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41.
Alberto Barros M. Carmo Tavares Sérgio Castedo M. Salomé Pereira M. Purificação Tavares M. Almeida e Costa 《Human genetics》1987,75(4):388-390
Summary A double balanced reciprocal translocation involving four chromosomes, t(1;19;6;14) (1p11; 19p11; 6q25; 14q21), was found in the phenotypically normal husband in a couple referred because of repeated abortions. Reciprocal translocations, t(6;14), had been transmitted by his mother, his father being apparently homozygous for a translocation comprising pairs 1 and 19-t(1;19)(1;19). The genetic consequences of this complex chromosomal rearrangement are analyzed. 相似文献
42.
B. Koukalová J. Reich R. Matyášek V. Kuhrová M. Bezděk 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(1):77-80
Summary HRS60.1, a monomer unit (184 bp) of a highly repeated nuclear DNA sequence of Nicotiana tabacum, has been cloned and sequenced. Following BamHI digestion of tobacco DNA, Southern hybridization with HRS60.1 revealed a ladder of hybridization bands corresponding to multiples of the basic monomer unit. If the tobacco DNA was digested with restriction endonucleases which have no target site in HRS60.1, the larger part of DNA homologous to HRS60.1 remained as uncleaved relic DNA. These results suggest a tandem arrangement of this DNA repeat unit. Four other clones of tobacco nuclear DNA cross-hybridized with HRS60.1, thus forming a HRS60-family. Sequencing their inserts has shown their strong mutual homology. HRS60-family comprised about 2% of the nuclear genome of N. tabacum. Computer comparisons with other tandem plant-repeated DNA sequences could not detect any other homologous sequence. 相似文献
43.
L. O. e Silva S. P. Singh M. A. Pastor-Corrales 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(5):619-624
Summary Inheritance of resistance to common bacterial blight in the trifoliate leaf, plant canopy, and pods was controlled by a single major gene. Additive followed by dominance effects were more important than epistatic interactions. Narrow-sense heritability values ranged from 0.18 to 0.87 for trifoliate leaf, from 0.26 to 0.76 for canopy, and from 0.11 to 0.36 for pods. Observed gains from selection for resistance were higher than expected gains. Implications of these results in breeding for resistance are discussed. 相似文献
44.
Glutamate dehydrogenase in disrupted mitochondrial preparations is activated by L-leucine to a much greater extent than is the purified enzyme. A factor, or factors, responsible for modulating the sensitivity of L-leucine is lost during the purification of the enzyme. Although both cardiolipin and phosphatidylserine are inhibitors of the enzyme, only the inhibition by the former phospholipid is reversed by L-leucine. The inhibition of glutamate dehydrogenase by its binding to cardiolipin in the disrupted mitochondrial preparations and its relief by L-leucine could account for the greater sensitivity of such preparations to activation by that amino acid. 相似文献
45.
Summary The threonine operon fromEscherichia coli was cloned in plasmid pBR322, subcloned into the shuttle vector pCEM300 and the resulting recombinant plasmid was transferred intoBrevibacterium flavum andCorynebacterium glutamicum. The expression ofE. coli threonine genes in these coryneform bacteria was demonstrated by complementing thethrA andthrB mutations and by assaying homoserine dehydrogenase activity. 相似文献
46.
Denis Roy Marco Lagimonire Marie-Jose Hardy Jean-Franois Bourassa Pierre Mourot 《Journal of biotechnology》1989,10(3-4):227-240
Factors affecting the viability and infectivity of an ectomycorrhizal fungus during moderate concentration by cross-flow filtration were determined. Mycelial suspensions were concentrated with three commercial membrane filters (Prostak Millipore Co., M14 Tech-Sep Co. and Ceraflo Norton Co.) under aseptic conditions. Medium components may reduce the filtration rate due to their low solubility. An antifoam agent did not reduce the average flux rates as much as did the malt extract. Clear unobstructed channels (I.D. 6mm) of the tubular modules (Tech-Sep) gave the best results both in terms of performance (filtration rate) and cell viability. Shear stresses caused by pumping and flow through narrow retentate channels were probably responsible for lowering viability and infectivity. There was no linear relationship between permeate fluxes and cell concentration. There is an optimum pore size both in terms of performance (filtration rate) and cell viability. Physical blockage of large pores by hyphae could explain lower permeate flux rates than those obtained with lower pore sizes membranes. 相似文献
47.
