scholarly journals Bacterial and Bacteroid Properties of Mutants of Rhizobium Trifolii Strain T1 Uncoupled in Oxidative Phosphorylation

1979 ◽  
Vol 32 (5) ◽  
pp. 501 ◽  
Author(s):  
Mary L Skotnicki ◽  
Barry G Rolfe
Keyword(s):  
Oxidative Phosphorylation ◽  
Atpase Activity ◽  
White Clover ◽  
Parent Strain ◽  
Rhizobium Trifolii ◽  
Selection Technique ◽  
Resistance Selection ◽  
Bacterial Form ◽  
High Level ◽  
Neomycin Resistance

Using the neomycin-resistance selection technique, mutants uncoupled in oxidative phosphorylation were isolated in R. tri/olii strain Tl. These mutants had no detectable ATP-synthesizing activity and between 8 and 20% of the ATP-degrading activity of their parent strain in the bacterial form. The mutants formed nitrogen-fixing nodules on red, white, and subterranean clovers, and bacteroids isolated from white clover nodules had a high level of ATPase activity of about 70% of that found in bacteroids of their parental strain. The possibility that a new ATPase complex is synthesized when the bacteria differentiate to form bacteroids within the nodule is discussed.

scholarly journals Use of Neomycin for Preferential Selection against Rhizobium trifolii in Symbiosis with White Clover (Trifolium repens)

1986 ◽  
Vol 39 (1) ◽  
pp. 23 ◽  
Author(s):  
Brant J Bassam ◽  
Peter M Gresshofr
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Culture System ◽  
Axenic Culture ◽  
Dry Weight ◽  
Rhizobium Trifolii ◽  
In Planta ◽  
Inhibitory Effects ◽  
Transposon Tn5 ◽  
Neomycin Resistance

Symbiotic parameters were tested on neomycin-containing media with antibiotic-sensitive and -resistant Rhizobium trifolii inoculants. Neomycin and kanamycin have similar inhibitory effects on R. trifolii, either antibiotic inhibiting growth at concentrations of 50 mg/!. Transposon Tn5 conferred kanlllTlycin and neomycin resistance to R. trifolii allowing growth on media supplemented with antibiotic *p to concentrations of 400 mg/!. Differential inhibition of nitrate-grown white clover (Trifolium repens) plants in an axenic culture system (Petri plates) was observed in terms of dry weight accumulation and ~isual characteristics. Kanamycin at 50 mgll and neomycin at 200 mgll had similar inhibitory effects on plant growth. Symbiotic development by sensitive R. trifolii cells was severely inhibited by neomycin at concentrations between 50 and 100 mg/l. Plants nodulated by resistant R. trifolii strains maintained co~trol levels of nitrogen ilxation with neomycin concentrations up to 150 mg/!. Thus neomycin is propbsed to be useful as a selective agent against revertants which have lost transposon Tn5 in planta as well as ex planta.

scholarly journals Partial diploids of Escherichia coli carrying normal and mutant alleles affecting oxidative phosphorylation

1977 ◽  
Vol 162 (3) ◽  
pp. 665-670 ◽  
Author(s):  
F Gibson ◽  
G B Cox ◽  
J A Downie ◽  
J Radik
Keyword(s):  
Escherichia Coli ◽  
Fluorescence Quenching ◽  
Oxidative Phosphorylation ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Growth Yields ◽  
Normal Allele ◽  
Adenosine Triphosphatase Activity

A plasmid was isolated which included the region of the Escherichia coli chromosome carrying the known genes concerned with oxidative phosphorylation (unc genes). This plasmid was used to prepare partial diploids carrying normal unc alleles on the episome and one of the three mutant alleles (unc A401, uncB402 or unc-405) on the chromosome. These strains were compared with segregants from which the plasmid had been lost. Dominance of either normal ormutant unc alleles was determined by growth on succinate, growth yields on glucose, Mg-ATPase (Mg2+-stimulated adenosine triphosphatase) activity, atebrin-fluorescence quenching, ATP-dependent transhydrogenase activity and oxidative phosphorylation. In all the above tests, dominance of the normal allele was observed. However, in membranes from the diploid strains which carried a normal allele and either of the mutant alleles affecting Mg-ATPase activity (uncA401 or unc-405), the energy-linked functions were only partially restored.

scholarly journals Protein kinase C-α inhibits the repair of oxidative phosphorylation after S-(1,2-dichlorovinyl)-l-cysteine injury in renal cells

2004 ◽  
Vol 287 (1) ◽  
pp. F64-F73 ◽  
Author(s):  
Xiuli Liu ◽  
Malinda L. Godwin ◽  
Grażyna Nowak
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Oxidative Phosphorylation ◽  
Atpase Activity ◽  
Mitochondrial Function ◽  
Recovery Period ◽  
Β Subunit ◽  
Atp Production ◽  
Kinase C ◽  
Mitochondrial Functions

