A genetic map of potato (Solanum tuberosum) integrating molecular markers,including transposons,and classical markers

A genetic map of potato (Solanum tuberosum L.) integrating molecular markers with morphological and isozyme markers was constructed using a backcross population of 67 diploid potato plants. A general method for map construction is described that differs from previous methods employed in potato and other outbreeding plants. First, separate maps for the female and male parents were constructed. The female map contained 132 markers, whereas the male map contained 138 markers. Second, on the basis of the markers in common the two integrated parental maps were combined into one with the computer programme JoinMap. This combined map consisted of 175 molecular markers, 10 morphological markers and 8 isozyme markers. Ninety-two of the molecular markers were derived from DNA sequences flanking either T-DNA inserts in potato or reintegrated maize transposable elements originating from these T-DNA constructs. Clusters of distorted segregation were found on chromosomes 1,2,8 and 11 for the male parent and chromosome 5 for both parents. The total length of the combined map is 1120 cM.     

Auxin-Modulated Protein Disulfide-Thiol-Interchange Activity from Soybean Plasma Membranes

The renaturation of scrambled (oxidized and inactive) RNase A is catalyzed by soybean (Glycine max cv Williams 82) plasma membranes. The catalysis is stimulated by the auxin herbicide 2,4-dichlorophenoxyacetic acid or by the natural auxin indole-3-acetic acid. The inactive auxin analog, 2,3-dichlorophenoxyacetic acid, is without effect. The activity occurs in the absence of external electron acceptors or donors and therefore appears to be a true disulfide-thiol-interchange activity between protein disulfides and thiols of RNase A and those of plasma membrane proteins. The activity is not affected by a mixture of reduced and oxidized glutathione. However, no auxin-stimulated activity was observed in the presence of either oxidized glutathione or reduced glutathione alone, a response characteristic of the previously described auxin-stimulated NADH oxidase activity of soybean plasma membranes. Taken together, the results suggest the operation in the plant plasma membrane of a protein disulfide-thiol-interchange activity that is stimulated by auxins. The auxin stimulations of the interchange activity are prevented by glutathione, reduced glutathione, and brefeldin A at concentrations that also prevent auxin stimulation of NADH oxidation by isolated plasma membranes and inhibit, as well, the auxin-stimulated elongation of excised segments of soybean hypocotyls.     

Perilymphatic Fistula—A Definitive and Curable Cause of Vertigo Following Head Trauma

Vertigo or disequilibrium occurring in patients after concussive and nonconcussive head trauma may be due to a pathologic perilymphatic fistula from the inner ear through the oval and round window areas of the middle ear. Of 33 patients who had successful grafting of the fistulous area at middle ear exploration, 32 had resolution of vertigo, and 12 of 23 who had an associated hearing loss had improved hearing. Perilymphatic fistulas associated with vertigo and hearing loss after head trauma can be diagnosed with great certainty and are surgically curable in the great majority of cases. Patients with post-concussive syndrome, whose symptoms include vertigo or disequilibrium, should have a thorough otologic evaluation for the possibility of a perilymphatic fistula.     

Inhibitor studies with adenohypophyseal granule membrane ATPase. Evidence for a membrane environment which modulates sensitivity to inhibitors

The limiting membranes of pituitary growth hormone and prolactin secretory granules contain a Mg2+-ATPase sensitive to anions. This enzyme is in many ways similar to mitochondrial ATPase. The enzyme was potently inhibited by oligomycin (Ki 6.5 X 10(-9) M), and was much more sensitive to the inhibitor than pituitary mitochondrial ATPase (Ki 2.7 X 10(-7) M). In contrast, the enzyme activity of intact secretory granules was only sparingly inhibited by oligomycin (maximal inhibition close to 30% at 5 X 10(-4) M). However, oligomycin (5 microM) did diminish to basal levels the enhanced granule ATPase activity observed in the presence of a stimulatory anion (25 mM sodium sulfite). Other compounds known to inhibit the proton translocating mitochondrial ATPase were also tested for their ability to inhibit the secretory granule ATPase. A similar pattern of limited inhibition in granules and greater sensitivity in isolated membranes was seen with the inhibitors N,N-dicyclohexylcarbodiimide and efrapeptin. In contrast, tri-n-butyltin chloride was a potent inhibitor of the ATPase of intact granules, and the susceptibility of the enzyme to inhibition by this compound was less after isolation of membranes. These observations suggest that pituitary secretory granule membrane ATPase may have a proton pumping function similar to that of the mitochondrial enzyme. In addition, the data imply that the inhibitor binding site(s) may be masked, inaccessible, or ineffective in intact granules, but exposed (or activated) in isolated membranes. The greater sensitivity of granule ATPase to tri-n-butyltin chloride, in contrast to the greater sensitivity of membrane ATPase to the other inhibitors, indicates that the tin compound may be effective at a membrane site(s) distinct from the others, or that the mechanism of inhibition is different.     