Miroslav Pátek Jan Nešvera Jitka Hochmannová 《Applied microbiology and biotechnology》1989,31(1):65-69
Summary Four hybrid plasmids were constructed from the cryptic plasmid pAM330 (from Brevibacterium lactofermentum; 4.5 kb) and the broadhost-range plasmid pGV1106 (9.0 kb; Kmr Smr) isolated from Escherichia coli. All of them were mobilized from E. coli into the Gram-negative methylotrophic bacterium Methylobacillus sp. and two of these constructs (pCEM300 and pCEM400) were transferred by transformation into B. flavum and Corynebacterium glutamicum. Their kanamycin-resistance determinant coming from Gram-negative hosts was expressed in these Gram-positive bacteria. Both pCEM300 and pCEM400 are very stably maintained in B. flavum and represent suitable vectors for gene cloning in coryneform producers of amino acids. 相似文献
48.
Aleš Vančura Ivana Vančurová Jan Kopecký Jaroslav Maršálek Daniel Cikánek Gabriela Basařová Vladimir Křišťan 《Archives of microbiology》1989,151(6):537-540
Synthesis of threonine dehydratase in Streptomyces fradiae was positively influenced by valine and negatively by isoleucine. However, these two amino acids had no effect on the activity of this enzyme. Synthesis of threonine dehydratase in -aminobutyrate resistant mutants of S. fradiae was pronouncedly less sensitive to the positive effect of valine and this change in regulation led to valine overproduction. Synthesis of acetohydroxy acid synthase is regulated in a similar manner to that of threonine dehydratase, however a lower level of expression was detected in -aminobutyrate resistant mutants. And again, no effect of branched-chain amino acids on acetohydroxy acid synthase activity was observed. It follows that in S. fradiae synthesis of threonine dehydratase is the main regulatory mechanism governing production and the mutual ratio of synthesized valine and isoleucine.Abbreviations -AB
-aminobutyrate
- AHAS
acetohydroxy acid synthase
- -KB
-ketobutyrate
- MNNG
N-methyl-N-nitro-N-nitrosoguanidine
- TD
threonine dehydratase
- Trans. B.
transaminase of branched-chain amino acids
- VDH
valine dehydrogenase 相似文献
49.
BasidiomycetesPhellinus chrysoloma, Kuehneromyces mutabilis andGanoderma applanatum produce extracellular milk-clotting enzymes. The enzymes are acid proteinases stable at 40°C and within pH 3–5.5. Only the
enzyme preparation fromP. chrysoloma exhibits properties comparable with animal chymosin. 相似文献
50.
High-performance liquid chromatography was used to estimate 3-ketolactose and 3-ketosucrose in cultures of agrobacteria. The
activities of enzymes that convert the disaccharide substrate were evaluated during batch cultivation ofAgrobacterium tumefaciens on sucrose, maltose, and lactose. The highest activity of glucoside 3-dehydrogenase and a slight activity of disaccharide-hydrolyzing
enzymes were found in cells grown on lactose. Nongrowing cells converted lactose to 3-ketolactose faster than immobilized
cells did. Immobilization of cells into polysaccharide gels did not stabilize the activity of glucoside 3-dehydrogenase. Glutaraldehyde
cross-linking of the cell content led to an inactivation of the respiratory chain but Fe3+ could be used as an electron acceptor. Cells treated with glutaraldehyde converted lactose faster than nongrowing ones but
the activity of glucoside 3-dehydrogenase was not stable. 相似文献