Zooming in on a quantitative trait for tomato yield using interspecific introgressions

To explore natural biodiversity we developed and examined introgression lines (ILs) containing chromosome segments of wild species (Solanum pennellii) in the background of the cultivated tomato (S. lycopersicum). We identified Brix9-2-5, which is a S. pennellii quantitative trait locus (QTL) that increases sugar yield of tomatoes and was mapped within a flower- and fruit-specific invertase (LIN5). QTL analysis representing five different tomato species delimited the functional polymorphism of Brix9-2-5 to an amino acid near the catalytic site of the invertase crystal, affecting enzyme kinetics and fruit sink strength. These results underline the power of diverse ILs for high-resolution perspectives on complex phenotypes.     

Retrospective analysis of selected predictors of mortality within a veterinary intensive care unit

The records of 204 cats entering the intensive care unit (ICU) at the University of Edinburgh Small Animal Hospital between December 2002 and October 2006 were retrospectively analysed. Of these, 37 cats over 12 months of age had a systolic blood pressure recorded on entry into the ICU, and this group comprised our study population. Of these 37 cats, 36 had both heart rate and respiratory rate recorded on entry into the ICU, whilst 24 of these cats also had body temperature recorded. The relationship between (i) survival to discharge and (ii) survival until 21 days after admission to the ICU was analysed using univariate generalised linear models with binomial errors. The robustness of any significant relationship was assessed using multivariate analysis methods. In addition, receiver operator curves (ROC) were generated for any of the significant predictors of mortality and from these curves the threshold values, optimal sensitivity and specificity were calculated. Using these values survival curves were generated for any significant prognostic indexes. A decreased blood pressure at the time of admission to the ICU was found to be a significant negative predictor of survival until discharge from the hospital. Overall, a systolic blood pressure of 124 mmHg or higher at the time of admission to the ICU has a sensitivity of 47.8% and a specificity of 85.7% for predicting that a cat will survive until discharge from the hospital.     

Effects of the nematode Phasmarhabditis hermaphrodita and of venom from the endoparasitic wasp Pimpla hypochondriaca on survival and food consumption of the pest slug Deroceras reticulatum; implications for novel biocontrol strategies

BACKGROUND: Controlling pests through disruption of biochemical pathways by physiologically active compounds/factors from animals and plants represents an expanding field of research. The authors investigated whether such factors in venom from the wasp Pimpla hypochondriaca (Retzius) can affect the viability and food consumption of the slug Deroceras reticulatum (Müller), and whether they can improve the efficacy of nematode-induced slug mortality. RESULTS: Exposure of slugs to 4 mL of water containing 500, 1000 and 5000 Phasmarhabditis hermaphrodita (Schneider) resulted in significant increases in mortality (with hazard ratios of 3.5, 3.9 and 5.8 respectively) and significant reductions in total food consumption and mean food consumption each day for 21 days. Injection of slugs with 4, 8 or 12 microL of P. hypochondriaca venom resulted in significant increases in mortality (with hazard ratios of 3.3, 4.5 and 9.0 respectively) and significant reductions in total food consumption compared with the controls. However, there was no significant effect of venom on the mean food consumption on individual days of the 21 day assay period, although significant reductions occurred for the 8 and 12 microL doses up to day 10. Injecting slugs with 4 microL of venom prior to exposure to 500 nematodes had no synergistic effect on either mortality or food consumption compared with either of the individual treatments. CONCLUSIONS: Pimpla hypochondriaca venom contains factors capable of killing and reducing food consumption by D. reticulatum. The utilization of these factors as components of integrated pest management strategies is discussed.     

Physical and hydraulic properties of baked ceramic aggregates used for plant growth medium.