Progress in cellular engineering of plants: biochemical and genetic assessment of selectable markers from cultured cells

Summary Recent availability of stable and well characterized selectable markers and ability to combine alien genomes parasexually have contributed to the development of molecular biology in higher plants, including gene expression and genetic manipulation.Several types of biochemical mutants (resistant to inhibitory concentrations of aminoacid(s) or aminoacid analogs as well as deficient for enzyme activity) have recently been isolated and characterized biochemically and genetically. Among them, mutants with alterations in the nitrogen and aminoacid metabolism, or in the activity of alcohol dehydrogenases are being used in the development of more efficient techniques of gene transfer.The manipulation of whole genomes by sexual or somatic cell fusion offers new potential in this field, but refinement of transfer techniques is desirable. The new set of selectable markers obtained through advanced cellular technology, as well as our ability to regenerate plants from manipulated cell lines are expected to play a major role in cellular engineering.     

Inversions and other unusual heteromorphisms detected by C-banding

Summary Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied.     

Late replicating X chromosomes in human triploidy.

The status of X-chromosome replication was studied in twenty-seven 69,XXY and nine 69,XXX human triploids in which the parental origin of the additional haploid set was known from the study of chromosome heteromorphisms. Among the 69,XXY triploids, fourteen had no late replicating X, two had one late replicating X in all cells examined, and eleven had two populations of cells, one with late replicating X chromosome, and one without any. Among the 69,XXX triploids, four had a single late replicating X, and five had two populations of cells, one with one late replicating X, and one with two late replicating X chromosomes. There was no correlation between the parental origin of the triploidy and the type of X-chromosome inactivation. However the number of late replicating X chromosomes was significantly lower in cultures grown from fetal tissue when compared with those grown from extra-embryonic tissue. In cultures derived from extra-embryonic tissue there was a significant correlation between the gestational age of the sample and the proportion of late replicating X chromosomes. The older the specimen, the greater the number of late replicating X chromosomes.     

Binding of arylazidocytochrome c derivatives to beef heart cytochrome c oxidase: cross-linking in the high- and low-affinity binding sites

Two arylazidocytochrome c derivatives, one modified at lysine-13 and the second modified at lysine-22, were reacted with beef heart cytochrome c oxidase. The lysine-13 modified arylazidocytochrome c was found to cross-link both to the enzyme and with lipid bound to the cytochrome c oxidase complex. The lysine-22 derivative reacted only with lipids. Cross-linking to protein was through subunit II of the cytochrome c oxidase complex, as first reported by Bisson et al. [Bisson, R., Azzi, A., Gutweniger, H., Colonna, R., Monteccuco, C., & Zanotti, A. (1978) J. Biol. Chem. 253, 1874]. Binding studies show that the cytochrome c derivative covalently bound to subunit II was in the high-affinity binding site for the substrate. Evidence is also presented to suggest that cytochrome c bound to the lipid was in the low-affinity binding site [as defined by Ferguson-Miller et al. [Ferguson-Miller, S., Brautigan, D. L., & Margoliash, E. (1976) J. Biol. Chem. 251, 1104]]. Covalent binding of the cytochrome c derivative into the high-affinity binding site was found to inhibit electron transfer even when native cytochrome c was added as a substrate. Inhibition was almost complete when 1 mol of the Lys-13 modified arylazidocytochrome c was covalently bound to the enzyme per cytochrome c oxidase dimer (i.e., congruent to 280 000 daltons). Covalent binding of either derivative with lipid (low-affinity site) had very little effect on the overall electron transfer activity of cytochrome c oxidase. These results are discussed in terms of current theories of cytochrome c-cytochrome c oxidase interactions.