QTLs associated with root traits increase yield in upland rice when transferred through marker-assisted selection

Altering root morphology of rice (Oryza sativa L.) cultivars could improve yields in drought-prone upland ecosystems. Marker-assisted backcross breeding was used to introgress four QTLs for root traits into an upland rice cultivar. The QTLs had previously been identified under experimental conditions in a different genetic background. The introgressed lines and the recurrent parent were grown for 6 years by resource-poor farmers in upland sites in Eastern India and yields recorded. In combination the QTLs significantly increased yield by 1 t ha^?1 under relatively favourable field conditions. In less favourable trials, the QTL effects were not detected due to greater heterogeneity in soil–water availability in very low yielding environments and consequent yield variability. Root studies under controlled conditions showed that lines with the introgressions had longer roots throughout tillering than the recurrent parent (14 cm longer 2 weeks after sowing). Therefore, both improved roots and increased yield can be attributed to the introgression of QTLs. This is the first demonstration that marker-assisted backcross breeding (MABC) to introgress multiple root QTLs identified under controlled conditions is an effective strategy to improve farmers’ yields of upland rice. The strategy was used to breed a novel upland rice cultivar that has been released in India as Birsa Vikas Dhan 111.     

The purine nucleotide cycle in the regulation of ammoniagenesis during induction and cessation of chronic acidosis in the rat kidney.

The effect of chronic acid feeding and its subsequent withdrawal was determined on the amounts of the metabolic intermediates and enzymic activities of the purine nucleotide cycle. Sprague-Dawley rats were given 1.5% (w/v) NH4Cl in their drinking water for 5 days. The renal excretion of NH3 rose 70-fold and the rats developed acidosis. The amount of renal IMP rose from a control value of 4.5 +/- 2.2 to 20.4 +/- 3.7nmol/g of kidney after 48h of acid feeding (P less than 0.001) and fell to normal within 48h of the recovery. Adenylosuccinate concentrations fell from a control value of 4.5 +/- 0.9nmol/g of kidney to 1.2 +/- 0.3nmol/g (P less than 0.005) by day 5 of acidosis and continued to fall to undetectable values by 48h after recovery. The amount of AMP remained constant through the acid-feeding and the recovery periods. The activity of adenylosuccinate synthetase, the rate-limiting enzyme of the purine nucleotide cycle, paralleled the rise and fall in NH3 excretion. The activities of phosphate-dependent glutaminase and glutamate dehydrogenase were elevated during the acid-feeding and the recovery period. Thus changes in the purine nucleotide cycle correlate with changes in NH3 excretion to a more parallel degree than does the activity of glutaminase or glutamate dehydrogenase.     

Effects of chair restraint on the strength of the tibia in rhesus monkeys

To determine the effects of the relative inactivity and unloading on the strength of the tibias of monkeys, Macaca mulatta, we used a non-invasive test to measure bending stiffness, or EI (Nm2), a mechanical property. The technique was validated by comparisons of in vivo measurements with standard measures of EI in the same bones post-mortem (r2 = 0.95, P < 0.0001). Inter-test precision was 4.28+/-1.4%. Normative data in 24 monkeys, 3.0+/-0.7 years and 3.6+/-0.6 kg, revealed EI to be 16% higher in the right than left tibia (4.4+/-1.6 vs. 3.7+/-1.6 Nm2, P < 0.05). Five monkeys, restrained in chairs for 14 days, showed decreases in EI. There were no changes in EI in two chaired monkeys that lost weight during a 2-week space flight. The factors that account for both the decreases in bone mechanical properties after chair restraint at 1 g and lack of change after microgravity remain to be identified. Metabolic factors associated with body weight changes are suggested by our results.     

Comparative High-Density Microarray Analysis of Gene Expression during Growth of Lactobacillus helveticus in Milk versus Rich Culture Medium

Lactobacillus helveticus CNRZ32 is used by the dairy industry to modulate cheese flavor. The compilation of a draft genome sequence for this strain allowed us to identify and completely sequence 168 genes potentially important for the growth of this organism in milk or for cheese flavor development. The primary aim of this study was to investigate the expression of these genes during growth in milk and MRS medium by using microarrays. Oligonucleotide probes against each of the completely sequenced genes were compiled on maskless photolithography-based DNA microarrays. Additionally, the entire draft genome sequence was used to produce tiled microarrays in which noninterrupted sequence contigs were covered by consecutive 24-mer probes and associated mismatch probe sets. Total RNA isolated from cells grown in skim milk or in MRS to mid-log phase was used as a template to synthesize cDNA, followed by Cy3 labeling and hybridization. An analysis of data from annotated gene probes identified 42 genes that were upregulated during the growth of CNRZ32 in milk (P < 0.05), and 25 of these genes showed upregulation after applying Bonferroni's adjustment. The tiled microarrays identified numerous additional genes that were upregulated in milk versus MRS. Collectively, array data showed the growth of CNRZ32 in milk-induced genes encoding cell-envelope proteinases, oligopeptide transporters, and endopeptidases as well as enzymes for lactose and cysteine pathways, de novo synthesis, and/or salvage pathways for purines and pyrimidines and other functions. Genes for a hypothetical phosphoserine utilization pathway were also differentially expressed. Preliminary experiments indicate that cheese-derived, phosphoserine-containing peptides increase growth rates of CNRZ32 in a chemically defined medium. These results suggest that phosphoserine is used as an energy source during the growth of L. helveticus CNRZ32.     