Baked ceramic aggregates (fritted clay, arcillite) have been used for plant research both on the ground and in microgravity. Optimal control of water and air within the root zone in any gravity environment depends on physical and hydraulic properties of the aggregate, which were evaluated for 0.25-1-mm and 1-2-mm particle size distributions. The maximum bulk densities obtained by any packing technique were 0.68 and 0.64 g cm-3 for 0.25-1-mm and 1-2-mm particles, respectively. Wettable porosity obtained by infiltration with water was approximately 65%, substantially lower than total porosity of approximately 74%. Aggregate of both particle sizes exhibited a bimodal pore size distribution consisting of inter-aggregate macropores and intra-aggregate micropores, with the transition from macro- to microporosity beginning at volumetric water content of approximately 36% to 39%. For inter-aggregate water contents that support optimal plant growth there is 45% change in water content that occurs over a relatively small matric suction range of 0-20 cm H2O for 0.25-1-mm and 0 to -10 cm H2O for 1-2-mm aggregate. Hysteresis is substantial between draining and wetting aggregate, which results in as much as a approximately 10% to 20% difference in volumetric water content for a given matric potential. Hydraulic conductivity was approximately an order of magnitude higher for 1-2-mm than for 0.25-1-mm aggregate until significant drainage of the inter-aggregate pore space occurred. The large change in water content for a relatively small change in matric potential suggests that significant differences in water retention may be observed in microgravity as compared to earth.     

Sensitivity analysis of optimal operation of irrigation supply systems with water quality considerations

A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l^–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m³ h^–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m³ h^–1 reduces the total cost by about 8%.     

Effect of sample type, and timing of assay, on feline blood potassium concentration

Blood samples were collected from 41 cats presented for pre-anaesthetic assessments, routine geriatric screening, or re-assessment of ongoing chronic medical disorders. Samples were either left to clot or anticoagulated with lithium heparin, then assessed for their potassium concentration within 1h of collection, and again after remaining in contact with their cell pellet for 48 h. There was a significantly higher potassium concentration in the serum samples compared to the plasma samples, both in the basal and 48-h samples (although this difference was most marked in the basal samples). Ageing of both serum and plasma samples also resulted in an increase in the potassium concentration when compared with the basal values for each sample type. The mean difference (basal serum minus basal plasma) in potassium concentration was 0.47 mmol/l. While it is probable that the potassium came from either leukocytes and/or thrombocytes the mean total leukocyte count and the mean thrombocyte count were below the upper limit of the reference intervals for our laboratory and the rise in the potassium level did not appear to be directly related to either of these values.     

A genomic library of Lycopersicon pennellii in L. esculentum: A tool for fine mapping of genes

The cultivated tomato contains only a small fraction of the genetic variation present in its wild relatives. In order to use the wild germplasm in tomato breeding and genetic studies we developed a new kind of genetic resource which is composed of 50 L. esculentum lines each containing a single introgression from the green fruited species L. pennellii (LA 716). Each of the introgression lines is nearly isogenic to the cultivated tomato; these lines provide complete coverage of the wild species genome. The lines contain on the average an introgression of 33 cM from a total genome size of 1200 cM. The size and identity of the introgressed segments was determined based on RFLP analysis of 350 markers. This resource can be viewed as a genomic library of the wild species in the cultivated background. It covers the entire genome with single independent inserts per line and therefore every phenotypic difference between the introgression lines can be associated with the unique introgressed segment. The development and potential application of this resource are discussed.     

Assessment of the degree of genetic variation in beet based on RFLP analysis and the taxonomy of Beta

Summary Clones derived from Beta vulgaris and Beta maritima were assayed for their ability to detect restriction fragment length polymorphisms (RFLPs) in different beet accessions. The clones able to detect polymorphism were used as genetic markers to assess the degree of genetic variation existing between and within different species of the genus Beta. The data support the current taxonomy of the Beta vulgaris section, while the great genetic similarity found between Beta webbiana and Beta procumbens indicates that they could belong to the same species.Enough variation was found between Beta vulgaris cultivars, allowing the isolation of a sufficient number of genetic markers for the construction of detailed genetic maps.