev compound eye have only seven receptor cells, the position of the R7 pattern element being vacant. Various criteria showing that the missing cell is R7 have been verified. These include (i) anatomical characteristics ofsev ommatidia; (ii) behaviour of central R cells insev rdgB double mutants; (iii) medullary projection of central R cell axons; and (iv) mitotic pattern ofsev imaginal discs. The analysis of morphogeneticsev-sev ⁺ mosaics has shown thatsev is expressed autonomously by R7 cells, indicating that thesev phenotype is not due to asev genotype of ommatidial pattern elements other than R7. The study of third instarsev imaginal discs has not brought any direct evidence for death of clustered presumptive R7 cells; however, clonal analysis of the developingsev compound eye has given evidence of developmental parameters comparable to those ofsev ⁺, therefore favouring the hypothesis that R7 cells die insev mutants. On the other hand,sev ⁺ seems to be required for the determination of the R7 cells, since thesev phenotype cannot be uncovered during the last mitoses of heterozygous mutant cells.     

Below-ground carbon distribution in barley (Hordeum vulgare L.) with and without nitrogen fertilization

The distribution of net assimilated C in barley (Hordeum vulgare L.) grown at two N-levels was determined in a growth chamber. The N-fertilization involved 0 and 3.61 mol N g^-1 dry soil. After growth for seven weeks in an atmosphere with continuously ¹⁴C-labelled CO₂, ¹⁴C was determined in shoots, roots, rhizosphere respiration and soil. At the low N-level, 32% of the net assimilated ¹⁴C was translocated below ground, whereas at the high N-level 27% was translocated below ground. The release of C from roots (root respiration, microbial respiration originating from decomposition of ¹⁴C-labelled root material and ¹⁴C remaining in soil) was greater with no N-supply (19% of net assimilated ¹⁴C) than in the treatment with N-supply (15%). Thus, the effect of N-supply on both translocation of assimilated ¹⁴C below ground and the release of ¹⁴C from growing roots was relatively small.     

Trichosporon mycotoxinivorans sp. nov., a new yeast species useful in biological detoxification of various mycotoxins

A yeast strain isolated from the hindgut of the lower termite Mastotermes darwiniensis (Mastotermitidae) was found to represent a new member of the genus Trichosporon. Trichosporon mycotoxinivorans is closely related to T. loubieri on the basis of the phylogenetic trees based on the D1/D2 region of 26S rDNA, an approx. 600 bp fragment of the 18S rDNA and both ITS regions. However, the two species differ at nine positions in the D1/D2 region of 26S rDNA. The IGS1 region of T. mycotoxinivorans is 401 bp long. T. mycotoxinivorans is distinguished from T. loubieri by its ability to assimilate inulin and galactitol, and its inability to grow at 40 °C. The name of this newly isolated strain refers to an important characteristics of T. mycotoxinivorans to detoxify mycotoxins such as ochratoxin A and zearalenone. Therefore this strain can be used for the deactivation of the respective mycotoxins in animal feeds.