Previously, we showed that physiological functions of renal proximal tubular cells (RPTC) do not recover following S-(1,2-dichlorovinyl)-l-cysteine (DCVC)-induced injury. This study investigated the role of protein kinase C-α (PKC-α) in the lack of repair of mitochondrial function in DCVC-injured RPTC. After DCVC exposure, basal oxygen consumption (Qo2), uncoupled Qo2, oligomycin-sensitive Qo2, F1F0-ATPase activity, and ATP production decreased, respectively, to 59, 27, 27, 57, and 68% of controls. None of these functions recovered. Mitochondrial transmembrane potential decreased 53% after DCVC injury but recovered on day 4. PKC-α was activated 4.3- and 2.5-fold on days 2 and 4, respectively, of the recovery period. Inhibition of PKC-α activation (10 nM Go6976) did not block DCVC-induced decreases in mitochondrial functions but promoted the recovery of uncoupled Qo2, oligomycin-sensitive Qo2, F1F0-ATPase activity, and ATP production. Protein levels of the catalytic β-subunit of F1F0-ATPase were not changed by DCVC or during the recovery period. Amino acid sequence analysis revealed that α-, β-, and ε-subunits of F1F0-ATPase have PKC consensus motifs. Recombinant PKC-α phosphorylated the β-subunit and decreased F1F0-ATPase activity in vitro. Serine but not threonine phosphorylation of the β-subunit was increased during late recovery following DCVC injury, and inhibition of PKC-α activation decreased this phosphorylation. We conclude that during RPTC recovery following DCVC injury, 1) PKC-α activation decreases F0F1-ATPase activity, oxidative phosphorylation, and ATP production; 2) PKC-α phosphorylates the β-subunit of F1F0-ATPase on serine residue; and 3) PKC-α does not mediate depolarization of RPTC mitochondria. This is the first report showing that PKC-α phosphorylates the catalytic subunit of F1F0-ATPase and that PKC-α plays an important role in regulating repair of mitochondrial function.

scholarly journals Performance of nematode-resistant white clover in field trials

2005 ◽  
pp. 29-34
Author(s):  
C.F. Mercer ◽  
R.N. Watson ◽  
D.R. Woodfield
Keyword(s):  
White Clover ◽  
Field Trials ◽  
Cyst Nematode ◽  
Root Knot Nematode ◽  
Plant Vigour ◽  
Resistant Lines ◽  
Breeding Programmes ◽  
Clover Root ◽  
High Level ◽  
Better Than

Breeding for improved resistance and tolerance to the clover root-knot nematode, Meloidogyne trifoliophila, and the clover cyst nematode, Heterodera trifolii , has been successful in white c lover, Trifolium repens. White clover lines developed from three independent breeding programmes were established in field trials at Lincoln, Palmerston North, Cambridge and Kerikeri. Plants were established in areas either untreated or treated with nematicide, so as to have contrasting pest loads on the plant material and evaluated for up to 4 years. Plant vigour was scored before each grazing at each site. Clover cyst nematode cysts were counted twice in Palmerston North and all nematodes were counted in stained roots on four occasions in Cambridge. Resistant lines from the clover cyst nematode programme performed better than susceptible lines and as well as most cultivars reflecting the high level of resistance developed in this glasshouse-based programme. This resistance was also reflected in the generally lower number of cysts counted under resistant lines from Palmerston North. The root-knot nematode resistant material performed better than the susceptible and as well as most cultivars. The tolerance selections, developed under field conditions, performed as well as, or better than the cultivars. The selections from the breeding programmes have exhibited strong agronomic potential across locations and years and the best material has been crossed, with progeny being assessed in current field trials. Keywords: Heterodera trifolii, Meloidogyne trifoliophila, nematode, pasture, resistance, tolerance, white clover

scholarly journals Maximising seed production potential in white clover: factors influencing seed set per floret

1996 ◽  
Vol 6 ◽  
pp. 41-44
Author(s):  
R.G. Thomas
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Management Practices ◽  
Seed Set ◽  
Head Development ◽  
Light Intensities ◽  
Ovule Sterility ◽  
Growing Conditions ◽  
High Level ◽  
Seed Yields

The causes of low seed set per floret in white clover (Trifolium repens L.) are reviewed. Three stages of flower head development are distinguished as important for a high level of seed set: a pre-fertilisation stage, a stage of anthesis leading to pollination, and a postfertilisation stage in which seed provisioning occurs. In sunny conditions the percentage seed set is limited at the pre-fertilisation stage by up to 20-30% ovule sterility. Relatively low light intensities during the postfertilisation stage can lead to abortion of a high proportion of fertilised ovules and developing seeds. Experimental results suggest that seed yields under optimal growing conditions can be limited solely by the level of pre-fertilisation ovule sterility and probably cannot be bettered, but further understanding of the seed-provisioning requirements for photosynthate could lead to improved management practices for seed production under conditions of lower light intensities. Keywords: abortion, light intensity, ovule, seed provisioning, sterility, white clover

Sign in / Sign up

Export Citation Format

Share Document