An RNA splice site mutation in the C1-inhibitor gene causes type I hereditary angio-oedema

Summary Restriction fragment length polymorphism analysis, the polymerase chain reaction and nucleotide sequencing have been used to characterise a single base substitution (GT) at nucleotide 8863 in the C1-inhibitor gene. This destroys the 5 donor splice site recognition motif of the sixth intron. Family studies suggest that the mutation is responsible for type I hereditary angio-oedema in a studied kindred.     

Efficacy of commercial products in enhancing oil biodegradation in closed laboratory reactors

Summary A laboratory screening protocol was designed and conducted to test the efficacy of eight commercial bacterial cultures and two non-bacterial products in enhancing the biodegradation of weathered Alaska North Slope crude oil in closed flasks. Three lines of evidence were used to support the decision to progress to field testing in Prince William Sound: rapid onset and high rate of oxygen uptake, substantial growth of oil degraders, and significant degradation of the aliphatic and aromatic hydrocarbon fractions of the weathered Alaska North Slope crude oil. A product had to enhance biodegradation greater than that achieved with excess mineral nutrients. Experiments were conducted in closed respirometer flasks and shake flasks, using seawater from Prince William Sound and weathered crude oil from a contaminated beach. Analysis of the data resulted in selection of two of the ten products for field testing. Both were bacterial products. Findings suggested that the indigenous Alaskan microorganisms were primarily responsible for the biodegradation in the closed flasks and respirometer vessels.     

Root:shoot ratios of old and modern,tall and semi-dwarf wheats in a mediterranean environment

A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines for Rht dwarfing genes.Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased.The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns.At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUE_gr) increased from old to modern varieties.The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUE_gr of modern compared to old varieties.     

Influence of mulching on the pattern of growth and water use by spring wheat and moisture storage on a fine textured soil

Eight tonnes ha^–1 of stubble were used to mulch spring wheat (Triticum aestivum) on a fine textured soil with the aim of controlling both transpiration and soil evaporation during the wet pre-anthesis phase to increase moisture supply during grain filling in the eastern wheatbelt of Western Australia. Mulching reduced leaf area per plant by reducing the culm number; consequently the green area index was reduced. Reduced culm number was associated with low soil temperature which at 50 mm depth averaged 7°C lower under the mulched crop relative to the control crop in mid-season. The smaller canopies of the mulched crop used 15 mm less water than those of the control before anthesis; this difference in water-use was due equally to reduced transpiration and soil evaporation. However, the mulched crop was unable to increase ET during grain filling, a response associated with the persistence of low soil temperature for most of the growth period. Hence, total ET for the season was significantly lower (18 mm) under the mulched crop than the control crop. At harvest, mulching did not have significant effects on total above-ground dry matter and grain yields, but it increased water use efficiency for grain yield by 18%, grain weight by almost 17% and available moisture in both uncropped and cropped plots by an average of 43 mm.To determine whether there was any residual effects of soil treatment on moisture storage during the summer fallow period, soil moisture was monitored both in cropped plots and uncropped plots, that were either mulched or unmulched during the growing season, from harvest in October 1988 until next planting in June 1989. Available moisture at next planting was correlated with moisture storage at harvest despite the differences in run-off, soil evaporation and fallowing efficiency (increase in moisture storage as a percentage of rainfall) between treatments during fallowing. Therefore, the mulched treatments had more moisture available (30 mm), mostly as a result of less water use during cropping in the previous growing season, than the unmulched treatment.The study shows that mulching may be used to restrain both transpiration and soil evaporation early in the season to increase availability of soil moisture during grain filling. Secondly, mulching during the previous growing season had little effect on soil moisture during the summer fallow period, however, the moisture saved by mulching during cropping was conserved for the following season. These results indicate the importance of evaluating mulching of winter crops in terms of crop yield in the subsequent growing season as well as in the current season in which the soil was treated.Abbreviations D through drainage - DAS days after sowing of the crop on 31 May 1988 - DM dry matter produced in the above-ground portion of the crop (kg ha^–1) - E₀ evaporation from Class A pan (mm) - E_s evaporation from uncropped soil (mm) - E_sc evaporation from soil beneath the wheat canopy (mm) - ET evapotranspiration (mm) - FE fallowing efficiency (gain in soil moisture storage/rainfall) - GAI green area index (area of green vegetation per unit land area) - GWUE water-use efficiency for grain production (grain yield/total ET, kg ha^–1mm^–1) - K extinction coefficient (see equation 1) - RO run-off of moisture from soil surface during/following rainfall (mm) - SM available soil moisture (mm) at harvest (SMh) or at planting (SMp) - WUE water-use efficiency for total above-ground dry matter yield (see GWUE)     