Peroxide induced chemiluminescence in an in vitro proline hydroxylation system.

This communication describes a hydrogen peroxide (HOOH) induced chemiluminescence (CL) in an in vitro aromatic (proline) hydroxylation system. The reactive components of the system are ascorbic (AA), ethylene diamine tetraacetic disodium salt (EDTA), ferrous sulfate, and HOOH. The CL is (1) nearly dissipated within three minutes, (2) enhanced and/or sustained by proline and polylysine to a greater degree than by alanine, (3) partially inhibited by a,a' dipyridyl, EDTA, and ethanol, (4) most dependent upon the presence of Fe2+, AA, and HOOH. The in vitro proline hydroxylation system is more effective than ground state oxygen in terms of the CL produced and the percent of hydroxyproline formed.     

DNA-DNA homology among lactose- and sucrose-fermenting transconjugants from Lactococcus lactis strains exhibiting reduced bacteriophage sensitivity.

DNA-DNA homology between a reduced bacteriophage sensitivity (Rbs+) probe and DNA from both Rbs+ and Rbs- Lactococcus lactis strains was examined. Homology was detected between the probe and five plasmids (pCI750, pCC34, pEB56, pNP2, and pJS88) isolated from lactose-positive Rbs+ transconjugants and between the probe and genomic DNA of a sucrose-positive Rbs+ transconjugant. Additionally, hybridizations conducted between the probe and plasmids reported to encode abortive bacteriophage infection indicated homology with pTR2030 but not with pBF61 and pGBK17. The results suggest that a common genetic determinant(s) may be present in a variety of lactococcal plasmids coding for Rbs+.     

Detection and characterization of erythromycin-resistant methylase genes in Gram-positive bacteria isolated from poultry litter

The epidemiology of four erythromycin-resistant methylase ( erm) genes, ermA, ermB, ermC and msrA, was determined in erythromycin-resistant staphylococci, enterococci and streptococci isolated from poultry litter. All isolates were resistant to multiple antibiotics. Southern hybridization indicated that 4 of the 20 staphylococci contained the ermC gene on plasmids: on a 2.2 kb plasmid in Staphylococcus hominis and S. sciuri, on a 6.0 kb plasmid in S. xylosus, and on a 7.0 kb plasmid in S. lentus. In 16 of the 20 staphylococci, the ermA gene was harbored exclusively on the chromosome, as a double chromosomal insert on 8.0 and 6.2 kb EcoRI fragments. None of the staphylococci harbored the msrA gene. Dot-blot analysis indicated that all enterococci and streptococci hybridized with a biotinylated ermB gene probe. Southern hybridization indicated that only 2 of the 19 erythromycin-resistant enterococci contained the ermB gene on plasmids. The gene was localized on 4.0 kb and 5.9 kb plasmids, respectively, in two Enterococcus faecium isolates. Results from our studies indicate that the patterns of occurrence of erm genes, the sizes of the plasmids and the copy numbers of the inserts were different from the existing information on the presence of erm genes in clinical strains of Staphylococcus spp.     

An analysis of avoidance generalization and food preference transitivity in goldfish,Carassius auratus

To examine the effect of novelty in food selection by fishes, goldfish were trained by feeding them on red or green food pellets. Individual fish and fish in shoals of two, three, and five were then given a choice between equal numbers of familiar pellets and novel (yellow) pellets. In experimental groups, the yellow pellets were soaked in 15% quinine hydrochloride to make them unpalatable. Fish were next presented with equal numbers of familiar and a second novel pellet. It was expected that fish would generalize from their experience with the unpalatable pellets and demonstrate avoidance to sampling a second novel food item. However, as groups, neither controls nor experimentals were reluctant to sample the second novel pellets. Also, fish did not eat significantly more familiar than novel pellets when both were palatable. A third set of experiments examined food preference transitivity in which each pellet type was presented alone and in three pair-wise combinations to individual fish. Although red and yellow pellets were preferred over green, they were preferred equally, indicating an absence of transitivity in pellet choice and, perhaps, a “preference” for a mixture of red and yellow pellets.