Carbon Isotope Discrimination is not Correlated with Transpiration Efficiency in Three Cool-Season Grain Legumes （Pulses）

The carbon isotope discrimination （δ^13C） of leaves has been shown to be correlated with the transpiration efficiency of leaves in a wide range of species. This has led to δ^13C being used in breeding programs to select for improved transpiration efficiency. The correlation between δ^13C and transpiration efficiency was determined under well-watered conditions during the vegetative phase in six genotypes of lentil （Lens culinaris Medikus）, six genotypes of chickpea （Cicerarietinum L.） and 10 cultivars of narrow-leafed lupin （Lupinus angustifolius L.）. Biomass （dry matter） accumulation and water use （transpiration） varied among the genotypes in all three species and transpiration efficiency was 40% to 75% higher in the most efficient compared with the least efficient genotypes. However, δ^13C and transpiration efficiency were not significantly correlated in any of the species. This suggests that the δ^13C technique cannot be used in selection for transpiration efficiency in the three grain legumes （pulses） studied.     

Characterization of recombinant endo-1,4-β-xylanase of Bacillus halodurans C-125 and rational identification of hot spot amino acid residues responsible for enhancing thermostability by an in-silico approach

Increased demand of enzymes for industrial use has led the scientists towards protein engineering techniques. In different protein engineering strategies, rational approach has emerged as the most efficient method utilizing bioinformatics tools to produce enzymes with desired reaction kinetics; physiochemical (temperature, pH, half life, etc) and biological (selectivity, specificity, etc.) characteristics. Xylanase is one of the widely used enzymes in paper and food industry to degrade xylan component present in plant pulp. In this study endo 1,4-β-xylanase (Xyl-11A) from Bacillus halodurans C-125 was cloned in pET-22b (+) vector and expressed in Escherichia coli BL21 (DE3) expression strain. The enzyme had Michaelis constant K_m of 1.32 mg ml^?1 birchwoodxylan (soluble form) and maximum reaction velocity (V_max) 73.53 mmol min^?1 mg^?1 with an optimum temperature of 75 °C and pH 9.0. The thermostability analysis showed that enzyme retained more than 80% of its residual activity when incubated at 75 °C for 2 h. In addition, to increase Xyl-11A thermostability, an in-silico analysis was performedto identify the hot spot amino acid residues. Consensus-based amino acid substitution was applied to evaluate multiple sequence alignment of homologs and identified 20 amino acids positions by following Jensen-Shnnon Divergence method. 3D models of 20 selected mutants were analyzed for conformational transition in protein structures by using NMSim server. Two selected mutants T6K and I17M of Xyl-11A retained 40, 60% residual activity respectively, at 85 °C for 120 min as compared to wild type enzyme which retained 37% initial activity under same conditions, confirming the enhanced thermostability of mutants. The present study showed a good approach for the identification of promising amino acid residues responsible for enhancing the thermostability of enzymes of industrial importance.

     

Frequency Distribution of F-Latencies (DFL) has Physiological Significance and Gives Distribution of Conduction Velocity (DCV) of Motor Nerve Fibres With Implications for Diagnosis

On electrical stimulation of a peripheral motor nerve, a delayed and reduced F-response is obtained, which is known to occur due to random backfiring of a few percent of the motor nerve fibres at the spinal end after antidromic conduction. F-latencies obtained from multiple stimulations vary in latency, size and shape because of this randomness. We hypothesised that, being a random process, recruitment of fibres for F-response would depend on the distribution of conduction velocity (DCV) for motor nerve fibres directly, and therefore, a frequency distribution of F-latencies (DFL) from such multiple F-responses would be an approximate mirror image of DCV, latency being inversely proportional to velocity. First, obtaining DFL from many human subjects, we have shown that this is a reproducible parameter for a nerve trunk of a subject, and hence reveals a new physiological phenomenon. DFL has a single peaked distribution, which is also expected for the DCV of a normal healthy motor nerve. To validate its hypothesised relationship to DCV further, DFLs were obtained from both median nerves of patients with unilateral carpal tunnel syndrome (CTS). The patterns of DFL from both sides remained almost the same except for a delay shift equal to that in between the two M-responses, which lends support to this hypothesis. DFL, and DCV as its suggested mirror image, appear to change systematically with certain known disorders such as cervical spondylosis, even at a subclinical stage, which needs further study. This also indicates that DFL may become a new and improved investigative diagnostic tool in neurophysiology.